WO2001024196A1 - Fuel assembly - Google Patents

Fuel assembly Download PDF

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Publication number
WO2001024196A1
WO2001024196A1 PCT/JP1999/005354 JP9905354W WO0124196A1 WO 2001024196 A1 WO2001024196 A1 WO 2001024196A1 JP 9905354 W JP9905354 W JP 9905354W WO 0124196 A1 WO0124196 A1 WO 0124196A1
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WO
WIPO (PCT)
Prior art keywords
fuel
rods
rod
water
assembly
Prior art date
Application number
PCT/JP1999/005354
Other languages
French (fr)
Japanese (ja)
Inventor
Akihito Orii
Junichi Koyama
Koji Nishida
Masao Chaki
Toru Kanazawa
Original Assignee
Hitachi, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi, Ltd. filed Critical Hitachi, Ltd.
Priority to PCT/JP1999/005354 priority Critical patent/WO2001024196A1/en
Priority to JP2001527296A priority patent/JP4099990B2/en
Publication of WO2001024196A1 publication Critical patent/WO2001024196A1/en

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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/30—Assemblies of a number of fuel elements in the form of a rigid unit
    • G21C3/32—Bundles of parallel pin-, rod-, or tube-shaped fuel elements
    • G21C3/326—Bundles of parallel pin-, rod-, or tube-shaped fuel elements comprising fuel elements of different composition; comprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods
    • G21C3/328—Relative disposition of the elements in the bundle lattice
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/30—Assemblies of a number of fuel elements in the form of a rigid unit
    • G21C3/32—Bundles of parallel pin-, rod-, or tube-shaped fuel elements
    • G21C3/322—Means to influence the coolant flow through or around the bundles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to a fuel assembly, and more particularly to a fuel assembly having a plurality of fuel rods arranged in 10 rows and 10 columns, which is suitable for application to a boiling water reactor.
  • the moderator in the fuel assembly is increased with the increase in the concentration of fissile material.
  • the proportion also needs to be increased.
  • Japanese Patent Application Laid-Open No. 7-234293 describes a fuel assembly in which fuel rods are arranged in 9 rows and 9 columns and a burnup of 45 GW d Zt can be obtained.
  • this fuel assembly two large-diameter water inlets are placed in the area where seven fuel rods can be placed at the center of the cross section, and the length in the axial direction is shorter than the other fuel rods.
  • the book has short fuel rods. These short fuel rods improve the pod coefficient of the fuel assembly.
  • the use of short fuel rods Since the area of the cooling water passage is increased in the gas-liquid two-phase flow region, the pressure loss of the fuel assembly is reduced. Many fuel assemblies with a fuel rod array of 9 rows and 9 columns or more use short fuel rods.
  • Japanese Patent Application Laid-Open No. 5-232273 describes a fuel assembly having a fuel rod array of 10 rows and 10 columns.
  • this fuel assembly short fuel rods are arranged adjacent to the non-boiling water region (water inlet, gap water region) so that the neutron moderating effect is promoted and the effect of improving the void coefficient is increased. Disclosure of the invention
  • An object of the present invention is to provide a fuel assembly capable of achieving higher core burnup and achieving acceptable core stability without increasing pressure loss as compared with conventional fuel assemblies. It is in.
  • the first invention has a plurality of first fuel rods and a plurality of second fuel rods shorter in length than the first fuel rods.
  • a plurality of water rods are arranged in a row of 10 fuel rods and occupy an area where eight fuel rods can be arranged, and the second fuel rod is arranged in an outermost fuel rod array.
  • the sum of the cross-sectional areas of the water port is Awr
  • the cross-sectional area of the coolant flow path below the fuel assembly is Ach
  • the active fuel length of the first fuel rod is L.
  • the number of the second fuel rods is ⁇
  • the active fuel length of the second fuel rods is L p
  • the average burnup B (GW d / t). Construct to satisfy, B> 6 0... (Equation 1)
  • the present invention satisfies the respective expressions of the above conditions is the burnup It can be further increased, and acceptable core stability can be obtained without increasing the pressure loss as compared with the conventional fuel assembly.
  • a feature of the second invention that achieves the above object is that it has a plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods, and these fuel rods have 10 rows.
  • a plurality of water inlets occupying an area where nine fuel rods can be arranged are arranged in a 10-row fuel rod array, and the second fuel rod is arranged in an outermost fuel rod array.
  • the number of the second fuel rods is ⁇ , the active fuel length of the second fuel rods is L p, and the average burnup is B (GW d Z t). Configure to satisfy.
  • the feature of the third invention that achieves the above object is that it has a plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rod, and these fuel rods have one or more fuel rods.
  • a plurality of water rods are arranged in a fuel rod array of 0 rows and 10 columns, and occupy an area where 10 fuel rods can be arranged, and the second fuel rods are arranged in an outermost fuel rod array.
  • a fuel assembly that is not disposed in the fuel assembly, wherein the sum of the cross-sectional areas of the water inlets is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach,
  • the active fuel length is Lf
  • the number of the second fuel rods is n
  • the active fuel length of the second fuel rod is Lp
  • the average burnup is B (GWd / t), Configure to satisfy the indicated relationship.
  • the features of the fourth invention for achieving the above object are a plurality of first fuel rods, It has a plurality of second fuel rods shorter in length than the first fuel rods, and these fuel rods are arranged in a fuel rod array of 10 rows and 10 columns, and eight fuel rods can be arranged A plurality of water rods occupying an area, wherein the second fuel rods are located both in the outermost fuel rod array and adjacent to the water port array, and in the outermost fuel rod array.
  • a fuel assembly arranged at any one of the following positions, wherein the sum of the cross-sectional areas of the water rod is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach,
  • the active fuel length of the first fuel rod is L f
  • the number of the second fuel rods is n
  • the active fuel length of the second fuel rod is L p
  • the average burnup is B (GW d / t).
  • a feature of the fifth invention that achieves the above object is that the fifth invention has a plurality of first fuel rods and a plurality of second fuel rods shorter in length than the first fuel rods.
  • a plurality of water rods are arranged in a 10-row fuel rod array, and occupy an area where nine fuel rods can be placed, and the second fuel rod has an outermost fuel rod.
  • a fuel assembly arranged at one of the position in the fuel rod array and the position adjacent to the water port, and only the position in the outermost fuel rod array, and The sum of the cross-sectional areas is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach, the active fuel length of the first fuel rods is Lf, the number of the second fuel rods is ⁇ , When the active fuel length of the second fuel rod is L ⁇ and the average burnup is B (GW d Z t), the configuration is such that the relationship shown in the following equation is satisfied.
  • a feature of the sixth invention that achieves the above object is that the sixth invention has a plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods.
  • a plurality of water rods are arranged in a 10-row fuel rod array and occupy an area where 10 fuel rods can be placed, and the second fuel rod is provided in the outermost fuel rod array.
  • a fuel assembly arranged at any one of the position and the position adjacent to the water port, and only the position in the outermost fuel rod array, and the sum of the cross-sectional areas of the water rods Aw r, the lower part of the fuel assembly Is the cross-sectional area of the coolant flow path at A ch, the active fuel length of the first fuel rod is L f, the number of the second fuel rods is n, the active fuel length of the second fuel rod is L p, and
  • B GWd / t
  • FIG. 1 is a longitudinal sectional view of a fuel assembly according to a preferred embodiment of the present invention
  • FIG. 2 is a transverse sectional view of the fuel assembly shown in FIG. 1
  • FIG. 3 is determined from pressure loss.
  • Fig. 4 is an explanatory diagram of the width reduction ratio as an indicator of stability in a stable state.
  • Fig. 5 is an explanatory diagram of the width reduction ratio as an indicator of stability in an unstable state.
  • FIG. 6 shows the effective fuel length of the short fuel rod 2B Lp and the effective fuel length Lf of the fuel rod 2A and the total cross section of the water port determined from the core stability.
  • Area Aw r A characteristic diagram showing the relationship with the coolant flow path area A ch in the fuel assembly
  • FIG. 7 is a characteristic diagram showing each characteristic shown in FIG. 3 and FIG. 6,
  • Fig. 10 is a cross sectional view of a fuel assembly according to another embodiment of the present invention.
  • Fig. 10 is a short fuel rod 2B determined from pressure loss and core stability in the fuel assembly of Fig. 9.
  • FIG. 11 is a characteristic diagram showing the relationship between the active fuel length Lp Z of the fuel rod 2A and the active fuel length L f of the fuel rod 2A and the total cross-sectional area Aw r Z of the coolant passage area Ach in the fuel assembly.
  • FIG. 12 is a cross-sectional view of a fuel assembly according to another embodiment of the present invention, and FIG. 13 is a diagram showing the fuel assembly of FIG. 12 determined from pressure loss and core stability.
  • FIG. 17 and FIG. 18 are cross-sectional views of a fuel assembly according to another embodiment of the present invention, and FIG.
  • FIG. 20 is a cross-sectional view of a fuel assembly according to another embodiment of the present invention
  • FIG. 22 is a cross-sectional view of the fuel assembly of FIG. 21.
  • Pressure drop Effective fuel length of short fuel rod 2B Lp Z Effective fuel length Lf of fuel rod 2A and total cross-sectional area of water rod Awr
  • FIG. 23 is a characteristic diagram showing the relationship with the area A ch
  • the poiid coefficient is mainly affected by the water rod area, the number and length of short fuel rods, and the arrangement.
  • the effect of the void coefficient on the number and length of the short fuel rods on the core stability has not been quantitatively evaluated. Considering the backfit to the current core, it is necessary to achieve core stability equivalent to that of conventional fuel.If the above void coefficient is not sufficiently evaluated, core stability that can achieve high burnup can be achieved. The evaluation (water rod area, number of short fuel rods, length) is not sufficient.
  • the effect on the pressure loss of the aggregate which is important for backfitting, in other words, the effects of the water inlet area, the number of short fuel rods, and the length on the pressure loss are not considered.
  • FIG. 1 This fuel assembly 1 is loaded into the core of a boiling water reactor.
  • the fuel rods 2 are arranged in a square matrix of 10 rows and 10 columns.
  • the fuel rod 2 includes a fuel rod 2A having a longer axial length and a short fuel rod 2B having a shorter axial length than the fuel rod 2A.
  • Two water rods 3 are arranged in the center of the cross section of the fuel assembly 1.
  • Each water port 3 has a circular cross section and has a size occupying an area where four fuel rods can be arranged.
  • the two water rods 3 are arranged so that each axis is on one diagonal line of the fuel assembly 1.
  • These water rods 3 are located in the area within the fourth layer from the outside of the fuel rod array, and the other diagonal line (the fuel assembly 1 is controlled while loaded in the core of a boiling water reactor) Corner facing rod (Diagonal line to part 8).
  • the upper end of the fuel rod 2 A and the water port 3 is held by the upper plate 4, and the lower end is held by the lower plate 5.
  • the lower end of the short fuel rod 2 B is held by the lower tie plate 5.
  • the fuel rods 2A, 2B and the water port 3 are held at a predetermined distance from each other by a fuel spacer 5.
  • These fuel rods are housed in a channel box 7 mounted on the upper tie plate 4.
  • the short fuel rods 2 B are arranged in the second layer from the outside of the fuel rod arrangement.
  • the 12 short fuel rods 2B are arranged at each corner and at a position spaced one from each corner.
  • the remaining four short fuel rods 2 B are arranged adjacent to the water rod 3.
  • the inner width D cb of the channel box 7 is about 1334 ⁇
  • the outer diameters D f of the fuel rods 2A and 2B are 10.26 nun
  • the fuel rod pitch P f is 12 .95 mm
  • the effective fuel length L f of the fuel rod 2 A is about 3.7 m.
  • the short fuel rods 2B are not arranged on the outermost layer of the fuel rod array.
  • the fuel assembly 1 of this embodiment is configured such that the active fuel length L p of the short fuel rod 1 B and the total cross-sectional area A wr of the water port 2 satisfy the conditions of (Equation 1) to (Equation 6). It was done.
  • the conditions of (Equation 1) to (Equation 6) have been found through the study of the inventors. The results of these studies are described in detail below.
  • Equation 6 determined from the pressure loss of the fuel assembly will be described.
  • the present inventors used the number of short fuel rods and the effective fuel length of the short fuel rods as parameters, as shown in JP-A-7-234293.
  • Conventional fuel assemblies (hereinafter simply referred to as conventional fuel assemblies)
  • the total cross-sectional area of the water inlet head 3 that has the same pressure loss as the pressure loss of the water outlet head 3 is determined, and the relationship between the number of short fuel rods, the active fuel length L p of the short fuel rods, and the total cross-sectional area of all water outlet heads is determined. Revealed. Figure 3 shows their relationship. In FIG.
  • the horizontal axis represents the ratio (L p ZL f) of the active fuel length L f of the fuel rod 2 A to the active fuel length L p of the short fuel rod 2 B, and the vertical axis represents the fuel at the lower part of the fuel assembly.
  • the ratio (Awr ZAch) of the total cross-sectional area Awr of all the water inlets in the fuel assembly to the coolant passage area Ach of the fuel assembly is shown.
  • the coolant flow area A ch is roughly expressed by the following equation.
  • the coolant passage of the fuel assembly is a region outside the fuel rod 2 and the water port 3 in the channel box 7.
  • a ch D cb 2 - 7t / 4 XD f 2 x (l 0 0 - 8) -Aw r
  • L l, L 2, and L 3 are boundaries due to differences in the number of short fuel rods 2B.
  • Boundary line 1 shows a case where there are 12 short fuel rods 2B
  • boundary line L2 shows a case where there are 16 short fuel rods 2B
  • boundary line L3 shows a case where there are 20 short fuel rods 2B.
  • the boundary line L2 shown in the figure is the boundary satisfying the condition that the pressure loss is the same as that of the conventional fuel assembly.
  • each boundary line that varies depending on the number of short fuel rods 2B in the fuel assembly is expressed by (Equation 6) that includes the number n of short fuel rods as a parameter.
  • the dotted line K in Fig. 3 indicates the maximum value of the total cross-sectional area A wr of all water rods occupying eight fuel rods, and is expressed by the following equation.
  • the value corresponding to the horizontal axis of the dotted line J corresponds to the length where the effective fuel length of the short fuel rod 2B becomes 11Z24 (0.458) of that of the fuel rod 2A.
  • short fuel rods including the length of the gas plenum (formed in the fuel rods), are supported at the upper end by the fuel spacer 6 that is located at the approximate center of the fuel assembly in the axial direction. Is done.
  • the effective fuel length of the short fuel rod 2 B is to be further shortened, the effective fuel length of the short fuel rod is about 8 to 24 that of the fuel rod 2 A from the viewpoint of the flow vibration of the short fuel rod. There is a need.
  • L p ZL f needs to be equal to or greater than 11 Z 24 (Equation 4).
  • Equation 5 determined from core stability will be described.
  • Core stability The characteristic is related to the fluctuation of the core flow rate and the reactor power of the whole core after a disturbance is applied to the core. Now, it is assumed that a sine wave core flow disturbance is applied to the core. In addition, it is assumed that the fluctuation of the core flow rate in the core after the disturbance is applied is as shown in FIG. In the fluctuations in Fig. 4, the fluctuation width decreases with time, and eventually returns to a stable state.
  • the amplitude of the disturbance applied to the core is defined as y0
  • the amplitude one cycle after that is defined as yl
  • the value of ylZyO is defined as the attenuation ratio.
  • the attenuation ratio is smaller than 1, and the core returns to a stable state (steady state). In such a case, the core is said to be stable.
  • the width reduction ratio is larger than 1, the fluctuation of the core flow rate in the core increases with time, and the core becomes unstable. This is undesirable for the operation of the reactor. Therefore, it can be evaluated as stable if the reduction ratio of the core stability is smaller than 1, and unstable if it is larger than 1. Therefore, it can be evaluated as stable if it is less than 1, but in practice, the reduction ratio is
  • the inventors of the present invention have proposed a fuel assembly of 10 rows and 10 columns, in which the number of short fuel rods and the active fuel length of the short fuel rods are used as parameters to obtain a water channel with a reduction ratio of 0.8.
  • the cross-sectional area of the rod was determined, and the relationship between the number of short fuel rods, the effective fuel length, and the cross-sectional area of the water rod was clarified.
  • the average take-out burnup is 60 GW d so that the burn-up is even higher than the average take-up burnup of 45 GW d / t of the 9-row, 9-column conventional fuel assembly.
  • Figure 6 shows the analysis results.
  • the vertical and horizontal axes in FIG. 6 are the same as those in FIG.
  • Boundary line M l has 12 short fuel rods
  • boundary line M 2 has 16 short fuel rods
  • boundary line M 3 has 20 short fuel rods. It is a result in.
  • the boundary M2 is the boundary that satisfies the condition that the reduction ratio is 0.8, and the area above the boundary M2 and the boundary M2 is satisfied. Is the area where the reduction ratio is 0.8 or less. Therefore, if the total cross-sectional area of all water outlets is configured to be the upper region including the solid line M2, an average take-out burnup of 60 GW d Zt can be achieved, and allowable core stability can be achieved. Can be maintained.
  • each boundary line that depends on the number of short fuel rods 2B in the fuel assembly is expressed by (Equation 5) that includes the number n of short fuel rods as a parameter.
  • Fig. 7 shows the boundaries for pressure loss shown in Fig. 3, the boundaries for core stability shown in Fig. 6, and the boundaries J and K.
  • the boundary line M 1 indicating the minimum cross-sectional area of all water rods, which is determined by the core stability, is located above the dotted line K.
  • the total cross-sectional area of the total cross-sectional area of all the water ports which is the largest in the area occupied by the eight fuel rods in this embodiment, is equal to or larger than Total cross-sectional area is required. Therefore, with 12 short fuel rods, core stability cannot be satisfied under the condition of an average removal burnup of 60 GW d / t.
  • the hatched area indicates the relationship between (Equation 1) and (Equation 3) for the fuel assembly of 10 rows and 10 columns of the present embodiment in which 16 short fuel rods are arranged. This is an area that satisfies (Equation 6). Lp / Lf and the cross-sectional area of the water outlet 3 are set to be in this area. However, even in the case of 15 ⁇ n ⁇ 20, there are regions that satisfy (Equation 1) and (Equation 3) through (Equation 6).
  • an average take-out burnup of 6 OGW d Zt or more can be achieved, and acceptable core stability can be obtained without increasing pressure loss as compared with a conventional fuel assembly.
  • the fuel assembly of the present embodiment can be applied to an existing boiling water reactor. JP-A-5-232273 does not mention anything about achieving a burnup of 60 GW dZt or more in a fuel assembly having a fuel rod array of 10 rows and 10 columns.
  • the fuel assembly of this embodiment achieves a burnup of at least 6 OGW d Zt by satisfying the conditions of (Equation 1) to (Equation 6).
  • acceptable core stability can be obtained without increasing pressure loss as compared with a conventional fuel assembly.
  • the fuel assembly 1C of this embodiment is loaded on the core of a boiling water reactor.
  • the fuel assembly 1C is obtained by replacing the two water rods 3 of the fuel assembly 1 shown in FIG. 1 with one water rod 3C.
  • Other configurations of the present embodiment are the same as those of the fuel assembly shown in FIG.
  • the water rod 3C has a circular cross section and occupies an area where nine fuel rods can be placed.
  • the axis of the water rod 3 C is located at the corner 8 facing the control rod of the fuel assembly 1 C when loaded in the core of the boiling water reactor 8 rather than the axis of the fuel assembly 8. It is shifted to the opposite side of.
  • the corner 8 side there is a four-layer fuel rod arrangement between the water rod 3C and the channel box 7. Also, on the opposite side of the corner 8, there are three layers of fuel rod arrangement between the water inlet 3 C and the channel box 7. 1
  • Two short fuel rods 2B are arranged at a position between each corner and one from each corner in the fuel rod array of the second layer from the outside.
  • the dimensions of the inner width D eb of the channel box 7, the outer diameter D f of the fuel rod 2, the fuel rod pitch P f, and the active fuel length L f of the fuel rod 2 A are the same as those of the fuel assembly 1. .
  • the short fuel rods 2B are not arranged on the outermost layer of the fuel rod array.
  • the fuel assembly 1C calculates the effective fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3C from (Equation 1), (Equation 4), (Equation 7) to (Equation 7). 10)).
  • the conditions of (Equation 7) to (Equation 10) have been found through studies by the inventors.
  • boundary line L4 shown in FIG. 10 is a boundary line for the pressure loss when 12 short fuel rods 2B are arranged in the fuel assembly 1C other than the outermost layer of the fuel rod array.
  • boundary line M4 is a boundary line for core stability when 12 short fuel rods 2B are arranged.
  • a ch D cb 2- ? C / 4 XD f 2 x (l 0 0-9)-Aw r
  • the dotted line K1 in Fig. 10 indicates the maximum value of the total cross-sectional area Awr of the water inlet occupying the area where nine fuel rods can be arranged, and is expressed by the following equation.
  • the number of short fuel rods 2B required was in the range of 10 to 20 by the same study as in the first embodiment.
  • (Equation 8) corresponds to an area including the dotted line K1 and below the dotted line K1
  • (Equation 4) includes an area including the dotted line J and to the right of the dotted line J.
  • the hatched area in FIG. In the case where the short fuel rods 2B are arranged as shown in FIG. 9, this is an area that satisfies (Equation 10) from (Equation 1), (Equation 4) and (Equation 8).
  • LpZLf and the cross-sectional area of water rod 3 are set to be in this area.
  • (Equation 7) that is, when 10 ⁇ n ⁇ 20, (Equation 1), (Equation 4) and (Equation 8) satisfy (Equation 10).
  • the same effects as in the first embodiment can be obtained.
  • the short fuel rods are not arranged in the outermost layer, they may be arranged differently from those in FIG. 9 or may be the fuel assembly 1D shown in FIG.
  • the fuel assembly 1D is obtained by replacing the water port head 3C in the fuel assembly 1C with a water port head 3D having a rectangular cross section.
  • Fuel assembly 1E replaces the two water rods 3 in fuel assembly 1 (Fig. 1) with three water rods 3E.
  • the three water rods 3E are located on another diagonal orthogonal to the diagonal to the corner 8 facing the control rod of the fuel assembly 1E, and are adjacent to each other.
  • the middle water outlet pad 3E is also arranged diagonally to the corner part 8. That is, the one water port 3E is located on the axis of the fuel assembly 1E.
  • the three water rods 3E occupy an area where ten fuel rods 2 can be placed.
  • the outer diameter of water rod 3E is smaller than the outer diameter of water rod 3 (Fig. 1). 10 short fuel rods 2B are arranged. Eight of the short fuel rods 2B are arranged in the fuel rod array of the second layer from the outside. The remaining two short fuel rods 2B are arranged at each corner of the fuel rod array in the fourth layer from the outside. 2 layers In the eye fuel rod arrangement, short fuel rods 2B are arranged at each corner.
  • the dimensions of the inner width D cb of the channel box 7, the outer diameter D f of the fuel rod 2, the fuel rod pitch P i, and the active fuel length L f of the fuel rod 2 A of the fuel assembly 1 in the present embodiment are as follows. Same as each. In this embodiment, the short fuel rods 2B are not arranged in the outermost layer of the fuel rod array.
  • the fuel assembly 1E calculates the active fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3E from (Equation 1), (Equation 4), and (Equation 11) as ( It is configured to satisfy the condition of Equation 14).
  • the conditions from (Equation 11) to (Equation 14) were found by the inventors' studies.
  • FIG. 13 An example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1E of the present embodiment is shown in Fig. 13.
  • a boundary line L5 shown in FIG. 13 is a boundary line for the pressure loss when 10 short fuel rods 2B are arranged in the fuel assembly 1E except for the outermost layer of the fuel rod array.
  • a boundary line M5 is a boundary line for core stability when ten short fuel rods 2B are similarly arranged.
  • a ch D cb 2 - 7c / 4 x D f 2 x (l 0 0 - 1 0) - A wr
  • the dotted line K2 in Fig. 13 indicates the maximum value of the total cross-sectional area Awr of the water mouth occupying the area where 10 fuel rods can be arranged, and is expressed by the following equation.
  • the number of short fuel rods 2B required was in the range of 9 to 20 by the same study as in the first embodiment.
  • (Equation 12) corresponds to the area including the dotted line K1 and below the dotted line K2, and (Equation 4) corresponds to the area including the dotted line J and to the right of the dotted line J. Applicable.
  • the hatched area is based on (Equation 1), (Equation 4) and (Equation 12) when the ten short fuel rods 2B are arranged as shown in FIG. This is an area that satisfies (Equation 14).
  • LpZLf and the cross-sectional area of the water mouth pad 3 are set so as to be in this area. However, even when (Equation 11) is satisfied, that is, when 10 ⁇ n ⁇ 20, (Equation 14) is satisfied from (Equation 1), (Equation 4) and (Equation 12).
  • Each area exists.
  • the same effects as in the first embodiment can be obtained.
  • the short fuel rods are not arranged in the outermost layer, they may be arranged differently from those in FIG. 12 or may be a fuel assembly 1F shown in FIG.
  • the fuel assembly 1F is obtained by replacing the three water inlets 3E in the fuel assembly 1E with a single water inlet 3F.
  • Water rod 3F is located at the same position as three water rods 3C.
  • the 1 G fuel assemblies are loaded into the core of a boiling water reactor.
  • the fuel assembly 1G has a configuration in which the arrangement of the short fuel rods 2B is changed in the fuel assembly 1 shown in FIG. That is, the short fuel rods 2B are not arranged in the fuel rod array of the second layer from the outside, but are arranged in the outermost fuel rod array. In the outermost layer, two short fuel rods 2B are arranged adjacent to each other at the center of each side.
  • Other configurations of the fuel assembly 1G are the same as those of the fuel assembly 1.
  • the dimensions of the inner width D cb of the channel box 7, the outer diameter D f of the fuel rod 2, the fuel rod pitch P f, and the active fuel length L f of the fuel rod 2 A are the same as those of the fuel assembly 1. is there.
  • the fuel assembly 1G calculates the active fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3 by (Equation 1), (Equation 3), (Equation 4), and (Equation 6). ), (Equation 11) and (Equation 15).
  • Equation 1 the active fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3 by (Equation 1), (Equation 3), (Equation 4), and (Equation 6). ), (Equation 11) and (Equation 15).
  • FIG. 16 an example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1 G of the present example is shown in FIG. 16.
  • the boundary line L 6 shown in FIG. 16 is the boundary line for the pressure loss when 12 short fuel rods 2 B are arranged in the fuel assembly 1 G including the inside of the outermost fuel rod array.
  • boundary line M 6 is a boundary line for core stability when 12 short fuel rods 2 B are arranged.
  • all the short fuel rods 2B are arranged at the position where the effect of improving the coefficient of pond is large, that is, at the position adjacent to the outermost layer of the fuel rod arrangement and the water port, conditions for the core stability are required.
  • Equation 15 is different from the condition (Equation 5) for core stability in Example 1. With the same core stability, the total cross-sectional area of the water rod 3 in this embodiment is smaller than that of the first embodiment.
  • the condition (Equation 6) determined from the pressure loss in this embodiment is as follows: The arrangement is the same as that of the first embodiment, without being affected by the arrangement of the first embodiment.
  • the upper limit value of Awr Ach is the value indicated by (Equation 23) as in the first embodiment.
  • the number of short fuel rods 2B required was in the range of 9 to 20 by the same study as in the first embodiment.
  • the hatched areas are (Equation 1), (Equation 3), (Equation 4), and (Equation 1) when the two short fuel rods 2B are arranged as shown in FIG. This is an area that satisfies Equations 6) and 15).
  • Lp / Lf and the cross-sectional area of water rod 3 are set to be in this area.
  • (Equation 1 1) is satisfied, that is, when 10 ⁇ n ⁇ 20, (Equation 1), (Equation 3), (Equation 4), (Equation 6) and (Equation 6)
  • Equation 15 There are regions that satisfy Equation 15).
  • the void coefficient is reduced more than twice as compared with the case where the short fuel rods 2B are arranged in the fuel rod arrangement of the second layer from the outside.
  • the rate of decrease of the poid coefficient becomes the largest.
  • both the reactivity loss and the local power peaking of the short fuel rods 2B arranged at the corners increase. Therefore, it is necessary to avoid arranging the short fuel rod 2B at the corner.
  • the position in the outermost fuel rod array (specifically, each side of the outermost layer) intersects with the fuel rod array in the row or column in which each water outlet pad 3 is arranged.
  • the same effects as those of the first embodiment can be obtained, and The number can be reduced. In addition, reactivity loss and local output peaking can be reduced.
  • the fuel assembly 1H shown in the figure may be used.
  • the fuel assembly 1H is obtained by replacing the water port 3 in the fuel assembly 1G with a water rod 3A having a rectangular cross section.
  • the two water rods 3 A are arranged at the same position as the two water rods 3.
  • Fuel assembly 1 I is loaded into the core of a boiling water reactor.
  • the fuel assembly 1I has a configuration in which the arrangement of the short fuel rods 2B is changed in the fuel assembly 1C shown in FIG.
  • Other configurations of the fuel assembly 1I are the same as those of the fuel assembly 1C.
  • the arrangement of the water rod 3 C of the fuel assembly 1 I is the same as that of the fuel assembly 1 C.
  • This embodiment is provided with 12 short fuel rods 2B. These short fuel rods 2B are not arranged in the fuel rod array of the second layer from the outside.
  • the eight short fuel rods 2B are arranged in the outermost fuel rod array, and two fuel rods 2B are arranged adjacent to each other at the center of each side of the fuel rod array.
  • the remaining four short fuel rods 2 B are located at the corner part 8 on the side facing the control rods with the fuel assembly 1 I loaded in the core of the boiling water reactor.
  • the fuel rods are arranged in the fuel rod array of the third layer, and are arranged in the fuel rod array of the third layer from the outside on the side opposite to the corner part 8.
  • These four short fuel rods 2B are all adjacent to the water inlet 3C.
  • the dimensions of the inner width D cb of the channel box 7, the outer diameter D f of the fuel rod 2, the fuel rod pitch P f, and the active fuel length L f of the fuel rod 2 A are as follows. Same as each of body 1.
  • the fuel assembly 1 I calculates the active fuel length L p of the short fuel rod 2 B and the total cross-sectional area A wr of the water rod 3 by (Equation 1), (Equation 4), (Equation 8), (Equation 10). ), (Equation 16) and (Equation 17).
  • the conditions represented by these formulas have been found by the inventors' studies.
  • FIG. 1 an example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1I of the present embodiment is shown in FIG.
  • the boundary line L7 shown in Fig. 19 is the boundary line for the pressure loss when 12 short fuel rods 2B are arranged in the fuel assembly 1I including the inside of the outermost fuel rod array. .
  • boundary line M7 is a boundary line for core stability when 12 short fuel rods 2B are arranged.
  • all the short fuel rods 2B are arranged at positions where the effect of improving the coefficient of pond is large, that is, at positions in the outermost layer of the fuel rod array and at positions adjacent to the water inlet.
  • the condition (Equation 17) for core stability is different from the condition (Equation 9) for core stability in Example 2. If the core stability is the same, the total cross-sectional area of the water inlet 3C in this embodiment is smaller than that of the second embodiment.
  • the condition (Equation 10) determined from the pressure loss in the present embodiment is the same as that in Embodiment 2 without being affected by the arrangement of the short fuel rods.
  • the upper limit of Awr ZA ch is the value indicated by (Equation 27) as in the second embodiment. In the present embodiment, the number of short fuel rods 2B required was in the range of 8 to 20 by the same study as in the first embodiment.
  • the hatched areas indicate (Equation 1), (Equation 4), (Equation 8), and (Equation 8) when the two short fuel rods 2B are arranged as shown in FIG. This is a region that satisfies (10) and (17).
  • the cross-sectional area of LpZLf and the water rod 3C is set to be in this area.
  • (Equation 16) is satisfied, that is, when 8 ⁇ n ⁇ 20, (Equation 1), (Equation 4), (Equation 8), (Equation 10), and (Equation 1)
  • the same effects as in the fourth embodiment can be obtained.
  • the fuel assembly 1J shown in FIG. 20 may be used. Fuel assembly 1J is obtained by replacing water port 3C in fuel assembly 1I with water port 3D having a rectangular cross section. Water rod 3D is arranged at the same position as water rod 3C.
  • the 1 K fuel assemblies are loaded into the core of a boiling water reactor.
  • the fuel assembly 1K has a configuration in which the arrangement of the short fuel rods 2B is changed in the fuel assembly 1E shown in FIG.
  • Other configurations of the fuel assembly 1K are the same as those of the fuel assembly 1E.
  • the layout of the water rod 3E of the fuel assembly 1K is the same as that of the fuel assembly 1E.
  • This embodiment is provided with 10 short fuel rods 2B. These short fuel rods 2B are not arranged in the fuel rod array of the second layer from the outside.
  • the eight short fuel rods 2B are arranged in the outermost fuel rod array similarly to the fourth embodiment, and two fuel rods 2B are arranged adjacent to each other at the center of each side of the fuel rod array. I have.
  • the remaining two short fuel rods 2 B are arranged in the fourth-layer fuel rod array from the outside, and both are adjacent to the water port 3 E.
  • Inner width D eb tea down channel box 7, the outer diameter of the fuel rods 2 D f: the dimensions of the fuel rod pitch P f, and the fuel rod 2 A fuel effective length L f is the same as defined in the fuel assembly 1 .
  • the fuel assembly IK calculates the active fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3 by (Equation 1), (Equation 4), (Equation 12), (Equation 14) ), (Equation 18) and (Equation 19).
  • the conditions represented by these formulas have been found by the inventors' studies.
  • FIG. 1 an example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1 K of the present embodiment is shown in FIG.
  • the boundary line L8 shown in Fig. 22 is the boundary line for the pressure loss when 10 short fuel rods 2B are arranged in 1K of the fuel assembly including the inside of the outermost fuel rod array. is there.
  • boundary line M8 is a boundary line for core stability when 12 short fuel rods 2B are arranged.
  • the core The condition for stability (Equation 19) is different from the condition for core stability in Example 3 (Equation 13). If the core stability is the same, the total cross-sectional area of the water head 3C in this embodiment is smaller than that of the second embodiment.
  • the condition (Equation 14) determined from the pressure loss in this embodiment is the same as that in Embodiment 3 without being affected by the arrangement of the short fuel rods.
  • the upper limit of Awr / Ach is the value indicated by (Equation 31) as in the third embodiment. In the present embodiment, the number of short fuel rods 2B required was in the range of 7 to 20 by the same study as in the first embodiment.
  • the hatched areas indicate (Equation 1), (Equation 4), (Equation 1 2), and (Equation 1) when the ten short fuel rods 2B are arranged as shown in FIG.
  • This is an area that satisfies (Equation 14) and (Equation 19).
  • the cross-sectional area of LpZLf and water rod 3E is set to be in this area.
  • (Equation 1 8) is satisfied, that is, if 7 ⁇ n ⁇ 20
  • the same effects as in the fourth embodiment can be obtained.
  • the fuel assembly 1 L shown in Fig. 2 may be used.
  • the fuel assembly 1L is obtained by replacing the water port 3E in the fuel assembly 1K with a water rod 3F having a rectangular cross section. Water rod 3F is located at the same position as water rod 3E.
  • the fuel assembly of the present invention is convenient for loading into the core of a boiling water reactor.

Abstract

A fuel assembly comprising a plurality of first fuel rods, a plurality of second fuel rods having a length smaller than that of the first fuel rods and not provided in the outermost layer of a fuel rod array, and two water rods provided in a region in which eight fuel rods can be arranged, the fuel assembly being formed so as to satisfy the relation shown by the following expressions in which Awr represents the sum of cross-sectional areas of the water rods, Ach a cross-sectional area of a coolant flow passage in a lower portion of the fuel assembly, Lf an effective fuel length of the first fuel rods, n and Lp the number and an effective fuel length respectively of the second fuel rods, and B(Gwd/t) an average burn-up. B≥60; 15≤n≤20(n is an integer); Awr/Ach≤0.149; Lp/Lf≤11/24; Awr/Ach≥(3.00 x 10-4x n2+ 6.00 x 10-4 x n - 1.2 x 10-2) x (Lp/Lf - 1) + 1.75 x 10-1; Awr/Ach≤(8.63 x 10-4 x n2 - 6.09 x 10-2 x n + 1.33 x 10-1) x (Lp/Lf - 8.32 x 10-1).

Description

明 細 書  Specification
燃料集合体 技術分野  Fuel assembly technology
本発明は、 燃料集合体に係り 、 特に、 沸騰水型原子炉に適用するのに 好適な、 1 0行 1 0列に配置された複数の燃料棒を有する燃料集合体に 関する。 背景技術  The present invention relates to a fuel assembly, and more particularly to a fuel assembly having a plurality of fuel rods arranged in 10 rows and 10 columns, which is suitable for application to a boiling water reactor. Background art
近年、 ウラン資源の有効利用、 及び使用済み燃料集合体の発生量低減 の観点から、 燃料集合体の高燃焼度化が望まれている。 高燃焼度化のた めには、 燃料集合体中の核***性物質の平均濃縮度を高める ことが必要 となる。 しかし、 濃縮度の増加は、 ポイ ド変化に伴う反応度変化が増大 するため、 ボイ ド係数の絶対値が増大し、 炉心安定性が悪化する。 炉心 安定性は、 燃料集合体内の減速材割合 （減速材対燃料比） を増大する こ とによ って改善される。  In recent years, from the viewpoint of effective use of uranium resources and reduction of the amount of spent fuel assemblies, it has been desired to increase the burnup of the fuel assemblies. For higher burnup, it is necessary to increase the average enrichment of fissile material in the fuel assembly. However, as the enrichment increases, the reactivity change accompanying the poison change increases, so that the absolute value of the void coefficient increases and the core stability deteriorates. Core stability is improved by increasing the moderator ratio (moderator to fuel ratio) in the fuel assembly.
このよ う に、 核***性物質を効率的に反応させ、 沸騰水型原子炉の核 熱水力安定性を保っためには、 核***性物質の濃度の増加に伴って燃料 集合体内の減速材の割合も増大させる必要がある。  As described above, in order to efficiently react fissile material and to maintain nuclear thermo-hydraulic stability of the boiling water reactor, the moderator in the fuel assembly is increased with the increase in the concentration of fissile material. The proportion also needs to be increased.
特開平 7— 234293 号公報は、 燃料棒を 9行 9列に配置し、 4 5 G W d Z t の燃焼度を得る ことができる燃料集合体を記載している。 この燃料 集合体は、 横断面の中央部に 7 本の燃料棒が配置可能な領域に 2本の太 径水口 ッ ドを配置すると共に、 他の燃料棒よ リ軸方向の長さが短い 8本 の短尺燃料棒を配置している。 これらの短尺燃料棒は、 燃料集合体のポ ィ ド係数を改善する。 更に、 短尺燃料棒の使用は、 燃料集合体の上部の 気液二相流領域において冷却水流路面積を増加させるので、 燃料集合体 の圧力損失を低下させる。 燃料棒配列が 9行 9列配列以上となる燃料集 合体の多く は、 短尺燃料棒を用いている。 Japanese Patent Application Laid-Open No. 7-234293 describes a fuel assembly in which fuel rods are arranged in 9 rows and 9 columns and a burnup of 45 GW d Zt can be obtained. In this fuel assembly, two large-diameter water inlets are placed in the area where seven fuel rods can be placed at the center of the cross section, and the length in the axial direction is shorter than the other fuel rods. The book has short fuel rods. These short fuel rods improve the pod coefficient of the fuel assembly. In addition, the use of short fuel rods Since the area of the cooling water passage is increased in the gas-liquid two-phase flow region, the pressure loss of the fuel assembly is reduced. Many fuel assemblies with a fuel rod array of 9 rows and 9 columns or more use short fuel rods.
また、 特開平 5— 232273 号公報は、 1 0行 1 0列の燃料棒配列を有す る燃料集合体を記載する。 この燃料集合体は、 中性子減速効果を促進し てボイ ド係数の改善効果が大きく なるよう に非沸騰水領域 （水口ッ ド， ギャップ水領域） に隣接させて短尺燃料棒を配置している。 発明の開示  Japanese Patent Application Laid-Open No. 5-232273 describes a fuel assembly having a fuel rod array of 10 rows and 10 columns. In this fuel assembly, short fuel rods are arranged adjacent to the non-boiling water region (water inlet, gap water region) so that the neutron moderating effect is promoted and the effect of improving the void coefficient is increased. Disclosure of the invention
本発明の目的は、 更に高燃焼度化を図り、 従来の燃料集合体よ りも圧 力損失を増加させることなく 、 許容される炉心安定性を得ることができ る燃料集合体を提供することにある。  An object of the present invention is to provide a fuel assembly capable of achieving higher core burnup and achieving acceptable core stability without increasing pressure loss as compared with conventional fuel assemblies. It is in.
上記目的を達成する第 1発明の特徴は、 複数の第 1燃料棒、 及び前記 第 1燃料棒よ りも長さが短い複数の第 2燃料棒を有し、 これらの燃料棒 が 1 0行 1 0列の燃料棒配列内に配置され、 8本の燃料棒が配置可能な 領域を占有する複数の水ロッ ドを備え、 前記第 2燃料棒が最外層の燃料 棒配列内に配置されていない燃料集合体であって、 前記水口ッ ドの横断 面積の総和を Aw r ， 前記燃料集合体下部での冷却材流路の横断面積を A c h , 前記第 1燃料棒の燃料有効長を L f ， 前記第 2燃料棒の本数を η , 前記第 2燃料棒の燃料有効長を L p、 及び平均燃焼度を B ( GW d / t ) と したとき、 以下の式に示された関係を満足するように構成する , B > 6 0 … （数 1 ) A feature of the first invention to achieve the above object is that the first invention has a plurality of first fuel rods and a plurality of second fuel rods shorter in length than the first fuel rods. A plurality of water rods are arranged in a row of 10 fuel rods and occupy an area where eight fuel rods can be arranged, and the second fuel rod is arranged in an outermost fuel rod array. In the fuel assembly, the sum of the cross-sectional areas of the water port is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach, and the active fuel length of the first fuel rod is L. f, the number of the second fuel rods is η, the active fuel length of the second fuel rods is L p, and the average burnup is B (GW d / t). Construct to satisfy, B> 6 0… (Equation 1)
1 5≤ n≤ 2 0 ( n ： 整数） … （数 2 )1 5≤ n≤ 2 0 (n: integer)… (number 2)
Aw r /A c h≤ 0. 1 4 9 … （数 3 )Aw r / A c h≤ 0.1 4 9… (Equation 3)
L p / L f > l 1 / 2 4 … （数 4 ) Aw r /A c h ≥ ( 3. 0 0 X 1 0— 4 X n 2 + 6.0 0 x 1 0一4 L p / L f> l 1/2 4… (Equation 4) Aw r / A ch ≥ (3. 0 0 X 1 0- 4 X n 2 + 6.0 0 x 1 0 one 4
X n — 1. 2 X 1 0— 2) X (L pノ L f 一 1 ) + 1. 7 5 X 1 0-】 … （数 5 )X n — 1. 2 X 1 0 — 2 ) X (L p no L f 1 1) + 1.75 X 1 0-
Aw r /A c h ≤ ( 8. 6 3 X 1 0 ~ X n 2 - 6. 0 9 X 1 0 - 2 X n Aw r / A ch ≤ (8. 6 3 X 1 0 ~ X n 2 - 6. 0 9 X 1 0 - 2 X n
+ 1. 3 3 X 1 0 -1) X (L p / L f - 8. 3 2 X 1 0 -1 ) … （数 6 ) 上記の各式の条件を満足した本発明は、 燃焼度を更に増加させること ができ、 従来の燃料集合体よ りも圧力損失を増加させることなく 、 許容 される炉心安定性を得ることができる。 + 1. 3 3 X 1 0 - 1) X (L p / L f - 8. 3 2 X 1 0 - 1) ... ( 6) The present invention satisfies the respective expressions of the above conditions is the burnup It can be further increased, and acceptable core stability can be obtained without increasing the pressure loss as compared with the conventional fuel assembly.
上記目的を達成する第 2発明の特徴は、 複数の第 1燃料棒、 及び前記 第 1燃料棒よ リも長さが短い複数の第 2燃料棒を有し、 これらの燃料棒 が 1 0行 1 0列の燃料棒配列内に配置され、 9本の燃料棒が配置可能な 領域を占有する複数の水口ッ ドを備え、 前記第 2燃料棒が最外層の燃料 棒配列内に配置されていない燃料集合体であって、 前記水口ッ ドの横断 面積の総和を Aw r ， 前記燃料集合体下部での冷却材流路の横断面積を A c h，前記第 1燃料棒の燃料有効長を L f ，前記第 2燃料棒の本数を η , 前記第 2燃料棒の燃料有効長を L p、 及び平均燃焼度を B (GW d Z t ) と したとき、 以下の式に示された関係を満足するよう に構成する。  A feature of the second invention that achieves the above object is that it has a plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods, and these fuel rods have 10 rows. A plurality of water inlets occupying an area where nine fuel rods can be arranged are arranged in a 10-row fuel rod array, and the second fuel rod is arranged in an outermost fuel rod array. A fuel assembly, wherein the sum of the cross-sectional areas of the water port is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach, and the active fuel length of the first fuel rod is L. f, the number of the second fuel rods is η, the active fuel length of the second fuel rods is L p, and the average burnup is B (GW d Z t). Configure to satisfy.
B > 6 0 … （数 1 ) B> 60… (Equation 1)
1 0≤ n≤ 2 0 ( n : 整数） … （数 7 )1 0≤n≤2 0 (n: integer)… (Equation 7)
A r /A c h≤ 0. 1 6 9 … （数 8 )A r / A c h ≤ 0.16 9… (Equation 8)
L p / L f l 1 / 2 4 … （数 4 )L p / L f l 1/2 4… (Equation 4)
Aw r /A c h > ( 2. 6 5 X 1 0- 4 X n 2 + 2. 1 5 X 1 0— 3 X n Aw r / A ch> (2. 6 5 X 1 0- 4 X n 2 + 2. 1 5 X 1 0- 3 X n
- 1. 9 6 1 0 "2) X (L p / L f - 1 ) -1.96 1 0 " 2 ) X (L p / L f-1)
+ 1. 6 8 X 1 0—】 … （数 9 ) Aw r /A c h ≤ ( 7. 1 X 1 0 "4 X n 2 - 5. 6 3 X 1 0— 2 X n + 1. 6 8 X 1 0—]… (Equation 9) Aw r / A ch ≤ (7. 1 X 1 0 "4 X n 2 - 5. 6 3 X 1 0- 2 X n
+ 8. 8 X 1 0 "2) x (L p / L f - 8. 5 2 + 8.8 X 10 " 2 ) x (L p / L f-8.5 2
X 1 0 _つ … （数 1 0 ) 第 2発明も、 第 1発明と同じ効果を得ることができる。  X 10 0 ... (Equation 10) The second invention can also obtain the same effect as the first invention.
上記の目的を達成する第 3発明の特徴は、 複数の第 1燃料棒、 及び前 記第 1燃料棒よ りも長さが短い複数の第 2燃料棒を有し、 これらの燃料 棒が 1 0行 1 0列の燃料棒配列内に配置され、 1 0本の燃料棒が配置可 能な領域を占有する複数の水ロッ ドを備え、 前記第 2燃料棒が最外層の 燃料棒配列内に配置されていない燃料集合体であって、 前記水口ッ ドの 横断面積の総和を Aw r ， 前記燃料集合体下部での冷却材流路の横断面 積を A c h， 前記第 1燃料棒の燃料有効長を L f ， 前記第 2燃料棒の本 数を n， 前記第 2燃料棒の燃料有効長を L p、 及び平均燃焼度を B (GWd / t ) と したとき、 以下の式に示された関係を満足するよう に構成する。  The feature of the third invention that achieves the above object is that it has a plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rod, and these fuel rods have one or more fuel rods. A plurality of water rods are arranged in a fuel rod array of 0 rows and 10 columns, and occupy an area where 10 fuel rods can be arranged, and the second fuel rods are arranged in an outermost fuel rod array. A fuel assembly that is not disposed in the fuel assembly, wherein the sum of the cross-sectional areas of the water inlets is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach, When the active fuel length is Lf, the number of the second fuel rods is n, the active fuel length of the second fuel rod is Lp, and the average burnup is B (GWd / t), Configure to satisfy the indicated relationship.
B 6 0 … （数 1 ) B 6 0… (Equation 1)
9 ≤ n < 2 0 ( n ： 整数） … （数 1 1 )9 ≤ n <2 0 (n: integer)… (number 1 1)
Aw r /A c h≤ 0. 1 9 0 … （数 1 2 )Aw r / A c h ≤ 0.19 0… (Equation 1 2)
L p / L f 1 1 / 2 … （数 4 )L p / L f 1 1/2… (Equation 4)
A r /A c h≥ ( 2. 3 1 X 1 0 1 X n 2 + 3. 6 9 X 1 0一3 X n A r / A ch≥ (2. 3 1 X 1 0 1 X n 2 + 3. 6 9 X 1 0 one 3 X n
- 2. 7 1 X 1 0 ：) X ( L p / L f - 1 )  -2.71X10:) X (Lp / Lf-1)
+ 1. 6 0 X 1 0 … （数 1 3 ) + 1.6 0 X 10 ... (number 13)
Aw r /A c h≤ ( 6. 1 8 X 1 0 1 X n 2 - 5. 1 8 X 1 0一2 X n Aw r / A ch≤ (6. 1 8 X 1 0 1 X n 2 - 5. 1 8 X 1 0 one 2 X n
+ 4. 1 X 1 0 :) x (L p / L f - 8. 7 2 + 4. 1 X 1 0:) x (L p / L f - 8. 7 2
X 1 0 -リ … （数 1 4 ) 第 3発明も、 第 1発明と同じ効果を得るこ とができる。  X 10 -R (Equation 14) The third invention can also obtain the same effect as the first invention.
上記目的を達成する第 4発明の特徴は、 複数の第 1燃料棒、 及び前記 第 1燃料棒よ りも長さが短い複数の第 2燃料棒を有し、 これらの燃料棒 が 1 0行 1 0列の燃料棒配列内に配置され、 8本の燃料棒が配置可能な 領域を占有する複数の水ロッ ドを備え、 前記第 2燃料棒が、 最外層の燃 料棒配列内の位置及び前記水口ッ ドに隣接した位置の両方、 及び最外層 の燃料棒配列内の位置のみ、 のいずれかに配置された燃料集合体であつ て、 前記水ロ ッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部での 冷却材流路の横断面積を A c h， 前記第 1燃料棒の燃料有効長を L f ， 前記第 2燃料棒の本数を n， 前記第 2燃料棒の燃料有効長を L p、 及び 平均燃焼度を B ( GW d / t ) と したとき、 以下の式に示された関係を 満足するよう に構成する。 The features of the fourth invention for achieving the above object are a plurality of first fuel rods, It has a plurality of second fuel rods shorter in length than the first fuel rods, and these fuel rods are arranged in a fuel rod array of 10 rows and 10 columns, and eight fuel rods can be arranged A plurality of water rods occupying an area, wherein the second fuel rods are located both in the outermost fuel rod array and adjacent to the water port array, and in the outermost fuel rod array. A fuel assembly arranged at any one of the following positions, wherein the sum of the cross-sectional areas of the water rod is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach, When the active fuel length of the first fuel rod is L f, the number of the second fuel rods is n, the active fuel length of the second fuel rod is L p, and the average burnup is B (GW d / t). , So as to satisfy the relationship shown in the following equation.
B > 6 0 … （数 1 ) B> 60… (Equation 1)
9 ≤ n≤ 2 0 ( n ： 整数） … （数 1 1 )9 ≤ n ≤ 2 0 (n: integer)… (number 1 1)
Aw r /A c h≤ 0. 1 9 … （数 3 )Aw r / A c h ≤ 0.1 9… (Equation 3)
L p / L f 1 1 / 2 … （数 4 )L p / L f 1 1/2… (Equation 4)
Aw r /A c h≥ ( 3. 0 0 X 1 0 X n 2 + 6. 0 0 x l 0 "4 x n Aw r / A ch≥ (3. 0 0 X 1 0 X n 2 + 6. 0 0 xl 0 "4 xn
+ 6. 8 0 X 1 0 ) X ( L p / L 1 )  + 6.80X10) X (Lp / L1)
+ 1. 7 5 X 1 0 • (数 1 5 ) + 1.75 X 1 0 • (Number 1 5)
Aw r /A c h≤ ( 8. 6 3 X 1 0 X n 2 - 6. 0 9 x l 0"2 X n Aw r / A ch≤ (8. 6 3 X 1 0 X n 2 - 6. 0 9 xl 0 "2 X n
+ 1. 3 3 X 1 O- iL p / L f - e. S 2 X 1 0 _リ … （数 6 ) 第 4発明も、 第 1発明と同じ効果を得ることができる。  + 1.33X1O-iLp / Lf-e. S2X10_? (Equation 6) The fourth invention can also obtain the same effect as the first invention.
上記目的を達成する第 5発明の特徴は、 複数の第 1燃料棒、 及び前記 第 1燃料棒よ りも長さが短い複数の第 2燃料棒を有し、 これらの燃料棒 が 1 0行 1 0列の燃料棒配列内に配置され、 9本の燃料棒が配置可能な 領域を占有する複数の水ロッ ドを備え、 前記第 2燃料棒が、 最外層の燃 料棒配列内の位置及び前記水口ッ ドに隣接した位置の両方、 及び最外層 の燃料棒配列内の位置のみ、 のいずれかに配置された燃料集合体であつ て、 前記水ロ ッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部での 冷却材流路の横断面積を A c h， 前記第 1燃料棒の燃料有効長を L f , 前記第 2燃料棒の本数を η， 前記第 2燃料棒の燃料有効長を L ρ、 及び 平均燃焼度を B ( GW d Z t ) と したとき、 以下の式に示された関係を 満足するよう に構成する。 A feature of the fifth invention that achieves the above object is that the fifth invention has a plurality of first fuel rods and a plurality of second fuel rods shorter in length than the first fuel rods. A plurality of water rods are arranged in a 10-row fuel rod array, and occupy an area where nine fuel rods can be placed, and the second fuel rod has an outermost fuel rod. A fuel assembly arranged at one of the position in the fuel rod array and the position adjacent to the water port, and only the position in the outermost fuel rod array, and The sum of the cross-sectional areas is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach, the active fuel length of the first fuel rods is Lf, the number of the second fuel rods is η, When the active fuel length of the second fuel rod is L ρ and the average burnup is B (GW d Z t), the configuration is such that the relationship shown in the following equation is satisfied.
B > 6 0 … （数 1 ) B> 60… (Equation 1)
8≤ n < 2 0 ( n ： 整数） … （数 1 6 ) Aw r /A c h≤ 0. 1 6 9 … （数 8 ) L p / L f > 1 1 / 2 … （数 4 ) A r / A c h ( 2. 6 5 X 1 0 X n 2+ 2. 1 5 X l O -3 X n 8≤ n <20 (n: integer)… (Equation 16) Aw r / A ch ≤ 0.169… (Equation 8) L p / L f> 1 1/2… (Equation 4) A r / A ch (2.65 X 10 X n 2 + 2.15 X l O- 3 X n
+ 6. 0 X 1 0 :) X ( L p / L f - 1 ) + 6. 0 X 1 0:) X (L p / L f - 1)
+ 1. 6 8 X 1 0 … （数 1 7 ) Aw r /A c h < ( 7.4 1 X 1 0 ' X n 2 - 5. 6 3 x l 0"2 x n +1.68 X 10… (Equation 17) Aw r / A ch <(7.4 1 X 10 'X n 2 -5.6 3 xl 0 " 2 xn
+ 8. 8 X 1 0 :) x (L p / L f - 8. 5 2 1 0 -1 ) … （数 1 0 ) 第 5発明も、 第 1発明と同じ効果を得ることができる。 + 8. 8 X 1 0:) x (L p / L f - 8. 5 2 1 0 - 1) ... ( Equation 1 0) fifth invention can also achieve the same effect as the first invention.
上記目的を達成する第 6発明の特徴は、 複数の第 1燃料棒、 及び前記 第 1燃料棒よ リも長さが短い複数の第 2燃料棒を有し、 これらの燃料棒 が 1 0行 1 0列の燃料棒配列内に配置され、 1 0本の燃料棒が配置可能 な領域を占有する複数の水ロ ッ ドを備え、 前記第 2燃料棒が、 最外層の 燃料棒配列内の位置及び前記水口 ッ ドに隣接した位置の両方、 及び最外 層の燃料棒配列内の位置のみ、 のいずれかにて配置された燃料集合体で あって、 前記水ロッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部 での冷却材流路の横断面積を A c h， 前記第 1燃料棒の燃料有効長を L f , 前記第 2燃料棒の本数を n， 前記第 2燃料棒の燃料有効長を L p、 及び平均燃焼度を B ( GW d / t ) と したとき、 以下の式に示された関 係を満足するよう に構成する。 A feature of the sixth invention that achieves the above object is that the sixth invention has a plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods. A plurality of water rods are arranged in a 10-row fuel rod array and occupy an area where 10 fuel rods can be placed, and the second fuel rod is provided in the outermost fuel rod array. A fuel assembly arranged at any one of the position and the position adjacent to the water port, and only the position in the outermost fuel rod array, and the sum of the cross-sectional areas of the water rods Aw r, the lower part of the fuel assembly Is the cross-sectional area of the coolant flow path at A ch, the active fuel length of the first fuel rod is L f, the number of the second fuel rods is n, the active fuel length of the second fuel rod is L p, and When the average burnup is B (GWd / t), it is configured to satisfy the relationship shown in the following equation.
B 6 0 … （数 1 ) B 6 0… (Equation 1)
7 ≤ n≤ 2 0 ( n : 整数） … （数 1 8 )7 ≤ n≤ 2 0 (n: integer)… (number 1 8)
Aw r /A c h≤ 0. 1 9 0 … （数 1 2 )Aw r / A c h ≤ 0.19 0… (Equation 1 2)
L p / L f ≥ 1 1 / 2 4 … （数 4 )L p / L f ≥ 1 1/2 4… (Equation 4)
Aw r /A c h ≥ ( 2. 3 1 X 1 0 "4 X n 24- 3. 6 9 X 1 ◦ - 3 X n Aw r / A ch ≥ (2.3 1 X 1 0 " 4 X n 2 4-3.6 9 X 1 ◦- 3 X n
+ 5. 2 9 X 1 0 -2) x (L p / L f - l ) + 5. 2 9 X 1 0 - 2) x (L p / L f - l)
+ 1. 6 0 X 1 0 - 1 … （数 1 9 )+ 1. 6 0 X 1 0 - 1 ... ( number 1 9)
Aw r /A c h≤ ( 6. 1 8 x 1 0- 4 X n 2— 5. 1 8 X 1 0- 2 X n Aw r / A ch≤ (6.18 x 1 0- 4 X n 2 — 5.18 X 1 0- 2 X n
+ 4. 1 X 1 0 "2) x (L p / L f - 8. 7 2 + 4.1 X 1 0 " 2 ) x (L p / L f -8.72
X 1 0 - " … （数 1 4 ) 第 6発明も、 第 1発明と同じ効果を得ることができる。 図面の簡単な説明  X 10-"(Equation 14) The sixth invention can also achieve the same effects as the first invention.
第 1 図は本発明の好適な一実施例である燃料集合体の縦断面図、 第 2 図は第 1 図に示す燃料集合体の横断面図、 第 3図は圧力損失から決定さ れた、 短尺燃料棒 2 Bの燃料有効長 L p /燃料棒 2 Aの燃料有効長 L f と水口ッ ド総横断面積 Aw r /燃料集合体内の冷却材流路面積 A c hと の関係を示す特性図、 第 4図は安定な状態における、 安定性の指標であ る減幅比の説明図、 第 5図は不安定な状態における、 安定性の指標であ る減幅比の説明図、 第 6図は炉心安定性から決定された、 短尺燃料棒 2 Bの燃料有効長 L pノ燃料棒 2 Aの燃料有効長 L f と水口 ッ ド総横断 面積 Aw r 燃料集合体内の冷却材流路面積 A c hとの関係を示す特性 図、 第 7図は第 3図及び第 6図に示された各特性を示す特性図、 第 8図 及び第 9図は本発明の他の実施例である燃料集合体の横断面図、 第 1 0 図は第 9図の燃料集合体における、 圧力損失及び炉心安定性から決定さ れた、 短尺燃料棒 2 Bの燃料有効長 L p Z燃料棒 2 Aの燃料有効長 L f と水口ッ ド総横断面積 Aw r Z燃料集合体内の冷却材流路面積 A c hと の関係を示す特性図、 第 1 1 図及び第 1 2図は本発明の他の実施例であ る燃料集合体の横断面図、 第 1 3図は第 1 2図の燃料集合体における、 圧力損失及び炉心安定性から決定された、 短尺燃料棒 2 Bの燃料有効長 L p Z燃料棒 2 Aの燃料有効長 L f と水口ッ ド総横断面積 Aw r Z燃料 集合体内の冷却材流路面積 A c hとの関係を示す特性図、 第 1 4図及び 第 1 5図は本発明の他の実施例である燃料集合体の横断面図、 第 1 6図 は第 1 5図の燃料集合体における、 圧力損失及び炉心安定性から決定さ れた、 短尺燃料棒 2 Bの燃料有効長 L p /燃料棒 2 Aの燃料有効長 L f と水口ッ ド総横断面積 Aw r Z燃料集合体内の冷却材流路面積 A c hと の関係を示す特性図、 第 1 7図及び第 1 8図は本発明の他の実施例であ る燃料集合体の横断面図、 第 1 9図は第 1 8図の燃料集合体における、 圧力損失及び炉心安定性から決定された、 短尺燃料棒 2 Bの燃料有効長 L p /燃料棒 2 Aの燃料有効長 L f と水口 ッ ド総横断面積 Aw r /燃料 集合体内の冷却材流路面積 A c hとの関係を示す特性図、 第 2 0図及び 第 2 1 図は本発明の他の実施例である燃料集合体の横断面図、 第 2 2図 は第 2 1 図の燃料集合体における、 圧力損失及び炉心安定性から決定さ れた、 短尺燃料棒 2 Bの燃料有効長 L p Z燃料棒 2 Aの燃料有効長 L f と水ロッ ド総横断面積 Aw rノ燃料集合体内の冷却材流路面積 A c hと の関係を示す特性図、 第 2 3図は本発明の他の実施例である燃料集合体 の横断面図である。 発明を実施するための最良の形態 FIG. 1 is a longitudinal sectional view of a fuel assembly according to a preferred embodiment of the present invention, FIG. 2 is a transverse sectional view of the fuel assembly shown in FIG. 1, and FIG. 3 is determined from pressure loss. The characteristic indicating the relationship between the active fuel length Lp of the short fuel rod 2B / the active fuel length Lf of the fuel rod 2A and the total cross-sectional area Awr of the water inlet / the coolant passage area Ach in the fuel assembly Fig. 4 is an explanatory diagram of the width reduction ratio as an indicator of stability in a stable state. Fig. 5 is an explanatory diagram of the width reduction ratio as an indicator of stability in an unstable state. Fig. 6 shows the effective fuel length of the short fuel rod 2B Lp and the effective fuel length Lf of the fuel rod 2A and the total cross section of the water port determined from the core stability. Area Aw r A characteristic diagram showing the relationship with the coolant flow path area A ch in the fuel assembly, FIG. 7 is a characteristic diagram showing each characteristic shown in FIG. 3 and FIG. 6, FIG. 8 and FIG. Fig. 10 is a cross sectional view of a fuel assembly according to another embodiment of the present invention. Fig. 10 is a short fuel rod 2B determined from pressure loss and core stability in the fuel assembly of Fig. 9. Fig. 11 is a characteristic diagram showing the relationship between the active fuel length Lp Z of the fuel rod 2A and the active fuel length L f of the fuel rod 2A and the total cross-sectional area Aw r Z of the coolant passage area Ach in the fuel assembly. FIG. 12 is a cross-sectional view of a fuel assembly according to another embodiment of the present invention, and FIG. 13 is a diagram showing the fuel assembly of FIG. 12 determined from pressure loss and core stability. Characteristic diagram showing the relationship between the effective fuel length of the short fuel rod 2 B L p Z The active fuel length of the fuel rod 2 A L f and the total cross-sectional area of the water inlet Aw r Z The coolant flow path area Ach in the fuel assembly , 14 and 15 are cross-sectional views of a fuel assembly according to another embodiment of the present invention, and FIG. 16 is determined from the pressure loss and core stability of the fuel assembly of FIG. The relationship between the active fuel length Lp of the short fuel rod 2B and the active fuel length Lf of the fuel rod 2A and the total cross-sectional area of the water inlet AwrZ is shown below. FIG. 17 and FIG. 18 are cross-sectional views of a fuel assembly according to another embodiment of the present invention, and FIG. Effective fuel length of short fuel rod 2B Lp / effective fuel length of fuel rod 2A Lf and total cross-sectional area of water port Awr, determined from core stability FIG. 20 is a cross-sectional view of a fuel assembly according to another embodiment of the present invention, and FIG. 22 is a cross-sectional view of the fuel assembly of FIG. 21. , Pressure drop Effective fuel length of short fuel rod 2B Lp Z Effective fuel length Lf of fuel rod 2A and total cross-sectional area of water rod Awr FIG. 23 is a characteristic diagram showing the relationship with the area A ch, and FIG. FIG. BEST MODE FOR CARRYING OUT THE INVENTION
(実施例 1 )  (Example 1)
このよ う に、 ポイ ド係数は、 主に水ロ ッ ド面積， 短尺燃料棒の本数， 長さ、 さ らに配置に影響される。 しかしながら、 上記従来例では、 炉心 安定性へ与える短尺燃料棒本数， 長さによるボイ ド係数の影響が定量的 に評価されていない。 現行炉心へのバックフ ィ ッ トを考えると、 従来燃 料と同程度となる炉心安定性とする必要があり、 上記ボイ ド係数の評価 が十分でないと、 高燃焼度化を達成できる炉心安定性の評価 （水ロッ ド 面積， 短尺燃料棒本数， 長さ） も十分とはいえない。 さ らに、 バックフ イ ッ ト上重要である集合体の圧力損失への影響、 言い換えれば、 水口ッ ド面積， 短尺燃料棒本数， 長さが及ぼす圧力損失への影響が考慮されて いない。  In this way, the poiid coefficient is mainly affected by the water rod area, the number and length of short fuel rods, and the arrangement. However, in the above conventional example, the effect of the void coefficient on the number and length of the short fuel rods on the core stability has not been quantitatively evaluated. Considering the backfit to the current core, it is necessary to achieve core stability equivalent to that of conventional fuel.If the above void coefficient is not sufficiently evaluated, core stability that can achieve high burnup can be achieved. The evaluation (water rod area, number of short fuel rods, length) is not sufficient. In addition, the effect on the pressure loss of the aggregate, which is important for backfitting, in other words, the effects of the water inlet area, the number of short fuel rods, and the length on the pressure loss are not considered.
以下、 本発明の好適な一実施例である燃料集合体を、 第 1 図及び第 2 図を用いて説明する。 この燃料集合体 1 は、 沸騰水型原子炉の炉心に装 荷される。 燃料集合体 1 は、 燃料棒 2 を 1 0行 1 0列の正方格子状に配 置している。 燃料棒 2は、 軸方向の長さが長い燃料棒 2 A、 及び燃料棒 2 Aよ りも軸方向の長さが短い短尺燃料棒 2 Bを含んでいる。 燃料集合 体 1 の横断面中央には、 2本の水ロ ッ ド 3が配置される。 各々の水口 ッ ド 3は、 横断面が円形であって、 4本の燃料棒が配置可能な領域を占有 する大きさを有する。 2本の水ロッ ド 3は、 各々の軸心が燃料集合体 1 の 1 つの対角線上に配置される。 これらの水ロ ッ ド 3は、 燃料棒配列の 外側から 4層目以内の領域に配置され、 もう 1 つの対角線 （燃料集合体 1 が沸騰水型原子炉の炉心内に装荷された状態で制御棒に面するコーナ 一部 8 に対する対角線） に対して線対称の位置に配置される。 燃料棒 2 A及び水口 ッ ド 3 は、 上端部が上部タィ プレー 卜 4 に保持され、 下端 部が下部タイ プレー ト 5 に保持される。 短尺燃料棒 2 Bは、 下端部が下 部タイ プレー ト 5 に保持される。 燃料棒 2 A , 2 B及び水口 ッ ド 3 は、 燃料スぺーサ 5 によ って相互の間に所定の間隔を保って保持される。 こ れらの燃料棒は、 上部タイ プレー ト 4 に取付けられたチャ ンネルボック ス 7 内に収納されている。 Hereinafter, a fuel assembly according to a preferred embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. This fuel assembly 1 is loaded into the core of a boiling water reactor. In the fuel assembly 1, the fuel rods 2 are arranged in a square matrix of 10 rows and 10 columns. The fuel rod 2 includes a fuel rod 2A having a longer axial length and a short fuel rod 2B having a shorter axial length than the fuel rod 2A. Two water rods 3 are arranged in the center of the cross section of the fuel assembly 1. Each water port 3 has a circular cross section and has a size occupying an area where four fuel rods can be arranged. The two water rods 3 are arranged so that each axis is on one diagonal line of the fuel assembly 1. These water rods 3 are located in the area within the fourth layer from the outside of the fuel rod array, and the other diagonal line (the fuel assembly 1 is controlled while loaded in the core of a boiling water reactor) Corner facing rod (Diagonal line to part 8). The upper end of the fuel rod 2 A and the water port 3 is held by the upper plate 4, and the lower end is held by the lower plate 5. The lower end of the short fuel rod 2 B is held by the lower tie plate 5. The fuel rods 2A, 2B and the water port 3 are held at a predetermined distance from each other by a fuel spacer 5. These fuel rods are housed in a channel box 7 mounted on the upper tie plate 4.
1 6 本の短尺燃料棒 2 Bのう ち 1 2 本は、 燃料棒配列の外側から 2層 目に配置されている。 2層目の燃料棒配列において、 1 2本の短尺燃料 棒 2 Bは、 各コーナ一及び各コーナ一から 1 本間を置いた位置にそれぞ れ配置される。 残り の 4本の短尺燃料棒 2 Bは、 水ロ ッ ド 3 に隣接して 配置される。 本実施例において、 チャ ンネルボックス 7 の内幅 D c b は 約 1 3 4 ππιι、 燃料棒 2 A及び 2 Bの外径 D f は 1 0 . 2 6 nun 、 燃料棒ピ ツチ P f は 1 2 . 9 5 mm、 燃料棒 2 Aの燃料有効長 L f は約 3 , 7 mであ る。 本実施例は、 短尺燃料棒 2 B を燃料棒配列の最外層に配置していな い。  Of the sixteen short fuel rods 2 B, one or two of them are arranged in the second layer from the outside of the fuel rod arrangement. In the fuel rod array of the second layer, the 12 short fuel rods 2B are arranged at each corner and at a position spaced one from each corner. The remaining four short fuel rods 2 B are arranged adjacent to the water rod 3. In this embodiment, the inner width D cb of the channel box 7 is about 1334 ππιι, the outer diameters D f of the fuel rods 2A and 2B are 10.26 nun, and the fuel rod pitch P f is 12 .95 mm, the effective fuel length L f of the fuel rod 2 A is about 3.7 m. In this embodiment, the short fuel rods 2B are not arranged on the outermost layer of the fuel rod array.
本実施例の燃料集合体 1 は、 短尺燃料棒 1 Bの燃料有効長 L p ， 水口 ッ ド 2 の総横断面積 A w r を、 （数 1 ) から （数 6 ) の条件を満たすよ う構成されたものである。 （数 1 ) から （数 6 ) の条件は、 発明者らの 検討によ って見出されたものである。 これらの検討結果を以下に詳細に 説明する。  The fuel assembly 1 of this embodiment is configured such that the active fuel length L p of the short fuel rod 1 B and the total cross-sectional area A wr of the water port 2 satisfy the conditions of (Equation 1) to (Equation 6). It was done. The conditions of (Equation 1) to (Equation 6) have been found through the study of the inventors. The results of these studies are described in detail below.
まず、 燃料集合体の圧力損失から決定された （数 6 ) について説明す る。 本発明者らは、 1 0行 1 0列の燃料集合体において、 短尺燃料棒の 本数， 短尺燃料棒の燃料有効長をパラメータ と して、 特開平 7— 234293 号公報に示す 9行 9列の従来の燃料集合体 （以下、 単に従来燃料集合体 という ） の圧力損失と同じ圧力損失となる水口 ッ ド 3の総横断面積を求 め、 短尺燃料棒の本数， 短尺燃料棒の燃料有効長 L p と全水口ッ ドの総 横断面積の関係を明らかにした。 第 3図にそれらの関係を示す。 第 3図 において横軸は燃料棒 2 Aの燃料有効長 L f に対する短尺燃料棒 2 Bの 燃料有効長 L p との比 （ L p Z L f ) を、 縦軸は燃料集合体下部での燃 料集合体の冷却材流路面積 A c hに対する燃料集合体内の全水口ッ ドの 総横断面積 Aw r との比 （ Aw r ZA c h ) をそれぞれ示している。 と ころで、 冷却材流路面積 A c hは、 概略、 次式で表される。 燃料集合体 の冷却材流路は、 チャ ンネルボックス 7内における、 燃料棒 2及び水口 ヅ ド 3の外側の領域である。 First, (Equation 6) determined from the pressure loss of the fuel assembly will be described. In the fuel assembly of 10 rows and 10 columns, the present inventors used the number of short fuel rods and the effective fuel length of the short fuel rods as parameters, as shown in JP-A-7-234293. Conventional fuel assemblies (hereinafter simply referred to as conventional fuel assemblies) The total cross-sectional area of the water inlet head 3 that has the same pressure loss as the pressure loss of the water outlet head 3 is determined, and the relationship between the number of short fuel rods, the active fuel length L p of the short fuel rods, and the total cross-sectional area of all water outlet heads is determined. Revealed. Figure 3 shows their relationship. In FIG. 3, the horizontal axis represents the ratio (L p ZL f) of the active fuel length L f of the fuel rod 2 A to the active fuel length L p of the short fuel rod 2 B, and the vertical axis represents the fuel at the lower part of the fuel assembly. The ratio (Awr ZAch) of the total cross-sectional area Awr of all the water inlets in the fuel assembly to the coolant passage area Ach of the fuel assembly is shown. At this point, the coolant flow area A ch is roughly expressed by the following equation. The coolant passage of the fuel assembly is a region outside the fuel rod 2 and the water port 3 in the channel box 7.
A c h = D c b 2 - 7t / 4 X D f 2 x ( l 0 0 - 8) -Aw r A ch = D cb 2 - 7t / 4 XD f 2 x (l 0 0 - 8) -Aw r
… （数 2 0 ) … (Number 20)
(数 2 0 ) に本実施例での前述の該当する数値を代入すると、 By substituting the corresponding numerical value in this embodiment into (Equation 20),
A c h = 1 0 3 5 0 - Aw r (mm2 ) … （数 2 1 ) となる。 A ch = 1 0 3 5 0-A w r (mm 2 ) ... (Equation 2 1).
また、 横軸の値が 0. 5の場合、 短尺燃料棒 2 Bの有効長が約 1.85m ( 3. 7 m X 0. 5 ) であることを意味している。 第 3図において、 L l ， L 2 , L 3は、 短尺燃料棒 2 Bの本数の違いによる境界線である。 境界 線し 1 は短尺燃料棒 2 Bが 1 2本、 境界線 L 2 は短尺燃料棒 2 Bが 1 6 本、 及び境界線 L 3は短尺燃料棒 2 Bが 2 0本の場合を示す。 短尺燃料 棒 2 Bが 1 6本の場合には、 図中に示した境界線 L 2が、 従来燃料集合 体と圧力損失が同一となる条件を満足する境界である。 なお、 短尺燃料 棒 2 Bが 1 6本の場合には、 境界線 L 2、 及び境界線 L 2 よ りも下側の 領域が、 従来燃料集合体の圧力損失よ リも大きく ならない領域である。 従って、 全水口ッ ドの総横断面積が境界線 L 2 を含む下側の領域となる ように構成すれば、 本実施例の燃料集合体の圧力損失が従来燃料集合体 のそれ以下にすることができる。 すなわち、 Aw r /A c hは、 （数 6 ) を満足すればよい。 第 3図において、 燃料集合体内の短尺燃料棒 2 Bの 本数によって異なる各境界線は、 短尺燃料棒の本数 nをパラメータと し て含む （数 6 ) で現される。 When the value on the horizontal axis is 0.5, it means that the effective length of the short fuel rod 2B is approximately 1.85m (3.7m X 0.5). In FIG. 3, L l, L 2, and L 3 are boundaries due to differences in the number of short fuel rods 2B. Boundary line 1 shows a case where there are 12 short fuel rods 2B, boundary line L2 shows a case where there are 16 short fuel rods 2B, and boundary line L3 shows a case where there are 20 short fuel rods 2B. When there are 16 short fuel rods 2B, the boundary line L2 shown in the figure is the boundary satisfying the condition that the pressure loss is the same as that of the conventional fuel assembly. When there are 16 short fuel rods 2B, the boundary line L2 and the region below the boundary line L2 are regions where the pressure loss is not larger than the pressure loss of the conventional fuel assembly. . Therefore, the total cross-sectional area of all water outlets is the lower area including boundary line L 2 With such a configuration, the pressure loss of the fuel assembly of the present embodiment can be made smaller than that of the conventional fuel assembly. That is, Awr / Ach should satisfy (Equation 6). In FIG. 3, each boundary line that varies depending on the number of short fuel rods 2B in the fuel assembly is expressed by (Equation 6) that includes the number n of short fuel rods as a parameter.
また、 第 3図内の点線 Kは、 燃料棒 8本分を占有する全水ロ ッ ドの総 横断面積 A w r の最大値を示しており、 次式で表される。  The dotted line K in Fig. 3 indicates the maximum value of the total cross-sectional area A wr of all water rods occupying eight fuel rods, and is expressed by the following equation.
A w r = P f 2 X 8 … （数 2 2 ) よって、 全水口ッ ドの総横断面積の上限値に対する Aw r ZA c hの 値は、 A wr = P f 2 X 8… (Equation 2 2) Therefore, the value of Awr rZA ch with respect to the upper limit of the total cross-sectional area of all water outlets is
Aw r /A c h = l 3 4 2 /( 1 0 3 5 0— 1 3 4 2 ) = 0. 1 9 Aw r / A c h = l 3 4 2 / (1 0 3 5 0— 1 3 4 2) = 0.19
… （数 2 3 ) となる。 従って、 Aw r ZA c hは、 0. 1 4 9 以下にしなければなら ない （数 3 ) 。 … (Equation 2 3). Therefore, Aw r ZA ch must be less than 0.149 (Equation 3).
更に、 点線 J の横軸に対応する値は、 短尺燃料棒 2 Bの燃料有効長が 燃料棒 2 Aのそれの 1 1 Z 2 4 (0. 4 5 8 ) となる長さに相当する。 こ の長さでは、 ガスプレナム （燃料棒内に形成） の長さを含めた短尺燃料 棒は、 燃料集合体の、 軸方向のほぼ中央部に配置された燃料スぺーサ 6 で上端部を支持される。 しかしながら、 短尺燃料棒 2 Bの燃料有効長を 更に短く しょう とすると、 短尺燃料棒の流動振動の観点から短尺燃料棒 の燃料有効長は、 燃料棒 2 Aのそれの 8ノ 2 4程度にする必要がある。 このよ う に短尺燃料棒 2 Bの燃料有効長を 1 1 / 2 4よ りも短く した場 合には、 ウランイ ンペン ト リ が減少しすぎ、 燃料サイクル費が悪く なる。 このため、 L p Z L f は 1 1 Z 2 4以上にする必要がある （数 4 ) 。 次に炉心安定性から決定された （数 5 ) について説明する。 炉心安定 性は、 ある外乱が炉心に加えられた後における炉心全体の炉心流量およ び原子炉出力の変動に係わる特性である。 今、 正弦波の炉心流量の外乱 が炉心に加えられたとする。 また、 外乱が加えられた後における炉心内 の炉心流量の変動が第 4図のようであったとする。 第 4図の変動では、 変動幅は時間とともに減少し、 やがて安定な状態に戻る。 Further, the value corresponding to the horizontal axis of the dotted line J corresponds to the length where the effective fuel length of the short fuel rod 2B becomes 11Z24 (0.458) of that of the fuel rod 2A. With this length, short fuel rods, including the length of the gas plenum (formed in the fuel rods), are supported at the upper end by the fuel spacer 6 that is located at the approximate center of the fuel assembly in the axial direction. Is done. However, if the effective fuel length of the short fuel rod 2 B is to be further shortened, the effective fuel length of the short fuel rod is about 8 to 24 that of the fuel rod 2 A from the viewpoint of the flow vibration of the short fuel rod. There is a need. If the active fuel length of the short fuel rods 2B is shorter than 1 1/24, the uranium inventory will decrease too much, and the fuel cycle cost will decrease. Therefore, L p ZL f needs to be equal to or greater than 11 Z 24 (Equation 4). Next, (Equation 5) determined from core stability will be described. Core stability The characteristic is related to the fluctuation of the core flow rate and the reactor power of the whole core after a disturbance is applied to the core. Now, it is assumed that a sine wave core flow disturbance is applied to the core. In addition, it is assumed that the fluctuation of the core flow rate in the core after the disturbance is applied is as shown in FIG. In the fluctuations in Fig. 4, the fluctuation width decreases with time, and eventually returns to a stable state.
こ こで、 炉心に加えられた外乱の振幅を y 0、 その 1周期後の振幅を y l と し、 y l Z y Oの値を減幅比と して定義する。 第 4図の場合、 減 幅比は 1 よ りも小さ く 、 炉心は安定な状態 （定常状態） に戻る。 このよ うな場合、 炉心は安定であるという。 一方、 第 5図の場合は、 減幅比は 1 よ りも大きく 、 炉心内の炉心流量の変動は時間の経過に伴って大きく なり、 炉心は不安定となる。 これは、 原子炉の運転上、 好ま しく ない状 態である。 従って、 炉心安定性の減幅比が 1 よ り小さい場合は安定、 そ れが 1 よ り大きい場合は不安定であると評価できる。 よって、 1未満で あれば安定と評価できるが、 実際には、 若干の余裕をとつて減幅比が Here, the amplitude of the disturbance applied to the core is defined as y0, the amplitude one cycle after that is defined as yl, and the value of ylZyO is defined as the attenuation ratio. In the case of Fig. 4, the attenuation ratio is smaller than 1, and the core returns to a stable state (steady state). In such a case, the core is said to be stable. On the other hand, in the case of FIG. 5, the width reduction ratio is larger than 1, the fluctuation of the core flow rate in the core increases with time, and the core becomes unstable. This is undesirable for the operation of the reactor. Therefore, it can be evaluated as stable if the reduction ratio of the core stability is smaller than 1, and unstable if it is larger than 1. Therefore, it can be evaluated as stable if it is less than 1, but in practice, the reduction ratio is
0. 8以下となるよう に設計している。 It is designed to be 0.8 or less.
本発明者らは、 1 0行 1 0列の燃料集合体において、 短尺燃料棒の本 数、 短尺燃料棒の燃料有効長をパラメータと して、 減幅比が 0. 8 とな る水ロ ッ ドの横断面積を求め、 短尺燃料棒の本数、 その燃料有効長と、 水ロ ッ ドの横断面積との関係を明らかにした。 なお、 9行 9列の従来燃 料集合体の平均取リ出し燃焼度 4 5 GW d / t よ り さ らに高燃焼度とな るよう に、 平均取リ出し燃焼度は 6 0 GW d Z t と した。 第 6図に解析 結果を示す。 第 6図の縦軸及び横軸は第 3図の各々と同じである。 圧力 損失における解析結果と同様に、 短尺燃料棒の本数毎に境界線がそれぞ れ発生する。 境界線 M l は短尺燃料棒が 1 2本、 境界線 M 2は短尺燃料 棒が 1 6本、 及び境界線 M 3は短尺燃料棒が 2 0本の、 それぞれの場合 における結果である。 短尺燃料棒の本数 1 6本の場合には、 境界線 M 2 が減幅比 0 . 8 となる条件を満足する境界であり、 境界線 M 2、 及び境 界線 M 2 よ りも上側の領域が減幅比 0 . 8 以下となる領域である。 従つ て、 全水口ッ ドの総横断面積が実線 M 2 を含む上側の領域となるように 構成すれば、 平均取り出し燃焼度 6 0 G W d Z t を達成でき、 かつ許容 される炉心安定性を維持できる。 すなわち、 A w r Z A c hは、 （数 5 ) を満足すればよい。 第 6図において、 燃料集合体内の短尺燃料棒 2 Bの 本数によって異なる各境界線は、 短尺燃料棒の本数 nをパラメータと し て含む （数 5 ) で現される。 The inventors of the present invention have proposed a fuel assembly of 10 rows and 10 columns, in which the number of short fuel rods and the active fuel length of the short fuel rods are used as parameters to obtain a water channel with a reduction ratio of 0.8. The cross-sectional area of the rod was determined, and the relationship between the number of short fuel rods, the effective fuel length, and the cross-sectional area of the water rod was clarified. The average take-out burnup is 60 GW d so that the burn-up is even higher than the average take-up burnup of 45 GW d / t of the 9-row, 9-column conventional fuel assembly. Z t. Figure 6 shows the analysis results. The vertical and horizontal axes in FIG. 6 are the same as those in FIG. Similar to the analysis results for pressure loss, a boundary line is generated for each short fuel rod. Boundary line M l has 12 short fuel rods, boundary line M 2 has 16 short fuel rods, and boundary line M 3 has 20 short fuel rods. It is a result in. When the number of short fuel rods is 16, the boundary M2 is the boundary that satisfies the condition that the reduction ratio is 0.8, and the area above the boundary M2 and the boundary M2 is satisfied. Is the area where the reduction ratio is 0.8 or less. Therefore, if the total cross-sectional area of all water outlets is configured to be the upper region including the solid line M2, an average take-out burnup of 60 GW d Zt can be achieved, and allowable core stability can be achieved. Can be maintained. That is, A wr ZA ch only needs to satisfy (Equation 5). In FIG. 6, each boundary line that depends on the number of short fuel rods 2B in the fuel assembly is expressed by (Equation 5) that includes the number n of short fuel rods as a parameter.
第 3図に示す圧力損失に対する各境界線、 第 6図に示す炉心安定性に 対する各境界線、 更に境界線 J及び Kを、 第 7図に示す。 短尺燃料棒が 1 2本の場合は、 炉心安定性から決まる最低限必要となる全水ロッ ドの 総横断面積を示す境界線 M 1 が、 点線 Kよ りも上側に位置する。 このた め、 短尺燃料棒が 1 2本の場合には、 本実施例での燃料棒 8本が占有す る領域において最大となる全水口 ッ ドの総横断面積以上の、 全水口ッ ド の総横断面積が、 必要となる。 従って、 短尺燃料棒が 1 2本では、 平均 取り出し燃焼度 6 0 G W d / t の条件で、 炉心安定性を満足することが できない。  Fig. 7 shows the boundaries for pressure loss shown in Fig. 3, the boundaries for core stability shown in Fig. 6, and the boundaries J and K. When there are 12 short fuel rods, the boundary line M 1 indicating the minimum cross-sectional area of all water rods, which is determined by the core stability, is located above the dotted line K. For this reason, when the number of the short fuel rods is 12, the total cross-sectional area of the total cross-sectional area of all the water ports, which is the largest in the area occupied by the eight fuel rods in this embodiment, is equal to or larger than Total cross-sectional area is required. Therefore, with 12 short fuel rods, core stability cannot be satisfied under the condition of an average removal burnup of 60 GW d / t.
以上のよう に、 燃料棒 8本が占有する領域に水ロッ ドを配置し、 燃料 棒配列の最外層以外に短尺燃料棒を配置した場合には、 圧力損失及び炉 心安定性の観点から、 1 5本以上の短尺燃料棒が必要となる。 ところで、 短尺燃料棒の本数を 2 1本よ りも増大すると、 ボイ ド係数は改善される が、 ウランインペン トリの減少し過ぎ、 及び燃料棒の間隔を所定幅に保 持する、 短尺燃料棒の上端よ リも上方に位置する燃料スぺーザの強度の 観点から望ま しく ない。 このため、 短尺燃料棒の本数は 2 0本以下にす る必要がある。 このため、 短尺燃料棒の本数 nは、 1 5≤ n≤ 2 0 を満 足する必要がある （数 2 ) 。 As described above, when water rods are placed in the area occupied by eight fuel rods and short fuel rods are placed outside the outermost layer of the fuel rod arrangement, from the viewpoint of pressure loss and core stability, 1 5 or more short fuel rods are required. By the way, if the number of short fuel rods is increased beyond 21, the void coefficient will be improved, but the uranium inventory will decrease too much and the short fuel rods will keep the distance between the fuel rods at a predetermined width. It is not desirable from the viewpoint of the strength of the fuel spacer located above the upper end of the rod. For this reason, the number of short fuel rods should be less than 20. Need to be Therefore, the number n of short fuel rods must satisfy 15 ≤ n ≤ 20 (Equation 2).
第 7図において、 ハッチングを施した領域が、 1 6本の短尺燃料棒を 配置した本実施例の 1 0行 1 0列の燃料集合体に対して、 （数 1 ) ， (数 3 ) から （数 6 ) を満足する領域である。 この領域になるように、 L p / L f 及び水口 ッ ド 3の横断面積が設定される。 しかしながら、 1 5 ≤ n≤ 2 0の場合においても、 （数 1 )， （数 3 ) から （数 6 ) を満 足させる領域がそれぞれ存在する。  In FIG. 7, the hatched area indicates the relationship between (Equation 1) and (Equation 3) for the fuel assembly of 10 rows and 10 columns of the present embodiment in which 16 short fuel rods are arranged. This is an area that satisfies (Equation 6). Lp / Lf and the cross-sectional area of the water outlet 3 are set to be in this area. However, even in the case of 15 ≤ n ≤ 20, there are regions that satisfy (Equation 1) and (Equation 3) through (Equation 6).
本実施例によれば、 平均取り出し燃焼度 6 O GW d Z t以上を達成で き、 従来の燃料集合体よ りも圧力損失を増加させることなく 、 許容され る炉心安定性を得ることができる。 更に、 本実施例の燃料集合体は、 既 設の沸騰水型原子炉に適用することができる。 特開平 5— 232273 号公報 は、 1 0行 1 0列の燃料棒配列を有する燃料集合体で燃焼度 6 0 G W d Z t以上を達成するこ とについて何も言及していない。 本実施例の燃料 集合体は、 （数 1 ) から （数 6 ) の条件を満足するこ とによ って、 燃焼 度 6 O GW d Z t以上を達成する、 1 0行 1 0列の燃料棒配列を有する 燃料集合体において、 従来の燃料集合体よ りも圧力損失を増加させるこ となく 、 許容される炉心安定性を得ることができるよう になったのであ る。  According to the present embodiment, an average take-out burnup of 6 OGW d Zt or more can be achieved, and acceptable core stability can be obtained without increasing pressure loss as compared with a conventional fuel assembly. . Further, the fuel assembly of the present embodiment can be applied to an existing boiling water reactor. JP-A-5-232273 does not mention anything about achieving a burnup of 60 GW dZt or more in a fuel assembly having a fuel rod array of 10 rows and 10 columns. The fuel assembly of this embodiment achieves a burnup of at least 6 OGW d Zt by satisfying the conditions of (Equation 1) to (Equation 6). In a fuel assembly having a fuel rod array, acceptable core stability can be obtained without increasing pressure loss as compared with a conventional fuel assembly.
本実施例においては、 短尺燃料棒を、 最外層に配置しなければ、 第 1 図と異なる位置に配置しても、 同じ効果が得られる。 また、 水ロッ ドも、 総横断面積が同一であれば、 第 8図に示すよう に矩形の水口 ッ ド 3 Aと しても、 またこれら以外の形状と しても同じ効果を生じる。 なお、 本実 施例は （数 2 0 ) にチャ ンネルボックス内幅 D c b、 燃料棒の外径 D f が含まれているので、 燃料棒の外径， チャンネルボックス内幅の若干の 変化にも適用できる。 In this embodiment, if the short fuel rods are not arranged in the outermost layer, the same effects can be obtained even if they are arranged at positions different from those in FIG. In addition, if the water rod has the same total cross-sectional area, the same effect can be obtained by using a rectangular water port 3A as shown in Fig. 8 or other shapes. In this embodiment, since (Equation 20) includes the inner diameter D cb of the channel box and the outer diameter D f of the fuel rod, the outer diameter of the fuel rod and the inner width of the channel box are slightly smaller. It can be applied to change.
(実施例 2 )  (Example 2)
以下、 本発明の第 2実施例である燃料集合体を、 第 9 図を用いて説明 する。 本実施例の燃料集合体 1 Cは、 沸騰水型原子炉の炉心に装荷され る。 燃料集合体 1 Cは、 第 1 図に示す燃料集合体 1 の 2本の水ロ ッ ド 3 を、 1 本の水ロ ッ ド 3 C に替えたものである。 本実施例の他の構成は、 第 1 図に示す燃料集合体と同じである。 水ロ ッ ド 3 Cは.、 横断面が円形 を してお り 、 9 本の燃料棒が配置可能な領域を占有している。 水ロ ッ ド 3 Cの軸心は、 燃料集合体の軸心よ り も、 沸騰水型原子炉の炉心内に装 荷された状態で燃料集合体 1 Cの制御棒に面するコーナー部 8 の反対側 にずれている。 このため、 コーナー部 8側では、 水ロ ッ ド 3 Cチャ ンネ ルボックス 7 との間に 4層の燃料棒配列が存在する。 ま た、 コーナー部 8 の反対側では、 水口 ッ ド 3 Cチャ ンネルボックス 7 との間に 3層の燃 料棒配列が存在する。 1 2本の短尺燃料棒 2 Bが、 外側から 2層目の燃 料棒配列において各コーナ一及び各コーナーから 1 本間を置いた位置に 配置される。 チャ ンネルボックス 7 の内幅 D e b ， 燃料棒 2 の外径 D f ， 燃料棒ピツチ P f 、 及び燃料棒 2 Aの燃料有効長 L f の寸法は、 燃料集 合体 1 のそれぞれと同じである。 本実施例も、 短尺燃料棒 2 B を燃料棒 配列の最外層に配置していない。  Hereinafter, a fuel assembly according to a second embodiment of the present invention will be described with reference to FIG. The fuel assembly 1C of this embodiment is loaded on the core of a boiling water reactor. The fuel assembly 1C is obtained by replacing the two water rods 3 of the fuel assembly 1 shown in FIG. 1 with one water rod 3C. Other configurations of the present embodiment are the same as those of the fuel assembly shown in FIG. The water rod 3C has a circular cross section and occupies an area where nine fuel rods can be placed. The axis of the water rod 3 C is located at the corner 8 facing the control rod of the fuel assembly 1 C when loaded in the core of the boiling water reactor 8 rather than the axis of the fuel assembly 8. It is shifted to the opposite side of. Therefore, on the corner 8 side, there is a four-layer fuel rod arrangement between the water rod 3C and the channel box 7. Also, on the opposite side of the corner 8, there are three layers of fuel rod arrangement between the water inlet 3 C and the channel box 7. 1 Two short fuel rods 2B are arranged at a position between each corner and one from each corner in the fuel rod array of the second layer from the outside. The dimensions of the inner width D eb of the channel box 7, the outer diameter D f of the fuel rod 2, the fuel rod pitch P f, and the active fuel length L f of the fuel rod 2 A are the same as those of the fuel assembly 1. . Also in this embodiment, the short fuel rods 2B are not arranged on the outermost layer of the fuel rod array.
燃料集合体 1 Cは、 短尺燃料棒 2 Bの燃料有効長 L p ， 水ロ ッ ド 3 C の総横断面積 A w r を、 （数 1 ) , (数 4 )， （数 7 ) から （数 1 0 ) の条 件を満たすよ う構成したものである。 （数 7 ) から （数 1 0 ) の条件は、 発明者らの検討によ って見出されたものである。  The fuel assembly 1C calculates the effective fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3C from (Equation 1), (Equation 4), (Equation 7) to (Equation 7). 10)). The conditions of (Equation 7) to (Equation 10) have been found through studies by the inventors.
実施例 1 と同様に、 本実施例の燃料集合体 1 C における圧力損失及び 炉心安定性それぞれの解析から導出 した境界線の一例を、 第 1 0 図に示 す。 第 1 0図に示す境界線 L 4は、 燃料棒配列の最外層以外で燃料集合 体 1 C内に 1 2本の短尺燃料棒 2 Bを配置したときの圧力損失に対する 境界線である。 境界線 M 4は、 同様に、 1 2本の短尺燃料棒 2 Bを配置 したときの炉心安定性に対する境界線である。 As in Example 1, an example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1C of this example is shown in Fig. 10. You. A boundary line L4 shown in FIG. 10 is a boundary line for the pressure loss when 12 short fuel rods 2B are arranged in the fuel assembly 1C other than the outermost layer of the fuel rod array. Similarly, boundary line M4 is a boundary line for core stability when 12 short fuel rods 2B are arranged.
ところで、 燃料集合体 1 Cにおける冷却材流路面積 A c hは、 概略、 次式で表される。  By the way, the coolant flow passage area A ch in the fuel assembly 1 C is roughly expressed by the following equation.
A c h = D c b 2 - ?c / 4 X D f 2 x ( l 0 0 - 9 ) - Aw r A ch = D cb 2- ? C / 4 XD f 2 x (l 0 0-9)-Aw r
… （数 2 4 ) … (Number 2 4)
(数 2 4 ) に本実施例での前述の該当する数値を代入すると、 By substituting the above numerical values in this embodiment into (Equation 24),
A c h = 1 0 4 3 2 - Aw r (mm2 ) … （数 2 5 ) となる。 A ch = 1 0 4 3 2-Awr (mm 2 ) ... (Equation 25)
また、 第 1 0図内の点線 K 1 は 9本の燃料棒が配置可能な領域を占有 する水口ッ ドの総横断面積 Aw r の最大値を示しており、 次式で表され る。  The dotted line K1 in Fig. 10 indicates the maximum value of the total cross-sectional area Awr of the water inlet occupying the area where nine fuel rods can be arranged, and is expressed by the following equation.
Aw Ρ " Χ 9 … （数 2 6 ) よって、 水口ッ ド総横断面積の上限値に対する Aw r ZA c hの値は、 Aw r /A c h = l 5 0 9 /( 1 0 4 3 2 - 1 5 0 9 ) = 0. 1 6 9 Aw Ρ "Χ 9… (Equation 26) Therefore, the value of Aw r ZA ch with respect to the upper limit value of the total cross-sectional area of the water mouth pad is Awr / A ch = l509 / (1 0 4 3 2-1 5 0 9) = 0.1 6 9
… （数 2 7 ) となる。 従って、 Aw r ZA c hは、 0. 1 6 9 以下にしなければなら ない （数 8 ) 。 … (Equation 2 7). Therefore, Aw r ZA ch must be less than 0.169 (Equation 8).
また、 本実施例において、 必要とする短尺燃料棒 2 Bの本数は、 実施 例 1 と同様な検討によって、 1 0〜 2 0の範囲となった。  In the present embodiment, the number of short fuel rods 2B required was in the range of 10 to 20 by the same study as in the first embodiment.
第 1 0図において、 （数 8 ) は点線 K 1 を含みかつ点線 K 1 よ り も下 方の領域に該当し、 （数 4 ) は点線 J を含みかつ点線 J よ りも右側の領 域に該当する。 第 1 0図においてハッチングを施した領域は、 1 2本の 短尺燃料棒 2 Bが第 9図のように配置された場合において （数 1 )， （数 4 ) 及び （数 8 ) から （数 1 0 ) を満足する領域である。 この領域にな るよう に、 L p Z L f 及び水ロッ ド 3の横断面積が設定される。 しかし ながら、 （数 7 ) を満足する場合、 すなわち 1 0≤ n≤ 2 0の場合にお いても、 （数 1 ) , (数 4 ) 及び （数 8 ) から （数 1 0 ) を満足させる領 域がそれぞれ存在する。 In FIG. 10, (Equation 8) corresponds to an area including the dotted line K1 and below the dotted line K1, and (Equation 4) includes an area including the dotted line J and to the right of the dotted line J. Corresponds to. The hatched area in FIG. In the case where the short fuel rods 2B are arranged as shown in FIG. 9, this is an area that satisfies (Equation 10) from (Equation 1), (Equation 4) and (Equation 8). LpZLf and the cross-sectional area of water rod 3 are set to be in this area. However, when (Equation 7) is satisfied, that is, when 10≤n≤20, (Equation 1), (Equation 4) and (Equation 8) satisfy (Equation 10). Each region exists.
本実施例によれば、 第 1実施例と同様の効果が得られる。 また、 短尺 燃料棒は最外層に配置しなければ、 第 9図と異なる配置と しても、 更に、 第 1 1 図に示す燃料集合体 1 Dと してもよい。 燃料集合体 1 Dは、 燃料 集合体 1 Cにおいて水口ッ ド 3 Cを矩形の横断面を有する水口ッ ド 3 D に替えたものである。  According to this embodiment, the same effects as in the first embodiment can be obtained. If the short fuel rods are not arranged in the outermost layer, they may be arranged differently from those in FIG. 9 or may be the fuel assembly 1D shown in FIG. The fuel assembly 1D is obtained by replacing the water port head 3C in the fuel assembly 1C with a water port head 3D having a rectangular cross section.
(実施例 3 )  (Example 3)
以下、 本発明第 3実施例である燃料集合体を、 第 1 2図を用いて説明 する。 本実施例の燃料集合体 1 Eは、 沸騰水型原子炉の炉心に装荷され る。 燃料集合体 1 Eは、 燃料集合体 1 (第 1 図） の 2本の水ロッ ド 3 を、 3本の水ロッ ド 3 Eに替えたものである。 3本の水ロ ッ ド 3 Eは、 燃料 集合体 1 Eの制御棒に面するコーナー部 8 に対する対角線と直交する他 の対角線上に位置しており、 互いに隣接している。 真中の 1 本の水口 ッ ド 3 Eは、 コーナ一部 8 に対する対角線上にも配置される。 すなわち、 この 1 本の水口 ッ ド 3 Eは燃料集合体 1 Eの軸線上に位置する。 3本の 水ロッ ド 3 Eは、 1 0本の燃料棒 2が配置可能な領域を占有している。 水ロッ ド 3 Eの外径は水ロ ッ ド 3 (第 1 図） の外径よ りも小さい。 短尺 燃料棒 2 Bは 1 0本配置される。 そのうちの 8本の短尺燃料棒 2 Bは、 外側から 2層目の燃料棒配列内に配置される。 残りの 2本の短尺燃料棒 2 Bは、 外側から 4層目の燃料棒配列の各コーナーに配置される。 2層 目の燃料棒配列では、 各コーナーに短尺燃料棒 2 Bが配置される。 本実 施例のチャ ンネルボックス 7の内幅 D c b ， 燃料棒 2の外径 D f ， 燃料 棒ピッチ P i 、 及び燃料棒 2 Aの燃料有効長 L f の寸法は、 燃料集合体 1 のそれぞれと同じである。 本実施例は、 燃料棒配列の最外層には、 短 尺燃料棒 2 Bを配置していない。 Hereinafter, a fuel assembly according to a third embodiment of the present invention will be described with reference to FIG. The fuel assembly 1E of this embodiment is loaded on the core of a boiling water reactor. Fuel assembly 1E replaces the two water rods 3 in fuel assembly 1 (Fig. 1) with three water rods 3E. The three water rods 3E are located on another diagonal orthogonal to the diagonal to the corner 8 facing the control rod of the fuel assembly 1E, and are adjacent to each other. The middle water outlet pad 3E is also arranged diagonally to the corner part 8. That is, the one water port 3E is located on the axis of the fuel assembly 1E. The three water rods 3E occupy an area where ten fuel rods 2 can be placed. The outer diameter of water rod 3E is smaller than the outer diameter of water rod 3 (Fig. 1). 10 short fuel rods 2B are arranged. Eight of the short fuel rods 2B are arranged in the fuel rod array of the second layer from the outside. The remaining two short fuel rods 2B are arranged at each corner of the fuel rod array in the fourth layer from the outside. 2 layers In the eye fuel rod arrangement, short fuel rods 2B are arranged at each corner. The dimensions of the inner width D cb of the channel box 7, the outer diameter D f of the fuel rod 2, the fuel rod pitch P i, and the active fuel length L f of the fuel rod 2 A of the fuel assembly 1 in the present embodiment are as follows. Same as each. In this embodiment, the short fuel rods 2B are not arranged in the outermost layer of the fuel rod array.
燃料集合体 1 Eは、 短尺燃料棒 2 Bの燃料有効長 L p、 水ロ ッ ド 3 E の総横断面積 Aw r を、 （数 1 )， （数 4)， （数 1 1 ) から （数 1 4 ) の 条件を満たすよう構成したものである。 （数 1 1 ) から （数 1 4 ) の条 件は、 発明者らの検討によって見出されたものである。  The fuel assembly 1E calculates the active fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3E from (Equation 1), (Equation 4), and (Equation 11) as ( It is configured to satisfy the condition of Equation 14). The conditions from (Equation 11) to (Equation 14) were found by the inventors' studies.
実施例 1 と同様に、 本実施例の燃料集合体 1 Eにおける圧力損失及び 炉心安定性それぞれの解析から導出した境界線の一例を、 第 1 3図に示 す。 第 1 3図に示す境界線 L 5は、 燃料棒配列の最外層以外で燃料集合 体 1 E内に 1 0本の短尺燃料棒 2 Bを配置したときの圧力損失に対する 境界線である。 境界線 M 5は、 同様に 1 0本の短尺燃料棒 2 Bを配置し たときの炉心安定性に対する境界線である。  As in the first embodiment, an example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1E of the present embodiment is shown in Fig. 13. A boundary line L5 shown in FIG. 13 is a boundary line for the pressure loss when 10 short fuel rods 2B are arranged in the fuel assembly 1E except for the outermost layer of the fuel rod array. A boundary line M5 is a boundary line for core stability when ten short fuel rods 2B are similarly arranged.
ところで、 燃料集合体 1 Eにおける冷却材流路面積 A c hは、 概略、 次式で表される。  By the way, the coolant flow passage area A ch in the fuel assembly 1E is roughly expressed by the following equation.
A c h = D c b 2 - 7c / 4 x D f 2 x ( l 0 0 - 1 0 ) - A w r A ch = D cb 2 - 7c / 4 x D f 2 x (l 0 0 - 1 0) - A wr
… （数 2 8 ) … (Number 2 8)
(数 2 7 ) に本実施例での前述の該当する数値を代入すると、 By substituting the above-mentioned corresponding numerical values in the present embodiment into (Equation 27),
A c h = 1 0 5 1 5 - Aw r (mm2 ) … （数 2 9 ) となる。 A ch = 10 5 15-A w r (mm 2 ) ... (Equation 29).
また、 第 1 3図の点線 K 2は 1 0本の燃料棒が配置可能な領域を占有 する水口ッ ドの総横断面積 Aw r の最大値を示しており、 次式で表され る。 A w r = P f 2 X 1 0 … （数 3 0 ) よって、 水口ッ ド総横新面積の上限値に対する Aw r ZA c hの値は、 Aw r /A c h = l 6 7 7 /( 1 0 5 1 5— 1 6 7 7 ) = 0. 1 9 0 The dotted line K2 in Fig. 13 indicates the maximum value of the total cross-sectional area Awr of the water mouth occupying the area where 10 fuel rods can be arranged, and is expressed by the following equation. A wr = P f 2 X 1 0… (Equation 30) Therefore, the value of Aw r ZA ch with respect to the upper limit value of the total new horizontal area of the water mouth pad is A wr / A ch = l 6 7 7 / (1 0 5 1 5—1 6 7 7) = 0.19
… （数 3 1 ) となる。 従って、 Aw r ZA c hは、 0. 1 9 0 以下にしなければなら ない （数 1 2 ) 。  … (Equation 3 1). Therefore, Aw r ZA ch must be less than 0.190 (Equation 1 2).
また、 本実施例において、 必要とする短尺燃料棒 2 Bの本数は、 実施 例 1 と同様な検討によって、 9 ~ 2 0の範囲となった。  In the present embodiment, the number of short fuel rods 2B required was in the range of 9 to 20 by the same study as in the first embodiment.
第 1 3図において、 （数 1 2 ) は点線 K 1 を含みかつ点線 K 2よ りも 下方の領域に該当し、 （数 4 ) は点線 J を含みかつ点線 J よ りも右側の 領域に該当する。 第 1 3図においてハッチングを施した領域は、 1 0本 の短尺燃料棒 2 Bが第 1 2図のように配置された場合において （数 1 )， (数 4 ) 及び （数 1 2 ) から （数 1 4 ) を満足する領域である。 この領 域になるよう に、 L p Z L f 及び水口 ッ ド 3の横断面積が設定される。 しかしながら、 （数 1 1 ) を満足する場合、 すなわち 1 0≤ n≤ 2 0の 場合においても、 （数 1 )， （数 4 ) 及び （数 1 2 ) から （数 1 4 ) を満 足させる領域がそれぞれ存在する。  In Fig. 13, (Equation 12) corresponds to the area including the dotted line K1 and below the dotted line K2, and (Equation 4) corresponds to the area including the dotted line J and to the right of the dotted line J. Applicable. In FIG. 13, the hatched area is based on (Equation 1), (Equation 4) and (Equation 12) when the ten short fuel rods 2B are arranged as shown in FIG. This is an area that satisfies (Equation 14). LpZLf and the cross-sectional area of the water mouth pad 3 are set so as to be in this area. However, even when (Equation 11) is satisfied, that is, when 10≤n≤20, (Equation 14) is satisfied from (Equation 1), (Equation 4) and (Equation 12). Each area exists.
本実施例によれば、 第 1実施例と同様の効果が得られる。 また、 短尺 燃料棒は最外層に配置しなければ、 第 1 2図と異なる配置と しても、 更 に、 第 1 4図に示す燃料集合体 1 Fと してもよい。 燃料集合体 1 Fは、 燃料集合体 1 Eにおいて 3本の水口 ッ ド 3 Eを 1本に併せた水口 ッ ド 3 Fに替えたものである。 水ロッ ド 3 Fは、 3本の水ロッ ド 3 Cと同じ 位置に配置される。  According to this embodiment, the same effects as in the first embodiment can be obtained. If the short fuel rods are not arranged in the outermost layer, they may be arranged differently from those in FIG. 12 or may be a fuel assembly 1F shown in FIG. The fuel assembly 1F is obtained by replacing the three water inlets 3E in the fuel assembly 1E with a single water inlet 3F. Water rod 3F is located at the same position as three water rods 3C.
(実施例 4 )  (Example 4)
以下、 本発明の第 4実施例である燃料集合体 1 Gを、 第 1 5図を用い て説明する。 燃料集合体 1 Gは、 沸騰水型原子炉の炉心に装荷される。 燃料集合体 1 Gは、 第 1 図に示す燃料集合体 1 において短尺燃料棒 2 B の配置を替えた構成を有する。 すなわち、 短尺燃料棒 2 Bは、 外側から 2層目の燃料棒配列内に配置されていなく 、 最外層の燃料棒配列内に配 置されている。 最外層においては、 各辺の中央部に 2本の短尺燃料棒 2 Bが互いに隣接して配置される。 燃料集合体 1 Gの他の構成は、 燃料 集合体 1 と同じである。 チャ ンネルボックス 7の内幅 D c b ， 燃料棒 2 の外径 D f ， 燃料棒ピッチ P f 、 及び燃料棒 2 Aの燃料有効長 L f の寸 法は、 燃料集合体 1 のそれぞれと同じである。 Hereinafter, a fuel assembly 1G according to a fourth embodiment of the present invention will be described with reference to FIG. Will be explained. The 1 G fuel assemblies are loaded into the core of a boiling water reactor. The fuel assembly 1G has a configuration in which the arrangement of the short fuel rods 2B is changed in the fuel assembly 1 shown in FIG. That is, the short fuel rods 2B are not arranged in the fuel rod array of the second layer from the outside, but are arranged in the outermost fuel rod array. In the outermost layer, two short fuel rods 2B are arranged adjacent to each other at the center of each side. Other configurations of the fuel assembly 1G are the same as those of the fuel assembly 1. The dimensions of the inner width D cb of the channel box 7, the outer diameter D f of the fuel rod 2, the fuel rod pitch P f, and the active fuel length L f of the fuel rod 2 A are the same as those of the fuel assembly 1. is there.
燃料集合体 1 Gは、 短尺燃料棒 2 Bの燃料有効長 L p ， 水ロ ッ ド 3の 総横断面積 Aw r を、 （数 1 )， （数 3 ) , (数 4)， （数 6 )， （数 1 1 ) 及 び （数 1 5 ) の条件を満たすよう構成したものである。 これらの数式で 示される条件は、 発明者らの検討によって見出されたものである。  The fuel assembly 1G calculates the active fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3 by (Equation 1), (Equation 3), (Equation 4), and (Equation 6). ), (Equation 11) and (Equation 15). The conditions represented by these formulas have been found by the study of the inventors.
実施例 1 と同様に、 本実施例の燃料集合体 1 Gにおける圧力損失及び 炉心安定性それぞれの解析から導出した境界線の一例を第 1 6図に示す。 第 1 6図に示す境界線 L 6は、 最外層の燃料棒配列内を含んで燃料集合 体 1 G内に 1 2本の短尺燃料棒 2 Bを配置したときの圧力損失に対する 境界線である。 境界線 M 6は、 同様に、 1 2本の短尺燃料棒 2 Bを配置 したときの炉心安定性に対する境界線である。 本実施例では、 ポイ ド係 数の改善効果が大きい位置、 すなわち燃料棒配列の最外層及び水口ッ ド に隣接した位置に短尺燃料棒 2 Bを全て配置しているので、 炉心安定性 に対する条件 （数 1 5 ) が実施例 1 における炉心安定性に対する条件 (数 5 ) と異なっている。 同じ炉心安定性であれば、 本実施例における 水ロッ ド 3の総横断面積は、 実施例 1 のそれよ りも小さ く なる。 一方、 本実施例において圧力損失から決定される条件 （数 6 ) は、 短尺燃料棒 の配置には影響されず、 実施例 1 と同じである。 また、 Aw rノ A c h の上限値は、 実施例 1 と同様に （数 2 3 ) で示される値である。 本実施 例において、 必要とする短尺燃料棒 2 Bの本数は、 実施例 1 と同様な検 討によって、 9〜 2 0の範囲となった。 As in the case of Example 1, an example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1 G of the present example is shown in FIG. 16. The boundary line L 6 shown in FIG. 16 is the boundary line for the pressure loss when 12 short fuel rods 2 B are arranged in the fuel assembly 1 G including the inside of the outermost fuel rod array. . Similarly, boundary line M 6 is a boundary line for core stability when 12 short fuel rods 2 B are arranged. In this embodiment, since all the short fuel rods 2B are arranged at the position where the effect of improving the coefficient of pond is large, that is, at the position adjacent to the outermost layer of the fuel rod arrangement and the water port, conditions for the core stability are required. (Equation 15) is different from the condition (Equation 5) for core stability in Example 1. With the same core stability, the total cross-sectional area of the water rod 3 in this embodiment is smaller than that of the first embodiment. On the other hand, the condition (Equation 6) determined from the pressure loss in this embodiment is as follows: The arrangement is the same as that of the first embodiment, without being affected by the arrangement of the first embodiment. The upper limit value of Awr Ach is the value indicated by (Equation 23) as in the first embodiment. In the present embodiment, the number of short fuel rods 2B required was in the range of 9 to 20 by the same study as in the first embodiment.
第 1 6図においてハッチングを施した領域は、 1 2本の短尺燃料棒 2 Bが第 1 5図のよう に配置された場合において （数 1 )， （数 3 )， （数 4)， （数 6 ) 及び （数 1 5 ) を満足する領域である。 この領域になるよ う に、 L p / L f 及び水ロッ ド 3の横断面積が設定される。 しかしなが ら、 （数 1 1 ) を満足する場合、 すなわち 1 0 ≤ n≤ 2 0の場合におい ても、 （数 1 )， （数 3 )， （数 4)， （数 6 ) 及び （数 1 5 ) を満足させる 領域がそれぞれ存在する。  In FIG. 16, the hatched areas are (Equation 1), (Equation 3), (Equation 4), and (Equation 1) when the two short fuel rods 2B are arranged as shown in FIG. This is an area that satisfies Equations 6) and 15). Lp / Lf and the cross-sectional area of water rod 3 are set to be in this area. However, even when (Equation 1 1) is satisfied, that is, when 10 ≤ n ≤ 20, (Equation 1), (Equation 3), (Equation 4), (Equation 6) and (Equation 6) There are regions that satisfy Equation 15).
短尺燃料棒 2 Bを最外層に配置することによって、 外側から 2層目の 燃料棒配列に短尺燃料棒 2 Bを配置した場合に比べて倍以上にボイ ド係 数が低下する。 短尺燃料棒 2 Bが最外層のコーナーに配置したとき、 ポ イ ド係数の低下率は最も大きく なる。 しかしながら、 短尺燃料棒 2 Bを 最外層のコーナーに配置した場合には、 反応度損失、 及びそのコーナー に配置した短尺燃料棒 2 Bの局所出力ピーキングが共に大きく なる。 こ のため、 短尺燃料棒 2 Bをそのコーナーに配置することは避けなければ ならない。 最外層においてコーナ一以外の位置に短尺燃料棒 2 Bを配置 することによって反応度損失を低減できる。 更に、 本実施例のよう に、 各水口 ッ ド 3が配置されている行又は列の燃料棒配列と交差する、 最外 層の燃料棒配列内の位置 （具体的には最外層の各辺において中央部に配 置された 4本の燃料棒位置） に、 短尺燃料棒 2 Bを配置することによつ て、 反応度損失及び局所出力ピーキングを低減できる。  By arranging the short fuel rods 2B in the outermost layer, the void coefficient is reduced more than twice as compared with the case where the short fuel rods 2B are arranged in the fuel rod arrangement of the second layer from the outside. When the short fuel rods 2B are arranged at the corners of the outermost layer, the rate of decrease of the poid coefficient becomes the largest. However, when the short fuel rods 2B are arranged at the outermost corners, both the reactivity loss and the local power peaking of the short fuel rods 2B arranged at the corners increase. Therefore, it is necessary to avoid arranging the short fuel rod 2B at the corner. By arranging the short fuel rods 2B at positions other than the corners in the outermost layer, the reactivity loss can be reduced. Further, as in this embodiment, the position in the outermost fuel rod array (specifically, each side of the outermost layer) intersects with the fuel rod array in the row or column in which each water outlet pad 3 is arranged. By arranging the short fuel rods 2B at the four fuel rod positions arranged at the center in the example, reactivity loss and local output peaking can be reduced.
本実施例によれば、 第 1実施例と同様の効果が得られ、 更にポイ ド係 数を低減できる。 また、 反応度損失及び局所出力ピーキングも低減でき る。 According to the present embodiment, the same effects as those of the first embodiment can be obtained, and The number can be reduced. In addition, reactivity loss and local output peaking can be reduced.
短尺燃料棒は、 最外層内の位置及び水口ッ ドに隣接した位置の両方、 または最外層内の位置のみに配置すれば、 第 1 5図と異なる配置と して も、 更に、 第 1 7図に示す燃料集合体 1 Hと してもよい。 燃料集合体 1 Hは、 燃料集合体 1 Gにおいて水口 ッ ド 3 を横断面が矩形の水ロ ッ ド 3 Aに替えたものである。 2本の水ロ ッ ド 3 Aは、 2本の水ロ ッ ド 3 と同 じ位置に配置される。  If the short fuel rods are placed both in the outermost layer and in the position adjacent to the water outlet, or only in the outermost layer, they may be arranged differently from those in Fig. The fuel assembly 1H shown in the figure may be used. The fuel assembly 1H is obtained by replacing the water port 3 in the fuel assembly 1G with a water rod 3A having a rectangular cross section. The two water rods 3 A are arranged at the same position as the two water rods 3.
(実施例 5 )  (Example 5)
以下、 本発明の第 5実施例である燃料集合体 1 I を、 第 1 8図を用い て説明する。 燃料集合体 1 I は、 沸騰水型原子炉の炉心に装荷される。 燃料集合体 1 I は、 第 9図に示す燃料集合体 1 Cにおいて短尺燃料棒 2 Bの配置を替えた構成を有する。 燃料集合体 1 I の他の構成は、 燃料 集合体 1 Cと同じである。 燃料集合体 1 I の水ロッ ド 3 Cの配置も、 燃 料集合体 1 Cと同じである。 本実施例は、 1 2本の短尺燃料棒 2 Bを備 えている。 これらの短尺燃料棒 2 Bは、 外側から 2層目の燃料棒配列に 配置されていない。 8本の短尺燃料棒 2 Bは、 最外層の燃料棒配列内に 配置されており、 この燃料棒配列の各辺の中央部に 2本ずつ互いに隣接 して配置されている。 残りの 4本の短尺燃料棒 2 Bは、 燃料集合体 1 I が沸騰水型原子炉の炉心内に装荷された状態で制御棒に面する側のコー ナ一部 8側において、 外側から 4層目の燃料棒配列内に配置され、 コ一 ナ一部 8 とは反対側において、 外側から 3層目の燃料棒配列内に配置さ れる。 これらの 4本の短尺燃料棒 2 Bはいずれも水口ッ ド 3 Cに隣接し ている。 チャンネルボックス 7の内幅 D c b ， 燃料棒 2の外径 D f ， 燃 料棒ピッチ P f 、 及び燃料棒 2 Aの燃料有効長 L f の寸法は、 燃料集合 体 1 のそれぞれと同じである。 Hereinafter, a fuel assembly 1I according to a fifth embodiment of the present invention will be described with reference to FIG. Fuel assembly 1 I is loaded into the core of a boiling water reactor. The fuel assembly 1I has a configuration in which the arrangement of the short fuel rods 2B is changed in the fuel assembly 1C shown in FIG. Other configurations of the fuel assembly 1I are the same as those of the fuel assembly 1C. The arrangement of the water rod 3 C of the fuel assembly 1 I is the same as that of the fuel assembly 1 C. This embodiment is provided with 12 short fuel rods 2B. These short fuel rods 2B are not arranged in the fuel rod array of the second layer from the outside. The eight short fuel rods 2B are arranged in the outermost fuel rod array, and two fuel rods 2B are arranged adjacent to each other at the center of each side of the fuel rod array. The remaining four short fuel rods 2 B are located at the corner part 8 on the side facing the control rods with the fuel assembly 1 I loaded in the core of the boiling water reactor. The fuel rods are arranged in the fuel rod array of the third layer, and are arranged in the fuel rod array of the third layer from the outside on the side opposite to the corner part 8. These four short fuel rods 2B are all adjacent to the water inlet 3C. The dimensions of the inner width D cb of the channel box 7, the outer diameter D f of the fuel rod 2, the fuel rod pitch P f, and the active fuel length L f of the fuel rod 2 A are as follows. Same as each of body 1.
燃料集合体 1 I は、 短尺燃料棒 2 Bの燃料有効長 L p、 水ロッ ド 3の 総横断面積 A w r を、 （数 1 )， （数 4)， （数 8 )， （数 1 0 )， （数 1 6 ) 及び （数 1 7 ) の条件を満たすよう構成したものである。 これらの数式 で示される条件は、 発明者らの検討によって見出されたものである。 実施例 1 と同様に、 本実施例の燃料集合体 1 I における圧力損失及び 炉心安定性それぞれの解析から導出した境界線の一例を第 1 9図に示す。 第 1 9図に示す境界線 L 7は、 最外層の燃料棒配列内を含んで燃料集合 体 1 I 内に 1 2本の短尺燃料棒 2 Bを配置したときの圧力損失に対する 境界線である。 境界線 M 7は、 同様に、 1 2本の短尺燃料棒 2 Bを配置 したときの炉心安定性に対する境界線である。 本実施例では、 ポイ ド係 数の改善効果が大きい位置、 すなわち燃料棒配列の最外層内の位置、 及 び水口 ッ ドに隣接した位置に短尺燃料棒 2 Bを全て配置しているので、 炉心安定性に対する条件 （数 1 7 ) が実施例 2 における炉心安定性に対 する条件 （数 9 ) と異なっている。 同じ炉心安定性であれば、 本実施例 における水口 ッ ド 3 Cの総横断面積は、 実施例 2のそれよ りも小さ く な る。 一方、 本実施例において圧力損失から決定される条件 （数 1 0 ) は、 短尺燃料棒の配置には影響されず、 実施例 2 と同じである。 また、 Awr ZA c hの上限値は、 実施例 2 と同様に （数 2 7 ) で示される値である。 本実施例において、 必要とする短尺燃料棒 2 Bの本数は、 実施例 1 と同 様な検討によって、 8〜 2 0の範囲となった。  The fuel assembly 1 I calculates the active fuel length L p of the short fuel rod 2 B and the total cross-sectional area A wr of the water rod 3 by (Equation 1), (Equation 4), (Equation 8), (Equation 10). ), (Equation 16) and (Equation 17). The conditions represented by these formulas have been found by the inventors' studies. As in the first embodiment, an example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1I of the present embodiment is shown in FIG. The boundary line L7 shown in Fig. 19 is the boundary line for the pressure loss when 12 short fuel rods 2B are arranged in the fuel assembly 1I including the inside of the outermost fuel rod array. . Similarly, boundary line M7 is a boundary line for core stability when 12 short fuel rods 2B are arranged. In the present embodiment, all the short fuel rods 2B are arranged at positions where the effect of improving the coefficient of pond is large, that is, at positions in the outermost layer of the fuel rod array and at positions adjacent to the water inlet. The condition (Equation 17) for core stability is different from the condition (Equation 9) for core stability in Example 2. If the core stability is the same, the total cross-sectional area of the water inlet 3C in this embodiment is smaller than that of the second embodiment. On the other hand, the condition (Equation 10) determined from the pressure loss in the present embodiment is the same as that in Embodiment 2 without being affected by the arrangement of the short fuel rods. Also, the upper limit of Awr ZA ch is the value indicated by (Equation 27) as in the second embodiment. In the present embodiment, the number of short fuel rods 2B required was in the range of 8 to 20 by the same study as in the first embodiment.
第 1 9図においてハッチングを施した領域は、 1 2本の短尺燃料棒 2 Bが第 1 8図のよう に配置された場合において （数 1 )， （数 4)， （数 8 )， （数 1 0 ) 及び （数 1 7 ) を満足する領域である。 この領域になる ように、 L p Z L f 及び水ロッ ド 3 Cの横断面積が設定される。 しかし ながら、 （数 1 6 ) を満足する場合、 すなわち 8≤ n≤ 2 0の場合にお いても、 （数 1 )， （数 4)， （数 8 )， （数 1 0 ) 及び （数 1 7 ) を満足さ せる領域がそれぞれ存在する。 In FIG. 19, the hatched areas indicate (Equation 1), (Equation 4), (Equation 8), and (Equation 8) when the two short fuel rods 2B are arranged as shown in FIG. This is a region that satisfies (10) and (17). The cross-sectional area of LpZLf and the water rod 3C is set to be in this area. However However, when (Equation 16) is satisfied, that is, when 8≤n≤20, (Equation 1), (Equation 4), (Equation 8), (Equation 10), and (Equation 1) There are regions that satisfy (7).
本実施例によれば、 第 4実施例と同様の効果が得られる。 また、 短尺 燃料棒は、 最外層内の位置及び水ロッ ドに隣接した位置の両方、 または 最外層内の位置のみに配置すれば、 第 1 8図と異なる配置と しても、 更 に、 第 2 0図に示す燃料集合体 1 J と してもよい。 燃料集合体 1 J は、 燃料集合体 1 I において水口 ッ ド 3 Cを横断面が矩形の水口 ッ ド 3 Dに 替えたものである。 水ロ ッ ド 3 Dは、 水ロッ ド 3 Cと同じ位置に配置さ れる。  According to this embodiment, the same effects as in the fourth embodiment can be obtained. In addition, if the short fuel rods are placed both in the outermost layer and the position adjacent to the water rod, or only in the outermost layer, even if the arrangement is different from that in Fig. 18, The fuel assembly 1J shown in FIG. 20 may be used. Fuel assembly 1J is obtained by replacing water port 3C in fuel assembly 1I with water port 3D having a rectangular cross section. Water rod 3D is arranged at the same position as water rod 3C.
(実施例 6 )  (Example 6)
以下、 本発明の第 6実施例である燃料集合体 1 Kを、 第 2 1 図を用い て説明する。 燃料集合体 1 Kは、 沸騰水型原子炉の炉心に装荷される。 燃料集合体 1 Kは、 第 1 2図に示す燃料集合体 1 Eにおいて短尺燃料棒 2 Bの配置を替えた構成を有する。 燃料集合体 1 Kの他の構成は、 燃料 集合体 1 Eと同じである。 燃料集合体 1 Kの水ロッ ド 3 Eの配置も、 燃 料集合体 1 Eと同じである。 本実施例は、 1 0本の短尺燃料棒 2 Bを備 えている。 これらの短尺燃料棒 2 Bは、 外側から 2層目の燃料棒配列に 配置されていない。 8本の短尺燃料棒 2 Bは、 実施例 4と同様に最外層 の燃料棒配列内に配置されており、 この燃料棒配列の各辺の中央部に 2 本ずつ互いに隣接して配置されている。 残りの 2本の短尺燃料棒 2 Bは. 外側から 4層目の燃料棒配列内に配置され、 いずれも水口ッ ド 3 Eに隣 接している。 チャ ンネルボックス 7の内幅 D e b , 燃料棒 2の外径 D f : 燃料棒ピツチ P f 、 及び燃料棒 2 Aの燃料有効長 L f の寸法は、 燃料集 合体 1 のそれぞれと同じである。 燃料集合体 I Kは、 短尺燃料棒 2 Bの燃料有効長 L p、 水ロッ ド 3の 総横断面積 Aw r を、 （数 1 )， （数 4)， （数 1 2)， （数 1 4)， （数 1 8 ) 及び （数 1 9 ) の条件を満たすよう構成したものである。 これらの数式 で示される条件は、 発明者らの検討によって見出されたものである。 実施例 1 と同様に、 本実施例の燃料集合体 1 Kにおける圧力損失及び 炉心安定性それぞれの解析から導出した境界線の一例を第 2 2図に示す。 第 2 2図に示す境界線 L 8は、 最外層の燃料棒配列内を.含んで燃料集合 体 1 K内に 1 0本の短尺燃料棒 2 Bを配置したときの圧力損失に対する 境界線である。 境界線 M 8は、 同様に、 1 2本の短尺燃料棒 2 Bを配置 したときの炉心安定性に対する境界線である。 本実施例では、 ボイ ド係 数の改善効果が大きい位置、 すなわち燃料棒配列の最外層内の位置及び 水口ッ ドに隣接した位置に短尺燃料棒 2 Bを全て配置しているので、 炉 心安定性に対する条件 （数 1 9 ) が実施例 3 における炉心安定性に対す る条件 （数 1 3 ) と異なっている。 同じ炉心安定性であれば、 本実施例 における水口ッ ド 3 Cの総横断面積は、 実施例 2のそれよ りも小さ く な る。 一方、 本実施例において圧力損失から決定される条件 （数 1 4 ) は、 短尺燃料棒の配置には影響されず、 実施例 3 と同じである。 また、 Awr / A c hの上限値は、 実施例 3 と同様に （数 3 1 ) で示される値である。 本実施例において、 必要とする短尺燃料棒 2 Bの本数は、 実施例 1 と同 様な検討によって、 7〜 2 0の範囲となった。 Hereinafter, a fuel assembly 1K according to a sixth embodiment of the present invention will be described with reference to FIG. The 1 K fuel assemblies are loaded into the core of a boiling water reactor. The fuel assembly 1K has a configuration in which the arrangement of the short fuel rods 2B is changed in the fuel assembly 1E shown in FIG. Other configurations of the fuel assembly 1K are the same as those of the fuel assembly 1E. The layout of the water rod 3E of the fuel assembly 1K is the same as that of the fuel assembly 1E. This embodiment is provided with 10 short fuel rods 2B. These short fuel rods 2B are not arranged in the fuel rod array of the second layer from the outside. The eight short fuel rods 2B are arranged in the outermost fuel rod array similarly to the fourth embodiment, and two fuel rods 2B are arranged adjacent to each other at the center of each side of the fuel rod array. I have. The remaining two short fuel rods 2 B are arranged in the fourth-layer fuel rod array from the outside, and both are adjacent to the water port 3 E. Inner width D eb tea down channel box 7, the outer diameter of the fuel rods 2 D f: the dimensions of the fuel rod pitch P f, and the fuel rod 2 A fuel effective length L f is the same as defined in the fuel assembly 1 . The fuel assembly IK calculates the active fuel length Lp of the short fuel rod 2B and the total cross-sectional area Awr of the water rod 3 by (Equation 1), (Equation 4), (Equation 12), (Equation 14) ), (Equation 18) and (Equation 19). The conditions represented by these formulas have been found by the inventors' studies. As in the first embodiment, an example of the boundary line derived from the analysis of the pressure loss and the core stability of the fuel assembly 1 K of the present embodiment is shown in FIG. The boundary line L8 shown in Fig. 22 is the boundary line for the pressure loss when 10 short fuel rods 2B are arranged in 1K of the fuel assembly including the inside of the outermost fuel rod array. is there. Similarly, boundary line M8 is a boundary line for core stability when 12 short fuel rods 2B are arranged. In this embodiment, since all the short fuel rods 2B are arranged at positions where the effect of improving the void coefficient is large, that is, at the position in the outermost layer of the fuel rod array and at the position adjacent to the water port, the core The condition for stability (Equation 19) is different from the condition for core stability in Example 3 (Equation 13). If the core stability is the same, the total cross-sectional area of the water head 3C in this embodiment is smaller than that of the second embodiment. On the other hand, the condition (Equation 14) determined from the pressure loss in this embodiment is the same as that in Embodiment 3 without being affected by the arrangement of the short fuel rods. Also, the upper limit of Awr / Ach is the value indicated by (Equation 31) as in the third embodiment. In the present embodiment, the number of short fuel rods 2B required was in the range of 7 to 20 by the same study as in the first embodiment.
第 2 2図においてハッチングを施した領域は、 1 0本の短尺燃料棒 2 Bが第 2 1 図のように配置された場合において （数 1 )， （数 4)， （数 1 2 )， （数 1 4 ) 及び （数 1 9 ) を満足する領域である。 この領域にな るように、 L p Z L f 及び水ロッ ド 3 Eの横断面積が設定される。 しか しながら、 （数 1 8 ) を満足する場合、 すなわち 7 ≤ n≤ 2 0の場合に おいても、 （数 1 )， （数 4 )， （数 1 2 )， （数 1 4 ) 及び （数 1 9 ) を満 足させる領域がそれぞれ存在する。 In FIG. 22, the hatched areas indicate (Equation 1), (Equation 4), (Equation 1 2), and (Equation 1) when the ten short fuel rods 2B are arranged as shown in FIG. This is an area that satisfies (Equation 14) and (Equation 19). The cross-sectional area of LpZLf and water rod 3E is set to be in this area. However, if (Equation 1 8) is satisfied, that is, if 7 ≤ n≤ 20 Also, there are regions that satisfy (Equation 1), (Equation 4), (Equation 12), (Equation 14), and (Equation 19), respectively.
本実施例によれば、 第 4実施例と同様の効果が得られる。 また、 短尺 燃料棒は、 最外層内の位置及び水ロ ッ ドに隣接した位置、 または最外層 内の位置のみに配置すれば、 第 2 1 図と異なる配置と しても、 更に、 第 2 2図に示す燃料集合体 1 Lと してもよい。 燃料集合体 1 Lは、 燃料集 合体 1 Kにおいて水口ッ ド 3 Eを横断面が矩形の水ロ ッ ド 3 Fに替えた ものである。 水ロッ ド 3 Fは、 水ロ ッ ド 3 Eと同じ位置に配置される。 産業上の利用可能性  According to this embodiment, the same effects as in the fourth embodiment can be obtained. In addition, if the short fuel rods are arranged at the position in the outermost layer and the position adjacent to the water rod, or only at the position in the outermost layer, even if the arrangement is different from that in Fig. 21, The fuel assembly 1 L shown in Fig. 2 may be used. The fuel assembly 1L is obtained by replacing the water port 3E in the fuel assembly 1K with a water rod 3F having a rectangular cross section. Water rod 3F is located at the same position as water rod 3E. Industrial applicability
本発明の燃料集合体は、 沸騰水型原子炉の炉心に装荷するのに好都合 である。  The fuel assembly of the present invention is convenient for loading into the core of a boiling water reactor.

Claims

請 求 の 範 囲 The scope of the claims
1 . 複数の第 1 燃料棒、 及び前記第 1 燃料棒よ り も長さが短い複数の第 2燃料棒を有し、 これらの燃料棒が 1 0行 1 0列の燃料棒配列内に配置 され、 8本の燃料棒が配置可能な領域を占有する複数の水口 ッ ドを備え、 前記第 2燃料棒が最外層の燃料棒配列内に配置されていない燃料集合体 であって、 1. A plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods, and these fuel rods are arranged in a 10 × 10 fuel rod array. A fuel assembly, comprising a plurality of water inlets occupying an area where eight fuel rods can be arranged, wherein the second fuel rods are not arranged in an outermost fuel rod array;
前記水口 ッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部での冷 却材流路の横断面積を A c h， 前記第 1 燃料棒の燃料有効長を L f 、 前 記第 2燃料棒の本数を n， 前記第 2燃料棒の燃料有効長を L p、 及び平 均燃焼度を B ( GW d / t ) と したと き、  The sum of the cross-sectional areas of the water port is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach, the active fuel length of the first fuel rod is Lf, and the second fuel is When the number of rods is n, the active fuel length of the second fuel rod is L p, and the average burnup is B (GW d / t),
B > 6 0  B> 6 0
1 5≤ n≤ 2 0 ( n ： 整数）  1 5≤ n≤ 2 0 (n: integer)
Aw r /A c h≤ 0. 1 4 9  Aw r / A c h ≤ 0.1 4 9
L p / L f ≥ 1 1 / 2  L p / L f ≥ 1 1/2
Aw r /A c h ( 3. 0 0 X 1 0 - 4 X n 2 + 6. 0 0 X 1 0 -4 Aw r / A ch (3. 0 0 X 1 0 - 4 X n 2 + 6. 0 0 X 1 0 - 4
x n - 1 . 2 x 1 0 "2) x (L p / L f - l )xn-1.2 .2 x 1 0 " 2 ) x (L p / L f-l)
+ 1 . 7 5 X 1 0 _ 1 + 1.75 X 10 0 _ 1
A r /A c h < ( 8. 6 3 X 1 0 — 4 X n 2 — 6. 0 9 X 1 0 - 2 X n A r / A ch <(8. 6 3 X 1 0 - 4 X n 2 - 6. 0 9 X 1 0 - 2 X n
+ 1. 3 3 x l 0 - 1) X (L p / L f - 8. 3 2 + 1. 3 3 xl 0 - 1 ) X (L p / L f - 8. 3 2
X 1 0 - " X 1 0-"
を満足する こと を特徴とする燃料集合体。 A fuel assembly characterized by satisfying the following.
2 . ク レーム 1 において、 前記第 2燃料棒の一部が前記水ロ ッ ドに隣接 して配置され、 残り の前記第 2燃料棒は外側から 2層目の燃料棒配列内 に配置されている燃料集合体。  2. In claim 1, a part of the second fuel rod is disposed adjacent to the water rod, and the remaining second fuel rod is disposed in a second-layer fuel rod arrangement from the outside. Fuel assembly.
3. ク レーム 1 又は 2 において、 前記水ロ ッ ドは 4本の燃料棒が配置可 能な領域に配置される横断面積を有し、 2本の前記水口 ッ ドを備えてい る燃料集合体。 3. In claim 1 or 2, the water rod can accommodate 4 fuel rods A fuel assembly having a cross-sectional area arranged in an active area and comprising two of said water ports.
4. 複数の第 1燃料棒、 及び前記第 1燃料棒よ り も長さが短い複数の第 2燃料棒を有し、 これらの燃料棒が 1 0行 1 0列の燃料棒配列内に配置 され、 9本の燃料棒が配置可能な領域を占有する複数の水口 ッ ドを備え . 前記第 2燃料棒が最外層の燃料棒配列内に配置されていない燃料集合体 であって、  4. It has a plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods, and these fuel rods are arranged in a 10 × 10 fuel rod array. A plurality of water ports occupying an area where nine fuel rods can be arranged. The fuel assembly wherein the second fuel rod is not arranged in the outermost fuel rod array,
前記水口 ッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部での冷 却材流路の横断面積を A c h， 前記第 1燃料棒の燃料有効長を L f ， 前 記第 2燃料棒の本数を n， 前記第 2燃料棒の燃料有効長を L p、 及び平 均燃焼度を B ( G W d / t ) と したとき、  Awr is the sum of the cross-sectional areas of the water inlet, Ach is the cross-sectional area of the coolant passage below the fuel assembly, Lf is the active fuel length of the first fuel rod, and the second fuel is When the number of rods is n, the active fuel length of the second fuel rod is L p, and the average burnup is B (GW d / t),
B > 6 0  B> 6 0
1 0≤ n 2 0 ( n ： 整数）  1 0≤ n 2 0 (where n is an integer)
Aw r /A c h 0. 1 6 9  Aw r / A c h 0.1 6 9
L p / L f 1 1 / 2 4  L p / L f 1 1/2 4
Aw r A c h≥ ( 2. 6 5 X 1 0— 4 X n 2 + 2. 1 5 X 1 0- 3 X n Aw r A ch≥ (2. 6 5 X 1 0- 4 X n 2 + 2. 1 5 X 1 0- 3 X n
— 1. 9 6 X 1 0 - 2) X (L p / L f — 1 ) - 1. 9 6 X 1 0 - 2) X (L p / L f - 1)
+ 1. 6 8 X 1 0 - 1 + 1. 6 8 X 1 0 - 1
Aw r /A c h≤ ( 7. 1 X 1 0 " x n 2 - 5. 6 3 X 1 0- 2 X n Aw r / A ch≤ (7. 1 X 1 0 "xn 2 - 5. 6 3 X 1 0- 2 X n
+ 8. 8 4 X 1 0 _2) X (L p Z L f — 8. 5 2 + 8. 8 4 X 1 0 _ 2) X (L p ZL f - 8. 5 2
X 1 0 -】）  X 10 0-】)
を満足する こと を特徴とする燃料集合体。 A fuel assembly characterized by satisfying the following.
5. ク レーム 4において、 前記第 2燃料棒は外側から 2層目の燃料棒配 列内に配置されている燃料集合体。  5. The fuel assembly according to claim 4, wherein the second fuel rod is disposed in a fuel rod array in a second layer from the outside.
6. ク レーム 4又は 5において、 前記水ロ ッ ドは、 前記燃料集合体の軸 心の位置から、 制御棒に面するコーナー部とは反対側にずれて配置され た燃料集合体。 6. In claims 4 or 5, the water rod is the shaft of the fuel assembly. A fuel assembly that is offset from the center of the core to the opposite side of the corner facing the control rod.
7. 複数の第 1燃料棒、 及び前記第 1燃料棒よ り も長さが短い複数の第 2燃料棒を有し、 これらの燃料棒が 1 0行 1 0列の燃料棒配列内に配置 され、 1 0本の燃料棒が配置可能な領域を占有する複数の水ロ ッ ドを備 え、 前記第 2燃料棒が最外層の燃料棒配列内に配置されていない燃料集 合体であって、'  7. It has a plurality of first fuel rods and a plurality of second fuel rods shorter in length than the first fuel rods, and these fuel rods are arranged in a 10 × 10 fuel rod array. A fuel assembly having a plurality of water rods occupying an area where ten fuel rods can be arranged, wherein the second fuel rods are not arranged in the outermost fuel rod array. , '
前記水口 ッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部での冷 却材流路の横断面積を A c h， 前記第 1燃料棒の燃料有効長を L f ， 前 記第 2燃料棒の本数を n， 前記第 2燃料棒の燃料有効長を L p、 及び平 均燃焼度を B ( G W d / t ) と したと き、  Awr is the sum of the cross-sectional areas of the water inlet, Ach is the cross-sectional area of the coolant passage below the fuel assembly, Lf is the active fuel length of the first fuel rod, and the second fuel is When the number of rods is n, the active fuel length of the second fuel rod is L p, and the average burnup is B (GW d / t),
B≥ 6 0  B≥ 6 0
9 ≤ n≤ 2 0 ( n ： 整数）  9 ≤ n ≤ 2 0 (where n is an integer)
Aw r /A c h 0. 1 9 0  Aw r / A c h 0.19
L p / L f ≥ 1 1 / 2  L p / L f ≥ 1 1/2
A w r / A c h > ( 2. 3 1 X 1 0— 4 X n 2 + 3. 6 9 X 1 0— 3 X n A wr / A ch> (2. 3 1 X 1 0- 4 X n 2 + 3. 6 9 X 1 0- 3 X n
- 2. 7 l X l O "2) x (L p / L f - l ) -2.7 l X l O " 2 ) x (L p / L f-l)
+ 1. 6 0 X 1 0 - 1 + 1. 6 0 X 1 0 - 1
Aw r /A c h < ( 6. 1 8 X 1 0— 4 X n 2 — 5. 1 8 X 1 0- 2 X n Aw r / A ch <(6. 1 8 X 1 0- 4 X n 2 - 5. 1 8 X 1 0- 2 X n
+ 4. 1 X 1 0 ~2) X ( L p / L f - 8. 7 2+ 4.1 X 10 ~ 2 ) X (L p / L f -8.72
X 1 0 -リ X 10 0-
を満足する こと を特徴とする燃料集合体。 A fuel assembly characterized by satisfying the following.
8. ク レーム 7 において、 前記第 2燃料棒の少な く とも一部が、 外側か ら 2層目の燃料棒配列内に配置されている燃料集合体。  8. The fuel assembly according to claim 7, wherein at least a part of the second fuel rod is disposed in a fuel rod array of a second layer from the outside.
9. ク レーム 7又は 8 において、 前記水ロ ッ ドは、 制御棒に面するコー ナ一部に対する対角線と直交する他の対角線上に配置されている燃料集 合体。 9. In claim 7 or 8, the water rod is installed on the cord facing the control rod. Fuel assemblies located on the other diagonal that is orthogonal to the diagonal to some of the fuel assemblies.
I 0. 複数の第 1燃料棒、 及び前記第 1燃料棒よ リ も長さが短い複数の 第 2燃料棒を有し、 これらの燃料棒が 1 0行 1 0列の燃料棒配列内に配 置され、 8本の燃料棒が配置可能な領域を占有する複数の水口 ッ ドを備 え、 前記第 2燃料棒が、 最外層の燃料棒配列内の位置及び前記水ロ ッ ド に隣接した位置の両方、 及び最外層の燃料棒配列内の位置のみ、 のいず れかに配置された燃料集合体であって、  I 0. There are a plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods, and these fuel rods are arranged in a 10 × 10 fuel rod array. A plurality of water rods arranged to occupy an area where eight fuel rods can be arranged, wherein the second fuel rods are located in the outermost fuel rod array and adjacent to the water rods. Fuel assemblies located in either of the above positions, and only in the outermost fuel rod array,
前記水口 ッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部での冷 却材流路の横断面積を A c h， 前記第 1燃料棒の燃料有効長を L f ， 前 記第 2燃料棒の本数を n， 前記第 2燃料棒の燃料有効長を L p、 及び平 均燃焼度を B ( GW d / t ) と したと き、  Awr is the sum of the cross-sectional areas of the water inlet, Ach is the cross-sectional area of the coolant passage below the fuel assembly, Lf is the active fuel length of the first fuel rod, and the second fuel is When the number of rods is n, the active fuel length of the second fuel rod is L p, and the average burnup is B (GW d / t),
B≥ 6 0  B≥ 6 0
9 ≤ n < 2 0 ( n ： 整数）  9 ≤ n <20 (where n is an integer)
Aw r /A c h≤ 0. 1 9  Aw r / A c h≤ 0.1 9
L p / L f ≥ 1 1 / 2  L p / L f ≥ 1 1/2
Aw r /A c h≥ ( 3. 0 0 x 1 0 X n 2 + 6. 0 0 x i 0"4 x n Aw r / A ch≥ (3. 0 0 x 1 0 X n 2 + 6. 0 0 xi 0 "4 xn
+ 6. 8 0 X 1 0 :) x ( L p / L f - 1 ) + 6. 8 0 X 1 0: ) x (L p / L f - 1)
+ 1. 7 5 X 1 0  +1.75 X 10
Aw r /A c h≤ ( 8. 6 3 x 1 0— 4 X n 2— 6. 0 9 x 1 0 "2 x n Aw r / A ch≤ (8.6 3 x 1 0— 4 X n 2 — 6.09 x 1 0 " 2 xn
+ 1. 3 3 X 1 0 -!) x (L p / L f - 8. 3 2 X 1 0 -リ + 1.33X10- ! ) X (Lp / Lf-8.32X10-
を満足すること を特徴とする燃料集合体。 A fuel assembly characterized by satisfying the following.
1 1 . ク レーム 1 0において、 2層目の燃料棒配列内には前記第 1燃料 棒のみが配置されている燃料集合体。 11. The fuel assembly according to claim 10, wherein only the first fuel rod is disposed in the second-layer fuel rod array.
1 2. クレーム 1 0又は 1 1 において、 前記水口ッ ドは 4本の燃料棒が 配置可能な領域に配置される横断面積を有し、 2本の前記水口ッ ドを備 えている燃料集合体。 1 2. In Claim 10 or 11, the water port head has a cross-sectional area arranged in an area where four fuel rods can be disposed, and the fuel assembly having two water port heads. .
1 3 . 複数の第 1燃料棒、 及び前記第 1燃料棒よ りも長さが短い複数の 第 2燃料棒を有し、 これらの燃料棒が 1 0行 1 0列の燃料棒配列内に配 置され、 9本の燃料棒が配置可能な領域を占有する複数の水口ッ ドを備 え、 前記第 2燃料棒が、 最外層の燃料棒配列内の位置及び前記水ロッ ド に隣接した位置の両方、 及び最外層の燃料棒配列内の位置のみ、 のいず れかに配置された燃料集合体であって、  13. A plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods, and these fuel rods are arranged in a fuel rod array of 10 rows and 10 columns. A plurality of water inlet rods arranged to occupy an area where nine fuel rods can be disposed, wherein the second fuel rod is located in the outermost fuel rod array and adjacent to the water rod. A fuel assembly located in either of the positions, and only in the outermost fuel rod array,
前記水口ッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部での冷 却材流路の横断面積を A c h , 前記第 1燃料棒の燃料有効長を L ί ， 前 記第 2燃料棒の本数を η， 前記第 2燃料棒の燃料有効長を L ρ、 及び平 均燃焼度を Β ( GW d / t ) としたとき、  The sum of the cross-sectional areas of the water port is Awr, the cross-sectional area of the coolant flow path below the fuel assembly is Ach, the active fuel length of the first fuel rod is L L, and the second fuel is Assuming that the number of rods is η, the active fuel length of the second fuel rod is L ρ, and the average burnup is Β (GW d / t),
B≥ 6 0  B≥ 6 0
8 < n≤ 2 0 ( n ： 整数）  8 <n ≤ 20 (n: integer)
Aw r /A c h≤ 0. 1 6 9  Aw r / A c h≤ 0.1.6 9
L p / L f > 1 1 / 2 4  L p / L f> 1 1/2 4
Aw r /A c h≥ ( 2. 6 5 X 1 0 X n 2 + 2. 1 5 X 1 0 X n Aw r / A ch≥ (2. 6 5 X 1 0 X n 2 + 2. 1 5 X 1 0 X n
+ 6. 0 4 X 1 0 "2) x (L p / L 1 ) +6.04 X 10 " 2 ) x (L p / L 1)
+ 1 . 6 8 X 1 0— 1 + 1.6 8 X 1 0— 1
Aw r /A c h ≤ ( 7. 1 X 1 0 - 4 X n 2 — 5. 6 3 X 1 0 "2 X n Aw r / A ch ≤ (7. 1 X 1 0 - 4 X n 2 - 5. 6 3 X 1 0 "2 X n
+ 8. 8 4 X 1 0 "2) X ( L p / L f - 8. 5 2+8.84 X 10 " 2 ) X (L p / L f -8.5 2
X 1 0 リ X 10 0
を満足することを特徴とする燃料集合体。 A fuel assembly characterized by satisfying the following.
1 4. ク レーム 1 3 において、 2層目の燃料棒配列内には前記第 1燃料 棒のみが配置されている燃料集合体。 1 4. In claim 13, the first fuel A fuel assembly where only rods are located.
1 5. ク レーム 1 3又は 1 4において、 前記水ロ ッ ドは、 前記燃料集合 体の軸心の位置から、 制御棒に面するコーナー部とは反対側にずれて配 置された燃料集合体。  1 5. In claim 13 or 14, the water rod is a fuel assembly that is displaced from the axial center of the fuel assembly to the opposite side of the corner facing the control rod. body.
1 6 . 複数の第 1燃料棒、 及び前記第 1燃料棒よ リ も長さが短い複数の 第 2燃料棒を有し、 これらの燃料棒が 1 0行 1 0列の燃料棒配列内に配 置され、 1 0本の燃料棒が配置可能な領域を占有する複数の水口 ッ ドを 備え、 前記第 2燃料棒が、 最外層の燃料棒配列内の位置及び前記水口 ッ ドに隣接 した位置の両方、 及び最外層の燃料棒配列内の位置のみ、 のい ずれかに配置された燃料集合体であつて、  16. A plurality of first fuel rods and a plurality of second fuel rods having a shorter length than the first fuel rods, and these fuel rods are arranged in a 10 × 10 fuel rod array. A plurality of water rods arranged to occupy an area where ten fuel rods can be arranged, wherein the second fuel rods are located in the outermost fuel rod array and adjacent to the water rods. Both positions, and only those positions within the outermost fuel rod array, that are located in either of the fuel assemblies,
前記水口 ッ ドの横断面積の総和を Aw r ， 前記燃料集合体下部での冷 却材流路の横断面積を A c h， 前記第 1燃料棒の燃料有効長を L f ， 前 記第 2燃料棒の本数を n， 前記第 2燃料棒の燃料有効長を L p、 及び平 均燃焼度を B ( GW d / t ) と したと き、  Awr is the sum of the cross-sectional areas of the water inlet, Ach is the cross-sectional area of the coolant passage below the fuel assembly, Lf is the active fuel length of the first fuel rod, and the second fuel is When the number of rods is n, the active fuel length of the second fuel rod is L p, and the average burnup is B (GW d / t),
B > 6 0  B> 6 0
7 ≤ n < 2 0 ( n : 整数）  7 ≤ n <2 0 (where n is an integer)
Aw r /A c h≤ 0. 1 9 0  Aw r / A c h ≤ 0.19
L p / L f > 1 1 / 2  L p / L f> 1 1/2
Aw r /A c h ( 2. 3 1 X 1 0—4 X n 2 + 3. 6 9 x 1 0 - 3 X n Aw r / A ch (2. 3 1 X 1 0- 4 X n 2 + 3. 6 9 x 1 0 - 3 X n
+ 5. 2 9 X 1 0 "2) x (L p / L f - l ) + 5.2 9 X 10 " 2 ) x (L p / L f-l)
+ 1. 6 0 X 1 0 - 1 + 1. 6 0 X 1 0 - 1
Aw r /A c h < ( 6. 1 8 X 1 0— 4 X n 2 — 5. 1 8 X 1 0— 2 x n Aw r / A ch <(6. 1 8 X 1 0- 4 X n 2 - 5. 1 8 X 1 0- 2 xn
+ 4. 4 1 X 1 0 -2) x (L p / L f - 8. 7 2+ 4. 4 1 X 1 0 - 2) x (L p / L f - 8. 7 2
X 1 0 -リ X 10 0-
を満足する こと を特徴とする燃料集合体。 A fuel assembly characterized by satisfying the following.
1 7. ク レーム 1 6 において、 2層目の燃料棒配列内には前記第 1燃料 棒のみが配置されている燃料集合体。 1 7. A fuel assembly according to claim 16, wherein only the first fuel rod is disposed in the second-layer fuel rod array.
1 8 . ク レーム 1 6又は 1 7 において、 前記水ロ ッ ドは、 制御棒に面す るコーナー部に対する対角線と直交する他の対角線上に配置されている 燃料集合体。  18. The fuel assembly according to claim 16 or 17, wherein the water rod is disposed on another diagonal line orthogonal to a diagonal line to a corner portion facing the control rod.
PCT/JP1999/005354 1999-09-29 1999-09-29 Fuel assembly WO2001024196A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005195589A (en) * 2003-12-31 2005-07-21 Global Nuclear Fuel Americas Llc Method for clustering and distributing partial length rods of nuclear reactor fuel assembly

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05232273A (en) * 1991-12-26 1993-09-07 Hitachi Ltd Fuel assembly and reactor core
JPH06102384A (en) * 1992-09-18 1994-04-15 Hitachi Ltd Fuel assembly and reactor core
JPH06294879A (en) * 1993-04-12 1994-10-21 Hitachi Ltd Reactor fuel assembly and upper tie plate
JPH07301688A (en) * 1994-05-09 1995-11-14 Toshiba Corp Fuel assembly
JPH08292281A (en) * 1995-04-20 1996-11-05 Toshiba Corp Fuel assembly for boiling water type reactor
JPH10115690A (en) * 1997-10-31 1998-05-06 Hitachi Ltd Fuel assembly
JPH10288687A (en) * 1997-02-13 1998-10-27 Hitachi Ltd Fuel assembly
JPH10311889A (en) * 1998-06-12 1998-11-24 Hitachi Ltd Fuel assembly
JPH10325890A (en) * 1997-05-23 1998-12-08 Hitachi Ltd Fuel assembly
JPH11194190A (en) * 1992-08-06 1999-07-21 Hitachi Ltd Fuel assembly

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05232273A (en) * 1991-12-26 1993-09-07 Hitachi Ltd Fuel assembly and reactor core
JPH11194190A (en) * 1992-08-06 1999-07-21 Hitachi Ltd Fuel assembly
JPH06102384A (en) * 1992-09-18 1994-04-15 Hitachi Ltd Fuel assembly and reactor core
JPH06294879A (en) * 1993-04-12 1994-10-21 Hitachi Ltd Reactor fuel assembly and upper tie plate
JPH07301688A (en) * 1994-05-09 1995-11-14 Toshiba Corp Fuel assembly
JPH08292281A (en) * 1995-04-20 1996-11-05 Toshiba Corp Fuel assembly for boiling water type reactor
JPH10288687A (en) * 1997-02-13 1998-10-27 Hitachi Ltd Fuel assembly
JPH10325890A (en) * 1997-05-23 1998-12-08 Hitachi Ltd Fuel assembly
JPH10115690A (en) * 1997-10-31 1998-05-06 Hitachi Ltd Fuel assembly
JPH10311889A (en) * 1998-06-12 1998-11-24 Hitachi Ltd Fuel assembly

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005195589A (en) * 2003-12-31 2005-07-21 Global Nuclear Fuel Americas Llc Method for clustering and distributing partial length rods of nuclear reactor fuel assembly

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