CN118094364A - Method for evaluating power inclination state of quadrant of reactor core - Google Patents

Abstract

The invention relates to a method for evaluating the power inclination state of a quadrant of a reactor core, which comprises the following steps: s1, acquiring position information and deformation data corresponding to each fuel assembly of a previous circulating reactor core; s2, acquiring the corresponding displacement of the fuel assembly in the reactor core based on the deformation data of the fuel assembly; s3, correcting a modeling model corresponding to the current circulating reactor core based on the displacement of the fuel assembly and the position information of the fuel assembly, so as to obtain reactor core power inclination data corresponding to the reactor according to the corrected modeling model; s4, obtaining an evaluation result of the reactor core power inclination state according to the reactor core power inclination data. By implementing the invention, the quadrant power inclined state of the nuclear reactor during operation can be deduced by a simple means, so that the operation safety of the reactor core is further ensured.

Description

Method for evaluating power inclination state of quadrant of reactor core

Technical Field

The invention relates to the technical field of nuclear power, in particular to a method for evaluating the power inclination state of a quadrant of a reactor core.

Background

The inclination of the power of the quadrants of the reactor core means that the power level of each quadrant area of the reactor core is asymmetric, and certain areas have higher phenomena; the method is characterized in that systematic and regional deviation exists between theoretical calculated power and actual reactor core power. The reason for this phenomenon is numerous and complex, and it is difficult to capture the power tilt state of the core before the core starts; only during the operation of the core, the experimental measurement of the flux map is carried out, so that the power inclined state can be found. Once the reactor core scheme is determined, the power inclination state after the reactor core is started cannot be effectively controlled, and once the value exceeds the value, the safety and the economy of the operation of the reactor core are restricted. Therefore, the control of the power ramp is designed mainly by the scheme of the reloading design stage.

In the prior art, the consideration of power tilt in the refueling design stage is mainly based on historical experience, by intentionally and qualitatively evaluating possible power tilt states and by adjusting the core loading scheme, deliberately suppressing such possible trends. The process is mainly based on personal experience, has great influence on human factors and lacks an effective means of quantitative evaluation.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for evaluating the power tilting state of the quadrant of a reactor core aiming at the part of technical defects in the prior art.

The technical scheme adopted for solving the technical problems is as follows: a method for evaluating the power inclination state of a quadrant of a reactor core is constructed, which comprises the following steps:

S1, acquiring position information and deformation data corresponding to each fuel assembly in a previous circulating reactor core;

s2, acquiring the displacement of the fuel assembly corresponding to the reactor core based on the deformation data of the fuel assembly;

S3, correcting a modeling model corresponding to the reactor core in the current circulation based on the displacement of the fuel assembly and the position information of the fuel assembly, so as to obtain reactor core power inclination data corresponding to the reactor according to the corrected modeling model;

s4, obtaining an evaluation result of the reactor core power inclination state according to the reactor core power inclination data.

Preferably, in the method for evaluating a quadrant power tilt state of a reactor core according to the present invention, in the step S1, position information and deformation data corresponding to each fuel assembly in a previous cycle core are obtained; comprising the following steps:

and in the refueling and overhaul process of the nuclear power unit, acquiring the position information of each fuel assembly in the reactor core and the deformation data of the fuel assemblies in the previous cycle.

Preferably, in the method for evaluating a power tilt state of a quadrant of a reactor core according to the present invention, the method further includes:

And acquiring the inherent deformation characteristics corresponding to each position in the reactor core, so as to acquire the deformation data of the fuel assembly in the previous cycle according to the position information of the fuel assembly in the previous cycle and the inherent deformation characteristics corresponding to the position.

Preferably, in the method for evaluating a power tilt state of a quadrant of a reactor core according to the present invention, the method further includes:

And acquiring the inherent deformation characteristic based on historical data in the overhaul process of the nuclear power unit, wherein the historical data comprises the acquired position information of each fuel assembly in the reactor core and the deformation data of the fuel assembly in the refueling overhaul process of the nuclear power unit each time.

Preferably, in the method for evaluating a power-in-quadrant state of a reactor core according to the present invention, in the step S2, the displacement amount of the fuel assembly in the core is acquired based on deformation data of the fuel assembly; comprising the following steps:

and converting the deformation data of the fuel assembly based on a preset conversion function to obtain the displacement of the fuel assembly relative to a preset position.

Preferably, in the method for evaluating a power tilt state of a quadrant of a reactor core according to the present invention, the preset transfer function is: f2 =f1/K, where F1 is deformation data of the fuel assembly, F2 is displacement amount of the fuel assembly, and K is a constant.

Preferably, in the method for evaluating a power tilt state of a quadrant of a reactor core of a reactor according to the present invention, in the step S3, the modeling model corresponding to the core of the current cycle is modified based on the displacement amount of the fuel assembly and the position information of the fuel assembly, so as to obtain power tilt data of the reactor corresponding to the reactor according to the modified modeling model; comprising the following steps:

Gaps of the fuel assemblies in the reactor core in the current cycle are reset based on the displacement amounts of the fuel assemblies and the position information of the fuel assemblies, so that modeling models corresponding to the reactor core are updated according to the new gaps, and the reactor core power inclination data are acquired.

In the method for evaluating a power tilt state of a quadrant of a reactor core according to the present invention, in step S4, the step of obtaining the result of evaluating the power tilt state of the reactor core from the power tilt data includes:

judging whether the reactor core power inclination data is larger than a preset value, judging that the reactor core power inclination state is reasonable when the reactor core power inclination data is smaller than the preset value, and otherwise judging that the reactor core power inclination state is unreasonable.

Preferably, in the method for evaluating a power tilt state of a quadrant of a reactor core according to the present invention, the method further includes:

And when the reactor core power inclination state is judged to be unreasonable, acquiring the power change state of the fuel assembly so as to adjust the position of the fuel assembly according to the power change state of the fuel assembly.

Preferably, in the method for evaluating a power tilt state of a quadrant of a reactor core according to the present invention, the method further includes:

When the power change state of the fuel assembly becomes larger, acquiring the power change state of the fuel assembly at the symmetrical position corresponding to the fuel assembly, and acquiring the fuel assembly with smaller power level for exchanging;

And when the power change state of the fuel assembly is smaller, acquiring the power change state of the fuel assembly at the symmetrical position corresponding to the fuel assembly, and acquiring the fuel assembly with larger power level for replacement.

The method for evaluating the power inclined state of the quadrant of the reactor core has the following beneficial effects: the quadrant power inclined state of the nuclear reactor during operation can be deduced through a simple means, so that the operation safety of the nuclear reactor is further ensured.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic diagram of a method for evaluating a power ramp condition in a quadrant of a reactor core in accordance with the present invention;

FIG. 2 is a schematic illustration of core gap variation;

FIG. 3 is a schematic view of a first embodiment of a core layout;

FIG. 4 is a schematic illustration of a variation of a fuel assembly;

FIG. 5 is a schematic of the power distribution of a normal core;

FIG. 6 is a schematic illustration of the power distribution of the core resulting from deformation of the fuel assemblies;

FIG. 7 is a schematic illustration of the degree of power change of the core as a result of deformation of the fuel assembly;

FIG. 8 is a schematic diagram of a fuel assembly position adjustment process.

Detailed Description

For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings.

As shown in fig. 1, in a first embodiment of a reactor core quadrant power tilt state evaluation method of the present invention, the method includes the steps of: s1, acquiring position information and deformation data corresponding to each fuel assembly in the previous cycle reactor core. In particular, in a reactor, the fuel assemblies typically have a fixed mounting position in the core. In a reactor, the reactor power distribution will be made satisfactory according to the inherent design. However, during operation, the fuel assemblies are subject to deformation for various reasons, which typically affects the power distribution of the core. That is, in each cycle, the deformation data of the core will have an effect on the next cycle. Analysis of the next cycle based on deformation data of the previous cycle is required. Wherein the fuel assemblies at different locations have different power distributions in the reactor, and the deformation thereof has different effects on the power distribution of the entire reactor. It is therefore necessary to acquire deformation data of the fuel assemblies at different positions, respectively, for analysis. That is, it is understood that it is necessary to acquire both the positional information of the fuel assembly and the deformation data corresponding to the fuel assembly.

In one embodiment, in the step S1, the position information and deformation data corresponding to each fuel assembly in the previous circulating core are obtained; comprising the following steps: and in the refueling and overhaul process of the nuclear power unit, acquiring the position information of each fuel assembly in the reactor core and the deformation data of the fuel assemblies in the previous cycle. And in the process of the refueling overhaul of the nuclear power plant, all the fuel assemblies are discharged and then hoisted to a specific area, and the deformation measurement of the fuel assemblies is carried out to obtain the deformation condition of each fuel assembly at different grid heights. The deformation measurement method of the fuel assembly can adopt the current common methods such as ultrasonic wave, laser photography and the like. In some embodiments, only deformation data for a particular location of the fuel assembly may be acquired, such as at an 8-layer grid location of the fuel assembly. That is, one fuel assembly is high and at different heights, the deformation is inconsistent. There are typically 8 spacer grids in axial height for common fuel assemblies (e.g., those used in CPR1000 reactors). In measurement, the measurement can be performed at these 8 positions.

In one embodiment, the intrinsic deformation characteristics corresponding to each location in the core may also be obtained to obtain deformation data for the fuel assembly of the previous cycle based on the location information of the fuel assembly and the intrinsic deformation characteristics corresponding to that location. That is, in the in-reactor environment of a reactor, the fuel assembly deformation at each location tends to have some inherent deformation tendency, and deformation measurements for each location may be based on multiple cycles as an inherent deformation profile of the unit. And obtaining the inherent deformation characteristic of each position of the reactor core of the unit. Deformation data for the fuel assembly at the location may be obtained based on the intrinsic deformation characteristics corresponding to the location. It will be appreciated that the deformation data for each fuel assembly during the previous cycle of that fuel assembly can be derived from the position information of that fuel assembly in the core. It will be appreciated herein that the deformation data is data of the fuel assembly after it has been optimized relative to the previous core. For example, the deformation may be caused for one cycle of acquisition.

Optionally, in the method for evaluating a power tilt state of a quadrant of a reactor core of a reactor according to the present invention, the intrinsic deformation characteristic may be obtained based on historical data during a major repair of a nuclear power unit, where the historical data includes positional information of each fuel assembly in the core and deformation data of the fuel assembly obtained during each major repair of a nuclear power unit. That is, it is possible to perform measurement once at each refueling and overhaul stage, and perform data processing on the deformation condition at each position, that is, the past year data, for example, taking an average value as an inherent deformation characteristic of the unit. The first measurement does not need to take an average value, and the average value is taken after multiple measurements.

S2, acquiring the displacement of the fuel assembly corresponding to the reactor core based on the deformation data of the fuel assembly. Specifically, if the fuel assembly is deformed, its position within the core is moved. At this time, the displacement of the fuel assembly in the core can be obtained from the deformation data of the fuel assembly. In the displacement amount calculation process, the deformation of the entire fuel assembly can be decomposed into displacements in both X and Y directions, which can be considered independently in the XY direction (i.e., horizontal direction). In the axial direction (i.e., z-direction), the cells at the same cell height are segmented according to the cell height, with the amount of deformation at that cell. The deformation amount can affect the position of the fuel assembly in the reactor core finally, and then the corresponding displacement amount of the fuel assembly in the reactor core can be obtained based on the deformation amount.

Optionally, in the step S2, the displacement amount of the fuel assembly corresponding to the core is obtained based on the deformation data of the fuel assembly; comprising the following steps: and converting the deformation data of the fuel assembly based on a preset conversion function to obtain the displacement of the fuel assembly relative to a preset position. The displacement caused by the deformation of the fuel assembly has a specific rule, so that the deformation data of the fuel assembly can be converted based on a preset conversion function to obtain a corresponding displacement. For example, the core has 157 locations for arranging the components, the center of each location being theoretically fixed; in practice, however, the center position of the fuel assembly will shift, i.e., displace, due to deformation of the fuel assembly. Wherein, the preset transfer function is: f2 =f1/K, where F1 is deformation data of the fuel assembly, F2 is displacement amount of the fuel assembly, and K is a constant. In an embodiment, the value of K may be 1.4, and the value may be adjusted according to different actual scenes.

And S3, correcting a modeling model corresponding to the reactor core in the current cycle based on the displacement of the fuel assembly and the position information of the fuel assembly, so as to obtain reactor core power inclination data corresponding to the reactor according to the corrected modeling model. That is, after deformation of the fuel assembly, the parameters of the fuel assembly will also change, such as the gap between the fuel assembly and the fuel assembly at different heights. The power distribution of the core also changes from the previous design values, and in the course of performing a new core power distribution calculation in a new cycle, calculation based on new parameters such as clearance data is required, i.e., the clearances between fuel assemblies in the core calculation model are adjusted accordingly to obtain the latest core power distribution. The new cycle may be understood as a cycle to be performed in which the gap of each fuel assembly in the core may be reset based on the displacement amount of the fuel assembly and the position information of the fuel assembly to update the corresponding modeling model of the core according to the new gap to acquire the core power inclination data. The specific process is to reset the gaps between the individual fuel assembly locations during the core modeling process. The change in fuel assembly clearances will affect the local moderation conditions, causing a change in core power distribution; when the deformation distribution of the fuel assembly is in a certain directional distribution, the phenomenon of quadrant power inclination is presented. It will be appreciated that this calculation process is a theoretical calculation process, i.e. corresponds to a pre-judgment process. Ultimately, it can be advantageous for the measurement data to be based on old cycles; the reactor core model for theoretical calculation is used for performing quadrant power inclination pre-judgment on a new circulation model.

In one embodiment, as shown in FIG. 2, there are 1, 2, 3, 4, four fuel assemblies, by which deformation measurements are translated into displacement of the fuel assemblies within the stack. Assuming that the initial gap width of the No. 1 component and the No. 2 component is 2mm, when the No. 1 component is deformed rightward (X+ direction) by a deformation amount of 1.4mm, and is displaced by 1mm; the component No. 2 is not deformed in the X direction, and the displacement is 0mm; the gap widths of the component No. 1 and the component No. 2 are d=2-1+0=1 (mm), and core power distribution calculation based on the new gap is finally required.

S4, obtaining an evaluation result of the reactor core power inclination state according to the reactor core power inclination data. Specifically, the evaluation result of the core power tilt state is finally obtained from the core power tilt data. In an embodiment, it may be determined whether the core power tilt data is greater than a preset value, and if the core power tilt data is less than the preset value, it is determined that the core power tilt status is reasonable, otherwise it is determined that the core power tilt status is not reasonable. That is, it is possible to determine whether the current core tilt status is within an acceptable range according to the magnitude of the core power tilt data. For example, if the current power ramp is less than 1%; the current scheme has a reasonable power ramp state and is acceptable. If the current power tilt is greater than 1%; the current scheme power ramp state is not reasonable and is not acceptable.

Optionally, in the method for evaluating a power tilt state of a quadrant of a reactor core of a reactor according to the present invention, when it is determined that the power tilt state of the reactor core is not reasonable, a power change state of the fuel assembly is obtained, so as to adjust a position of the fuel assembly according to the power change state of the fuel assembly. When the current reactor core power inclination state is not reasonable, namely the current reactor core power arrangement is not in an ideal state, the positions of the fuel assemblies can be adjusted at the moment, so that the power distribution of the reactor core is in a more ideal state. Wherein the position adjustment mode of the fuel assembly can be confirmed according to the power change state of the fuel assembly.

In an embodiment, when the power change state of the fuel assembly becomes larger, the power change state of the fuel assembly corresponding to the symmetrical position of the fuel assembly is acquired, and the fuel assembly with the smaller power level is acquired for replacement. I.e. when the power of the current fuel assembly increases at that location due to deformation, the fuel assembly at that location can be swapped with a symmetrical location fuel assembly with a smaller power level.

In an embodiment, when the power change state of the fuel assembly becomes smaller, the power change state of the fuel assembly corresponding to the symmetrical position of the fuel assembly is acquired, and the fuel assembly with the larger power level is acquired for replacement. I.e. when the power of the current fuel assembly decreases at that location due to deformation, the fuel assembly at that location can be swapped with a symmetrical location fuel assembly with a greater power level.

In one particular embodiment, as shown in FIG. 3, the core has a total of 157 fuel assemblies (one square representing one assembly); there is a gap between the fuel assemblies during actual loading. Conventional theoretical calculations do not take into account the deformations and offsets of the actual fuel assemblies in the core. I.e., the fuel assembly-to-fuel assembly spacing, is nominal (specific/fixed). As shown in fig. 4, the fuel assembly is schematically structured, and the fuel assembly is deformed in bending (from an axial view), and the deformation amount of the fuel assembly at different heights shifted to the right in the two-dimensional model is not uniform, so that when the fuel assembly is applied to the two-dimensional model, the overall average value is generally taken. If the fuel assembly is deformed, its position within the core is moved, as shown in FIG. 2, and the spacing between the fuel assemblies is changed.

For a given core loading scenario, calculating the power distribution levels of the core components thereof without changing the fuel assembly gap distribution, pa (i=1,., n), as shown in fig. 5; (where n is typically 157, i.e., 157 fuel assemblies). As shown in fig. 6, the power distribution level of each fuel assembly, pb (i=1,..n), was calculated when considering the asymmetric fuel assembly gap distribution. The calculated deviation of the two models is shown in figure 7, the Pa and Pb of the fuel assemblies are compared one by one, if Pa > Pb, the power of the position is proved to be lower, the fuel assemblies at the symmetrical position are properly exchanged, and the symmetrical fuel assemblies with high reactivity are arranged at the position; if Pa < Pb, it turns out that the power is low at this location, the fuel assemblies at the symmetrical locations should be properly swapped, and the symmetrical fuel assemblies with low reactivity placed at this location. As shown in fig. 8, the adjustment process can be to interchange the fuel assemblies at a, b, c, d four positions as needed.

In the process, the whole power inclination amplitude is combined to be properly adjusted; if there is no suitable fuel assembly to exchange, then no change is made. The reactor core loading is generally in quarter rotational symmetry, and part of the reactor core loading is in eighth rotational symmetry; the residual enrichment degree between the fuel assemblies at each symmetrical position is different due to certain non-uniformity in the burning process of the earlier cycle, and the reactivity is also different; by swapping the high reactivity and low reactivity fuel assemblies in symmetrical positions, efficient suppression of core quadrant power tilt conditions during real operation can be achieved.

In the invention, the quadrant power inclined state of the nuclear pile in the operation process can be primarily evaluated in the process of the fuel change design according to the deformation measurement data of the old fuel assembly. And the design scheme can be quantitatively adjusted and optimized according to the obtained evaluation index, so that the power tilting state is reduced. The inclination degree of the quadrants of the reactor core is reduced, and the safety of the reactor core is further ensured.

It is to be understood that the above examples only represent preferred embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention; it should be noted that, for a person skilled in the art, the above technical features can be freely combined, and several variations and modifications can be made without departing from the scope of the invention; therefore, all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (10)

1. A method for evaluating the power inclination state of a quadrant of a reactor core is characterized by comprising the following steps:

S1, acquiring position information and deformation data corresponding to each fuel assembly in a previous circulating reactor core;

s2, acquiring the displacement of the fuel assembly corresponding to the reactor core based on the deformation data of the fuel assembly;

s3, correcting a modeling model corresponding to the reactor core in the current cycle based on the displacement of the fuel assembly and the position information of the fuel assembly, so as to obtain reactor core power inclination data corresponding to the reactor in the current cycle according to the corrected modeling model;

s4, obtaining an evaluation result of the reactor core power inclination state according to the reactor core power inclination data.

2. The method for evaluating a power tilt state of a quadrant of a reactor core according to claim 1, wherein in the step S1, position information and deformation data corresponding to each fuel assembly in a previous cycle core are acquired; comprising the following steps:

and in the refueling and overhaul process of the nuclear power unit, acquiring the position information of each fuel assembly in the reactor core and the deformation data of the fuel assemblies in the previous cycle.

3. The reactor core quadrant power tilt state assessment method of claim 1, further comprising:

And acquiring the inherent deformation characteristics corresponding to each position in the reactor core, so as to acquire the deformation data of the fuel assembly in the previous cycle according to the position information of the fuel assembly in the previous cycle and the inherent deformation characteristics corresponding to the position.

4. The reactor core quadrant power ramp state evaluation method of claim 3, further comprising:

And acquiring the inherent deformation characteristic based on historical data in the overhaul process of the nuclear power unit, wherein the historical data comprises the acquired position information of each fuel assembly in the reactor core and the deformation data of the fuel assembly in the refueling overhaul process of the nuclear power unit each time.

5. The reactor core quadrant power tilt state evaluation method according to claim 1, wherein in the step S2, the displacement amount of the fuel assembly corresponding to the core is obtained based on deformation data of the fuel assembly; comprising the following steps:

and converting the deformation data of the fuel assembly based on a preset conversion function to obtain the displacement of the fuel assembly relative to a preset position.

6. The reactor core quadrant power ramp state evaluation method of claim 5, wherein the preset transfer function is: f2 =f1/K, where F1 is deformation data of the fuel assembly, F2 is displacement amount of the fuel assembly, and K is a constant.

7. The reactor core quadrant power inclination state evaluation method according to claim 1, characterized in that in the step S3, the modeling model corresponding to the core of the current cycle is corrected based on the displacement amount of the fuel assembly and the position information of the fuel assembly to obtain the reactor core power inclination data corresponding to the reactor according to the corrected modeling model; comprising the following steps:

Gaps of the fuel assemblies in the reactor core in the current cycle are reset based on the displacement amounts of the fuel assemblies and the position information of the fuel assemblies, so that modeling models corresponding to the reactor core are updated according to the new gaps, and the reactor core power inclination data are acquired.

8. The reactor core quadrant power tilt state evaluation method according to claim 1, wherein in the step S4, the obtaining the evaluation result of the core power tilt state from the core power tilt data includes:

judging whether the reactor core power inclination data is larger than a preset value, judging that the reactor core power inclination state is reasonable when the reactor core power inclination data is smaller than the preset value, and otherwise judging that the reactor core power inclination state is unreasonable.

9. The reactor core quadrant power tilt state evaluation method of claim 8, further comprising:

And when the reactor core power inclination state is judged to be unreasonable, acquiring the power change state of the fuel assembly so as to adjust the position of the fuel assembly according to the power change state of the fuel assembly.

10. The reactor core quadrant power tilt state assessment method of claim 9, further comprising:

When the power change state of the fuel assembly becomes larger, acquiring the power change state of the fuel assembly at the symmetrical position corresponding to the fuel assembly, and acquiring the fuel assembly with smaller power level for exchanging;

And when the power change state of the fuel assembly is smaller, acquiring the power change state of the fuel assembly at the symmetrical position corresponding to the fuel assembly, and acquiring the fuel assembly with larger power level for replacement.