JPH05264765A - Relaxation method of irradiation growth of nuclear fuel assembly for pwr and lower nozzle - Google Patents
Relaxation method of irradiation growth of nuclear fuel assembly for pwr and lower nozzleInfo
- Publication number
- JPH05264765A JPH05264765A JP4090103A JP9010392A JPH05264765A JP H05264765 A JPH05264765 A JP H05264765A JP 4090103 A JP4090103 A JP 4090103A JP 9010392 A JP9010392 A JP 9010392A JP H05264765 A JPH05264765 A JP H05264765A
- Authority
- JP
- Japan
- Prior art keywords
- nuclear fuel
- fuel assembly
- pwr
- lower nozzle
- plate
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
Classifications
-
- 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
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、加圧水型原子炉（ＰＷ
Ｒ）用の核燃料集合体の炉心運転に伴なう照射成長を相
殺して、ＰＷＲ用核燃料集合体の見掛けの全長をほぼ一
定に保つＰＷＲ用核燃料集合体の照射成長の緩和方法、
および該方法の実行に好適なＰＷＲ用核燃料集合体の下
部ノズルに関する。BACKGROUND OF THE INVENTION The present invention relates to a pressurized water reactor (PW).
R), a method for mitigating irradiation growth of a PWR nuclear fuel assembly by offsetting the irradiation growth associated with the core operation of the nuclear fuel assembly for keeping the apparent total length of the PWR nuclear fuel assembly substantially constant,
And a lower nozzle of a PWR nuclear fuel assembly suitable for carrying out the method.
【０００２】[0002]
【従来の技術】多数の核燃料集合体を配列させた炉心内
で、核燃料集合体に沿って未沸騰の加圧冷却水を強制的
に上昇させ、これにより核燃料集合体の熱交換（冷却除
熱）を行う加圧水型原子炉（ＰＷＲ）は、現在、沸騰水
型原子炉（ＢＷＲ）と並んで最も実用的で高実績な動力
炉である。運転中、炉心の上方から高温未沸騰水の出力
を取り出すＰＷＲの核燃料集合体（以下ＰＷＲ用核燃料
集合体）は、水蒸気出力を取り出すＢＷＲの核燃料集合
体よりも強い水流下に曝されるため、ＰＷＲ用核燃料集
合体は、浮き上がりを防止するため、上下に圧縮方向で
ばね付勢されて炉心に配列されている。この状態で炉心
運転がなされて、中性子や各種放射線の照射によってＰ
ＷＲ用核燃料集合体が照射成長を起すと、ばね付勢によ
る上下方向の圧縮力が増してＰＷＲ用核燃料集合体全体
が変形する可能性がある。ＰＷＲ用核燃料集合体が変形
すると、隣接するＰＷＲ用核燃料集合体に干渉してＰＷ
Ｒ用核燃料集合体を上方に取出すことが困難になる。ま
た、ばねに過度の荷重が働いてへたりを起し、浮き上が
り防止の作用が減じる可能性もある。2. Description of the Related Art In a core in which a large number of nuclear fuel assemblies are arranged, unboiled pressurized cooling water is forcibly raised along the nuclear fuel assemblies, whereby heat exchange (cooling heat removal) of the nuclear fuel assemblies is performed. The pressurized water nuclear reactor (PWR) which carries out (1) is currently the most practical and highly proven power reactor alongside the boiling water nuclear reactor (BWR). During operation, the PWR nuclear fuel assembly (hereinafter referred to as PWR nuclear fuel assembly) that extracts the output of high-temperature unboiled water from above the core is exposed to a stronger water flow than the BWR nuclear fuel assembly that extracts the steam output. The PWR nuclear fuel assembly is arranged in the core while being spring-biased in the up-down direction in the compression direction in order to prevent floating. In this state, core operation is performed and P is generated by irradiation with neutrons and various radiations.
When the WR nuclear fuel assembly undergoes irradiation growth, the compressive force in the vertical direction due to the spring bias increases, and the entire PWR nuclear fuel assembly may be deformed. When the PWR nuclear fuel assembly is deformed, it interferes with the adjacent PWR nuclear fuel assembly and the PW
It becomes difficult to take out the R nuclear fuel assembly upward. Further, excessive load may be applied to the spring to cause sagging, which may reduce the lifting prevention function.
【０００３】現在、ＰＷＲ用核燃料集合体では、従来よ
りも高濃縮の核燃料を用いて長時間の運転を可能にする
試みが行われており、長時間運転の条件下では、この照
射成長の問題がより深刻である。従って、この照射成長
を相殺してＰＷＲ用核燃料集合体の見掛けの全長をほぼ
一定に保ち、ＰＷＲ用核燃料集合体に座屈変形や曲り変
形を起さないようにする方法が望まれている。At present, in the nuclear fuel assembly for PWR, an attempt has been made to make it possible to operate for a long time by using a nuclear fuel having a higher concentration than before, and under the condition of a long time operation, there is a problem of this irradiation growth. Is more serious. Therefore, there is a demand for a method of canceling this irradiation growth to keep the apparent total length of the PWR nuclear fuel assembly substantially constant and prevent buckling or bending deformation of the PWR nuclear fuel assembly.
【０００４】ＰＷＲ用核燃料集合体は、例えば１７×１
７格子型の場合、上部ノズルと下部ノズルを長さ４ｍ余
りの制御棒案内管（シンブル管）２４本で一体に接続
し、制御棒案内管の中段高さに９個の支持格子を固定し
て籠体を形成し、この籠体の枠組み内に口径約９mm、長
さ約３．９ｍの燃料棒２６４本と中心に計装用案内管１
本とを格子状に配置して支持したものである。ＰＷＲ用
核燃料集合体の上下方向の荷重は、専らシンブル管２４
本で負担しており、燃料棒は、シンブル管２４本と支持
格子で構成される籠体中にこの荷重と無関係に把持され
ている。ＰＷＲ用核燃料集合体は、上部ノズルに設けた
ホ−ルドダウンスプリングがもたらす下向きの反発力に
よって、炉心の上部炉心板と下部炉心板の間に拘束され
ており、ＰＷＲの炉心内には、約２００体のＰＷＲ用核
燃料集合体が相互の間隔を詰めて格子状に配列される。
（図１参照）A nuclear fuel assembly for PWR is, for example, 17 × 1.
In the case of 7-grid type, the upper nozzle and the lower nozzle are connected integrally with 24 control rod guide tubes (thimble pipes) with a length of 4 m or more, and 9 support grids are fixed at the middle height of the control rod guide tubes. To form a basket, and inside the framework of this basket, there are 264 fuel rods with a diameter of about 9 mm and a length of about 3.9 m, and an instrumentation guide tube 1 at the center.
The book and the book are arranged and supported in a grid pattern. The vertical load of the PWR nuclear fuel assembly is limited to the thimble tube 24.
It is carried by a book, and the fuel rods are held in a cage composed of 24 thimble tubes and a supporting grid regardless of this load. The nuclear fuel assembly for PWR is constrained between the upper core plate and the lower core plate of the core by the downward repulsive force provided by the hold down spring provided in the upper nozzle, and about 200 bodies are contained in the core of the PWR. The nuclear fuel assemblies for PWRs are arranged in a grid pattern with a space between them.
(See Figure 1)
【０００５】ＰＷＲの炉心運営管理としては、燃料交換
の際に、全体の１／３の古いＰＷＲ用核燃料集合体を炉
心から取り出し、残りのＰＷＲ用核燃料集合体を古い順
で中心部に移動し、空白となった炉心の外周部に新規の
ＰＷＲ用核燃料集合体を全体の１／３補充している。こ
の際、炉心滞在時間の長いＰＷＲ用核燃料集合体ほど照
射成長量が大きく、取り出されるＰＷＲ用核燃料集合体
は新規のＰＷＲ用核燃料集合体に比較して５〜１０mmも
その全長が伸びている。For core management of the PWR, at the time of refueling, one third of the old PWR nuclear fuel assemblies are taken out of the core, and the remaining PWR nuclear fuel assemblies are moved to the center in the old order. A new PWR nuclear fuel assembly is replenished to the outer periphery of the blank core by a third. At this time, the irradiation growth amount is larger for the PWR nuclear fuel assembly having a longer core stay time, and the total length of the PWR nuclear fuel assembly to be taken out is 5 to 10 mm longer than that of the new PWR nuclear fuel assembly.
【０００６】[0006]
【発明が解決しようとする課題】ＰＷＲ用核燃料集合体
の照射成長は、炉心運転に伴なう長期間の中性子やα線
等の照射を経て、長さ４ｍ余りのシンブル管の材料であ
るジルカロイ合金の最密六方晶構造が部分的に変形し
て、そのひずみが積重なったものである。照射成長の割
合は結晶構造の方向によってばらつき、最終的な成長量
は、圧延後のシンブル管における結晶方向の分布状態、
圧延後の熱処理温度、照射された中性子のエネルギ−分
布等に左右されるため、ＰＷＲ用核燃料集合体の相互間
やシンブル管の相互間でも多少ばらついている。また、
同様にジルカロイ合金からなる燃料棒の被覆管も照射成
長を引き起こすが、燃料棒は一緒に照射成長するシンブ
ル管によって上下方向の荷重から無関係に支持されてい
るため、自身の照射成長によって燃料棒の上下方向の応
力が増すことは少ない。Irradiation growth of a nuclear fuel assembly for PWR is carried out by irradiation of neutrons, α rays, etc. for a long period of time associated with core operation, and Zircaloy, which is a material for thimble tubes having a length of about 4 m. The close-packed hexagonal structure of the alloy is partially deformed and the strain is accumulated. The irradiation growth rate varies depending on the direction of the crystal structure, and the final growth amount is the distribution state of the crystal direction in the thimble tube after rolling,
Since it depends on the heat treatment temperature after rolling, the energy distribution of the irradiated neutrons, etc., there is some variation between the PWR nuclear fuel assemblies and among the thimble tubes. Also,
Similarly, the cladding of fuel rods made of Zircaloy alloy also causes irradiation growth.However, since the fuel rods are supported by the thimble tubes that grow together with irradiation regardless of the vertical load, the irradiation growth of the fuel rods causes the fuel rods to grow. Vertical stress is unlikely to increase.
【０００７】一方、上部炉心板と下部炉心板とが固定さ
れた圧力容器は照射成長のごく少ない厚いステンレス製
であるから、上部炉心板と下部炉心板の間隔は、炉心運
転中を通じてほぼ一定不変である。従って、ＰＷＲ用核
燃料集合体の重量とホ−ルドダウンスプリングの反発力
を負担するＰＷＲ用核燃料集合体のシンブル管の照射成
長は、ホ−ルドダウンスプリングをさらに圧縮変形させ
て、その反発力を増加させ、シンブル管に作用する圧縮
荷重を高めることとなる。そして、圧縮荷重の増加に屈
したシンブル管が曲り変形を起すと、この曲りに追従し
て支持格子がＰＷＲ用核燃料集合体の側方に飛出し、隣
接するＰＷＲ用核燃料集合体に干渉したり、燃料棒に曲
り変形を誘発して、支持格子と燃料棒の支持状態が変化
して両者間に摩擦や振動を引き起こす可能性もある。ま
た、ホ−ルドダウンスプリングのへたりにより、燃料集
合体の浮き上がりが防止できない事態も生じ得る。On the other hand, since the pressure vessel to which the upper core plate and the lower core plate are fixed is made of thick stainless steel with very little irradiation growth, the distance between the upper core plate and the lower core plate remains almost constant throughout the core operation. Is. Therefore, the irradiation growth of the thimble tube of the PWR nuclear fuel assembly, which bears the weight of the PWR nuclear fuel assembly and the repulsive force of the hold down spring, causes the holddown spring to be further compressed and deformed, and its repulsive force is increased. The compressive load acting on the thimble tube is increased. Then, when the thimble tube that bends due to an increase in compressive load bends and deforms, the support grid follows the bend and pops out to the side of the PWR nuclear fuel assembly and interferes with the adjacent PWR nuclear fuel assembly. There is also a possibility that bending deformation is induced in the fuel rods, the supporting state of the support grid and the fuel rods is changed, and friction and vibration are caused between them. Further, due to the fatigue of the hold-down spring, it may not be possible to prevent the fuel assembly from rising.
【０００８】このようなＰＷＲ用核燃料集合体の照射成
長の問題を鑑みて、シンブル管の長手方向にジルカロ
イの成長の少ない結晶軸を配向させる、ＰＷＲ用核燃
料集合体の全長を照射成長の見込み分もともと短くして
おく等の対策が提案されているが、では、ジルカロイ
圧延時の結晶軸の管理がほとんど不可能で、製品検査に
も手間取り、では、ホ−ルドダウンスプリングや燃料
棒の設計を始めからやり直す必要がある。In view of the above problem of irradiation growth of the PWR nuclear fuel assembly, the total length of the PWR nuclear fuel assembly in which the crystal axis with less growth of zircaloy is oriented in the longitudinal direction of the thimble tube is the expected amount of irradiation growth. Originally, measures such as shortening have been proposed, but it is almost impossible to control the crystal axis during Zircaloy rolling, and it takes time to inspect the product. You need to start over.
【０００９】本発明は、シンブル管が照射成長した場合
でもＰＷＲ用核燃料集合体に作用する圧縮荷重を高めな
いで済む、正確には、少なくとも燃料交換の際に、照射
成長分を相殺してＰＷＲ用核燃料集合体の見掛けの全長
を一定に再調整するＰＷＲ用核燃料集合体の照射成長の
緩和方法、およびＰＷＲ用核燃料集合体の見掛けの全長
を一定に再調整でき、ホ−ルドダウンスプリングや燃料
棒の設計を変更する必要のないＰＷＲ用核燃料集合体の
照射成長の緩和方法、および該方法に用いられる下部ノ
ズルを提供することを目的としている。According to the present invention, it is not necessary to increase the compressive load acting on the PWR nuclear fuel assembly even when the thimble tube is irradiated and grown. To be precise, at least at the time of refueling, the irradiation growth portion is offset to cancel out the PWR. Method for re-adjusting the apparent total length of the nuclear fuel assemblies for PWRs to a constant value, and the apparent total length of the nuclear fuel assemblies for PWRs can be readjusted to a constant value. An object of the present invention is to provide a method for mitigating irradiation growth of a nuclear fuel assembly for PWR, which does not require a change in rod design, and a lower nozzle used in the method.
【００１０】[0010]
【課題を解決するための手段】請求項１のＰＷＲ用核燃
料集合体の照射成長の緩和方法は、炉心運転に伴なう照
射成長を相殺してＰＷＲ用核燃料集合体の見掛けの全長
をほぼ一定に保つＰＷＲ用核燃料集合体の照射成長の緩
和方法において、制御棒案内管を固定したプレ−ト部か
らプレ−ト部を支承する脚部を分離可能な下部ノズルを
ＰＷＲ用核燃料集合体に取付け、照射成長を起したＰＷ
Ｒ用核燃料集合体について、その前記下部ノズルの脚部
を短い脚部に交換してなる方法である。According to a method of mitigating irradiation growth of a PWR nuclear fuel assembly according to claim 1, the irradiation growth accompanying the core operation is offset to make the apparent total length of the PWR nuclear fuel assembly substantially constant. In the method of mitigating irradiation growth of a PWR nuclear fuel assembly, the lower nozzle capable of separating the leg supporting the plate from the plate fixed to the control rod guide tube is attached to the PWR nuclear fuel assembly. , PW with irradiation growth
In the R nuclear fuel assembly, the leg portion of the lower nozzle is replaced with a short leg portion.
【００１１】請求項２のＰＷＲ用核燃料集合体の下部ノ
ズルは、制御棒案内管を固定したプレ−ト部からプレ−
ト部を支承する脚部を分離可能なＰＷＲ用核燃料集合体
の下部ノズルにおいて、制御棒案内管を固定したプレ−
ト部に対して、プレ−ト部の周囲を囲む枠部分と、枠部
分から内側に突出してプレ−ト部を支承するせり出し部
分と、枠部分の外側面からの操作でプレ−ト部を固定お
よび分離可能な固定手段と、枠部分の４隅から下方向に
伸びた４本の脚部分と、からなる脚部を組合せたもので
ある。The lower nozzle of the PWR nuclear fuel assembly according to a second aspect of the present invention comprises a plate portion from which a control rod guide tube is fixed and which is a plate.
In the lower nozzle of the PWR nuclear fuel assembly in which the legs supporting the tongue can be separated, a pre-fixed control rod guide tube is fixed.
With respect to the plate portion, the frame portion surrounding the plate portion, the protruding portion that projects inward from the frame portion to support the plate portion, and the plate portion by operating from the outer surface of the frame portion. This is a combination of a fixing means that can be fixed and separated, and a leg portion including four leg portions extending downward from four corners of the frame portion.
【００１２】[0012]
【作用】請求項１のＰＷＲ用核燃料集合体の照射成長の
緩和方法においては、少なくとも燃料交換の際に、ＰＷ
Ｒ用核燃料集合体の全長を再計測し、照射成長を一定以
上起しているものについては、その下部ノズルの脚部を
短いものに交換して照射成長分を相殺し、これによりＰ
ＷＲ用核燃料集合体の見掛けの全長を一定に再調整す
る。According to the method for alleviating irradiation growth of a PWR nuclear fuel assembly according to claim 1, at least during the fuel exchange, the PW
The total length of the R nuclear fuel assembly was remeasured, and if the irradiation growth occurred for a certain amount or more, the leg portion of the lower nozzle was replaced with a shorter one to offset the irradiation growth amount.
Readjust the apparent total length of the WR nuclear fuel assembly.
【００１３】請求項２のＰＷＲ用核燃料集合体の下部ノ
ズルは、下部ノズルの脚部の交換を容易かつ確実にする
ものである。すなわち、下部ノズルの脚部の交換は、Ｐ
ＷＲ用核燃料集合体を炉心から引上げた状態で、枠部分
の外側面から固定手段を操作して、プレ−ト部と脚部と
を分離し、この枠部分を脚部分が短い別の脚部に交換し
て置換え、この別の脚部の枠部分の外側面から固定手段
を操作してプレ−ト部と脚部とを再度固定する。The lower nozzle of the PWR nuclear fuel assembly according to the second aspect of the present invention facilitates and surely replaces the leg portion of the lower nozzle. That is, the leg of the lower nozzle is replaced by P
With the WR nuclear fuel assembly pulled up from the core, the fixing means is operated from the outer surface of the frame part to separate the plate part and the leg part, and this frame part is another leg part having a short leg part. The plate portion and the leg portion are fixed again by operating the fixing means from the outer surface of the frame portion of the other leg portion.
【００１４】炉心に戻されて下部炉心板上に載置された
ＰＷＲ用核燃料集合体では、プレ−ト部にかかるシンブ
ル管からの荷重は、せり出し部分を介して４本の脚部分
に分配され、この荷重が固定手段に作用することはな
い。In the PWR nuclear fuel assembly which has been returned to the core and placed on the lower core plate, the load from the thimble tube applied to the plate portion is distributed to the four leg portions through the protruding portions. , This load does not act on the fixing means.
【００１５】[0015]
【発明の実施例】本発明の実施例を図面を参照して説明
する。Embodiments of the present invention will be described with reference to the drawings.
【００１６】図１は加圧水型原子炉（ＰＷＲ）用核燃料
集合体の説明図、図２は実施例の下部ノズルの模式図で
ある。図２は図１のＰＷＲ用核燃料集合体の下部ノズル
部分を拡大して、一部断面図示したものである。FIG. 1 is an explanatory view of a nuclear fuel assembly for a pressurized water reactor (PWR), and FIG. 2 is a schematic view of a lower nozzle of an embodiment. FIG. 2 is an enlarged partial cross-sectional view of a lower nozzle portion of the PWR nuclear fuel assembly of FIG.
【００１７】図１において、外側の図示しない圧力容器
に固定された上部炉心板Ｉと下部炉心板Ｊの間には、数
２００体のＰＷＲ用核燃料集合体Ｒ（ただし、ここでは
２体のみを示して他は省略）が相互の間隔を詰めて格子
状に配置されている。In FIG. 1, between the upper core plate I and the lower core plate J, which are fixed to a pressure vessel (not shown) on the outside, several hundreds of PWR nuclear fuel assemblies R (here, only two are included). (Others are omitted in the drawing) are arranged in a grid pattern with a narrow space between them.
【００１８】ＰＷＲ用核燃料集合体Ｒは、上部ノズルＭ
と下部ノズルＮを２４本の制御棒案内管（シンブル管
Ａ）で一体に接続し、シンブル管Ａの中段高さに９個の
支持格子Ｃを固定して籠体を形成し、この籠体の枠組み
内に多数の燃料棒Ｂを格子状に配置して支持したもので
ある。ＰＷＲ用核燃料集合体Ｒは、上部ノズルＭに設け
たホ−ルドダウンスプリングＳ１がもたらす下向きの反
発力によって、上部炉心板Ｉと下部炉心板Ｊの間隔に拘
束されており、ホ−ルドダウンスプリングＳ１が作用す
るＰＷＲ用核燃料集合体Ｒを上下方向に圧縮する荷重は
専らシンブル管Ａが負担しており、シンブル管Ａと支持
格子Ｃで構成される籠体中に把持された燃料棒Ｂに、こ
の荷重は直接には作用していない。The nuclear fuel assembly R for PWR has an upper nozzle M.
The lower nozzle N and the lower nozzle N are integrally connected with 24 control rod guide tubes (thimble tubes A), and nine support grids C are fixed to the middle height of the thimble tubes A to form a cage. A large number of fuel rods B are arranged and supported in a lattice shape within the framework of FIG. The nuclear fuel assembly R for PWR is constrained in the space between the upper core plate I and the lower core plate J by the downward repulsive force provided by the hold down spring S1 provided in the upper nozzle M. The thimble tube A exclusively bears the load for vertically compressing the PWR nuclear fuel assembly R on which the S1 acts, and the fuel rod B held in the cage composed of the thimble tube A and the support grid C , This load is not acting directly.
【００１９】このように構成されたＰＷＲ用核燃料集合
体Ｒは、運転中、炉心の上方から高温未沸騰水の出力を
取り出すときＰＷＲ用核燃料集合体Ｒに沿って上方に向
う強い水流に曝されるが、ホ−ルドダウンスプリングＳ
１によって上下方向に拘束されているため位置ずれや振
動は起さない。一方、運転期間中、中性子や各種放射線
の照射によって、ジルカロイ合金からなるシンブル管Ａ
は照射成長を起してＰＷＲ用核燃料集合体Ｒの全長（高
さ）を増加させる。これにより、ホ−ルドダウンスプリ
ングＳ１の変形量が増して、シンブル管Ａに作用する上
下方向の圧縮力が高まり、シンブル管Ａに曲げ変形また
は座屈変形を発生させる可能性がある。During operation, the PWR nuclear fuel assembly R thus constructed is exposed to a strong upward flow of water along the PWR nuclear fuel assembly R when the output of high temperature unboiled water is taken out from above the core. Hold down spring S
Since it is constrained in the vertical direction by 1, there is no displacement or vibration. On the other hand, during operation, the thimble tube A made of Zircaloy alloy is irradiated with neutrons and various radiations.
Causes irradiation growth to increase the total length (height) of the PWR nuclear fuel assembly R. As a result, the deformation amount of the hold-down spring S1 increases, and the vertical compressive force acting on the thimble tube A increases, which may cause bending or buckling deformation of the thimble tube A.
【００２０】図２において、下部ノズルＮはプレ−ト部
Ｐと脚部Ｋに分離可能である。プレ−ト部Ｐには、シン
ブル管Ａを固定するための貫通孔（図示せず）と、運転
中の冷却水の貫通孔Ｈとが格子状に規則正しく多数形成
されており、シンブル管Ａは前述の貫通孔に挿入されて
固定されている。一方、脚部Ｋは、プレ−ト部Ｐの周囲
を囲む枠部分Ｅと、枠部分Ｅから内側に突出してプレ−
ト部Ｐを支承するせり出し部分Ｇと、枠部分Ｅの４隅か
ら下方向に伸ばして一体に形成した４本の脚部分Ｆとを
有する。このプレ−ト部Ｐと脚部Ｋとは、枠部分Ｅの外
側面から締結および解除可能なねじＤにより固定されて
いる。プレ−ト部Ｐにかかるシンブル管Ａからの荷重
は、せり出し部分Ｇを介して４本の脚部分Ｆに分配され
てねじＤには直接作用しないから、ねじＤの強度は、Ｐ
ＷＲ用核燃料集合体Ｒを上方から吊り下げた際にプレ−
ト部Ｐから脚部Ｋが脱落しない程度でよい。In FIG. 2, the lower nozzle N can be separated into a plate portion P and a leg portion K. In the plate portion P, a large number of through holes (not shown) for fixing the thimble tube A and through holes H of the cooling water during operation are regularly formed in a grid pattern. It is inserted and fixed in the aforementioned through hole. On the other hand, the leg portion K projects from the frame portion E to the inside by a frame portion E that surrounds the periphery of the plate portion P.
It has a protruding portion G for supporting the toe portion P and four leg portions F which are integrally formed by extending downward from four corners of the frame portion E. The plate portion P and the leg portion K are fixed to each other by a screw D that can be fastened and released from the outer surface of the frame portion E. The load applied from the thimble tube A to the plate portion P is distributed to the four leg portions F through the protruding portion G and does not directly act on the screw D, so that the strength of the screw D is P
When the WR nuclear fuel assembly R is suspended from above,
It is sufficient that the leg K does not fall off from the toe P.
【００２１】このように構成された下部ノズルＮを用い
て、燃料交換の際には、図１の上部炉心板Ｉを取除い
て、全体の１／３の古いＰＷＲ用核燃料集合体Ｒを上方
に吊り上げて炉心から取り出し、残りのＰＷＲ用核燃料
集合体Ｒを上方に吊り上げて古い順で中心部に移動して
配置替えし、空白となった炉心の外周部に新規のＰＷＲ
用核燃料集合体Ｒを全体の１／３補充する。このとき、
配置替えされるＰＷＲ用核燃料集合体Ｒについて、上方
に吊り上げた状態でその全長を再測定し、その照射成長
の程度に応じて下部ノズルＮの脚部Ｋを交換する。交換
用の脚部Ｋとしては、その高さが元の−５mm、−１０mm
である２段階２種類のものを用いる。上方に吊り上げた
ＰＷＲ用核燃料集合体Ｒに対して遠隔操作のロボットア
−ムを用いて下部ノズルＮの側方からねじＤを解除して
脚部Ｋを交換し、再度ねじＤを締結し直す。なお、これ
ら一連の作業はすべて水中で行われる。When the fuel is exchanged by using the lower nozzle N constructed as described above, the upper core plate I of FIG. 1 is removed and 1/3 of the whole old PWR nuclear fuel assembly R is moved upward. The remaining PWR nuclear fuel assembly R is lifted up and moved to the center part in the old order and rearranged, and a new PWR is attached to the outer periphery of the empty core.
1/3 of the whole nuclear fuel assembly R is replenished. At this time,
With respect to the PWR nuclear fuel assembly R to be rearranged, the entire length is remeasured in a state of being lifted upward, and the leg K of the lower nozzle N is exchanged according to the degree of irradiation growth. The height of the replacement leg K is originally -5 mm and -10 mm.
The following two types of two types are used. Using a remote-controlled robot arm for the PWR nuclear fuel assembly R lifted upward, the screw D is released from the side of the lower nozzle N, the leg K is replaced, and the screw D is refastened. .. In addition, all of these series of operations are performed in water.
【００２２】図３は、別の実施例の下部ノズルの説明図
である。ここで、(a) 、(b) はいずれも図２の実施例の
せり出し部分の変形例であって、せり出し部分を含む下
部ノズルの左肩部分の断面が示される。FIG. 3 is an explanatory view of the lower nozzle of another embodiment. Here, both (a) and (b) are modifications of the protruding portion of the embodiment of FIG. 2, and a cross section of the left shoulder portion of the lower nozzle including the protruding portion is shown.
【００２３】図３(a) において、下部ノズルＮ２はプレ
−ト部Ｐ２と脚部Ｋ２に分離可能である。脚部Ｋ２は、
プレ−ト部Ｐ２の周囲を囲む階段状の枠部分Ｅ２と、枠
部分Ｅ２から内側に突出してプレ−ト部Ｐを支承する階
段面Ｇ２とを有する。プレ−ト部Ｐ２と脚部Ｋ２とは、
枠部分Ｅ２の外側面から締結および解除可能な図示しな
い手段により固定されている。In FIG. 3A, the lower nozzle N2 can be separated into a plate portion P2 and a leg portion K2. The leg K2 is
It has a stepped frame portion E2 that surrounds the periphery of the plate portion P2, and a step surface G2 that projects inward from the frame portion E2 and supports the plate portion P. The plate portion P2 and the leg portion K2 are
It is fixed by means (not shown) that can be fastened and released from the outer surface of the frame portion E2.
【００２４】図３(b) において、下部ノズルＮ３はプレ
−ト部Ｐ３と脚部Ｋ３に分離可能である。脚部Ｋ３は、
プレ−ト部Ｐ３の周囲を囲む枠部分Ｅ３と、枠部分Ｅ３
から内側に突出してプレ−ト部Ｐを支承する斜面Ｇ３と
を有する。プレ−ト部Ｐ３と脚部Ｋ３とは、枠部分Ｅ３
の外側面から締結および解除可能な図示しない手段によ
り固定されている。In FIG. 3 (b), the lower nozzle N3 can be separated into a plate portion P3 and a leg portion K3. The leg K3 is
A frame portion E3 surrounding the plate portion P3 and a frame portion E3
And an inclined surface G3 that projects inward from and supports the plate portion P. The plate portion P3 and the leg portion K3 form a frame portion E3.
It is fixed by means (not shown) that can be fastened and released from the outer surface of the.
【００２５】[0025]
【発明の効果】請求項１のＰＷＲ用核燃料集合体の照射
成長の緩和方法によれば、少なくとも燃料交換の際にＰ
ＷＲ用核燃料集合体の見掛けの全長を再調整して、ＰＷ
Ｒ用核燃料集合体の照射成長を相殺して、ホ−ルドダウ
ンスプリングによる上下方向の圧縮力を減少できるか
ら、高濃縮の核燃料を用いて長時間の運転をさせる場合
でも、ＰＷＲ用核燃料集合体に座屈変形や曲り変形を起
さないで済み、また、ホ−ルドダウンスプリングのへた
りを防止できる。According to the method of relaxing the irradiation growth of the PWR nuclear fuel assembly according to the first aspect of the present invention, at least during the fuel exchange, the P
Readjust the apparent total length of the nuclear fuel assembly for WR
Since the irradiation growth of the R nuclear fuel assembly can be canceled out and the vertical compressive force by the hold down spring can be reduced, even when operating for a long time with the highly concentrated nuclear fuel, the PWR nuclear fuel assembly The buckling deformation and the bending deformation do not occur, and the holddown spring can be prevented from settling.
【００２６】請求項２のＰＷＲ用核燃料集合体の下部ノ
ズルによれば、下部ノズルの側方から固定手段を操作で
きるから、ＰＷＲ用核燃料集合体を上方に吊り下げた状
態で脚部を交換する作業に都合が良い。また、プレ−ト
部にかかるシンブル管からの荷重が固定手段に作用しな
いで済むから、固定手段が簡単な最小限のものでよく、
せり出し部分とプレ−ト部が接触していればＰＷＲ用核
燃料集合体の全長に誤差を生じる心配がない。According to the lower nozzle of the PWR nuclear fuel assembly of claim 2, since the fixing means can be operated from the side of the lower nozzle, the legs are exchanged while the PWR nuclear fuel assembly is suspended upward. It is convenient for work. Further, since the load from the thimble tube applied to the plate portion does not have to act on the fixing means, the fixing means may be simple and minimal,
If the protruding portion and the plate portion are in contact with each other, there is no risk of causing an error in the total length of the PWR nuclear fuel assembly.
【図１】ＰＷＲ用核燃料集合体の説明図である。FIG. 1 is an explanatory diagram of a nuclear fuel assembly for PWR.
【図２】実施例の下部ノズルの模式図である。FIG. 2 is a schematic diagram of a lower nozzle according to an embodiment.
【図３】別の実施例の下部ノズルの説明図である。FIG. 3 is an explanatory diagram of a lower nozzle according to another embodiment.
Ａ シンブル管 Ｂ 燃料棒 Ｃ 支持格子 Ｄ ねじ Ｅ 枠部分 Ｆ 脚部分 Ｈ 貫通孔 Ｇ せり出し部分 Ｋ 脚部 Ｉ 上部炉心板 Ｊ 下部炉心板 Ｍ 上部ノズル Ｎ 下部ノズル Ｐ プレ−ト部 Ｓ１ ホ−ルドダウンスプリング A thimble tube B fuel rod C support lattice D screw E frame part F leg part H through hole G protruding part K leg part I upper core plate J lower core plate M upper nozzle N lower nozzle P plate part S1 hold down spring
Claims (2)
ＷＲ用核燃料集合体の見掛けの全長をほぼ一定に保つＰ
ＷＲ用核燃料集合体の照射成長の緩和方法において、制
御棒案内管を固定したプレ−ト部からプレ−ト部を支承
する脚部を分離可能な下部ノズルをＰＷＲ用核燃料集合
体に取付け、照射成長を起したＰＷＲ用核燃料集合体に
ついて、その前記下部ノズルの脚部を短い脚部に交換し
てなることを特徴とするＰＷＲ用核燃料集合体の照射成
長の緩和方法。1. The irradiation growth caused by the core operation is canceled out to obtain P.
Keeping the apparent total length of WR nuclear fuel assemblies almost constant P
In a method of mitigating irradiation growth of a WR nuclear fuel assembly, a lower nozzle capable of separating a leg supporting the plate from a plate fixed to a control rod guide tube is attached to the PWR nuclear fuel assembly, and irradiation is performed. A method of mitigating irradiation growth of a PWR nuclear fuel assembly, characterized in that the leg portion of the lower nozzle of the grown PWR nuclear fuel assembly is replaced with a short leg portion.
プレ−ト部を支承する脚部を分離可能なＰＷＲ用核燃料
集合体の下部ノズルにおいて、制御棒案内管を固定した
プレ−ト部に対して、プレ−ト部の周囲を囲む枠部分
と、枠部分から内側に突出してプレ−ト部を支承するせ
り出し部分と、枠部分の外側面からの操作でプレ−ト部
を固定および分離可能な固定手段と、枠部分の４隅から
下方向に伸びた４本の脚部分と、からなる脚部を組合せ
たことを特徴とするＰＷＲ用核燃料集合体の下部ノズ
ル。2. A plate having a control rod guide tube fixed in a lower nozzle of a PWR nuclear fuel assembly in which a leg supporting the plate portion can be separated from a plate portion fixing the control rod guide tube. The frame part surrounding the plate part, the protruding part that projects inward from the frame part to support the plate part, and the plate part is fixed by an operation from the outer surface of the frame part. A lower nozzle of a nuclear fuel assembly for a PWR, characterized in that a leg portion including a separable fixing means and four leg portions extending downward from four corners of the frame portion is combined.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4090103A JPH05264765A (en) | 1992-03-17 | 1992-03-17 | Relaxation method of irradiation growth of nuclear fuel assembly for pwr and lower nozzle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4090103A JPH05264765A (en) | 1992-03-17 | 1992-03-17 | Relaxation method of irradiation growth of nuclear fuel assembly for pwr and lower nozzle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05264765A true JPH05264765A (en) | 1993-10-12 |
Family
ID=13989188
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4090103A Withdrawn JPH05264765A (en) | 1992-03-17 | 1992-03-17 | Relaxation method of irradiation growth of nuclear fuel assembly for pwr and lower nozzle |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05264765A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7131717B2 (en) | 1998-06-09 | 2006-11-07 | Silverbrook Research Pty Ltd | Printhead integrated circuit having ink ejecting thermal actuators |
-
1992
- 1992-03-17 JP JP4090103A patent/JPH05264765A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7131717B2 (en) | 1998-06-09 | 2006-11-07 | Silverbrook Research Pty Ltd | Printhead integrated circuit having ink ejecting thermal actuators |
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| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19990518 |