JPS59116085A - Nuclear fuel assembly - Google Patents

Abstract

(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

【発明の詳細な説明】 本発明は、原子炉燃料集合体、特に燃料集合体の横方向
強度を大きく維持すると共に、冷却材流動中の燃料棒の
振動を抑制し、構造上の健全性を確保した原子炉燃料集
合体に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention maintains high lateral strength of nuclear fuel assemblies, particularly fuel assemblies, suppresses vibration of fuel rods during coolant flow, and improves structural integrity. Concerning the secured reactor fuel assemblies.

原子炉炉心中では、燃料棒は軸方向の一次冷却水の乱流
流動による振動や、冷却水の横方向流れ、特に最近、加
圧木型原子炉の幾つかで問題となつている炉心バッフル
板つなぎ目間隙から吹き込むいわゆるバッフル流による
振動を誘起され、この撮動の大きさがある限界値を超え
ると、燃料棒の７レツテイング破損等の損傷の原因とな
る。そこで、これを防ぐ１つの有効な方法として燃料棒
を支持格子で強固に固定し、燃料棒の固有振動数を上げ
、上記振動の限界値に至らないようにすることが考えら
れるが、一方、このように燃料棒を支持格子で強固に支
持した場合には、燃料棒の曲かりを誘発し易い欠点があ
る。即ち、支持格子は従来、制ｉ、ｌｔｌ俸案内管等の
核燃料を内部に含１ない構造部材に固定されていたが、
燃料棒と構造部材との熱膨張による伸びや、中性子照射
による成長に起因した伸びに差があシ、高温運転中、燃
料棒が支持格子に対して相対的に軸方向に滑動する必要
がある。そのため、上述の如く燃料棒を支持格子で横方
向に強固に支持することは、摩擦力を増大し、燃料棒に
過大な軸方向圧縮力を付加させることがら燃料棒の曲が
りを発生させる一要因となる。In the reactor core, the fuel rods are exposed to vibrations caused by the turbulent flow of the primary cooling water in the axial direction, the lateral flow of the cooling water, and the core baffles, which have recently become a problem in some pressurized wooden reactors. Vibrations are induced by the so-called baffle flow that blows in from the gap between the plates, and if the magnitude of this vibration exceeds a certain limit, it can cause damage such as 7 retting breakage of the fuel rods. Therefore, one effective method to prevent this is to firmly fix the fuel rods with support grids to increase the natural frequency of the fuel rods so that the vibration does not reach the above-mentioned limit value. When the fuel rods are strongly supported by the support grid in this way, there is a drawback that the fuel rods are easily bent. That is, the support grid has conventionally been fixed to a structural member that does not contain nuclear fuel, such as a control pipe or an LTL guide pipe.
There is a difference in elongation between fuel rods and structural members due to thermal expansion and growth due to neutron irradiation, and during high-temperature operation, fuel rods must slide axially relative to the support grid. . Therefore, strongly supporting the fuel rods in the lateral direction with support grids as described above increases frictional force and applies excessive axial compressive force to the fuel rods, which is one of the causes of fuel rod bending. becomes.

このように支持格子を核***性物質を含まない構造部材
に固定した構造では、燃料棒を剛に支持しようとしても
燃料俸曲が９の問題から自ら限界があった。In this structure in which the support grid is fixed to a structural member that does not contain fissile material, even if the fuel rods are to be rigidly supported, there is a limit due to the problem of fuel curvature.

そこで、これらに対処し、燃料棒の伸びと共に支持格子
が構造部材を滑動し得る燃料集合体構造や、複数の支持
格子のうち、中央の支持格子のみを構造部材に固定し、
燃料棒の伸びを上下均等に吸収する構造などがさきに提
案された。Therefore, in order to deal with these problems, we developed a fuel assembly structure in which the support grid can slide on the structural member as the fuel rods elongate, and a fuel assembly structure in which only the central support grid among the plurality of support grids is fixed to the structural member.
A structure that would absorb the elongation of the fuel rods evenly on the top and bottom was proposed earlier.

しかしなから、これらの構造に関しても、なお次のよう
な欠点が認められた。即ち、 （１）　　支持部材と構造部材の接触が支持格子帯板の
ばねによっているため、支持格子横方向の荷重が作用し
たときの構造部材による支持が弱い。この結果、集合体
全体の横方向荷重に対する構造強度が小さくなる。勿論
、これは、構造部材に係合するばねの荷重を犬きくする
ことにより回避されるが、このようにすることは支持格
子の自由な摺動を阻害し、目的に反し好ましくない。However, the following drawbacks were still found in these structures. That is, (1) Since the support member and the structural member are in contact with each other by the springs of the support grid strips, the support by the structural member is weak when a load in the lateral direction of the support grid is applied. As a result, the structural strength of the entire assembly against lateral loads is reduced. Of course, this could be avoided by increasing the loading of the springs that engage the structural members, but this would impede the free sliding of the support grid and would be undesirable.

（２）支持格子による燃料棒及び構造部材の保持は本質
的に同一であり、支持格子が燃料棒の坤びと共に構造部
材に対して相対的に摺動するのは両者の本数の近いに由
来する合計摩擦力の差のみによる。従って、依然小さく
なったとは云え、燃料棒に対する軸方向圧縮荷重が作用
し、燃料棒曲がりに対する悪影響は完全に防止できる訳
ではない。(2) The holding of fuel rods and structural members by the support grid is essentially the same, and the reason why the support grid slides relative to the structural member as the fuel rods move is due to the close number of both rods. due only to the difference in the total frictional force. Therefore, although the load is still reduced, the axial compressive load acts on the fuel rods, and the adverse effects on fuel rod bending cannot be completely prevented.

（３）原子炉内で燃料を使用する場合、高温かつ中性子
照射を受ける環境の下で支持格子ばねは応力緩和現象を
起し、ばね力は減少する。燃料棒及び構造部材に接触す
るばねを比較すると、発熱体である燃料棒に近いばねの
方が僅かに温度が尚く、また応力緩和現象に効果を及ぼ
す高速中性子の照射量の大きい燃料近傍のばねの方が応
力緩和量は大きくなる。(3) When using fuel in a nuclear reactor, the support lattice spring undergoes stress relaxation phenomenon under high temperature and neutron irradiation environment, and the spring force decreases. When comparing the springs that come into contact with fuel rods and structural members, we find that the springs that are closer to the fuel rod, which is the heating element, are slightly warmer, and the springs that are closer to the fuel rod, which is the heating element, are slightly warmer. A spring has a larger amount of stress relaxation.

一方、普通の燃料棒膜用では高圧の一次冷却材に対して
燃料棒内圧は寿命末期まで小さくなるように設計される
。従って、燃料棒被覆管は、この内外圧の差及び上記の
高温、中性子照射条件下で少くとも通常の核燃料体であ
るＵＯ２、ＰｕＯ２、Ｔｈ０２あるいはこれらの混合物
のペレットのスウェリングにより内面から支持されるよ
うになる燃料寿命中期までの間は外径か小さくなるよう
なりリープ変形をする。そして燃料棒の外径の減少は支
持格子帯板のばねの変位量を小さくし、その結果、燃料
棒に対する支持格子の保持力は減少する。従って、これ
らの効果が複合され、燃料便用中には、前記（２）で述
べた欠点は増幅され、必らずしも初期の目的通りの効果
が寿られないという事態を呈していた。On the other hand, for ordinary fuel rod membranes, the internal pressure of the fuel rod is designed to be low until the end of its life compared to the high-pressure primary coolant. Therefore, the fuel rod cladding tube is supported from the inside by the swelling of pellets of UO2, PuO2, Th02, or a mixture thereof, which are normal nuclear fuel bodies, under this difference in internal and external pressures and the above-mentioned high temperature and neutron irradiation conditions. Until the middle of the fuel's life, when the fuel's outer diameter becomes smaller, it undergoes a leap deformation. The reduction in the outer diameter of the fuel rods reduces the amount of spring displacement of the support grid strips, and as a result, the holding force of the support grid against the fuel rods decreases. Therefore, these effects are compounded, and the disadvantages mentioned in (2) above are amplified during fuel use, resulting in a situation where the initial intended effect is not necessarily maintained.

なお、云う迄もないが、ばね力の減少は、当初の設計段
階で充分に考慮され、ばね力減少後でも所定のばね力か
維持されるよう、燃料製造時には予め、太き目の値に設
定されるものであるから減少した結果、燃料棒曲がりに
関連する軸方向摩擦抵抗圧縮力が低減され、燃料棒挙動
の上で好ましい変化であるとは云えない。Needless to say, the reduction in spring force was fully taken into consideration at the initial design stage, and a thicker value was set in advance during fuel production to ensure that the specified spring force was maintained even after the spring force was reduced. As a result, the axial frictional resistance compressive force associated with fuel rod bending is reduced, which cannot be said to be a favorable change in fuel rod behavior.

（４）原子炉の事故を評価する場合、例えば−次冷却水
の出口部配管破断のような事故状態を考１鼠する必要か
あシ、燃料集合体に通常の冷却材流動による」二向きの
力よりも遥かに大きな流水力学的な上向き荷重が作用し
ても、構造」二の大破損につながらないような配慮が必
要である。ところが、前記燃料棒の伸びと共に支持格子
が構造部材を滑動し得る集合体構造の場合には、実質的
に燃料棒及び支持格子で構成される燃料棒ノ・ンドルの
上方への浮き上り及び過渡的な冷却材の激しい流出か終
了した後の落下は防止で４きす大破損につながる可能性
がある。(4) When evaluating a nuclear reactor accident, it is necessary to consider accident conditions such as a rupture of the secondary cooling water outlet pipe, for example, due to the normal flow of coolant into the fuel assembly. Care must be taken to ensure that even if a hydraulic upward load, which is much greater than the force of However, in the case of an aggregate structure in which the support grid can slide on a structural member as the fuel rods elongate, the fuel rod nozzle, which is substantially composed of the fuel rods and the support grid, rises upward and transient A violent outflow of the coolant or a fall after it has finished may lead to serious damage.

また、後者の中央の支持格子のみ全構造部材に固定した
例では、」二記（２）　（３）で示された理由によ゛り
構造部材に固定された支持格子のばね力は小さくなり、
通常、ひとつの支持格子の薄肉帯板で形成されるばねで
は、到底、過渡的な大きな上方への荷重は支え切れない
。固定支持格子が実質的に中性子照射量、即ち出力が最
大となるような軸方向中心部に配置されることを考えれ
ば、なお史、この欠点は明らかとなる。In addition, in the latter example where only the central support grid is fixed to all structural members, the spring force of the support grid fixed to the structural members becomes smaller due to the reasons shown in 2.(2) and (3). ,
Normally, a spring formed from a thin strip of a single support grid cannot support a large transient upward load. This shortcoming becomes even more apparent when one considers that the fixed support grid is located at the axial center where the neutron dose, ie the power, is substantially the greatest.

本発明は叙上の如き実状と、従来における上記欠点に着
目し、それら欠点を解消して燃Ｆ４棒を支持格子によっ
て強く保持し得て燃料棒の振動を抑制することができ、
しかも集合体の横方向強度をも大ならしめ、かつ燃料寿
命中の全期間にわたって冷却材喪失事故などの場合に燃
料棒ハンドルに加わる上向き荷重に対して燃料棒を軸方
向所定位置に充分保持することができる構造上、健全性
をもつ燃料集合体を提供することを目的とするものであ
る。The present invention focuses on the above-mentioned actual situation and the above-mentioned drawbacks of the conventional technology, and eliminates these drawbacks so that the fuel F4 rods can be strongly held by the support grid and the vibrations of the fuel rods can be suppressed.
It also increases the lateral strength of the assembly and sufficiently holds the fuel rods in place axially against upward loads applied to the fuel rod handles in the event of a loss of coolant accident or the like throughout the fuel life. The objective is to provide a fuel assembly that is structurally sound.

即ち、本発明の特徴とするところは、燃料集合体の支持
格子において特に制御棒案内管等の構造部材が挿通され
るセルを構成する４つの壁面となる支持格子帯板部分に
剛な、前記構造部材に対する受は座を形成し、該受は座
を支持格子セル内で構造部ｖＪを間欠的に受は止める円
周状輪郭となし、その内径を前記構造部材の外径と略同
−又は僅かに大きくなるように設定すると共に、燃料棒
及び構造部材を長さ方向に支持する複数個の支持格子の
うち、燃料有効長の軸方向外方に位置する支持格子の少
なくとも１個を前記構造部材に関連して、あるいは独立
に他の結合部材を介して燃料集合体の全体構造を軸方向
で区画する上部又は下部端板に対し固定せしめた点にあ
る。That is, the present invention is characterized in that, in the support grid of the fuel assembly, in particular, the support grid band plate portions forming the four wall surfaces forming the cells through which structural members such as control rod guide tubes are inserted are provided with a rigid structure. The bearing for the structural member forms a seat, the bearing having a circumferential contour to intermittently catch the structural part vJ in the support grid cells, the inner diameter of which is approximately the same as the outer diameter of said structural member. or slightly larger, and at least one of the support grids located outside the fuel effective length in the axial direction among the plurality of support grids that support the fuel rod and the structural member in the longitudinal direction is The point is that it is fixed to an upper or lower end plate that axially partitions the overall structure of the fuel assembly, either in conjunction with the structural member or independently via other connecting members.

以下、これを詳述すると、制御棒案内管等の核***性物
質を含まない構造部材を挿通する支持格子セルを構成す
る帯状部分の前記受は座は、構造強度の大なる、所謂、
「剛な」受は座であり、セルの４つの壁面に配置された
番受は座によってその内面に構造部材を間欠的に保持す
る仮想円形状の輪郭を形成しており、この輪郭の内径は
構造部材の外径と略等しいか僅かに大きく設定されなけ
ればならない。To explain this in detail below, the receiving seat of the band-shaped portion that constitutes the support grid cell through which a structural member that does not contain fissile material such as a control rod guide tube is inserted has a high structural strength.
The "rigid" supports are seats, and the seats are located on the four walls of the cell, forming an imaginary circular profile that intermittently holds structural members on its inner surface, and the inner diameter of this profile is must be approximately equal to or slightly larger than the outer diameter of the structural member.

そして、この受は座はこれによって構造部材と、支持格
子の軸方向の自由な摺動を保障すると共に横方向の相対
移動を剛な関係で抑制する。The support and seat thereby ensure free sliding movement in the axial direction of the structural member and the support grid, and also suppress relative movement in the lateral direction in a rigid relationship.

かくして、燃料棒を強い保持力で支持する支持格子は構
造部材に対して自由に摺動することが可能となり、燃料
棒と構造部材との伸びの差に起因する燃料棒軸方向圧縮
荷重を完全に排除できると共に、集合体の柚方向荷重に
対する構造強度を大ならしめる。In this way, the support grid that supports the fuel rods with a strong holding force can slide freely relative to the structural members, completely absorbing the compressive load in the axial direction of the fuel rods caused by the difference in elongation between the fuel rods and the structural members. In addition, it increases the structural strength of the assembly against loads in the vertical direction.

なお、上記の場合、構造部材と支持部材の材質を加味し
、支持格子の方が構造部材に比し、熱膨張重大となるよ
う選定することによってより一層、軸方向に自由な摺動
を保持する機能が達成される。In the above case, by taking into account the materials of the structural members and supporting members, and selecting the support grid so that thermal expansion is more significant than that of the structural members, more free sliding in the axial direction can be maintained. functions are achieved.

そのため、制御棒案内管の材質にステンレス鋼又は商品
名：インコネルと呼ばれるニッケル基合金を用いること
は極めて好適である。Therefore, it is extremely suitable to use stainless steel or a nickel-based alloy called Inconel as the material for the control rod guide tube.

しかも、本発明では、更に前記の通り燃料有効長の軸方
向外方に位置する支持格子のうち、少くとも１個は、こ
れを制御棒案内管等の構造部材に直接関連し、又は独立
に他の任意結合部側を介して燃料集合体の全体構造を区
画する上部９１Ｍ板又は下部端板に対して固定すること
が要求される。Moreover, in the present invention, as described above, at least one of the support grids located axially outward of the effective length of the fuel is connected directly to a structural member such as a control rod guide tube or independently. It is required to be fixed to the upper 91M plate or the lower end plate that partitions the overall structure of the fuel assembly via other optional joints.

これは、冷却材喪失事故等の場合の燃料棒あるいは燃料
棒ハンドルに作用する過渡的な大きな軸方向上向き荷重
に対して安全に燃料棒を所定位置に保持し構造上の健全
性を確保する役割を有する。This serves to safely hold the fuel rods in place and ensure structural integrity against transient large axial upward loads acting on the fuel rods or fuel rod handles in the event of a loss of coolant accident, etc. has.

ここで燃料有効長部分方の支持格子を選んで固定させた
のは、支持格子の前記ばねの応力緩和現象の殆んどの部
分が、高速中性子の照射による事実に鑑みて高速中性子
束が急激に減少する燃料有効長部分が好適であるとの理
由による。Here, the support grid on the side of the effective length of the fuel was selected and fixed in view of the fact that most of the stress relaxation phenomenon in the spring of the support grid is due to fast neutron irradiation. This is because a decreasing fuel effective length portion is preferred.

なかでも、特に冷却材喪失事故等の場合の構造上の健全
性をより大きな余裕をもって達成する目的からは、燃料
有効長外方に位置する最上部及び最下部の支持格子の何
れか一方に限らず、その両者を共に固定するのが望まし
い。しかし、その他の事由を考慮すれば、それら両者の
何れか一方のみでも充分である。In particular, for the purpose of achieving structural integrity with a greater margin in the event of a loss of coolant accident, etc., it is necessary to limit support grids to either the top or bottom support grid located outside the effective fuel length. First, it is desirable to fix both together. However, if other reasons are taken into account, either one of them is sufficient.

最上部、最下部の副支持格子を共に固定するときは、副
支持格子を燃料棒か摺動する必要が生じ、その結果、燃
料棒に軸方向圧縮荷重が伺勢されるけれども、例えば従
来の加圧水型原子炉燃料集合体では７〜９個の支持格子
の各々から同様の圧縮荷重を加えられた点を考慮すれば
荷電の大きさは数分の−に減じ、充分、本発明における
目的は達成される。When fixing the top and bottom sub-support grids together, it is necessary to slide the sub-support grids against the fuel rods, and as a result, an axial compressive load is applied to the fuel rods. Considering that in a pressurized water reactor fuel assembly, a similar compressive load is applied from each of the 7 to 9 support grids, the magnitude of the charge can be reduced to a fraction of -, which is sufficient to achieve the purpose of the present invention. achieved.

なお、支持格子と、上部又は下部端板との固定は、直接
結合部材を介して機械的手段で固定し、又は溶接などの
冶金的手段で固着することも可能であるが、スリーブを
利用し、構造部材に関連し、例えば制御棒案内管の外側
に該スリーブを機械的手段で固着し、このスリーブに対
して上部又は下部端板を冶金的手段で固着するなど、種
々の手段が使用される。Note that the support grid and the upper or lower end plate can be fixed by mechanical means via a direct coupling member or by metallurgical means such as welding, but it is also possible to fix the support grid to the upper or lower end plate by using a sleeve. , various means are used in relation to the structural members, such as fixing the sleeve to the outside of the control rod guide tube by mechanical means and fixing the upper or lower end plate to this sleeve by metallurgical means. Ru.

又、−上記固定される支持格子を除いた他の固定されて
いない支持格子の構造部材に対する相対的変位全所定の
範囲に制限することも望ましく、そのｋめ特に必須では
ないが、停止部利が設けられる。It is also desirable to limit the total relative displacement of the non-fixed support grid with respect to the structural members other than the fixed support grid, and for this purpose, although it is not particularly necessary, is provided.

停止部利け、例えば短尺のスリーブで構成され、構造部
材の外周に配置して構造部材に対して冶金的又は機械的
に結合するか、又は支柱状の管で構成し、構造部材の外
周部で少なくとも一定の部分上を滑動し、かつ支持格子
に当接して支持格子間に一定の間＠全維持するように作
られる。Stops, for example consisting of short sleeves arranged around the outer periphery of the structural member and connected metallurgically or mechanically thereto, or consisting of strut-like tubes, arranged around the outer periphery of the structural member It is made to slide over at least a certain portion of the support grid, and to be in contact with the support grid so as to remain between the support grids for a certain period of time.

以下、更に添付図面全参照し２、本発明の実施例につき
説明する。Hereinafter, embodiments of the present invention will be described with further reference to the accompanying drawings.

第１図は加圧水型原子炉燃料集合体の全体構造を示す概
観図、第２図は燃料棒の一部省略断面図、第３図乃至第
５図は本発明要部を示す平面図ならびに受は座圧面図、
平面図である。Fig. 1 is an overview diagram showing the overall structure of a pressurized water reactor fuel assembly, Fig. 2 is a partially omitted sectional view of a fuel rod, and Figs. 3 to 5 are plan views and receivers showing essential parts of the present invention. is the seating pressure surface diagram,
FIG.

又、第６図は支持格子と端板との固定態様の１例全示し
、第７図は停止部材の１例を示す。Moreover, FIG. 6 shows an example of the manner in which the support grid and the end plate are fixed, and FIG. 7 shows an example of the stop member.

第１図において（］、）　；　（２）は上部端板、下部
端板であり、これら両端板に区画されてその間に複数の
燃料棒（３）及び複数の制御棒案内管等の構造部材（４
）が正方格子状に配列され、軸方向に所定の間隔をおい
て配置された複数個の支持格子（５Ａ）〜（５Ｇ）によ
って夫々前記燃料棒（３）、構造部材（４）　ｋ　横方
向所定の配置になるよう保持し、燃料集合体全構成して
いる。In Fig. 1, (], ); (2) are an upper end plate and a lower end plate, which are divided into both end plates, and between which are structural members such as a plurality of fuel rods (3) and a plurality of control rod guide tubes. (4
) are arranged in a square lattice shape, and the fuel rods (3) and structural members (4) are connected to the fuel rods (3) and structural members (4), respectively, by a plurality of support grids (5A) to (5G) arranged at predetermined intervals in the axial direction. The entire fuel assembly is constructed by holding it in a predetermined position.

そして、上記支持格子（５Ａ）〜（５Ｇ）のうち、配列
された燃料の有効長、即ち第２図に図示しているが、燃
料被覆管（６）内に収納され、両端スプリング（８）に
よって保持されたペレット（７）の占める長さくａ）の
軸方向外方に位置する支持格子、第１図では最」二段及
び最下段の支持格子（５Ａ）　＋　（５Ｇ）は夫々上部
端板（１）、下部端板（２）に結合部材（９）を介して
溶接により固定されている。Of the support grids (5A) to (5G), the effective length of the arranged fuel, that is, as shown in FIG. In FIG. 1, the support grids (5A) + (5G) are the upper ends of the support grids located axially outward of the length a) occupied by the pellet (7) held by the It is fixed to the plate (1) and the lower end plate (2) by welding via a connecting member (9).

この場合、両者の固定は結合部材（９）によっているが
、例えば第６図にその１例を示す如く、スリーブ（９）
を用いて、構造部材（４）をなす制御棒案内管の外側に
該スリーブ（９５−ｘ機械的手段でかしめ付けて固着し
、スリーブ（９）に対して端板（１）又は（２）を溶接
等の冶金的手段で固着した構造とすることもできる。In this case, the two are fixed by a coupling member (9), and for example, as shown in FIG. 6, the sleeve (9)
The sleeve (95-x) is caulked and fixed by mechanical means to the outside of the control rod guide tube forming the structural member (4), and the end plate (1) or (2) is attached to the sleeve (9). It is also possible to have a structure in which the parts are fixed by metallurgical means such as welding.

一方、支持格子（５Ａ）〜（５Ｇ）は夫々、第３図に図
示するように互いに直交する縦横２群の金属薄板よりな
る帯板００）によって格子状に組立て構成されていて、
その縦横両群の帯板（１ｏ）によって燃料棒及び構造部
材を挿通するセル（１１）　、　（１３）　を区画形成
している。そして、このうち、燃料棒（３）を挿通する
セルを区画する４つの帯板壁面には反りに燃料棒を弾支
するばね部材（１２）が内面に突出しており、挿通され
る燃料棒（３）をそのばね力によって保持し得るように
なっている。On the other hand, each of the support grids (5A) to (5G) is constructed in a lattice-like manner by strip plates 00) made of two groups of metal thin plates orthogonal to each other, as shown in FIG.
The vertical and horizontal groups of strips (1o) define cells (11) and (13) through which fuel rods and structural members are inserted. Among these, spring members (12) that elastically support the fuel rods are protruded from the inner surfaces of the four strip walls that partition the cells into which the fuel rods (3) are inserted. 3) can be held by its spring force.

これに対し、構造部材（４）を挿通するセル０（６）に
は、その４つの壁面を構成する帯板内面に構造部材（４
）を受は止め保持する受は座（１４）が設けられている
。On the other hand, cell 0 (6) through which the structural member (4) is inserted has a structural member (4) on the inner surface of the strip that constitutes its four walls.
) is provided with a catch seat (14) for holding the catch.

この受は座（１→は前述の如く本発明における要部をな
し、帯板各面において、上下で他面側へばね部材０２）
全切出し形成している帯板α０）中間部位の内面側へ向
かって設けられ、前記構造部材（４）ヲその４個所で間
欠的に保持すると共に、その保持面を通る構造部材（４
）包囲面は構造部材外径と略等しいか、僅かに大きい内
径の円周状輪郭を形成し、構造部材を円周状輪郭に沿っ
て包囲保持する凹弧形状面となっている。This receiver is a seat (1→ constitutes a main part in the present invention as described above, and on each side of the band plate, there is a spring member 02 on the upper and lower sides of the other side)
The strip plate α0) which is completely cut out is provided toward the inner surface of the intermediate portion, and intermittently holds the structural member (4) at four locations, and the structural member (4) passes through the holding surface.
) The surrounding surface forms a circumferential contour with an inner diameter approximately equal to or slightly larger than the outer diameter of the structural member, and is a concave arc-shaped surface that surrounds and holds the structural member along the circumferential contour.

従って、構造部材（４）を該挿通セル（１３）内に挿通
す（ｌ→ るとき、構造部材（４）をその受けｔ３凹弧形状面によ
って円周状輪郭をもって保持することになる。Therefore, when the structural member (4) is inserted into the insertion cell (13), the structural member (4) is held with a circumferential contour by the concave arc-shaped surface of the receiving t3.

なお、第４図中、（１５）　ｉｊ：交叉する帯板挿入ス
リットである。又、第７図は特に固定された支持格子に
対し、固定されていない支持格子が構造部材に対し相対
的変位をする場合の、該相対的変位を所定の軸囲内に制
限するための停止部材の１例として構造部材（４）の外
周に構造部材に対して冶金的又は機械的に結合された短
尺のスリーブ（１６）を示している。この外、停止部材
は支柱状の管とし、構造部材の外周部で少くとも一定の
部分上を滑動し、かつ支持格子に当接して支持格子間に
一定の間隔を維持するようにしてもよい。そして、何れ
においても、相対的変位を所定範囲に制限するため第７
図に図示する如くストッパー（９）を形成する。特に構
造部材（４）である案内管には制御棒クラスタ案内シ／
プル（４Ａ）と炉内計装用案内シンプル（４Ｂ）がある
が、後者にこの構成が多く適用される。In FIG. 4, (15) ij: intersecting strip insertion slits. In addition, FIG. 7 shows a stop member for limiting the relative displacement within a predetermined axial circumference when an unfixed support grid is displaced relative to a structural member with respect to a fixed support grid. As an example, a short sleeve (16) is shown around the outer periphery of the structural member (4), which is metallurgically or mechanically bonded to the structural member. Alternatively, the stop member may be a strut-like tube that slides on at least a certain portion of the outer periphery of the structural member and abuts against the support grid to maintain a constant spacing between the support grids. . In either case, a seventh
A stopper (9) is formed as shown in the figure. In particular, the control rod cluster guide system is installed in the guide tube, which is the structural member (4).
There are pull (4A) and simple guide for in-core instrumentation (4B), and this configuration is often applied to the latter.

以上、添付図面にもとづいて本発明の詳細な説明したが
、本発明は更に、その目的を逸脱しない範囲において変
形又は改変が可能であることは勿論である。Although the present invention has been described above in detail based on the accompanying drawings, it goes without saying that the present invention can be further modified or modified without departing from its purpose.

かくして、本発明は叙上の構成により従来の欠点ヲ）イ
消し、本発明の目的を達成することができる。Thus, the present invention can eliminate the conventional drawbacks and achieve the object of the present invention with the above configuration.

以」−の妬く本発明燃料集合体は、特に構造部材を挿通
するセルを形成する支持格子帯板面に間欠的な円周状輪
郭をもつ剛な受は座を設置すると共に、燃料有効長外方
に位置する支持格子の少なくとも１個を上部又は下部端
板に対し固定せしめた構成力・らなっており、以下に述
べる如き諸効果を有している。In particular, the fuel assembly of the present invention is characterized in that rigid bearing seats with intermittent circumferential contours are installed on the surface of the support grid strips forming cells through which structural members are inserted, and the effective length of the fuel is At least one of the outer support grids is fixed to the upper or lower end plate, and has the following effects.

（１）燃料棒と共に支持格子が制御棒案内管等の構造部
材に対して自由に滑動するために燃料棒−がりの要因と
なるような軸方向圧縮荷重を燃料棒に付加することなく
、燃料棒を支持格子によって強く保持することができ、
冷却材の軸方向、横方向流れに対する燃料棒の振動を抑
制することができる０ （２）　　支持格子と構造部材との横方向の当接が剛な
受は座を介して行なわれるため、支持格子に横方向荷重
が作用するような場合の燃料集合体の横方向強度を大き
く維持することができる。(1) Because the support grid slides freely with the fuel rods against structural members such as control rod guide tubes, the fuel rods are not subject to any axial compressive loads that may cause the fuel rods to bulge. The rod can be strongly held by the support grid,
Vibration of the fuel rod due to the axial and lateral flow of coolant can be suppressed (2) Since the lateral contact between the support grid and the structural member is made through the rigid seat, the support It is possible to maintain a large lateral strength of the fuel assembly when a lateral load is applied to the grid.

（３）燃料集合体の軸方向外方に位置する支持格子の少
なくとも１個を端板に対して固定するため、燃ｆ１寿命
中の全期間にわたって冷却イオ喪失事故等の場合に燃料
棒ハンドルに加わる上向き荷重に対して燃料棒を軸方向
所定位置に保持することができ、充分に構造上の健全性
を維持することができる。(3) At least one of the support grids located axially outward of the fuel assembly is fixed to the end plate, so that it can be attached to the fuel rod handle in case of a cooling io loss accident etc. during the entire fuel f1 life. The fuel rods can be held in place in the axial direction against applied upward loads, and sufficient structural integrity can be maintained.

【図面の簡単な説明】[Brief explanation of the drawing]

第］−図は本発明に係る加圧水型原子炉麩料集合体の全
体構造を示す概観図、第２図は燃料棒の一部省略断面図
、第３図乃至第５図は本発明の要部をなす受は座を示す
図で、第３図は該受は座を設けた支持格子の部分平面図
、第４図は受は座圧面図、第５図は同平面図である。又
、第６図は支持格子に連なる構造部材と端板との固定態
様を示す説明図、第７図は停止部材の１例を示す説明図
である。 （］）・・・・・・・上部端板、（２）・・・・・下部
端板。 （３）・・・・・・燃料棒、（４）・・・・・・構造部
材。 （５）・・・・・・支持格子、（６）・・−・・・燃料
被覆管。 （７）・・・・・・・ペレット、　　（８）・・・・・
・スプリング。 （９）・・・・・・・結合部Ｎ、（９）・・・・・・固
定スリーブ。 （１０）・・・・・・帯　板＋　　　（］ｌ）・・・・
・・・燃料棒挿通セル。 （］２）・・・・・・ばね部材、０３）・・・・・・・
構造部材挿通セル。 ０→・・・・・・受は座、０６）・・・・・・・停止部
材。 （ａ）・・・・燃料有効長。Fig. 2 is a schematic diagram showing the overall structure of a pressurized water reactor material assembly according to the present invention, Fig. 2 is a partially omitted sectional view of a fuel rod, and Figs. 3 to 5 are main points of the present invention. 3 is a partial plan view of a support grid provided with a seat, FIG. 4 is a plan view of the support grid provided with the seat, FIG. 4 is a plan view of the support grid, and FIG. 5 is a plan view of the same. Further, FIG. 6 is an explanatory view showing a manner of fixing the structural member connected to the support grid and the end plate, and FIG. 7 is an explanatory view showing an example of the stop member. (])...Top end plate, (2)...Bottom end plate. (3)...Fuel rod, (4)...Structural member. (5)...Support grid, (6)...Fuel cladding tube. (7)・・・・・・Pellet, (8)・・・・・・
·spring. (9)......Connecting part N, (9)...Fixing sleeve. (10)...Band plate + (]l)...
...Fuel rod insertion cell. (]2)・・・Spring member, 03)・・・・・・
Structural member insertion cell. 0→...The receiver is the seat, 06)...The stop member. (a)...Fuel effective length.

Claims (1)

【特許請求の範囲】 ■、　複数の燃料棒と、複数の制御棒案内管等の構造部
材とを、軸方向所定の間隔をおいて配Ｎされた複数個の
支持格子によって横方向所定の配置になるよう構成せし
めた原子炉燃料集合体において、前記支持格子は互いに
直交する２群の金属薄板よりなる帯板によって格子状に
構成され、前記燃料棒及び前記構造部材の各々が挿通さ
れるセルを有し、前記構造部材が挿通されるセルを構成
する４つの壁面となる前記支持格子帯板部分には前記構
造部材に対する受は座が設けられ、該受は座は前記構造
部材が挿通される前記セル内に該構造部材を間欠的に保
持する円周状輪郭を形成して、その円周状輪郭の内径は
、そこに挿通される構造部材の外径と略等しいか、又は
僅かに大きく設定されていると共に、前記複数個の支持
格子のうち、燃料有効長の軸方向外方に位置する支持格
子の少くとも１個を前記構造部材に直接関連し、あるい
は他の結合部ｖＪを介して燃料集合体の全体構造を軸方
向で区画する上部端板又は下部端板に対して固定したこ
とを特徴とする原子炉燃料集合体。 ２、　支持格子を構成するｖＪ′ｐｌが構造部材を構成
する材料より熱膨張事大である特許請求の範囲第１項記
載の原子炉燃料集合体。 ８、　支持格子がステンレス鋼又はニッケル基合金であ
り、構造部材がジルコニウム合金である特許請求の範囲
第１項又は第２項記載の原子炉燃料集合体。 ４、　受は座か構造強度穴なる剛な部材である特許請求
の範囲第１項記載の原子炉燃料集合体。[Claims] (1) A plurality of fuel rods and structural members such as a plurality of control rod guide tubes are arranged in a predetermined lateral direction by a plurality of support grids arranged at predetermined intervals in the axial direction. In a nuclear reactor fuel assembly configured to The support grid strip portion, which is the four wall surfaces constituting the cell through which the structural member is inserted, is provided with a seat for the structural member, and the support grid plate portion is provided with a seat through which the structural member is inserted. A circumferential contour is formed to intermittently hold the structural member within the cell, and the inner diameter of the circumferential contour is approximately equal to or slightly equal to the outer diameter of the structural member inserted therein. At least one of the plurality of support grids located axially outward of the effective fuel length is directly related to the structural member or connected to another joint vJ. 1. A nuclear reactor fuel assembly, characterized in that the entire structure of the fuel assembly is fixed to an upper end plate or a lower end plate that partitions the entire structure of the fuel assembly in the axial direction. 2. The nuclear reactor fuel assembly according to claim 1, wherein vJ'pl constituting the support grid has a larger thermal expansion than the material constituting the structural members. 8. The nuclear reactor fuel assembly according to claim 1 or 2, wherein the support grid is made of stainless steel or a nickel-based alloy, and the structural member is made of a zirconium alloy. 4. The reactor fuel assembly according to claim 1, wherein the support is a rigid member such as a seat or a hole for structural strength.