JP2007232434A - Chimney structure in boiling-water reactor of natural circulation system - Google Patents

Chimney structure in boiling-water reactor of natural circulation system Download PDF

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JP2007232434A
JP2007232434A JP2006051799A JP2006051799A JP2007232434A JP 2007232434 A JP2007232434 A JP 2007232434A JP 2006051799 A JP2006051799 A JP 2006051799A JP 2006051799 A JP2006051799 A JP 2006051799A JP 2007232434 A JP2007232434 A JP 2007232434A
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chimney
cross
core
lattice
natural circulation
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JP4500276B2 (en
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Kenji Kanamori
健児 金森
Masaaki Tsubaki
椿　　正昭
Fumihito Hirokawa
文仁 廣川
Masaya Otsuka
雅哉 大塚
Shiro Takahashi
志郎 高橋
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Hitachi Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To improve the structural integrity of a chimney without remarkably increasing component materials or manufacturing costs. <P>SOLUTION: The chimney structure of a boiling water reactor of a natural circulation system which has a core loaded with fuel assemblies so that the cross section of the core is almost circular and with a chimney located above the core, is characterized in that the chimney is constituted by including a chimney trunk 11d, and a plurality of lattice channels 11a which are vertically placed inside the chimney trunk 11d, are partitioned by channel bulkheads 11b, and have rectangular cross sections, and that the lattice channels 11a include structures where some midpoint 102 in one side 101 of a cross-sectional rectangle 100 is supported by one side 201 of a cross-sectional rectangle 200 in an adjacent lattice flow channel 11a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、自然循環式沸騰水型原子炉に備えられるチムニの構造に関するものである。   The present invention relates to a chimney structure provided in a natural circulation boiling water reactor.

これまでに商業運転されている強制循環式の沸騰水型原子炉（以下、ＢＷＲという）では、円筒状の炉心シュラウド内に、横断面が正方形の燃料集合体をＸ軸方向、Ｙ方向（ともに水平方向）に並べて林立させて炉心を構成している。そして、横断面が略十字型の制御棒が、その周囲を囲む４体の燃料集合体の間に挿入可能に配置され、この制御棒を囲む４体の燃料集合体の単位を制御棒セルという。   In a forced circulation boiling water reactor (hereinafter referred to as BWR) that has been commercially operated so far, a fuel assembly having a square cross section is placed in a cylindrical core shroud in the X axis direction and the Y direction (both The core is composed of forests arranged horizontally. A control rod having a substantially cross-shaped cross section is disposed so as to be insertable between four fuel assemblies surrounding the periphery of the control rod. A unit of the four fuel assemblies surrounding the control rod is called a control rod cell. .

近年では、自然循環式ＢＷＲが提唱され、その自然循環式ＢＷＲでは自然循環の駆動力確保のため、炉心の上に強制循環式ＢＷＲには無いチムニが設けられる（例えば、特許文献１参照）。特許文献１に記載のチムニは、仕切り板により流路隔壁を構成して複数の格子流路を有している構成である。その場合、個々の燃料集合体に配分される冷却材流量は、下部プレナムから炉心へ流入時に各燃料集合体に分配され、燃料集合体を冷却して冷却材の気液二相流となり、さらに個々の燃料集合体を出てチムニの格子流路内で合流してチムニを通過後、上部プレナムで各格子流路の気液二相流全体が合流するまでの間の燃料集合体圧損と格子流路の圧損と、格子流路内のボイド率により主にきまる冷却材比重差による駆動力で決まる。   In recent years, a natural circulation type BWR has been proposed, and in the natural circulation type BWR, a chimney that does not exist in the forced circulation type BWR is provided on the core in order to ensure the driving force of the natural circulation (see, for example, Patent Document 1). The chimney described in Patent Document 1 has a configuration in which a flow path partition wall is configured by a partition plate to have a plurality of lattice flow paths. In that case, the coolant flow rate distributed to the individual fuel assemblies is distributed to each fuel assembly when it flows into the core from the lower plenum, cooling the fuel assembly to become a gas-liquid two-phase flow of coolant, Fuel assembly pressure loss and lattice after the individual fuel assemblies are merged in the chimney lattice channels and after passing through the chimney, until the entire gas-liquid two-phase flow in each lattice channel is merged in the upper plenum. It is determined by the driving force due to the difference in specific gravity of the coolant mainly determined by the pressure loss of the flow path and the void ratio in the lattice flow path.

ここで、チムニの格子流路に冷却材の気液二相流が流れると、流体力による振動（流力振動）が発生する。流力振動は、格子流路を形成する流路隔壁に応力を与えるため、流路隔壁にはこの応力に対抗すべく高い構造健全性が要求される。そして、流路隔壁の構造健全性を向上させるためには、一般に、流路隔壁の厚さを厚くしたり、流路隔壁が形成する格子流路の断面積を小さくしたりすることによって、実現することができる。
なお、従来の自然循環式ＢＷＲにおけるチムニ構造は、図４に示すように、横断面において格子流路が正方格子状に配列したものである。
特公平７−２７０５１号公報（第１図、第２図） Here, when a gas-liquid two-phase flow of the coolant flows through the chimney lattice flow, vibration due to fluid force (fluid vibration) occurs. Since the hydrodynamic vibration gives stress to the flow path partition walls forming the lattice flow paths, the flow path partition walls are required to have high structural integrity to counter this stress. And in order to improve the structural soundness of the channel partition, it is generally realized by increasing the thickness of the channel partition or reducing the cross-sectional area of the lattice channel formed by the channel partition. can do.
As shown in FIG. 4, the chimney structure in the conventional natural circulation type BWR has lattice channels arranged in a square lattice pattern in the cross section.
Japanese Patent Publication No. 7-27051 (FIGS. 1 and 2)

しかしながら、流路隔壁の厚さを厚くすると、チムニを構成する材料及び製作コストが増加してしまうという問題があった。また、流路隔壁が形成する格子流路の断面積を小さくした場合でも、流路隔壁の総数（総面積）が増加するために、結局のところチムニを構成する材料及び製作コストが増加してしまうという問題があった。   However, when the thickness of the flow path partition is increased, there is a problem that the material constituting the chimney and the manufacturing cost increase. Moreover, even when the cross-sectional area of the lattice flow path formed by the flow path partition is reduced, the total number (total area) of the flow path partition increases, which eventually increases the materials and manufacturing costs that make up Chimney. There was a problem that.

そこで、本発明は、構成する材料及び製作コストを特に増やすことなく、チムニの構造健全性を向上させることを課題とする。   Therefore, an object of the present invention is to improve the structural soundness of chimneys without particularly increasing the constituent materials and manufacturing costs.

前記課題を解決するため本発明は、複数の燃料集合体を横断面が円形状に装荷した炉心と、前記炉心の上に設置されたチムニを備えた自然循環式沸騰水型原子炉のチムニ構造であって、前記チムニは、チムニ胴と、前記チムニ胴の内部に垂設された流路隔壁により区画される横断面矩形の複数の格子流路を含んでなり、前記複数の格子流路において、前記横断面矩形の一辺の途中が、隣接する前記横断面矩形の一辺によって支持される構成である。   In order to solve the above-mentioned problems, the present invention provides a chimney structure of a natural circulation boiling water reactor comprising a core in which a plurality of fuel assemblies are loaded in a circular cross section, and a chimney installed on the core. The chimney includes a chimney cylinder and a plurality of grid channels having a rectangular cross section partitioned by a channel partition wall suspended in the chimney cylinder, The middle of one side of the cross section rectangle is supported by one side of the adjacent cross section rectangle.

本発明によれば、構成する材料及び製作コストを特に増やすことなく、チムニの構造健全性を向上させることができる。   According to the present invention, the structural soundness of chimney can be improved without particularly increasing the constituent materials and production costs.

以下、本発明を実施するための最良の形態（以下「実施形態」という）について、適宜図面を参照しながら詳細に説明する。
本発明は、チムニの流路隔壁の一面において、冷却材の気液二相流が及ぼす圧力変動が、流力振動の加振力になるという知見に基づいて創作されたものである。流力振動を低減させることができれば、流路隔壁にかかる最大応力が低減し、チムニの構造健全性を向上させることができる。
《第１の実施形態》
第１の実施形態に係る自然循環式沸騰水型原子炉のチムニ構造について、図１及び図２を参照しながら詳細に説明する。第１の実施形態の説明においては、まず、チムニを備えた原子炉の概要について説明し、その後、本実施形態において特徴的なチムニ構造について詳細に説明する。 Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate.
The present invention was created on the basis of the knowledge that the pressure fluctuation exerted by the gas-liquid two-phase flow of the coolant becomes the excitation force of the hydrodynamic vibration on one surface of the chimney channel partition. If the hydrodynamic vibration can be reduced, the maximum stress applied to the flow path partition can be reduced, and the structural integrity of the chimney can be improved.
<< First Embodiment >>
The chimney structure of the natural circulation boiling water reactor according to the first embodiment will be described in detail with reference to FIGS. 1 and 2. In the description of the first embodiment, first, an outline of a nuclear reactor equipped with chimney will be described, and then a characteristic chimney structure in the present embodiment will be described in detail.

（原子炉の概要）
一般に、沸騰水型原子炉内の冷却材（軽水）の駆動方法は２通りあり、一方は再循環ポンプを用いて強制循環させる方法であり、他方は再循環ポンプを用いないで自然循環による方法である。本実施形態は、後者の自然循環による方法である。
自然循環による方法は、図１に示すように、原子炉圧力容器（以下、圧力容器という）６内に収納する炉心７で発生するボイド、すなわち蒸気（気相）と飽和温度の液相の冷却材の混合した密度の低い冷却材と、給水配管１６ｂから供給される給水と混合された液相の冷却材との比重差によって自然循環に必要な駆動力を得るものである。 (Outline of the reactor)
In general, there are two methods for driving coolant (light water) in a boiling water reactor, one is forced circulation using a recirculation pump, and the other is natural circulation without using a recirculation pump. It is. This embodiment is the latter method based on natural circulation.
As shown in FIG. 1, the natural circulation method is a method of cooling voids generated in a reactor core 7 housed in a reactor pressure vessel (hereinafter referred to as a pressure vessel) 6, that is, vapor (gas phase) and a liquid phase having a saturation temperature. A driving force necessary for natural circulation is obtained by a difference in specific gravity between the coolant having a low density mixed with the material and the liquid phase coolant mixed with the water supplied from the water supply pipe 16b.

図１に示すように本実施形態の自然循環式沸騰水型原子炉（以下、原子炉という）１は、円筒状の圧力容器６内に、炉心シュラウド８が、同心の円筒状に設けられている。この炉心シュラウド８は、その外側面と圧力容器６の内側面との間隙に環状空間を形成し、これをダウンカマ９という。また、炉心シュラウド８の内部には、多数の燃料集合体２１が配置された炉心７を収容している。   As shown in FIG. 1, a natural circulation boiling water reactor (hereinafter referred to as “reactor”) 1 according to the present embodiment has a core shroud 8 provided in a cylindrical pressure vessel 6 in a concentric cylindrical shape. Yes. The core shroud 8 forms an annular space in the gap between the outer side surface and the inner side surface of the pressure vessel 6, and this is called a downcomer 9. Further, the core 7 in which a large number of fuel assemblies 21 are arranged is housed inside the core shroud 8.

ダウンカマ９の上方には、復水器３から給水ポンプ４を介して、給水加熱器５で加熱の後、給水入口ノズル１７から圧力容器６内に供給される冷却材を圧力容器６内に均等に配分する図示しない給水スパージャが円環状に設けられている。
炉心シュラウド８は、シュラウドレグ８ａによって支持される。ダウンカマ９を下降した冷却材は、シュラウドレグ８ａ間の流路から、炉心７の下部の炉心下部プレナム（以下、下部プレナムという）１０に導き入れられる。 Above the downcomer 9, the coolant supplied from the feed water inlet nozzle 17 into the pressure vessel 6 after being heated by the feed water heater 5 from the condenser 3 via the feed water pump 4 is evenly placed in the pressure vessel 6. A water supply sparger (not shown) is provided in an annular shape.
The core shroud 8 is supported by a shroud leg 8a. The coolant descending the downcomer 9 is introduced into the core lower plenum (hereinafter referred to as the lower plenum) 10 below the core 7 from the flow path between the shroud legs 8a.

炉心７の下部には、炉心支持板２２を、上部には、上部格子板２３を設け、燃料集合体２１と制御棒２４の横方向の配置を決めている。
炉心支持板２２には、所定の間隔で円形の図示しない貫通孔が設けられ、その貫通孔に制御棒案内管２５が挿入され、制御棒案内管２５の下部は、圧力容器６の底部を貫通して制御棒２４を上下方向に動かす制御棒駆動機構（以下、ＣＲＤという）２６を収容する制御棒駆動機構ハウジング（以下、ＣＲＤハウジングという）２６ａの上部に組合わされている。
燃料集合体２１は、制御棒案内管２５の上端に取り付けられた図示しない燃料支持金具の上に据えられ、その荷重は制御棒案内管２５およびＣＲＤハウジング２６ａを介して、圧力容器６の底部に伝えられる。 A core support plate 22 is provided in the lower part of the core 7 and an upper lattice plate 23 is provided in the upper part, and the lateral arrangement of the fuel assemblies 21 and the control rods 24 is determined.
The core support plate 22 is provided with circular through holes (not shown) at predetermined intervals. A control rod guide tube 25 is inserted into the through holes, and the lower portion of the control rod guide tube 25 penetrates the bottom of the pressure vessel 6. Thus, it is combined with an upper part of a control rod drive mechanism housing (hereinafter referred to as CRD housing) 26a that houses a control rod drive mechanism (hereinafter referred to as CRD) 26 that moves the control rod 24 in the vertical direction.
The fuel assembly 21 is placed on a fuel support bracket (not shown) attached to the upper end of the control rod guide tube 25, and the load is applied to the bottom of the pressure vessel 6 via the control rod guide tube 25 and the CRD housing 26a. Reportedly.

前記の図示しない燃料支持金具は、側面に冷却材入口を有し、そこに図示しないオリフィスが設けられて、冷却材流量を規制している。燃料支持金具の冷却材入口に対応する制御棒案内管２５の側面には開口が設けられ、下部プレナム１０に導かれた冷却材が燃料支持金具を経て、燃料集合体２１内に導かれる。
個々の燃料集合体２１は、図示しない四角筒のチャンネルボックスで囲われ軸方向の個別の流路を形成しており、チャンネルボックスは上部格子板２３の上面まで到る構成をしている。
前記制御棒２４は図示しない中性子吸収物質を含む有効部を有し、その有効部が前記チャンネルボックスの外面をガイドとして、周囲の４体の燃料集合体２１間に挿入される。 The fuel support fitting (not shown) has a coolant inlet on a side surface, and an orifice (not shown) is provided there to regulate the coolant flow rate. An opening is provided in the side surface of the control rod guide tube 25 corresponding to the coolant inlet of the fuel support bracket, and the coolant guided to the lower plenum 10 is guided into the fuel assembly 21 through the fuel support bracket.
Each fuel assembly 21 is surrounded by a rectangular tube channel box (not shown) to form individual flow paths in the axial direction, and the channel box is configured to reach the upper surface of the upper lattice plate 23.
The control rod 24 has an effective portion containing a neutron absorbing material (not shown), and the effective portion is inserted between the surrounding four fuel assemblies 21 using the outer surface of the channel box as a guide.

炉心７の上には、炉心から出た冷却材の気液二相流を上方に導き自然循環駆動力を増加させるチムニ１１が設けられている。チムニ１１は、例えば圧力容器６と同心の円筒状のチムニ胴１１ｄを有し、その内部を仕切り板で格子状に仕切った格子流路１１ａを有している。以下では、格子流路１１ａを構成する前記仕切り板を流路隔壁１１ｂという。
なお、個々の格子流路１１ａを上方に流れる冷却材がチムニ１１内の上部で合流するように、チムニ１１の上部に上部プレナム１１ｃが設けられている。
なお、上部格子板２３とチムニ１１の下端とは、ダウンカマ９を下降する冷却材と、炉心７を出た冷却材とが混じらないような組み合わせ構造となっている。 Provided on the core 7 is a chimney 11 for guiding the gas-liquid two-phase flow of the coolant coming out of the core upward and increasing the natural circulation driving force. The chimney 11 has, for example, a cylindrical chimney cylinder 11d concentric with the pressure vessel 6, and has a lattice channel 11a in which the inside is partitioned into a lattice shape by a partition plate. Hereinafter, the partition plate constituting the lattice channel 11a is referred to as a channel partition wall 11b.
In addition, the upper plenum 11c is provided in the upper part of the chimney 11 so that the coolant flowing upward through the individual lattice channels 11a merges in the upper part of the chimney 11.
The upper lattice plate 23 and the lower end of the chimney 11 have a combined structure in which the coolant that descends the downcomer 9 and the coolant that exits the core 7 are not mixed.

チムニ１１の上端は、チムニヘッド１２ａで閉じられる。チムニヘッド１２ａには、所定の数の冷却材通過用の孔が設けられ、その孔はスタンドパイプ１２ｂを介して気液二相流から飽和蒸気と飽和水とを分離する気水分離器１２につながっている。気水分離器１２の上方には、蒸気乾燥器１３が設けられ、気水分離器１２を出た飽和蒸気に含まれる湿分を除去する。蒸気乾燥機１３を通過した蒸気は、蒸気ドーム１４、蒸気出口ノズル１５、主蒸気配管１６ａを経て、タービン２に送られる。
なお、チムニヘッド１２ａとスタンドパイプ１２ｂと気水分離器１２は一体に組み立てられており、燃料交換時には、一体でチムニ１１の上端から取り外し可能な構成となっている。 The upper end of the chimney 11 is closed by a chimney head 12a. The chimney head 12a is provided with a predetermined number of coolant passage holes, and the holes are connected to a steam / water separator 12 that separates saturated steam and saturated water from the gas / liquid two-phase flow through a stand pipe 12b. ing. A steam dryer 13 is provided above the steam / water separator 12 to remove moisture contained in the saturated steam exiting the steam / water separator 12. The steam that has passed through the steam dryer 13 is sent to the turbine 2 via the steam dome 14, the steam outlet nozzle 15, and the main steam pipe 16a.
The chimney head 12a, the stand pipe 12b, and the steam / water separator 12 are integrally assembled, and are configured to be integrally removable from the upper end of the chimney 11 when the fuel is changed.

このように、概略説明した原子炉１においては、給水入口ノズル１７から供給される冷却材は、気水分離器１２で分離された飽和水と混合し、図１中矢印Ａで示される冷却材は、ダウンカマ９を下降し、シュラウドレグ８ａの図示しない間隙によって構成される流路から、炉心シュラウド８内に流入し、炉心７によって加熱される。炉心７からの加熱によって冷却材Ａは、矢印Ｂで示す飽和状態の気液二相流となり、この気液二相流は格子流路１１ａ、上部プレナム１１ｃ、スタンドパイプ１２ｂを経て、気水分離器１２によって、矢印Ｃで示す気相の飽和蒸気と、矢印Ｄで示す液相の飽和水に分離される。飽和蒸気Ｃは、蒸気乾燥器１３を経て、蒸気出口ノズル１５から主蒸気配管１６ａによってタービン２に導かれ発電に供される。
一方、飽和水Ｄは、圧力容器６内の冷却材に混合され、給水入口ノズル１７から供給される冷却材と更に混合されて、再びダウンカマ９を下降して圧力容器５内を循環する。 Thus, in the nuclear reactor 1 schematically described, the coolant supplied from the feed water inlet nozzle 17 is mixed with the saturated water separated by the steam separator 12, and the coolant indicated by the arrow A in FIG. Moves down the downcomer 9, flows into the core shroud 8 from a flow path formed by a gap (not shown) of the shroud leg 8 a, and is heated by the core 7. By the heating from the core 7, the coolant A becomes a saturated gas-liquid two-phase flow indicated by an arrow B, and this gas-liquid two-phase flow passes through the lattice channel 11a, the upper plenum 11c, and the stand pipe 12b to separate the gas and water. The vessel 12 separates the gas phase saturated steam indicated by the arrow C and the liquid phase saturated water indicated by the arrow D. The saturated steam C passes through the steam dryer 13, is led from the steam outlet nozzle 15 to the turbine 2 through the main steam pipe 16 a, and is used for power generation.
On the other hand, the saturated water D is mixed with the coolant in the pressure vessel 6, further mixed with the coolant supplied from the feed water inlet nozzle 17, and descends the downcomer 9 again to circulate in the pressure vessel 5.

（チムニ１１の格子流路１１ａの構成）
次に、図２を参照（適宜、図１を参照）し、チムニ１１の横断面（以下、チムニ横断面という）の詳細な構成を説明する。
図２に示すように、チムニ１１は、圧力容器６（図１参照）と同心の円筒状のチムニ胴１１ｄを有し、その内部を仕切り板等の流路隔壁１１ｂで格子状に仕切った格子流路１１ａを有している。格子流路１１ａを構成する流路隔壁１１ｂは、例えばステンレス鋼等の、金属からなる。 (Configuration of the lattice channel 11a of the chimney 11)
Next, referring to FIG. 2 (refer to FIG. 1 as appropriate), a detailed configuration of the cross section of the chimney 11 (hereinafter referred to as chimney cross section) will be described.
As shown in FIG. 2, the chimney 11 has a cylindrical chimney cylinder 11d concentric with the pressure vessel 6 (see FIG. 1), and the inside of the chimney 11 is divided into a lattice shape by a flow path partition 11b such as a partition plate. It has a flow path 11a. The channel partition walls 11b constituting the lattice channel 11a are made of metal such as stainless steel.

ここで、格子流路１１ａの流路隔壁１１ｂは、原子炉の定期検査の際に、チムニ１１を圧力容器６の内部に設置したまま、格子流路１１ａを通じて燃料集合体２１などの交換作業を行う観点から、炉心７の上部格子板２３の前記制御棒セル単位で開けられた正方形の格子孔を横切るような形で塞がないように構成することが好ましい。なお、制御棒セルとは、横断面が略十字型の制御棒と、制御棒を囲む４体の燃料集合体とによって構成される単位である。
そして、図２における各格子流路１１ａの横断面の大きさは、炉心７（図１参照）に配置された４×４配列の燃料集合体２１に対応する。すなわち、各格子流路１１ａの横断面の大きさは、２×２配列の制御棒セルに対応する。従って、図２に示すチムニ横断面の構成は、格子流路１１ａを通じた燃料集合体２１などの交換作業を妨げるものではない。 Here, the flow path partition wall 11b of the lattice flow path 11a allows the fuel assembly 21 and the like to be exchanged through the lattice flow path 11a while the chimney 11 is installed inside the pressure vessel 6 during the periodic inspection of the nuclear reactor. From the viewpoint of performing, it is preferable that the upper lattice plate 23 of the core 7 is configured not to be blocked in such a manner as to cross the square lattice holes opened in units of the control rod cells. The control rod cell is a unit composed of a control rod having a substantially cross-shaped cross section and four fuel assemblies surrounding the control rod.
2 corresponds to the 4 × 4 array of fuel assemblies 21 arranged in the core 7 (see FIG. 1). That is, the size of the cross section of each lattice channel 11a corresponds to a 2 × 2 array of control rod cells. Therefore, the configuration of the chimney cross section shown in FIG. 2 does not hinder the replacement operation of the fuel assembly 21 and the like through the lattice channel 11a.

そして、第１の実施形態のチムニ構造は、格子流路１１ａの横断面において、前記したように所定の大きさを有する正方形の格子流路１１ａが千鳥配列となっている。その結果、例えば、正方形１００の対向する一組の二辺１０１，１０１は、辺の中間点（途中）１０２，１０２において、それぞれ隣接する他の正方形２００，２００の一辺２０１，２０１によって支持されることとなる。   In the chimney structure of the first embodiment, as described above, the square lattice channels 11a having a predetermined size are arranged in a staggered manner in the cross section of the lattice channel 11a. As a result, for example, a pair of opposite sides 101 and 101 of the square 100 are supported by the sides 201 and 201 of other adjacent squares 200 and 200 at the intermediate points (intermediates) 102 and 102 of the sides, respectively. It will be.

通常、対向する１対の二辺が支持されてもう１対の二辺が自由な長方形板（流路隔壁１１ｂの一面）が等分布荷重を受ける場合、最大たわみは支持された辺と辺との中間（自由な二辺を等間隔に分割する地点を結ぶ線上）に、最大応力は支持された辺に、それぞれ発生する。そして、この最大たわみ及び最大応力は、自由な二辺の長さが長いほど大きい値となる。従って、圧力変動による荷重を受ける場合、第１の実施形態の格子流路１１ａの構成によれば、長方形板である流路隔壁１１ｂの一面において、自由な二辺の長さを従来の半分にすることができるため、最大たわみ及び最大応力も低減させることができる。
なお、第１の実施形態のチムニ構造において、正方形１００のもう一組の対向する二辺１０３，１０３の途中は、特に他の正方形の一辺によって支持されてはいない。 In general, when a rectangular plate (one surface of the channel partition wall 11b) in which a pair of opposing two sides is supported and the other pair of two sides is free is subjected to a uniform load, the maximum deflection is the supported side and side. The maximum stress is generated on each of the supported sides in the middle (on the line connecting the points dividing the two free sides at equal intervals). The maximum deflection and the maximum stress increase as the length of the free two sides increases. Therefore, when receiving a load due to pressure fluctuation, according to the configuration of the lattice flow path 11a of the first embodiment, the length of two free sides on the one surface of the flow path partition wall 11b which is a rectangular plate is halved compared to the conventional one. Therefore, the maximum deflection and the maximum stress can be reduced.
In the chimney structure of the first embodiment, the middle of another pair of opposite sides 103, 103 of the square 100 is not particularly supported by one side of another square.

以上のように第１の実施形態によれば、流路隔壁１１ｂの一面において支持点を増加させることによって最大応力を低減させ、チムニの構造健全性を向上させることができる。   As described above, according to the first embodiment, the maximum stress can be reduced by increasing the support points on one surface of the flow path partition wall 11b, and the structural integrity of chimney can be improved.

《第２の実施形態》
次に、本発明の第２の実施形態に係る自然循環式沸騰水型原子炉のチムニについて、図３を参照しながら詳細に説明する。第２の実施形態は、第１の実施形態と比べ、チムニ内の格子流路１１ａの配列が異なるのみである。従って、第２の実施形態に特徴的な部分については詳細に説明するが、重複する説明は省略する。 << Second Embodiment >>
Next, chimney of a natural circulation boiling water reactor according to the second embodiment of the present invention will be described in detail with reference to FIG. The second embodiment is different from the first embodiment only in the arrangement of the lattice channels 11a in the chimney. Therefore, the characteristic features of the second embodiment will be described in detail, but overlapping descriptions will be omitted.

図３に示すように、格子流路１１ａの横断面は、断面積の大きい正方形３００と、断面積の小さい正方形４００との、２種類の大きさの正方形からなる。正方形３００の大きさは、第１の実施形態と同様に、炉心７（図１参照）に配置された４×４配列の燃料集合体２３に対応する。すなわち、各格子流路１１ａの横断面の大きさは、２×２配列の制御棒セルに対応する。また、正方形４００の大きさは、炉心７（図１参照）に配置された２×２配列の燃料集合体２１に対応する。すなわち、各格子流路１１ａの横断面の大きさは、制御棒セル単位に対応する。従って、各格子流路１１ａの横断面が、正方形３００及び正方形４００のどちらであっても、格子流路１１ａを通じた燃料集合体２１などの交換作業を妨げるものではない。   As shown in FIG. 3, the cross section of the lattice channel 11a is composed of two types of squares, a square 300 having a large cross-sectional area and a square 400 having a small cross-sectional area. The size of the square 300 corresponds to the 4 × 4 array of fuel assemblies 23 arranged in the core 7 (see FIG. 1), as in the first embodiment. That is, the size of the cross section of each lattice channel 11a corresponds to a 2 × 2 array of control rod cells. The size of the square 400 corresponds to the 2 × 2 array of fuel assemblies 21 arranged in the core 7 (see FIG. 1). That is, the size of the cross section of each lattice channel 11a corresponds to a control rod cell unit. Therefore, even if the cross section of each lattice channel 11a is either the square 300 or the square 400, it does not hinder the replacement operation of the fuel assembly 21 and the like through the lattice channel 11a.

そして、第２の実施形態のチムニ構造は、格子流路１１ａの横断面において、前記したように正方形３００の格子流路１１ａと正方形４００の格子流路１１ａとが、交互に配列している。言い換えると、正方形４００の格子流路１１ａは、４つの正方形３００の格子流路１１ａに囲まれて配列している。その結果、例えば、正方形３００の四つの辺３０１，…，３０１は、辺の中間点３０２，…，３０２において、それぞれ隣接する正方形４００，…，４００の一辺４０１，…，４０１によって支持されることとなる。   In the chimney structure of the second embodiment, the grid channels 11a of the square 300 and the grid channels 11a of the square 400 are alternately arranged in the cross section of the grid channel 11a as described above. In other words, the lattice channels 11 a of the square 400 are surrounded by the lattice channels 11 a of the four squares 300 and arranged. As a result, for example, the four sides 301,..., 301 of the square 300 are supported by the sides 401,. It becomes.

通常、対向する１対の二辺が支持されてもう１対の二辺が長方形板（流路隔壁１１ｂの一面）が等分布荷重を受ける場合、最大たわみは支持された辺と辺との中間（自由な二辺を等間隔に分割する地点を結ぶ線上）に、最大応力は支持された辺に、それぞれ発生する。そして、この最大たわみ及び最大応力は、自由な二辺の長さが長いほど大きい値となる。従って、圧力変動による荷重を受ける場合、第２の実施形態の格子流路１１ａの構成によれば、長方形板である流路隔壁１１ｂの一面において、自由な二辺の長さを従来の半分にすることができるため、最大たわみ及び最大応力も低減させることができる。なお、第２の実施形態のチムニ構造において、正方形４００の四辺４０１，…，４０１の途中は、特に他の正方形の一辺によって支持されてはいない。   Usually, when one pair of opposite sides is supported and the other two sides are rectangular plates (one surface of the channel partition wall 11b) receive a uniform load, the maximum deflection is between the supported sides. Maximum stress is generated on each of the supported sides (on a line connecting points where two free sides are equally spaced). The maximum deflection and maximum stress increase as the length of the free two sides increases. Therefore, when receiving a load due to pressure fluctuations, according to the configuration of the lattice channel 11a of the second embodiment, the length of two free sides is halved on the one surface of the channel partition wall 11b which is a rectangular plate. Therefore, the maximum deflection and the maximum stress can be reduced. In the chimney structure of the second embodiment, the middle of the four sides 401,..., 401 of the square 400 is not particularly supported by one side of another square.

以上のように第２の実施形態によれば、流路隔壁１１ｂの一面において支持点を増加させることによって最大応力を低減させ、チムニの構造健全性を向上させることができる。
また、第１の実施形態においては、正方形の二辺の中間点をそれぞれ隣接する正方形の一辺で支持するのみであったが、第２の実施形態においては、正方形の四辺の中間点をそれぞれ隣接する正方形の一辺で支持することができる。 As described above, according to the second embodiment, the maximum stress can be reduced by increasing the support points on one surface of the flow path partition wall 11b, and the structural integrity of chimney can be improved.
Further, in the first embodiment, the intermediate points of the two sides of the square are only supported by one side of the adjacent square. However, in the second embodiment, the intermediate points of the four sides of the square are adjacent to each other. Can be supported on one side of the square.

なお、本実施形態において、正方形の一辺の途中を中間点として示したが、思想を逸脱しない範囲でずらしてもよい。また、本実施形態において、格子流路１１ａの横断面を正方形として説明したが、例えば長方形等の矩形であればよい。   In the present embodiment, the middle of one side of the square is shown as an intermediate point, but may be shifted within a range that does not depart from the idea. Moreover, in this embodiment, although the cross section of the lattice flow path 11a was demonstrated as a square, it should just be rectangles, such as a rectangle, for example.

第１の実施形態の自然循環式沸騰水型原子炉の縦断面の模式図である。It is a schematic diagram of the longitudinal cross-section of the natural circulation type boiling water reactor of 1st Embodiment. 第１の実施形態のチムニ構造を説明するための図であって、図１のＧ−Ｇ横断面図である。It is a figure for demonstrating the chimney structure of 1st Embodiment, Comprising: It is GG cross-sectional view of FIG. 第２の実施形態のチムニ構造を説明するための図であって、図１のＧ−Ｇ横断面図である。It is a figure for demonstrating the chimney structure of 2nd Embodiment, Comprising: It is the GG cross-sectional view of FIG. 従来の自然循環式ＢＷＲにおけるチムニ構造を示す横断面図である。It is a cross-sectional view showing a chimney structure in a conventional natural circulation type BWR.

符号の説明Explanation of symbols

１ 自然循環式沸騰水型原子炉
２ タービン
３ 復水気
４ 給水ポンプ
５ 給水加熱器
６ 原子炉圧力容器
７ 炉心
８ 炉心シュラウド
９ ダウンカマ
１０ 炉心下部プレナム
１１ チムニ
１１ａ 格子流路
１１ｂ 流路隔壁
１１ｃ 上部プレナム
１１ｄ チムニ胴
１２ 気水分離器
１２ａ チムニヘッド
１２ｂ スタンドパイプ
１３ 蒸気乾燥器
１４ 蒸気ドーム
１５ ビーム伝送ダクト
１５ 蒸気出口ノズル
１６ａ 主蒸気配管
１６ｂ 給水配管
１７ 給水入口ノズル
２１ 燃料集合体
２２ 炉心支持板
２３ 上部格子板
２４ 制御棒
２５ 制御棒案内管
２６ 制御棒駆動機構
２６ａ 制御棒駆動機構ハウジング
１００，２００，３００，４００ 正方形（横断面矩形） DESCRIPTION OF SYMBOLS 1 Natural circulation type boiling water reactor 2 Turbine 3 Condensate 4 Feed water pump 5 Feed water heater 6 Reactor pressure vessel 7 Core 8 Core shroud 9 Downcomer 10 Core lower plenum 11 Chimni 11a Grid channel 11b Channel partition 11c Upper plenum 11d chimney cylinder 12 steam separator 12a chimney head 12b stand pipe 13 steam dryer 14 steam dome 15 beam transmission duct 15 steam outlet nozzle 16a main steam pipe 16b water supply pipe 17 water inlet nozzle 21 fuel assembly 22 core support plate 23 upper grid Plate 24 Control rod 25 Control rod guide tube 26 Control rod drive mechanism 26a Control rod drive mechanism housing 100, 200, 300, 400 Square (cross-sectional rectangle)

Claims (4)

複数の燃料集合体を横断面が円形状に装荷した炉心と、前記炉心の上に設置されたチムニを備えた自然循環式沸騰水型原子炉のチムニ構造であって、
前記チムニは、チムニ胴と、前記チムニ胴の内部に垂設された流路隔壁により区画される横断面矩形の複数の格子流路を含んでなり、
前記複数の格子流路において、
前記横断面矩形の一辺の途中が、隣接する前記横断面矩形の一辺によって支持される構成を含むことを特徴とする自然循環式沸騰水型原子炉のチムニ構造。 A chimney structure of a natural circulation boiling water reactor comprising a core in which a cross section of a plurality of fuel assemblies is loaded in a circular shape, and a chimney installed on the core,
The chimney comprises a chimney cylinder and a plurality of lattice channels having a rectangular cross section defined by a channel partition wall suspended from the chimney cylinder,
In the plurality of lattice channels,
A chimney structure for a natural circulation boiling water reactor, characterized in that the middle of one side of the cross-sectional rectangle includes a structure supported by one side of the adjacent cross-sectional rectangle. 前記複数の格子流路において、
複数の前記横断面矩形が、千鳥配列であることを特徴とする請求項１に記載の自然循環式沸騰水型原子炉のチムニ構造。 In the plurality of lattice channels,
The chimney structure of a natural circulation boiling water reactor according to claim 1, wherein the plurality of rectangular cross sections are in a staggered arrangement. 前記複数の格子流路において、
複数の前記横断面矩形が、第一の横断面矩形と、該第一の横断面矩形よりも面積の小さい第二の横断面矩形を含んでなり、
前記第一の横断面矩形の一辺の途中が、隣接する前記第二の横断面矩形の一辺によって支持される構成を含むことを特徴とする請求項１に記載の自然循環式沸騰水型原子炉のチムニ構造。 In the plurality of lattice channels,
The plurality of cross-sectional rectangles include a first cross-sectional rectangle and a second cross-sectional rectangle having a smaller area than the first cross-sectional rectangle,
2. The natural circulation boiling water reactor according to claim 1, wherein a middle part of one side of the first cross-sectional rectangle includes a structure supported by one side of the adjacent second cross-sectional rectangle. Chimney structure. 前記複数の格子流路において、
前記横断面矩形の各辺の長さは、前記炉心に配置された制御棒と該制御棒を囲む４体の燃料集合体を含んでなる制御棒セルを横断面視した矩形の各辺を整数倍した長さに対応することを特徴とする請求項１ないし請求項３のいずれか一項に記載の自然循環式沸騰水型原子炉のチムニ構造。 In the plurality of lattice channels,
The length of each side of the transverse cross-sectional rectangle is an integer of each side of the rectangular cross-sectional view of the control rod cell including the control rod disposed in the core and the four fuel assemblies surrounding the control rod. The chimney structure for a natural circulation boiling water nuclear reactor according to any one of claims 1 to 3, wherein the chimney structure corresponds to the doubled length.
JP2006051799A 2006-02-28 2006-02-28 Chimney structure of natural circulation boiling water reactor Expired - Fee Related JP4500276B2 (en)

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Publication number Priority date Publication date Assignee Title
JP2010175284A (en) * 2009-01-27 2010-08-12 Hitachi-Ge Nuclear Energy Ltd Natural circulation boiling water reactor

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JP5898783B2 (en) 2012-11-16 2016-04-06 日立Ｇｅニュークリア・エナジー株式会社 Natural circulation boiling water reactor and its chimney

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JPH01250893A (en) * 1988-03-31 1989-10-05 Hitachi Ltd Natural circulation boiling light water reactor
JPH04244995A (en) * 1991-01-31 1992-09-01 Toshiba Corp Boiling water reactor
JPH04259894A (en) * 1991-02-14 1992-09-16 Toshiba Corp Natural-circulation type boiling water nuclear reactor
JPH0727051B2 (en) * 1989-03-20 1995-03-29 ゼネラル・エレクトリック・カンパニイ Boiling water reactor system with staggered chimney

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Publication number Priority date Publication date Assignee Title
JPH01250893A (en) * 1988-03-31 1989-10-05 Hitachi Ltd Natural circulation boiling light water reactor
JPH0727051B2 (en) * 1989-03-20 1995-03-29 ゼネラル・エレクトリック・カンパニイ Boiling water reactor system with staggered chimney
JPH04244995A (en) * 1991-01-31 1992-09-01 Toshiba Corp Boiling water reactor
JPH04259894A (en) * 1991-02-14 1992-09-16 Toshiba Corp Natural-circulation type boiling water nuclear reactor

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010175284A (en) * 2009-01-27 2010-08-12 Hitachi-Ge Nuclear Energy Ltd Natural circulation boiling water reactor

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