JP2004061442A - Method of maintaining boiling water reactor and jig for placing temporary in-reactor equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten working time, to cut down costs, and to reduce the dose equivalent, by moving control rod guide tubes, fuel supports and the like only in a reactor in maintaining a reactor pressure vessel and the like. <P>SOLUTION: This method includes: a fuel removal process for hoisting fuel assemblies above the reactor pressure vessel 1 to remove them out of it; a temporarily placing process for hoisting such in-reactor equipment as the fuel supports 5 and the control rod guide tubes 4 and placing it on a top guide 2; a maintenance process for maintaining a reactor after the temporarily placing process; a restoration process for hanging down the in-reactor equipment placed on the top guide 2 to return it to its original position, after the maintenance process; and a fuel loading process after the restoration process. Additionally, the temporary placing process may include a temporary placed jig installation process for placing the temporary placed jig 14 to hung down from above the reactor pressure vessel 1 on the top guide 2, and a process for hoisting the in-reactor equipment, using a temporary placed jig 14 to place it on the top guide 2. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、沸騰水型原子炉の定期点検などの原子炉停止時に、燃料集合体を取り出した後に制御棒、燃料支持金具や制御棒案内管などの炉内機器を移動させて原子炉圧力容器などの点検・保守などの保全を行なう方法およびそのための炉内機器仮置き治具に関する。
【０００２】
【従来の技術】
沸騰水型原子炉の炉内機器である制御棒、燃料支持金具および制御棒案内管は、原子炉圧力容器下部の点検作業実施時などにおいては、点検装置のアクセスを確保するため、一時的に専用治具にて取り外し、使用済み燃料プールに設置された保管用専用ラックに移動して、仮置きし、炉内点検などが終了し、再度炉内に取り付けられるまで一時保管されている。一方、使用済み燃料プールに設置されている保管ラックは、使用済み燃料プール容積等によりラック大きさおよびその保管数が限られる。したがって、取り外した制御棒、燃料支持金具、制御棒案内管が保管数を超える場合はその都度、別途仮置きラックを新規製作、使用済み燃料プールに設置している。
【０００３】
【発明が解決しようとする課題】
しかし、上述のように使用済み燃料プールに仮置きラックを設置する場合、使用済み燃料プール内の設置エリアの空間確保のための機器の移動および整理、据付け場所の吸引清掃、仮置き用ラック製作、据付けに時間やコストがかかる。さらに、炉内から使用済み燃料プールまでの制御棒、燃料支持金具、制御棒案内管などの炉内機器の移動に時間がかかる。その結果、線量当量が増大する。また、炉内機器の炉内から使用済み燃料プールへの移動は使用済み燃料プールゲートが開放されていなければならず、工程的にも制約を受けている。
【０００４】
そこで本発明は、原子炉停止時に原子炉圧力容器などの保全を行なうに当たり、制御棒、燃料支持金具、制御棒案内管などを使用済み燃料プールへ移動させることなく、原子炉内で移動するだけで済ませることにより、移動作業に伴う時間の短縮やコスト低減、線量当量低減を図り、また、使用済み燃料プール仮置きラックの製作や設置に伴う作業時間短縮とコスト低減を図り、さらに、使用済み燃料プールゲート開閉の制約を受けないことによる作業工程の自由度確保を図ることを目的とする。
【０００５】
【課題を解決するための手段】
本発明は上記目的を達成するものであって、請求項１に記載の発明は、原子炉圧力容器と、この原子炉圧力容器内に設置されて複数の開口を有する炉心支持板と、この炉心支持板の上方に設置された上部格子板と、前記炉心支持板の各開口部に配置される複数の燃料支持金具と、この燃料支持金具に載置されて側部を前記上部格子板で支持される複数の燃料集合体と、前記燃料支持金具を貫通して前記燃料集合体の間を上下動自在に配置される複数本の制御棒と、前記炉心支持板の開口を貫通して前記制御棒を案内する制御棒案内管とを具備する沸騰水型原子炉の停止時に当該原子炉を保全する方法において、前記原子炉圧力容器の上部を開放して前記原子炉圧力容器の上部を満水にした状態で、前記複数の燃料集合体の少なくとも一部を前記原子炉圧力容器の上部へ吊り上げて前記原子炉圧力容器の外に取り出す燃料取出し工程と、前記燃料取出し工程の後に、前記燃料支持金具、制御棒および制御棒案内管のうちの少なくとも一部を含む炉内機器を吊り上げて前記上部格子板に設置する仮置き工程と、前記仮置き工程の後に前記原子炉の保全を行なう保全工程と、前記保全工程の後に、前記上部格子板に設置された前記炉内機器を吊り下ろして元の位置に配置する復元工程と、前記復元工程の後に前記複数の燃料集合体を前記燃料支持金具の上に載置する燃料装荷工程と、を有することを特徴とする。
【０００６】
請求項１に記載の発明によれば、原子炉停止時に原子炉圧力容器などの保全を行なうに当たり、炉内機器を上部格子板に仮置きすることにより、炉内機器を使用済み燃料プールまで移送する場合に比べて作業の時間短縮、コスト低減、線量当量低減を実現できる。また、使用済み燃料プール仮置きラック製作にかかる作業の時間短縮、コスト低減もできる。
【０００７】
また、請求項２に記載の発明は、請求項１に記載の沸騰水型原子炉の保全方法において、前記仮置き工程は、前記原子炉圧力容器の上部から吊り下ろした仮置き治具を前記上部格子板に設置する仮置き治具設置工程と、前記仮置き治具設置工程の後に前記炉内機器を吊り上げて前記仮置き治具を用いて前記上部格子板に設置する工程と、を含み、前記復元工程は、前記仮置き治具を用いて前記上部格子板に設置された前記炉内機器を吊り下ろして元の位置に配置する吊り下ろし工程と、前記吊り下ろし工程の後に、前記仮置き治具を前記原子炉圧力容器の上部から吊り上げて前記原子炉圧力容器の外に取り出す仮置き治具取出し工程と、を含むこと、を特徴とする。
【０００８】
請求項２に記載の発明によれば、請求項１に記載の発明による作用・効果が得られるほか、上部格子板に仮置き治具を設置することにより、炉内機器の仮置きや復元を効率的かつ確実に行なうことができる。
【０００９】
また、請求項３に記載の発明は、沸騰水型原子炉の停止時に、原子炉圧力容器内の複数の燃料集合体の少なくとも一部を前記原子炉圧力容器の外に取り出した後に、前記原子炉圧力容器の上部から吊り下ろして前記原子炉圧力容器内の上部格子板に撤去可能に設置される炉内機器仮置き治具であって、前記燃料支持金具、制御棒および制御棒案内管のうちの少なくとも一部を含む炉内機器を吊り上げて前記上部格子板で支持できるように構成されていること、を特徴とする。
【００１０】
請求項３に記載の発明によれば、原子炉停止時に原子炉圧力容器などの保全を行なうに当たり、炉内機器を効率的かつ確実に上部格子板に仮置きし、また復元することができる。これにより、炉内機器を使用済み燃料プールまで移送する場合に比べて作業の時間短縮、コスト低減、線量当量低減を実現できる。また、使用済み燃料プール仮置きラック製作にかかる作業の時間短縮、コスト低減もできる。
【００１１】
また、請求項４に記載の発明は、請求項３に記載の炉内機器仮置き治具において、前記炉内機器を前記上部格子板で支持した状態から、前記炉内機器を吊り上げる際に前記炉内機器仮置き治具が前記上部格子板から離れないように、前記炉内機器仮置き治具を前記上部格子板に仮固定するための炉内機器仮置き治具仮固定手段を有すること、を特徴とする。
【００１２】
請求項４に記載の発明によれば、請求項３に記載の発明による作用・効果が得られるほか、炉内機器を炉内機器仮置き治具から吊り上げる際に炉内機器仮置き治具が上部格子板から離れて炉内機器とともに吊り上げられてしまう事態を防ぐことができる。
【００１３】
また、請求項５に記載の発明は、請求項３または４に記載の炉内機器仮置き治具において、前記燃料支持金具、制御棒および制御棒案内管の各１個が組み合わされた状態で前記上部格子板で支持できるように構成されていること、を特徴とする。
【００１４】
請求項５に記載の発明によれば、請求項３または４に記載の発明による作用・効果が得られるほか、炉内機器である燃料支持金具、制御棒および制御棒案内管を狭いスペースにコンパクトに収納できる。
【００１５】
また、請求項６に記載の発明は、請求項３または４に記載の炉内機器仮置き治具において、前記燃料支持金具または制御棒案内管のいずれか一方のみを前記上部格子板で支持できるように構成されていること、を特徴とする。
【００１６】
請求項６に記載の発明によれば、請求項３または４に記載の発明による作用・効果が得られるほか、燃料支持金具または制御棒案内管だけを仮置きする場合に便利である。
【００１７】
【発明の実施の形態】
以下、本発明に係る沸騰水型原子炉の保全方法および炉内機器仮置き治具の実施の形態を、図面を参照して説明する。ただし、相互に共通もしくは類似の部分には共通の符号を付して、重複説明は適宜省略する。
【００１８】
図１ないし図４を参照して、本発明に係る沸騰水型原子炉における保全方法およびそのための炉内機器仮置き治具の第１の実施の形態を説明する。
図１に示すように、原子炉格納容器２０内に原子炉圧力容器１が配置され、原子炉圧力容器１内には上部格子板２とその下方に炉心支持板３が設置されている。図１は、原子炉を停止して、原子炉の定期点検を行なっている状況を示すものであり、原子炉圧力容器１の蓋（図示せず）は開いており、原子炉圧力容器１の内部およびその上方には水が満たされている。
【００１９】
原子炉格納容器２０に隣接して使用済み燃料プール２２が配置され、使用済み燃料プール２２内に、燃料ラック１３が配置されている。原子炉圧力容器１の上方には燃料交換機１２が配置されている。原子炉運転時に原子炉圧力容器１内にあった燃料集合体は、原子炉の定期点検時に、燃料交換機１２を用いて水中で上方に吊り上げられ、水中で使用済み燃料プール２２に搬送されて燃料ラック１３に置かれる。
【００２０】
図２は、沸騰水型原子炉の運転時における燃料支持金具５周辺の配置状況を示す。炉心支持板３には複数の開口２８が設けられ（図２では１個だけを示す）、各開口２８を制御棒案内管４が貫通している。また、燃料支持金具５が制御棒案内管４の上に載置されている。燃料支持金具５の上面には４個の燃料受け開口２５が設けられ（図２では１個だけ示す）、各燃料受け開口２５の上に燃料集合体（図示せず）が載置される。燃料集合体の上部側面は上部格子板２で横方向に支持される。燃料支持金具５の内部には各燃料受け開口２５に向けた冷却材流路２９が形成され、この流路２９の入口は炉心支持板３の下方にあって、この入口部にオリフィス２６が設けられている。
【００２１】
また、燃料支持金具５には、制御棒６が上下に貫通できる制御棒通路３０が設けられている。この制御棒６は燃料集合体の間を上下方向に動けるようになっている。ただし、図２では制御棒６の図示を省略している。
【００２２】
制御棒案内管４は、炉心支持板３の開口２８を通して原子炉圧力容器１の下部の制御棒駆動機構ハウジング７の上部に挿入されて設置されていて、制御棒６を上下方向に案内するものである。制御棒案内管４の上端で横方向に張り出したラグ板８が炉心支持板３の上面に引っ掛り、さらに炉心支持板３の上面に取り付けられたガイドピン９により水平方向位置が定まるようになっている。燃料支持金具５は燃料支持金具５下部のオリフィス２６部が制御棒案内管４内部に挿入されて搭載され、制御棒案内管４と同様に炉心支持板３上のガイドピン９にて水平方向位置が定まるようになっている。
【００２３】
図１は、定期検査のために、原子炉圧力容器１内にあった燃料集合体を取り出して使用済み燃料プール２２に搬送した後の状態を示しており、上部格子板２は格子内が空いた状態になっている。制御棒６は、原子炉圧力容器１の下方に設けられた制御棒駆動機構１０と切り離された状態で、制御棒案内管４内部に収納されている。炉内点検などによりこれらを取り外す手順は、専用治具１１を燃料交換機１２に取り付け、炉内に吊り下ろし、炉内機器である制御棒６、制御棒案内管４および燃料支持金具５を掴んで吊り上げ、炉内機器仮置き治具１４を用いて、上部格子板２に仮置きする。
【００２４】
図３および図４に示すように、炉内機器仮置き治具１４は、外形がほぼ四角柱状である。炉内機器仮置き治具１４の外側面の途中には段３３が形成され、段３３の上方が下方よりも少し太くなっていて、炉内機器仮置き治具１４を上部格子板２の一つの格子内に挿入するときに段３３の下方だけが挿入され、段３３が上部格子板２の上面に当接してここで荷重を支えられるようになっている。
【００２５】
炉内機器仮置き治具１４には縦方向にほぼ円形の貫通孔が形成され、その貫通孔の中に制御棒案内管４を通すことができるようになっている。そして、制御棒案内管４の上端から外側に張り出したラグ板８が炉内機器仮置き治具１４の上面と当接し、ここで制御棒案内管４の荷重が支持される。また、炉内機器仮置き治具１４の上面に位置決め用のガイドピン１５が上向きに突出して設けられている。さらに、当該治具１４を設置する格子の下部同位置に設置している炉内機器との干渉を回避するため、上部格子板２の板上部から適切な高さを確保している。
【００２６】
一時的に専用治具１１にて取り外された制御棒６、燃料支持金具５および制御棒案内管４は炉内機器仮置き治具１４の貫通孔に上部より挿入され、制御棒案内管４のラグ板８が引っ掛ることにより仮置き状態が完成する。
以上説明した制御棒案内管４などの炉内機器を炉内機器仮置き治具１４に仮置きした後に、原子炉圧力容器１の下部などの保全を行なう。
【００２７】
その後の復元作業は上記の仮置き作業の逆に行なう。すなわち、初めに、専用治具１１と燃料交換機１２を用いて、炉内機器仮置き治具１４から制御棒案内管４などの炉内機器を取り外して吊り下ろし、元の位置に取り付ける。その後、専用治具１１と燃料交換機１２を用いて、上部格子板２から炉内機器仮置き治具１４を吊り上げて原子炉外に取り出す。その後、燃料交換機１２を用いて、燃料集合体を原子炉外から搬入し、燃料支持金具５の上に載置する。なお、これらの一連の作業は、原子炉圧力容器１の内部およびその上方に水を満たした状態で行なう。
【００２８】
以上説明した第１の実施の形態によれば、使用済み燃料プール２２内に仮置きラックを製作したり設置したりする作業をなくすまたは減らすことができ、コスト低減、被曝低減を実現できる。また、制御棒６、燃料支持金具５、制御棒案内管４を炉内から使用済み燃料プール２２へ移動させずに済むことから、移動時間短縮、および、使用済み燃料プールゲート開閉の制約を受けないことによる作業工程に対する自由度確保ができ、実用的に極めて有効である。
【００２９】
なお、制御棒案内管４などの炉内機器は必ずしも全てを炉内機器仮置き治具１４に仮置きする必要はなく、多数ある制御棒案内管４などの炉内機器のうちの一部を炉内機器仮置き治具１４に仮置きし、残りを使用済み燃料プール２２に移送するようにしてもよい。この場合でも、使用済み燃料プール２２に移送する制御棒案内管４などの炉内機器の量を減らすことができる。
【００３０】
また、上記説明では炉内機器仮置き治具１４を用いることとしたが、変形例として、上部格子板２自体に炉内機器仮置き構造を持たせることにより、炉内機器仮置き治具１４を省略することも可能である。
【００３１】
次に、図５および図６を参照して、本発明に係る炉内機器仮置き治具の第２、第３の実施の形態を説明する。図５および図６において、炉内機器仮置き治具１４は、それぞれ、制御棒案内管４だけ、または燃料支持金具５だけを仮置きできる構造になっている。その他の構造は第１の実施の形態の場合と同様である。これらの炉内機器仮置き治具１４は、第１の実施の形態と同様に上部格子板２上に仮置きされ、その炉内機器仮置き治具１４に、それぞれ、制御棒案内管４だけ、または燃料支持金具５だけを仮置きする。
【００３２】
次に、図７は本発明に係る炉内機器仮置き治具の第４の実施の形態を示すもので、ここでは、炉内機器仮置き治具１４は、第１の実施の形態における炉内機器仮置き治具１４を一要素としてこれを縦横２個ずつ合計４個水平に並べて一体にしたものである。各要素は別々に作ってこれらを任意に互いに着脱できるようにしてもよいし、初めから全体で一体のものとして作ってもよい。また、各要素の並べ方は上部格子板２に適合するものであれば、２行２列の配列に限らず、また全体で何個の要素を並べたものとしてもよい。また、各要素は、第１の実施の形態のように制御棒案内管４、燃料支持金具５および制御棒６を仮置きできるものでもよいし、第２または第３の実施の形態のように、制御棒案内管４または燃料支持金具５だけを仮置きできるものでもよい。
【００３３】
次に、図８および図９は、本発明に係る炉内機器仮置き治具の第５の実施の形態を示すものである。この炉内機器仮置き治具１４には、その上部にあって上下方向に動ける着座ピン１６と、下部に突出し外側に張出し可能な１対の脱落防止つば１７と、これらの脱落防止つば１７を外側に向けて押すばね１８が設けられている。
【００３４】
着座ピン１６を下方に押していないときは、図８（ａ）および図９（ａ）に示すように着座ピン１６の上端が上方に突出しており、ばね１８によって脱落防止つば１７が外側に張り出している。また、着座ピン１６を下方に押し込むと、図８（ｂ）および図９（ｂ）に示すように脱落防止つば１７がばね１８の力に抗して内側に押される。
【００３５】
したがって、炉内機器仮置き治具１４を上部格子板２に取り付けるとき、および、これを取り外すときには、図８（ｂ）および図９（ｂ）に示すように着座ピン１６を下方に押し込むことによって脱落防止つば１７を内側に引き込むことができる。また、炉内機器仮置き治具１４を上部格子板２に取り付けた後には、着座ピン１６を押すのをやめれば、ばね１８の力で図８（ａ）および図９（ａ）に示すように脱落防止つば１７が外側に広がる。
【００３６】
これにより、炉内機器仮置き治具１４が上部格子板２から不用意に外れることを防止できる。すなわち、炉内機器仮置き治具１４に制御棒案内管４などを仮置きしたり、これを炉内機器仮置き治具１４から取り外すときに、制御棒案内管４などとともに炉内機器仮置き治具１４が上部格子板２から外れることを防止できる。
なお、図９（ａ）、（ｂ）に示すガイドピン１５は、図３などに示すガイドピン１５と同様のものであるが、図８では、ガイドピン１５の図示を省略している。
【００３７】
【発明の効果】
以上説明したように、本発明によれば、原子炉停止時に原子炉圧力容器などの保全を行なうに当たり、炉内機器を上部格子板に仮置きすることにより、炉内機器を使用済み燃料プールまで移送する場合に比べて作業の時間短縮、コスト低減、線量当量低減を実現できる。また、使用済み燃料プール仮置きラック製作にかかる作業の時間短縮、コスト低減もできる。
【図面の簡単な説明】
【図１】本発明に係る沸騰水型原子炉の保全方法の第１の実施の形態において、制御棒、燃料支持金具および制御棒案内管が上部格子板に仮置きされた状態を示す原子炉全体の縦断面図。
【図２】沸騰水型原子炉の運転時における燃料支持金具などの設置状況を示す部分立断面図。
【図３】図１における炉内機器仮置き治具の周辺部を拡大して示す縦断面図。
【図４】図３の上部を示す斜視図。
【図５】本発明に係る炉内機器仮置き治具の第２の実施の形態の周辺部を含む斜視図。
【図６】本発明に係る炉内機器仮置き治具の第３の実施の形態の周辺部を含む斜視図。
【図７】本発明に係る炉内機器仮置き治具の第４の実施の形態の周辺部を含む斜視図。
【図８】本発明に係る炉内機器仮置き治具の第５の実施の形態の周辺部を含む縦断面図であって、（ａ）は脱落防止つばが拡張して上部格子板と係合した状況を示し、（ｂ）は脱落防止つばと上部格子板との係合が解除された状況を示す。
【図９】図８の炉内機器仮置き治具の周辺部を含む斜視図であって、（ａ）、（ｂ）はそれぞれ、図８の（ａ）、（ｂ）に対応する状況を示す。
【符号の説明】
１…原子炉圧力容器、２…上部格子板、３…炉心支持板、４…制御棒案内管、５…燃料支持金具、６…制御棒、７…制御棒駆動機構ハウジング、８…ラグ板、９…ガイドピン、１０…制御棒駆動機構、１１…専用治具、１２…燃料交換機、１３…燃料ラック、１４…炉内機器仮置き治具、１５…ガイドピン、１６…着座ピン、１７…脱落防止つば、１８…ばね、２０…原子炉格納容器、２２…使用済み燃料プール、２５…燃料受け開口、２６…炉心入口オリフィス、２８…炉心支持板開口、２９…流路、３０…制御棒通路、３３…段。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reactor pressure vessel for controlling a reactor rod such as a control rod, a fuel support bracket and a control rod guide tube after removing a fuel assembly during a reactor shutdown such as a periodic inspection of a boiling water reactor. The present invention relates to a method for performing maintenance such as inspection and maintenance, and a jig for temporarily placing equipment in the furnace.
[0002]
[Prior art]
The control rods, fuel support fittings, and control rod guide tubes, which are internal components of a boiling water reactor, are temporarily installed to ensure access to inspection equipment, such as when inspecting the lower part of the reactor pressure vessel. It is removed with a dedicated jig, moved to a dedicated storage rack installed in the spent fuel pool, temporarily placed, inspected inside the furnace, etc., and temporarily stored until it is installed in the furnace again. On the other hand, the storage rack installed in the spent fuel pool has a limited size and the number of stored racks depending on the volume of the spent fuel pool and the like. Therefore, whenever the number of removed control rods, fuel support brackets, and control rod guide tubes exceeds the number to be stored, a temporary storage rack is separately manufactured and installed in the used fuel pool.
[0003]
[Problems to be solved by the invention]
However, when installing a temporary storage rack in the spent fuel pool as described above, moving and organizing equipment to secure a space for the installation area in the spent fuel pool, suction cleaning of the installation location, and manufacturing a temporary storage rack It takes time and cost for installation. Further, it takes time to move the in-furnace equipment such as control rods, fuel support fittings, and control rod guide tubes from the furnace to the spent fuel pool. As a result, the dose equivalent increases. In addition, the movement of the in-furnace equipment from the inside of the furnace to the spent fuel pool requires that the spent fuel pool gate be open, which imposes restrictions on the process.
[0004]
Therefore, in the present invention, when the reactor pressure vessel and the like are to be maintained when the reactor is stopped, the control rods, the fuel support fittings, the control rod guide tubes, etc. are moved within the reactor without moving them to the spent fuel pool. To reduce the time and cost associated with moving work, reduce the dose equivalent, and reduce the working time and cost associated with the production and installation of the spent fuel pool temporary storage rack. The objective is to ensure the flexibility of the work process by not being restricted by the opening and closing of the fuel pool gate.
[0005]
[Means for Solving the Problems]
The present invention achieves the above object, and the invention according to claim 1 includes a reactor pressure vessel, a core support plate provided in the reactor pressure vessel and having a plurality of openings, and a reactor core. An upper grid plate installed above the support plate, a plurality of fuel support fittings arranged at each opening of the core support plate, and a side portion mounted on the fuel support fitting to support a side portion with the upper grid plate. A plurality of fuel assemblies, a plurality of control rods penetrating through the fuel support fittings and disposed vertically movably between the fuel assemblies, and the control through an opening in the core support plate. A method for maintaining a nuclear reactor when a boiling water reactor is shut down, comprising a control rod guide tube for guiding a rod, wherein the upper part of the reactor pressure vessel is opened and the upper part of the reactor pressure vessel is filled with water. With at least a portion of the plurality of fuel assemblies A fuel take-out step that is lifted to the upper part of the reactor pressure vessel and taken out of the reactor pressure vessel; and, after the fuel take-out step, includes at least a part of the fuel support bracket, the control rod, and the control rod guide tube. A temporary placing step of lifting the furnace equipment and placing it on the upper lattice plate, a maintenance step of maintaining the nuclear reactor after the temporary placing step, and after the maintenance step, A restoring step of suspending the in-furnace equipment and placing it in its original position, and a fuel loading step of placing the plurality of fuel assemblies on the fuel support after the restoring step. I do.
[0006]
According to the first aspect of the present invention, when the reactor pressure vessel and the like are maintained when the reactor is stopped, the reactor internal equipment is temporarily placed on the upper lattice plate to transfer the reactor internal equipment to the spent fuel pool. It is possible to shorten the operation time, reduce the cost, and reduce the dose equivalent as compared with the case of performing the operation. In addition, it is possible to reduce the time and cost of the work for manufacturing the spent fuel pool temporary storage rack.
[0007]
The invention according to claim 2 is the maintenance method for a boiling water reactor according to claim 1, wherein the temporary placing step includes the step of suspending a temporary placing jig suspended from an upper part of the reactor pressure vessel. A temporary placing jig installation step of installing on the upper lattice plate, and a step of lifting the in-furnace equipment after the temporary placing jig installing step and installing the same on the upper lattice plate using the temporary placing jig. The restoring step comprises: suspending the in-furnace equipment installed on the upper lattice plate using the temporary placing jig, suspending the in-furnace equipment, and arranging the equipment at an original position, and after the suspending step, A temporary jig removal step of lifting the storage jig from above the reactor pressure vessel and taking it out of the reactor pressure vessel.
[0008]
According to the second aspect of the present invention, the operation and effect of the first aspect of the present invention can be obtained, and the temporary placing and restoring of the furnace equipment can be performed by installing the temporary placing jig on the upper lattice plate. It can be performed efficiently and reliably.
[0009]
Further, the invention according to claim 3 is characterized in that, when the boiling water reactor is stopped, at least a part of the plurality of fuel assemblies in the reactor pressure vessel is taken out of the reactor pressure vessel, A jig for temporarily placing in-reactor equipment, which is hung from the upper part of the reactor pressure vessel and is removably installed on an upper lattice plate in the reactor pressure vessel, wherein the fuel support bracket, the control rod, and the control rod guide tube are provided. The apparatus is characterized in that furnace equipment including at least a part thereof is lifted and supported by the upper lattice plate.
[0010]
According to the third aspect of the present invention, in performing maintenance of the reactor pressure vessel or the like when the reactor is stopped, the in-reactor equipment can be temporarily and reliably temporarily placed on the upper lattice plate and restored. As a result, the operation time, cost, and dose equivalent can be reduced as compared with the case where the furnace equipment is transferred to the spent fuel pool. In addition, it is possible to reduce the time and cost of the work for manufacturing the spent fuel pool temporary storage rack.
[0011]
Further, the invention according to claim 4 is the jig for temporarily placing the in-furnace equipment in the furnace according to claim 3, wherein the in-furnace equipment is lifted from a state in which the in-furnace equipment is supported by the upper lattice plate. In order to prevent the in-furnace equipment temporary storage jig from separating from the upper lattice plate, the in-furnace equipment temporary storage jig temporary fixing means for temporarily fixing the in-furnace equipment temporary storage jig to the upper lattice plate is provided. , Is characterized.
[0012]
According to the invention set forth in claim 4, the operation and effect of the invention set forth in claim 3 are obtained, and when the furnace equipment is lifted from the furnace equipment temporary storage jig, the furnace equipment temporary storage jig is used. It is possible to prevent a situation in which the apparatus is lifted away from the upper lattice plate together with the furnace equipment.
[0013]
According to a fifth aspect of the present invention, in the jig for temporarily placing in-furnace equipment according to the third or fourth aspect, the fuel support bracket, the control rod, and the control rod guide tube are each combined. It is configured to be supported by the upper lattice plate.
[0014]
According to the fifth aspect of the present invention, the operation and effect of the third or fourth aspect of the present invention can be obtained, and the fuel support fitting, the control rod, and the control rod guide tube, which are furnace equipment, can be compactly arranged in a small space. Can be stored.
[0015]
According to a sixth aspect of the present invention, in the furnace temporary storage jig according to the third or fourth aspect, only one of the fuel support bracket and the control rod guide tube can be supported by the upper grid plate. It is characterized by being constituted as follows.
[0016]
According to the invention described in claim 6, the function and effect of the invention described in claim 3 or 4 can be obtained, and it is convenient when only the fuel support bracket or the control rod guide tube is temporarily placed.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a method for maintaining a boiling water reactor and a jig for temporarily placing equipment in a reactor according to the present invention will be described with reference to the drawings. However, common or similar parts are denoted by the same reference numerals, and redundant description will be omitted as appropriate.
[0018]
With reference to FIGS. 1 to 4, a first embodiment of a maintenance method for a boiling water reactor and a jig for temporarily placing in-furnace equipment therefor according to the present invention will be described.
As shown in FIG. 1, a reactor pressure vessel 1 is disposed in a reactor containment vessel 20, and an upper lattice plate 2 and a core support plate 3 below the upper lattice plate 2 are installed in the reactor pressure vessel 1. FIG. 1 shows a situation in which the reactor is shut down and a periodic inspection of the reactor is being performed. The lid (not shown) of the reactor pressure vessel 1 is open, and the reactor pressure vessel 1 is closed. The interior and above it are filled with water.
[0019]
A spent fuel pool 22 is disposed adjacent to the containment vessel 20, and a fuel rack 13 is disposed in the spent fuel pool 22. Above the reactor pressure vessel 1, a refueling machine 12 is arranged. The fuel assemblies in the reactor pressure vessel 1 during the operation of the reactor are lifted underwater using the refueling machine 12 at the time of periodic inspection of the reactor, transported underwater to the spent fuel pool 22, and transported to the spent fuel pool 22. It is placed on the rack 13.
[0020]
FIG. 2 shows an arrangement around the fuel support 5 during operation of the boiling water reactor. A plurality of openings 28 are provided in the core support plate 3 (only one is shown in FIG. 2), and the control rod guide tube 4 penetrates each opening 28. Further, a fuel support fitting 5 is mounted on the control rod guide tube 4. Four fuel receiving openings 25 are provided on the upper surface of the fuel support 5 (only one fuel receiving opening 25 is shown in FIG. 2), and a fuel assembly (not shown) is mounted on each fuel receiving opening 25. The upper side surface of the fuel assembly is supported laterally by the upper grid plate 2. A coolant channel 29 is formed inside the fuel support fitting 5 toward each fuel receiving opening 25. The inlet of the channel 29 is below the core support plate 3, and an orifice 26 is provided at the inlet. Have been.
[0021]
Further, the fuel support fitting 5 is provided with a control rod passage 30 through which the control rod 6 can pass vertically. The control rod 6 can move vertically between the fuel assemblies. However, illustration of the control rod 6 is omitted in FIG.
[0022]
The control rod guide tube 4 is inserted and installed in the upper part of the control rod drive mechanism housing 7 below the reactor pressure vessel 1 through the opening 28 of the core support plate 3 and guides the control rod 6 in the vertical direction. It is. A lug plate 8 projecting laterally at the upper end of the control rod guide tube 4 is hooked on the upper surface of the core support plate 3, and the horizontal position is determined by guide pins 9 attached to the upper surface of the core support plate 3. ing. The fuel support 5 is mounted with the orifice 26 at the lower portion of the fuel support 5 inserted into the control rod guide tube 4, and similarly to the control rod guide tube 4, is positioned horizontally by the guide pins 9 on the core support plate 3. Is to be determined.
[0023]
FIG. 1 shows a state after the fuel assembly in the reactor pressure vessel 1 is taken out and transported to the spent fuel pool 22 for a periodic inspection, and the upper grid plate 2 is empty in the grid. It is in a state of being left. The control rod 6 is housed inside the control rod guide tube 4 in a state separated from the control rod drive mechanism 10 provided below the reactor pressure vessel 1. In order to remove them by furnace inspection, etc., the special jig 11 is attached to the fuel exchanger 12, suspended in the furnace, and the control rod 6, the control rod guide tube 4, and the fuel support bracket 5, which are in-furnace equipment, are grasped. It is suspended and temporarily placed on the upper lattice plate 2 by using the in-furnace equipment temporary placement jig 14.
[0024]
As shown in FIG. 3 and FIG. 4, the in-furnace equipment temporary storage jig 14 has a substantially quadrangular prism shape. A step 33 is formed in the middle of the outer surface of the in-furnace equipment temporary storage jig 14, and the upper part of the step 33 is slightly thicker than the lower part. When inserted into one grid, only the lower part of the step 33 is inserted, and the step 33 contacts the upper surface of the upper grid plate 2 so that the load can be supported here.
[0025]
A substantially circular through-hole is formed in the furnace equipment temporary storage jig 14 in the vertical direction, and the control rod guide tube 4 can be passed through the through-hole. Then, the lug plate 8 projecting outward from the upper end of the control rod guide tube 4 comes into contact with the upper surface of the in-furnace equipment temporary placing jig 14, where the load of the control rod guide tube 4 is supported. In addition, guide pins 15 for positioning are provided on the upper surface of the in-furnace equipment temporary storage jig 14 so as to protrude upward. Furthermore, in order to avoid interference with furnace equipment installed at the same position in the lower part of the grid on which the jig 14 is installed, an appropriate height from the upper part of the upper grid plate 2 is secured.
[0026]
The control rod 6, the fuel support 5, and the control rod guide tube 4 temporarily removed by the special jig 11 are inserted into the through holes of the in-furnace equipment temporary placement jig 14 from above, and the control rod guide tube 4 The temporary placement state is completed by the lug plate 8 being hooked.
After the in-furnace equipment such as the control rod guide tube 4 described above is temporarily placed on the in-furnace equipment temporary holding jig 14, the lower part of the reactor pressure vessel 1 is maintained.
[0027]
Subsequent restoration work is performed in the reverse of the above temporary placement work. That is, first, the in-furnace equipment such as the control rod guide tube 4 is detached from the in-furnace equipment temporary placing jig 14 using the dedicated jig 11 and the fuel exchanger 12, suspended and attached to the original position. Thereafter, using the special jig 11 and the fuel exchanger 12, the in-furnace equipment temporary holding jig 14 is lifted from the upper lattice plate 2 and taken out of the reactor. Thereafter, the fuel assembly is carried in from the outside of the nuclear reactor using the refueling machine 12 and is mounted on the fuel support 5. These series of operations are performed in a state where the inside of the reactor pressure vessel 1 and its upper part are filled with water.
[0028]
According to the first embodiment described above, it is possible to eliminate or reduce the work of manufacturing and installing a temporary storage rack in the spent fuel pool 22, thereby realizing cost reduction and exposure reduction. Further, since the control rod 6, the fuel support fitting 5, and the control rod guide tube 4 do not have to be moved from the furnace to the spent fuel pool 22, the movement time is shortened and the opening and closing of the spent fuel pool gate is restricted. The degree of freedom for the work process can be ensured due to the absence, and it is extremely effective practically.
[0029]
It is not always necessary to temporarily place all of the in-furnace equipment such as the control rod guide tube 4 on the in-furnace equipment temporary placement jig 14. It is also possible to temporarily place the in-furnace equipment temporary jig 14 and transfer the rest to the spent fuel pool 22. Also in this case, the amount of in-furnace equipment such as the control rod guide tube 4 to be transferred to the spent fuel pool 22 can be reduced.
[0030]
In the above description, the in-furnace equipment temporary storage jig 14 is used. However, as a modification, the in-furnace equipment temporary storage jig 14 is provided by providing the in-furnace equipment temporary storage structure to the upper lattice plate 2 itself. May be omitted.
[0031]
Next, second and third embodiments of the in-furnace equipment temporary storage jig according to the present invention will be described with reference to FIGS. 5 and 6, the in-furnace equipment temporary storage jig 14 has a structure in which only the control rod guide tube 4 or only the fuel support metal 5 can be temporarily installed. Other structures are the same as those of the first embodiment. These in-furnace equipment temporary placing jigs 14 are temporarily placed on the upper lattice plate 2 in the same manner as in the first embodiment. Alternatively, only the fuel support 5 is temporarily placed.
[0032]
Next, FIG. 7 shows a fourth embodiment of the in-furnace equipment temporary storage jig according to the present invention. In this case, the in-furnace equipment temporary storage jig 14 is a furnace in the first embodiment. The internal device temporary placement jig 14 is one element, and two of them are arranged horizontally and vertically, two in total, and integrated. Each element may be made separately so that they can be arbitrarily attached to and detached from each other, or may be made integrally as a whole from the beginning. In addition, the arrangement of the elements is not limited to the arrangement of 2 rows and 2 columns as long as the arrangement is suitable for the upper lattice plate 2, and any number of elements may be arranged as a whole. In addition, each element may be such that the control rod guide tube 4, the fuel support 5 and the control rod 6 can be temporarily placed as in the first embodiment, or as in the second or third embodiment. Alternatively, only the control rod guide tube 4 or the fuel support 5 may be temporarily placed.
[0033]
Next, FIGS. 8 and 9 show a fifth embodiment of the in-furnace equipment temporary storage jig according to the present invention. The in-furnace equipment temporary placing jig 14 includes a seating pin 16 at the upper part thereof, which can move vertically, a pair of drop-off preventing flanges 17 projecting downward and projecting outward, and these drop-off preventing flanges 17. A spring 18 for pushing outward is provided.
[0034]
When the seat pin 16 is not pushed downward, the upper end of the seat pin 16 projects upward as shown in FIGS. 8A and 9A, and the fall-preventing collar 17 projects outward by the spring 18. I have. When the seat pin 16 is pushed downward, the fall-off prevention collar 17 is pushed inward against the force of the spring 18 as shown in FIGS. 8B and 9B.
[0035]
Accordingly, when the in-furnace equipment temporary placing jig 14 is attached to the upper lattice plate 2 and when the jig is removed, the seating pin 16 is pushed downward as shown in FIGS. 8B and 9B. The fall prevention collar 17 can be pulled inward. Further, after the temporary placement jig 14 for the furnace is attached to the upper lattice plate 2, if the pressing of the seating pin 16 is stopped, the force of the spring 18 causes the force as shown in FIGS. The fall prevention collar 17 spreads outward.
[0036]
This can prevent the in-furnace equipment temporary storage jig 14 from being accidentally detached from the upper lattice plate 2. That is, when the control rod guide tube 4 and the like are temporarily placed on the in-furnace device temporary placing jig 14 and when the control rod guide tube 4 and the like are removed from the in-furnace device temporary placing jig 14, the in-furnace device temporary placing together with the control rod guide tube 4 and the like are performed. The jig 14 can be prevented from coming off the upper lattice plate 2.
The guide pins 15 shown in FIGS. 9A and 9B are similar to the guide pins 15 shown in FIG. 3 and the like, but the guide pins 15 are not shown in FIG.
[0037]
【The invention's effect】
As described above, according to the present invention, in performing maintenance of a reactor pressure vessel and the like when the reactor is shut down, the in-core equipment is temporarily placed on the upper lattice plate to allow the in-core equipment to reach the spent fuel pool. The work time, cost, and dose equivalent can be reduced as compared with the case of transfer. In addition, it is possible to reduce the time and cost of the work for manufacturing the spent fuel pool temporary storage rack.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of a boiling water reactor maintenance method according to the present invention, in which a control rod, a fuel support bracket, and a control rod guide tube are temporarily placed on an upper lattice plate. FIG.
FIG. 2 is a partial vertical sectional view showing the installation state of a fuel support fitting and the like during operation of the boiling water reactor.
FIG. 3 is an enlarged longitudinal sectional view showing a peripheral portion of the in-furnace equipment temporary placing jig in FIG. 1;
FIG. 4 is a perspective view showing the upper part of FIG. 3;
FIG. 5 is a perspective view including a peripheral portion of a second embodiment of the in-furnace equipment temporary storage jig according to the present invention.
FIG. 6 is a perspective view including a peripheral portion of a third embodiment of the in-furnace equipment temporary storage jig according to the present invention.
FIG. 7 is a perspective view including a peripheral portion of a fourth embodiment of the in-furnace equipment temporary storage jig according to the present invention.
FIG. 8 is a longitudinal sectional view including a peripheral portion of a fifth embodiment of a temporary storage device for in-furnace equipment according to the present invention, wherein FIG. (B) shows a state in which the engagement between the fall-prevention collar and the upper lattice plate has been released.
9 is a perspective view including a peripheral portion of the in-furnace equipment temporary storage jig of FIG. 8, wherein (a) and (b) show situations corresponding to (a) and (b) of FIG. 8, respectively. Show.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Upper lattice plate, 3 ... Core support plate, 4 ... Control rod guide tube, 5 ... Fuel support bracket, 6 ... Control rod, 7 ... Control rod drive mechanism housing, 8 ... Lug plate, Reference numeral 9: guide pin, 10: control rod drive mechanism, 11: dedicated jig, 12: refueling machine, 13: fuel rack, 14: temporary installation jig in the furnace, 15: guide pin, 16: seating pin, 17: Fall prevention collar, 18: spring, 20: reactor containment vessel, 22: spent fuel pool, 25: fuel receiving opening, 26: core inlet orifice, 28: core support plate opening, 29: flow path, 30: control rod Passage, 33 ... steps.

Claims (6)

原子炉圧力容器と、この原子炉圧力容器内に設置されて複数の開口を有する炉心支持板と、この炉心支持板の上方に設置された上部格子板と、前記炉心支持板の各開口部に配置される複数の燃料支持金具と、この燃料支持金具に載置されて側部を前記上部格子板で支持される複数の燃料集合体と、前記燃料支持金具を貫通して前記燃料集合体の間を上下動自在に配置される複数本の制御棒と、前記炉心支持板の開口を貫通して前記制御棒を案内する制御棒案内管とを具備する沸騰水型原子炉の停止時に当該原子炉を保全する方法において、
前記原子炉圧力容器の上部を開放して前記原子炉圧力容器の上部を満水にした状態で、前記複数の燃料集合体の少なくとも一部を前記原子炉圧力容器の上部へ吊り上げて前記原子炉圧力容器の外に取り出す燃料取出し工程と、
前記燃料取出し工程の後に、前記燃料支持金具、制御棒および制御棒案内管のうちの少なくとも一部を含む炉内機器を吊り上げて前記上部格子板に設置する仮置き工程と、
前記仮置き工程の後に前記原子炉の保全を行なう保全工程と、
前記保全工程の後に、前記上部格子板に設置された前記炉内機器を吊り下ろして元の位置に配置する復元工程と、
前記復元工程の後に前記複数の燃料集合体を前記燃料支持金具の上に載置する燃料装荷工程と、
を有することを特徴とする沸騰水型原子炉の保全方法。A reactor pressure vessel, a core support plate installed in the reactor pressure vessel and having a plurality of openings, an upper lattice plate installed above the core support plate, and each opening of the core support plate. A plurality of fuel support members to be arranged, a plurality of fuel assemblies placed on the fuel support members and having side portions supported by the upper lattice plate, and a plurality of fuel assemblies penetrating through the fuel support members. When a boiling water reactor is stopped, the control rod includes a plurality of control rods arranged to be vertically movable between the control rods and a control rod guide tube for guiding the control rods through an opening of the core support plate. In the method of preserving the furnace,
With the upper part of the reactor pressure vessel opened and the upper part of the reactor pressure vessel filled with water, at least a part of the plurality of fuel assemblies is lifted to the upper part of the reactor pressure vessel to raise the reactor pressure. A fuel removal process to be taken out of the container,
After the fuel take-out step, a temporary placement step of lifting the in-furnace equipment including at least a part of the fuel support bracket, control rods, and control rod guide tubes and placing the equipment on the upper lattice plate,
A maintenance step of maintaining the reactor after the temporary placement step,
After the maintenance step, a restoration step of hanging down the in-furnace equipment installed on the upper lattice plate and arranging the equipment at the original position,
A fuel loading step of placing the plurality of fuel assemblies on the fuel support after the restoration step;
A method for maintaining a boiling water reactor, comprising: 請求項１に記載の沸騰水型原子炉の保全方法において、
前記仮置き工程は、前記原子炉圧力容器の上部から吊り下ろした仮置き治具を前記上部格子板に設置する仮置き治具設置工程と、前記仮置き治具設置工程の後に前記炉内機器を吊り上げて前記仮置き治具を用いて前記上部格子板に設置する工程と、を含み、
前記復元工程は、前記仮置き治具を用いて前記上部格子板に設置された前記炉内機器を吊り下ろして元の位置に配置する吊り下ろし工程と、前記吊り下ろし工程の後に、前記仮置き治具を前記原子炉圧力容器の上部から吊り上げて前記原子炉圧力容器の外に取り出す仮置き治具取出し工程と、を含むこと、
を特徴とする沸騰水型原子炉の保全方法。The method for maintaining a boiling water reactor according to claim 1,
The temporary placing step is a temporary placing jig setting step of placing a temporary placing jig suspended from an upper part of the reactor pressure vessel on the upper lattice plate, and the in-furnace equipment after the temporary placing jig setting step. Lifting and installing the upper grid plate using the temporary placing jig,
The restoring step is a hanging step of hanging down the in-furnace equipment installed on the upper lattice plate using the temporary placing jig and disposing the equipment in an original position, and after the hanging down step, the temporary placing is performed. Temporarily removing the jig from the upper part of the reactor pressure vessel and taking it out of the reactor pressure vessel.
A method for maintaining a boiling water reactor. 沸騰水型原子炉の停止時に、原子炉圧力容器内の複数の燃料集合体の少なくとも一部を前記原子炉圧力容器の外に取り出した後に、前記原子炉圧力容器の上部から吊り下ろして前記原子炉圧力容器内の上部格子板に撤去可能に設置される炉内機器仮置き治具であって、
前記燃料支持金具、制御棒および制御棒案内管のうちの少なくとも一部を含む炉内機器を吊り上げて前記上部格子板で支持できるように構成されていること、
を特徴とする炉内機器仮置き治具。At the time of shutdown of the boiling water reactor, at least a part of the plurality of fuel assemblies in the reactor pressure vessel is taken out of the reactor pressure vessel, and the fuel assemblies are suspended from the upper part of the reactor pressure vessel. Furnace equipment temporary storage jig installed removably on the upper lattice plate in the furnace pressure vessel,
The fuel support fitting, the control rods and the control rods are configured to be able to be supported by the upper grid plate by lifting the in-furnace equipment including at least a part of the control rod guide tube,
Furnace temporary storage jig characterized by the following. 請求項３に記載の炉内機器仮置き治具において、前記炉内機器を前記上部格子板で支持した状態から、前記炉内機器を吊り上げる際に前記炉内機器仮置き治具が前記上部格子板から離れないように、前記炉内機器仮置き治具を前記上部格子板に仮固定するための炉内機器仮置き治具仮固定手段を有すること、を特徴とする炉内機器仮置き治具。4. The jig for temporarily placing in-furnace equipment according to claim 3, wherein the jig for temporarily placing in-furnace equipment includes the upper grid when lifting the in-furnace equipment from a state in which the in-furnace equipment is supported by the upper lattice plate. 5. Furnace temporary storage jig temporary fixing means for temporarily fixing the in-furnace equipment temporary storage jig to the upper lattice plate so as not to separate from the plate. Utensils. 請求項３または４に記載の炉内機器仮置き治具において、前記燃料支持金具、制御棒および制御棒案内管の各１個が組み合わされた状態で前記上部格子板で支持できるように構成されていること、を特徴とする炉内機器仮置き治具。5. The jig for temporarily placing in-furnace equipment according to claim 3, wherein the fuel support bracket, the control rod, and the control rod guide tube are each supported by the upper lattice plate in a combined state. A jig for temporarily placing equipment in the furnace. 請求項３または４に記載の炉内機器仮置き治具において、前記燃料支持金具または制御棒案内管のいずれか一方のみを前記上部格子板で支持できるように構成されていること、を特徴とする炉内機器仮置き治具。5. The jig for temporarily placing in-furnace equipment according to claim 3, wherein only one of the fuel support bracket and the control rod guide tube is configured to be supported by the upper lattice plate. 6. Furnace equipment temporary storage jig.

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