JP2004125714A - Sealing structure of radioactive substance containment vessel - Google Patents

Sealing structure of radioactive substance containment vessel Download PDF

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JP2004125714A
JP2004125714A JP2002293099A JP2002293099A JP2004125714A JP 2004125714 A JP2004125714 A JP 2004125714A JP 2002293099 A JP2002293099 A JP 2002293099A JP 2002293099 A JP2002293099 A JP 2002293099A JP 2004125714 A JP2004125714 A JP 2004125714A
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lid
seal member
trunk
storage container
radioactive substance
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JP3848913B2 (en
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Masanari Osono
大園　勝成
Kazuo Asada
浅田　和雄
Shinji Okame
大亀　信二
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Mitsubishi Heavy Industries Ltd
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Mitsubishi Heavy Industries Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing structure of a radioactive substance containment vessel, improving reliability of the sealing of the radioactive substance containment vessel, and capable of maintaining the reliability of the sealing of the radioactive substance containment vessel when the radioactive substance containment vessel falls or collides. <P>SOLUTION: This sealing structure of the radioactive substance containment vessel 1 has: a barrel body 2 storing radioactive substance R at least inside a cavity 2b, provided with neutron shields 6 around the cavity 2b; a lid part 3 installed to the barrel body 2; and a sealing means (gaskets 10a, 10b) sealing the barrel body 2 and the lid part 3. The lid part 3 has a primary lid 7 installed inside an opening part 2a, and a secondary lid 8 installed to the outside of the primary lid 7. At least a seal member 12 different from the sealing means having flexibility in the radial direction of the barrel body 2 is installed between the barrel body 2 and the primary lid 7 by welding. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、燃焼を終えたリサイクル燃料集合体を収納する放射性物質格納容器の密閉構造に関し、更に詳しくは、密閉手段とこの密閉手段とは異なるシール部材により構成される放射性物質格納容器の密閉構造に関する。
【０００２】
【従来の技術】
核燃料サイクルの周期にあって燃焼を終えた核燃料集合体を、リサイクル燃料集合体という。リサイクル燃料集合体は、ＦＰなど高放射性物質を含むので熱的に冷却する必要がある。このため、このリサイクル燃料集合体は、原子力発電所内の冷却ピットで所定時間（３〜６ヶ月間）冷却される。その後、放射性物質格納容器であるキャスクに収納され、車両又は船舶で再処理施設に輸送貯蔵される。また、リサイクル燃料集合体は上述のように、高放射性物質であるためこれを収納するキャスクは、この放射性物質がキャスク外部に漏れないようするための密閉構造が必要とされる。
【０００３】
図１１は、従来のキャスクの蓋部の構造を示す図である。同図に示すように、キャスク１００は、胴本体１１０と、蓋部１２０とで構成されている。胴本体１１０は、リサイクル燃料集合体などの放射性物質を収納するキャビティ１１１を有する有底円筒状であり、かつ炭素鋼製あるいはステンレス鋼製の鋳造品であり、γ線遮蔽機能を発揮するのに十分な厚みを有している。また、キャビティ１１１上方の開口部１１２は、胴本体１１０の軸方向の断面形状が階段状の形状となっており、段差部１１３が設けられている。なお１´４は、中性子を吸収するための中性子遮蔽体である。蓋部１２０は、一次蓋１３０および二次蓋１４０とから構成されている。一次蓋１３０および二次蓋１４０は、鋼製の円板状部材であり、それぞれその外周にフランジ部１３１´４１が設けられている。また、二次蓋１４０には、その内部に中性子を吸収するための中性子遮蔽体１４２が設けられている。
【０００４】
上記キャスク１００にリサイクル燃料集合体などの放射性物質を収納する際には、放射性物質をキャビティ１１１内に収納し、胴本体１１０の開口部１１２内に一次蓋１３０を取り付け、すなわち胴本体１１０の段差部１１３と一次蓋１３０のフランジ部１３１との間にガスケット１６１を介在させて、ボルト１５１でこの一次蓋１３０を胴本体１１０に固定する。そして、胴本体１１０の開口部１１２を覆うように、二次蓋１４０をこの胴本体１１０に取り付ける、すなわち胴本体１１０の上面１１５と二次蓋１４０のフランジ部１４１との間にガスケット１６２を介在させて、ボルト１５２でこの二次蓋１４０を胴本体１１０に固定することで、キャスク１００の密閉構造を構成する。つまり、従来では、胴本体１１０と一次蓋１３０および二次蓋１４０との間に、密閉手段であるガスケット１６１´６２を介在させることで、放射性物質格納容器であるキャスク１００の密閉の信頼性を確保している。
【０００５】
また、従来では放射性物質格納容器の密閉構造の信頼性を向上させるために、上記密閉手段に加えてシール部材が溶接により取り付けられた密閉構造が提案されている（例えば、特許文献１）。この密閉構造は、胴本体１１０（特許文献１では、キャスク１０）と一次蓋１３０（特許文献１では、内蓋３６）および二次蓋１４０（特許文献１では、外蓋３８）との間を密閉手段（特許文献１では、Ｏリング４２、５２）により密閉し、さらに一次蓋１３０と胴本体１１０を固定するボルト１６１（特許文献１では、ボルト４０）の上方、すなわち胴本体１１０と一次蓋１３０とで形成されている空間部をシール部材（特許文献１では、シールリング４４）で覆い、シール部材とこの胴本体１１０の上面およびシール部材と一次蓋１３０の上面を溶接（密封溶接部４６、４８）する構造である。
【０００６】
【特許文献１】
特開昭６１−７６８９１（図３）
【０００７】
【発明が解決しようとする課題】
ところで、キャスク１００が落下等した際には、胴本体１１０のキャビティ１１１内に収納された放射性物質は一次蓋１３０に衝突する。この衝突により一次蓋１３０は、胴本体１１０の開口部１１２内でこの胴本体１１０の軸方向あるいは径方向に撓んだり、ずれたりする恐れがある。このとき、一次蓋１３０が胴本体１１０の径方向に移動する場合は、上記特許文献１にかかる放射性物質格納容器の密閉構造では、シール部材の一方の端部が一次蓋１３０の上面に溶接されているためシール部材も同様に胴本体１１０の径方向に移動しようとする。しかし、このシール部材の他方の端部は、胴本体１１０の上面に溶接されているので、シール部材は移動することができない。従って、シール部材と胴本体１１０あるいはシール部材と一次蓋１３０とのいずれかの溶接部には、溶接部をせん断する方向に力がかかり、溶接部がせん断される恐れがある。つまり、放射性物質格納容器であるキャスク１００が落下または衝突した際にシール部材と胴本体１１０またはシール部材と内蓋である一次蓋１３０との溶接部がせん断されると、放射性物質格納容器の密閉の信頼性が低下する恐れがある。
【０００８】
また、胴本体１１０のキャビティ１１１にリサイクル燃料集合体などの放射性物質を収納した後に、一次蓋１３０および二次蓋１４０をこの胴本体１１０に固定するキャスク１００の密閉作業は、高放射線下での作業となる。従って、胴本体１１０の開口部１１２にシール部材を挿入する作業時間やこのシール部材を溶接する作業時間の短縮、すなわち放射性物質格納容器の密閉作業時間の短縮を図り、作業員の安全性を向上することが必要である。
【０００９】
そこで、この発明は、上記に鑑みてなされたものであって、放射性物質格納容器の密閉の信頼性を向上させるとともに、放射性物質格納容器が落下又は衝突した際におけるこの放射性物質格納容器の密閉の信頼性を維持することができること、あるいは密閉作業時間の短縮を図り作業員の安全性を向上することの少なくとも一つを達成できる放射性物質格納容器の密閉構造を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記目的を達成するために、この発明では、少なくともキャビティ内にリサイクル燃料集合体その他の放射性物質を収納するととともに、キャビティの周囲に中性子遮蔽体を設けた胴本体と、胴本体に取り付けられた蓋部と、胴本体と蓋部を密閉する密閉手段とを備える放射性物質格納容器の密閉構造において、蓋部は、胴本体のキャビティ上方の開口部内に取り付けられる内蓋と、内蓋の外側に取り付けられる外蓋に備え、胴本体と内蓋との間に少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材が溶接により取り付けられていることを特徴とする。
【００１１】
この発明によれば、胴本体と内蓋との間に少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材が溶接により取り付けられているので、すなわち密閉手段とシール部材とにより胴本体の開口部を密閉しているので、放射性物質格納容器の密閉の信頼性を向上させることができる。また、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、このシール部材が撓むことで、シール部材と胴本体またはシール部材と内蓋との溶接部の変位量を低減でき、この溶接部がせん断される恐れを少なくでき、上記放射性物質格納容器の密閉の信頼性を維持することができる。ここで、密閉手段としては、胴本体と蓋部自体により密閉するもの（例えば、胴本体と蓋部との当接面を階段状に形成することで構成されるラビリンス構造）や胴本体と蓋部との間に介在するもの（例えば、ガスケットやＯリング）などがあげられる（以下同様）。
【００１２】
また、この発明では、請求項１に記載の放射性物質格納容器の密閉構造において、内蓋は、その外周面に開口部に設けられた段差部に当接するフランジ部を有し、シール部材は、内蓋の外周面とフランジ部の上面と胴本体の開口部の内周面とにより形成されるリング状の空間部に挿入されており、且つ胴本体および内蓋に溶接により取り付けられていることを特徴とする。
【００１３】
この発明よれば、内蓋は、その外周面に開口部に設けられた段差部に当接するフランジ部を有し、シール部材は、内蓋の外周面とフランジ部の上面と胴本体の開口部の内周面とにより形成されるリング状の空間部に挿入されており、且つ胴本体および内蓋に溶接により取り付けられているので、すなわち密閉手段とシール部材とにより胴本体の開口部を密閉しているので、放射性物質格納容器の密閉の信頼性を向上させることができる。また、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、リング状の空間部に挿入されたシール部材が撓むことでシール部材と胴本体またはシール部材と内蓋との溶接部の変位量を低減でき、この溶接部がせん断される恐れを少なくでき、上記放射性物質格納容器の密閉の信頼性を維持することができる。
【００１４】
また、この発明では、請求項２に記載の放射性物質格納容器の密閉構造において、シール部材は、当該シール部材の少なくとも両端部のいずれか一方に胴本体の軸方向に延在する腕部を有し、腕部の先端部を胴本体および／または内蓋に溶接することを特徴とする。
【００１５】
この発明によれば、シール部材は、当該シール部材の少なくとも両端部のいずれか一方に胴本体の軸方向に延在する腕部を有し、腕部の先端部を胴本体および／または内蓋に溶接するので、上記請求項２にかかる発明の作用効果に加えて、シール部材を溶接する際に、このシール部材の腕部の先端部と胴本体および／または内蓋との溶接部が内蓋が取り付けられた胴本体の開口部から視認することができ、シール部材の溶接作業を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮を図ることができる。また、放射性物質格納容器を開封するためにシール部材を取り外す際に、シール部材と胴本体および／または内蓋との溶接部は内蓋が取り付けられた胴本体の開口部から視認することができるので、この溶接部を容易にせん断することができ、シール部材の開封作業を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮を図れ、作業員の安全性を向上することができる。
【００１６】
また、この発明では、少なくともキャビティ内にリサイクル燃料集合体その他の放射性物質を収納するととともに、当該キャビティの周囲に中性子遮蔽体を設けた胴本体と、胴本体に取り付けられた蓋部と、胴本体と蓋部を密閉する密閉手段とを備える放射性物質格納容器の密閉構造において、蓋部は、胴本体のキャビティ上方の開口部内に取り付けられる内蓋と、内蓋の外側に取り付けられる外蓋に備え、外蓋と内蓋との間に少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材が溶接により取り付けられていることを特徴とする。
【００１７】
この発明によれば、外蓋と内蓋との間に少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材が溶接により取り付けられているので、すなわち密閉手段とシール部材とにより胴本体の開口部を密閉しているので、放射性物質格納容器の密閉の信頼性を向上させることができる。また、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、このシール部材が撓むことでシール部材と胴本体との溶接部の変位量を低減でき、この溶接部がせん断される恐れを少なくでき、上記放射性物質格納容器の密閉の信頼性を維持することができる。さらに、シール部材と胴本体との溶接部の溶接線は１本であり、このシール部材の溶接作業時間を短縮でき、放射性物質格納容器の密閉作業時間の短縮を図れ、作業員の安全性を向上することができる。
【００１８】
また、この発明では、請求項４に記載の放射性物質格納容器の密閉構造において、シール部材は、内蓋が取り付けられた胴本体の開口部に挿入されており、且つ前記胴本体に溶接により取り付けられていることを特徴とする。
【００１９】
この発明によれば、シール部材は、内蓋が取り付けられた胴本体の開口部に挿入されており、且つ前記胴本体に溶接により取り付けられているので、すなわち密閉手段とシール部材とにより胴本体の開口部を密閉しているので、放射性物質格納容器の密閉の信頼性を向上させることができる。また、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、このシール部材が撓むことでシール部材と胴本体との溶接部の変位量を低減でき、この溶接部がせん断される恐れを少なくでき、上記放射性物質格納容器の密閉の信頼性を維持することができる。さらに、シール部材と胴本体の開口部との溶接部の溶接線は１本となり、このシール部材の溶接作業時間を短縮でき、放射性物質格納容器の密閉作業時間の短縮を図れ、作業員の安全性を向上することができる。
【００２０】
また、この発明では、請求項５に記載の放射性物質格納容器の密閉構造において、シール部材は、シール部材の端部に胴本体の軸方向に延在する腕部を有し、腕部の先端部を胴本体に溶接することを特徴とする。
【００２１】
この発明によれば、シール部材は、シール部材の端部に胴本体の軸方向に延在する腕部を有し、腕部の先端部を胴本体に溶接するので、上記請求項４にかかる発明の作用効果に加えて、シール部材を溶接する際に、このシール部材の腕部の先端部と胴本体の溶接部を内蓋が取り付けられた胴本体の開口部から視認することができ、シール部材の溶接作業を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮を図ることができる。また、放射性物質格納容器を開封するためにシール部材を取り外す際に、シール部材と胴本体との溶接部を内蓋が取り付けられた胴本体の開口部から視認することができるので、この溶接部を容易にせん断することができ、シール部材の開封作業を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮をさらに図れ、作業員の安全性をさらに向上することができる。
【００２２】
また、この発明では、請求項３または６に記載の放射性物質格納容器の密閉構造において、腕部は、胴本体の開口部の内周面および／または内蓋の外周面に胴本体の径方向に付勢された状態で接触していることを特徴とする。
【００２３】
この発明によれば、腕部は、胴本体の開口部の内周面および／または内蓋の外周面に胴本体の径方向に付勢された状態で接触しているので、シール部材をリング状の空間部あるいは胴本体の開口部に挿入した際に、この挿入されたシール部材の挿入位置を維持することができる。これにより、シール部材を溶接する際に、このシール部材を挿入位置で保持する保持手段を必要としないので、シール部材の溶接を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮をさらに図れ、作業員の安全性をさらに向上することができる。
【００２４】
また、この発明では、請求項１〜７のいずれか一つに記載の放射性物質格納容器の密閉構造において、シール部材は、胴本体の軸方向に突出する突出部を有することを特徴とする。
【００２５】
この発明によれば、シール部材は、胴本体の軸方向に突出する突出部を有するので、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、シール部材、特にシール部材の突出部が撓み、シール部材と胴本体またはシール部材と内蓋との溶接部の変位量をさらに低減でき、この溶接部がせん断される恐れをさらに小さくでき、上記放射性物質格納容器の密閉の信頼性をさらに維持することができる。
【００２６】
また、この発明では、請求項１〜８のいずれか一つに記載の放射性物質格納容器の密閉構造において、シール部材が溶接される胴本体および／または内蓋にリング状の溶接突起部を設けたことを特徴とする。
【００２７】
この発明によれば、シール部材が溶接される胴本体および／または内蓋にリング状の溶接突起部を設けるので、胴本体または一次蓋自体に比べて、胴本体および／または内蓋にシール部材を溶接する溶接個所の熱容量が小さでき、すなわちシール部材の熱容量に近づけることができ、シール部材の溶接を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮をさらに図れ、作業員の安全性をさらに向上することができる。ここで、溶接突起部は、胴本体や内蓋を切削することで設けても良いし、リング状の部材を胴本体や内蓋に取り付けても良い。
【００２８】
また、この発明では、キャビティ内にリサイクル燃料集合体その他の放射性物質を収納するととともに、キャビティの周囲に中性子遮蔽体を設けた胴本体と、胴本体に取り付けられた蓋部とを備えた放射性物質格納容器の密閉構造において、少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材で蓋部を覆い、シール部材の端部を胴本体に設けた中性子遮蔽体を覆う外筒に溶接より取り付けることを特徴とする。
【００２９】
この発明によれば、少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材で蓋部を覆い、シール部材の端部を胴本体に設けた中性子遮蔽体を覆う外筒に溶接より取り付けるので、すなわち密閉手段とシール部材とにより胴本体の開口部を密閉しているので、放射性物質格納容器の密閉の信頼性を向上させることができる。また、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、このシール部材が撓むことで、シール部材と胴本体の外筒との溶接部の変位量を低減でき、この溶接部がせん断される恐れを少なくでき、上記放射性物質格納容器の密閉の信頼性を維持することができる。さらに、シール部材は、胴本体と蓋部を密閉手段により密閉した後に胴本体の外筒に溶接により取り付けはすでに高放射線下の作業ではないので、作業員の安全性を向上することができる。
【００３０】
【発明の実施の形態】
以下、この発明につき図面を参照しつつ詳細に説明する。なお、この実施の形態によりこの発明が限定されるものではない。また、下記実施の形態における構成要素には、当業者が容易に想定できるもの或いは実質的に同一のものが含まれる。
【００３１】
〔第一実施形態〕
図１は、第一実施形態の放射性物質格納容器の軸方向断面図である。ここで、放射性物質格納容器には、キャスクやキャニスタ等が含まれる。同図に示すように、放射性物質格納容器１は、胴本体２と、蓋部３とにより構成されている。胴本体２は、開口部２ａを有する中空円筒形状であり、その底部に円板状の底板４が溶接によって取り付けられている。この胴本体２の中空部と底板４とで形成される空間であるキャビティ２ｂ内にリサイクル燃料集合体などの放射性物質Ｒを装荷する図示しないバスケット等が収納されている。ここで、胴本体２および底板４は、炭素鋼製の鍛造品でありγ線遮蔽機能を発揮するのに十分な厚みを有している。なお、胴本体２の外形に合わせた内部形状を有するコンテナ内に金属ビレットを装入し、胴本体２の内径に合わせた外径を有する穿孔ポンチで、この金属ビレットを熱間拡張成形することによって胴本体２と底板４を一体に成形して良いし、鋳造により製造しても良い。
【００３２】
また、胴本体２の外周部には、外筒５が図示しないアルミニウム板や銅板等の熱の良導材料で形成される複数の伝熱フィンを介して取り付けられている。この伝熱フィンには、キャビティ２ｂ内に収納された放射性物質Ｒから発生する崩壊熱が胴本体２を介して伝わる。この伝熱フィンに伝わった放射性物質Ｒからの崩壊熱は、外筒５に伝導された後、外筒５の表面から大気中に放出される。この外筒５と胴本体２との間には、水素を多く含有する高分子材料であるレジン、ポリウレタン、シリコンなどの中性子吸収体６が充填されている。なお、底板４にも同様に中性子吸収体６が封入されている。
【００３３】
蓋部３は、同図に示すように、内蓋である一次蓋７と外蓋である二次蓋８とにより構成されている。この一次蓋７および二次蓋８は、γ線を遮蔽する炭素鋼製またはステンレス鋼製の円板形状である。一次蓋７は、その外周部に胴本体２の開口部２ａとキャビティ２ｂとの間に設けられた段差部２ｃに当接するフランジ部７ａが設けられている。一方、二次蓋８は、その外周部に胴本体２の上面２ｄに当接するフランジ部８ａが設けられ、中性子吸収体６が封入されている。一次蓋７および二次蓋８は、それぞれ複数個のボルト９ａ、９ｂで胴本体２に固定されている。なお、８ｂは、放射性物質格納容器１が落下または衝突した際に、一次蓋７にかかる荷重を二次蓋８に分担させるための荷重伝達機構である荷重用突起である。
【００３４】
放射性物質格納容器１の密閉構造は、密閉手段であるガスケット１０ａ、１０ｂとシール部材１２により構成されている。ガスケット１０ａ、１０ｂは、リング状の金属製であり、それぞれ胴本体２と一次蓋７との間および胴本体２と二次蓋８との間に介在されている。
【００３５】
図２は、第一実施形態のシール部材の構成例を示す図であり、同図（ａ）は図１（ａ）のＡ部分拡大図、同図（ｂ）はシール部材の平面図、同図（ｃ）は空間部に挿入される前のシール部材の軸方向断面図である。シール部材１２は、同図（ｂ）に示すように、リング状であり、炭素鋼製あるいはステンレス鋼製である。このリング状のシール部材１２は、同図（ａ）に示すように、一次蓋７のフランジ部７ａの上方、すなわちこの一次蓋７の外周面とフランジ部７ａの上面（ボルト９ａの上面も含まれる）と胴本体２の開口部２ａの内周面とに形成されるリング状の空間部１１に挿入されている。シール部材１２は、胴本体２の軸方向の上方に突出部１２ａと胴本体２の軸方向の下方に突出部１２ｂ、１２ｃが設けられている。また、シール部材１２の両端部は、胴本体２の軸方向（同図（ｂ）では、上方）に延在する腕部１２ｄ、１２ｅが設けられている。すなわち、シール部材１２は、その軸方向断面形状が上記空間部１１に挿入された状態では、Ｍ字を逆にした形状となっている。
【００３６】
シール部材１２の空間部１１に挿入する前の形状は、同図（ｃ）に示すように、その腕部１２ｄ、１２ｅの先端部１２ｆ、１２ｇの幅ｄ１が、シール部材１２を挿入する空間部１１の幅ｄ２よりも広い形状、すなわち、その軸方向断面形状がＷ字の形状である。従って、胴本体２および一次蓋７の製作公差により、空間部１１の幅ｄ１が不均一な場合においても、シール部材１２の突出部１２ａ、１２ｂ、１２ｃが撓むとで、シール部材１２を空間部１１に容易に挿入することができる。また、空間部１１に挿入されたシール部材１２の腕部１２ｄ、１２ｅは、それぞれ胴本体２の開口部２ａの内周面と一次蓋７の外周面に付勢された状態で接触する。これにより、シール部材１２は、空間部１１に挿入された挿入位置を維持することができ、シール部材１２を溶接する際にこのシール部材１２を挿入位置で保持する保持手段を必要せず、シール部材１２の溶接作業を容易に行うことができる。また、空間部１１に挿入されたシール部材１２の先端部１２ｆ、１２ｇは、胴本体２の開口部２ａの内周面と一次蓋７の外周面に接触した状態を維持できるので、シール部材１２の溶接作業を容易に行うことができる。また、腕部１２ｄ、１２ｅの先端部１２ｆ、１２ｇは、一次蓋７が取り付けられた胴本体２の開口部２ａから視認することができ、シール部材１２の溶接作業を容易に行うことができる。さらに、シール部材１２は、リング状であり、且つ空間部１１に容易に挿入することができるので、製作に高い精度が要求されず、このシール部材１２の製造コストを低減することができる。
【００３７】
胴本体２の開口部２ａの内周面と一次蓋７の外周面には、腕部１２ｄ、１２ｅの先端部１２ｆ、１２ｇが接触する位置に、それぞれ溶接用突起部２ｅ、７ｂが切削加工などにより設けられている。シール部材１２は、このシール部材１２の腕部１２ｄの先端部１２ｆと胴本体２の溶接用突起部２ｅと、腕部１２ｅの先端部１２ｇと溶接用突起部７ｂとを溶接することで、シール部材１２は胴本体２と一次蓋７との間に取り付けられている。このシール部材１２の溶接は、例えば、ＴＩＧ溶接、レーザ溶接などにより行われる。また、胴本体２の溶接用突起部２ｅおよび一次蓋７の溶接用突起部７ｂは、胴本体２または一次蓋７自体に比べて熱容量が小さいので、すなわちシール部材１２の先端部１２ｆ、１２ｇの熱容量に近づくので、シール部材１２の溶接を容易に行うことができる。
【００３８】
一次蓋７が撓んだり、ずれることで、この一次蓋７は胴本体２の径方向に移動すると、図２（ａ）に示すシール部材１２が挿入されている空間部１１の幅ｄ１が変位する（長くなったり、短くなったりする）。シール部材１２の腕部１２ｄ、１２ｅの幅は、空間部１１の幅ｄ１の変位に追従して変位するが、このシール部材１２の突起部１２ａ、１２ｂ、１２ｃが撓むことで、上記変位量を吸収される。従って、シール部材１２と胴本体２および一次蓋７との溶接部Ｓの変位量を低減することができる。これにより、放射性物質格納容器１が落下又は衝突した際にシール部材１２が胴本体２の径方向に移動しても、この溶接部がせん断される恐れを少なくできる。
【００３９】
なお、シール部材１２の腕部１２ｄ、１２ｅの長さを図３（ａ）に示すように、同一の長さとしても良い。これにより、放射性物質格納容器１が落下又は衝突した際に、一次蓋７の胴本体２の径方向の移動による空間部１１の幅の変位に追従して変位するが、このシール部材１２の突起部１２ａ、１２ｂ、１２ｃが撓むことで、上記変位量を吸収し、且つシール部材１２と胴本体２および一次蓋７との溶接部Ｓの変位量が均一にすることができるので、この溶接部Ｓのいずれかの変位量が大きくなることを防止でき、この溶接部がせん断される恐れをさらに少なくできる。これにより、放射性物質格納容器１が落下又は衝突した際にシール部材１２が胴本体２の径方向に移動しても、この放射性物質格納容器１の密閉の信頼性をさらに維持することができる。また、一次蓋７が胴本体２の径方向に移動する量がわずかである場合は、図３（ｂ）に示すように、シール部材１２のその軸方向断面形状をシール部材１２の成形が容易な形状、すなわち突出部１２ａ、１２ｂ、１２ｃがないＵ字形状としても良い。この場合は、シール部材１２の空間部１１に挿入する前の形状が、その腕部１２ｄ、１２ｅの先端部１２ｆ、１２ｇの幅が、シール部材１２を挿入する空間部１１の幅よりも広い形状であることが好ましい。
【００４０】
放射性物質格納容器１を上記のような密封構造とすることにより、放射性物質格納容器１の密閉の信頼性を向上させることができるとともに、放射性物質格納容器１が落下又は衝突した際にシール部材１２が胴本体２の径方向に移動しても、この放射性物質格納容器１の密閉の信頼性を維持することができる。
【００４１】
図４は、シール部材の他の構成例を示す図である。同図（ａ）に示すように、シール部材１２´は、シール部材１２と同様にリング状の空間部１１に挿入されている。シール部材１２´は、胴本体２の近傍にこの胴本体２の軸方向の下方に突出部１２ｂが設けられている。また、シール部材１２´の胴本体２側の端部は、胴本体２の軸方向（同図（ａ）では、上方）に延在する腕部１２ｄが設けられている。胴本体２の開口部２ａの内周面と一次蓋７の外周面には、シール部材１２´の腕部１２ｄの先端部１２ｆと一次蓋７側の端部１２ｈのそれぞれが接触する位置に、溶接用突起部２ｅ、７ｂ´が切削加工などにより設けられている。シール部材１２´は、このシール部材１２´の腕部１２ｄの先端部１２ｆを胴本体２の溶接用突起部２ｅに、端部１２ｈを溶接用突起部７ｂに溶接することで、胴本体２と一次蓋７との間に取り付けられている。
【００４２】
このシール部材１２´の端部１２ｈが開口部１１に挿入されないので、シール部材１２´をこの開口部１１に挿入する際に、腕部１２ｄの先端部１２ｆと胴本体２の溶接用突起部２ｅとの位置を合わせるだけで、シール部材１２´の空間部１１に対する挿入位置を設定することができる。また、シール部材１２´の溶接は、腕部１２ｄの先端部１２ｆと胴本体２の溶接用突起部２ｅから行うのが良い。これにより、シール部材１２´を空間部１１の挿入位置に保持することができる。なお、溶接用突起部７ｂ´の高さは、その上面に溶接されるシール部材１２´の端部１２ｈの上面が一次蓋７の上面を越えない高さに設定されている。これは、一次蓋７が胴本体２の軸方向に移動して二次蓋８と接触した際に、シール部材１２´の端部１２ｈと溶接用突起部７ｂ´との溶接部Ｓが二次蓋８の下面に接触して損傷しないようにするためである。
【００４３】
この放射性物質格納容器１の密封構造は、シール部材１２の代わりにシール部材１２´を空間部１１に挿入され、このシール部材１２´を胴本体２と一次蓋７とに溶接した点を除けば、図１に示す放射性物質格納容器１と同様である。放射性物質格納容器１が落下又は衝突した際に、一次蓋７が胴本体２の径方向に移動し、シール部材１２´の端部１２ｈと腕部１２ｄとの幅が、空間部１１の幅の変位に追従して変位しても、このシール部材１２´の突起部１２ｂが撓むことで、上記変位量を吸収する。従って、シール部材１２´と胴本体２および一次蓋との溶接部Ｓのいずれについても、この溶接部Ｓの変位量を低減できる。これにより、放射性物質格納容器１が落下又は衝突した際にシール部材１２´が胴本体２の径方向に移動しても、この溶接部Ｓがせん断される恐れがない。従って、放射性物質格納容器１を上記のような密封構造とすることにより、放射性物質格納容器１の密閉の信頼性を向上させることができるとともに、放射性物質格納容器１が落下又は衝突した際にシール部材１２´が胴本体２の径方向に移動しても、この放射性物質格納容器１の密閉の信頼性を維持することができる。
【００４４】
ここで、放射性物質格納容器１の密閉状態は、一次蓋７と二次蓋８との間の圧力を監視することで行うが、この圧力を正確に検知するためには一定量の容積が必要である。上記シール部材１２´では、その下部、すなわちシール部材１２´の下面と一次蓋７のフランジ７ａの上面との間の空間の容積を大きくできるので、この空間内で圧力を検知すれば、放射性物質格納容器１の密閉状態の監視を適格に行うことができる。なお、同図（ｂ）に示すように、一次蓋７の溶接用突起部７ｂ´を設けずに、シール部材１２´の一次蓋７側の端部をこの一次蓋７自体に直接溶接しても良い。これにより、シール部材１２´と一次蓋７との溶接部を強固なものとすることができる。
【００４５】
上記実施形態では、蓋部３が内蓋である一次蓋７と外蓋である二次蓋８とで構成される放射性物質格納容器１の密閉構造について説明したが、本発明はこれに限定されるものではなく、内蓋を二重構造とした放射性物質格納容器にも用いることができる。図５は、内蓋を二重構造とした放射性物質格納容器の密閉構造の構成例を示す図である。この放射性物質格納容器１´が図１に示す放射性物質格納容器１と異なる点は、内蓋を一次蓋７と支持蓋１３との二重構造にした点である。この放射性物質格納容器１´の蓋部３は、一次蓋７と二次蓋８と支持蓋１３により構成されている。支持蓋１３は、一次蓋７および二次蓋８と同様にγ線を遮蔽する炭素鋼製またはステンレス鋼製の円板形状であり、その外周部に胴本体２の開口部２ａの段差部２ｃの下側、すなわちキャビティ２ｂ側に設けられた段差部２ｆに当接するフランジ部１３ａが設けられている。支持蓋１３は、複数個のボルト９ｃで胴本体２に、一次蓋７と間隙２ｇを設けた状態で固定されている。
【００４６】
この放射性物質格納容器１´の密封構造は、図１に示す放射性物質格納容器１と同様に、胴本体２と一次蓋７との間および胴本体２と二次蓋の間に介在されている密閉手段であるガスケット１０ａ、１０ｂと、空間部１１に挿入され胴本体２と一次蓋７とに溶接されたシール部材１２とにより構成されている。図５に示す放射性物質格納容器１´が落下や衝突し、胴本体２のキャビティ２ｂ内に収納された図示しない放射性物質が支持蓋１３に衝突することで、支持蓋１３が胴本体２の開口部２ａ内でこの胴本体２の軸方向あるいは径方向に撓んだり、ずれたりしても、支持蓋１３からの荷重は間隙２ｇがあるため一次蓋７に分担されない。つまり、支持蓋１３が胴本体２の径方向に移動しても、一次蓋７は支持蓋１３の移動に追従して移動しなので、一次蓋７が自重で撓んだり、ずれたりしない限り、この一次蓋７の空間部１１に挿入され、溶接されているシール部材１２は、胴本体２の径方向の変位を生じない。従って、放射性物質格納容器１´を上記のような密封構造とすることにより、放射性物質格納容器１´の密閉の信頼性を向上させることができるとともに、放射性物質格納容器１´が落下又は衝突した際に支持蓋１３が移動しても、シール部材１２が胴本体２の径方向に移動しないので、この放射性物質格納容器１´の密閉の信頼性をさらに維持することができる。
【００４７】
なお、図６に示すように、シール部材１２を胴本体２と内蓋である支持蓋１３との間、すなわち支持蓋１３の外周面とフランジ部１３ａの上面（ボルト９ｃの上面も含まれる）と胴本体２の開口部２ａの内周面とに形成されるリング状の空間部１４に挿入し、溶接により取り付けても良い。この放射性物質格納容器１´の密封構造は、図１に示す放射性物質格納容器１と同様に、胴本体２と一次蓋７との間および胴本体２と二次蓋の間に介在されている密閉手段であるガスケット１０ａ、１０ｂと空間部１４に挿入され胴本体２と支持蓋１３とに溶接されたシール部材１２とにより構成されている。放射性物質格納容器１´が落下又は衝突した際にこの支持蓋１３が胴本体２の径方向に移動し、シール部材１２の腕部１２ｄ、１２ｅの幅が空間部１４の幅の変位に追従して変位しても、このシール部材１２の突起部１２ａ、１２ｂ、１２ｃが撓むことで、上記変位量を吸収する。従って、シール部材１２と胴本体２および支持蓋１３との溶接部Ｓのいずれについても、この溶接部Ｓの変位量を低減することができる。これにより、放射性物質格納容器１´が落下又は衝突した際にシール部材１２が胴本体２の径方向に移動しても、この溶接部Ｓがせん断される恐れを少なくできる。従って、放射性物質格納容器１´を上記のような密封構造とすることにより、放射性物質格納容器１´の密閉の信頼性を向上させることができるとともに、放射性物質格納容器１´が落下又は衝突した際にシール部材１２が胴本体２の径方向に移動しても、この放射性物質格納容器１´の密閉の信頼性を維持することができる。
【００４８】
ここで、上記放射性物質格納容器１´、１´のシール部材１２を図３（ａ）に示すような腕部１２ｄ、１２ｅの長さを同一の長さとしたシール部材１２や図３（ｂ）に示すような突出部１２ａ、１２ｂ、１２ｃがない成形が容易な形状としてもよい。また、シール部材１２の代わりにシール部材１２´を用いても良い。
【００４９】
〔第二実施形態〕
図７は、第二実施形態の放射性物質格納容器の軸方向断面図である。図７に示す第二実施形態の放射性物質格納容器２０は、図１に示す第一実施形態の放射性物質格納容器１とその基本的構成は同一であるので説明は省略する。この放射性物質格納容器２０が、図１に示す放射性物質格納容器１と異なる点は、内蓋である一次蓋７と外蓋である二次蓋８との間に、シール部材１５を設けた点にある。この放射性物質格納容器３０の密閉構造は、密閉手段であるガスケット１０ａ、１０ｂとシール部材１５により構成されている。
【００５０】
図８は、第二実施形態のシール部材の構成例を示す図であり、同図（ａ）は図１（ａ）のＢ部分拡大図、同図（ｂ）はシール部材の平面図、同図（ｃ）は空間部に挿入される前のシール部材の軸方向断面図である。シール部材１５は、同図（ｂ）に示すように、円板状であり、炭素鋼製あるいはステンレス鋼製である。この円板状のシール部材１５は、同図（ａ）に示すように、一次蓋７と二次蓋８との間で、かつ一次蓋７の上面を覆うように胴本体２の開口部２ａに挿入されている。シール部材１５は、その端部近傍に胴本体２の軸方向の上方に突出部１５ａが設けられている。また、シール部材１５の端部は、胴本体２の軸方向（同図（ｂ）では、上方）に延在する腕部１５ｂが設けられている。
【００５１】
シール部材１５の開口部２ａに挿入する前の形状は、同図（ｃ）に示すように、その腕部１５ｂの先端部１５ｃの幅ｄ３が、シール部材１５を挿入する開口部２ａの幅ｄ４よりも広い形状である。従って、シール部材１５の製作公差により、先端部１５ｃの幅ｄ４が不均一な場合においても、シール部材１５の突出部１５ａが撓むことで、シール部材１５は開口部２ａに容易に挿入することができる。また、開口部２ａに挿入されたシール部材１５の腕部１５ｂは、胴本体２の開口部２ａの内周面に付勢された状態で接触する。これにより、シール部材１５は、開口部２ａに挿入された挿入位置を維持することができ、シール部材１５を溶接する際にこのシール部材１５を挿入位置で保持する保持手段を必要せず、シール部材１５の溶接作業を容易に行うことができる。また、開口部２ａに挿入されたシール部材１５の先端部１５ｃは、胴本体２の開口部２ａの内周面に接触した状態を維持できるので、シール部材１５の溶接作業を容易に行うことができる。また、腕部１５ｂの先端部１５ｃは、胴本体２の開口部２ａから視認することができ、シール部材１５の溶接作業を容易に行うことができる。
【００５２】
胴本体２の開口部２ａの内周面には、腕部１５ｂの先端部１５ｃが接触する位置に、溶接用突起部２ｅが切削加工などにより設けられている。シール部材１５は、このシール部材１５の腕部１５ｂの先端部１５ｃと胴本体２の溶接用突起部２ｅとを溶接することで、一次蓋７と二次蓋８との間に取り付けられている。このシール部材１５の溶接は、例えば、ＴＩＧ溶接、レーザ溶接などにより行われる。また、胴本体２の溶接用突起部２ｅは、胴本体２自体に比べて熱容量が小さいので、すなわちシール部材１５の先端部１５ｃの熱容量に近づくので、シール部材１５の溶接を容易に行うことができる。さらに、シール部材１５と胴本体２との溶接部Ｓは一箇所、つまり溶接部Ｓの溶接線は１本であるので、このシール部材１５の溶接作業時間を短縮できる。また、溶接部Ｓが一箇所なので、シール部材１５の溶接部Ｓをせん断し、このシール部材１５を胴本体２の開口部２ａから取り外す作業を短時間で行うことができる。
【００５３】
放射性物質格納容器２０が落下又は衝突した際に、一次蓋７が撓んだり、ずれることで、この一次蓋７は胴本体２の軸方向あるいは径方向に移動する場合がある。一次蓋７が胴本体２の径方向だけに移動した場合は、シール部材１５は一次蓋７に固定されていないため、このシール部材１５が一次蓋７に接触していても胴本体２の径方向に対する変位量は少ない。一次蓋７が胴本体２の軸方向と径方向に移動した場合は、まず、一次蓋７がシール部材１５を介して二次蓋８の荷重用突起部８に衝突する。この際、シール部材１５は、一次蓋７と二次蓋８との間に密着するので、シール部材１５の胴本体の径方向に対する変位量は、一次蓋７が移動した際の変位量に追従する。上記いずれの場合においても、シール部材１５の突起部１５ａが撓むことで、上記変位量を吸収する。従って、シール部材１５と胴本体２との溶接部Ｓの変位量を低減することができる。これにより、放射性物質格納容器２０が落下又は衝突した際にシール部材１５が胴本体２の径方向に移動しても、この溶接部Ｓがせん断される恐れを少なくできる。
【００５４】
なお、上記実施形態例では、放射性物質格納容器２０が落下または衝突した際に、一次蓋７にかかる荷重を二次蓋８に分担させるため荷重伝達機構として、二次蓋８に荷重用突起８ｂを設けたが、図９（ａ）に示すように、シール部材１５の上面に荷重用突起１５ｄを設けても良い。また、図９（ｂ）に示すように、荷重用突起１５ｄは、シール部材１５の下側に設けても良い。
【００５５】
放射性物質格納容器２０を上記のような密封構造とすることにより、放射性物質格納容器２０の密閉の信頼性を向上させることができるとともに、放射性物質格納容器２０が落下又は衝突した際にシール部材１２が胴本体２の径方向に移動しても、この放射性物質格納容器２０の密閉の信頼性を維持することができる。
【００５６】
〔第三実施形態〕
図１０は、第三実施形態の放射性物質格納容器の要部断面図である。図１０に示す第三実施形態の放射性物質格納容器３０は、図１に示す第一実施形態の放射性物質格納容器１とその基本的構成は同一であるので説明は省略する。この放射性物質格納容器３０が、図１に示す放射性物質格納容器１と異なる点は、蓋部３覆うシール部材１６を設けた点にある。この放射性物質格納容器３０の密閉構造は、密閉手段であるガスケット１０ａ、１０ｂとシール部材１６とにより構成されている。
【００５７】
シール部材１６は、円板部１６ａと外周部１６ｂとから構成され、その軸方向断面形状が凹状であり、炭素鋼製あるいはステンレス鋼製である。このシール部材１６は、放射性物質格納容器３０に一次蓋７と二次蓋８が取り付けられた状態で、蓋部３、すなわち二次蓋８の外周面を覆うように被せられている。シール部材１６の外周部１６ｂの下端部には、胴本体２の径方向に延在する腕部１６ｃが設けられている。シール部材１６は、このシール部材１６の腕部１６ｃの先端部１６ｄと外筒５とを溶接することで、蓋部３を覆うように取り付けられている。なお、シール部材１６が取り付けられた放射性物質格納容器３０は、輸送時に図示しない緩衝体が蓋部３を覆うように、すなわちシール部材１６を覆うように取り付けられている。ここで、外筒５は、胴本体２自体に比べて熱容量が小さいので、すなわちシール部材１６の先端部１６ｃの熱容量に近づくので、シール部材１６の溶接を容易に行うことができる。さらに、シール部材１６と外筒５との溶接部Ｓは一箇所、つまり溶接部Ｓの溶接線は１本であるので、このシール部材１６の溶接作業時間を短縮できる。また、溶接部Ｓが一箇所なので、この溶接部Ｓをせん断することで、このシール部材１６を胴本体２に設けられた外筒５から取り外す作業を短時間で行うことができる。また、腕部１６ｃの先端部１６ｄは、放射性物質格納容器３０の上方から視認することができ、シール部材１６の溶接作業を容易に行うことができる。
【００５８】
放射性物質格納容器３０が落下又は衝突した際に、一次蓋７が撓んだり、ずれることで、一次蓋７が胴本体２の軸方向と径方向に移動した場合は、まず、一次蓋７がシール部材１５を介して二次蓋８の荷重用突起部８に衝突する。一次蓋７の荷重は、一次蓋７が二次蓋８に衝突することで二次蓋８が分担するため、この二次蓋８も胴本体２の軸方向と径方向に移動する。シール部材１６の外周部１６ｂは、二次蓋８の外周面に密着しているので、シール部材１６の胴本体２の径方向に対する変位量は、二次蓋８が移動した際の変位量に追従する。シール部材１６は、シール部材１６の外周部１６ｂと腕部１６ｃとの接合部１６ｅが撓むことで、上記変位量を吸収する。従って、シール部材１６と外筒５との溶接部Ｓの変位量を低減することができる。これにより、放射性物質格納容器２０が落下又は衝突した際にシール部材１６が胴本体２の径方向に移動しても、この溶接部Ｓがせん断される恐れを少なくできる。
【００５９】
放射性物質格納容器３０を上記のような密封構造とすることにより、放射性物質格納容器３０の密閉の信頼性を向上させることができるとともに、放射性物質格納容器３０が落下又は衝突した際にシール部材１６が胴本体２の径方向に移動しても、この放射性物質格納容器３０の密閉の信頼性を維持することができる。
【００６０】
【発明の効果】
以上説明したように、請求項１および請求項２に記載の発明によれば、胴本体と内蓋との間に少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材が溶接により取り付けられているので、すなわち密閉手段とシール部材とにより胴本体の開口部を密閉しているので、放射性物質格納容器の密閉の信頼性を向上させることができる。また、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、このシール部材が撓むことで、シール部材と胴本体またはシール部材と内蓋との溶接部の変位量を低減でき、この溶接部がせん断される恐れを少なくでき、上記放射性物質格納容器の密閉の信頼性を維持することができる。
【００６１】
また、請求項３に記載の発明によれば、シール部材は、当該シール部材の少なくとも両端部のいずれか一方に胴本体の軸方向に延在する腕部を有し、腕部の先端部を胴本体および／または内蓋に溶接するので、シール部材を溶接する際に、このシール部材の腕部の先端部と胴本体および／または内蓋との溶接部が内蓋が取り付けられた胴本体の開口部から視認することができ、シール部材の溶接作業を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮を図ることができる。また、放射性物質格納容器を開封するためにシール部材を取り外す際に、シール部材と胴本体および／または内蓋との溶接部は内蓋が取り付けられた胴本体の開口部から視認することができるので、この溶接部を容易にせん断することができ、シール部材の開封作業を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮を図れ、作業員の安全性を向上することができる。
【００６２】
また、請求項４および５に記載の発明によれば、外蓋と内蓋との間に少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材が溶接により取り付けられているので、すなわち密閉手段とシール部材とにより胴本体の開口部を密閉しているので、放射性物質格納容器の密閉の信頼性を向上させることができる。また、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、このシール部材が撓むことでシール部材と胴本体との溶接部の変位量を低減でき、この溶接部がせん断される恐れを少なくでき、上記放射性物質格納容器の密閉の信頼性を維持することができる。さらに、シール部材と胴本体との溶接部の溶接線は１本であり、このシール部材の溶接作業時間を短縮でき、放射性物質格納容器の密閉作業時間の短縮を図れ、作業員の安全性を向上することができる。
【００６３】
また、請求項６に記載の発明によれば、シール部材は、シール部材の端部に胴本体の軸方向に延在する腕部を有し、腕部の先端部を胴本体に溶接するので、シール部材を溶接する際に、このシール部材の腕部の先端部と胴本体の溶接部を内蓋が取り付けられた胴本体の開口部から視認することができ、シール部材の溶接作業を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮を図ることができる。また、放射性物質格納容器を開封するためにシール部材を取り外す際に、シール部材と胴本体との溶接部を内蓋が取り付けられた胴本体の開口部から視認することができるので、この溶接部を容易にせん断することができ、シール部材の開封作業を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮をさらに図れ、作業員の安全性をさらに向上することができる。
【００６４】
また、請求項７に記載の発明によれば、腕部は、胴本体の開口部の内周面および／または内蓋の外周面に胴本体の径方向に付勢された状態で接触しているので、シール部材をリング状の空間部あるいは胴本体の開口部に挿入した際に、この挿入されたシール部材の挿入位置を維持することができる。これにより、シール部材を溶接する際に、このシール部材を挿入位置で保持する保持手段を必要としないので、シール部材の溶接を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮をさらに図れ、作業員の安全性をさらに向上することができる。
【００６５】
また、請求項８に記載の発明によれば、シール部材は、胴本体の軸方向に突出する突出部を有するので、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、シール部材、特にシール部材の突出部が撓み、シール部材と胴本体またはシール部材と内蓋との溶接部の変位量をさらに低減でき、この溶接部がせん断される恐れをさらに小さくでき、上記放射性物質格納容器の密閉の信頼性をさらに維持することができる。
【００６６】
また、請求項９に記載の発明によれば、シール部材が溶接される胴本体および／または内蓋にリング状の溶接突起部を設けるので、胴本体または一次蓋自体に比べて、胴本体および／または内蓋にシール部材を溶接する溶接個所の熱容量が小さでき、すなわちシール部材の熱容量に近づけることができ、シール部材の溶接を容易に行うことができ、放射性物質格納容器の密閉作業時間の短縮をさらに図れ、作業員の安全性をさらに向上することができる。
【００６７】
また、請求項１０に記載の発明によれば、少なくとも胴本体の径方向に可とう性を有する密閉手段とは異なるシール部材で蓋部を覆い、シール部材の端部を胴本体に設けた中性子遮蔽体を覆う外筒に溶接より取り付けるので、すなわち密閉手段とシール部材とにより胴本体の開口部を密閉しているので、放射性物質格納容器の密閉の信頼性を向上させることができる。また、放射性物質格納容器が落下又は衝突した際にシール部材が胴本体の径方向に移動しても、このシール部材が撓むことで、シール部材と胴本体の外筒との溶接部の変位量を低減でき、この溶接部がせん断される恐れを少なくでき、上記放射性物質格納容器の密閉の信頼性を維持することができる。さらに、シール部材は、胴本体と蓋部を密閉手段により密閉した後に胴本体の外筒に溶接により取り付けはすでに高放射線下の作業ではないので、作業員の安全性を向上することができる。
【図面の簡単な説明】
【図１】第一実施形態の放射性物質格納容器の軸方向断面図である。
【図２】第一実施形態のシール部材の構成例を示す図であり、同図（ａ）は図１（ａ）のＡ部分拡大図、同図（ｂ）はシール部材の平面図、同図（ｃ）は空間部に挿入される前のシール部材の軸方向断面図である。
【図３】シール部材の他の構成例を示す図である。
【図４】シール部材の他の構成例を示す図である。
【図５】内蓋を二重構造とした放射性物質格納容器の密閉構造の構成例を示す図である。
【図６】内蓋を二重構造とした放射性物質格納容器の密閉構造の構成例を示す図である。
【図７】第二実施形態の放射性物質格納容器の軸方向断面図である。
【図８】第二実施形態のシール部材の構成例を示す図であり、同図（ａ）は図１（ａ）のＢ部分拡大図、同図（ｂ）はシール部材の平面図、同図（ｃ）は空間部に挿入される前のシール部材の軸方向断面図である。
【図９】シール部材の他の構成例を示す図である。
【図１０】第三実施形態の放射性物質格納容器の軸方向断面図である。
【図１１】従来のキャスクの蓋部の構造を示す図である。
【符号の説明】
１、１´　　放射性物質格納容器
２　　　　　胴本体
３　　　　　蓋部
４　　　　　底板
５　　　　　外筒
６　　　　　中性子遮蔽体
７　　　　　内蓋
８　　　　　外蓋
９ａ〜ｃ　　ボルト
１０ａ、ｂ　ガスケット
１１　　　　空間部
１２、１２´　シール部材
１２ａ〜ｃ　突出部
１２ｄ、ｅ　腕部
１３　　　　支持蓋
１４　　　　空間部
１５　　　　シール部材
１６　　　　シール部材
２０　　　　放射性物質格納容器
３０　　　　放射性物質格納容器[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed structure of a radioactive material storage container for storing a burned recycled fuel assembly, and more particularly, to a sealed structure of a radioactive material storage container constituted by sealing means and a sealing member different from the sealing means. About.
[0002]
[Prior art]
A nuclear fuel assembly that has finished burning in the cycle of a nuclear fuel cycle is called a recycled fuel assembly. Since the recycled fuel assembly contains highly radioactive materials such as FP, it must be thermally cooled. For this reason, this recycled fuel assembly is cooled for a predetermined time (for 3 to 6 months) in the cooling pit in the nuclear power plant. Then, it is stored in a cask which is a radioactive substance storage container, and transported and stored in a reprocessing facility by vehicle or ship. Further, as described above, since the recycled fuel assembly is a highly radioactive substance, the cask for accommodating the recycle fuel assembly needs to have a closed structure for preventing the radioactive substance from leaking outside the cask.
[0003]
FIG. 11 is a diagram showing a structure of a lid portion of a conventional cask. As shown in FIG. 1, the cask 100 includes a trunk main body 110 and a lid 120. The trunk body 110 is a bottomed cylindrical shape having a cavity 111 for storing a radioactive substance such as a recycled fuel assembly, and is a cast product made of carbon steel or stainless steel. It has a sufficient thickness. The opening 112 above the cavity 111 has a stepped cross section in the axial direction of the body 110, and is provided with a step 113. In addition, 1'4 is a neutron shield for absorbing neutrons. The lid part 120 includes a primary lid 130 and a secondary lid 140. The primary lid 130 and the secondary lid 140 are disk-shaped members made of steel, and are provided with flange portions 131'41 on the outer periphery thereof. Further, the secondary lid 140 is provided with a neutron shield 142 for absorbing neutrons therein.
[0004]
When a radioactive material such as a recycled fuel assembly is stored in the cask 100, the radioactive material is stored in the cavity 111, and the primary lid 130 is attached in the opening 112 of the body 110, With the gasket 161 interposed between the portion 113 and the flange portion 131 of the primary lid 130, the primary lid 130 is fixed to the body 110 with bolts 151. Then, a secondary lid 140 is attached to the trunk main body 110 so as to cover the opening 112 of the trunk main body 110, that is, a gasket 162 is interposed between the upper surface 115 of the trunk main body 110 and the flange portion 141 of the secondary lid 140. Then, the secondary lid 140 is fixed to the trunk main body 110 with the bolt 152, thereby forming a closed structure of the cask 100. That is, in the related art, by interposing the gasket 161′62 as the sealing means between the trunk body 110 and the primary lid 130 and the secondary lid 140, the sealing reliability of the cask 100 as the radioactive substance storage container is improved. Have secured.
[0005]
Further, conventionally, in order to improve the reliability of the sealed structure of the radioactive substance storage container, a sealed structure in which a sealing member is attached by welding in addition to the sealing means has been proposed (for example, Patent Document 1). This sealing structure is provided between the trunk body 110 (the cask 10 in Patent Literature 1), the primary lid 130 (the inner lid 36 in Patent Literature 1), and the secondary lid 140 (the outer lid 38 in Patent Literature 1). Sealing is performed by sealing means (O-rings 42 and 52 in Patent Literature 1), and above a bolt 161 (bolt 40 in Patent Literature 1) for fixing the primary lid 130 and the trunk main body 110, that is, the trunk main body 110 and the primary lid. 130 is covered with a seal member (the seal ring 44 in Patent Document 1), and the seal member and the upper surface of the body main body 110 and the seal member and the upper surface of the primary lid 130 are welded (the seal weld portion 46). , 48).
[0006]
[Patent Document 1]
JP-A-61-76891 (FIG. 3)
[0007]
[Problems to be solved by the invention]
By the way, when the cask 100 falls or the like, the radioactive substance stored in the cavity 111 of the body 110 collides with the primary lid 130. Due to this collision, the primary lid 130 may be bent or displaced in the axial direction or the radial direction of the body 110 within the opening 112 of the body 110. At this time, when the primary lid 130 moves in the radial direction of the trunk main body 110, one end of the seal member is welded to the upper surface of the primary lid 130 in the hermetically sealed structure of the radioactive substance storage container according to Patent Document 1. Therefore, the seal member also attempts to move in the radial direction of the body 110 in the same manner. However, the other end of the seal member is welded to the upper surface of the body 110, so that the seal member cannot move. Therefore, a force is applied to a welded portion between the seal member and the body 110 or between the seal member and the primary lid 130 in a direction in which the welded portion is sheared, and the welded portion may be sheared. In other words, when the cask 100, which is a radioactive material storage container, falls or collides, the welded portion between the seal member and the body 110 or the seal member and the primary lid 130, which is the inner lid, is sheared, so that the radioactive material storage container is closed. Reliability may be reduced.
[0008]
Also, after storing a radioactive material such as a recycled fuel assembly in the cavity 111 of the trunk body 110, the sealing operation of the cask 100 for fixing the primary lid 130 and the secondary lid 140 to the trunk body 110 is performed under high radiation. Work. Therefore, the operation time for inserting the seal member into the opening 112 of the body 110 and the operation time for welding the seal member can be reduced, that is, the operation time for sealing the radioactive substance storage container can be shortened, and the safety of the worker can be improved. It is necessary to.
[0009]
Then, this invention was made in view of the above, and while improving the reliability of sealing of a radioactive material storage container, when the radioactive material storage container falls or collides, the sealing of this radioactive material storage container is performed. An object of the present invention is to provide a sealed structure of a radioactive substance storage container which can maintain reliability or at least one of shortening a sealing work time and improving worker safety.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, at least a recycled fuel assembly and other radioactive materials are housed in a cavity, a trunk body provided with a neutron shield around the cavity, and a lid attached to the trunk body. In the hermetically sealed structure of the radioactive substance storage container comprising a portion, and a sealing means for sealing the trunk body and the lid portion, the lid portion is attached to the inside of the opening above the cavity of the trunk body, and attached to the outside of the inner lid. A seal member different from sealing means having flexibility at least in the radial direction of the trunk body is provided between the trunk body and the inner lid by welding.
[0011]
According to the present invention, since a sealing member different from the sealing means having flexibility at least in the radial direction of the trunk body is attached by welding between the trunk body and the inner lid, that is, the sealing means and the sealing member Since the opening of the trunk body is closed by the above, the reliability of sealing the radioactive substance storage container can be improved. Further, even if the sealing member moves in the radial direction of the trunk body when the radioactive substance storage container falls or collides, the sealing member is bent, thereby welding the sealing member to the trunk body or the sealing member to the inner lid. The amount of displacement of the portion can be reduced, the possibility that the welded portion is sheared can be reduced, and the reliability of sealing the radioactive substance storage container can be maintained. Here, as the sealing means, a means to be sealed by the trunk body and the lid itself (for example, a labyrinth structure constituted by forming a contact surface between the trunk body and the lid in a step shape) or a trunk body and the lid (For example, a gasket or an O-ring) and the like (hereinafter the same).
[0012]
According to the present invention, in the hermetically sealed structure of the radioactive substance storage container according to claim 1, the inner lid has a flange portion abutting on a step provided on the outer peripheral surface at the opening, and the seal member has It is inserted into a ring-shaped space formed by the outer peripheral surface of the inner lid, the upper surface of the flange portion, and the inner peripheral surface of the opening of the trunk main body, and is attached to the trunk main body and the inner lid by welding. It is characterized by.
[0013]
According to this invention, the inner lid has a flange portion on the outer peripheral surface that abuts on a step provided in the opening, and the seal member has the outer peripheral surface of the inner lid, the upper surface of the flange portion, and the opening of the trunk body. Is inserted into a ring-shaped space formed by the inner peripheral surface of the body and is welded to the body and the inner lid, that is, the opening of the body is sealed by the sealing means and the sealing member. Therefore, the reliability of sealing the radioactive substance storage container can be improved. Also, even if the seal member moves in the radial direction of the trunk body when the radioactive substance storage container falls or collides, the seal member inserted into the ring-shaped space bends and the seal member and the trunk body or the seal are bent. The amount of displacement of the welded portion between the member and the inner lid can be reduced, the possibility of the welded portion being sheared can be reduced, and the reliability of the sealing of the radioactive substance storage container can be maintained.
[0014]
According to the present invention, in the hermetically sealed structure for a radioactive substance storage container according to the second aspect, the seal member has an arm extending in the axial direction of the trunk main body at at least one of both ends of the seal member. And the tip of the arm is welded to the trunk body and / or the inner lid.
[0015]
According to the present invention, the seal member has an arm extending in the axial direction of the trunk main body at at least one of both end portions of the seal member, and the distal end of the arm is provided at the trunk main body and / or the inner lid. Therefore, in addition to the operation and effect of the invention according to claim 2, when the seal member is welded, the welded portion between the distal end portion of the arm portion of the seal member and the trunk body and / or the inner lid is formed. It can be seen from the opening of the trunk body to which the lid is attached, the welding work of the seal member can be easily performed, and the sealing work time of the radioactive substance storage container can be shortened. Also, when the seal member is removed to open the radioactive substance storage container, the welded portion between the seal member and the trunk body and / or the inner lid can be visually recognized from the opening of the trunk body to which the inner lid is attached. Therefore, the welded portion can be easily sheared, the sealing member can be easily opened, the sealing work time of the radioactive material storage container can be shortened, and the safety of workers can be improved. it can.
[0016]
Further, in the present invention, at least a recycle fuel assembly and other radioactive materials are stored in the cavity, and a trunk body provided with a neutron shield around the cavity; a lid attached to the trunk body; And a sealing means for sealing the radioactive substance storage container, comprising: an inner lid attached to an opening above the cavity of the trunk main body; and an outer lid attached to the outside of the inner lid. A seal member different from the sealing means having flexibility at least in the radial direction of the trunk main body is attached between the outer lid and the inner lid by welding.
[0017]
According to the present invention, since a sealing member different from the sealing means having flexibility at least in the radial direction of the trunk body is attached between the outer lid and the inner lid by welding, that is, the sealing means and the sealing member Since the opening of the trunk body is closed by the above, the reliability of sealing the radioactive substance storage container can be improved. Further, even when the seal member moves in the radial direction of the trunk body when the radioactive substance storage container falls or collides, the displacement of the welded portion between the seal member and the trunk body can be reduced by bending the seal member. The possibility that the welded portion is sheared can be reduced, and the reliability of the hermetic seal of the radioactive substance storage container can be maintained. Furthermore, the welding line between the seal member and the body of the body has a single welding line, so that the welding operation time of the sealing member can be shortened, the sealing operation time of the radioactive material storage container can be shortened, and the safety of workers can be improved. Can be improved.
[0018]
Further, in the present invention, in the sealed structure of the radioactive substance storage container according to claim 4, the seal member is inserted into an opening of the trunk body to which the inner lid is attached, and is attached to the trunk body by welding. It is characterized by having been done.
[0019]
According to the present invention, since the seal member is inserted into the opening of the trunk body to which the inner lid is attached and is attached to the trunk body by welding, that is, the trunk body is formed by the sealing means and the seal member. Since the opening is closed, the reliability of the sealing of the radioactive substance storage container can be improved. Further, even when the seal member moves in the radial direction of the trunk body when the radioactive substance storage container falls or collides, the displacement of the welded portion between the seal member and the trunk body can be reduced by bending the seal member. The possibility that the welded portion is sheared can be reduced, and the reliability of the hermetic seal of the radioactive substance storage container can be maintained. Furthermore, the welding line of the welding portion between the sealing member and the opening of the trunk main body becomes one, so that the welding operation time of the sealing member can be shortened, the sealing operation time of the radioactive substance storage container can be shortened, and the safety of workers can be reduced. Performance can be improved.
[0020]
According to the present invention, in the sealed structure of the radioactive substance storage container according to the fifth aspect, the seal member has an arm extending at an end of the seal member in the axial direction of the trunk body, and a tip of the arm. The part is welded to the trunk body.
[0021]
According to this invention, the seal member has an arm portion extending in the axial direction of the trunk body at the end of the seal member, and the tip end of the arm portion is welded to the trunk body. In addition to the effects of the invention, when welding the seal member, the tip of the arm of the seal member and the welded portion of the trunk main body can be visually recognized from the opening of the trunk main body to which the inner lid is attached, The welding operation of the seal member can be easily performed, and the sealing operation time of the radioactive substance storage container can be shortened. Further, when the seal member is removed to open the radioactive substance storage container, the welded portion between the seal member and the trunk body can be visually recognized from the opening of the trunk body to which the inner lid is attached. Can be easily sheared, the opening operation of the seal member can be easily performed, the sealing operation time of the radioactive substance storage container can be further reduced, and the safety of the operator can be further improved.
[0022]
In this invention, in the sealed structure of the radioactive substance storage container according to claim 3 or 6, the arm portion is provided on the inner peripheral surface of the opening of the trunk main body and / or the outer peripheral surface of the inner lid in the radial direction of the trunk main body. The contact is made in a state of being urged to.
[0023]
According to this invention, since the arm portion is in contact with the inner peripheral surface of the opening of the trunk main body and / or the outer peripheral surface of the inner lid in a state of being urged in the radial direction of the trunk main body, the seal member is formed into a ring. When the seal member is inserted into the open space or the opening of the body, the inserted position of the inserted seal member can be maintained. This eliminates the need for holding means for holding the seal member at the insertion position when welding the seal member, thereby facilitating welding of the seal member and shortening the sealing work time of the radioactive substance storage container. And the safety of the worker can be further improved.
[0024]
According to the present invention, in the hermetically sealed structure for a radioactive substance storage container according to any one of claims 1 to 7, the seal member has a projecting portion projecting in an axial direction of the trunk main body.
[0025]
According to the present invention, since the seal member has the protruding portion that protrudes in the axial direction of the trunk main body, even if the seal member moves in the radial direction of the trunk main body when the radioactive substance storage container falls or collides, the seal member is sealed. The member, in particular, the protrusion of the seal member is bent, the displacement of the welded portion between the seal member and the body or the seal member and the inner lid can be further reduced, and the possibility of the welded portion being sheared can be further reduced. The sealing reliability of the containment vessel can be further maintained.
[0026]
According to the present invention, in the hermetically sealed structure for a radioactive substance storage container according to any one of claims 1 to 8, a ring-shaped welding projection is provided on a body main body and / or an inner lid to which a seal member is welded. It is characterized by having.
[0027]
According to the present invention, since the ring-shaped welding projection is provided on the trunk body and / or the inner lid to which the seal member is welded, the seal member is provided on the trunk body and / or the inner lid as compared with the trunk body or the primary lid itself. The heat capacity of the welding point for welding the seal can be reduced, that is, the heat capacity can be approximated to the heat capacity of the seal member, the seal member can be easily welded, and the sealing work time of the radioactive substance storage container can be further shortened, Can be further improved. Here, the welding protrusion may be provided by cutting the trunk body or the inner lid, or a ring-shaped member may be attached to the trunk body or the inner lid.
[0028]
Further, according to the present invention, a radioactive material including a recycle fuel assembly and other radioactive materials in a cavity, a trunk body provided with a neutron shield around the cavity, and a lid attached to the trunk body In the closed structure of the containment vessel, an outer cylinder that covers a neutron shield provided by covering the lid with a sealing member different from sealing means having flexibility at least in the radial direction of the trunk body, and an end of the sealing member provided on the trunk body. It is characterized by being attached to by welding.
[0029]
According to the present invention, at least an outer cylinder that covers the neutron shield provided at the end of the torso body by covering the lid with a sealing member different from the sealing means having flexibility at least in the radial direction of the torso main body and providing the end of the seal member to the torso main body. Since the attachment is made by welding, that is, since the opening of the trunk body is sealed by the sealing means and the sealing member, the reliability of the sealing of the radioactive substance storage container can be improved. Further, even if the seal member moves in the radial direction of the trunk body when the radioactive substance storage container falls or collides, the displacement of the welded portion between the seal member and the outer cylinder of the trunk body is caused by bending of the seal member. The amount can be reduced, the possibility that the welded portion is sheared can be reduced, and the reliability of sealing the radioactive substance storage container can be maintained. Furthermore, since the sealing member is not already attached to the outer cylinder of the trunk body by welding after the trunk body and the lid are hermetically sealed by the sealing means, the operation is not under high radiation, so that the safety of the worker can be improved.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited by the embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.
[0031]
(First embodiment)
FIG. 1 is an axial cross-sectional view of the radioactive substance storage container of the first embodiment. Here, the radioactive substance storage container includes a cask, a canister, and the like. As shown in FIG. 1, the radioactive substance storage container 1 includes a body 2 and a lid 3. The body 2 has a hollow cylindrical shape having an opening 2a, and a disc-shaped bottom plate 4 is attached to the bottom of the body 2 by welding. A not-shown basket or the like for loading a radioactive substance R such as a recycled fuel assembly is accommodated in a cavity 2b which is a space formed by the hollow portion of the body 2 and the bottom plate 4. Here, the trunk body 2 and the bottom plate 4 are forged products made of carbon steel, and have a thickness sufficient to exhibit a γ-ray shielding function. It is to be noted that a metal billet is charged into a container having an internal shape corresponding to the outer shape of the trunk body 2, and the metal billet is hot-expanded and formed by a punch having an outer diameter corresponding to the inner diameter of the trunk body 2. The body 2 and the bottom plate 4 may be integrally formed by molding, or may be manufactured by casting.
[0032]
Further, an outer cylinder 5 is attached to the outer peripheral portion of the body 2 via a plurality of heat transfer fins formed of a heat conductive material such as an aluminum plate or a copper plate (not shown). The decay heat generated from the radioactive substance R stored in the cavity 2 b is transmitted to the heat transfer fins through the body 2. The decay heat from the radioactive substance R transmitted to the heat transfer fins is transmitted to the outer cylinder 5 and then released from the surface of the outer cylinder 5 to the atmosphere. A space between the outer cylinder 5 and the body 2 is filled with a neutron absorber 6 such as resin, polyurethane, or silicon, which is a polymer material containing a large amount of hydrogen. The neutron absorber 6 is similarly sealed in the bottom plate 4.
[0033]
As shown in FIG. 1, the lid 3 includes a primary lid 7 as an inner lid and a secondary lid 8 as an outer lid. The primary lid 7 and the secondary lid 8 have a disk shape made of carbon steel or stainless steel that blocks γ rays. The primary lid 7 is provided with a flange portion 7a on an outer peripheral portion thereof, which is in contact with a step 2c provided between the opening 2a of the body 2 and the cavity 2b. On the other hand, the secondary lid 8 is provided with a flange portion 8a at the outer peripheral portion thereof, which is in contact with the upper surface 2d of the trunk body 2, and the neutron absorber 6 is sealed therein. The primary lid 7 and the secondary lid 8 are fixed to the body 2 with a plurality of bolts 9a and 9b, respectively. Reference numeral 8b denotes a load projection that is a load transmission mechanism for sharing the load applied to the primary lid 7 to the secondary lid 8 when the radioactive substance storage container 1 falls or collides.
[0034]
The hermetically sealed structure of the radioactive substance storage container 1 includes gaskets 10a and 10b as sealing means and a seal member 12. The gaskets 10a and 10b are made of ring-shaped metal, and are interposed between the trunk body 2 and the primary lid 7 and between the trunk body 2 and the secondary lid 8, respectively.
[0035]
2A and 2B are diagrams illustrating a configuration example of a seal member according to the first embodiment. FIG. 2A is an enlarged view of a part A of FIG. 1A, FIG. 2B is a plan view of the seal member, and FIG. FIG. 3C is an axial sectional view of the seal member before being inserted into the space. As shown in FIG. 1B, the seal member 12 is ring-shaped and made of carbon steel or stainless steel. As shown in FIG. 1A, the ring-shaped seal member 12 is located above the flange 7a of the primary lid 7, that is, the outer peripheral surface of the primary lid 7 and the upper surface of the flange 7a (including the upper surface of the bolt 9a). ) And the inner peripheral surface of the opening 2 a of the body 2. The seal member 12 is provided with a protruding portion 12a above the body 2 in the axial direction and protruding portions 12b and 12c below the body 2 in the axial direction. At both ends of the seal member 12, arm portions 12d and 12e extending in the axial direction of the trunk main body 2 (upward in FIG. 2B) are provided. That is, the seal member 12 has a shape in which the M-shape is inverted when the axial cross-sectional shape is inserted into the space portion 11.
[0036]
As shown in FIG. 3C, the shape of the seal member 12 before it is inserted into the space 11 is such that the width d1 of the distal end portions 12f and 12g of the arms 12d and 12e is the space where the seal member 12 is inserted. 11 is wider than the width d2, that is, its axial cross-sectional shape is W-shaped. Therefore, even when the width d1 of the space portion 11 is not uniform due to manufacturing tolerances of the trunk body 2 and the primary lid 7, the protrusions 12a, 12b, and 12c of the seal member 12 bend, and the seal member 12 is moved to the space portion. 11 can be easily inserted. Further, the arms 12d and 12e of the seal member 12 inserted into the space 11 come into contact with the inner peripheral surface of the opening 2a of the trunk body 2 and the outer peripheral surface of the primary lid 7 in a urged state. Accordingly, the sealing member 12 can maintain the insertion position inserted into the space portion 11, and does not require holding means for holding the sealing member 12 at the insertion position when welding the sealing member 12. The welding work of the member 12 can be easily performed. In addition, the distal ends 12f and 12g of the seal member 12 inserted into the space 11 can maintain the state in which the inner peripheral surface of the opening 2a of the trunk body 2 and the outer peripheral surface of the primary lid 7 are in contact with each other. Can be easily performed. In addition, the distal ends 12f and 12g of the arms 12d and 12e can be visually recognized from the opening 2a of the trunk body 2 to which the primary lid 7 is attached, and the welding of the seal member 12 can be easily performed. Furthermore, since the seal member 12 is ring-shaped and can be easily inserted into the space portion 11, high precision is not required for manufacturing, and the manufacturing cost of the seal member 12 can be reduced.
[0037]
On the inner peripheral surface of the opening 2a of the trunk body 2 and the outer peripheral surface of the primary cover 7, welding projections 2e and 7b are formed at positions where the tips 12f and 12g of the arms 12d and 12e are in contact with each other. Provided by The seal member 12 is formed by welding the distal end 12f of the arm 12d of the seal member 12, the welding projection 2e of the trunk body 2, and the distal end 12g of the arm 12e to the welding projection 7b. The member 12 is mounted between the trunk main body 2 and the primary lid 7. The welding of the seal member 12 is performed by, for example, TIG welding, laser welding, or the like. Further, since the welding projections 2e of the trunk main body 2 and the welding projections 7b of the primary lid 7 have smaller heat capacities than the trunk main body 2 or the primary lid 7 itself, that is, the welding projections 2e of the distal ends 12f and 12g of the seal member 12 are formed. Since the heat capacity is approached, the sealing member 12 can be easily welded.
[0038]
When the primary lid 7 moves in the radial direction of the trunk main body 2 by bending or shifting the primary lid 7, the width d1 of the space 11 into which the sealing member 12 is inserted shown in FIG. (Longer or shorter). The widths of the arms 12d and 12e of the seal member 12 are displaced in accordance with the displacement of the width d1 of the space portion 11, but the protrusions 12a, 12b and 12c of the seal member 12 bend, and the displacement amount is increased. Is absorbed. Therefore, the displacement of the welded portion S between the seal member 12, the trunk body 2 and the primary lid 7 can be reduced. Thereby, even if the sealing member 12 moves in the radial direction of the trunk body 2 when the radioactive substance storage container 1 falls or collides, the possibility that the welded portion is sheared can be reduced.
[0039]
The lengths of the arms 12d and 12e of the seal member 12 may be the same as shown in FIG. Accordingly, when the radioactive substance storage container 1 falls or collides, the primary lid 7 is displaced following the displacement of the width of the space portion 11 due to the radial movement of the trunk body 2. By bending the portions 12a, 12b, and 12c, the displacement can be absorbed, and the displacement of the welded portion S between the seal member 12, the body 2, and the primary lid 7 can be made uniform. The displacement of any of the portions S can be prevented from increasing, and the possibility that the welded portion is sheared can be further reduced. Thereby, even if the sealing member 12 moves in the radial direction of the trunk main body 2 when the radioactive substance storage container 1 falls or collides, the reliability of the sealing of the radioactive substance storage container 1 can be further maintained. In addition, when the primary lid 7 moves in a small amount in the radial direction of the body 2, as shown in FIG. , Or a U-shape without the protrusions 12a, 12b, 12c. In this case, the shape before insertion into the space 11 of the seal member 12 is such that the width of the distal ends 12f and 12g of the arms 12d and 12e is wider than the width of the space 11 into which the seal member 12 is inserted. It is preferable that
[0040]
By making the radioactive substance storage container 1 have the above-described sealed structure, the sealing reliability of the radioactive substance storage container 1 can be improved, and when the radioactive substance storage container 1 falls or collides, the sealing member 12 is formed. Can be maintained in the radial direction of the trunk body 2, the reliability of the sealing of the radioactive substance storage container 1 can be maintained.
[0041]
FIG. 4 is a diagram illustrating another configuration example of the seal member. As shown in FIG. 1A, the seal member 12 'is inserted into the ring-shaped space 11 like the seal member 12. The seal member 12 ′ is provided with a protruding portion 12 b in the vicinity of the trunk body 2 below the trunk body 2 in the axial direction. Further, an arm portion 12d is provided at an end of the seal member 12 'on the side of the trunk main body 2 extending in the axial direction of the trunk main body 2 (upward in FIG. 2A). The inner peripheral surface of the opening 2a of the trunk body 2 and the outer peripheral surface of the primary lid 7 are located at positions where the tip 12f of the arm 12d of the seal member 12 'and the end 12h on the primary lid 7 side respectively contact each other. Welding projections 2e and 7b 'are provided by cutting or the like. The seal member 12 ′ is formed by welding the tip 12 f of the arm 12 d of the seal member 12 ′ to the welding projection 2 e of the trunk body 2 and the end 12 h to the welding projection 7 b. It is mounted between the primary lid 7.
[0042]
Since the end 12h of the seal member 12 'is not inserted into the opening 11, when the seal member 12' is inserted into the opening 11, the distal end 12f of the arm 12d and the welding projection 2e of the trunk body 2 are formed. The insertion position of the seal member 12 ′ in the space 11 can be set only by adjusting the position of the seal member 12 ′. The welding of the seal member 12 ′ is preferably performed from the tip 12 f of the arm 12 d and the welding projection 2 e of the trunk body 2. Thereby, the seal member 12 ′ can be held at the insertion position of the space 11. The height of the welding projection 7b 'is set so that the upper surface of the end 12h of the seal member 12' welded to the upper surface does not exceed the upper surface of the primary lid 7. This is because when the primary lid 7 moves in the axial direction of the body 2 and comes into contact with the secondary lid 8, the welded portion S between the end 12 h of the seal member 12 ′ and the welding projection 7 b ′ is secondary. This is to prevent the lower surface of the lid 8 from being touched and damaged.
[0043]
The sealing structure of the radioactive substance storage container 1 is different from that of the first embodiment in that a sealing member 12 ′ is inserted into the space 11 instead of the sealing member 12, and the sealing member 12 ′ is welded to the body 2 and the primary lid 7. And the radioactive substance storage container 1 shown in FIG. When the radioactive substance storage container 1 falls or collides, the primary lid 7 moves in the radial direction of the body 2, and the width between the end 12 h of the seal member 12 ′ and the arm 12 d is equal to the width of the space 11. Even if the displacement follows the displacement, the protrusion 12b of the seal member 12 'bends to absorb the displacement. Therefore, the displacement of the welded portion S can be reduced for any of the welded portions S between the seal member 12 ′, the trunk body 2, and the primary lid. Thereby, even if the sealing member 12 'moves in the radial direction of the trunk body 2 when the radioactive substance storage container 1 falls or collides, there is no possibility that the welded portion S is sheared. Therefore, by making the radioactive substance storage container 1 have the above-described sealed structure, the sealing reliability of the radioactive substance storage container 1 can be improved, and the radioactive substance storage container 1 can be sealed when it falls or collides. Even if the member 12 ′ moves in the radial direction of the trunk main body 2, it is possible to maintain the sealing reliability of the radioactive substance storage container 1.
[0044]
Here, the hermetically sealed state of the radioactive material storage container 1 is performed by monitoring the pressure between the primary lid 7 and the secondary lid 8, but a certain amount of volume is required to accurately detect this pressure. It is. In the seal member 12 ', the volume of the space between the lower portion, that is, the lower surface of the seal member 12' and the upper surface of the flange 7a of the primary lid 7 can be increased. The sealed state of the storage container 1 can be monitored appropriately. As shown in FIG. 3B, the primary lid 7 is welded directly to the primary lid 7 at the end on the primary lid 7 side without providing the welding projection 7b 'of the primary lid 7. Is also good. Thereby, the welded portion between the seal member 12 'and the primary lid 7 can be made strong.
[0045]
In the above-described embodiment, the closed structure of the radioactive substance storage container 1 in which the lid portion 3 includes the primary lid 7 as the inner lid and the secondary lid 8 as the outer lid has been described, but the present invention is not limited to this. However, the present invention can also be used for a radioactive substance storage container having an inner lid having a double structure. FIG. 5 is a diagram showing a configuration example of a sealed structure of a radioactive substance storage container having a double inner lid. This radioactive substance storage container 1 ′ differs from the radioactive substance storage container 1 shown in FIG. 1 in that the inner lid has a double structure of a primary lid 7 and a support lid 13. The lid 3 of the radioactive substance storage container 1 ′ includes a primary lid 7, a secondary lid 8, and a support lid 13. The support lid 13 has a disk shape made of carbon steel or stainless steel that shields γ rays similarly to the primary lid 7 and the secondary lid 8, and has a stepped portion 2 c of an opening 2 a of the body 2 around its outer periphery. Is provided with a flange portion 13a which abuts on a lower portion, that is, a step portion 2f provided on the cavity 2b side. The support lid 13 is fixed to the trunk main body 2 with a plurality of bolts 9c so as to provide a gap 2g with the primary lid 7.
[0046]
The sealed structure of the radioactive substance storage container 1 'is interposed between the trunk main body 2 and the primary lid 7 and between the trunk main body 2 and the secondary lid similarly to the radioactive substance storage container 1 shown in FIG. It comprises gaskets 10a and 10b as sealing means, and a seal member 12 inserted into the space 11 and welded to the body 2 and the primary lid 7. The radioactive substance storage container 1 ′ shown in FIG. 5 falls or collides, and the radioactive substance (not shown) stored in the cavity 2 b of the trunk main body 2 collides with the support lid 13. Even if the body 2 is bent or displaced in the axial direction or radial direction in the portion 2a, the load from the support lid 13 is not shared by the primary lid 7 due to the gap 2g. That is, even if the support lid 13 moves in the radial direction of the trunk body 2, the primary lid 7 moves following the movement of the support lid 13, so that unless the primary lid 7 is bent or shifted by its own weight, The seal member 12 inserted into and welded to the space 11 of the primary lid 7 does not cause displacement of the trunk body 2 in the radial direction. Therefore, by making the radioactive substance storage container 1 ′ a sealed structure as described above, the sealing reliability of the radioactive substance storage container 1 ′ can be improved, and the radioactive substance storage container 1 ′ has dropped or collided. In this case, even if the support lid 13 moves, the sealing member 12 does not move in the radial direction of the trunk main body 2, so that the reliability of sealing the radioactive substance storage container 1 ′ can be further maintained.
[0047]
As shown in FIG. 6, the seal member 12 is provided between the trunk body 2 and the support lid 13 as the inner lid, that is, the outer peripheral surface of the support lid 13 and the upper surface of the flange portion 13a (including the upper surface of the bolt 9c). It may be inserted into a ring-shaped space portion 14 formed between the inner peripheral surface of the opening 2a of the trunk main body 2 and attached by welding. The sealed structure of the radioactive substance storage container 1 'is interposed between the trunk main body 2 and the primary lid 7 and between the trunk main body 2 and the secondary lid similarly to the radioactive substance storage container 1 shown in FIG. It comprises gaskets 10a and 10b, which are sealing means, and a seal member 12 inserted into the space 14 and welded to the body 2 and the support lid 13. When the radioactive substance storage container 1 ′ falls or collides, the support lid 13 moves in the radial direction of the body 2, and the width of the arms 12 d and 12 e of the seal member 12 follows the displacement of the width of the space 14. Even when the seal member 12 is displaced, the protrusions 12a, 12b, and 12c of the seal member 12 bend, thereby absorbing the displacement. Therefore, the displacement of the welded portion S can be reduced in any of the welded portions S between the seal member 12, the body 2 and the support lid 13. Thereby, even if the sealing member 12 moves in the radial direction of the trunk body 2 when the radioactive substance storage container 1 ′ falls or collides, the possibility that the welded portion S is sheared can be reduced. Therefore, by making the radioactive substance storage container 1 ′ a sealed structure as described above, the sealing reliability of the radioactive substance storage container 1 ′ can be improved, and the radioactive substance storage container 1 ′ has fallen or collided. In this case, even if the seal member 12 moves in the radial direction of the trunk main body 2, the reliability of sealing the radioactive substance storage container 1 'can be maintained.
[0048]
Here, as shown in FIG. 3A, the seal members 12 of the radioactive substance storage containers 1 'and 1' have the same length as the arm portions 12d and 12e as shown in FIG. The shape which does not have the protruding portions 12a, 12b and 12c as shown in FIG. Further, a seal member 12 ′ may be used instead of the seal member 12.
[0049]
(Second embodiment)
FIG. 7 is an axial cross-sectional view of the radioactive substance storage container of the second embodiment. The radioactive substance storage container 20 of the second embodiment shown in FIG. 7 has the same basic configuration as the radioactive substance storage container 1 of the first embodiment shown in FIG. This radioactive substance storage container 20 differs from the radioactive substance storage container 1 shown in FIG. 1 in that a seal member 15 is provided between a primary lid 7 as an inner lid and a secondary lid 8 as an outer lid. It is in. The hermetically sealed structure of the radioactive substance storage container 30 includes gaskets 10a and 10b as sealing means and a seal member 15.
[0050]
8A and 8B are diagrams illustrating a configuration example of a seal member according to the second embodiment. FIG. 8A is an enlarged view of a part B of FIG. 1A, FIG. 8B is a plan view of the seal member, and FIG. FIG. 3C is an axial sectional view of the seal member before being inserted into the space. As shown in FIG. 2B, the sealing member 15 is disk-shaped and made of carbon steel or stainless steel. As shown in FIG. 1A, the disc-shaped sealing member 15 has an opening 2a between the primary lid 7 and the secondary lid 8 and covers the upper surface of the primary lid 7 so as to cover the upper surface of the primary lid 7. Has been inserted. The seal member 15 is provided with a protruding portion 15a near the end thereof above the body 2 in the axial direction. Further, the end of the seal member 15 is provided with an arm 15b extending in the axial direction of the trunk main body 2 (upward in FIG. 2B).
[0051]
As shown in FIG. 3C, the shape before the insertion of the seal member 15 into the opening 2a is such that the width d3 of the distal end 15c of the arm 15b is equal to the width d4 of the opening 2a into which the seal member 15 is inserted. It has a wider shape. Therefore, even when the width d4 of the distal end portion 15c is not uniform due to the manufacturing tolerance of the seal member 15, the protrusion 15a of the seal member 15 bends, so that the seal member 15 can be easily inserted into the opening 2a. Can be. The arm 15b of the seal member 15 inserted into the opening 2a comes into contact with the inner peripheral surface of the opening 2a of the body 2 while being urged. Thereby, the sealing member 15 can maintain the insertion position inserted into the opening 2a, and does not require a holding unit for holding the sealing member 15 at the insertion position when welding the sealing member 15, and the sealing member 15 can be sealed. The welding work of the member 15 can be easily performed. In addition, the distal end portion 15c of the seal member 15 inserted into the opening 2a can maintain the state of being in contact with the inner peripheral surface of the opening 2a of the trunk body 2, so that welding work of the seal member 15 can be easily performed. it can. Further, the distal end portion 15c of the arm portion 15b can be visually recognized from the opening 2a of the trunk main body 2, and the welding work of the seal member 15 can be easily performed.
[0052]
On the inner peripheral surface of the opening 2a of the trunk body 2, a welding projection 2e is provided by cutting or the like at a position where the tip 15c of the arm 15b contacts. The seal member 15 is attached between the primary cover 7 and the secondary cover 8 by welding the tip 15c of the arm portion 15b of the seal member 15 and the welding protrusion 2e of the trunk body 2. . The welding of the seal member 15 is performed by, for example, TIG welding, laser welding, or the like. Further, since the welding protrusion 2e of the trunk body 2 has a smaller heat capacity than the trunk body 2 itself, that is, approaches the heat capacity of the distal end portion 15c of the seal member 15, the welding of the seal member 15 can be easily performed. it can. Furthermore, since the welding portion S between the sealing member 15 and the body 2 is one place, that is, the welding line S has one welding line, the welding operation time of the sealing member 15 can be reduced. In addition, since the welded portion S is located at one location, the work of shearing the welded portion S of the seal member 15 and removing the seal member 15 from the opening 2a of the body 2 can be performed in a short time.
[0053]
When the radioactive substance storage container 20 falls or collides, the primary lid 7 may be displaced or displaced in the axial direction or the radial direction of the body 2 in some cases. When the primary cover 7 moves only in the radial direction of the body 2, the sealing member 15 is not fixed to the primary cover 7. The amount of displacement in the direction is small. When the primary lid 7 moves in the axial direction and the radial direction of the body 2, first, the primary lid 7 collides with the load projection 8 of the secondary lid 8 via the seal member 15. At this time, since the seal member 15 is in close contact between the primary cover 7 and the secondary cover 8, the amount of displacement of the seal member 15 in the radial direction of the trunk body follows the amount of displacement when the primary cover 7 moves. I do. In any of the above cases, the protrusion 15a of the seal member 15 bends to absorb the displacement. Therefore, the displacement of the welded portion S between the seal member 15 and the body 2 can be reduced. Thereby, even if the sealing member 15 moves in the radial direction of the trunk body 2 when the radioactive substance storage container 20 falls or collides, the possibility that the welded portion S is sheared can be reduced.
[0054]
In the above-described embodiment, when the radioactive substance storage container 20 falls or collides, the load on the primary lid 7 is shared by the secondary lid 8 so that the secondary lid 8 serves as a load transmitting mechanism. However, a load projection 15d may be provided on the upper surface of the seal member 15, as shown in FIG. Further, as shown in FIG. 9B, the load projection 15 d may be provided below the seal member 15.
[0055]
By making the radioactive substance storage container 20 have the above-mentioned sealed structure, the sealing reliability of the radioactive substance storage container 20 can be improved, and when the radioactive substance storage container 20 falls or collides, the sealing member 12 is formed. Can be maintained in the radial direction of the trunk body 2, the sealing reliability of the radioactive substance storage container 20 can be maintained.
[0056]
(Third embodiment)
FIG. 10 is a sectional view of a main part of the radioactive substance storage container of the third embodiment. The radioactive substance storage container 30 of the third embodiment shown in FIG. 10 has the same basic configuration as the radioactive substance storage container 1 of the first embodiment shown in FIG. This radioactive substance storage container 30 differs from the radioactive substance storage container 1 shown in FIG. 1 in that a seal member 16 that covers the lid 3 is provided. The hermetically sealed structure of the radioactive substance storage container 30 includes gaskets 10a and 10b, which are sealing means, and a seal member 16.
[0057]
The sealing member 16 is composed of a disk portion 16a and an outer peripheral portion 16b, and has a concave axial sectional shape, and is made of carbon steel or stainless steel. The sealing member 16 is covered so as to cover the outer peripheral surface of the lid 3, that is, the secondary lid 8, with the primary lid 7 and the secondary lid 8 attached to the radioactive substance storage container 30. At the lower end of the outer peripheral portion 16b of the seal member 16, an arm portion 16c extending in the radial direction of the trunk main body 2 is provided. The sealing member 16 is attached so as to cover the lid 3 by welding the distal end 16 d of the arm 16 c of the sealing member 16 and the outer cylinder 5. The radioactive substance storage container 30 to which the seal member 16 is attached is attached such that a buffer (not shown) covers the cover 3 during transportation, that is, covers the seal member 16. Here, since the heat capacity of the outer cylinder 5 is smaller than that of the body 2 itself, that is, the heat capacity of the outer cylinder 5 approaches the heat capacity of the distal end portion 16c of the seal member 16, so that the seal member 16 can be easily welded. Furthermore, since the welding portion S between the seal member 16 and the outer cylinder 5 is one place, that is, the welding line S has one welding line, the welding operation time of the seal member 16 can be reduced. Further, since the welded portion S is located at one location, the work of removing the seal member 16 from the outer cylinder 5 provided on the body 2 can be performed in a short time by shearing the welded portion S. Further, the tip portion 16d of the arm portion 16c can be visually recognized from above the radioactive substance storage container 30, and welding work of the seal member 16 can be easily performed.
[0058]
When the primary lid 7 moves in the axial direction and the radial direction of the trunk body 2 due to the primary lid 7 flexing or shifting when the radioactive substance storage container 30 falls or collides, first, the primary lid 7 is It collides with the load projection 8 of the secondary lid 8 via the seal member 15. The load on the primary cover 7 is shared by the secondary cover 8 when the primary cover 7 collides with the secondary cover 8, so that the secondary cover 8 also moves in the axial direction and the radial direction of the body 2. Since the outer peripheral portion 16b of the seal member 16 is in close contact with the outer peripheral surface of the secondary lid 8, the amount of displacement of the seal member 16 in the radial direction of the body 2 is equal to the amount of displacement when the secondary lid 8 moves. Follow. The seal member 16 absorbs the above-mentioned amount of displacement by bending the joint 16e between the outer peripheral portion 16b of the seal member 16 and the arm 16c. Therefore, the displacement of the welded portion S between the seal member 16 and the outer cylinder 5 can be reduced. Thereby, even if the sealing member 16 moves in the radial direction of the trunk body 2 when the radioactive substance storage container 20 falls or collides, the possibility that the welded portion S is sheared can be reduced.
[0059]
By making the radioactive substance storage container 30 have the above-described sealed structure, the reliability of the sealing of the radioactive substance storage container 30 can be improved, and when the radioactive substance storage container 30 falls or collides, the sealing member 16 is used. Can be maintained in the radial direction of the trunk main body 2, the sealing reliability of the radioactive substance storage container 30 can be maintained.
[0060]
【The invention's effect】
As described above, according to the first and second aspects of the invention, a sealing member different from the sealing means having flexibility at least in the radial direction of the trunk main body is provided between the trunk main body and the inner lid. Since it is attached by welding, that is, since the opening of the trunk body is sealed by the sealing means and the sealing member, the reliability of the sealing of the radioactive substance storage container can be improved. Further, even if the sealing member moves in the radial direction of the trunk body when the radioactive substance storage container falls or collides, the sealing member is bent, thereby welding the sealing member to the trunk body or the sealing member to the inner lid. The amount of displacement of the portion can be reduced, the possibility that the welded portion is sheared can be reduced, and the reliability of sealing the radioactive substance storage container can be maintained.
[0061]
According to the third aspect of the present invention, the seal member has an arm extending in the axial direction of the trunk main body at at least one of both ends of the seal member, and the tip of the arm is provided. Since the welding is performed on the torso body and / or the inner lid, when welding the seal member, the welded portion between the tip of the arm portion of the seal member and the torso body and / or the inner lid has the inner lid attached. Thus, the welding operation of the seal member can be easily performed, and the sealing operation time of the radioactive substance storage container can be shortened. Also, when the seal member is removed to open the radioactive substance storage container, the welded portion between the seal member and the trunk body and / or the inner lid can be visually recognized from the opening of the trunk body to which the inner lid is attached. Therefore, the welded portion can be easily sheared, the sealing member can be easily opened, the sealing work time of the radioactive material storage container can be shortened, and the safety of workers can be improved. it can.
[0062]
According to the fourth and fifth aspects of the present invention, a seal member different from the sealing means having flexibility at least in the radial direction of the trunk main body is attached between the outer lid and the inner lid by welding. That is, since the opening of the trunk body is sealed by the sealing means and the sealing member, the reliability of the sealing of the radioactive substance storage container can be improved. Further, even when the seal member moves in the radial direction of the trunk body when the radioactive substance storage container falls or collides, the displacement of the welded portion between the seal member and the trunk body can be reduced by bending the seal member. The possibility that the welded portion is sheared can be reduced, and the reliability of the hermetic seal of the radioactive substance storage container can be maintained. Furthermore, the welding line between the seal member and the body of the body has a single welding line, so that the welding operation time of the sealing member can be shortened, the sealing operation time of the radioactive material storage container can be shortened, and the safety of workers can be improved. Can be improved.
[0063]
According to the invention described in claim 6, the seal member has an arm extending in the axial direction of the trunk main body at an end of the seal member, and the distal end of the arm is welded to the trunk main body. When welding the seal member, the welded portion of the arm portion of the seal member and the trunk body can be visually recognized from the opening of the trunk body to which the inner lid is attached, facilitating welding work of the seal member. It is possible to shorten the operation time for sealing the radioactive substance storage container. Further, when the seal member is removed to open the radioactive substance storage container, the welded portion between the seal member and the trunk body can be visually recognized from the opening of the trunk body to which the inner lid is attached. Can be easily sheared, the opening operation of the seal member can be easily performed, the sealing operation time of the radioactive substance storage container can be further reduced, and the safety of the operator can be further improved.
[0064]
Further, according to the invention described in claim 7, the arm portion comes into contact with the inner peripheral surface of the opening of the trunk main body and / or the outer peripheral surface of the inner lid while being urged in the radial direction of the trunk main body. Therefore, when the seal member is inserted into the ring-shaped space or the opening of the trunk body, the inserted position of the inserted seal member can be maintained. This eliminates the need for holding means for holding the seal member at the insertion position when welding the seal member, thereby facilitating welding of the seal member and shortening the sealing work time of the radioactive substance storage container. And the safety of the worker can be further improved.
[0065]
According to the eighth aspect of the present invention, since the seal member has the protruding portion that protrudes in the axial direction of the trunk main body, when the radioactive substance storage container falls or collides, the seal member moves in the radial direction of the trunk main body. , The protrusion of the seal member, in particular, the seal member bends, and the amount of displacement of the welded portion between the seal member and the body or between the seal member and the inner lid can be further reduced. The size can be further reduced, and the reliability of hermetic sealing of the radioactive substance storage container can be further maintained.
[0066]
According to the ninth aspect of the present invention, since a ring-shaped welding protrusion is provided on the trunk body and / or the inner lid to which the seal member is welded, the trunk body and the primary lid itself are provided with a ring-shaped welding projection. And / or the heat capacity of the welding point where the seal member is welded to the inner lid can be reduced, that is, the heat capacity can be approximated to the heat capacity of the seal member, and the welding of the seal member can be easily performed. It is possible to further reduce the time and improve the safety of the worker.
[0067]
According to the tenth aspect of the present invention, the cover is covered with a sealing member different from at least the sealing means having flexibility in the radial direction of the trunk body, and the end of the sealing member is provided on the trunk body. Since the opening is attached to the outer cylinder that covers the shield by welding, that is, the opening of the trunk body is sealed by the sealing means and the sealing member, the reliability of the sealing of the radioactive substance storage container can be improved. Further, even if the seal member moves in the radial direction of the trunk body when the radioactive substance storage container falls or collides, the displacement of the welded portion between the seal member and the outer cylinder of the trunk body is caused by bending of the seal member. The amount can be reduced, the possibility that the welded portion is sheared can be reduced, and the reliability of sealing the radioactive substance storage container can be maintained. Furthermore, since the sealing member is not already attached to the outer cylinder of the trunk body by welding after the trunk body and the lid are hermetically sealed by the sealing means, the operation is not under high radiation, so that the safety of the worker can be improved.
[Brief description of the drawings]
FIG. 1 is an axial sectional view of a radioactive substance storage container according to a first embodiment.
FIGS. 2A and 2B are diagrams showing a configuration example of a seal member according to the first embodiment, wherein FIG. 2A is an enlarged view of a portion A of FIG. 1A, FIG. FIG. 3C is an axial sectional view of the seal member before being inserted into the space.
FIG. 3 is a diagram showing another configuration example of the seal member.
FIG. 4 is a diagram showing another configuration example of the seal member.
FIG. 5 is a diagram showing a configuration example of a sealed structure of a radioactive substance storage container having a double inner lid.
FIG. 6 is a diagram showing a configuration example of a sealed structure of a radioactive substance storage container having a double inner lid structure.
FIG. 7 is an axial sectional view of a radioactive substance storage container according to a second embodiment.
8A and 8B are diagrams illustrating a configuration example of a seal member according to a second embodiment, wherein FIG. 8A is an enlarged view of a part B of FIG. 1A, FIG. 8B is a plan view of the seal member, and FIG. FIG. 3C is an axial sectional view of the seal member before being inserted into the space.
FIG. 9 is a diagram showing another configuration example of the seal member.
FIG. 10 is an axial sectional view of a radioactive substance storage container according to a third embodiment.
FIG. 11 is a view showing a structure of a lid portion of a conventional cask.
[Explanation of symbols]
1, 1 'radioactive material storage container
2 Body
3 Lid
4 Bottom plate
5 outer cylinder
6 Neutron shield
7 Inner lid
8 Outer lid
9a-c bolt
10a, b gasket
11 space
12, 12 'sealing member
12a-c protrusion
12d, e arm
13 Support lid
14 Space
15 Sealing member
16 Sealing member
20 Radioactive material storage container
30 Radioactive material storage container

Claims (10)

少なくともキャビティ内にリサイクル燃料集合体その他の放射性物質を収納するととともに、前記キャビティの周囲に中性子遮蔽体を設けた胴本体と、前記胴本体に取り付けられた蓋部と、前記胴本体と前記蓋部を密閉する密閉手段とを備える放射性物質格納容器の密閉構造において、
前記蓋部は、前記胴本体のキャビティ上方の開口部内に取り付けられる内蓋と、前記内蓋の外側に取り付けられる外蓋に備え、
前記胴本体と前記内蓋との間に少なくとも前記胴本体の径方向に可とう性を有する前記密閉手段とは異なるシール部材が溶接により取り付けられていることを特徴とする放射性物質格納容器の密閉構造。At least a recycle fuel assembly and other radioactive materials are stored in the cavity, and a trunk body provided with a neutron shield around the cavity; a lid attached to the trunk body; the trunk body and the lid And a sealing means for sealing the radioactive substance storage container comprising:
The lid portion includes an inner lid attached to an opening above the cavity of the trunk main body, and an outer lid attached to the outside of the inner lid,
Sealing of the radioactive substance storage container, characterized in that a sealing member different from the sealing means having flexibility at least in the radial direction of the trunk body is attached between the trunk body and the inner lid by welding. Construction. 前記内蓋は、その外周面に前記開口部に設けられた段差部に当接するフランジ部を有し、
前記シール部材は、前記内蓋の外周面と前記フランジ部の上面と前記胴本体の開口部の内周面とにより形成されるリング状の空間部に挿入されており、且つ前記胴本体および前記内蓋に溶接により取り付けられていることを特徴とする請求項１に記載の放射性物質格納容器の密閉構造。The inner lid has a flange portion on its outer peripheral surface that abuts on a step provided in the opening,
The seal member is inserted into a ring-shaped space formed by an outer peripheral surface of the inner lid, an upper surface of the flange portion, and an inner peripheral surface of an opening of the trunk main body, and includes the trunk main body and the The hermetically sealed structure for a radioactive substance storage container according to claim 1, wherein the hermetically sealed radioactive substance storage container is attached to the inner lid by welding. 前記シール部材は、当該シール部材の少なくとも両端部のいずれか一方に前記胴本体の軸方向に延在する腕部を有し、前記腕部の先端部を前記胴本体および／または前記内蓋に溶接することを特徴とする請求項２に記載の放射性物質格納容器の密閉構造。The seal member has an arm extending in the axial direction of the trunk main body at at least one of both ends of the seal member, and a tip end of the arm is attached to the trunk main body and / or the inner lid. The hermetically sealed structure for a radioactive substance storage container according to claim 2, wherein the container is welded. 少なくともキャビティ内にリサイクル燃料集合体その他の放射性物質を収納するととともに、当該キャビティの周囲に中性子遮蔽体を設けた胴本体と、前記胴本体に取り付けられた蓋部と、前記胴本体と前記蓋部を密閉する密閉手段とを備える放射性物質格納容器の密閉構造において、
前記蓋部は、前記胴本体のキャビティ上方の開口部内に取り付けられる内蓋と、当該内蓋の外側に取り付けられる外蓋に備え、
前記外蓋と前記内蓋との間に少なくとも当該胴本体の径方向に可とう性を有する前記密閉手段とは異なるシール部材が溶接により取り付けられていることを特徴とする放射性物質格納容器の密閉構造。At least a recycle fuel assembly and other radioactive materials are housed in the cavity, and a trunk body provided with a neutron shield around the cavity, a lid attached to the trunk main body, the trunk body and the lid And a sealing means for sealing the radioactive substance storage container comprising:
The lid portion includes an inner lid attached to an opening above the cavity of the trunk main body, and an outer lid attached to the outside of the inner lid,
Sealing of the radioactive substance storage container, wherein a sealing member different from the sealing means having flexibility at least in the radial direction of the trunk main body is attached between the outer lid and the inner lid by welding. Construction. 前記シール部材は、前記内蓋が取り付けられた前記胴本体の開口部に挿入されており、且つ前記胴本体に溶接により取り付けられていることを特徴とする請求項４に記載の放射性物質格納容器の密閉構造。The radioactive substance storage container according to claim 4, wherein the seal member is inserted into an opening of the trunk body to which the inner lid is attached, and is attached to the trunk body by welding. Closed structure. 前記シール部材は、当該シール部材の端部に胴本体の軸方向に延在する腕部を有し、前記腕部の先端部を前記胴本体に溶接することをすることを特徴とする請求項５に記載の放射性物質格納容器の密閉構造。The said seal member has the arm part extended in the axial direction of a trunk main body in the edge part of the said seal member, and welds the front-end | tip part of the said arm part to the said trunk main body, The Claims characterized by the above-mentioned. 6. A sealed structure of the radioactive substance storage container according to 5. 前記腕部は、前記胴本体の開口部の内周面および／または前記内蓋の外周面に前記胴本体の径方向に付勢された状態で接触していることを特徴とする請求項３または６に記載の放射性物質格納容器の密閉構造。The said arm part has contacted the inner peripheral surface of the opening part of the said trunk | drum main body, and / or the outer peripheral surface of the said inner lid in the state biased in the radial direction of the said trunk | drum main body, The 3rd aspect. Or a sealed structure of a radioactive substance storage container according to 6. 前記シール部材は、前記胴本体の軸方向に突出する突出部を有することを特徴とする請求項１〜７のいずれか一つに記載の放射性物質格納容器の密閉構造。The hermetically sealed structure for a radioactive substance storage container according to any one of claims 1 to 7, wherein the seal member has a protruding portion that protrudes in an axial direction of the trunk main body. 前記シール部材が溶接される前記胴本体および／または前記内蓋にリング状の溶接突起部を設けたことを特徴とする請求項１〜８のいずれか一つに記載の放射性物質格納容器の密閉構造。The hermetically sealed radioactive substance storage container according to any one of claims 1 to 8, wherein a ring-shaped welding protrusion is provided on the trunk body and / or the inner lid to which the seal member is welded. Construction. キャビティ内にリサイクル燃料集合体その他の放射性物質を収納するととともに、当該キャビティの周囲に中性子遮蔽体を設けた胴本体と、当該胴本体に取り付けられた蓋部と、前記胴本体と前記蓋部を密閉する密閉手段とを備える放射性物質格納容器の密閉構造において、
少なくとも前記胴本体の径方向に可とう性を有する前記密閉手段とは異なるシール部材で前記蓋部を覆い、
前記シール部材の端部を前記胴本体に設けた中性子遮蔽体を覆う外筒に溶接より取り付けることを特徴とする放射性物質格納容器の密閉構造。Along with housing the recycled fuel assembly and other radioactive materials in the cavity, a trunk body provided with a neutron shield around the cavity, a lid attached to the trunk main body, the trunk body and the lid In the hermetic structure of the radioactive substance storage container having a hermetic sealing means,
Covering the lid with a sealing member different from the sealing means having flexibility at least in the radial direction of the trunk body,
The hermetically sealed structure of a radioactive substance storage container, wherein an end of the seal member is attached to an outer cylinder covering a neutron shield provided on the trunk body by welding.
JP2002293099A 2002-10-04 2002-10-04 Radioactive containment enclosure Expired - Lifetime JP3848913B2 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6990166B2 (en) * 2001-06-29 2006-01-24 Mitsubishi Heavy Industries, Ltd. Closed vessel for radioactive substance, seal-welding method for closed vessel, and exhaust system used for seal-welding method
JP2008089487A (en) * 2006-10-04 2008-04-17 Toshiba Corp Radioactive substance containing cask and repair method therefor
CN109378100A (en) * 2018-09-20 2019-02-22 原子高科股份有限公司 A kind of sealing bucket of double-canopy structure

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6990166B2 (en) * 2001-06-29 2006-01-24 Mitsubishi Heavy Industries, Ltd. Closed vessel for radioactive substance, seal-welding method for closed vessel, and exhaust system used for seal-welding method
JP2008089487A (en) * 2006-10-04 2008-04-17 Toshiba Corp Radioactive substance containing cask and repair method therefor
CN109378100A (en) * 2018-09-20 2019-02-22 原子高科股份有限公司 A kind of sealing bucket of double-canopy structure

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