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成川 隆文
no journal, ,
JAEA has conducted studies on fuel behaviors under loss-of-coolant-accident (LOCA) conditions with both unirradiated and high-burnup advanced fuel cladding tubes. As a result, various kinds of information have been obtained on behaviors of these cladding tubes under LOCA conditions: oxidation, ballooning and rupture, thermal shock resistance (fracture/non-fracture conditions), post-LOCA mechanical strength, etc. In addition, new LOCA tests are planned at JAEA for the purpose of investigating effects of phenomena of fuel fragmentation, relocation and dispersal (FFRD) on fuel behaviors and coolability of reactor core during LOCA. It is expected that these results including those obtained by the future study provide necessary information for future regulation on high-burnup fuels with advanced cladding alloys.
湯村 尚典; 天谷 政樹
no journal, ,
LOCA時の温度履歴を模擬した条件下で膨れ破裂及び酸化させた未照射被覆管を用いて4点曲げ試験を実施した。その結果、膨れ量の増加に伴い曲げ強度が低下する傾向が見られた。これは被覆管の機械強度を左右するprior-
相厚さが膨れ量の増加に伴い減少する影響と考えられる。また膨れ量約30%以下の領域では破裂開口部以外に荷重点もしくは支持点での破損も見られた。酸化後の被覆管の軸方向水素濃度分布を調べた結果、荷重点または支持点での二次水素化による影響と考えられるピークが観察されていることから、被覆管の曲げ強度は、膨れ量が小さくなるとprior-相の厚さに加え二次水素化による脆化の影響も受けるようになると考えられる。
成川 隆文
no journal, ,
JAEA has conducted studies on fuel behaviors under loss-of-coolant-accident (LOCA) conditions with both unirradiated and high-burnup advanced fuel cladding tube materials. As a result, various kinds of information have been obtained on behaviors of these cladding tube materials under LOCA conditions: oxidation, ballooning, rupture, thermal shock resistance (fracture/non-fracture conditions), post-LOCA mechanical strength, etc. In addition, new LOCA tests are planned at JAEA for the purpose of investigating effects of phenomena of fuel fragmentation, relocation and dispersal (FFRD) on fuel behaviors and coolability of reactor core during a LOCA. It is expected that these results including those obtained by the future study provide necessary information for future regulation on high-burnup fuels with advanced cladding alloys.
成川 隆文
no journal, ,
JAEA has carried out studies on fuel behaviors under loss-of-coolant-accident (LOCA) conditions with both unirradiated and high-burnup advanced fuel cladding tube materials. As a result, various kinds of information have been obtained: oxidation, ballooning, rupture, thermal shock resistance (fracture/non-fracture conditions), post-LOCA mechanical strength, etc. In addition, new LOCA tests are planned at JAEA to investigate the effects of the phenomena of fuel fragmentation, relocation and dispersal (FFRD) on the fuel behaviors and the coolability of the reactor core during a LOCA. These results, including those obtained from the future study, are expected to provide the necessary information for future regulation on high-burnup fuels with advanced cladding alloys.
成川 隆文
no journal, ,
JAEA has performed a wide range of loss-of-coolant-accident (LOCA) studies in response to fuel-burnup extension, new experimental results, and the accident at NPPs. Currently, new LOCA tests are ongoing in JAEA to evaluate fuel behavior under LOCA conditions including the phenomena of fuel fragmentation, relocation, and dispersal (FFRD) and the mechanical strength of fuel cladding tubes during the post-LOCA long-term core cooling period. These test results, including those obtained from the future study, are expected to provide the necessary information for the future regulation on high-burnup fuels.
成川 隆文; 宇田川 豊; 天谷 政樹
no journal, ,
冷却材喪失事故(LOCA)後に長期にわたって炉心の冷却可能形状を維持できるか否かを評価するために必要な、燃料被覆管のLOCA後耐破断性に及ぼすLOCA時二次水素化の影響、並びに燃焼の進展及び被覆管材質変更の影響を評価することを目的に、LOCA模擬試験後の非照射燃料被覆管及び高燃焼度改良型燃料被覆管に対し4点曲げ試験を実施し、作用する曲げに対する耐破断性を評価した。その結果、燃料被覆管の二次水素化した領域は酸化のみの領域(破裂開口部)に比べ最大曲げ応力が半分程度に低下し、LOCA時の膨れ量及び酸化量次第で燃料被覆管は二次水素化部で破断する可能性があること、並びにLOCA後耐破断性は通常運転中の水素吸収量の増大に伴い若干低下するものの約85GWd/tまでの燃焼度進展や被覆管材質の変更により著しく低下しないことを明らかにした。