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Li, F.; 成川 隆文; 宇田川 豊
Journal of Nuclear Science and Technology, 12 Pages, 2023/00
被引用回数：0 パーセンタイル：0.01(Nuclear Science & Technology)The seismic resistance of fuel cladding during the long-term core cooling after loss-of-coolant accidents (LOCAs) was investigated by performing cyclic four-point bending tests (4PBTs) of up to 1000 cycles with fresh fuel cladding samples that experienced integral thermal shock test, simulating LOCA conditions, including ballooning, rupture, oxidation, and quench. 4PBTs were performed on the samples that survived the quenching process. The results showed that up to 1000 cycles and 5.8 Nm of cyclic loading moment, there was no apparent effect on the bending fracture limit of the fuel cladding under the 4PBT. The scatter of the bending fracture limit for a given equivalent cladding reacted (ECR) evaluated by the Baker-Just oxidation rate equation (BJ-ECR) is attributed to two primary factors: first, the difference between the prescribed and the actual oxidation behavior, confirmed by comparing the BJ-ECR and the ECR evaluated based on metallographic observation (M-ECR), and second, the variated shape of the rupture-opening area after the integral thermal shock test. The strength of the alpha phase-dominant zone near the rupture opening seems to contribute to the bending fracture limit.
湯村 尚典; 天谷 政樹
Annals of Nuclear Energy, 120, p.798 - 804, 2018/10
被引用回数：6 パーセンタイル：51.86(Nuclear Science & Technology)To investigate the relationship between the fracture resistance of a cladding tube and the amount of deformation of the cladding tube due to ballooning and rupture during a loss-of-coolant accident (LOCA), four-point-bending tests were performed using non-irradiated Zircaloy-4 cladding tubes which experienced a LOCA-simulated sequence (ballooning, rupture, high temperature oxidation and quench). According to the obtained results, it was found that the maximum bending stress of the cladding tube after the LOCA-simulated sequence, which was defined as the fracture resistance, correlated to the average thickness of prior-
layer in the cladding tube. Based on the average thickness of prior- layer, the fracture resistance of the cladding tube with ballooning and rupture was expressed as functions of isothermal oxidation time and temperature and the maximum circumferential strain on the cladding tube.
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。
