ABSTRACT To evaluate the fracture resistance of high-burnup advanced fuel cladding tubes during the long-term core cooling period following loss-of-coolant accidents (LOCAs), laboratory-scale four-point-bend tests were performed using the following advanced fuel cladding tubes with burnups of 73–84 GWd/t: low-tin ZIRLOTM, M5®, and Zircaloy-2 (LK3). Three four-point-bend tests were performed on the high-burnup advanced fuel cladding tube specimens subjected to the integral thermal shock tests which simulated LOCA conditions (ballooning and rupture, oxidation in high-temperature steam, and quench). During the four-point-bend tests, all the specimens that were oxidized at 1474 K to 9.9%–21.5% equivalent cladding reacted exhibited brittle fractures. The maximum bending moments were comparable to those of the conventional Zircaloy cladding tube specimens. Furthermore, the effects of oxidation and hydriding on the maximum bending moment were comparable between the high-burnup advanced fuel cladding tube specimens and the unirradiated Zircaloy-4 cladding tube specimens. Therefore, it can be concluded that the post-LOCA fracture resistance of fuel cladding tubes is not significantly reduced by extending the burnup to 84 GWd/t and using the advanced fuel cladding tubes, though it may slightly decrease with increasing initial hydrogen concentration in a relatively lower ECR range (< 15%), as observed for the unirradiated Zircaloy-4 cladding tubes.

中文翻译：

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暴露于模拟 LOCA 条件后的高燃耗先进燃料包壳管的四点弯曲试验

摘要 为了评估高燃耗先进燃料包壳管在冷却剂丢失事故 (LOCA) 后长期堆芯冷却期间的抗断裂性，使用以下先进燃料包壳进行了实验室规模的四点弯曲试验燃耗为 73–84 GWd/t 的管：低锡 ZIRLOTM、M5® 和 Zircaloy-2 (LK3)。对高燃耗先进燃料包壳管试样进行了三个四点弯曲试验，该试样经受了模拟 LOCA 条件（膨胀和破裂、高温蒸汽中的氧化和淬火）的整体热冲击试验。在四点弯曲试验期间，所有在 1474 K 下氧化至 9.9%–21.5% 等效包层反应的试样均表现出脆性断裂。最大弯矩与传统的锆合金包覆管试样的弯矩相当。此外，氧化和氢化对最大弯矩的影响在高燃耗先进燃料包壳管样品和未经辐照的 Zircaloy-4 包壳管样品之间具有可比性。因此，可以得出结论，通过将燃耗延长至 84 GWd/t 并使用先进的燃料包壳管，燃料包壳管的后 LOCA 断裂抗力没有显着降低，尽管它可能会随着初始氢浓度的增加而略有下降。相对较低的 ECR 范围 (< 15%)，如未辐照的 Zircaloy-4 包覆管所观察到的那样。氧化和氢化对最大弯矩的影响在高燃耗先进燃料包壳管样品和未经辐照的 Zircaloy-4 包壳管样品之间具有可比性。因此，可以得出结论，通过将燃耗延长至 84 GWd/t 并使用先进的燃料包壳管，燃料包壳管的后 LOCA 断裂抗力没有显着降低，尽管它可能会随着初始氢浓度的增加而略有下降。相对较低的 ECR 范围 (< 15%)，如未辐照的 Zircaloy-4 包覆管所观察到的那样。氧化和氢化对最大弯矩的影响在高燃耗先进燃料包壳管样品和未经辐照的 Zircaloy-4 包壳管样品之间具有可比性。因此，可以得出结论，通过将燃耗延长至 84 GWd/t 并使用先进的燃料包壳管，燃料包壳管的后 LOCA 断裂抗力没有显着降低，尽管它可能会随着初始氢浓度的增加而略有下降。相对较低的 ECR 范围 (< 15%)，如未辐照的 Zircaloy-4 包覆管所观察到的那样。