Abstract The number of Displacement per Atom (DPA) in the fuel cladding is a key quantity for determining the operation lifetime of fuel assemblies in Sodium-cooled Fast Reactor (SFR). Since the cladding is directly irradiated by Fission Products (FPs), the present work evaluates the FPs-induced atomic displacements in the Fe-14Cr cladding. Three degrees of freedom (the yields of FPs, energy distribution, and angular distribution of each FP) are reduced using the assumptions proposed in this paper. Two additional approximations are proposed to obtain the reasonable upper and lower limits of DPA in the cladding so that the computation burden is largely reduced. Numerical results show that the proposed approximations can give a reasonable estimate of the FPs-induced DPA in the fuel cladding. The FPs-induced damage is limited in the range of few microns but can be 5 times more important than the neutron-induced one in the cladding of ASTRID inner core. Along with the depth in the cladding, the FPs-induced damage rate becomes less important than the neutron-induced one at penetration deeper than 5 μ m and smaller than 1/10 of neutron-induced DPA at penetration larger than 7 μ m . A subsequent question of whether the FPs-induced damage should be taken into account in the cladding needs to be discussed for SFRs.

中文翻译：

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裂变产物对快堆燃料包壳位移损伤的贡献

摘要 燃料包壳中的每原子位移数（DPA）是决定钠冷快堆（SFR）燃料组件使用寿命的关键量。由于包壳直接受到裂变产物 (FPs) 的辐射，本工作评估了 Fe-14Cr 包壳中 FPs 引起的原子位移。使用本文提出的假设减少了三个自由度（FP 的产量、能量分布和每个 FP 的角度分布）。提出了两个额外的近似值来获得包层中 DPA 的合理上限和下限，从而大大减少计算负担。数值结果表明，所提出的近似值可以对燃料包壳中由 FPs 引起的 DPA 给出合理的估计。FPs 引起的损伤被限制在几微米的范围内，但在 ASTRID 内核的包层中可能比中子引起的损伤重要 5 倍。随着包层深度的增加，FPs 诱导的损伤率在穿透深度超过 5 μm 时不如中子诱导损伤率重要，并且在穿透大于 7 μm 时小于中子诱导 DPA 的 1/10。对于 SFR，需要讨论在包层中是否应考虑 FP 引起的损坏的后续问题。在穿透深度超过 5 μm 时，FPs 诱导的损伤率变得不如中子诱导的损伤率重要，并且在穿透大于 7 μm 时小于中子诱导的 DPA 的 1/10。对于 SFR，需要讨论在包层中是否应考虑 FP 引起的损坏的后续问题。在穿透深度超过 5 μm 时，FPs 诱导的损伤率变得不如中子诱导的损伤率重要，并且在穿透大于 7 μm 时小于中子诱导的 DPA 的 1/10。对于 SFR，需要讨论在包层中是否应考虑 FP 引起的损坏的后续问题。