压水堆燃料包壳锆同位素共振计算研究

摘要

锆合金因具有耐腐蚀、耐辐照、低蠕变,以及较好的中子学性能等特点,被广泛用于制造压水堆燃料包壳管、定位格架等燃料组件构件.从中子物理学角度,锆同位素在中能区存在较为明显的共振现象.工业应用广泛的传统等价理论共振方法只考虑燃料区的共振效应,对于包壳材料中锆同位素的共振现象,通常予以忽略,或简单以典型参考背景截面(通常为3×10-22cm2)下产生的微观截面来考虑.这些传统处理方式可能会导致多达200~300pcm的反应性偏差.因此,基于对影响压水堆燃料包壳锆同位素有效共振截面的各种主要因素的分析,本文确定了一种预制截面表的锆同位素共振计算方法.数值结果表明,这种共振处理方法可提供较为准确的锆同位素多群微观截面,并能有效改善组件无限增殖因数的计算精度.此外,也对这种方法在弥散型燃料锆基体共振计算中的适用性进行了探讨.%Zirconium alloys are widely used in PWR fuel assembly manufacture because of their corrosion resistance,mechanical strength,and neutronics characteristics.How-ever,zirconium isotopes have resonances in the medium energy range,which are often ignored or treated by a typical background cross section in conventional equivalence theory calculations.These may cause reactivity deviation even up to 200-300 pcm.In this paper,the factors which impact the effective cross section for zirconium isotope resonance in PWR fuel cladding were analyzed,and a method based on the cross section pre-tabulation strategy was studied.The numerical results demonstrate that the proposed method provides accurate zirconium isotope cross sections and improves kinf results.Moreover,the applicability of the method in the resonance calculation of disper-sion fuel zirconium base was preliminarily discussed as well.