Investigation of resonance self-shielding effect in PWR cladding material for Zirconium isotopes

Abstract

The Zirconium isotopes have been widely used in many PWR fuel cladding materials. Ignoring the resonance self-shielding effect for Zirconium isotopes, it may introduce 100–300 pcm errors in PWR reactivity predictions. The reference dilution cross section, equivalence theory, and subgroup method can be used in treating resonance self-shielding effect for Zirconium isotopes. Hence, it is important to determine the application and accuracy of these methods. In this paper, the three methods are tested with the DRAGON5.0.1 code based on the different PWR cases. The result of reactivity and absorption cross section is then compared with the Monte-Carlo code cosRMC. It indicates that the resonance self-shielding effect for Zirconium isotopes is related to the cladding region’s thickness, cladding material’s nuclide density, and water/uranium ratio. The equivalence theory and subgroup method are more flexible in treating the resonance self-shielding for Zirconium isotopes. The reference dilution cross section is limited to the typical PWR cases with a specific geometry, nuclide density, and water/uranium ratio. It is demonstrated that the equivalence theory and subgroup method can accurately treat the resonance self-shielding effect for Zirconium isotopes.