Study on Resonance Self-shielding Calculation for Zirconium Isotope in PWR Fuel Cladding

Zirconium alloys are widely used in PWR fuel assembly manufacture because of their corrosion resistance, mechanical strength, and neutronics characteristics. However, 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 k_inf results. Moreover, the applicability of the method in the resonance calculation of dispersion fuel zirconium base was preliminarily discussed as well.