Impact of improved neutronic methodology on the cladding response during a PWR reactivity initiated accident

When applied to reactivity initiated accidents (RIAs) analysis, codes such as DeCART can provide a detailed radial, azimuth, and axial power distribution within a fuel rod. The work reported here is aimed at quantifying the sensitivity of the cladding thermo-mechanical response, calculated by the fuel performance code FALCON to the more accurate and detailed neutronic solution provided by DeCART for full PWR core RIA analysis. As a basis of comparison, the neutronics analysis is also performed with the U.S. NRC PARCS code, which is representative of the methodology used by the industry. on the DeCART solutions, several fuel rods are chosen for analysis with FALCON according to several relevant criteria. For each of the selected fuel rods, a FALCON study is performed using the boundary conditions provided by the neutronic solvers to predict the cladding response in terms of Strain Energy Density (SED) to the power pulse during the transient. The results of the analysis led to the following conclusions:• rgest impact on the cladding response can be attributed to the differences in the kinetic parameters in PARCS and DeCART. deling of fuel pin exposure in the current industry standard “two step” methodology can result in some significant discrepancies in terms of SED during RIA analysis. fect of azimuthal power variation within a given fuel rod has a 10% impact on the SED and should be taken into consideration during RIA analysis, especially for high exposure fuel.