Isotopic concentrations in Un/U 3 Si 2 accident tolerant fuel pin with zirconium and iron-based claddings

Novel fuel and/or cladding design to increase the safety factors regarding nuclear accidents are appreciated after the Fukushima Daiichi disaster. Neutronic analysis for evaluating the safety of accident-tolerant fuel is inevitable. In this paper, a standard OECD UAM TMI-1 PWR standard pin cell and a proposed accident-tolerant fuel (UN/U3Si2), along with conventional zirconium and advanced powder metallurgical ferritic, APMT, claddings, are evaluated from mainly neutronic parameter point of view, with an emphasis on the calculation of the radial isotopic distribution. An analytical formula is also suggested for predicting the radial isotopic distribution of UN/U3Si2 fuel pin for two different claddings. Moreover, the rim effect is compared for both fuels, along with considering different self-shielding methods and various numbers of neutron energy groups. In the current work, the calculations are performed with DRAGON, WIMS-D5, and Monte Carlo codes. The obtained results demonstrate that selecting a proper self-shielding method and an appropriate library group are influential to attain the correct rim effect. The results indicate that proper selection of self-shielding methods and library groups is crucial for accurate rim effect prediction. Using the GSM model, the best k-infinity predictions were obtained with GSM-NOLJ models, showing differences of up to 541 pcm for UO₂ and 310 pcm for UN/U₃Si₂ compared with MCNP, while GSM-LJ-0 significantly overestimated k-infinity. Additionally, UN/U₃Si₂ exhibits a slightly higher and sharper 239Pu distribution than UO₂.