Neutronic characteristics analysis of accident tolerant fuel and claddings for fuel assembly of light water reactor

UO2 fuel with zirconium-based cladding material (UO2−Zr) is being used in the LWR reactor since it has optimal performance under normal conditions. At temperatures above 800°C, zirconium oxidation by water can occur which is an exothermic reaction and could lead to hydrogen production. For this reason, accident tolerant fuel (ATF) is needed as a solution to increase reactor safety but also maintain or further increase efficiency and fuel reliability. U3Si2 fuel has a higher uranium density and thermal conductivity than UO2 fuel, which could be used to compensate for negative reactivity caused by cladding material. The purpose of this study was to determine the neutronic parameters of U3Si2 fuel material in combination with various types of cladding material, e.g Zr-based, SS310, SS304, FeCrAl, APMT, HT9, and SiC, on the AP1000 standard 17×17 fuel assembly. Calculated neutronic parameters are infinite multiplication factor (k-inf), Doppler temperature coefficient (DTC), moderator temperature coefficient (MTC), and neutron spectrum. The calculation results will be compared with a reference UO2−Zr fuel assembly. Calculations were carried out under hot full power (HFP) conditions without soluble boron and with 1184 ppm soluble boron using SRAC2006 code and ENDF/B-VII.0 cross-section library. The k-infinity difference compared to the reference (UO2−ZIRLO) of U3Si2 fuel with SiC cladding without soluble boron is 464.80 pcm, and 1226.44 pcm with 1184 ppm soluble boron. The difference due to the presence of soluble boron caused UO2 fuel to have a larger thermal neutron spectrum than U3Si2, hence making soluble boron more effective in oxides fuel rather than silicide fuel. U3Si2 fuel material with cladding material FeCrAl and APMT has a difference lower than 4500 pcm, while with SS310, SS304, and HT9 cladding has a difference of 5000-7500 pcm compared to the reference. The fuel temperature coefficient (DTC) and moderator reactivity coefficient (MTC) is negative which same as the reference and shows an inherent safety feature. Based on the results of this calculation, U3Si2 fuel with SiC, FeCrAl, and AMPT cladding has the potential as an ATF candidate from the neutronic aspect.