Neutronic Analysis on Potential Accident Tolerant Fuel-Cladding Combination U$_3$Si$_2$-FeCrAl

TL;DR

This study evaluates the neutronic performance of a novel U$_3$Si$_2$-FeCrAl fuel-cladding system, demonstrating its potential as an accident tolerant fuel with improved reactivity stability and acceptable power distribution characteristics.

Contribution

It introduces and analyzes a new U$_3$Si$_2$-FeCrAl fuel-cladding combination, highlighting its neutronic advantages over current systems for accident tolerance.

Findings

Less reactivity variation during service lifetime

Slightly larger power distribution deviation

Reduced importance of control rods worth

Abstract

Neutronic performance is investigated for a potential accident tolerant fuel (ATF),which consists of U$_3$Si$_2$ fuel and FeCrAl cladding. In comparison with current UO$_2$-Zr system, FeCrAl has a better oxidation resistance but a larger thermal neutron absorption cross section. U$_3$Si$_2$ has a higher thermal conductivity and a higher uranium density, which can compensate the reactivity suppressed by FeCrAl. Based on neutronic investigations, a possible U$_3$Si$_2$-FeCrAl fuel-cladding systemis taken into consideration. Fundamental properties of the suggested fuel-cladding combination are investigated in a fuel assembly.These properties include moderator and fuel temperature coefficients, control rods worth, radial power distribution (in a fuel rod), and different void reactivity coefficients. The present work proves that the new combination has less reactivity variation during its service lifetime. Although, compared with the current system, it has a little larger deviation on power distribution and a little less negative temperature coefficient and void reactivity coefficient and its control rods worth is less important, variations of these parameters are less important during the service lifetime of fuel. Hence, U$_3$Si$_2$-FeCrAl system is a potential ATF candidate from a neutronic view.