[en] A review of irradiation-induced swelling and gas release experience is presented here for the three principal fuels UO₂, UC, and UN. The primary advantage of UC and UN over UO₂ is higher thermal conductivity and attendant lower fuel temperature at equivalent pellet diameter and power density, while UO₂ offers the distinct benefit of well-known irradiation performance. Irradiation test results indicate that at equivalent burnup, temperature, and porosity conditions, UC experiences higher swelling than UO₂ or UN. Fission gas swelling becomes important at fuel temperatures above 1320 K for UC, and at somewhat higher temperatures for UO₂ and UN. Evidence exists that at equivalent fuel temperatures and burnups, high density UO₂ and UN experience comparable swelling behavior; however, differences in thermal conductivity influence overall irradiation performance. The low conductivity of UO₂ results in higher thermal gradients which contribute to fuel microcracking and gas release. As a result UO₂ exhibits higher fractional gas release than UN, at least or burnups up to about 3%