High uranium loading TRISO particle for microreactor applications

Abstract

Tristructural isotropic (TRISO) fuel is currently being considered for novel high-temperature reactor (HTR) designs that deviate significantly from the prismatic or pebble bed modular high-temperature gas-cooled reactors (MHTGRs) that have been the focus of development efforts for the last four decades. These new designs include microreactors with compact cores that can benefit from increasing the core fissile density beyond that conventionally required in an MHTGR using TRISO fuel to enable longer fuel in-core residence time or higher power density. One means of increasing the fissile density in an HTR core is to adjust the coated particle design to increase the ratio of kernel volume to total particle volume. This would increase the volume of fissile phase in a fuel compact with no increase in particle packing fraction beyond that used in fuel compacts tested by the AGR program. Results show that the end-of-life failure probabilities of these high uranium loading particles and those of the validated reference particles are similarly low (∼2 × 10-5) for burnups of at least 9 % FIMA.