Preliminary Safety Evaluation of LWR Deep Burn Core

For effective management of high-level waste from light water reactors (LWRs), a modified open fuel cycle concept that deeply burns recycled transuranics (TRUs) from LWR spent fuel in existing LWR fleet is proposed (hereinafter called LWR-DB (deep burn)). LWR-DB introduces a fully ceramic microencapsulated (FCM) fuel that can achieve super high burn-up, thus, to burns TRUs up to ∼60% by a single irradiation. LWRDB fuel assemblies contain both typical UO2 pins and FCM fuel pins in which TRISO TRU particles are distributed in SiC matrix pellets. Assets of FCM fuel are its high thermal conductivity leading to low fuel temperature, thus initial stored energy, and the highly refractory and fission product (FP) retentive features of FCM pellet composed of TRISO particles and SiC matrix. In this work, the safety of LWR-DB core is preliminarily evaluated for reference plant, YGN 3 and 4 using MARS3.1. Major accidents analyzed are the large break loss-of-coolant accident (LBLOCA) and loss-offlow- accident (LOFA)