A fuel performance analysis for a 450 MWth deep burn-high temperature reactor

A performance analysis for a 450 MWth deep burn-high temperature reactor (DB-HTR) fuel was performed using COPA, a fuel performance analysis code of Korea Atomic Energy Research Institute (KAERI). The code computes gas pressure buildup in the void volume of a tri-isotropic coated fuel particle (TRISO), temperature distribution in a DB-HTR fuel, thermo-mechanical stress in a coated fuel particle (CFP), failure fractions of a batch of CFPs, and fission product (FP) releases into the coolant. The 350 μm DB-HTR kernel is composed of 30% UO2 + 70% (5% NpO2 + 95% PuO1.8) mixed with 0.6 moles of silicon carbide (SiC) per mole of heavy metal. The DB-HTR is operated at the constant temperature and power of 858 °C and 39.02 mW per CFP for 1395 effective full power days (EFPD) and is subjected to a core heat-up event for 250 h during which the maximum coolant temperature reaches 1548.70 °C. Within the normal operating temperature, the fuel showed good thermal and mechanical integrity. At elevated temperatures of the accident event, the failure fraction of CFPs resulted from the mechanical failure (MF) and the thermal decomposition (TD) of the SiC barrier is 3.30 × 10−3.

► We have checked, through a fuel performance analysis, if a 450 MWth high temperature reactor was safe for the deep burn of a TRU fuel. ► During a core heat-up event, the fuel temperature was below 1600 °C and the maximum gas pressure in the void of coated fuel particle was about 90 MPa. ► At elevated temperatures of the accident event, the failure fraction of coated fuel particles resulted from the mechanical failure and the thermal decomposition of the SiC barrier was 3.30 × 10−3.