Analysis of TRISO failure fraction in PeLUIt reactor with increasing power

This study investigates the impact of increasing power in the PeLUIt reactor on the failure fraction of TRISO-coated fuel particles during both normal operation and Depressurized Loss of Forced Cooling (DLOFC) accident scenarios. In this study, the core geometry is preserved despite of the power changes while the coolant velocity is adjusted to maintain the intlet and outlet temperatures. The TRIAC-BATAN code was used to evalute the failure fraction of TRISO-coated fuel particles at various reactor power ranging from 10 MWt to 50 MWt. Neutronic calculations for PeLUIt were conducted using the PEBBED code, while irradiation and DLOFC accident temperatures were analyzed through a combination of PEBBED 1-D and THERMIX-KONVEX, coupled with PEBBED. The results show that at lower power (10 MWt to 30 MWt), the failure fraction of TRISO particles remains low, with minimal increases as power rise. However, above 30 MWt, an exponential increase in failure fraction is observed, particularly beyond 40 MWt. At 50 MWt, when fuel temperatures exceed the safety threshold of 1600 °C during DLOFC, a significant rise in TRISO particle failure occurs, accompanied by degradation of the SiC layer.