The potential impact of Fully Ceramic Microencapsulated (FCM) fuel on thermal hydraulic performance of SMART reactor

One of emerging advanced fuel materials for the next generations of the nuclear reactors is Fully Ceramic Microencapsulated (FCM) fuel. FCM fuel structure is comprised of TRISO particles dispersed randomly in a SiC matrix. In the present study, the thermal hydraulic performance of a SMART reactor is investigated and the results are compared with the case that conventional UO2 fuel is loaded into the core. At the beginning of the cycle, the reactor is simulated in normal operational and transient conditions. MCNPX 2.6 stochastic code is utilised to calculate neutronic parameters. COMSOL and RELAP5 codes are used for thermal hydraulic analysis. The reactor dynamics is simulated based on six-group point kinetics and lumped parameters thermal hydraulic model. A ramp input reactivity is inserted into the core and the behaviour of the two fuel types are examined. As FCM fuel is heterogeneous structurally, detailed analysis is also performed. Homogenization of FCM fuel material might be a serious error source in related calculations. This is investigated numerically and the results are discussed in details.