抄録
Enhanced thermal conductivity materials such as composite of UO2 with addition of compounds like BeO and SiC have been developed for better thermal performances. In this study a thermalhydraulic code RELAP-5/MOD3.3 is used to study temperature patterns, pressure, core water level and void fraction in a PWR core with UO2-10%vol BeO composite fuel. A cold leg break loss of coolant accident case was studied. The initial steady state conditions indicated that the fuel temperature is significantly reduced in axial and radial directions for UO2-BeO fuel compared to UO2 fuel. RELAP5 transient operation cases were conducted for both UO2 and UO2-10vol%BeO fuel materials under two conditions, one is with scram and 14.0 sec delay water injection, and the other one is without scram or water injection. For UO2-10vol%BeO fuel material, the transient temperature profiles were much lower than the UO2 fuel while the core pressure and core water level were almost the same as UO2 fuel case. From these transient studies, it was observed that reduction of nearly 20% in fuel temperatures was observed with composite fuel. Void fraction in the reactor vessel was lower by a small amount for the composite fuel while pressure and water level in the reactor vessel were not found to vary.
