Thermal-hydraulic analysis in local fuel region of helium gas-cooled fast breeder reactor with coated-particle-type fuel

not registered; Ohshima, Hiroyuki

Feasibility Study is being carried out at JNC to generate new concepts for commercialized fast breeder reactors. In this study, a helium gas-cooled reactor with coated-particle-type fuel is proposed, as one of the candidates for fast breeder reactors. Each fuel assembly has a compartment of an annular duct shape and the annular space of the compartment is filled with coated-particle-type fuels. The assessment of heat removal capability of coolant flowing in the coated-particle-fuel region and the endurance of fuel particle is one of the important issues in the reactor safety. In the present study, a thermal-hydraulic analysis was carried out in order to clarify flow and temperature fields in a local coated-particle-fuel region as well as in-particle temperature distributions. The FLUENT code was applied to this numerical analysis and the simulations were performed using five face-center cubic unit cells, which were combined with one another in the flow direction. Through the analysis, it was confirmed that the extreme temperature peak in coolant did not appear in the local Coated-particle-fuel region and the temperature in a coated fuel particle rises along the flow direction almost linearly except fuel core region. With respect to the surface temperature of a coated fuel particle, the maximum and the minimum temperatures appear at the downstream and the upstream contact points with neighboring particles, respectively. Further, the calculation results by FLUENT were compared with Ergun's correlation in order to verify the applicability of it to the pressure drop estimation in the coated-particle-fuel region. The friction coefficient estimated by FLUENT agreed with that by Ergun's correlation with errors from -11% to 20% for 2 Re 154.