Three-Dimensional Analysis of Flow and Heat Transfer in A Wire-Wrapped Fuel Assembly

초록

In this work, three-dimensional analysis of flow and heat transfer has been performed for a wire-spacer fuel assembly of liquid metal reactor using RANS (Reynolds-averaged Navier-Stokes equations) analysis. SST model is used as a turbulence closure. The whole fuel assembly has been analyzed for one period of the wire-spacer using periodic boundary conditions at inlet and outlet of the calculation domain. Three different assemblies, two 7-pin wire-spacer fuel assemblies and one bare rod bundle, apart from the pressure drop calculation for a 19-pin case have been analyzed. Individual as well as a comparative analysis of the flow field and heat transfer have been discussed. The flow field in the subchannels of a bare rod bundle and a wire-spacer fuel assembly is found to be different. However, similar subchannel velocity distribution is observed in both the cases when the wire-wraps move out of the subchannel. The wire-spacer decreases the temperature gradients in the subchannels of fuel assembly. Directional temperature gradient is found to exist in the subchannels of a wire-spacer fuel assembly. Local Nusselt number in the subchannels of wire-spacer fuel assemblies is found to vary according to the wire-wrap position while in case of bare rod bundle, it’s found to be constant.