Hydraulic study on recirculation loops using computational fluid dynamics (CFD). Design optimization and turbulence reduction

A full scope study of the recirculation system flow of a BWR6 nuclear plant is essential, to completing the characterisation and understanding the dynamics of the flow and specially the bistable flow in the recirculation loop. The finite element model serves to study the sensitivity of the design and to reduce turbulence at the connection between the recirculation pump impulsion piping and the manifold. It is found that the problem lies in the poor hydraulic design of the manifold. As a result of this analysis, in order to reduce turbulence and balance flows in the jet pumps the manifold diameter needs to be increased. The simulation shows the unbalanced flow to the jet pump pipes. This fact can be checked in any nuclear power plant BWR