Abstract
The transient characteristics of single- phase natural circulation flow caused by pump tripping are investigated experimentally and analytically for five different cooling configurations in loop-type PWRs for marine applications. The loop consists of a heater box, a cooler, and connecting bent pipes with inverse U shapes. The cooler Jacket is designed to provide five different cooling configurations; three inverse U-shaped and two straight tube types. The experiments are carried out using water as the working fluid at atmospheric pressure by holding the heater input constant ( Q = 0.25kW to 4.0kW) . Under a certain condition, an unstable flow, which developes a reverse flow with a periodic oscillation, occurs. The flow stability maps are obtained for the heat input Q vs the heater height ELhfor five cooling configurations. Furthermore, a one-dimensional nonlinear analysis is carried out. The analytical results agree well with the experimental results.
