Computation of natural convection test at Phenix reactor using the NETFLOW++ code

The present paper describes modeling and analyses of a natural convection test of the pool-type fast breeder reactor (FBR) Phenix. The natural convection test was carried out as one of the end-of-life tests of the Phenix reactor. Objective of the present study is to assess the applicability of the NETFLOW++ code which has been verified thus far using various water facilities and validated using the plant data of the loop-type FBR “Monju” and the loop-type experimental fast reactor “Joyo”. The Phenix primary heat transport system is modeled based on the benchmark documents available from IAEA. The computation model consists of only the primary heat transport system with boundary conditions on the secondary-side of intermediate heat exchangers (IHX). The coolant temperature at the primary pump inlet, the primary coolant temperature at the IHX inlet and outlet, the secondary coolant temperatures and other parameters are calculated by the code where the heat transfer between the hot and cold pools is explicitly taken into account. A model including the secondary and tertiary systems was prepared, and the computed results also agree well with the measured data in general.