Inter-subassembly heat transfer of sodium cooled fast reactors; Validation of the NETFLOW code

Mochizuki, Hiroyasu

This paper describes an applicability of the NETFLOW code for prediction of temperature at the exit of subassemblies of a sodium cooled fast reactor. So far, this code has been validated using data obtained at facilities and reactors of which coolants are water or sodium. A natural circulation test was conducted in the "Joyo" reactor with a 100 MW irradiation core, and a turbine trip test at "Monju". These tests were chosen to validate a model to calculate inter-subassembly heat transfer. Through a calculation for the natural circulation of "Joyo", a model to calculate heat transfer in radial direction of the inter-subassemblies gave the reasonable sodium temperatures at the exit of subassemblies. Good agreements were also obtained in prediction of temperatures of "Monju". It was shown that the NETFLOW could evaluate temperatures at the exit of the subassemblies with the inter-subassembly heat transfer model without heat transfer by inter-wrapper flow.