Development of a numerical simulation program for detailed thermal hydraulics in fast reactor fuel assembly, 12; Analysis of a fuel assembly with an inner duct structure

Kikuchi, Norihiro  ; Imai, Yasutomo*; Ohshima, Hiroyuki; Tanaka, Masaaki  

A computer program SPIRAL, which has been developed for detailed thermal-hydraulic analyses in a fuel assembly of sodium-cooled fast reactors, was applied to a preliminary analysis of an FAIDUS (Fuel Assembly with an Inner Duct Structure)-type fuel assembly for investigating the applicability of the program and clarifying thermal-hydraulic characteristics of FAIDUS. Numerical simulations were conducted for a FAIDUS-type 33-pins assembly in which 4-pins located at a corner of hexagonal wrapper tube were removed to simulate inner duct part and a 37-pins assembly without inner duct part (reference case). The comparison of two cases showed that the inner duct structure had limited effect on the temperature distribution in the fuel assembly and the pressure loss coefficient was mostly unchanged. Through the numerical simulations, the applicability of SPIRAL to the FAIDUS-type assembly was confirmed.