Experimental validation of numerical methods in a LeBENC code for single phase natural circulation modified for a fluoride salt-cooled high-temperature reactor (FHR) - 14190

The Fluoride salt-cooled High-temperature Reactor (FHR) is a Generation IV reactor class under consideration by the U.S. Department of Energy which combines many of the strong attributes of alternative reactor technologies. The FHR concept, like many Generation IV technologies, can respond in a fully passive mode to avoid core damage and subsequent major off site radiation release during severe accidents. Current passive decay heat removal simulation efforts for the FHR have relied on legacy light water reactor codes tuned for high-pressure two-phase flow accident conditions expected during loss of coolant accident scenarios. In this paper we present results from a 1-D single-phase natural circulation code and a validation plan based on the transients encountered in the decay heat removal system of an FHR: loss of heat sink (LOHS), start-up flow conditions, and a step change in power. The code, LeBENC, was originally developed by the Bhabha Atomic Research Centre (BARC) to simulate the natural circulation characteristics of lead-bismuth eutectic in a closed rectangular loop. Modifications have been made to the code to make it more suited to the decay heat removal system used in an FHR. An experimental natural circulation loop using the water as a simulant fluid is being built at the University of New Mexico to validate the numerical methods employed in this code. Results from this effort are presented. (authors)