Liquid Salt Test Loop modeling using TRACE

Highlights: • The Liquid Salt Test Loop (LSTL) has been modeled using the TRACE code. • Flow correlations through a pebble bed have been identified and implemented in TRACE. • LSTL operational and transient conditions have been simulated. • The model helped to characterize the loop shakedown testing results. - Abstract: The objective of this work is to simulate the Liquid Salt Test Loop (LSTL) using the TRACE system code. The LSTL is an experimental facility built at Oak Ridge National Laboratory to test the thermal-hydraulic behavior of a circulating FLiNaK liquid salt. A literature review of the experimental work and the heat transfer and friction correlations for pebble beds was performed to identify the correlations that can be used to simulate the flow of FLiNaK through a pebble bed. The selected correlations were implemented in the TRACE source code and tested using 1-D pipe components. The modified version of TRACE was then used to develop models for each component in the loop. Each component was tested separately to assess its correct physical behavior. The components were integrated into a comprehensive loop model, including the main loop and the air cooling system. The model was used to compute the steady state conditions of the loop, in particular calculation of the pressure distribution and other global operational parameters. The loop-filling transient was analyzed, along with other specific transient conditions such as the pump trip and the loop behavior under natural circulation conditions. The TRACE model was used to help characterize loop thermal hydraulic behavior and to help interpret results from loop shakedown testing.