Thermal-hydraulic analysis of EBR-II Shutdown Heat Removal Tests SHRT-17 and SHRT-45R

As one of the six Generation-IV reactors, SFR (sodium-cooled fast reactor) is attracting more and more attention in recent years. To evaluate the SFR safety characteristics, the Shutdown Heat Removal Tests (SHRT) conducted by Argonne National Laboratory (ANL) were performed in Experimental Breeder Reactor-II (EBR-II) to verify inhere safety characteristics. To find the inaccuracies in the exist models and improve the simulating level for SFR, SHRT-17 and SHRT-45R have been chosen as the benchmark problems for the IAEA coordinated research project (CRP), which we have participated in. THACS (the Transient Thermal-Hydraulic Code for Analysis of Sodium Cooled Fast Reactor) developed by XJTU was used in our work. THACS has finished preliminary with completion of all the models of primary loop originally intended for simulating accidents in SFRs. THACS is a multi-channel, multi-phase, multi-component transient and universal code coupled with the point reactor kinetics model. In this paper the models of THACS were introduced in detail and SHRT scenario simulation work of EBR-II has been performed. THACS was verified with the simulation results of flowrate and temperatures in core and instrumented subassembly XX09. After the verification, the peak coolant, cladding and fuel temperatures were estimated which is under the safety limits. Results show that EBR-II is effective in protecting the reactor against the severe loss-of-flow accidents. The three-layer model for cold pool coupled with THACS was used and the predicted results in a better agreement with the measurements.