IAEA's coordinated research project on EBR-II Shutdown heat removal tests

A Coordinated Research Project (CRP) on “Benchmark Analysis of EBR-II Shutdown Heat Removal Tests (SHRT)” was launched by the International Atomic Energy Agency (IAEA) in 2012. A series of transient tests were conducted on the EBR-II reactor at Argonne National Laboratory (ANL) to improve the understanding of thermal hydraulics and neutronics of fast reactors. Shutdown heat removal tests conducted in 1984 and 1986 demonstrated mechanisms by which fast reactors can survive severe accident initiators with no core damage. Two SHRT tests, SHRT-17 representing Protected Loss of Flow (PLOF) transients and SHRT-45R representing Unprotected Loss of Flow (ULOF) transients, were studied in the IAEA CRP. The objectives of the CRP were to improve design and simulation capabilities in fast reactor thermal hydraulics, neutronics and safety analyses through benchmark analysis of these two important tests. At the first stage of the benchmark, ANL provided the input data on EBR-II geometry, as well as initial and boundary conditions for the SHRT-17 and SHRT-45R tests to perform “blind” calculations. At the second stage, ANL released the experimental observations and participants had the chance to analyze the difference and refine the models. At the third stage, a methodology to systematically analyze and compare the models and the results of each participant was applied. Nineteen organizations from eleven countries participated in the CRP, making it one of the largest CRP coordinated by the IAEA fast reactor team. The paper provides a general CRP overview, gives the basics of the EBR-II reactor design, describes the shutdown heat removal tests, the benchmark setup, and results of numerical simulations, followed by a detailed discussion on the EBR-II CRP.