Contributions from the ACRR in-pile experiments to the understanding of key phenomena influencing unprotected loss of flow accident simulations in LMFBRs

This paper summarizes the recently terminated in-pile experiments in the Annular Core Research Reactor (ACRR) of the Sandia National Laboratories that have been performed to study the behavior of fast reactor fuel under different conditions during an unprotected loss of flow (ULOF) accident in an LMFBR. Three groups of experiments are covered. The FD + STAR tests that study the fuel disruption and initial fuel motion in voided regions, the TRAN experiments on flowing and freezing of molten fuel in structures, and the equation of state tests with fresh and irradiated fuel under prompt burst conditions. Conclusions are drawn on the contributions which the results from these tests make to the understanding and simulation of key phenomena under ULOF accident conditions in LMFBR's.