Emulation of Radiation Damage in Neutron Absorber under Dry Storage Environments

Abstract

INTRODUCTION The Al-B4C metal matrix composite (MMC) type neutron absorber has been widely used in temporary and interim storage of spent nuclear fuel (SNF) to maintain neutron flux and criticality below safety regulatory limit. Expansion and extension of neutron absorber application become inevitable due to delay in SNF final disposal in few nuclear power generating countries. However, unexpected premature degradation has been reported from surveillance coupons of a Al-B4C absorber used in spent nuclear fuel pools (SFPs) [1]. Numerous helium bubbles observed at the interface between Al matrix and B4C particles suggested 10 B(n, α)7Li reactions as the major radiation damage mechanism [1].Radiation damage induced by 10B(n, α)7Li reaction in the neutron absorber during dry SNF storage (at high temperature) has not yet been extensively studied. In this study, radiation damage in Al-B4C neutron absorber was experimentally emulated by utilizing in-situ high-temperature heavy ion beam irradiation with exponentially increasing dose levels up to 1 displacement per atom (dpa) at high temperatures up to 400 °C.