LAUSR

Abstract Al–B4C metal matrix composites have been utilized as a neutron absorber for the past two decades to manage the neutron flux and the criticality of spent nuclear fuel pools. Recently, premature surface corrosion has been found from an eight-year-old surveillance coupon although 40 years of service life was guaranteed based on separated corrosion tests and gamma irradiation tests. Suspecting the premature corrosion was assisted by radiation damage effects from energetic particles emitted from 10B(n, α)7Li reaction, nanoscale characterization and neutron attenuation tests were carried out on the surveillance coupons used in a spent nuclear fuel pool for 33, 52, and 99 months to investigate the degradation mechanisms and 10B depletion. Highly radiation-damaged structures, such as numerous gas bubbles filled with helium and hydrogen in the aluminum matrix and microcracks in boron carbide particles, were observed from all absorber coupons with slightly reduced densities (