Accelerated corrosion tests of Al-B4C neutron absorber used in spent nuclear fuel pool

Accelerated corrosion tests of Al-B4C neutron absorber, equivalent to 37 months in a spent nuclear fuel pool, were conducted on three different period-installed surveillance coupons (33, 52, and 92 months) to further investigate the underlying mechanisms of premature surface corrosion and 10B depletion which we had recently reported in another study. Microstructure characterization, electrochemical analysis, and neutron attenuation tests were conducted after the corrosion tests, and two types of galvanic corrosion, Al matrix/stainless steel and Al matrix/B4C particles, were discovered. The duplex oxide layer comprised of amorphous oxide and Al(OH)3 films and pit corrosion were also observed on the surface with reduced densities (< 1%). The neutron attenuation tests on the absorbers and ICP-MS measurement of the coolant showed no considerable change in 10B areal density.