Experimental estimation of radiation damage induced by 10B(n, α)7Li reactions in Al-B4C neutron absorber discharged from spent nuclear fuel pool

Abstract

Al-B4C neutron absorbers in spent fuel pools have been assumed to have negligible radiation damage and helium generation from 10B(n, α)7Li reactions. However, surveillance coupons have shown highly radiation-damaged microstructure. We conducted 200 keV He+ ion irradiation on Al 6061 at three different doses (0.1, 1, and 10 dpa) and compared the microstructures to the surveillance coupon. The neutron absorber's bubble size (25.9 ± 7.4 nm) was most similar to the 10 dpa irradiated specimen (28.4 ± 13.8 nm). Commercial neutron absorber (BORAL and MAXUS®) were also irradiated up to 10 dpa and showed preferential cavity formation along grain boundaries.