Effect of coupon orientation on corrosion behaviour of aluminium alloy coupons in the sepent fuel storage section of the IEA-R1 research reactor

Abstract

Surveillance programmes to monitor the corrosion of aluminium clad spent research reactor fuels have used test racks containing horizontal metallic coupons. Spent MTR type fuel elements are usually stored vertically, with its fuel plates, also vertical. Hence, the influence of coupon orientation on the corrosion behaviour of aluminium alloy coupons exposed to the spent fuel storage section of the IEA-R1 research reactor in São Paulo, Brazil has been studied. Circular coupons of aluminium alloys AA 1050 and AA 6061, oriented both vertically and horizontally, were exposed to the storage section water for a year. Individual and coupled coupons were exposed to simulate general, crevice and galvanic corrosion. The storage section water parameters were periodically measured. Pitting was the main form of corrosion and coupon orientation had a marked effect on the extent of pitting. Vertically oriented coupons pitted less than horizontally oriented coupons.