The Corrosion of Aluminium Alloy and Release of Intermetallic Particles in Nuclear Reactor Emergency Core Coolant: Implications for Clogging of Sump Strainers

다국어 초록 (Multilingual Abstract)

Clogging of sump strainers that filter the recirculation water in containment after a loss-of-coolant accident(LOCA) seriously impedes the continued cooling of nuclear reactor cores. In experiments examiningthe corrosion of aluminium alloy 6061, a common material in containment equipment, in boratedsolutions simulating the water chemistry of sump water after a LOCA, we found that Fe-bearing intermetallicparticles, which were initially buried in the Al matrix, were progressively exposed as corrosioncontinued. Their cathodic nature vis- a-vis the Al matrix provoked continuous trenching around themuntil they were finally released into the test solution. Such particles released from Al alloy components ina reactor containment after a LOCA will be transported to the sump entrance with the recirculation flowand trapped by the debris bed that typically forms on the strainer surface, potentially aggravatingstrainer clogging. These Fe-bearing intermetallic particles, many of which had a rod or thin strip-likegeometry, were identified to be mainly the cubic phase ac-Al(Fe,Mn)Si with an average size of about2.15 mm; 11.5 g of particles with a volume of about 3.2 cm3 would be released with the dissolution ofevery 1 kg 6061 aluminium alloy.

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