The corrosion of materials in water irradiated by 800 MeV protons

A method for measuring the real-time corrosion rates for Alloy 718, stainless steels (SS) 304L and 316L nuclear grade (NG), aluminum alloys 5052 (Al5052) and 6061 (Al6061), copper (Cu), tantalum (Ta), and tungsten (W) in two separate water systems that were irradiated by 800 MeV protons is presented. The first water system was fabricated entirely of 304 SS, thoroughly cleaned before operation, and employed hydrogen water chemistry (HWC) to mitigate the formation of some of the radiolysis products. The samples were adequately shielded from the irradiation cavity such that only the effects of water chemistry were investigated. Over the course of that irradiation period the corrosion rates for 304L SS, 316L-NG SS, Ahoy 718, and Ta were less than 0.12 mu m/yr. For Al6061 and Al5052, the corrosion rates were of the order of 0.50-2.0 mu m/yr. The corrosion rate of W was relatively high between 5.0 and 30 mu m/yr. The second water system, fabricated from copper piping and steel components, was not cleaned prior to operation, and employed no HWC. In comparison to the other system, the corrosion rates in the copper/steel system were 1-3 orders of magnitude higher. These results are discussed in terms of water radiolysis and water impurity levels. (C) 2000 Elsevier Science B.V. All rights reserved.