2003 Seattle Annual Meeting (November 2–5, 2003)

Paper No. 4
Presentation Time: 1:30 PM-5:30 PM


ALBRIGHT, Amanda L., Dept. of Geological Sciences, Virginia Polytechnic Institute and State Univ, 4044 Derring Hall, Blacksburg, VA 24061 and RIMSTIDT, J. Donald, Geological Sciences, Virginia Polytechnic and State Univ, 4044 Derring Hall, Blacksburg, VA 24061, amalbrig@vt.edu

We have developed a test to simulate corrosion processes that might occur when pore water or modifications thereof drips onto a high-level radioactive waste canister. Alloy C-22 has been chosen by the U.S. Department of Energy as the construction material for the outer cylinders of the waste packages used to permanently store high-level radioactive waste in the vadose zone at Yucca Mountain. Our study focuses on looking at the corrosion behavior of C-22 in simulated fluids that might occur in the repository. C-22 is a hastelloy made of primarily nickel, chromium, and molybdenum with small amounts of iron, tungsten, and manganese. C-22 has been shown to be exceptionally corrosion-resistant. However, dripping of pore water or pore water distillation products onto spots on the canister surface can produce unusual phenomena not typically observed in conventional corrosion tests.


The test consists of a bent strip of C-22 alloy heated from below while solution is dripped onto the surface of the strip from above. Because the experiment functions as a mixed flow reactor, the corrosion rate can be determined by analyzing the effluent for concentrations of nickel, iron, and chromium. For example, dripping 0.5 m nitric acid, which might form under these conditions as a result of the distillation of pore water solutions and radiolysis, onto a test strip heated to 120°C produces a corrosion rate of 1.2 mils per year. Conversely, J-13 groundwater dripped onto the surface produces a strongly adherent precipitate that coats the surface and no measurable release of Ni, Cr, or Fe. J-13 groundwater has been a standard test water in the DOE program, but it only occurs below the level of the proposed repository.