We have conducted electrochemical experiments with several multi-phase alloy and alloy/ceramic composite materials representing waste forms that are being developed for metallic high-level radioactive waste streams generated during the pyroprocessing of spent nuclear fuel. The waste streams are dominated by contaminated steel cladding with Zr and small amounts of noble metal fission products from the fuel. The predominant alloy phases that form are FeCrMo-based intermetallics that host Tc and FeZrNi-based intermetallics that host actinide fuel wastes. An experimental protocol was developed to quantify the corrosion behavior as a function of key environmental variables. The protocol consists of potentiostatic electrochemical tests with periodic EIS measurements combined with microscopy and solution analyses. The experimental approach is described and representative test results are presented to show how the test results are being used to parameterize the model developed to predict long-term waste form performance in a disposal system.

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