Details of in situ sample retrievals and test completion for the materials interface interactions test (MIIT)

The Materials Interface Interaction Tests (MIIT) program involves the comparative, performance-evaluation testing of multiple U.S. and foreign nuclear waste glasses (nonradioactive), potential canister and overpack metals, brine, an geologic materials in the rock salt repository environment at the Waste Isolation Pilot Plant (WIPP) facility. About 2000 materials specimens were emplaced onto 50 tests assemblies and exposed them to a 90 ± 10 degrees C salt-brine environment. The in situ conduct of the MIIT was successfully concluded after five years and retrieved all samples for posttest laboratory analysis. These 5-year glass and metal samples, along with samples previously retrieved after 0.5, 1, and 2 years, are being analyzed in multiple international laboratories, in a cooperative testing effort. The focus in this paper is to summarize technical details and repository relevant observations on the in situ conduct, sampling, and termination operations of the MIIT. Such information should be useful for the interpretation of the laboratory-based analysis and also relevant for other organizations planning or conducting similar materials-related, in situ tests. 12 refs., 1 fig