This report describes the experimental work performed at Argonne National Laboratory (ANL) during fiscal year 2004 (FY 04) under the Bechtel SAIC Company, LLC (BSC) Memorandum Purchase Order (MPO), contract number B004210CM3X. Important results related to the technical bases, uncertainties, validation, and conservatism in current source term models are summarized below. An examination of specimens of commercial spent nuclear fuel (CSNF) that had been subjected to corrosion testing for up to 10 years under hydrologically unsaturated conditions was undertaken to elucidate radionuclide release pathways and mechanisms.