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a b s t r a c tAssessment of the thermodynamics of SiC corrosion under light water reactor coolant environments suggests that silica formation is always expected in the range of applicable pH and potential. Autoclave testing of SiC-based materials in the absence of ionizing radiation was performed. The kinetics data from these tests, when compared with kinetics of silica dissolution in water and post-exposure characterization of SiC samples, suggest that oxidation of SiC to form silica is the rate-limiting step for recession of SiC in high temperature water. Oxygen activity in water was determined to play an important role in SiC recession kinetics. A simplified model of a power loop shows the effect of silica dissolution from the hot region (resembling fuel) and deposition in the cold regions.

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Analysis Key information pertaining to fission product release Capsule components Cumulative inventory of fission products released from all fuel compacts in a capsule during irradiation Fuel compact gamma scanning Retained inventory of fission products in each individual fuel compact Deconsolidationleach-burn-leach Inventory of fission products retained in the compacts outside of the SiC layers Particle gamma counting Retained inventory of fission products in the particles 2.2.1. Analysis of irradiation capsule components for deposited fission products The major components of the irradiation capsules-including the metal shells and structural components, the graphite fuel holders, and graphite spacers at the ends of the capsules-were analyzed at INL to determine the cumulative inventories of fission products released from the compacts during the irradiation. As there were 12 compacts in each irradiation capsule, the data provide information on the total inventory of fission products released from all 12 fuel compacts; release from each compact cannot be derived from these data. The metal capsule shells were leached in acid to remove deposits. Analysis of the leach solutions included gamma spectrometry for gamma-emitting fission products, Sr separation and gas flow proportional counting for 90