Compatibility of Li2O in a flowing helium environment

The objective of this task is to evaluate the compatibility of solid breeder materials with structural alloys in a flowing helium environment. The interactions between breeder material, alloys, and gas are investigated as a function of temperature, time, and environmental parameters (e.g., different H2O and H2 contents in helium). Reaction rates are determined by measuring the weight change of the breeder material with the alloys as well as the thickness of the reaction scales on the alloys. These measurements, coupled with metallographic evaluation of the alloy surfaces, are used to establish the mechanisms and rate-controlling processes for the corrosion reactions. Sintered Li2O pellets exposed to flowing helium containing 1 ppm each of H2O and H2 show weight losses at 550 and 6500C and a weight gain at 4500C. The rates of weight loss are approx.3 orders of magnitude greater than those predicted from equilibrium reaction kinetics. 6 references, 1 figure, 1 table