Helium Charging of Metals by Tritium Decay

Abstract

AbstractThe results of a study on the use of the decay of tritium to helium as a method of charging metals with helium were presented. Tritium was dissolved into vanadium and niobium specimens at elevated temperatures, allowed to decay to helium at room temperature, and then removed from the given specimen by hot vacuum extraction. Post-high-temperature test 3He concentrations up to 500 appm were achieved and were found to agree within ±7% with tritium decay concentration calculations. Substantial ductility decreases were found in niobium specimens tested at 1020°C and containing >130 appm helium. The ductility losses appeared to correlate with the appearance of helium on the grain boundaries. A niobium specimen containing 170 appm helium and subjected to an 1800°C anneal exhibited a substantial loss of load-carrying grain-boundary area due to grain-boundary helium bubble formation.