IMPACT OF HYDROGEN IN A FUSION-REACTOR ENVIRONMENT ON TITANIUM-ALLOYS

The impact of hydrogen in a fusion reactor on a titanium first wall and blanket structure has been investigated. Hydrogen is of concern in titanium because the combination of hydrogen isotopes in a fusion reactor and titanium's high affinity for hydrogen has the potential for producing hydrogen embrittlement and increasing the tritium inventory. The solubility of hydrogen in titanium depends upon a number of variables, chief of which is the type and amount of phase present, (alpha, beta, or alpha-beta). In this study the influence of alloying elements on phase stability and hydrogen solubility was investigated. The effects of three major sources of hydrogen were examined: (1) hydrogen produced via neutron transmutation reactions, (2) deuterium and tritium from the plasma chamber, and (3) tritium from the breeding material or coolant. Results indicate that under the conditions studied hydrogen from transmutation reactions does not raise the hydrogen concentration significantly above the level currently allowed in commercial alloys. However, significant amounts of deuterium and tritium can be absorbed in the first wall at the higher gas pressures encountered during the refueling cycle. The tritium concentrations anticipated with lithium or lithium oxide present, result in low tritium concentrations in titanium structures whereas tritium pressures anticipated for a lithium-lead breeding blanket may result in substantial tritium concentrations in a titanium structure. © 1979.