Limitation of Tritium Outgassing from Tritiated Solid Waste Drums

In the framework of the development of fusion thermonuclear reactors, tritiated solid waste is foreseen and will have to be managed. In France, the long-term management of all radioactive waste is under the responsibility of the national waste management agency (ANDRA), which sets out strict specifications on waste drums before their acceptances in disposal. Among all these specifications, the related ones for tritium concern limitations in terms of activity and tritium degassing. The latter is the subject of research developments to improve its control. The degassing tritium can be under the form of tritiated hydrogen, tritiated water and, in some specific cases, negligible amount of tritiated volatile organic compound. Hence, considering the major forms of degassing tritium, CEA has developed a mixed-compound dedicated to tritium trapping in drums. Based on several experiments, the foreseen mixed compound is composed of MnO_{2, Ag2O, Pt and molecular sieve, the three first species having the ability to convert tritiated hydrogen into tritiated water and the last one acting as a trap for tritiated water. This paper aims at describing the formulation of the mixed solids compound and presenting the first results of experimental lab-scale tests performed on purely tritiated waste confined in a small reactor. It is observed that the rate of tritium degassing from the reactor is reduced drastically during several months by means of the presence of the mixed compound.}