Tritium Release from Neutron-Irradiated Flibe Purged Out by Ar-H₂ or Ar at Controlled Temperature

Abstract

The rate of tritium released from temperature-controlled Flibe (a mixed molten salt of 2LiF + BeF₂) after neutron irradiation was determined comparatively under two different conditions of Ar-H₂ (10%) or Ar gas purge at a constant or linearly elevated temperature. Experimental rates of tritium release were analyzed based on its diffusion in Flibe and isotopic exchange between T atoms on surfaces and H atoms included in gaseous components. Gas released from Flibe had compositions of various ratios of HT to TF depending on the different conditions of Ar-H₂ or Ar purge gas. The major molecular species of tritium released from Flibe after neutron irradiation was HT under the condition of the Ar-H₂ purge and 300°C. The rate of tritium release under the Ar-H₂ purge was simulated well by the present analytical model. Although its chemical form immediately after the release was TF under the condition of Ar purge, it was changed to HT partly by interaction with metallic surfaces.