Tritium decontamination of TFTR carbon tiles employing ultra violet light

Tritium decontamination on the surface of Tokamak Fusion Test Reactor (TFTR ) bumper limiter tiles used during the Deuterium-Deuterium (D-D) phase of T FTR operations was investigated employing an ultra violet light source with a mean wavelength of 172 nm and a maximum radiant intensity of 50 mW/cm(2) . The partial pressures of H-2, HD, C and CO2 during the UV exposure were e nhanced more than twice, compared to the partial pressures before UV exposu re. In comparison, the amount of O-2 decreased during the UV exposure and t he production of a small amount of O-3 was observed when the UV light was t urned on. Unlike the decontamination method of baking in air or oxygen, the UV exposure removed hydrogen isotopes from the tile to vacuum predominantl y in forms of gases of hydrogen isotopes. The tritium surface contamination on the tile in the area exposed to the UV light was reduced after the UV e xposure. The results show that the UV light with a wavelength of 172 nm can remove hydrogen isotopes from carbon-based tiles at the very surface. (C) 2001 Elsevier Science B.V. All rights reserved.