EXPERIMENTAL AND MODELING STUDIES ON THE EXPOSURE OF WALL SURFACES TOTRITIUM GAS IN AMBIENT ROOM CONDITIONS

An experimental set-up is used to carry out static exposure tests to s tudy the uptake and oxidation of tritium released in ambient room air, routinely or accidentally, in the presence of selected surface materi als. Tritium, in its elemental form at concentrations of the order of similar to 0.4 GBq/m(3) (10(-2) Ci/m(3)), is injected into the glass e xposure chamber containing the selected surface material and air at at mospheric pressure. Periodically, samples of the chamber atmosphere ar e analysed, using liquid scintillation counting, to obtain the concent rations of HTO and T-2. The exposures have been performed using alumin ium, 316L stainless steel and painted stainless steel plates, as the s elected surface materials. Results are compared with predictions using the ITER approved TMAP4 code. The results indicate practically the sa me conversion rate, of about 0.02% per day, for both the aluminium and stainless steel samples and give reasonable agreement with modelling predictions. Strong absorbtion of both T, and HTO by the painted surfa ce is observed, suggesting the use of high values for the solubility c onstant to correctly predict this behaviour.