OPERATIONAL PROBLEMS WITH URANIUM POTS DUE TO HELIUM BLANKETING

Extensive experience with the refilling of the Amersham Mk IV 1.85 PBq uranium pots has shown that helium-3 resident in the uranium matrix c auses ''blanketing'' of the metal surface and subsequent operational p roblems. This paper reviews the operational procedures and results obs erved at Ontario Hydro's dispensing facilities. Experimental work perf ormed to investigate the effect of this helium-3 on the reuse of the A mersham Mk IV pots demonstrated the necessity of an operational abilit y to evacuate the uranium pot at stages during the tritium transfer, w ithout affecting the quantitative transfer measurement.