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 causes “blanketing” of the metal surface and subsequent operational problems. This paper reviews the operational procedures and results observed at Ontario Hydro's dispensing facilities. Experimental work performed to investigate the effect of this helium-3 on the reuse of the Amersham Mk IV pots demonstrated the necessity of an operational ability to evacuate the uranium pot at stages during the tritium transfer, without affecting the quantitative transfer measurement.