Tritium outgassing from solid waste

Waste disposal costs and volumes of waste produced in large scale tritium facilities point towards the need for categorizing the waste by level of activity and for reducing the quantity of waste sent to the facility. Reliable, labour minimized techniques for measuring the total activity contained within each waste parcel destined for a waste storage facility underpin the viability of this goal. A program examining the feasibility of classifying and discriminating the various types of tritiated waste through outgassing is underway. The types of waste examined are metal and non-metal. The metallic waste consists of stainless steel, copper and aluminium which have been used in tritium systems. The non-metallic waste consists of vinyl gloves and paper products generated on a daily basis in our laboratory. An effort is made to correlate the global outgassing rates with the tritium inventory in the waste. The tritium inventory is estimated by soaking selected waste components and counting the activity of the leachant. The outgassed tritiated species are tracked by pulling air through the waste bag into a water bubbler with a pump. Water soluble species are then trapped within the bubbler. Outgassing rates of >0.1 nCi/day are detectable in our experiment. Outgassing rates ranging from ~1 to 2000 nCi/kg.day are measured. Waste inventories varied from ~1 to 1000 μCi