THE HANDLING, ASSESSMENT, TRANSPORT AND DISPOSAL OF TRITIATED WASTE MATERIALS AT JET

In November 1991 over 40TBq of tritium was introduced into the JET mac hine for the first tritium experiment (PTE). This tritium combined wit h neutron activated material forms the basis of radioactive waste at J ET. In order to satisfy regulatory authorities and the operators of th e repository to which JET consigns its radioactive waste, JET estimate s the level of tritium in each consignment of waste removed from the s ite. All types of JET radioactive wastes are received for disposal at the Waste Handling Facility (WHF) which features a waste sorting and s ampling station, a glove box, a compactor, and packaging and transfer systems. The WHF is operated as a contamination control area with moni tored tritium discharges. The waste received includes solid, eg housek eeping waste, machine components and vessel wall tiles; and liquid, eg water, oils and freon containing a unique cocktail of radionuclides c onsisting of tritium as a contaminant and neutron activated material. The tritium contamination may be in the form of gas, tritiated vapour or tritiated particulate with a specific activity up to 2.5MBq/g. The two main types of tritium monitors used are liquid scintillation count ers and ionisation chambers, and samples of various components and mat erials have now been assessed for tritium. The results so far indicate a widespread of tritium levels from 2Bq/g for cold gas transfer lines to 200kBq/g for in-vessel tiles. General soft housekeeping waste is a ssessed by a sniffing technique which has a limit of detection corresp onding to 120Bq/g. The prospect of the introduction of more tritium du ring future tritium operations has led to the investigation of improve d methods of tritium measurement and of component detritiation to faci litate future waste disposal.