The Handling, Assessment, Transport and Disposal of Tritiated Waste Materials at JET

Abstract

In November 1991 over 40TBq of tritium was introduced into the JET machine for the first tritium experiment (PTE). This tritium combined with neutron activated material forms the basis of radioactive waste at JET. In order to satisfy regulatory authorities and the operators of the repository to which JET consigns its radioactive waste, JET estimates the level of tritium in each consignment of waste removed from the site. All types of JET radioactive wastes are received for disposal at the Waste Handling Facility (WHF) which features a waste sorting and sampling station, a glove box, a compactor, and packaging and transfer systems. The WHF is operated as a contamination control area with monitored tritium discharges. The waste received includes solid, eg housekeeping waste, machine components and vessel wall tiles; and liquid, eg water, oils and freon containing a unique cocktail of radionuclides consisting 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 counters and ionisation chambers, and samples of various components and materials 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 assessed by a sniffing technique which has a limit of detection corresponding to 120Bq/g. The prospect of the introduction of more tritium during future tritium operations has led to the investigation of improved methods of tritium measurement and of component detritiation to facilitate future waste disposal.