AbstractJET has completed its first stage of active operations, processing more than 100 g of tritium during the deuterium–tritium experiment (DTE1), the neutral beam intervention and remote tile exchange shutdown. The radiological safety of tritium handling operations has been of particular interest. A wide range of tritium operations has been carried out in the period 1995–1998. This paper describes some of the radiological protection measures for work with tritium, and discusses Health Physics operational experience of handling tritium in this period. Descriptions are given of active operations in the gas handling plant; in the torus hall during DTE1; in related interventions, and of the remote exchange of in-vessel divertor modules. Workplace contamination levels over 100 DAC (HTO) have been encountered, tritiated water with activity of 2 TBq/l and tritiated carbon with activities of ∼4 TBq/g has been handled. Control measures involving the use of purge and extract ventilation, and of personal protection using air-fed pressurised suits are described. The project imposes tight limits on radiation exposures. Tritium doses to staff in this period have been very low (individual doses <170 μSv/year, collective doses ≤2.1 mSv/year). Aerial discharges have been <3% of annual authorised limits, and average environmental (HTO) levels have been a few Bq/m3. Lessons have been learnt concerning exposure control, large-scale permeation effects, and the appearance of residual tritium on exposed surfaces. Tritium operations at JET have been conducted without incident and with very low personnel exposures. The methodology of using containment and ventilation systems and tight radiological control has been successful in limiting doses. JET experience shows that large-scale tritium handling and exposure control can be achieved within stringent dose limits.
ICRH operations during the JET tritium and DTE2 campaigns