Tritium monitoring in the ITER neutral beam test facility

The operation of the proposed ITER neutral beam test facility involves the firing of a beam of deuterons into a calorimeter. The deuterons will become embedded in the calorimeter and subsequent particles can be involved in deuterium fusion reactions and the production of tritium. Complete tritium monitoring must encompass accurate measurement of the source term and all dispersal and discharge routes. Therefore, tritium monitoring must be provided both within and beyond the test cell. Monte-Carlo neutron transport calculations are used to show that the source term can be measured using a set of absolutely calibrated neutron counters. A range of monitoring devices are reviewed and recommendations are made for strategies in and around the facility and instrumentation for monitoring discharges to the stack and active drains, which can be met from existing commercial supplies, to measure the discharge and dispersal routes.