Safety scenario and integrated thermofluid test

The largest mobilizable radioactive material inventory in the form of tritium and activated dust in a fusion reactor is estimated to be located in the vacuum vessel. The accident scenarios of postulated thermofluid transients such as ingress of coolant inside the vacuum vessel and the loss of vacuum boundary leading to the release of radioactive material are introduced. The accuracy of the present analysis method and database for evaluating the radioactive material release in such accident scenarios is assessed. The areas where the data and methods seem to be most uncertain are identified, such as the condensation of steam under vacuum condition, the activated dust mobilization and transport in and out of the vacuum vessel in the event of the transients. An approach to experimentally reduce such uncertainties in the evaluation of radioactive material release are presented. A combination of a number of specific test devices to reduce uncertainties in such areas as dust mobilization and transport, and an integrated thermofluid test facility to establish the evaluation methodology are proposed.