Activation analysis for the Ignitor tokamak

The purpose of the Ignitor experiment is to produce DT plasma regimes where ignition can take place. From the neutronics point of view, after a first period of machine set up and tuning in aneutronic operation, a second phase of 2.5 MeV neutron production with pure deuterium plasmas at increasing de nsity is anticipated. After that, a transition phase to increasing percenta ge of tritium will be followed by several years of operations with 50% of t ritium leading to short but intense 14-MeV neutron emission. To deal with t he concerns due to the strong neutron emission, a detailed description of t he actual Ignitor machine is implemented in the MCNP-4B Monte Carlo code to calculate the neutron fluxes in all machine components, taking in account the streaming through the ports. These fluxes are then used as input for th e FISPACT-97 code for the analysis of the activation at the end of life and at intermediate times for safety assessment purposes. The resulting dose r ate outside the device is also studied. The results point out that remote h andling is needed for repair/maintenance of inner components following the DD operations, and that the access in the hall near the device could be res tricted from the beginning of DT operations. The requirements on additional shield are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.