Monte-Carlo calculations of the activation of the accelerator target holder and shadow cone during the calibration of the ITER diagnostic devices with monoenergetic neutrons

Abstract The ITER International Fusion Energy Organization has solicited IRSN Laboratory for Neutron Metrology and Dosimetry to study the possibility to calibrate, in monoenergetic neutron fields at 14 and 2.45 MeV, the neutron detectors to be placed inside the future fusion reactor. In addition to the estimate of the necessary irradiation times, the dose equivalent rates from some of the neutron activated beam line elements had been calculated to consider the cooling time mandatory before access. Neutron activation calculations have been performed with the Fluka Monte-Carlo code. The resulting dose equivalent rates depend strongly of the neutron beam intensity as well as the neutron energy. In the worst case, for 14 MeV neutrons at an emission rate of 10 12  s −1 , a cooling time of 24 h would be needed for a close access to the shadow cone. Several days would be mandatory in the case of the target holder.