SAFETY ANALYSIS FOR THE MAINTENANCE OF THE CALORIMETER OF THE FIRST ITER NEUTRALBEAM INJECTOR

摘要

The Neutral Beam (NB) devices for the InternationalrnThermonuclear Experimental Reactor (ITER) are mediumrnenergy light particle accelerators. Accelerated particlesrnare negative deuterium ions with maximum energy of 1rnMeV. The deuteron beam with a pulse current of 40 A andrna duration time of 20 s is stopped on a water-copper alloyrncalorimeter.rnThe main features of the NBs will be tested in a TestrnFacility (NBTF) that will be built in a different site fromrnthat of ITER.rnIn the work presented here the assessment of thernradiological safety for the maintenance of the calorimeterrnof the NBTF is described and the related results arerndiscussed. The activation analysis of NBTF components isrnperformed using MCNP Monte Carlo Code and FISPACTrninventory Code in order to predict shutdown dose rates.rnStarting from a refined description of the D-D neutronrnsource, the induced activation of the NBTF components isrncalculated, for two realistic operational scenarios.rnNormal maintenance activities for the calorimeter arernidentified and the related operator positions are defined.rnFinally individual and collective doses are assessed forrnthe whole maintenance operation.