Neutronic analysis of ITER neutral beam test bed

The neutron dose arising during the operation of the ITER neutral beam test bed was calculated using the Monte-Carlo code MCNP. The activation of the injector components was determined using the inventory code FISPACT and the resultant gamma ray doses at the end of the test programme were determined. It is found that there would be a neutron dose during beam operations sufficient to entail restricted and monitored access to areas outside the shield wall. A careful assessment of the shielding is needed. The individual components of the injector are generally not activated excessively, i.e. their activation levels fall below the hands on limit within 1 year. However, the total gamma dose close to the vessel is substantially higher than any individual contact dose. This must be taken into consideration in maintenance planning.