The ITER first wall as a source of photo-neutrons

The beryllium coverage of the ITER first wall is a source of two kinds of photo-neutrons in the plasma chamber: prompt photo-neutrons during the D-T-operation and delayed photo-neutrons after shutdown. They do not essentially change the radiation conditions either inside or outside the bulk radiation shield. However, the prompt photo-neutron emission ∼2×1016 n/s and non-zero delayed photo-neutron fluxes ∼105–108 cm−2 s−1, their spectra and possible effects, estimated in the paper, should be taken into account in diagnostics, maintenance and storage considerations.