Neutronics and nuclear data issues in ITER and their validation

Neutron benchmark experiments carried out at 14 MeV neutron generators on ITER relevant materials and components have provided validation of nuclear data used in shielding and activation calculations for ITER, as well as an assessment of the related uncertainties. Further validation activity is still needed which could be performed in ITER, especially for activation cross sections, for dose rate calculations and for tritium production rates. In particular, concerning the nuclear performance of breeder blankets to be tested in ITER, the paper discusses the extensive preparatory work, to be carried out in a coordinated way among the participating Parties, required to finalize the design of neutronics Test Blanket Modules (TBMs), so that these tests can provide a complete and comparable, therefore useful, picture of the different concepts. Neutronics experiments being carried out at neutron generators on TBM mock-ups are providing important results on the quality of relevant neutron cross sections and for the preparation of the measurement techniques.