Neutronics experiment on a mock-up of the ITER shielding blanket at the Frascati Neutron Generator

An integral bulk shield experiment has been performed at the Frascati Neutr on Generator (FNG) with the main objective to validate the ITER shielding s ystem. To this end, a suitable mock-up of the ITER inboard shielding system including first wall, shielding blanket, vacuum Vessel and toroidal field coil, had been assembled at ENEA Frascati. Neutron and gamma-ray spectra as well as various nuclear responses were measured inside this mock-up when i rradiated by 14-MeV neutrons. Measured and calculated data were compared to validate transport codes and nuclear data used in the design of the ITER s ystem. In particular, the measured neutron and gamma-spectra, reaction rate s and the nuclear heating were compared with the same quantities calculated with the MCNP Monte Carlo code using the Fusion Evaluated Nuclear Data Lib rary (FENDL)-1.0 and the European Fusion File (EFF)-3.0 neutron cross secti on data. The neutron-induced activation measured in stainless steel was com pared with calculations performed with the FISPACT code and using the most recent activation cross section data file FENDL/A-2.0. The paper includes a comparison of calculated over measured quantities (CIE) and a discussion o f their relevance to the ITER nuclear design. It is found that, generally, the measured nuclear quantities are predicted by FENDL-1.0 and EFF-3.0 calc ulations within an uncertainty margin of about +/- 15% in the shielding bla nket and vacuum vessel, and +/- 30% up to the region of the toroidal field coil. (C) 1999 Elsevier Science S.A. All rights reserved.