Experimental investigation of radioactivities induced in fusion reactor structural materials by 14-MeV neutrons

The aim of the present study is the experimental validation of European activation system (EASY-97) for structural materials irradiated with 14-MeV neutrons. Samples of the stainless steel 316 (AISI 316 LN (IG)), which is the structural material of international thermonuclear experimental reactor (ITER), of the low-activation steels MANET and F82H and of the vanadium alloys V–3Ti–lSi, V–4Ti–4Cr and V–5Ti–2Cr were used for benchmarks. Pieces having the mass of ≈l g were irradiated at the high-intensity neutron generator SNEG-13 at Sergiev Posad with neutrons of 14.93 and 14.37 MeV mean energy. Fluences applied were of the order of 1014 cm−2. γ-Spectra of the samples were measured several times during the decay up to about 1-year. The activities of 27 different radionuclides, identified by γ-energies and half-life, were determined. Their half-lives range from a few min up to 5.3 years. For each of the measured values the activity was calculated with EASY-97, and calculated-to-experimental values (C/E) were determined. If the uncertainty of the C/E is estimated with both the experimental errors and the calculational one, including cross-section as well as half-life uncertainties, validation of EASY-97 can be stated for most of the activities. The pathways of production are analysed for all activities, and the corresponding cross-sections are discussed if larger deviations were observed.