Fusion Programme - ENEA - Fusione

3. Technology Programme2007 Progress Reportbetter results. The resulting dose rate is mainly due to gammas emitted by cobalt isotopes (Co–60 andCo–58). These radionuclides are produced by neutron reactions with predominantly nickel and cobalt. Theobserved underestimation could be due to the fact that some components that contain these elements areabsent in the description of the model.The neutron-induced decay heat on samples of rhenium irradiated at the FrascatiExperimentalneutron generator (FNG) in a FW-like neutron spectrum was measured (Europeanvalidation of neutron Activation File [EAF] Project). Two thin rhenium samples (25 mm) were irradiatedcross sections for for 12360 s. One sample was monitored by ENEA’s decay heat measuringfusion-relevantsystem where gamma and beta decay heats are simultaneously measured. Thematerialsother sample was monitored by HPGe detectors. The radionuclides producedwere identified through gamma spectroscopy. The decay times studied werefrom a few minutes up to about one month after the irradiation. The European Activation System (EASY)calculations were carried out with the use of EAF 2005.1.The results and uncertainties of the comparison between experimental data and EASY predictions(fig. 3.33) give confidence in the accuracy of the EASY code in predicting induced decay heat for a fusionreactor such as ITER. A discrepancy (C/E=0.65±0.1 exp err.) found in the decay heat for medium decaytime was identified as being due to the reactions Re187(n,g)Re188. This nuclide is responsible for about90% of the heat produced for a decay time