Measurements of D-T neutron induced radioactivity in plasma-facing materials and their role in qualification of activation cross-section libraries and codes

USDOE/JAERI collaborative program on induced radioactivity measurements has been spread over last five years and has covered, among others, a large number of plasma facing materials of interest to D-T fusion reactors, including ITER and DEMO. The experiments have consisted of irradiation of high purity material samples in a range of neutron energy spectra in simulated fusion environments of prototypical blanket assemblies driven by D-T neutrons at FNS/JAERI. A typical sample measured 10 mm in diameter by 1 mm thickness, and the neutron fluence ranged from ∼1010 n/cm2 to ∼1014 n/cm2, over an irradiation period of 30 m and 10 h. The irradiated samples were then cooled for varying times, from ∼10 m to ∼3 weeks, and their activity was derived by counting associated γ-rays with intrinsic germanium detectors