Abstract
Experiments to measure radioactivity were carried out within the framework of the USDOE/JAERI collaborative program on fusion neutronics. High purity samples of a large number of materials of interest to designers were irradiated at various locations inside a number of prototypical assemblies driven by D-T neutrons. The isotopic activity of γ-emitting radioactive products was then measured and compared to calculations done using activation cross-section libraries of leading radioactivity codes like ACT4, DKR-ICF, RACC and REAC-3. Comparison of calculation C to experiment E of isotopic activities of the irradiated materials shows large variation in C/E ratios for most of the measured isotopic activities. A theoretical approach is outlined to obtain C/E for decay heat for elements and alloys from C/E's of measured isotopic activities of the elemental components. The application of this approach is then demonstrated by obtaining C/E's for PCA, V-15Cr-5Ti, HT-9, modified HT-9 and eight elemental components comprising titanium, vanadium, chromium, manganese, iron, cobalt, nickel, and molybdenum.