Development of EASY to include sequential charged particle reactions and examples of its use with realistic materials

A new version of the European Activation System (EASY), which includes the European Activation File (EAF) and the inventory codes FISPACT, has recently been developed. This version offers the possibility to calculate the effect of sequential charged particle reactions (SCPR), i.e., reactions of the charged particles produced by the primary neutron reactions. Such reactions were shown to be significant for pure materials. Some question remains as to their importance for realistic alloys with impurities. This paper describes the new features in EASY4 and reports results of calculations on a collection of fusion-relevant materials. Highlights from the conclusions are: (i) it is essential that correct impurity levels in materials be specified in order that activation properties can be determined; (ii) for realistic fusion-relevant materials studied here the effect of SCPR is unimportant compared with the estimated uncertainties in the dose rate; (iii) if special care were taken with impurity control in structural materials such as vanadium alloys and breeding materials such as FLiBe it would be necessary to include SCPR in inventory calculations for accurate predictions; in the case of iron-based alloys the contribution from SCPR is negligible even when no impurities are included. 9 refs, 4 figs, 2 tabs