Reduction of the induced radioactivity in an ADS target by changing the target material isotope composition

In the paper a possibility of using in a target of an accelerator driven system (ADS) a modified lead–bismuth eutectic (LBE) in which natural lead (Pb-nat) is replaced by a lead isotope, Pb-208, is considered. Spectra of neutrons inside and outside the target consisted from the modified LBEs, Pb-208(80%)–Bi(20%) and Pb-208(90%)–Bi(10%), are calculated using Monte Carlo code. It is shown that in such the targets a harder spectrum of neutrons is realized as compared with the spectrum of the conventional target LBE, Pb-nat(45%)–Bi(55%). The induced activity of such the modified LBE target is reduced due to depleting the material with neutrons of intermediate energy, 10–100 keV and reducing a share of bismuth in the LBE from 55% down to 10–20%.