Radiological Assessment of Target Materials for Accelerator Transmutation of Waste Applications

Abstract

This paper provides the radiation absorbed dose rates (rad-h^-1) to a tissue-equivalent torus ring at 1 meter from radioactive spallation products in Ta, W, Pb, Bi, and LBE target materials used in Accelerator Transmutation of Waste (ATW) applications. No previous works have provided an estimate of the absorbed dose rates (rad-h^-1) to tissue from activated targets for ATW applications. In addition, this paper provides the characterization of target materials of high-energy particle accelerators for the parameters of (a) spallation neutron yield (neutrons/proton), (b) spallation products yield (nuclides/proton), (c) energy-dependent spallation neutron fluence distribution (n-cm^-2 MeV^-1), and (d) identification of the optimal target dimensions to yield the maximum radial spallation neutron leakage from the target. A beneficial characteristic of these target materials (Ta, W, Pb, Bi, and LBE) is they do not produce radioactive transuranic isotopes, which have very long half-lives and require special handling and disposition controls. In addition, these activated, spent targets are not considered high-level radioactive waste for disposal purposes such as spent fuel from a nuclear power reactor.