Protons as a Potential Source of Radioactivity in D-³He Reactors

A wide range of experimental radionuclide production cross sections has been collected for protons with energies similar to those protons produced in a D-³He fusion reactor. Proton energy-dependent cross sections (E_p ≤ 14.7 MeV) were used along with the proton stopping data of Anderson and Ziegler to produce a proton-induced thick-target radionuclide activation yield library. The library is linked to a computer program that calculates proton-induced radioactivity. Another potential source of radioactivity considered is the activity induced by neutrons produced from proton interactions with the reactor structure through (p, n) reactions. A computer program that evaluates the energy spectrum of these neutrons has been developed. The thick-target yield library and its associated programs have been used in an activation analysis study aimed at investigating the effect of proton-induced activity on the total level of radioactivity generated in Apollo-L2, a D-3He tokamak fusion power reactor. The proton-induced activity was more than two orders of magnitude less than the activity induced by the fusion neutrons at shutdown and more than one order of magnitude less ∼1 day after shutdown. The level of radioactivity induced by the (p, n) neutrons was found to be two to three orders of magnitude less than fusion neutron-induced radioactivity at any time following shutdown.