Comparing the effects of various (p,xn) radionuclide production routes on induced radioactivity in the concrete walls of a cyclotron vault.

In sum, 11 (p,xn) related nuclear reactions with 9 target materials, namely 18O(p,n)18F, 15N(p,n)15O, 68Zn(p,n)68Ga, 68Zn(p,2n)67Ga, 69Ga(p,2n)68Ge, 89Y(p,n)89Zr, 100Mo(p,pn)99Mo, 100Mo(p,2n)99mTc, 112Cd(p,2n)111In, 124Xe(p,2n)123Cs and 203Tl(p,3n)201Pb, are involved in the operation of 13 radionuclide-production cyclotrons in Taiwan. The secondary neutrons accompanying these production routes could induce varying degrees of material activation in the cyclotron facility. Accordingly, this study compared the effects of various (p,xn) production routes on the neutron-induced long-lived radioactivity in the concrete walls of a hypothetical cyclotron vault. In addition, an activation-reduction approach involving the addition of a layer of neutron-absorbing material to the surface of inner concrete walls was evaluated.