Radioactivity Induced in A Theta-Pinch Fusion Reactor

Induced radioactivity and afterheat in fusion reactor blanket structures and magnetic coils are essential inputs for environmental impact studies. These quantities have been calculated for a reference theta-pinch reactor (RTPR) and compared with results reported for other fusion reactors and typical fast fission reactors. Major indepen-dent variables considered in the RTPR analysis were structural material (Nb—1% Zr, V—20% Ti), 14.1-MeV neutron wall loading (0.2 to 6.7 MW/m²), operating time (1 to 20 yr) and time after shutdown (0 to 30 000 yr). For a given operating time large radioactivity contributions from ⁹⁵Nb render higher [Ci/W(th)J and {Ci/[W(th)yr]} values at higher wall loadings and <1 yr after shutdown. At long times after shutdown this dependence is reversed and represents an advantage relative to long-term radwaste storage. Activity from V— 20% Ti is insensitive to wall loading or operating time. For either material, afterheat power densities are about two orders of magnitude lower than for fission reactors.