Radiation damage calculations for charged particle emission nuclear reactions

Taking the quantum tunneling and Coulomb barrier into account, the present work proposes the calculation of Primary Knock-on Atom (PKA) energy for charged particle emission reactions. The method proposed in this paper and that used in NJOY have a large difference of PKA energy for charged particle emissions. For a D+T fusion neutron-induced Li-6(n,t)He-4 PKA, the maximum PKA energy calculated with NJOY is 2.9 MeV, whereas 14.2 MeV is obtained with the formula proposed in the present work. The subsequent total neutron-induced Displacement per Atom (DPA) calculated with the two methods has a small difference for most isotopes of which the DPA is predominated by neutron scattering reactions, such as Fe-56 and Ni-58. However, the difference can be important for nuclei with charged particle emission channels open at thermal energy, such as Li-6, B-10, and Ni-59. Using the damage cross sections (calculated by NJOY with and without modifications) and SRIM/TRIM-2008 calculations, the relative differences on total DPA rates of the compound material 90%Fe-56-9%Ni-58-1%Ni-59 are within 1% for two fast spectra, 1.5% for fusion first wall, about 5% for the heavy reflector, and 25% for a pressurized water reactor vessel. (author)