Nuclear Model Calculations of Long-Lived Isomer Production in Neutron Reactions for Fusion Reactor Technology

Intense neutron fluxes within fusion reactors that are currently being designed will lead to the activation of structural components, and to assess and minimize this radioactivity, nuclear cross sections are needed for neutrons with energies up to 20 MeV. We describe research performed for the International Atomic Energy Agency (IAEA) Co-ordinated Research Programme on activation cross sections for fusion reactor technology, which has selected certain high-priority reactions for both experimental and theoretical study. Using statistical model codes, we have investigated excitation function cross sections for radionuclide production in the reactions ⁹⁴Mo(n,p)⁹⁴Nb, ¹⁰⁹Ag(n,2n)^108mAg, ¹⁵¹Eu(n,2n)^150m Eu, ¹⁵³Eu(n,2n)^152g+m2Eu, ¹⁵⁹Tb(n,2n)¹⁵⁸Tb, ¹⁸⁷Re(n,2n)^186mRe, ¹⁷⁹Hf(n,2n)^178m2Hf, ¹⁹³Ir(n,2n)^192m2Ir. Using our calculated results for the excitation functions, along with calculations by other groups, the theoretical excitation functions have been normalized to experimental values at 14.5 MeV to produce evaluated excitation functions. These evaluations can be used within radiation transport and nuclide inventory codes to design, and assess the environmental impact of, fusion reactors.