Development of a Novel Algorithm and Production of New Nuclear Data Libraries for the Treatment of Sequential (x,n) Reactions in Fusion Material Activation Calculations

A new algorithm and three major nuclear data libraries were developed for the kinematically complete treatment of sequential (x,n) reactions infusion material activation calculations. The new libraries include data for virtually all isotopes with Z≤ 84 (A ≤ 210) and half-lives exceeding 1 day; primary neutron energies E_n < 20 MeV; and secondary charged particles x = p, d, t, ³He, and α with energies E_x < 24 MeV. While production cross sections of charged particles for primary (n,x) reactions can be deduced from the European activation file, the KFKSPEC data file was created for the corresponding normalized charged-particle spectra. The second data file, KFKXN, contains cross sections for secondary (x,n) reactions. The third data file, KFKSTOP, has a complete set of differential ranges for all five aforementioned light charged particles and all elements from hydrogen to uranium. The KFKSPEC and KFKXN libraries are based essentially on nuclear model calculations using the statistical evaporation model superimposed with the pre-equilibrium contribution as implemented in the Lawrence Livermore National Laboratory ALICE code. The KFKSPEC library includes 633 isotopes, of which 55 are in their isomeric states, and contains 63 300 spectra of the (n,x) type with almost 1.5 million data points. The KFKXN library also includes 633 isotopes and contains all (x,n) and partly (x,2n) cross sections for 4431 reactions with ∼106 000 data points. The KFKSTOP library is considered complete and has 11040 data points.