Fusion material transmutation and activation analysis induced by fast neutrons: Anita-IEAF Activation Code Package

This paper presents the Anita-IEAF code package for the activation characterization of materials exposed to neutrons with energies above 20 MeV. Its origins trace back to the Anita-2000 code (NEA-1638, RSICC CCC-606). Anita-IEAF is able to manage the many reaction channels for neutron energies up to 150 MeV. It computes the radioactive inventories of materials exposed to neutron irradiation, continuously or stepwise. It provides activity, isotopic nuclide density, decay heat, biological hazard, clearance index and gamma ray source spectra at shutdown and at different cooling times. The code package is provided with a complete database that includes neutron activation data library, decay, hazard and clearance data library, and gamma library. The Anita-IEAF neutron activation library was produced by processing the IEAF-2001 data activation files that have been recently released by FZK. It contains the neutron activation cross-sections for 679 nuclides in the 256 neutron energy group structure up to 150 MeV, in EAF format. That group structure includes the standard Vitamin-J 175 groups for energies below 20 MeV and 81 groups for the highest energies. The paper presents also an application of the Anita-IEAF code package to the neutron exposure characterization for the SS-316 liner and heat shield of the Test Cell area of the International Fusion Materials Irradiation Facility (IFMIF). The decay gamma source evaluation for SS-316, needed for dose rate calculations at beam-off IFMIF phase for shielding analysis, is discussed too. (authors)