Updating of the Libraries Included in the ANITA-2000 Code Package on the Basis of the JEFF-3.1.1 Radioactive Decay Data Library

ANITA-2000 is a code package for the activation characterization of materials exposed to neutron irradiation released by ENEA at OECD-NEADB (NEA-1638). The package contains: a) the activation code ANITA-4M, based on the original code developed at CEC JRC Ispra, able to compute the radioactive inventory of a material exposed to neutron irradiation, continuous or stepwise, b) two activation cross section libraries, c) the decay data library (file “fl1”) containing the quantities describing the decay properties of unstable nuclides and d) the library (file “fl2”) containing the gamma ray spectra emitted by the radioactive nuclei in the ORNL-SCALE 18- energy group structure. The data contained in the “fl1” and “fl2” libraries of the ANITA-2000 code package are based on the evaluated data library FENDL/D-2.0. Taking into account a specific interest of ENEA and Ansaldo Nucleare, the ANITA-2000 “fl1” and “fl2” libraries were updated on the basis of the JEFF-3.1.1 Radioactive Decay Data Library. This work required the setting up of a series of proper interface codes in order to process and convert the JEFF-3.1.1 evaluated decay data (in ENDF-6 standard format) into the format required by ANITA-4M code. A preliminary validation of the new libraries has been performed through the comparison of the ANITA-4M calculations against measurements of electron-photon decay heat and activity of neutron activated materials from FNG (Frascati Neutron Generator) experiment.