The European Activation File: EAF-2005 cross section library
In the European fusion programme, safety and environmental issues are of great importance in the continuing development of power plants. In support of this programme, a sound, complete and reliable neutron-induced cross section data library is required. The European Activation File (EAF) project has been an ongoing process performed through European and world-wide co-operation that has led to the creation of succeeding EAF versions. The latest release, EAF-2005, in a significant change from previous versions has an upper energy limit of 60 rather than 20 MeV. EAF- 2005 has benefited from the generation and maintenance of comprehensive activation files and the development of the processing code SAFEPAQ-II. Cross section validation exercises against both experimental data and systematics, which were started on the EAF-4 file, enable a comprehensive assessment of the data. SAFEPAQII is used to apply a series of modifications to the original source data. A very important set of modifications concerns renormalisation and branching using experimental or systematic data. A total of 7,268 reactions have been so changed; 12% of all the reactions. These are challenging tasks when the source contains nonthreshold reactions with an energy dependent branching ratio. Although EAF-2005 is the best-validated cross section library in the world, currently less than 3% of all the reactions can be compared with experimental information, and sometimes then only for very limited, and not always fusion relevant, energy ranges. As with EAF-2001 and -2003, results of integral experiments have been used to correct, adjust and validate data. This can be done using SAFEPAQ-II by inputting the measured effective cross sections. Validation using integral data has been performed by means of direct comparison with measurements of various materials under fusion-relevant neutron spectra. Irradiations have been carried out at ENEA FNG, FZK Isochron-cyclotron, Sergiev Posad SNEG-13, TUD, Rez. and JAERI FNS and integral C/E comparisons made (C/E is the ratio of the library to the experimental value). The results of these benchmarking exercises have indicated, in conjunction with differential data, where modifications to the data can be applied. The EAF-2005 library contains 62,637 excitation functions involving 775 different targets from 1H to 257Fm, atomic numbers 1 to 100, in the energy range 10-5 eV to 60 MeV. The 3,472,000 lines that make up the point-wise file are then processed into numerous group-wise files with different micro-flux weighting spectra to meet various user needs. Uniquely, an uncertainty file is also provided that quantifies the degree of confidence placed on the data for each reaction channel.