The European Activation SYstem (EASY) is a complete tool for the calculation of activation in materials exposed to neutrons. It can be used in any application (fusion, transmutation, fission, beam target) where the neutron energy does not exceeds 20 MeV. EASY consists of the inventory code FISPACT and the European Activation File (EAF), which contains various libraries of nuclear data: cross-sections, decay, uncertainty, biological hazard, fission yield, charged particles, gamma attenuation coefficients and transport data for all elements. This paper gives details of the capabilities and contents of the most recent, and significantly upgraded, version: EASY-97.

The processing code SYMPAL is used to perform the necessary data treatment involved in the creation of the cross-section file EAF-97. Data processing encompasses extraction of total or partial cross-sections from evaluated libraries or calculations from nuclear model codes to final assembling in the EAF pointwise format. This includes, amongst many others, tasks such as renormalization of the data, splitting into isomeric channels and correction of the excitation function shape in given energy ranges. The processing code assembles the new data library from two databases: the Master Parameter File (MPF) and the Master Data File (MDF). The MPF contains all physical information and the experimental or systematic data. The MDF contains the original data extracted from different sources: JEF, EFF, ADL, ENDF/B, JENDL, IRK, FEI, JAERI etc. SYMPAL combines the two databases together, producing a distribution file in a pointwise format. The EAF-97 library contains about 12500 excitation functions involving 766 different targets from 1H to 257Fm, atomic numbers 1 to 100, in the energy range 10-5 eV to 20 MeV. Internal validation procedures, against either experimental data (compilation and EXFOR) or systematics, enables a comprehensive assessment of the data. Automatically, in SYMPAL, 3085 reactions and branching ratios are normalised to either experimental or systematic data, about 25% of all reactions. The pointwise file is then processed in seven special purpose groupwise libraries with different micro flux weighting spectrum to fit various users needs. Uniquely, an uncertainty file is also provided that quantifies the degree of confidence placed on each reaction cross-section.

A high level of consistency between the various libraries has been achieved. Half-life uncertainty information has been added to the new decay library (1917 isotopes) when it was missing, as is the case even for major evaluated libaries. The FISPACT-97 code has also been improved. The most important of the new facilities is the ability to calculate uncertainty in a radiological quantity due to uncertainty in both the cross-section and the half-life. Better algorithms and gamma absorption data are now used to calculate the gamma dose. New input codewords have been created to handle more efficiently pulsed operation and burnup related calculations.

*This work was jointly funded by the UK Department of Trade and Industry and Euratom