The EASY-2010 (European Activation System) consists of a wide range of codes, data and documentation all aimed at satisfying the objective of calculating the response of materials irradiated in a neutron flux. The main difference from the previous version is the upper energy limit, which has increased from 20 to 60 MeV. It is designed to investigate both fusion devices and accelerator based materials test facilities that will act as intense sources of high-energy neutrons causing significant activation of the surrounding materials. The very general nature of the calculational method and the data libraries means that it is applicable (with some reservations) to all situations (e.g. fission reactors or neutron sources) where materials are exposed to neutrons below 60 MeV.
EASY can be divided into two parts: data and code development tools and user tools and data. The former are required to develop the latter, but EASY users only need to be able to use the inventory code FISPACT and be aware of the contents of the EAF library (the data source). The complete EASY package contains the FISPACT-2007 inventory code, the EAF-2003, EAF-2005, EAF-2007 and EAF-2010 libraries, and the EASY User Interface for the Window version.
The activation package EASY-2010 is the result of significant development to extend the upper energy range from 20 to 60 MeV so that it is capable of being used for IFMIF calculations. The EAF-2010 library contains 66,256 reactions, almost five times more than in EAF-2003 (12,617).
Deuteron-induced and proton-induced cross section libraries are also included, and can be used with EASY to enable calculations of the activation due to deuterons and proton .
The EAF-2010/2007 data library covers:
Cross section data for neutron-induced reactions
Uncertainty data for neutron-induced reactions
Fission yield data
Biological hazard data
Legal transport data
Charged particle ranges in materials
Emitted particle spectral data (from neutron-induced reactions)
Charged particle cross section data
Gamma absorption data
The EAF-2010/2007 contains the following data libraries:
EAF_XS-2010 is the point-wise cross section library. Data on 66,256 cross sections on 816 targets are held in a modified ENDF/B format. The energy range 10e-5 eV - 60 MeV is covered. All nuclides with a half-life of greater than 0.5 day have cross section data, but in addition some short-lived nuclides are also treated as targets. The cross sections represent targets that are infinitely dilute, no self-shielding is included and the temperature for Doppler broadening is 294K. Reference 2 documents the EAF-2010 cross section library.
EAF_GXS-2010 is a set of multi-group libraries; the available group structures are: WIMS (69), GAM-II (100), XMAS (172), VITAMIN-J (175), VITAMIN-J+ (211), TRIPOLI (315) and TRIPOLI+ (351). Various choices of micro-flux weighting are available for particular applications..
EAF_UN-2010 contains uncertainty data for all cross sections. This library, in modified ENDF/B-6 format, contains error factor values (in 2 to 4 energy groups) for all reactions and is unique amongst activation libraries. This approach to uncertainties is less comprehensive than that found in general purpose evaluated files, but is of great value for fusion related inventory calculations.
EAF_DEC-2010 contains decay data information for 2233 nuclides, it is based primarily on the JEF-3.1.1 radioactive decay data library, with additional data from recent UK evaluations. It includes data on half-lives, decay modes and decay energies. Note that entries are included for all stable nuclides. Care has been taken to ensure that EAF_XS and EAF_DEC are compatible. This is especially important for the identification of isomeric states. All nuclides (including isomeric states) that can be formed from the various reactions in EAF_XS are included so long as their half-lives are greater than 1 second. Some nuclides with shorter half-lives are included where it is felt that they are of particular importance.
EAF_FIS-2007 is taken completely from the JEFF-3.1 fission yield library. It is a library of independent fission yields in ENDF/B-6 format. Only 19 of the 90 nuclides in EAF_XS which have fission cross-sections have any fission yield data in JEFF-3.1 at relevant energies. An inventory code using this data source will need a means of using a neighbouring fission yield for such nuclides.
EAF_HAZ-2007 is a library of values for each radionuclide describing the potential biological impact of that nuclide on human beings. The format is not ENDF/B-6, but is suitable for input by the FISPACT code. The values are Committed Effective Doses per unit uptake, which determine the dose received by a person over their lifetime (50 years) following the ingestion or inhalation of 1 Bq of activity of a particular radionuclide.
EAF_A2-2007 is a library of values relevant for the transport of radionuclides in shielded flasks. The format is not ENDF/B-6, but is suitable for input by the FISPACT code. Transport of radioactive material from place to place is governed by regulations set up by the IAEA. Using these values it is possible to work out how much of a particular mixture of radioactive materials can be packed into a type of container and safely transported. Data from this reference for the nuclides listed are transferred to EAF_A2, with the use of the default prescription given, for all radionuclides not explicitly listed.
EAF_CLEAR-2007 is a library of values relevant for the disposal of radioactive material. The format is not ENDF/B-6, but is suitable for input by the FISPACT code. This contains the clearance limit value for each radionuclide. This value can be used to decide if an amount of a radionuclide can be disposed of with no special precautions.
EAF_STOP-2007 contains new data compared to the previous versions. Due to the change of the upper energy limit from 20 to 60 MeV the data have been recalculated. It is required to enable the effect of sequential charged particle reactions (SCPR) to be investigated.. EAF_STOP contains the differential ranges for protons (p), deuterons (d), helions (h), tritons (t) and alpha particles in all the elements from H to U. The term differential range at a particular energy defines the distance travelled by the particle in the material in losing 1 MeV of energy. Data are given from 0 to 60 MeV.
EAF_SPEC-2007: EAF_XS contains the cross section data for (n,x) reactions, while EAF_SPEC describes the energy distribution of the charged particles emitted in these reactions. This is the second libraries required for SCPR. The data are calculated by a theoretical model code (TALYS) due to the lack of experimental data. Thirty-nine input neutron energies are used and the outgoing charged particles are in 1 MeV bins covering the energy range 0-60 MeV.
EAF_XN-2007 describes the cross sections of p, d, h, t and alpha particles on 775 targets. Ten reactions types are considered: (p,n), (d,n), (h,n), (t,n), (alpha,n), (p,2n), (d,2n), (h,2n), (t,2n) and (alpha,2n). This is the third of the libraries required for SCPR. The data are calculated by a theoretical model code (TALYS) due to the lack of experimental data. The data are given at 1 MeV intervals over the energy range 0-60 MeV.
EAF_ABS contains the photon mass energy attenuation coefficient for all the elements Z= 1 - 100 in increasing Z order. The attenuation coefficient and energy absorption coefficient for air are also listed. All data are stored in a 24 group energy structure.
FISPACT is an inventory code that has been developed for neutron, proton and deuteron-induced activation calculations for materials in fusion devices. FISPACT-2007 uses external libraries of nuclear data for all relevant nuclides to calculate the number of atoms of each species at a specified time during the irradiation or after a decay time following shutdown. The various species are formed either by a direct reaction on a starting material, by a series of reactions some of which can be on radioactive targets or by a decay or series of decays. The accuracy of the calculated inventory is dependent on the quality of the input nuclear data - the cross sections and decay properties - the European Activation File (EAF), described in the next section, is the recommended source of data.
The generation of the European Activation File (EAF) is carried out using the SAFEPAQ-II application that is based on the SYMPAL and SAFEPAQ code systems. SAFEPAQ-II uses as input many world-wide sources of nuclear data. These evaluated files, calculations and experimental data are used to construct a collection of cross section data for neutron-induced reactions on a large set of stable and unstable target nuclides, a decay data file and other data libraries required by FISPACT.
J.A. Simpson and J-Ch Sublet, SYMPAL: Utilities guide, UKAEA FUS 357, 1997
R.A. Forrest and J.A. Simpson, SAFEPAQ: User manual, UKAEA FUS 355, 1997
Regulations for the safe transport of radioactive material, 1985 edition, (and supplement 1988), Safety Series No 6, IAEA, Vienna
S. Cierjacks, P. Oblozinsky and B. Rzehorz, Nuclear data libraries for the treatment of sequential (x,n) reactions in fusion materials activation calculations, KfK 4867, 991
Keywords: cross sections, data.