Finding Evaluated Nuclear Data Files

The process of evaluating nuclear reaction data involves combining experimental measurements with theoretical models to come up with a best judgement of the real values of the underlying nuclear reaction data. Some evaluation efforts are devoted to determining a single reaction cross section (e.g., for dosimetry or activation), and others attempt to provide a complete representation of all the cross sections, product yields, and product distributions in energy and angle. The latter are needed for full-scale calculations of the performance of nuclear systems; therefore, they must be in a standard computer-readable format. At the current time, almost all full-scale evaluations use the ENDF (Evaluated Nuclear Data File) format originally developed in the US and now used all over the world (the ENDL format used at Livermore is one exception).

Individual evaluations are normally combined into libraries intended to provide full coverage for nuclear calculations by national or multi-national organizations. These libraries are given a characteristic name with a version identifier for easy reference. Some of the prominent nuclear data libraries available now include

  • ENDF/B-VII -- This is the standard evaluated nuclear reaction library for the US. It is controlled by the Cross Section Evaluation Working Group (CSEWG) of the US Department of Energy and maintained at the National Nuclear Data Center (NNDC) at the Brookhaven National Laboratory. ENDF/B libraries are occasionally updated with "Releases," the latest for ENDF/B-VII being Release 1 (sometimes written as ENDF/B-VII.1).

  • JEFF-3.0 -- This is one version of the standard library for the European Community, and it is administered by the Nuclear Energy Agency (NEA) Data Bank in Paris. JEF has been oriented towards power reactor applications in the past, but it is now being merged with the European Fusion File (EFF) effort to create a new JEFF system that will provide comprehensive data for both fission and fusion systems.

  • JENDL-4 -- This is the standard library for fission applications in Japan. It is controlled by the Japanese Atomic Energy Research Institute (JAEA). The JENDL system includes a separate fusion file, but much of the fusion-oriented data are being merged into the base JENDL library.

  • BROND-2 -- This is an older standard Russian library of evaluated nuclear reaction data, coordinated by the Nuclear Data Center at the Institute of Physics and Power Engineering, Obninsk, Russia.

  • CENDL-2 -- This is the standard Chinese library of evaluated nuclear reaction data, and it is managed by the Chinese Nuclear Data Center at the Institute of Atomic Energy in Beijing, P. R. China.
In addition to these main libraries, each of the evaluated data libraries contains special purpose libraries. Examples of this type of library include the activation file, e.g., ADL-3T from Russia, the ENDF/B-VII.1 decay data from the US, and the ENDF/B charged-particle libraries.

The T-2 Nuclear Information Service provides easy access to these various libraries of evaluated nuclear data through index lists of the materials available for a particular library. The user can browse through the evaluation using interpreted pages in HTML format. Using the index route, you can also get access to the raw ENDF evaluation for viewing or downloading and convenient plots of the data in PDF format.

Using the Index Lists of Evalutions

Currently, the T-2 Nuclear Information Service contains index lists for a number of data libraries, and they are accessible from the Data area. The indexes contain the material identification number (MAT), the nuclide name, and links to additional information, including access to the raw ENDF data, interpreted HTML pages for easy browsing, and PDF plots.

Getting Raw ENDF Data

When you select the raw, or standard, ENDF data, we will see the normal text of an ENDF-format file on your screen. You can easily save this file to your home system using the Save button of your browser (or you can skip the display by using Shift-Select and telling the system where to store the file). This is a convenient way to obtain evaluations for further processing at your home site. Note that we have divided the "tapes" that originally contained a number of materials into single-material files. To obtain the official unmodified distribution tapes, please use the home site for the evaluated library of interest (see above for the links).

Experts can read ENDF-format files easily, because they are used to the structures and the numerical codes (e.g., MAT, MF, MT). Others will have to learn how to read the files by studying the format documentation (PDF), or use the interpreted HTML interface that is provided on this Information Service to browse the files. (The system that provides the interpreted listings also provides quite a bit of help on the ENDF format.)

Browsing Interpreted ENDF Data

When you select interpreted ENDF data, our Web server runs a process to read the raw ENDF file and generate pages in HTML format. The first page gives the basic isotope identification (ZA, AWR, MAT, incident particle), followed by the descriptive information provided for this material (MF=1/MT=451). After the descriptive text, the server provides a set of links to each of the different sections (MF, MT) of data for the material. The code numbers used to define the sections are converted into easily readable text. You just scan through the choices to find the kind of data you want to view (Cross Sections, Angular Distributions), and then select the desired reaction.

Note that there is help information available for some of the types of data---just click on the info symbol.

The pages for a particular data type and reaction typically translate the values for control parameters into labelled values. As an example, you don't have to remember which column contains the Lab/CM flag for an angular distribution; the listing will tell you, "Distributions are in the laboratory system." In some cases, the name for a particular parameter will appear as an underlined link. Just click on such entries for a definition of that parameter. The actual tables of values are normally printed out just as they appear on the raw ENDF file, except column headers are generated to make the tables easier to read. Some things are still pretty cryptic (e.g., interpolation tables), and not all of the help information is present. These things will be improved in the future.
1 May 1998 revised 15 Jan 2011