NJOY21 will be the gold standard of nuclear data processing codes by providing a trusted and verified processing code that is fast, flexible, easy to use and customize, and capable of handling both modern and established nuclear data formats.


The mission of NJOY21 is to build on the experience of previous versions of NJOY while providing a verified and a validated tool to process evaluated nuclear data files that is fast, easy, and convenient.


  1. Maintain NJOY’s image of a trusted and stable processing code

    1. Verified and Validated—Every function and feature is automatically, frequently, and regularly tested
    2. Every feature of NJOY will be documented
    3. Remain backwards compatible with NJOY2016
    4. Provide tools for verification of formats and validation of data
  2. Easier
    • Easier to build NJOY
      • Simple build system for all supported platforms
      • Fully automatic build system—about 5 commands required to build regardless of platform
    • Easier to verify and validate NJOY
      • Platform independent tests
      • Simple execution of tests
    • Easier to interact with NJOY
      • Provide scripting (at least Python) interface to every public component and feature
      • Provide modern interface (scripting an input “deck”)
    • Easier to process nuclear data files
      • Provide accessory tools to assist in the processing and validation of (many) nuclear data files
      • Provide methods to evaluate, process, and test nuclear data formats
  3. Flexible

    • Enable multiple ways of interaction
    • Enable alternative components (i.e., plugins)
  4. Faster
    • Take advantage of modern computer architectures with many CPUs
    • Improve processing algorithms
    • Fast memory management
  5. Maintainable
    • Modularized code
    • Reusable code