NJOY Data Flow

NJOY uses a data-flow model to process evaluated nuclear data. Each module reads some data from one or more input files, transforms it, and writes the results on one or more output files. The order that the modules are used and the particular input and output files used are specified as in the following example:
       [copy an ENDF file onto "tape20"]

       20 21
         ...specific input for RECONR...
       20 21 22
         ...specific input for BROADR...
       20 22 0 23
         ...specific input for GROUPR...
       23 24 22 25
         ...specific input for DTFR...

       [copy tape24 to the DTF library]

In this case, RECONR reads the original ENDF tape and reconstructs the resonances and nonlinear interpolation schemes to prepare a PENDF (pointwise ENDF) tape on unit 21. BROADR reads the PENDF tape, Doppler broadens the pointwise cross sections, and writes a new temperature-dependent PENDF tape on unit 22. Sometimes it needs some data from the ENDF tape, and this is why tape20 is also provided as input. Next, the information from the ENDF and PENDF tapes is run through the multigroup averaging process and written in GENDF format (a special groupwise variation of the ENDF format) on tape23. Finally, the multigroup constants on tape23 are converted to DTF format on tape24. The PENDF input for DTFR is used for the plots, which appear on tape25.

All NJOY jobs are variations of this basic data-flow structure. I/O units with numbers from 20 up can be used to couple the modules together, for the original input files, or for output files. NJOY always names these "tape20", "tape21", and so on. Units from 10 to 19 are used as scratch files. They may be named as tapes, or have special system names. Units with numbers below 10 are used for system input and output files, such as "output".

NJOY is normally run under the control of some kind of system shell. For unix, the NJOY input commands go into the standard input, and runtime messages go out on the standard output. Therefore, if the input "deck" (such as the one outlined above) is named "inx", the following would cause a normal NJOY run to execute:

       njoy < inx

The short listing containing progress messages, notes, and error messages would appear on the screen (or it could be redirected to a file, e.g., outx), and the full listing would appear on a file named "output".

Please don't be shocked at our pleasure in using the terms "tape" and "deck." Later, you will find us talking about input "cards." We do this out of respect for the history of computing, and because we can still remember using tapes and decks of cards!


23 January 2013 T-2 Nuclear Information Service ryxm@lanl.gov