groupy

package to parse GENDF files, which are the output of the NJOY GROUPR module.

dependencies

The LANL program NJOY must be installed, and the executable should be available on the path. Running NJOY with groupy has currently only been tested on Ubuntu 22.04.

This package requires that the LANL program ENDFtk is installed and added to the python path.

installation

Move into the groupy directory and run

pip install .

using the groupy package

The main function is the get_grouped_data function.

from groupy import get_grouped_data

obj = get_grouped_data("<endf6-file>", title)

get_grouped_data has many optional parameters to customize the NJOY input.

    Parameters
    ----------
    endf6_file : str or pathlib.Path object
        the ENDF6-formatted file

    title : str
        the run title

    directory : str, optional, default is '.'
        the directory in which to run NJOY. Default is the current
        directory.

    temperature : float, optional, default is 293 K
        the temperature of the run in K

    reconr_tolerance : float, optional, default is 0.001
        the tolerance for the reconr module

    broadr_tolerance : float, optional, default is 0.001
        the tolerance for the broader module

    group_boundaries : int or list
        The group boundaries to use. If an integer, it represents ign in the
        NJOY input. If a list, it is the energy boundaries in eV.

    flux : int
        The weighting flux to use - the iwt value in the NJOY input. Currently
        the only iwt values allowed are:
            2   constant
            3   1/e
            5   epri-cell lwr
            9   claw weight function
            11  vitamin-e weight function


    legendre_order : int, optional, default is 1
        the order to reconstruct the angular distributions


    verbose : bool, optional, default is False
        If true, extra information will be printed to the screen

Running NJOY

NJOY can be run individually with the run_njoy function.

from groupy import run_njoy

run_njoy("<endf6-file>", title)

run_njoy has many optional parameters to customize the NJOY input.

    Parameters
    ----------
    endf6_file : str or pathlib.Path object
        the ENDF6-formatted file

    title : str
        the run title

    directory : str, optional, default is '.'
        the directory in which to run NJOY. Default is the current
        directory.

    temperature : float, optional, default is 293 K
        the temperature of the run in K

    reconr_tolerance : float, optional, default is 0.001
        the tolerance for the reconr module

    broadr_tolerance : float, optional, default is 0.001
        the tolerance for the broader module

    group_boundaries : int or list
        The group boundaries to use. If an integer, it represents ign in the
        NJOY input. If a list, it is the energy boundaries in eV.

    flux : int, optional, default is 5
        The weighting flux to use - the iwt value in the NJOY input. Currently
        the only iwt values allowed are:
            2   constant
            3   1/e
            5   epri-cell lwr
            9   claw weight function
            11  vitamin-e weight function

    legendre_order : int, optional, default is 1
        the order to reconstruct the angular distributions

    verbose : bool, optional, default is False
        If true, extra information will be printed to the screen

The group boundary and flux options are explained in detail in the NJOY Manual.

The GROUPR output is put into a file named tape91.

Parsing a GENDF file

The output of the GROUPR module is a GENDF-formatted file. The GrouprOutput class can currently parse the energy boundaries (MF1), pointwise values (MF3), outgoing energy distributions (MF5) and scattering matrices (MF6) from the GENDF-formatted file.

from groupy import GrouprOutput

obj = GrouprOutput(<gendf-file>)

The energy group boundaries, in eV, are in obj.energy_boundaries.

The pointwise values are in the dictionary obj.pointwise, which has MT values for keys and PointwiseValues objects as values. The values can be accessed with obj.pointwise[mt].values.

Outgoing energy distributions are in the dictionary obj.outgoing_distributions, and the scattering matrices are in the dictionary obj.scattering_matrices. The values are accessed and plotted in an example file.

The values can be written out to CSV files with the obj.write_to_csv() function.

Command Line Interface

There is a command line interface to the get_grouped_data function with limited options. It can be called with

group <endf6-file>

The optional flags are:

usage: group [-h] [--temp TEMP] [--groups GROUPS] [--flux {2,3,5,9,11}] [-v] endf_file

positional arguments:
  endf_file            Path to ENDF6-formatted file

options:
  -h, --help           show this help message and exit
  --temp TEMP          Temperature in K
  --groups GROUPS      Grouping option
  --flux {2,3,5,9,11}  Weighting flux option
  -v                   Verbose mode

The CLI does not allow for a list of group boundaries, only the integer grouping options. It also does not allow for the default tolerance values or legendre order to be changed, and automatically creates the title "groupedAAAXX"