convert_lib80x.py

#!/usr/bin/env python3

"""
Convert ENDF/B-VIII.0 ACE data from LANL into an HDF5 library
that can be used by OpenMC. This assumes that you have a directory containing
subdirectories 'Lib80x' and 'ENDF80SaB'.
"""

import argparse
from collections import defaultdict
from pathlib import Path
import sys

import openmc.data


# Make sure Python version is sufficient
assert sys.version_info >= (3, 6), "Python 3.6+ is required"



class CustomFormatter(argparse.ArgumentDefaultsHelpFormatter,
                      argparse.RawDescriptionHelpFormatter):
    pass


parser = argparse.ArgumentParser(
    description=__doc__,
    formatter_class=CustomFormatter
)
parser.add_argument('-d', '--destination', type=Path, default=Path('lib80x_hdf5'),
                    help='Directory to create new library in')
parser.add_argument('--libver', choices=['earliest', 'latest'],
                    default='earliest', help="Output HDF5 versioning. Use "
                    "'earliest' for backwards compatibility or 'latest' for "
                    "performance")
parser.add_argument('datadir', type=Path,
                    help='Directory containing Lib80x and ENDF80SaB/ENDF80SaB2')

args = parser.parse_args()
assert args.datadir.is_dir()

# Get a list of all ACE files
lib80x = list(args.datadir.glob('Lib80x/**/*.80?nc'))
if (args.datadir / 'ENDF80SaB2').is_dir():
    thermal_dir = args.datadir / 'ENDF80SaB2'
else:
    thermal_dir = args.datadir / 'ENDF80SaB'
lib80sab = list(thermal_dir.glob('**/*.??t'))

# Find and fix B10 ACE files
b10files = list(args.datadir.glob('Lib80x/**/5010.80?nc'))
nxs1_position = 523
for filename in b10files:
    with open(filename, 'r+') as fh:
        # Read NXS(1)
        fh.seek(nxs1_position)
        nxs1 = int(fh.read(5))

        # Increase length to match actual length of XSS, but make sure this
        # isn't done twice by checking the current length
        if nxs1 < 86870:
            fh.seek(nxs1_position)
            fh.write(str(nxs1 + 53))

# Group together tables for the same nuclide
tables = defaultdict(list)
for p in sorted(lib80x + lib80sab):
    tables[p.stem].append(p)

# Create output directory if it doesn't exist
args.destination.mkdir(parents=True, exist_ok=True)

library = openmc.data.DataLibrary()

for name, paths in sorted(tables.items()):
    # Convert first temperature for the table
    p = paths[0]
    print(f'Converting: {p}')
    if p.name.endswith('t'):
        data = openmc.data.ThermalScattering.from_ace(p)
    else:
        data = openmc.data.IncidentNeutron.from_ace(p, 'mcnp')

    # For each higher temperature, add cross sections to the existing table
    for p in paths[1:]:
        print(f'Adding: {p}')
        if p.name.endswith('t'):
            data.add_temperature_from_ace(p)
        else:
            data.add_temperature_from_ace(p, 'mcnp')

    # Export HDF5 file
    h5_file = args.destination / f'{data.name}.h5'
    print(f'Writing {h5_file}...')
    data.export_to_hdf5(h5_file, 'w', libver=args.libver)

    # Register with library
    library.register_file(h5_file)

# Write cross_sections.xml
library.export_to_xml(args.destination / 'cross_sections.xml')