def test_element_wo():
# This test doesn't require an OpenMC run. We just need to make sure the
# element.expand() method expands elements with the proper nuclide
# compositions.
h_am = (NATURAL_ABUNDANCE['H1'] * atomic_mass('H1') +
NATURAL_ABUNDANCE['H2'] * atomic_mass('H2'))
o_am = (NATURAL_ABUNDANCE['O17'] * atomic_mass('O17') +
(NATURAL_ABUNDANCE['O16'] + NATURAL_ABUNDANCE['O18'])
* atomic_mass('O16'))
water_am = 2 * h_am + o_am
water = Material()
water.add_element('O', o_am / water_am, 'wo')
water.add_element('H', 2 * h_am / water_am, 'wo')
densities = water.get_nuclide_densities()
for nuc in densities.keys():
assert nuc in ('H1', 'H2', 'O16', 'O17')
if nuc in ('H1', 'H2'):
val = 2 * NATURAL_ABUNDANCE[nuc] * atomic_mass(nuc) / water_am
assert densities[nuc][1] == pytest.approx(val)
if nuc == 'O16':
val = (NATURAL_ABUNDANCE[nuc] + NATURAL_ABUNDANCE['O18']) \
* atomic_mass(nuc) / water_am
assert densities[nuc][1] == pytest.approx(val)
if nuc == 'O17':
val = NATURAL_ABUNDANCE[nuc] * atomic_mass(nuc) / water_am
assert densities[nuc][1] == pytest.approx(val)
def test_atoms_material_cell(uo2, water):
""" Test if correct number of atoms is returned.
Also check if Cell.atoms still works after volume/material was changed
"""
c = openmc.Cell(fill=uo2)
c.volume = 2.0
expected_nucs = ['U235', 'O16']
# Precalculate the expected number of atoms
M = (atomic_mass('U235') + 2 * atomic_mass('O16')) / 3
expected_atoms = [
1 / 3 * uo2.density / M * AVOGADRO * 2.0, # U235
2 / 3 * uo2.density / M * AVOGADRO * 2.0 # O16
]
tuples = c.atoms.items()
for nuc, atom_num, t in zip(expected_nucs, expected_atoms, tuples):
assert nuc == t[0]
assert atom_num == pytest.approx(t[1])
# Change volume and check if OK
c.volume = 3.0
expected_atoms = [
1 / 3 * uo2.density / M * AVOGADRO * 3.0, # U235
2 / 3 * uo2.density / M * AVOGADRO * 3.0 # O16
]
tuples = c.atoms.items()
for nuc, atom_num, t in zip(expected_nucs, expected_atoms, tuples):
assert nuc == t[0]
assert atom_num == pytest.approx(t[1])
# Change material and check if OK
c.fill = water
expected_nucs = ['H1', 'O16']
M = (2 * atomic_mass('H1') + atomic_mass('O16')) / 3
expected_atoms = [
2 / 3 * water.density / M * AVOGADRO * 3.0, # H1
1 / 3 * water.density / M * AVOGADRO * 3.0 # O16
]
tuples = c.atoms.items()
for nuc, atom_num, t in zip(expected_nucs, expected_atoms, tuples):
assert nuc == t[0]
assert atom_num == pytest.approx(t[1])
def test_element_wo():
# This test doesn't require an OpenMC run. We just need to make sure the
# element.expand() method expands elements with the proper nuclide
# compositions.
h_am = (NATURAL_ABUNDANCE['H1'] * atomic_mass('H1') +
NATURAL_ABUNDANCE['H2'] * atomic_mass('H2'))
o_am = (NATURAL_ABUNDANCE['O17'] * atomic_mass('O17') +
(NATURAL_ABUNDANCE['O16'] + NATURAL_ABUNDANCE['O18'])
* atomic_mass('O16'))
water_am = 2 * h_am + o_am
water = Material()
water.add_element('O', o_am / water_am, 'wo')
water.add_element('H', 2 * h_am / water_am, 'wo')
densities = water.get_nuclide_densities()
for nuc in densities.keys():
assert nuc in ('H1', 'H2', 'O16', 'O17')
if nuc in ('H1', 'H2'):
val = 2 * NATURAL_ABUNDANCE[nuc] * atomic_mass(nuc) / water_am
assert densities[nuc][1] == pytest.approx(val)
if nuc == 'O16':
val = (NATURAL_ABUNDANCE[nuc] + NATURAL_ABUNDANCE['O18']) \
* atomic_mass(nuc) / water_am
assert densities[nuc][1] == pytest.approx(val)
if nuc == 'O17':
val = NATURAL_ABUNDANCE[nuc] * atomic_mass(nuc) / water_am
assert densities[nuc][1] == pytest.approx(val)
def test_expand_no_enrichment():
""" Expand Li in natural compositions"""
lithium = openmc.Element('Li')
# Verify the expansion into ATOMIC fraction against natural composition
for isotope in lithium.expand(100.0, 'ao'):
assert isotope[1] == approx(NATURAL_ABUNDANCE[isotope[0]] * 100.0)
# Verify the expansion into WEIGHT fraction against natural composition
natural = {
'Li6': NATURAL_ABUNDANCE['Li6'] * atomic_mass('Li6'),
'Li7': NATURAL_ABUNDANCE['Li7'] * atomic_mass('Li7')
}
li_am = sum(natural.values())
for key in natural:
natural[key] /= li_am
for isotope in lithium.expand(100.0, 'wo'):
assert isotope[1] == approx(natural[isotope[0]] * 100.0)
def test_atoms_distribmat_cell(uo2, water):
""" Test if correct number of atoms is returned for a cell with
'distribmat' fill
"""
c = openmc.Cell(fill=[uo2, water])
c.volume = 6.0
# Calculate the expected number of atoms
expected_nucs = ['U235', 'O16', 'H1']
M_uo2 = (atomic_mass('U235') + 2 * atomic_mass('O16')) / 3
M_water = (2 * atomic_mass('H1') + atomic_mass('O16')) / 3
expected_atoms = [
1 / 3 * uo2.density / M_uo2 * AVOGADRO * 3.0, # U235
(2 / 3 * uo2.density / M_uo2 * AVOGADRO * 3.0 +
1 / 3 * water.density / M_water * AVOGADRO * 3.0), # O16
2 / 3 * water.density / M_water * AVOGADRO * 3.0 # H1
]
tuples = c.atoms.items()
for nuc, atom_num, t in zip(expected_nucs, expected_atoms, tuples):
assert nuc == t[0]
assert atom_num == pytest.approx(t[1])
def expand(self,
percent,
percent_type,
enrichment=None,
enrichment_target=None,
enrichment_type=None,
cross_sections=None):
"""Expand natural element into its naturally-occurring isotopes.
An optional cross_sections argument or the :envvar:`OPENMC_CROSS_SECTIONS`
environment variable is used to specify a cross_sections.xml file.
If the cross_sections.xml file is found, the element is expanded only
into the isotopes/nuclides present in cross_sections.xml. If no
cross_sections.xml file is found, the element is expanded based on its
naturally occurring isotopes.
Parameters
----------
percent : float
Atom or weight percent
percent_type : {'ao', 'wo'}
'ao' for atom percent and 'wo' for weight percent
enrichment : float, optional
Enrichment of an enrichment_taget nuclide in percent (ao or wo).
If enrichment_taget is not supplied then it is enrichment for U235
in weight percent. For example, input 4.95 for 4.95 weight percent
enriched U. Default is None (natural composition).
enrichment_target: str, optional
Single nuclide name to enrich from a natural composition (e.g., 'O16')
.. versionadded:: 0.12
enrichment_type: {'ao', 'wo'}, optional
'ao' for enrichment as atom percent and 'wo' for weight percent.
Default is: 'ao' for two-isotope enrichment; 'wo' for U enrichment
.. versionadded:: 0.12
cross_sections : str, optional
Location of cross_sections.xml file. Default is None.
Returns
-------
isotopes : list
Naturally-occurring isotopes of the element. Each item of the list
is a tuple consisting of a nuclide string, the atom/weight percent,
and the string 'ao' or 'wo'.
Raises
------
ValueError
No data is available for any of natural isotopes of the element
ValueError
If only some natural isotopes are available in the cross-section data
library and the element is not O, W, or Ta
ValueError
If a non-naturally-occurring isotope is requested
ValueError
If enrichment is requested of an element with more than two
naturally-occurring isotopes.
ValueError
If enrichment procedure for Uranium is used when element is not
Uranium.
ValueError
Uranium enrichment is requested with enrichment_type=='ao'
Notes
-----
When the `enrichment` argument is specified, a correlation from
`ORNL/CSD/TM-244 <https://doi.org/10.2172/5561567>`_ is used to
calculate the weight fractions of U234, U235, U236, and U238. Namely,
the weight fraction of U234 and U236 are taken to be 0.89% and 0.46%,
respectively, of the U235 weight fraction. The remainder of the
isotopic weight is assigned to U238.
When the `enrichment` argument is specified with `enrichment_target`, a
general enrichment procedure is used for elements composed of exactly
two naturally-occurring isotopes. `enrichment` is interpreted as atom
percent by default but can be controlled by the `enrichment_type`
argument.
"""
# Check input
if enrichment_type is not None:
cv.check_value('enrichment_type', enrichment_type, {'ao', 'wo'})
if enrichment is not None:
cv.check_less_than('enrichment', enrichment, 100.0, equality=True)
cv.check_greater_than('enrichment', enrichment, 0., equality=True)
# Get the nuclides present in nature
natural_nuclides = {name for name, abundance in natural_isotopes(self)}
# Create dict to store the expanded nuclides and abundances
abundances = OrderedDict()
# If cross_sections is None, get the cross sections from the
# OPENMC_CROSS_SECTIONS environment variable
if cross_sections is None:
cross_sections = os.environ.get('OPENMC_CROSS_SECTIONS')
# If a cross_sections library is present, check natural nuclides
# against the nuclides in the library
if cross_sections is not None:
library_nuclides = set()
tree = ET.parse(cross_sections)
root = tree.getroot()
for child in root.findall('library'):
nuclide = child.attrib['materials']
if re.match(r'{}\d+'.format(self), nuclide) and \
'_m' not in nuclide:
library_nuclides.add(nuclide)
# Get a set of the mutual and absent nuclides. Convert to lists
# and sort to avoid different ordering between Python 2 and 3.
mutual_nuclides = natural_nuclides.intersection(library_nuclides)
absent_nuclides = natural_nuclides.difference(mutual_nuclides)
mutual_nuclides = sorted(list(mutual_nuclides))
absent_nuclides = sorted(list(absent_nuclides))
# If all natural nuclides are present in the library,
# expand element using all natural nuclides
if len(absent_nuclides) == 0:
for nuclide in mutual_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# If no natural elements are present in the library, check if the
# 0 nuclide is present. If so, set the abundance to 1 for this
# nuclide. Else, raise an error.
elif len(mutual_nuclides) == 0:
nuclide_0 = self + '0'
if nuclide_0 in library_nuclides:
abundances[nuclide_0] = 1.0
else:
msg = 'Unable to expand element {0} because the cross '\
'section library provided does not contain any of '\
'the natural isotopes for that element.'\
.format(self)
raise ValueError(msg)
# If some, but not all, natural nuclides are in the library, add
# the mutual nuclides. For the absent nuclides, add them based on
# our knowledge of the common cross section libraries
# (ENDF, JEFF, and JENDL)
else:
# Add the mutual isotopes
for nuclide in mutual_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# Adjust the abundances for the absent nuclides
for nuclide in absent_nuclides:
if nuclide in ['O17', 'O18'] and 'O16' in mutual_nuclides:
abundances['O16'] += NATURAL_ABUNDANCE[nuclide]
elif nuclide == 'Ta180' and 'Ta181' in mutual_nuclides:
abundances['Ta181'] += NATURAL_ABUNDANCE[nuclide]
elif nuclide == 'W180' and 'W182' in mutual_nuclides:
abundances['W182'] += NATURAL_ABUNDANCE[nuclide]
else:
msg = 'Unsure how to partition natural abundance of ' \
'isotope {0} into other natural isotopes of ' \
'this element that are present in the cross ' \
'section library provided. Consider adding ' \
'the isotopes of this element individually.'
raise ValueError(msg)
# If a cross_section library is not present, expand the element into
# its natural nuclides
else:
for nuclide in natural_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# Modify mole fractions if enrichment provided
# Old treatment for Uranium
if enrichment is not None and enrichment_target is None:
# Check that the element is Uranium
if self.name != 'U':
msg = ('Enrichment procedure for Uranium was requested, '
'but the isotope is {} not U'.format(self))
raise ValueError(msg)
# Check that enrichment_type is not 'ao'
if enrichment_type == 'ao':
msg = ('Enrichment procedure for Uranium requires that '
'enrichment value is provided as wo%.')
raise ValueError(msg)
# Calculate the mass fractions of isotopes
abundances['U234'] = 0.0089 * enrichment
abundances['U235'] = enrichment
abundances['U236'] = 0.0046 * enrichment
abundances['U238'] = 100.0 - 1.0135 * enrichment
# Convert the mass fractions to mole fractions
for nuclide in abundances.keys():
abundances[nuclide] /= atomic_mass(nuclide)
# Normalize the mole fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Modify mole fractions if enrichment provided
# New treatment for arbitrary element
elif enrichment is not None and enrichment_target is not None:
# Provide more informative error message for U235
if enrichment_target == 'U235':
msg = ("There is a special procedure for enrichment of U235 "
"in U. To invoke it, the arguments 'enrichment_target'"
"and 'enrichment_type' should be omitted. Provide "
"a value only for 'enrichment' in weight percent.")
raise ValueError(msg)
# Check if it is two-isotope mixture
if len(abundances) != 2:
msg = (
'Element {} does not consist of two naturally-occurring '
'isotopes. Please enter isotopic abundances manually.'.
format(self))
raise ValueError(msg)
# Check if the target nuclide is present in the mixture
if enrichment_target not in abundances:
msg = (
'The target nuclide {} is not one of the naturally-occurring '
'isotopes ({})'.format(enrichment_target,
list(abundances)))
raise ValueError(msg)
# If weight percent enrichment is requested convert to mass fractions
if enrichment_type == 'wo':
# Convert the atomic abundances to weight fractions
# Compute the element atomic mass
element_am = sum(
atomic_mass(nuc) * abundances[nuc] for nuc in abundances)
# Convert Molar Fractions to mass fractions
for nuclide in abundances:
abundances[nuclide] *= atomic_mass(nuclide) / element_am
# Normalize to one
sum_abundances = sum(abundances.values())
for nuclide in abundances:
abundances[nuclide] /= sum_abundances
# Enrich the mixture
# The procedure is more generic that it needs to be. It allows
# to enrich mixtures of more then 2 isotopes, keeping the ratios
# of non-enriched nuclides the same as in natural composition
# Get fraction of non-enriched isotopes in nat. composition
non_enriched = 1.0 - abundances[enrichment_target]
tail_fraction = 1.0 - enrichment / 100.0
# Enrich all nuclides
# Do bogus operation for enrichment target but overwrite immediatly
# to avoid if statement in the loop
for nuclide, fraction in abundances.items():
abundances[nuclide] = tail_fraction * fraction / non_enriched
abundances[enrichment_target] = enrichment / 100.0
# Convert back to atomic fractions if requested
if enrichment_type == 'wo':
# Convert the mass fractions to mole fractions
for nuclide in abundances:
abundances[nuclide] /= atomic_mass(nuclide)
# Normalize the mole fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances:
abundances[nuclide] /= sum_abundances
# Compute the ratio of the nuclide atomic masses to the element
# atomic mass
if percent_type == 'wo':
# Compute the element atomic mass
element_am = 0.
for nuclide in abundances.keys():
element_am += atomic_mass(nuclide) * abundances[nuclide]
# Convert the molar fractions to mass fractions
for nuclide in abundances.keys():
abundances[nuclide] *= atomic_mass(nuclide) / element_am
# Normalize the mass fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Create a list of the isotopes in this element
isotopes = []
for nuclide, abundance in abundances.items():
isotopes.append((nuclide, percent * abundance, percent_type))
return isotopes
import os
import sys
import numpy as np
sys.path.insert(0, os.pardir)
sys.path.insert(0, os.path.join(os.pardir, os.pardir))
from openmc import Material
from openmc.data import NATURAL_ABUNDANCE, atomic_mass
if __name__ == '__main__':
# This test doesn't require an OpenMC run. We just need to make sure the
# element.expand() method expands elements with the proper nuclide
# compositions.
h_am = (NATURAL_ABUNDANCE['H1'] * atomic_mass('H1') +
NATURAL_ABUNDANCE['H2'] * atomic_mass('H2'))
o_am = (NATURAL_ABUNDANCE['O17'] * atomic_mass('O17') +
(NATURAL_ABUNDANCE['O16'] + NATURAL_ABUNDANCE['O18']) *
atomic_mass('O16'))
water_am = 2 * h_am + o_am
water = Material()
water.add_element('O', o_am / water_am, 'wo')
water.add_element('H', 2 * h_am / water_am, 'wo')
densities = water.get_nuclide_densities()
for nuc in densities.keys():
assert nuc in ('H1', 'H2', 'O16', 'O17')
if nuc in ('H1', 'H2'):
def expand(self,
percent,
percent_type,
enrichment=None,
cross_sections=None):
"""Expand natural element into its naturally-occurring isotopes.
An optional cross_sections argument or the OPENMC_CROSS_SECTIONS
environment variable is used to specify a cross_sections.xml file.
If the cross_sections.xml file is found, the element is expanded only
into the isotopes/nuclides present in cross_sections.xml. If no
cross_sections.xml file is found, the element is expanded based on its
naturally occurring isotopes.
Parameters
----------
percent : float
Atom or weight percent
percent_type : {'ao', 'wo'}
'ao' for atom percent and 'wo' for weight percent
enrichment : float, optional
Enrichment for U235 in weight percent. For example, input 4.95 for
4.95 weight percent enriched U. Default is None
(natural composition).
cross_sections : str, optional
Location of cross_sections.xml file. Default is None.
Returns
-------
isotopes : list
Naturally-occurring isotopes of the element. Each item of the list
is a tuple consisting of an openmc.Nuclide instance and the natural
abundance of the isotope.
"""
# Get the nuclides present in nature
natural_nuclides = set()
for nuclide in sorted(NATURAL_ABUNDANCE.keys()):
if re.match(r'{}\d+'.format(self.name), nuclide):
natural_nuclides.add(nuclide)
# Create dict to store the expanded nuclides and abundances
abundances = OrderedDict()
# If cross_sections is None, get the cross sections from the
# OPENMC_CROSS_SECTIONS environment variable
if cross_sections is None:
cross_sections = os.environ.get('OPENMC_CROSS_SECTIONS')
# If a cross_sections library is present, check natural nuclides
# against the nuclides in the library
if cross_sections is not None:
library_nuclides = set()
tree = ET.parse(cross_sections)
root = tree.getroot()
for child in root:
nuclide = child.attrib['materials']
if re.match(r'{}\d+'.format(self.name), nuclide) and \
'_m' not in nuclide:
library_nuclides.add(nuclide)
# Get a set of the mutual and absent nuclides. Convert to lists
# and sort to avoid different ordering between Python 2 and 3.
mutual_nuclides = natural_nuclides.intersection(library_nuclides)
absent_nuclides = natural_nuclides.difference(mutual_nuclides)
mutual_nuclides = sorted(list(mutual_nuclides))
absent_nuclides = sorted(list(absent_nuclides))
# If all natural nuclides are present in the library, expand element
# using all natural nuclides
if len(absent_nuclides) == 0:
for nuclide in mutual_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# If no natural elements are present in the library, check if the
# 0 nuclide is present. If so, set the abundance to 1 for this
# nuclide. Else, raise an error.
elif len(mutual_nuclides) == 0:
nuclide_0 = self.name + '0'
if nuclide_0 in library_nuclides:
abundances[nuclide_0] = 1.0
else:
msg = 'Unable to expand element {0} because the cross '\
'section library provided does not contain any of '\
'the natural isotopes for that element.'\
.format(self.name)
raise ValueError(msg)
# If some, but not all, natural nuclides are in the library, add
# the mutual nuclides. For the absent nuclides, add them based on
# our knowledge of the common cross section libraries
# (ENDF, JEFF, and JENDL)
else:
# Add the mutual isotopes
for nuclide in mutual_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# Adjust the abundances for the absent nuclides
for nuclide in absent_nuclides:
if nuclide in ['O17', 'O18'] and 'O16' in mutual_nuclides:
abundances['O16'] += NATURAL_ABUNDANCE[nuclide]
elif nuclide == 'Ta180' and 'Ta181' in mutual_nuclides:
abundances['Ta181'] += NATURAL_ABUNDANCE[nuclide]
elif nuclide == 'W180' and 'W182' in mutual_nuclides:
abundances['W182'] += NATURAL_ABUNDANCE[nuclide]
else:
msg = 'Unsure how to partition natural abundance of ' \
'isotope {0} into other natural isotopes of ' \
'this element that are present in the cross ' \
'section library provided. Consider adding ' \
'the isotopes of this element individually.'
raise ValueError(msg)
# If a cross_section library is not present, expand the element into
# its natural nuclides
else:
for nuclide in natural_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# Modify mole fractions if enrichment provided
if enrichment is not None:
# Calculate the mass fractions of isotopes
abundances['U234'] = 0.008 * enrichment
abundances['U235'] = enrichment
abundances['U238'] = 100.0 - 1.008 * enrichment
# Convert the mass fractions to mole fractions
for nuclide in abundances.keys():
abundances[nuclide] /= atomic_mass(nuclide)
# Normalize the mole fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Compute the ratio of the nuclide atomic masses to the element
# atomic mass
if percent_type == 'wo':
# Compute the element atomic mass
element_am = 0.
for nuclide in abundances.keys():
element_am += atomic_mass(nuclide) * abundances[nuclide]
# Convert the molar fractions to mass fractions
for nuclide in abundances.keys():
abundances[nuclide] *= atomic_mass(nuclide) / element_am
# Normalize the mass fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Create a list of the isotopes in this element
isotopes = []
for nuclide, abundance in abundances.items():
nuc = openmc.Nuclide(nuclide)
nuc.scattering = self.scattering
isotopes.append((nuc, percent * abundance, percent_type))
return isotopes
def expand(self, percent, percent_type, enrichment=None,
cross_sections=None):
"""Expand natural element into its naturally-occurring isotopes.
An optional cross_sections argument or the OPENMC_CROSS_SECTIONS
environment variable is used to specify a cross_sections.xml file.
If the cross_sections.xml file is found, the element is expanded only
into the isotopes/nuclides present in cross_sections.xml. If no
cross_sections.xml file is found, the element is expanded based on its
naturally occurring isotopes.
Parameters
----------
percent : float
Atom or weight percent
percent_type : {'ao', 'wo'}
'ao' for atom percent and 'wo' for weight percent
enrichment : float, optional
Enrichment for U235 in weight percent. For example, input 4.95 for
4.95 weight percent enriched U. Default is None
(natural composition).
cross_sections : str, optional
Location of cross_sections.xml file. Default is None.
Returns
-------
isotopes : list
Naturally-occurring isotopes of the element. Each item of the list
is a tuple consisting of an openmc.Nuclide instance and the natural
abundance of the isotope.
"""
# Get the nuclides present in nature
natural_nuclides = set()
for nuclide in sorted(NATURAL_ABUNDANCE.keys()):
if re.match(r'{}\d+'.format(self.name), nuclide):
natural_nuclides.add(nuclide)
# Create dict to store the expanded nuclides and abundances
abundances = OrderedDict()
# If cross_sections is None, get the cross sections from the
# OPENMC_CROSS_SECTIONS environment variable
if cross_sections is None:
cross_sections = os.environ.get('OPENMC_CROSS_SECTIONS')
# If a cross_sections library is present, check natural nuclides
# against the nuclides in the library
if cross_sections is not None:
library_nuclides = set()
tree = ET.parse(cross_sections)
root = tree.getroot()
for child in root:
nuclide = child.attrib['materials']
if re.match(r'{}\d+'.format(self.name), nuclide) and \
'_m' not in nuclide:
library_nuclides.add(nuclide)
# Get a set of the mutual and absent nuclides. Convert to lists
# and sort to avoid different ordering between Python 2 and 3.
mutual_nuclides = natural_nuclides.intersection(library_nuclides)
absent_nuclides = natural_nuclides.difference(mutual_nuclides)
mutual_nuclides = sorted(list(mutual_nuclides))
absent_nuclides = sorted(list(absent_nuclides))
# If all natural nuclides are present in the library, expand element
# using all natural nuclides
if len(absent_nuclides) == 0:
for nuclide in mutual_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# If no natural elements are present in the library, check if the
# 0 nuclide is present. If so, set the abundance to 1 for this
# nuclide. Else, raise an error.
elif len(mutual_nuclides) == 0:
nuclide_0 = self.name + '0'
if nuclide_0 in library_nuclides:
abundances[nuclide_0] = 1.0
else:
msg = 'Unable to expand element {0} because the cross '\
'section library provided does not contain any of '\
'the natural isotopes for that element.'\
.format(self.name)
raise ValueError(msg)
# If some, but not all, natural nuclides are in the library, add
# the mutual nuclides. For the absent nuclides, add them based on
# our knowledge of the common cross section libraries
# (ENDF, JEFF, and JENDL)
else:
# Add the mutual isotopes
for nuclide in mutual_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# Adjust the abundances for the absent nuclides
for nuclide in absent_nuclides:
if nuclide in ['O17', 'O18'] and 'O16' in mutual_nuclides:
abundances['O16'] += NATURAL_ABUNDANCE[nuclide]
elif nuclide == 'Ta180' and 'Ta181' in mutual_nuclides:
abundances['Ta181'] += NATURAL_ABUNDANCE[nuclide]
elif nuclide == 'W180' and 'W182' in mutual_nuclides:
abundances['W182'] += NATURAL_ABUNDANCE[nuclide]
else:
msg = 'Unsure how to partition natural abundance of ' \
'isotope {0} into other natural isotopes of ' \
'this element that are present in the cross ' \
'section library provided. Consider adding ' \
'the isotopes of this element individually.'
raise ValueError(msg)
# If a cross_section library is not present, expand the element into
# its natural nuclides
else:
for nuclide in natural_nuclides:
abundances[nuclide] = NATURAL_ABUNDANCE[nuclide]
# Modify mole fractions if enrichment provided
if enrichment is not None:
# Calculate the mass fractions of isotopes
abundances['U234'] = 0.008 * enrichment
abundances['U235'] = enrichment
abundances['U238'] = 100.0 - 1.008 * enrichment
# Convert the mass fractions to mole fractions
for nuclide in abundances.keys():
abundances[nuclide] /= atomic_mass(nuclide)
# Normalize the mole fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Compute the ratio of the nuclide atomic masses to the element
# atomic mass
if percent_type == 'wo':
# Compute the element atomic mass
element_am = 0.
for nuclide in abundances.keys():
element_am += atomic_mass(nuclide) * abundances[nuclide]
# Convert the molar fractions to mass fractions
for nuclide in abundances.keys():
abundances[nuclide] *= atomic_mass(nuclide) / element_am
# Normalize the mass fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Create a list of the isotopes in this element
isotopes = []
for nuclide, abundance in abundances.items():
nuc = openmc.Nuclide(nuclide)
nuc.scattering = self.scattering
isotopes.append((nuc, percent * abundance, percent_type))
return isotopes
import sys
import numpy as np
sys.path.insert(0, os.pardir)
sys.path.insert(0, os.path.join(os.pardir, os.pardir))
from openmc import Material
from openmc.data import NATURAL_ABUNDANCE, atomic_mass
if __name__ == '__main__':
# This test doesn't require an OpenMC run. We just need to make sure the
# element.expand() method expands elements with the proper nuclide
# compositions.
h_am = (NATURAL_ABUNDANCE['H1'] * atomic_mass('H1') +
NATURAL_ABUNDANCE['H2'] * atomic_mass('H2'))
o_am = (NATURAL_ABUNDANCE['O17'] * atomic_mass('O17') +
(NATURAL_ABUNDANCE['O16'] + NATURAL_ABUNDANCE['O18'])
* atomic_mass('O16'))
water_am = 2 * h_am + o_am
water = Material()
water.add_element('O', o_am / water_am, 'wo')
water.add_element('H', 2 * h_am / water_am, 'wo')
densities = water.get_nuclide_densities()
for nuc in densities.keys():
assert nuc in ('H1', 'H2', 'O16', 'O17')
if nuc in ('H1', 'H2'):
#!/usr/bin/env python
# Packages
import os
from copy import copy
from collections import OrderedDict
import numpy as np
import openmc
from openmc.data import atomic_mass, atomic_weight
import beavrs.constants as c
MB10 = atomic_mass('B10')
MB11 = atomic_mass('B11')
MU234 = atomic_mass('U234')
MU235 = atomic_mass('U235')
MU238 = atomic_mass('U238')
def openmc_materials(ppm):
# Initialize openmc material dictionary
mats = OrderedDict()
##############################################
# Create materials that use natural abundances
##############################################
# Create air material