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242 lines
7.9 KiB
Python
242 lines
7.9 KiB
Python
import os
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from pathlib import Path
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import numpy as np
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import pytest
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from uncertainties import ufloat
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import openmc
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from openmc.stats import Discrete, Point
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from tests import cdtemp
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@pytest.fixture
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def wws():
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# weight windows
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ww_files = ('ww_n.txt', 'ww_p.txt')
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cwd = Path(__file__).parent.absolute()
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ww_n_file, ww_p_file = [cwd / Path(f) for f in ww_files]
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# load pre-generated weight windows
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# (created using the same tally as above)
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ww_n_lower_bnds = np.loadtxt(ww_n_file)
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ww_p_lower_bnds = np.loadtxt(ww_p_file)
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# create a mesh matching the one used
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# to generate the weight windows
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ww_mesh = openmc.RegularMesh()
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ww_mesh.lower_left = (-240, -240, -240)
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ww_mesh.upper_right = (240, 240, 240)
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ww_mesh.dimension = (5, 6, 7)
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# energy bounds matching those of the
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# generated weight windows
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e_bnds = [0.0, 0.5, 2E7]
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ww_n = openmc.WeightWindows(ww_mesh,
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ww_n_lower_bnds,
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None,
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10.0,
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e_bnds,
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survival_ratio=1.01)
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ww_p = openmc.WeightWindows(ww_mesh,
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ww_p_lower_bnds,
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None,
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10.0,
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e_bnds,
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survival_ratio=1.01)
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return [ww_n, ww_p]
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@pytest.fixture
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def model():
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openmc.reset_auto_ids()
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model = openmc.Model()
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# materials (M4 steel alloy)
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m4 = openmc.Material()
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m4.set_density('g/cc', 2.3)
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m4.add_nuclide('H1', 0.168018676)
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m4.add_nuclide("H2", 1.93244e-05)
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m4.add_nuclide("O16", 0.561814465)
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m4.add_nuclide("O17", 0.00021401)
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m4.add_nuclide("Na23", 0.021365)
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m4.add_nuclide("Al27", 0.021343)
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m4.add_nuclide("Si28", 0.187439342)
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m4.add_nuclide("Si29", 0.009517714)
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m4.add_nuclide("Si30", 0.006273944)
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m4.add_nuclide("Ca40", 0.018026179)
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m4.add_nuclide("Ca42", 0.00012031)
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m4.add_nuclide("Ca43", 2.51033e-05)
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m4.add_nuclide("Ca44", 0.000387892)
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m4.add_nuclide("Ca46", 7.438e-07)
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m4.add_nuclide("Ca48", 3.47727e-05)
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m4.add_nuclide("Fe54", 0.000248179)
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m4.add_nuclide("Fe56", 0.003895875)
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m4.add_nuclide("Fe57", 8.99727e-05)
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m4.add_nuclide("Fe58", 1.19737e-05)
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s0 = openmc.Sphere(r=240)
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s1 = openmc.Sphere(r=250, boundary_type='vacuum')
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c0 = openmc.Cell(fill=m4, region=-s0)
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c1 = openmc.Cell(region=+s0 & -s1)
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model.geometry = openmc.Geometry([c0, c1])
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# settings
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settings = model.settings
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settings.run_mode = 'fixed source'
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settings.particles = 500
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settings.batches = 2
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settings.max_splits = 100
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settings.photon_transport = True
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space = Point((0.001, 0.001, 0.001))
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energy = Discrete([14E6], [1.0])
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settings.source = openmc.Source(space=space, energy=energy)
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# tally
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mesh = openmc.RegularMesh()
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mesh.lower_left = (-240, -240, -240)
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mesh.upper_right = (240, 240, 240)
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mesh.dimension = (3, 5, 7)
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mesh_filter = openmc.MeshFilter(mesh)
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e_bnds = [0.0, 0.5, 2E7]
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energy_filter = openmc.EnergyFilter(e_bnds)
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particle_filter = openmc.ParticleFilter(['neutron', 'photon'])
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tally = openmc.Tally()
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tally.filters = [mesh_filter, energy_filter, particle_filter]
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tally.scores = ['flux']
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model.tallies.append(tally)
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return model
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def test_weightwindows(model, wws):
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ww_files = ('ww_n.txt', 'ww_p.txt')
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cwd = Path(__file__).parent.absolute()
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filepaths = [cwd / Path(f) for f in ww_files]
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with cdtemp(filepaths):
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# run once with variance reduction off
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model.settings.weight_windows_on = False
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analog_sp = model.run()
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os.rename(analog_sp, 'statepoint.analog.h5')
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model.settings.weight_windows = wws
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# check that string form of the class can be created
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for ww in model.settings.weight_windows:
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str(ww)
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# run again with variance reduction on
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model.settings.weight_windows_on = True
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ww_sp = model.run()
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os.rename(ww_sp, 'statepoint.ww.h5')
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# load both statepoints and examine results
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asp = openmc.StatePoint('statepoint.analog.h5')
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wsp = openmc.StatePoint('statepoint.ww.h5')
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analog_tally = asp.tallies[1]
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ww_tally = wsp.tallies[1]
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def compare_results(particle, analog_tally, ww_tally):
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# get values from each of the tallies
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an_mean = analog_tally.get_values(filters=[openmc.ParticleFilter],
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filter_bins=[(particle,)])
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ww_mean = ww_tally.get_values(filters=[openmc.ParticleFilter],
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filter_bins=[(particle,)])
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# expect that more bins were scored with weight windows than
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# the analog run
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assert np.count_nonzero(an_mean) < np.count_nonzero(ww_mean)
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an_rel_err = analog_tally.get_values(filters=[openmc.ParticleFilter],
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filter_bins=[(particle,)],
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value='rel_err')
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ww_rel_err = ww_tally.get_values(filters=[openmc.ParticleFilter],
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filter_bins=[(particle,)],
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value='rel_err')
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an_rel_err[an_mean == 0.0] = 1.0
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ww_rel_err[ww_mean == 0.0] = 1.0
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an_avg_rel_err = np.mean(an_rel_err)
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ww_avg_rel_err = np.mean(ww_rel_err)
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# expect that the average relative error in the tally
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# decreases
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assert an_avg_rel_err > ww_avg_rel_err
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# ensure that the value of the mesh bin containing the
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# source is statistically similar in both runs
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an_std_dev = analog_tally.get_values(filters=[openmc.ParticleFilter],
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filter_bins=[(particle,)],
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value='std_dev')
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ww_std_dev = ww_tally.get_values(filters=[openmc.ParticleFilter],
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filter_bins=[(particle,)],
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value='std_dev')
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# index of the mesh bin containing the source for the higher
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# energy group
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source_bin_idx = (an_mean.shape[0]//2, 0, 0)
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an_source_bin = ufloat(an_mean[source_bin_idx],
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an_std_dev[source_bin_idx])
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ww_source_bin = ufloat(ww_mean[source_bin_idx],
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ww_std_dev[source_bin_idx])
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diff = an_source_bin - ww_source_bin
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# check that values are within two combined standard deviations
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assert abs(diff.nominal_value) / diff.std_dev < 2.0
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compare_results('neutron', analog_tally, ww_tally)
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compare_results('photon', analog_tally, ww_tally)
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def test_lower_ww_bounds_shape():
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"""checks that lower_ww_bounds is reshaped to the mesh dimension when set"""
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ww_mesh = openmc.RegularMesh()
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ww_mesh.lower_left = (-10, -10, -10)
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ww_mesh.upper_right = (10, 10, 10)
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ww_mesh.dimension = (2, 3, 4)
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ww = openmc.WeightWindows(
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mesh=ww_mesh,
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lower_ww_bounds=[1]*24,
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upper_bound_ratio=5,
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energy_bounds=(1, 1e40)
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)
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assert ww.lower_ww_bounds.shape == (2, 3, 4, 1)
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def test_roundtrip(run_in_tmpdir, model, wws):
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model.settings.weight_windows = wws
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# write the model with weight windows to XML
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model.export_to_xml()
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# ensure that they can be read successfully from XML and that they match the input values
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model_read = openmc.Model.from_xml()
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zipped_wws = zip(model.settings.weight_windows,
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model_read.settings.weight_windows)
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# ensure the lower bounds read in from the XML match those of the
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for ww_out, ww_in in zipped_wws:
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assert(ww_out == ww_in)
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