Tests: Adding unit test for weight windows.

tests/unit_tests/weightwindows/test.py

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+import os
+from pathlib import Path
+
+import numpy as np
+import pytest
+
+import openmc
+from openmc.stats import Discrete, Point
+
+from tests import cdtemp
+
+@pytest.fixture
+def model():
+    model = openmc.Model()
+
+    # materials (M4 steel alloy)
+    m4 = openmc.Material()
+    m4.set_density('g/cc', 2.3)
+    m4.add_nuclide('H1', 0.168018676)
+    m4.add_nuclide("H2", 1.93244e-05)
+    m4.add_nuclide("O16", 0.561814465)
+    m4.add_nuclide("O17", 0.00021401)
+    m4.add_nuclide("Na23", 0.021365)
+    m4.add_nuclide("Al27", 0.021343)
+    m4.add_nuclide("Si28", 0.187439342)
+    m4.add_nuclide("Si29", 0.009517714)
+    m4.add_nuclide("Si30", 0.006273944)
+    m4.add_nuclide("Ca40", 0.018026179)
+    m4.add_nuclide("Ca42", 0.00012031)
+    m4.add_nuclide("Ca43", 2.51033e-05)
+    m4.add_nuclide("Ca44", 0.000387892)
+    m4.add_nuclide("Ca46", 7.438e-07)
+    m4.add_nuclide("Ca48", 3.47727e-05)
+    m4.add_nuclide("Fe54", 0.000248179)
+    m4.add_nuclide("Fe56", 0.003895875)
+    m4.add_nuclide("Fe57", 8.99727e-05)
+    m4.add_nuclide("Fe58", 1.19737e-05)
+
+    s0 = openmc.Sphere(r=240)
+    s1 = openmc.Sphere(r=250, boundary_type='vacuum')
+
+    c0 = openmc.Cell(fill=m4, region=-s0)
+    c1 = openmc.Cell(region=+s0 & -s1)
+
+    model.geometry = openmc.Geometry([c0, c1])
+
+    # settings
+    settings = model.settings
+    settings.run_mode = 'fixed source'
+    settings.particles = 500
+    settings.batches = 2
+    settings.max_splits = 100
+    settings.photon_transport = True
+    space = Point((0.001, 0.001, 0.001))
+    energy = Discrete([14E6], [1.0])
+
+    settings.source = openmc.Source(space=space, energy=energy)
+
+    # tally
+    mesh = openmc.RegularMesh()
+    mesh.lower_left = (-240, -240, -240)
+    mesh.upper_right = (240, 240, 240)
+    mesh.dimension = (5, 10, 15)
+
+    mesh_filter = openmc.MeshFilter(mesh)
+
+    e_bnds = [0.0, 0.5, 2E7]
+    energy_filter = openmc.EnergyFilter(e_bnds)
+
+    particle_filter = openmc.ParticleFilter(['neutron', 'photon'])
+
+    tally = openmc.Tally()
+    tally.filters = [mesh_filter, energy_filter, particle_filter]
+    tally.scores = ['flux']
+
+    model.tallies.append(tally)
+
+    return model
+
+
+def test_weightwindows(model):
+
+    ww_files = ('ww_n.txt', 'ww_p.txt')
+    cwd = Path(__file__).parent.absolute()
+    filepaths = [cwd / Path(f) for f in ww_files]
+
+    with cdtemp(filepaths):
+        # run once with variance reduction off
+        model.settings.weight_windows_on = False
+        analog_sp = model.run()
+        os.rename(analog_sp, 'statepoint.analog.h5')
+
+        # weight windows
+
+        # load pre-generated weight windows
+        # (created using the same tally as above)
+        ww_n_lower_bnds = np.loadtxt('ww_n.txt')
+        ww_p_lower_bnds = np.loadtxt('ww_p.txt')
+
+        # create a mesh matching the one used
+        # to generate the weight windows
+        ww_mesh = openmc.RegularMesh()
+        ww_mesh.lower_left = (-240, -240, -240)
+        ww_mesh.upper_right = (240, 240, 240)
+        ww_mesh.dimension = (5, 6, 7)
+
+        # energy bounds matching those of the
+        # generated weight windows
+        e_bnds = [0.0, 0.5, 2E7]
+
+        ww_n = openmc.WeightWindows(ww_mesh,
+                                    ww_n_lower_bnds,
+                                    None,
+                                    10.0,
+                                    e_bnds)
+
+        ww_p = openmc.WeightWindows(ww_mesh,
+                                    ww_p_lower_bnds,
+                                    None,
+                                    10.0,
+                                    e_bnds)
+
+        model.settings.weight_windows = [ww_n, ww_p]
+
+
+        # run again with variance reduction on
+        model.settings.weight_windows_on = True
+        ww_sp = model.run()
+        os.rename(ww_sp, 'statepoint.ww.h5')
+
+        # load both statepoints and examine results
+        asp = openmc.StatePoint('statepoint.analog.h5')
+        wsp = openmc.StatePoint('statepoint.ww.h5')
+
+        analog_tally = asp.tallies[1]
+        ww_tally = wsp.tallies[1]
+
+        def compare_results(particle, analog_tally, ww_tally):
+
+            # get values from each of the tallies
+            an_mean = analog_tally.get_values(filters=[openmc.ParticleFilter],
+                                              filter_bins=[(particle,)])
+            ww_mean = ww_tally.get_values(filters=[openmc.ParticleFilter],
+                                          filter_bins=[(particle,)])
+
+            # expect that more bins were scored with weight windows than
+            # the analog run
+            assert np.count_nonzero(an_mean) < np.count_nonzero(ww_mean)
+
+            an_rel_err = analog_tally.get_values(filters=[openmc.ParticleFilter],
+                                                filter_bins=[(particle,)],
+                                                value='rel_err')
+            ww_rel_err = ww_tally.get_values(filters=[openmc.ParticleFilter],
+                                                filter_bins=[(particle,)],
+                                                value='rel_err')
+
+            print(an_rel_err)
+            an_rel_err[an_mean == 0.0] = 1.0
+            ww_rel_err[ww_mean == 0.0] = 1.0
+
+            an_avg_rel_err = np.mean(an_rel_err)
+            ww_avg_rel_err = np.mean(ww_rel_err)
+
+            # expect that the average relative error in the tally
+            # decreases
+            assert an_avg_rel_err > ww_avg_rel_err
+
+        compare_results('neutron', analog_tally, ww_tally)
+        compare_results('photon', analog_tally, ww_tally)

tests/unit_tests/weightwindows/ww_n.txt

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+../../regression_tests/weightwindow/ww_n.txt

tests/unit_tests/weightwindows/ww_p.txt

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+../../regression_tests/weightwindow/ww_p.txt