Reset DAGMC history when reviving from source.

src/particle.cpp

@@ -121,6 +121,9 @@ void Particle::from_source(const SourceSite* src)
   fission() = false;
   zero_flux_derivs();
   lifetime() = 0.0;
+#ifdef OPENMC_DAGMC_ENABLED
+  history().reset();
+#endif
 
   // Copy attributes from source bank site
   type() = src->particle;

tests/regression_tests/dagmc/weight_windows/model.xml

@@ -0,0 +1,58 @@
+<?xml version='1.0' encoding='utf-8'?>
+<model>
+  <materials>
+    <material id="1" name="shell">
+      <density value="7.8" units="g/cc"/>
+      <nuclide name="W180" ao="0.0012"/>
+      <nuclide name="W182" ao="0.265"/>
+      <nuclide name="W183" ao="0.1431"/>
+      <nuclide name="W184" ao="0.3064"/>
+      <nuclide name="W186" ao="0.2843"/>
+    </material>
+  </materials>
+  <geometry>
+    <dagmc_universe id="1" filename="nested_shell_geometry.h5m"/>
+  </geometry>
+  <settings>
+    <run_mode>fixed source</run_mode>
+    <particles>500</particles>
+    <batches>2</batches>
+    <max_lost_particles>1</max_lost_particles>
+    <source type="independent" strength="1.0" particle="neutron">
+      <space type="point">
+        <parameters>0.0 0.0 0.0</parameters>
+      </space>
+      <angle type="isotropic"/>
+      <energy type="discrete">
+        <parameters>14100000.0 1.0</parameters>
+      </energy>
+    </source>
+    <output>
+      <tallies>false</tallies>
+      <summary>false</summary>
+    </output>
+    <survival_biasing>false</survival_biasing>
+    <weight_windows id="1">
+      <mesh>10003</mesh>
+      <particle_type>neutron</particle_type>
+      <energy_bounds>0.0 1.7976931348623157e+308</energy_bounds>
+      <lower_ww_bounds>0.030750733294361156 0.056110505674355333 0.08187875047968339 0.1101743496347699 0.13982370013053508 0.17443799246829372 0.21576286623367483 0.26416659508033646 0.318574932646899 0.3804031702117963 0.42899359749256355 0.4954283294279403 0.49999999999999994 0.43432341070872266 0.38302303850488206 0.32148375935490886 0.2637416945702018 0.21498369367288853 0.17163611765361744 0.13832102142074995 0.10717772257151495 0.07986176041282561 0.05499644859408233 0.03058023506703803</lower_ww_bounds>
+      <upper_ww_bounds>0.15375366647180577 0.2805525283717767 0.40939375239841697 0.5508717481738494 0.6991185006526754 0.8721899623414686 1.0788143311683742 1.3208329754016823 1.592874663234495 1.9020158510589815 2.1449679874628176 2.4771416471397014 2.4999999999999996 2.1716170535436135 1.9151151925244103 1.6074187967745444 1.318708472851009 1.0749184683644426 0.8581805882680872 0.6916051071037498 0.5358886128575747 0.39930880206412805 0.27498224297041163 0.15290117533519015</upper_ww_bounds>
+      <survival_ratio>3.0</survival_ratio>
+      <max_lower_bound_ratio>1.0</max_lower_bound_ratio>
+      <max_split>10</max_split>
+      <weight_cutoff>1e-38</weight_cutoff>
+    </weight_windows>
+    <mesh id="10003" name="ww_mesh" type="rectilinear">
+      <x_grid>-60.0 -55.0 -50.0 -45.0 -40.0 -35.0 -30.0 -25.0 -20.0 -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0</x_grid>
+      <y_grid>-60.0 60.0</y_grid>
+      <z_grid>-60.0 60.0</z_grid>
+    </mesh>
+    <weight_windows_on>true</weight_windows_on>
+    <weight_window_checkpoints>
+      <collision>true</collision>
+      <surface>true</surface>
+    </weight_window_checkpoints>
+    <max_history_splits>10000000</max_history_splits>
+  </settings>
+  </model>

tests/regression_tests/dagmc/weight_windows/test.py

@@ -0,0 +1,40 @@
+from tests.testing_harness import TestHarness
+
+import openmc
+
+import pytest
+
+pytestmark = pytest.mark.skipif(
+    not openmc.lib._dagmc_enabled(),
+    reason="DAGMC CAD geometry is not enabled.")
+
+
+class DagmcWeightWindowsTestHarness(TestHarness):
+
+    def __init__(self):
+        super().__init__('')
+
+    def execute_test(self):
+        # this test merely needs to run OpenMC without error
+        try:
+            self._run_openmc()
+        finally:
+            self._cleanup()
+
+
+def test_dagmc_weight_windows_near_boundary():
+    """A regression test that ensures particle splitting near a boundary does
+    not result in lost particles due to a stale DAGMC history on the particle
+    object"""
+
+    # This DAGMC model consists of three nested cubes. The innermost cube
+    # contains a fusion neutron source. The two outer cubes are filled with
+    # tungsten. The entire model has weight windows defined on a mesh such that
+    # particles will be split as they move outward from the source. The
+    # outermost cubes are very similary in size, the outer cube is just slightly
+    # larger than the inner cube. This means that particles moving outward will
+    # frequently cross the boundary between the two cubes right after being
+    # split. This test ensures that no particles are lost due to a stale DAGMC
+    # history after splitting.
+    harness = DagmcWeightWindowsTestHarness()
+    harness.main()