diff --git a/AGENTS.md b/AGENTS.md
index 6ffb24a85f8..d663c09e579 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -213,6 +213,7 @@ Regression tests compare OpenMC output against reference data. **Prefer using ex
 - **PyAPITestHarness**: Standard harness for Python API tests. Compares `inputs_true.dat` (XML hash) and `results_true.dat` (statepoint k-eff and tally values). Requires `model.xml` generation.
 - **HashedPyAPITestHarness**: Like PyAPITestHarness but hashes the results for compact comparison
 - **TolerantPyAPITestHarness**: For tests with floating-point non-associativity (e.g., random ray solver with single precision). Uses relative tolerance comparisons.
+- **VTKTestHarness**: Like TolerantPyAPITestHarness but keeps one voxel plot and also compares the flux and source arrays of the random ray VTK files
 - **WeightWindowPyAPITestHarness**: Compares weight window bounds from `weight_windows.h5`
 - **CollisionTrackTestHarness**: Compares collision track data from `collision_track.h5` against `collision_track_true.h5`
 - **TestHarness**: Base harness for XML-based tests (no Python model building)
diff --git a/tests/regression_tests/random_ray_vtk/__init__.py b/tests/regression_tests/random_ray_vtk/__init__.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/regression_tests/random_ray_vtk/eigen_flat/inputs_true.dat b/tests/regression_tests/random_ray_vtk/eigen_flat/inputs_true.dat
new file mode 100644
index 00000000000..aa0a03f11e3
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/eigen_flat/inputs_true.dat
@@ -0,0 +1,119 @@
+<?xml version='1.0' encoding='utf-8'?>
+<model>
+  <materials>
+    <cross_sections>mgxs.h5</cross_sections>
+    <material id="1" name="UO2 fuel">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="UO2"/>
+    </material>
+    <material id="2" name="Water">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="LWTR"/>
+    </material>
+  </materials>
+  <geometry>
+    <cell id="1" name="fuel inner a" material="1" region="-2" universe="1"/>
+    <cell id="2" name="fuel inner b" material="1" region="2 -3" universe="1"/>
+    <cell id="3" name="fuel inner c" material="1" region="3 -1" universe="1"/>
+    <cell id="4" name="moderator inner a" material="2" region="1 -4" universe="1"/>
+    <cell id="5" name="moderator outer b" material="2" region="4 -5" universe="1"/>
+    <cell id="6" name="moderator outer c" material="2" region="5" universe="1"/>
+    <cell id="7" name="azimuthal_cell_0" fill="1" region="6 -7" universe="2"/>
+    <cell id="8" name="azimuthal_cell_1" fill="1" region="7 -8" universe="2"/>
+    <cell id="9" name="azimuthal_cell_2" fill="1" region="8 -9" universe="2"/>
+    <cell id="10" name="azimuthal_cell_3" fill="1" region="9 -10" universe="2"/>
+    <cell id="11" name="azimuthal_cell_4" fill="1" region="10 -11" universe="2"/>
+    <cell id="12" name="azimuthal_cell_5" fill="1" region="11 -12" universe="2"/>
+    <cell id="13" name="azimuthal_cell_6" fill="1" region="12 -13" universe="2"/>
+    <cell id="14" name="azimuthal_cell_7" fill="1" region="13 -6" universe="2"/>
+    <cell id="15" name="moderator infinite" material="2" universe="3"/>
+    <cell id="16" fill="4" universe="5"/>
+    <cell id="17" name="assembly" fill="6" region="14 -15 16 -17" universe="7"/>
+    <lattice id="4">
+      <pitch>0.126 0.126</pitch>
+      <dimension>10 10</dimension>
+      <lower_left>-0.63 -0.63</lower_left>
+      <universes>
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 </universes>
+    </lattice>
+    <lattice id="6">
+      <pitch>1.26 1.26</pitch>
+      <dimension>2 2</dimension>
+      <lower_left>-1.26 -1.26</lower_left>
+      <universes>
+2 2 
+2 5 </universes>
+    </lattice>
+    <surface id="1" name="Fuel OR" type="z-cylinder" coeffs="0.0 0.0 0.54"/>
+    <surface id="2" name="inner ring a" type="z-cylinder" coeffs="0.0 0.0 0.33"/>
+    <surface id="3" name="inner ring b" type="z-cylinder" coeffs="0.0 0.0 0.45"/>
+    <surface id="4" name="outer ring a" type="z-cylinder" coeffs="0.0 0.0 0.6"/>
+    <surface id="5" name="outer ring b" type="z-cylinder" coeffs="0.0 0.0 0.69"/>
+    <surface id="6" type="plane" coeffs="-0.0 1.0 0 0"/>
+    <surface id="7" type="plane" coeffs="-0.7071067811865475 0.7071067811865476 0 0"/>
+    <surface id="8" type="plane" coeffs="-1.0 6.123233995736766e-17 0 0"/>
+    <surface id="9" type="plane" coeffs="-0.7071067811865476 -0.7071067811865475 0 0"/>
+    <surface id="10" type="plane" coeffs="-1.2246467991473532e-16 -1.0 0 0"/>
+    <surface id="11" type="plane" coeffs="0.7071067811865475 -0.7071067811865477 0 0"/>
+    <surface id="12" type="plane" coeffs="1.0 -1.8369701987210297e-16 0 0"/>
+    <surface id="13" type="plane" coeffs="0.7071067811865477 0.7071067811865474 0 0"/>
+    <surface id="14" name="minimum x" type="x-plane" boundary="reflective" coeffs="-1.26"/>
+    <surface id="15" name="maximum x" type="x-plane" boundary="reflective" coeffs="1.26"/>
+    <surface id="16" name="minimum y" type="y-plane" boundary="reflective" coeffs="-1.26"/>
+    <surface id="17" name="maximum y" type="y-plane" boundary="reflective" coeffs="1.26"/>
+  </geometry>
+  <settings>
+    <run_mode>eigenvalue</run_mode>
+    <particles>100</particles>
+    <batches>15</batches>
+    <inactive>10</inactive>
+    <energy_mode>multi-group</energy_mode>
+    <random_ray>
+      <distance_active>100.0</distance_active>
+      <distance_inactive>20.0</distance_inactive>
+      <ray_source>
+        <source type="independent" strength="1.0" particle="neutron">
+          <space type="box">
+            <parameters>-1.26 -1.26 -1 1.26 1.26 1</parameters>
+          </space>
+        </source>
+      </ray_source>
+      <volume_normalized_flux_tallies>true</volume_normalized_flux_tallies>
+      <source_shape>flat</source_shape>
+    </random_ray>
+  </settings>
+  <tallies>
+    <mesh id="1">
+      <dimension>2 2</dimension>
+      <lower_left>-1.26 -1.26</lower_left>
+      <upper_right>1.26 1.26</upper_right>
+    </mesh>
+    <filter id="1" type="mesh">
+      <bins>1</bins>
+    </filter>
+    <filter id="2" type="energy">
+      <bins>1e-05 0.0635 10.0 100.0 1000.0 500000.0 1000000.0 20000000.0</bins>
+    </filter>
+    <tally id="1" name="Mesh tally">
+      <filters>1 2</filters>
+      <scores>flux fission nu-fission</scores>
+      <estimator>analog</estimator>
+    </tally>
+  </tallies>
+  <plots>
+    <plot id="1" color_by="cell" type="voxel">
+      <pixels>4 4 1</pixels>
+      <origin>0.0 0.0 0.0</origin>
+      <width>2.52 2.2 1.0</width>
+    </plot>
+  </plots>
+</model>
diff --git a/tests/regression_tests/random_ray_vtk/eigen_flat/results_true.dat b/tests/regression_tests/random_ray_vtk/eigen_flat/results_true.dat
new file mode 100644
index 00000000000..806a63f8f24
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/eigen_flat/results_true.dat
@@ -0,0 +1,307 @@
+k-combined:
+8.385858E-01 7.961547E-03
+tally 1:
+9.997473E-01
+1.999080E-01
+3.647422E-01
+2.660938E-02
+8.877096E-01
+1.576175E-01
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+1.866649E-03
+2.347461E-01
+1.105687E-02
+5.265210E-01
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+1.678151E-02
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+4.084283E-02
+3.361112E-04
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+1.058319E-01
+2.372143E-02
+1.130924E-04
+5.773322E-02
+6.698897E-04
+2.034631E+00
+8.302433E-01
+2.353203E-02
+1.110302E-04
+5.727296E-02
+6.576904E-04
+5.001687E+00
+5.005258E+00
+7.579105E-03
+1.149177E-05
+1.875397E-02
+7.036183E-05
+2.834778E+00
+1.607414E+00
+3.834521E-02
+2.941615E-04
+1.066553E-01
+2.275769E-03
+1.611723E+00
+5.196217E-01
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+8.194565E-01
+1.347809E-01
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+5.714128E-01
+6.575095E-02
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+8.153101E-01
+1.335408E-01
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+2.091192E+00
+8.767382E-01
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+4.453434E+00
+3.968333E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+2.431845E+00
+1.183113E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+8.905758E-01
+1.586353E-01
+3.331207E-01
+2.220078E-02
+8.107490E-01
+1.315037E-01
+6.268509E-01
+7.885079E-02
+9.396812E-02
+1.771993E-03
+2.286996E-01
+1.049619E-02
+5.173457E-01
+5.394832E-02
+1.688778E-02
+5.749804E-05
+4.110147E-02
+3.405828E-04
+7.124040E-01
+1.020387E-01
+2.388444E-02
+1.147159E-04
+5.812995E-02
+6.795059E-04
+2.032381E+00
+8.284515E-01
+2.403817E-02
+1.159107E-04
+5.850482E-02
+6.866001E-04
+5.067094E+00
+5.137271E+00
+7.796326E-03
+1.216304E-05
+1.929146E-02
+7.447189E-05
+2.841004E+00
+1.614651E+00
+3.867346E-02
+2.993412E-04
+1.075683E-01
+2.315842E-03
+1.015547E+00
+2.062759E-01
+3.838848E-01
+2.947687E-02
+9.342987E-01
+1.746028E-01
+6.672749E-01
+8.936443E-02
+1.006583E-01
+2.034231E-03
+2.449822E-01
+1.204953E-02
+5.291946E-01
+5.643268E-02
+1.734659E-02
+6.066244E-05
+4.221813E-02
+3.593267E-04
+7.290085E-01
+1.068312E-01
+2.454848E-02
+1.212049E-04
+5.974609E-02
+7.179431E-04
+2.036377E+00
+8.317006E-01
+2.418100E-02
+1.173001E-04
+5.885242E-02
+6.948306E-04
+4.962731E+00
+4.927955E+00
+7.669319E-03
+1.176788E-05
+1.897719E-02
+7.205244E-05
+2.786561E+00
+1.553086E+00
+3.814412E-02
+2.910337E-04
+1.060959E-01
+2.251570E-03
+plot_1.vtk flux_group_0:
+6.047841E-01
+5.711319E-01
+4.951928E-01
+4.590153E-01
+5.740759E-01
+5.561564E-01
+4.807656E-01
+4.824558E-01
+5.537308E-01
+5.480924E-01
+5.269392E-01
+5.310346E-01
+5.827065E-01
+5.973359E-01
+5.721900E-01
+5.726148E-01
+plot_1.vtk flux_group_1:
+1.038274E+00
+1.001371E+00
+8.932310E-01
+8.592597E-01
+1.014427E+00
+9.978791E-01
+8.974706E-01
+8.882848E-01
+1.005788E+00
+9.980367E-01
+9.658100E-01
+9.644631E-01
+1.033631E+00
+1.037318E+00
+1.016194E+00
+1.013432E+00
+plot_1.vtk flux_group_2:
+4.011087E-01
+4.046554E-01
+4.185627E-01
+4.192794E-01
+4.057611E-01
+4.070032E-01
+4.190576E-01
+4.184709E-01
+4.070420E-01
+4.075695E-01
+4.095736E-01
+4.090147E-01
+4.023955E-01
+4.013609E-01
+4.036887E-01
+4.033708E-01
+plot_1.vtk flux_group_3:
+1.387600E-01
+1.443710E-01
+1.629735E-01
+1.672593E-01
+1.424673E-01
+1.447999E-01
+1.620244E-01
+1.634913E-01
+1.430857E-01
+1.444860E-01
+1.497037E-01
+1.500004E-01
+1.381710E-01
+1.383021E-01
+1.410722E-01
+1.416524E-01
+plot_1.vtk flux_group_4:
+1.030079E-01
+1.056793E-01
+1.141604E-01
+1.170721E-01
+1.040339E-01
+1.052448E-01
+1.130806E-01
+1.144893E-01
+1.038706E-01
+1.045272E-01
+1.077177E-01
+1.080884E-01
+1.021949E-01
+1.021573E-01
+1.042055E-01
+1.046197E-01
+plot_1.vtk flux_group_5:
+1.253927E-01
+1.329089E-01
+1.632254E-01
+1.749505E-01
+1.277737E-01
+1.309657E-01
+1.572222E-01
+1.647295E-01
+1.257295E-01
+1.277221E-01
+1.384313E-01
+1.400886E-01
+1.214211E-01
+1.218412E-01
+1.281489E-01
+1.294892E-01
+plot_1.vtk flux_group_6:
+1.785199E-01
+2.003826E-01
+3.198731E-01
+3.642592E-01
+1.850330E-01
+1.936853E-01
+2.944633E-01
+3.248951E-01
+1.762112E-01
+1.817605E-01
+2.155434E-01
+2.207258E-01
+1.637172E-01
+1.660025E-01
+1.839652E-01
+1.880769E-01
+plot_1.vtk total_fission_source:
+6.118426E-02
+6.643250E-02
+0.000000E+00
+0.000000E+00
+6.266493E-02
+6.472900E-02
+0.000000E+00
+0.000000E+00
+6.045268E-02
+6.181088E-02
+6.998502E-02
+7.127898E-02
+5.747691E-02
+5.810902E-02
+6.241708E-02
+6.343340E-02
diff --git a/tests/regression_tests/random_ray_vtk/eigen_linear/inputs_true.dat b/tests/regression_tests/random_ray_vtk/eigen_linear/inputs_true.dat
new file mode 100644
index 00000000000..608ff1bc6cf
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/eigen_linear/inputs_true.dat
@@ -0,0 +1,119 @@
+<?xml version='1.0' encoding='utf-8'?>
+<model>
+  <materials>
+    <cross_sections>mgxs.h5</cross_sections>
+    <material id="1" name="UO2 fuel">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="UO2"/>
+    </material>
+    <material id="2" name="Water">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="LWTR"/>
+    </material>
+  </materials>
+  <geometry>
+    <cell id="1" name="fuel inner a" material="1" region="-2" universe="1"/>
+    <cell id="2" name="fuel inner b" material="1" region="2 -3" universe="1"/>
+    <cell id="3" name="fuel inner c" material="1" region="3 -1" universe="1"/>
+    <cell id="4" name="moderator inner a" material="2" region="1 -4" universe="1"/>
+    <cell id="5" name="moderator outer b" material="2" region="4 -5" universe="1"/>
+    <cell id="6" name="moderator outer c" material="2" region="5" universe="1"/>
+    <cell id="7" name="azimuthal_cell_0" fill="1" region="6 -7" universe="2"/>
+    <cell id="8" name="azimuthal_cell_1" fill="1" region="7 -8" universe="2"/>
+    <cell id="9" name="azimuthal_cell_2" fill="1" region="8 -9" universe="2"/>
+    <cell id="10" name="azimuthal_cell_3" fill="1" region="9 -10" universe="2"/>
+    <cell id="11" name="azimuthal_cell_4" fill="1" region="10 -11" universe="2"/>
+    <cell id="12" name="azimuthal_cell_5" fill="1" region="11 -12" universe="2"/>
+    <cell id="13" name="azimuthal_cell_6" fill="1" region="12 -13" universe="2"/>
+    <cell id="14" name="azimuthal_cell_7" fill="1" region="13 -6" universe="2"/>
+    <cell id="15" name="moderator infinite" material="2" universe="3"/>
+    <cell id="16" fill="4" universe="5"/>
+    <cell id="17" name="assembly" fill="6" region="14 -15 16 -17" universe="7"/>
+    <lattice id="4">
+      <pitch>0.126 0.126</pitch>
+      <dimension>10 10</dimension>
+      <lower_left>-0.63 -0.63</lower_left>
+      <universes>
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 </universes>
+    </lattice>
+    <lattice id="6">
+      <pitch>1.26 1.26</pitch>
+      <dimension>2 2</dimension>
+      <lower_left>-1.26 -1.26</lower_left>
+      <universes>
+2 2 
+2 5 </universes>
+    </lattice>
+    <surface id="1" name="Fuel OR" type="z-cylinder" coeffs="0.0 0.0 0.54"/>
+    <surface id="2" name="inner ring a" type="z-cylinder" coeffs="0.0 0.0 0.33"/>
+    <surface id="3" name="inner ring b" type="z-cylinder" coeffs="0.0 0.0 0.45"/>
+    <surface id="4" name="outer ring a" type="z-cylinder" coeffs="0.0 0.0 0.6"/>
+    <surface id="5" name="outer ring b" type="z-cylinder" coeffs="0.0 0.0 0.69"/>
+    <surface id="6" type="plane" coeffs="-0.0 1.0 0 0"/>
+    <surface id="7" type="plane" coeffs="-0.7071067811865475 0.7071067811865476 0 0"/>
+    <surface id="8" type="plane" coeffs="-1.0 6.123233995736766e-17 0 0"/>
+    <surface id="9" type="plane" coeffs="-0.7071067811865476 -0.7071067811865475 0 0"/>
+    <surface id="10" type="plane" coeffs="-1.2246467991473532e-16 -1.0 0 0"/>
+    <surface id="11" type="plane" coeffs="0.7071067811865475 -0.7071067811865477 0 0"/>
+    <surface id="12" type="plane" coeffs="1.0 -1.8369701987210297e-16 0 0"/>
+    <surface id="13" type="plane" coeffs="0.7071067811865477 0.7071067811865474 0 0"/>
+    <surface id="14" name="minimum x" type="x-plane" boundary="reflective" coeffs="-1.26"/>
+    <surface id="15" name="maximum x" type="x-plane" boundary="reflective" coeffs="1.26"/>
+    <surface id="16" name="minimum y" type="y-plane" boundary="reflective" coeffs="-1.26"/>
+    <surface id="17" name="maximum y" type="y-plane" boundary="reflective" coeffs="1.26"/>
+  </geometry>
+  <settings>
+    <run_mode>eigenvalue</run_mode>
+    <particles>100</particles>
+    <batches>15</batches>
+    <inactive>10</inactive>
+    <energy_mode>multi-group</energy_mode>
+    <random_ray>
+      <distance_active>100.0</distance_active>
+      <distance_inactive>20.0</distance_inactive>
+      <ray_source>
+        <source type="independent" strength="1.0" particle="neutron">
+          <space type="box">
+            <parameters>-1.26 -1.26 -1 1.26 1.26 1</parameters>
+          </space>
+        </source>
+      </ray_source>
+      <volume_normalized_flux_tallies>true</volume_normalized_flux_tallies>
+      <source_shape>linear</source_shape>
+    </random_ray>
+  </settings>
+  <tallies>
+    <mesh id="1">
+      <dimension>2 2</dimension>
+      <lower_left>-1.26 -1.26</lower_left>
+      <upper_right>1.26 1.26</upper_right>
+    </mesh>
+    <filter id="1" type="mesh">
+      <bins>1</bins>
+    </filter>
+    <filter id="2" type="energy">
+      <bins>1e-05 0.0635 10.0 100.0 1000.0 500000.0 1000000.0 20000000.0</bins>
+    </filter>
+    <tally id="1" name="Mesh tally">
+      <filters>1 2</filters>
+      <scores>flux fission nu-fission</scores>
+      <estimator>analog</estimator>
+    </tally>
+  </tallies>
+  <plots>
+    <plot id="1" color_by="cell" type="voxel">
+      <pixels>4 4 1</pixels>
+      <origin>0.0 0.0 0.0</origin>
+      <width>2.52 2.2 1.0</width>
+    </plot>
+  </plots>
+</model>
diff --git a/tests/regression_tests/random_ray_vtk/eigen_linear/results_true.dat b/tests/regression_tests/random_ray_vtk/eigen_linear/results_true.dat
new file mode 100644
index 00000000000..1a20c887823
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/eigen_linear/results_true.dat
@@ -0,0 +1,307 @@
+k-combined:
+8.362993E-01 7.089862E-03
+tally 1:
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+plot_1.vtk flux_group_1:
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+plot_1.vtk flux_group_2:
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+plot_1.vtk flux_group_3:
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+plot_1.vtk flux_group_4:
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+plot_1.vtk flux_group_5:
+1.255157E-01
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+plot_1.vtk flux_group_6:
+1.781728E-01
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+plot_1.vtk total_fission_source:
+6.121743E-02
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diff --git a/tests/regression_tests/random_ray_vtk/fs_flat/inputs_true.dat b/tests/regression_tests/random_ray_vtk/fs_flat/inputs_true.dat
new file mode 100644
index 00000000000..7789abc0e6d
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/fs_flat/inputs_true.dat
@@ -0,0 +1,254 @@
+<?xml version='1.0' encoding='utf-8'?>
+<model>
+  <materials>
+    <cross_sections>mgxs.h5</cross_sections>
+    <material id="1" name="source">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="source"/>
+    </material>
+    <material id="2" name="void">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="void"/>
+    </material>
+    <material id="3" name="absorber">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="absorber"/>
+    </material>
+  </materials>
+  <geometry>
+    <cell id="1" name="infinite source region" material="1" universe="1"/>
+    <cell id="2" name="infinite void region" material="2" universe="2"/>
+    <cell id="3" name="infinite absorber region" material="3" universe="3"/>
+    <cell id="4" fill="4" universe="5"/>
+    <cell id="5" name="full domain" fill="5" region="1 -2 3 -4 5 -6" universe="6"/>
+    <lattice id="4">
+      <pitch>2.5 2.5 2.5</pitch>
+      <dimension>12 12 12</dimension>
+      <lower_left>0.0 0.0 0.0</lower_left>
+      <universes>
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+1 1 2 2 2 2 2 2 2 2 3 3 
+1 1 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+1 1 2 2 2 2 2 2 2 2 3 3 
+1 1 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
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+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
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+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
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+2 2 2 2 2 2 2 2 2 2 3 3 
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+
+3 3 3 3 3 3 3 3 3 3 3 3 
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+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
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+
+3 3 3 3 3 3 3 3 3 3 3 3 
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+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
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+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
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+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 </universes>
+    </lattice>
+    <surface id="1" type="x-plane" boundary="reflective" coeffs="0.0"/>
+    <surface id="2" type="x-plane" boundary="vacuum" coeffs="30.0"/>
+    <surface id="3" type="y-plane" boundary="reflective" coeffs="0.0"/>
+    <surface id="4" type="y-plane" boundary="vacuum" coeffs="30.0"/>
+    <surface id="5" type="z-plane" boundary="reflective" coeffs="0.0"/>
+    <surface id="6" type="z-plane" boundary="vacuum" coeffs="30.0"/>
+  </geometry>
+  <settings>
+    <run_mode>fixed source</run_mode>
+    <particles>90</particles>
+    <batches>15</batches>
+    <inactive>10</inactive>
+    <source type="independent" strength="3.14" particle="neutron">
+      <energy type="discrete">
+        <parameters>100.0 1.0</parameters>
+      </energy>
+      <constraints>
+        <domain_type>universe</domain_type>
+        <domain_ids>1</domain_ids>
+      </constraints>
+    </source>
+    <energy_mode>multi-group</energy_mode>
+    <random_ray>
+      <distance_active>500.0</distance_active>
+      <distance_inactive>100.0</distance_inactive>
+      <ray_source>
+        <source type="independent" strength="1.0" particle="neutron">
+          <space type="box">
+            <parameters>0.0 0.0 0.0 30.0 30.0 30.0</parameters>
+          </space>
+        </source>
+      </ray_source>
+      <volume_normalized_flux_tallies>true</volume_normalized_flux_tallies>
+      <source_shape>flat</source_shape>
+    </random_ray>
+  </settings>
+  <tallies>
+    <filter id="3" type="material">
+      <bins>1</bins>
+    </filter>
+    <filter id="2" type="material">
+      <bins>2</bins>
+    </filter>
+    <filter id="1" type="material">
+      <bins>3</bins>
+    </filter>
+    <tally id="3" name="Source Tally">
+      <filters>3</filters>
+      <scores>flux</scores>
+      <estimator>tracklength</estimator>
+    </tally>
+    <tally id="2" name="Void Tally">
+      <filters>2</filters>
+      <scores>flux</scores>
+      <estimator>tracklength</estimator>
+    </tally>
+    <tally id="1" name="Absorber Tally">
+      <filters>1</filters>
+      <scores>flux</scores>
+      <estimator>tracklength</estimator>
+    </tally>
+  </tallies>
+  <plots>
+    <plot id="1" color_by="cell" type="voxel">
+      <pixels>3 3 3</pixels>
+      <origin>12.75 12.75 12.75</origin>
+      <width>24.9 24.9 24.9</width>
+    </plot>
+  </plots>
+</model>
diff --git a/tests/regression_tests/random_ray_vtk/fs_flat/results_true.dat b/tests/regression_tests/random_ray_vtk/fs_flat/results_true.dat
new file mode 100644
index 00000000000..ea29082605b
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/fs_flat/results_true.dat
@@ -0,0 +1,65 @@
+tally 1:
+5.364815E-01
+5.764087E-02
+tally 2:
+2.635573E-02
+1.416744E-04
+tally 3:
+1.885527E-03
+7.311352E-07
+plot_1.vtk flux_group_0:
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+plot_1.vtk external_source:
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+0.000000E+00
+0.000000E+00
+0.000000E+00
diff --git a/tests/regression_tests/random_ray_vtk/fs_linear/inputs_true.dat b/tests/regression_tests/random_ray_vtk/fs_linear/inputs_true.dat
new file mode 100644
index 00000000000..bdccc415599
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/fs_linear/inputs_true.dat
@@ -0,0 +1,254 @@
+<?xml version='1.0' encoding='utf-8'?>
+<model>
+  <materials>
+    <cross_sections>mgxs.h5</cross_sections>
+    <material id="1" name="source">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="source"/>
+    </material>
+    <material id="2" name="void">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="void"/>
+    </material>
+    <material id="3" name="absorber">
+      <density value="1.0" units="macro"/>
+      <macroscopic name="absorber"/>
+    </material>
+  </materials>
+  <geometry>
+    <cell id="1" name="infinite source region" material="1" universe="1"/>
+    <cell id="2" name="infinite void region" material="2" universe="2"/>
+    <cell id="3" name="infinite absorber region" material="3" universe="3"/>
+    <cell id="4" fill="4" universe="5"/>
+    <cell id="5" name="full domain" fill="5" region="1 -2 3 -4 5 -6" universe="6"/>
+    <lattice id="4">
+      <pitch>2.5 2.5 2.5</pitch>
+      <dimension>12 12 12</dimension>
+      <lower_left>0.0 0.0 0.0</lower_left>
+      <universes>
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+1 1 2 2 2 2 2 2 2 2 3 3 
+1 1 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+1 1 2 2 2 2 2 2 2 2 3 3 
+1 1 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+2 2 2 2 2 2 2 2 2 2 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 
+3 3 3 3 3 3 3 3 3 3 3 3 </universes>
+    </lattice>
+    <surface id="1" type="x-plane" boundary="reflective" coeffs="0.0"/>
+    <surface id="2" type="x-plane" boundary="vacuum" coeffs="30.0"/>
+    <surface id="3" type="y-plane" boundary="reflective" coeffs="0.0"/>
+    <surface id="4" type="y-plane" boundary="vacuum" coeffs="30.0"/>
+    <surface id="5" type="z-plane" boundary="reflective" coeffs="0.0"/>
+    <surface id="6" type="z-plane" boundary="vacuum" coeffs="30.0"/>
+  </geometry>
+  <settings>
+    <run_mode>fixed source</run_mode>
+    <particles>90</particles>
+    <batches>15</batches>
+    <inactive>10</inactive>
+    <source type="independent" strength="3.14" particle="neutron">
+      <energy type="discrete">
+        <parameters>100.0 1.0</parameters>
+      </energy>
+      <constraints>
+        <domain_type>universe</domain_type>
+        <domain_ids>1</domain_ids>
+      </constraints>
+    </source>
+    <energy_mode>multi-group</energy_mode>
+    <random_ray>
+      <distance_active>500.0</distance_active>
+      <distance_inactive>100.0</distance_inactive>
+      <ray_source>
+        <source type="independent" strength="1.0" particle="neutron">
+          <space type="box">
+            <parameters>0.0 0.0 0.0 30.0 30.0 30.0</parameters>
+          </space>
+        </source>
+      </ray_source>
+      <volume_normalized_flux_tallies>true</volume_normalized_flux_tallies>
+      <source_shape>linear</source_shape>
+    </random_ray>
+  </settings>
+  <tallies>
+    <filter id="3" type="material">
+      <bins>1</bins>
+    </filter>
+    <filter id="2" type="material">
+      <bins>2</bins>
+    </filter>
+    <filter id="1" type="material">
+      <bins>3</bins>
+    </filter>
+    <tally id="3" name="Source Tally">
+      <filters>3</filters>
+      <scores>flux</scores>
+      <estimator>tracklength</estimator>
+    </tally>
+    <tally id="2" name="Void Tally">
+      <filters>2</filters>
+      <scores>flux</scores>
+      <estimator>tracklength</estimator>
+    </tally>
+    <tally id="1" name="Absorber Tally">
+      <filters>1</filters>
+      <scores>flux</scores>
+      <estimator>tracklength</estimator>
+    </tally>
+  </tallies>
+  <plots>
+    <plot id="1" color_by="cell" type="voxel">
+      <pixels>3 3 3</pixels>
+      <origin>12.75 12.75 12.75</origin>
+      <width>24.9 24.9 24.9</width>
+    </plot>
+  </plots>
+</model>
diff --git a/tests/regression_tests/random_ray_vtk/fs_linear/results_true.dat b/tests/regression_tests/random_ray_vtk/fs_linear/results_true.dat
new file mode 100644
index 00000000000..df8a6b1253d
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/fs_linear/results_true.dat
@@ -0,0 +1,65 @@
+tally 1:
+5.422753E-01
+5.888788E-02
+tally 2:
+2.666460E-02
+1.448679E-04
+tally 3:
+1.874218E-03
+7.240497E-07
+plot_1.vtk flux_group_0:
+9.133315E-03
+2.470312E-02
+8.639651E-03
+2.068152E-02
+1.821846E-02
+3.879083E-04
+3.972599E-03
+1.556799E-02
+1.563231E-03
+6.325816E-03
+6.817768E-03
+8.863986E-03
+5.132107E-04
+2.907239E-03
+2.343546E-02
+7.046433E-03
+1.158762E-02
+2.694198E-04
+2.483241E-03
+8.822081E-04
+2.509553E-04
+1.298585E-02
+1.076230E-03
+1.506452E-03
+5.795310E-03
+3.468050E-04
+2.400703E-03
+plot_1.vtk external_source:
+3.140000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
+0.000000E+00
diff --git a/tests/regression_tests/random_ray_vtk/test.py b/tests/regression_tests/random_ray_vtk/test.py
new file mode 100644
index 00000000000..1b78e1777c7
--- /dev/null
+++ b/tests/regression_tests/random_ray_vtk/test.py
@@ -0,0 +1,42 @@
+import os
+
+import openmc
+from openmc.examples import random_ray_lattice, random_ray_three_region_cube
+from openmc.utility_funcs import change_directory
+import pytest
+
+from tests.testing_harness import VTKTestHarness
+
+
+class MGXSTestHarness(VTKTestHarness):
+    def _cleanup(self):
+        super()._cleanup()
+        f = 'mgxs.h5'
+        if os.path.exists(f):
+            os.remove(f)
+
+
+@pytest.mark.parametrize("shape", ["flat", "linear"])
+@pytest.mark.parametrize("run_mode", ["eigen", "fs"])
+def test_random_ray_vtk(run_mode, shape):
+    with change_directory(f'{run_mode}_{shape}'):
+        openmc.reset_auto_ids()
+        plot = openmc.VoxelPlot()
+        if run_mode == 'eigen':
+            model = random_ray_lattice()
+            # Voxel centers off the azimuthal planes and rings of the pins
+            plot.width = (2.52, 2.2, 1.0)
+            plot.pixels = (4, 4, 1)
+        else:
+            model = random_ray_three_region_cube()
+            # Voxel centers off the 2.5 cm lattice planes
+            plot.origin = (12.75, 12.75, 12.75)
+            plot.width = (24.9, 24.9, 24.9)
+            plot.pixels = (3, 3, 3)
+        model.settings.random_ray['source_shape'] = shape
+        # The linear source keeps its gradients at zero for the first ten
+        # batches, so put all the active batches after them
+        model.settings.inactive = 10
+        model.settings.batches = 15
+        harness = MGXSTestHarness('statepoint.15.h5', model, plot)
+        harness.main()
diff --git a/tests/testing_harness.py b/tests/testing_harness.py
index 40c436b55a5..f4717c1c3a4 100644
--- a/tests/testing_harness.py
+++ b/tests/testing_harness.py
@@ -30,6 +30,21 @@ def colorize(diff):
             yield line
 
 
+def read_vtk_arrays(path):
+    """Read the point data arrays from a legacy binary VTK file."""
+    arrays = {}
+    with open(path, 'rb') as fh:
+        while line := fh.readline():
+            if line.startswith(b'POINT_DATA'):
+                n = int(line.split()[1])
+            elif line.startswith(b'SCALARS'):
+                _, name, dtype = line.decode().split()
+                fh.readline()  # LOOKUP_TABLE default
+                dtype = {'float': '>f4', 'int': '>i4'}[dtype]
+                arrays[name] = np.frombuffer(fh.read(4*n), dtype)
+    return arrays
+
+
 class TestHarness:
     """General class for running OpenMC regression tests."""
 
@@ -455,6 +470,40 @@ def _compare_results(self):
         assert compare, 'Results do not agree'
 
 
+class VTKTestHarness(TolerantPyAPITestHarness):
+    """Specialized harness for random ray tests that also check the flux and
+    source written to VTK files for a voxel plot.
+
+    """
+
+    def __init__(self, statepoint_name, model, plot):
+        super().__init__(statepoint_name, model)
+        # The base class removes all plots, so add back the one being tested
+        self._model.plots = [plot]
+
+    def _get_results(self):
+        """Digest the statepoint and VTK files and return as a string."""
+        outstr = super()._get_results()
+        # Adjoint runs also write the forward solve, to a .forward.vtk file
+        for vtk_file in sorted(glob.glob('*.vtk')):
+            for name, values in read_vtk_arrays(vtk_file).items():
+                # Compare the flux and source fields. The other arrays are
+                # random colors (FSRs, rank_subdomains), timings
+                # (measured_load), or not under test (Materials,
+                # weight_window_lower)
+                if name.startswith('flux_group_') or name in (
+                        'total_fission_source', 'external_source'):
+                    outstr += f'{vtk_file} {name}:\n'
+                    outstr += ''.join(f'{x:12.6E}\n' for x in values)
+        return outstr
+
+    def _cleanup(self):
+        """Delete the VTK files."""
+        super()._cleanup()
+        for f in glob.glob('*.vtk'):
+            os.remove(f)
+
+
 class WeightWindowPyAPITestHarness(PyAPITestHarness):
     def _get_results(self):
         """Digest info in the weight window file and return as a string."""
diff --git a/tests/unit_tests/test_random_ray_vtk_normalization.py b/tests/unit_tests/test_random_ray_vtk_normalization.py
deleted file mode 100644
index b6fa527bdc3..00000000000
--- a/tests/unit_tests/test_random_ray_vtk_normalization.py
+++ /dev/null
@@ -1,44 +0,0 @@
-import math
-import struct
-
-import openmc
-from openmc.examples import random_ray_three_region_cube
-from tests.regression_tests import config
-
-
-def _read_vtk_flux(path, group, count):
-    with open(path, 'rb') as fh:
-        data = fh.read()
-
-    marker = (f'SCALARS flux_group_{group} float\n'
-              'LOOKUP_TABLE default\n').encode()
-    start = data.index(marker) + len(marker)
-    end = start + count * struct.calcsize('>f')
-    return struct.unpack(f'>{count}f', data[start:end])
-
-
-def test_random_ray_vtk_normalization(run_in_tmpdir):
-    openmc.reset_auto_ids()
-    model = random_ray_three_region_cube()
-    model.settings.random_ray['source_shape'] = 'linear'
-    model.settings.inactive = 5
-    model.settings.batches = 10
-
-    plot = openmc.VoxelPlot()
-    plot.filename = 'random_ray_vtk_normalization.h5'
-    plot.origin = (2.5, 2.5, 2.5)
-    plot.width = (5.0, 5.0, 5.0)
-    plot.pixels = (2, 2, 2)
-    model.plots = [plot]
-
-    model.run(openmc_exec=config['exe'])
-
-    with openmc.StatePoint('statepoint.10.h5') as statepoint:
-        source_tally = statepoint.get_tally(name='Source Tally')
-        tally_flux = source_tally.mean.ravel()[0]
-
-    vtk_flux = _read_vtk_flux(
-        'random_ray_vtk_normalization.vtk', group=0, count=8)
-    plot_flux = sum(vtk_flux) / len(vtk_flux)
-
-    assert math.isclose(plot_flux, tally_flux, rel_tol=0.15)