Merge remote-tracking branch 'upstream/develop' into develop

CMakeLists.txt

@@ -116,9 +116,9 @@ if(CMAKE_Fortran_COMPILER_ID STREQUAL GNU)
   endif()
 
   # GCC compiler options
-  list(APPEND f90flags -cpp -std=f2008ts -fbacktrace -O2)
+  list(APPEND f90flags -cpp -std=f2008ts -fbacktrace -O2 -fstack-arrays)
   if(debug)
-    list(REMOVE_ITEM f90flags -O2)
+    list(REMOVE_ITEM f90flags -O2 -fstack-arrays)
     list(APPEND f90flags -g -Wall -Wno-unused-dummy-argument -pedantic
       -fbounds-check -ffpe-trap=invalid,overflow,underflow)
     list(APPEND ldflags -g)

openmc/executor.py

@@ -15,18 +15,22 @@ def _run(args, output, cwd):
                          stderr=subprocess.STDOUT, universal_newlines=True)
 
     # Capture and re-print OpenMC output in real-time
+    lines = []
     while True:
         # If OpenMC is finished, break loop
         line = p.stdout.readline()
         if not line and p.poll() is not None:
             break
 
+        lines.append(line)
         if output:
             # If user requested output, print to screen
             print(line, end='')
 
-    # Return the returncode (integer, zero if no problems encountered)
-    return p.returncode
+    # Raise an exception if return status is non-zero
+    if p.returncode != 0:
+        raise subprocess.CalledProcessError(p.returncode, ' '.join(args),
+                                            ''.join(lines))
 
 
 def plot_geometry(output=True, openmc_exec='openmc', cwd='.'):
@@ -41,8 +45,13 @@ def plot_geometry(output=True, openmc_exec='openmc', cwd='.'):
     cwd : str, optional
         Path to working directory to run in
 
+    Raises
+    ------
+    subprocess.CalledProcessError
+        If the `openmc` executable returns a non-zero status
+
     """
-    return _run([openmc_exec, '-p'], output, cwd)
+    _run([openmc_exec, '-p'], output, cwd)
 
 
 def plot_inline(plots, openmc_exec='openmc', cwd='.', convert_exec='convert'):
@@ -63,6 +72,11 @@ def plot_inline(plots, openmc_exec='openmc', cwd='.', convert_exec='convert'):
     convert_exec : str, optional
         Command that can convert PPM files into PNG files
 
+    Raises
+    ------
+    subprocess.CalledProcessError
+        If the `openmc` executable returns a non-zero status
+
     """
     from IPython.display import Image, display
 
@@ -121,6 +135,11 @@ def calculate_volumes(threads=None, output=True, cwd='.',
         Path to working directory to run in. Defaults to the current working
         directory.
 
+    Raises
+    ------
+    subprocess.CalledProcessError
+        If the `openmc` executable returns a non-zero status
+
     See Also
     --------
     openmc.VolumeCalculation
@@ -133,7 +152,7 @@ def calculate_volumes(threads=None, output=True, cwd='.',
     if mpi_args is not None:
         args = mpi_args + args
 
-    return _run(args, output, cwd)
+    _run(args, output, cwd)
 
 
 def run(particles=None, threads=None, geometry_debug=False,
@@ -167,8 +186,12 @@ def run(particles=None, threads=None, geometry_debug=False,
         MPI execute command and any additional MPI arguments to pass,
         e.g. ['mpiexec', '-n', '8'].
 
-    """
+    Raises
+    ------
+    subprocess.CalledProcessError
+        If the `openmc` executable returns a non-zero status
 
+    """
     args = [openmc_exec]
 
     if isinstance(particles, Integral) and particles > 0:
@@ -189,4 +212,4 @@ def run(particles=None, threads=None, geometry_debug=False,
     if mpi_args is not None:
         args = mpi_args + args
 
-    return _run(args, output, cwd)
+    _run(args, output, cwd)

src/cross_section.F90

@@ -42,7 +42,6 @@ contains
 
     ! Set all material macroscopic cross sections to zero
     material_xs % total          = ZERO
-    material_xs % elastic        = ZERO
     material_xs % absorption     = ZERO
     material_xs % fission        = ZERO
     material_xs % nu_fission     = ZERO
@@ -115,10 +114,6 @@ contains
         material_xs % total = material_xs % total + &
              atom_density * micro_xs(i_nuclide) % total
 
-        ! Add contributions to material macroscopic scattering cross section
-        material_xs % elastic = material_xs % elastic + &
-             atom_density * micro_xs(i_nuclide) % elastic
-
         ! Add contributions to material macroscopic absorption cross section
         material_xs % absorption = material_xs % absorption + &
              atom_density * micro_xs(i_nuclide) % absorption
@@ -162,6 +157,7 @@ contains
     real(8) :: sig_t, sig_a, sig_f ! Intermediate multipole variables
 
     ! Initialize cached cross sections to zero
+    micro_xs(i_nuclide) % elastic         = CACHE_INVALID
     micro_xs(i_nuclide) % thermal         = ZERO
     micro_xs(i_nuclide) % thermal_elastic = ZERO
 
@@ -182,13 +178,11 @@ contains
 
         micro_xs(i_nuclide) % total = sig_t
         micro_xs(i_nuclide) % absorption = sig_a
-        micro_xs(i_nuclide) % elastic = sig_t - sig_a
+        micro_xs(i_nuclide) % fission = sig_f
 
         if (nuc % fissionable) then
-          micro_xs(i_nuclide) % fission = sig_f
           micro_xs(i_nuclide) % nu_fission = sig_f * nuc % nu(E, EMISSION_TOTAL)
         else
-          micro_xs(i_nuclide) % fission    = ZERO
           micro_xs(i_nuclide) % nu_fission = ZERO
         end if
 
@@ -233,7 +227,7 @@ contains
           if (f > prn()) i_temp = i_temp + 1
         end select
 
-        associate (grid => nuc % grid(i_temp), xs => nuc % sum_xs(i_temp))
+        associate (grid => nuc % grid(i_temp), xs => nuc % xs(i_temp))
           ! Determine the energy grid index using a logarithmic mapping to
           ! reduce the energy range over which a binary search needs to be
           ! performed
@@ -266,25 +260,21 @@ contains
           micro_xs(i_nuclide) % interp_factor = f
 
           ! Calculate microscopic nuclide total cross section
-          micro_xs(i_nuclide) % total = (ONE - f) * xs % total(i_grid) &
-               + f * xs % total(i_grid + 1)
-
-          ! Calculate microscopic nuclide elastic cross section
-          micro_xs(i_nuclide) % elastic = (ONE - f) * xs % elastic(i_grid) &
-               + f * xs % elastic(i_grid + 1)
+          micro_xs(i_nuclide) % total = (ONE - f) * xs % value(XS_TOTAL,i_grid) &
+               + f * xs % value(XS_TOTAL,i_grid + 1)
 
           ! Calculate microscopic nuclide absorption cross section
-          micro_xs(i_nuclide) % absorption = (ONE - f) * xs % absorption( &
-               i_grid) + f * xs % absorption(i_grid + 1)
+          micro_xs(i_nuclide) % absorption = (ONE - f) * xs % value(XS_ABSORPTION, &
+               i_grid) + f * xs % value(XS_ABSORPTION,i_grid + 1)
 
           if (nuc % fissionable) then
             ! Calculate microscopic nuclide total cross section
-            micro_xs(i_nuclide) % fission = (ONE - f) * xs % fission(i_grid) &
-                 + f * xs % fission(i_grid + 1)
+            micro_xs(i_nuclide) % fission = (ONE - f) * xs % value(XS_FISSION,i_grid) &
+                 + f * xs % value(XS_FISSION,i_grid + 1)
 
             ! Calculate microscopic nuclide nu-fission cross section
-            micro_xs(i_nuclide) % nu_fission = (ONE - f) * xs % nu_fission( &
-                 i_grid) + f * xs % nu_fission(i_grid + 1)
+            micro_xs(i_nuclide) % nu_fission = (ONE - f) * xs % value(XS_NU_FISSION, &
+                 i_grid) + f * xs % value(XS_NU_FISSION,i_grid + 1)
           else
             micro_xs(i_nuclide) % fission         = ZERO
             micro_xs(i_nuclide) % nu_fission      = ZERO
@@ -451,6 +441,9 @@ contains
     micro_xs(i_nuclide) % thermal = sab_frac * (elastic + inelastic)
     micro_xs(i_nuclide) % thermal_elastic = sab_frac * elastic
 
+    ! Calculate free atom elastic cross section
+    call calculate_elastic_xs(i_nuclide)
+
     ! Correct total and elastic cross sections
     micro_xs(i_nuclide) % total = micro_xs(i_nuclide) % total &
          + micro_xs(i_nuclide) % thermal &
@@ -579,6 +572,7 @@ contains
 
       ! Multiply by smooth cross-section if needed
       if (urr % multiply_smooth) then
+        call calculate_elastic_xs(i_nuclide)
         elastic = elastic * micro_xs(i_nuclide) % elastic
         capture = capture * (micro_xs(i_nuclide) % absorption - &
              micro_xs(i_nuclide) % fission)
@@ -607,6 +601,36 @@ contains
 
   end subroutine calculate_urr_xs
 
+!===============================================================================
+! CALCULATE_ELASTIC_XS precalculates the free atom elastic scattering cross
+! section. Normally it is not needed until a collision actually occurs in a
+! material. However, in the thermal and unresolved resonance regions, we have to
+! calculate it early to adjust the total cross section correctly.
+!===============================================================================
+
+  subroutine calculate_elastic_xs(i_nuclide)
+    integer, intent(in) :: i_nuclide
+
+    integer :: i_temp
+    integer :: i_grid
+    real(8) :: f
+
+    ! Get temperature index, grid index, and interpolation factor
+    i_temp =  micro_xs(i_nuclide) % index_temp
+    i_grid =  micro_xs(i_nuclide) % index_grid
+    f      =  micro_xs(i_nuclide) % interp_factor
+
+    if (i_temp > 0) then
+      associate (xs => nuclides(i_nuclide) % reactions(1) % xs(i_temp) % value)
+        micro_xs(i_nuclide) % elastic = (ONE - f)*xs(i_grid) + f*xs(i_grid + 1)
+      end associate
+    else
+      ! For multipole, elastic is total - absorption
+      micro_xs(i_nuclide) % elastic = micro_xs(i_nuclide) % total - &
+           micro_xs(i_nuclide) % absorption
+    end if
+  end subroutine calculate_elastic_xs
+
 !===============================================================================
 ! MULTIPOLE_EVAL evaluates the windowed multipole equations for cross
 ! sections in the resolved resonance regions

src/nuclide_header.F90

@@ -36,13 +36,18 @@ module nuclide_header
     real(8), allocatable :: energy(:)     ! energy values corresponding to xs
   end type EnergyGrid
 
+  ! Positions for first dimension of Nuclide % xs
+  integer, parameter :: &
+       XS_TOTAL      = 1, &
+       XS_ABSORPTION = 2, &
+       XS_FISSION    = 3, &
+       XS_NU_FISSION = 4
+
+  ! The array within SumXS is of shape (4, n_energy) where the first dimension
+  ! corresponds to the following values: 1) total, 2) absorption (MT > 100), 3)
+  ! fission, 4) neutron production
   type SumXS
-    real(8), allocatable :: total(:)      ! total cross section
-    real(8), allocatable :: elastic(:)    ! elastic scattering
-    real(8), allocatable :: fission(:)    ! fission
-    real(8), allocatable :: nu_fission(:) ! neutron production
-    real(8), allocatable :: absorption(:) ! absorption (MT > 100)
-    real(8), allocatable :: heating(:)    ! heating
+    real(8), allocatable :: value(:,:)
   end type SumXS
 
   type :: Nuclide
@@ -61,7 +66,7 @@ module nuclide_header
     type(EnergyGrid), allocatable :: grid(:)
 
     ! Microscopic cross sections
-    type(SumXS), allocatable :: sum_xs(:)
+    type(SumXS), allocatable :: xs(:)
 
     ! Resonance scattering info
     logical              :: resonant = .false. ! resonant scatterer?
@@ -110,14 +115,19 @@ module nuclide_header
 ! nuclide at the current energy
 !===============================================================================
 
+  ! Arbitrary value to indicate invalid cache state for elastic scattering
+  ! (NuclideMicroXS % elastic)
+  real(8), parameter :: CACHE_INVALID = dble(Z"FFE0000000000000")
+
   type NuclideMicroXS
     ! Microscopic cross sections in barns
     real(8) :: total
-    real(8) :: elastic          ! If sab_frac is not 1 or 0, then this value is
-                                !   averaged over bound and non-bound nuclei
     real(8) :: absorption       ! absorption (disappearance)
     real(8) :: fission          ! fission
     real(8) :: nu_fission       ! neutron production from fission
+
+    real(8) :: elastic          ! If sab_frac is not 1 or 0, then this value is
+                                !   averaged over bound and non-bound nuclei
     real(8) :: thermal          ! Bound thermal elastic & inelastic scattering
     real(8) :: thermal_elastic  ! Bound thermal elastic scattering
 
@@ -148,7 +158,6 @@ module nuclide_header
 
   type MaterialMacroXS
     real(8) :: total         ! macroscopic total xs
-    real(8) :: elastic       ! macroscopic elastic scattering xs
     real(8) :: absorption    ! macroscopic absorption xs
     real(8) :: fission       ! macroscopic fission xs
     real(8) :: nu_fission    ! macroscopic production xs
@@ -566,21 +575,13 @@ contains
     type(VectorInt) :: MTs
 
     n_temperature = size(this % kTs)
-    allocate(this % sum_xs(n_temperature))
+    allocate(this % xs(n_temperature))
     this % reaction_index(:) = 0
     do i = 1, n_temperature
       ! Allocate and initialize derived cross sections
       n_grid = size(this % grid(i) % energy)
-      allocate(this % sum_xs(i) % total(n_grid))
-      allocate(this % sum_xs(i) % elastic(n_grid))
-      allocate(this % sum_xs(i) % fission(n_grid))
-      allocate(this % sum_xs(i) % nu_fission(n_grid))
-      allocate(this % sum_xs(i) % absorption(n_grid))
-      this % sum_xs(i) % total(:) = ZERO
-      this % sum_xs(i) % elastic(:) = ZERO
-      this % sum_xs(i) % fission(:) = ZERO
-      this % sum_xs(i) % nu_fission(:) = ZERO
-      this % sum_xs(i) % absorption(:) = ZERO
+      allocate(this % xs(i) % value(4,n_grid))
+      this % xs(i) % value(:,:) = ZERO
     end do
 
     i_fission = 0
@@ -607,17 +608,14 @@ contains
           j = rx % xs(t) % threshold
           n = size(rx % xs(t) % value)
 
-          ! Copy elastic
-          if (rx % MT == ELASTIC) this % sum_xs(t) % elastic(:) = rx % xs(t) % value
-
           ! Add contribution to total cross section
-          this % sum_xs(t) % total(j:j+n-1) = this % sum_xs(t) % total(j:j+n-1) + &
-               rx % xs(t) % value
+          this % xs(t) % value(XS_TOTAL,j:j+n-1) = this % xs(t) % &
+               value(XS_TOTAL,j:j+n-1) + rx % xs(t) % value
 
           ! Add contribution to absorption cross section
           if (is_disappearance(rx % MT)) then
-            this % sum_xs(t) % absorption(j:j+n-1) = this % sum_xs(t) % &
-                 absorption(j:j+n-1) + rx % xs(t) % value
+            this % xs(t) % value(XS_ABSORPTION,j:j+n-1) = this % xs(t) % &
+                 value(XS_ABSORPTION,j:j+n-1) + rx % xs(t) % value
           end if
 
           ! Information about fission reactions
@@ -633,12 +631,12 @@ contains
           ! Add contribution to fission cross section
           if (is_fission(rx % MT)) then
             this % fissionable = .true.
-            this % sum_xs(t) % fission(j:j+n-1) = this % sum_xs(t) % &
-                 fission(j:j+n-1) + rx % xs(t) % value
+            this % xs(t) % value(XS_FISSION,j:j+n-1) = this % xs(t) % &
+                 value(XS_FISSION,j:j+n-1) + rx % xs(t) % value
 
             ! Also need to add fission cross sections to absorption
-            this % sum_xs(t) % absorption(j:j+n-1) = this % sum_xs(t) % &
-                 absorption(j:j+n-1) + rx % xs(t) % value
+            this % xs(t) % value(XS_ABSORPTION,j:j+n-1) = this % xs(t) % &
+                 value(XS_ABSORPTION,j:j+n-1) + rx % xs(t) % value
 
             ! If total fission reaction is present, there's no need to store the
             ! reaction cross-section since it was copied to this % fission
@@ -689,12 +687,11 @@ contains
     ! Calculate nu-fission cross section
     do t = 1, n_temperature
       if (this % fissionable) then
-        do i = 1, size(this % sum_xs(t) % fission)
-          this % sum_xs(t) % nu_fission(i) = this % nu(this % grid(t) % energy(i), &
-               EMISSION_TOTAL) * this % sum_xs(t) % fission(i)
+        do i = 1, n_grid
+          this % xs(t) % value(XS_NU_FISSION,i) = &
+               this % nu(this % grid(t) % energy(i), EMISSION_TOTAL) * &
+               this % xs(t) % value(XS_FISSION,i)
         end do
-      else
-        this % sum_xs(t) % nu_fission(:) = ZERO
       end if
     end do
   end subroutine nuclide_create_derived

src/physics.F90

@@ -2,7 +2,7 @@ module physics
 
   use algorithm,              only: binary_search
   use constants
-  use cross_section,          only: elastic_xs_0K
+  use cross_section,          only: elastic_xs_0K, calculate_elastic_xs
   use endf,                   only: reaction_name
   use error,                  only: fatal_error, warning, write_message
   use material_header,        only: Material, materials
@@ -338,6 +338,11 @@ contains
          micro_xs(i_nuclide) % absorption)
     sampled = .false.
 
+    ! Calculate elastic cross section if it wasn't precalculated
+    if (micro_xs(i_nuclide) % elastic == CACHE_INVALID) then
+      call calculate_elastic_xs(i_nuclide)
+    end if
+
     prob = micro_xs(i_nuclide) % elastic - micro_xs(i_nuclide) % thermal
     if (prob > cutoff) then
       ! =======================================================================

src/relaxng/settings.rnc

@@ -3,6 +3,8 @@ element settings {
 
   element confidence_intervals { xsd:boolean }? &
 
+  element create_fission_neutrons { xsd:boolean }? &
+
   element cutoff {
     (element weight { xsd:double } | attribute weight { xsd:double })? &
     (element weight_avg { xsd:double } | attribute weight_avg { xsd:double })?

src/relaxng/settings.rng

@@ -11,6 +11,11 @@
         <data type="boolean"/>
       </element>
     </optional>
+    <optional>
+      <element name="create_fission_neutrons">
+        <data type="boolean"/>
+      </element>
+    </optional>
     <optional>
       <element name="cutoff">
         <interleave>

src/tallies/tally.F90

@@ -4,7 +4,7 @@ module tally
 
   use algorithm,        only: binary_search
   use constants
-  use cross_section,    only: multipole_deriv_eval
+  use cross_section,    only: multipole_deriv_eval, calculate_elastic_xs
   use dict_header,      only: EMPTY
   use error,            only: fatal_error
   use geometry_header
@@ -1017,9 +1017,26 @@ contains
 
         else
           if (i_nuclide > 0) then
+            if (micro_xs(i_nuclide) % elastic == CACHE_INVALID) then
+              call calculate_elastic_xs(i_nuclide)
+            end if
             score = micro_xs(i_nuclide) % elastic * atom_density * flux
           else
-            score = material_xs % elastic * flux
+            score = ZERO
+            if (p % material /= MATERIAL_VOID) then
+              do l = 1, materials(p % material) % n_nuclides
+                ! Get atom density
+                atom_density_ = materials(p % material) % atom_density(l)
+
+                ! Get index in nuclides array
+                i_nuc = materials(p % material) % nuclide(l)
+                if (micro_xs(i_nuc) % elastic == CACHE_INVALID) then
+                  call calculate_elastic_xs(i_nuc)
+                end if
+
+                score = score + micro_xs(i_nuc) % elastic * atom_density_ * flux
+              end do
+            end if
           end if
         end if
 

src/tracking.F90

@@ -2,7 +2,7 @@ module tracking
 
   use constants
   use cross_section,      only: calculate_xs
-  use error,              only: fatal_error, warning, write_message
+  use error,              only: warning, write_message
   use geometry_header,    only: cells
   use geometry,           only: find_cell, distance_to_boundary, cross_lattice, &
                                 check_cell_overlap
@@ -85,7 +85,9 @@ contains
       if (p % coord(p % n_coord) % cell == NONE) then
         call find_cell(p, found_cell)
         if (.not. found_cell) then
-          call fatal_error("Could not locate particle " // trim(to_str(p % id)))
+          call p % mark_as_lost("Could not find the cell containing" &
+                     // " particle " // trim(to_str(p %id)))
+          return
         end if
 
         ! set birth cell attribute

tests/test_mg_convert/test_mg_convert.py

@@ -139,13 +139,10 @@ class MGXSTestHarness(PyAPITestHarness):
 
             if self._opts.mpi_exec is not None:
                 mpi_args = [self._opts.mpi_exec, '-n', self._opts.mpi_np]
-                returncode = openmc.run(openmc_exec=self._opts.exe,
-                                        mpi_args=mpi_args)
+                openmc.run(openmc_exec=self._opts.exe, mpi_args=mpi_args)
 
             else:
-                returncode = openmc.run(openmc_exec=self._opts.exe)
-
-            assert returncode == 0, 'OpenMC did not exit successfully.'
+                openmc.run(openmc_exec=self._opts.exe)
 
             sp = openmc.StatePoint('statepoint.' + str(batches) + '.h5')
 

tests/test_mgxs_library_ce_to_mg/test_mgxs_library_ce_to_mg.py

@@ -36,13 +36,9 @@ class MGXSTestHarness(PyAPITestHarness):
         # Initial run
         if self._opts.mpi_exec is not None:
             mpi_args = [self._opts.mpi_exec, '-n', self._opts.mpi_np]
-            returncode = openmc.run(openmc_exec=self._opts.exe,
-                                    mpi_args=mpi_args)
+            openmc.run(openmc_exec=self._opts.exe, mpi_args=mpi_args)
         else:
-            returncode = openmc.run(openmc_exec=self._opts.exe)
-
-        assert returncode == 0, 'CE OpenMC calculation did not exit' \
-                                'successfully.'
+            openmc.run(openmc_exec=self._opts.exe)
 
         # Build MG Inputs
         # Get data needed to execute Library calculations.
@@ -73,10 +69,9 @@ class MGXSTestHarness(PyAPITestHarness):
         # Re-run MG mode.
         if self._opts.mpi_exec is not None:
             mpi_args = [self._opts.mpi_exec, '-n', self._opts.mpi_np]
-            returncode = openmc.run(openmc_exec=self._opts.exe,
-                                    mpi_args=mpi_args)
+            openmc.run(openmc_exec=self._opts.exe, mpi_args=mpi_args)
         else:
-            returncode = openmc.run(openmc_exec=self._opts.exe)
+            openmc.run(openmc_exec=self._opts.exe)
 
     def _cleanup(self):
         super(MGXSTestHarness, self)._cleanup()

tests/test_plot/test_plot.py

@@ -19,8 +19,7 @@ class PlotTestHarness(TestHarness):
         self._plot_names = plot_names
 
     def _run_openmc(self):
-        returncode = openmc.plot_geometry(openmc_exec=self._opts.exe)
-        assert returncode == 0, 'OpenMC did not exit successfully.'
+        openmc.plot_geometry(openmc_exec=self._opts.exe)
 
     def _test_output_created(self):
         """Make sure *.ppm has been created."""

tests/test_statepoint_restart/test_statepoint_restart.py

@@ -50,14 +50,10 @@ class StatepointRestartTestHarness(TestHarness):
         # Run OpenMC
         if self._opts.mpi_exec is not None:
             mpi_args = [self._opts.mpi_exec, '-n', self._opts.mpi_np]
-            returncode = openmc.run(restart_file=statepoint,
-                                    openmc_exec=self._opts.exe,
-                                    mpi_args=mpi_args)
+            openmc.run(restart_file=statepoint, openmc_exec=self._opts.exe,
+                       mpi_args=mpi_args)
         else:
-            returncode = openmc.run(openmc_exec=self._opts.exe,
-                                    restart_file=statepoint)
-
-        assert returncode == 0, 'OpenMC did not exit successfully.'
+            openmc.run(openmc_exec=self._opts.exe, restart_file=statepoint)
 
 
 if __name__ == '__main__':

tests/testing_harness.py

@@ -62,14 +62,10 @@ class TestHarness(object):
 
     def _run_openmc(self):
         if self._opts.mpi_exec is not None:
-            returncode = openmc.run(
-                openmc_exec=self._opts.exe,
-                mpi_args=[self._opts.mpi_exec, '-n', self._opts.mpi_np])
-
+            openmc.run(openmc_exec=self._opts.exe,
+                       mpi_args=[self._opts.mpi_exec, '-n', self._opts.mpi_np])
         else:
-            returncode = openmc.run(openmc_exec=self._opts.exe)
-
-        assert returncode == 0, 'OpenMC did not exit successfully.'
+            openmc.run(openmc_exec=self._opts.exe)
 
     def _test_output_created(self):
         """Make sure statepoint.* and tallies.out have been created."""
@@ -189,13 +185,11 @@ class ParticleRestartTestHarness(TestHarness):
             args['mpi_args'] = [self._opts.mpi_exec, '-n', self._opts.mpi_np]
 
         # Initial run
-        returncode = openmc.run(**args)
-        assert returncode == 0, 'OpenMC did not exit successfully.'
+        openmc.run(**args)
 
         # Run particle restart
         args.update({'restart_file': self._sp_name})
-        returncode = openmc.run(**args)
-        assert returncode == 0, 'OpenMC did not exit successfully.'
+        openmc.run(**args)
 
     def _test_output_created(self):
         """Make sure the restart file has been created."""