Fixed failing test: not enough neutrons simulated so many cross sections were zero. Made OpenMC properly deal with that case and then added more neutrons to the test to make it a bit more useful

src/mgxs_header.F90

@@ -1485,8 +1485,13 @@ module mgxs_header
                    nuc % scatter % energy(gin) % data(gout)
               mult_num(gout, gin) = mult_num(gout, gin) + atom_density * &
                    nuscatt
-              mult_denom(gout, gin) = mult_denom(gout,gin) + atom_density * &
-                   nuscatt / nuc % scatter % mult(gin) % data(gout)
+              if (nuc % scatter % mult(gin) % data(gout) > ZERO) then
+                mult_denom(gout, gin) = mult_denom(gout,gin) + atom_density * &
+                     nuscatt / nuc % scatter % mult(gin) % data(gout)
+              else
+                ! Avoid division by zero
+                mult_denom(gout, gin) = mult_denom(gout,gin) + atom_density
+              end if
             end do
           end do
 
@@ -1722,10 +1727,16 @@ module mgxs_header
                        nuc % scatter(iazi, ipol) % obj % energy(gin) % data(gout)
                   mult_num(gout, gin, iazi, ipol) = mult_num(gout, gin, iazi, ipol) + &
                        atom_density * nuscatt
-                  mult_denom(gout, gin, iazi, ipol) = &
-                       mult_denom(gout, gin, iazi, ipol) + &
-                       atom_density * nuscatt / &
-                       nuc % scatter(iazi, ipol) % obj % mult(gin) % data(gout)
+                  if (nuc % scatter(iazi, ipol) % obj % mult(gin) % data(gout) > ZERO) then
+                    mult_denom(gout, gin, iazi, ipol) = &
+                         mult_denom(gout, gin, iazi, ipol) + &
+                         atom_density * nuscatt / &
+                         nuc % scatter(iazi, ipol) % obj % mult(gin) % data(gout)
+                  else
+                    ! Avoid division by zero
+                    mult_denom(gout, gin, iazi, ipol) = &
+                         mult_denom(gout,gin, iazi, ipol) + atom_density
+                  end if
                 end do
               end do
             end do

tests/run_tests.py

@@ -474,7 +474,6 @@ for key in iter(tests):
         logfilename = os.path.splitext(logfilename)[0]
         logfilename = logfilename + '_{0}.log'.format(test.name)
         shutil.copy(logfile[0], logfilename)
-        with open(logfilename) as fh: print(fh.read())
 
     # For coverage builds, use lcov to generate HTML output
     if test.coverage:

tests/test_mgxs_library_ce_to_mg/inputs_true.dat

@@ -1 +1 @@
-15355a90181bc3a8ba70bcc9a89beff2c240dc75abbf26c3e3b6a940c4ec2028b238422ac26af08863c24ce6fc16d48d249f17cd0bce53df0141138deccfc81a
+f6442195628d3e6acd714d1ac123310a8c463ce6e76de2149783e4d9f2485752b53155f78bd9ae5e886b5f4717ef7c66b71959344051ea7f53b79148d59fe609

tests/test_mgxs_library_ce_to_mg/results_true.dat

@@ -1,2 +1,2 @@
 k-combined:
-1.017325E+00 3.827758E-02
+1.006931E+00 3.262911E-03

tests/test_mgxs_library_ce_to_mg/test_mgxs_library_ce_to_mg.py

@@ -13,12 +13,19 @@ import openmc.mgxs
 class MGXSTestHarness(PyAPITestHarness):
     def _build_inputs(self):
 
-        # The openmc.mgxs module needs a summary.h5 file
-        self._input_set.settings.output = {'summary': True}
-
         # Generate inputs using parent class routine
         super(MGXSTestHarness, self)._build_inputs()
 
+        # The openmc.mgxs module needs a summary.h5 file
+        self._input_set.settings.output = {'summary': True}
+        # Use a larger history count to get some scores in every material
+        self._input_set.settings.batches = 50
+        self._input_set.settings.inactive = 10
+        self._input_set.settings.particles = 1000
+        self._sp_name = './statepoint.50.h5'
+        # Rewrite file
+        self._input_set.settings.export_to_xml()
+
         # Initialize a two-group structure
         energy_groups = openmc.mgxs.EnergyGroups(group_edges=[0, 0.625e-6, 20.])