diff --git a/src/utils/openmc/statepoint.py b/src/utils/openmc/statepoint.py
index 9ff38c2b00..7c4f90ae38 100644
--- a/src/utils/openmc/statepoint.py
+++ b/src/utils/openmc/statepoint.py
@@ -654,14 +654,14 @@ class StatePoint(object):
 
         for tally_id, tally in self._tallies.items():
 
-            nuclides = copy.deepcopy(tally._nuclides)
+            nuclide_zaids = copy.deepcopy(tally._nuclides)
 
-            for nuclide_index in nuclides:
-                tally.remove_nuclide(nuclide_index)
-                if nuclide_index == -1:
+            for nuclide_zaid in nuclide_zaids:
+                tally.remove_nuclide(nuclide_zaid)
+                if nuclide_zaid == -1:
                     tally.add_nuclide(openmc.Nuclide('total'))
                 else:
-                    tally.add_nuclide(summary.nuclides[nuclide_index])
+                    tally.add_nuclide(summary.nuclides[nuclide_zaid])
 
             for filter in tally._filters:
 
@@ -730,4 +730,4 @@ class StatePoint(object):
         if self._hdf5:
             return str(self._f[path].value)
         else:
-            return str(self._get_data(n, 's', 1)[0])
\ No newline at end of file
+            return str(self._get_data(n, 's', 1)[0])
diff --git a/src/utils/openmc/summary.py b/src/utils/openmc/summary.py
index 9bfa50711d..81e0b3bf5d 100644
--- a/src/utils/openmc/summary.py
+++ b/src/utils/openmc/summary.py
@@ -82,12 +82,12 @@ class Summary(object):
             # Read the Nuclide's cross-section identifier (e.g., '70c')
             xs = alias.split('.')[1]
 
-            # Initialize this Nuclide and add it to the global dictionary of Nuclides
+            # Initialize this Nuclide and add to global dictionary of Nuclides
             if 'nat' in name:
-                self.nuclides[index] = openmc.Element(name=name, xs=xs)
+                self.nuclides[zaid] = openmc.Element(name=name, xs=xs)
             else:
-                self.nuclides[index] = openmc.Nuclide(name=name, xs=xs)
-                self.nuclides[index].set_zaid(zaid)
+                self.nuclides[zaid] = openmc.Nuclide(name=name, xs=xs)
+                self.nuclides[zaid].set_zaid(zaid)
 
 
     def _read_materials(self):