address review comments

openmc/deplete/integrator/cecm.py

@@ -47,7 +47,7 @@ def cecm(operator, timesteps, power=None, power_density=None, print_out=True):
     """
     if power is None:
         if power_density is None:
-            raise RuntimeError(
+            raise ValueError(
                 "Neither power nor power density was specified.")
         if not isinstance(power_density, Iterable):
             power = power_density*operator.heavy_metal

openmc/deplete/integrator/predictor.py

@@ -43,7 +43,7 @@ def predictor(operator, timesteps, power=None, power_density=None,
     """
     if power is None:
         if power_density is None:
-            raise RuntimeError(
+            raise ValueError(
                 "Neither power nor power density was specified.")
         if not isinstance(power_density, Iterable):
             power = power_density*operator.heavy_metal

openmc/deplete/operator.py

@@ -70,6 +70,8 @@ class Operator(TransportOperator):
         Results from a previous depletion calculation. If this argument is
         specified, the depletion calculation will start from the latest state
         in the previous results.
+    diff_burnable_mats : bool, optional
+        Whether to differentiate burnable materials with multiple instances
 
     Attributes
     ----------
@@ -102,13 +104,17 @@ class Operator(TransportOperator):
         All burnable material IDs being managed by a single process
     prev_res : ResultsList
         Results from a previous depletion calculation
+    diff_burnable_mats : bool
+        Whether to differentiate burnable materials with multiple instances
 
     """
-    def __init__(self, geometry, settings, chain_file=None, prev_results=None):
+    def __init__(self, geometry, settings, chain_file=None, prev_results=None,
+                 diff_burnable_mats=True):
         super().__init__(chain_file)
         self.round_number = False
         self.settings = settings
         self.geometry = geometry
+        self.diff_burnable_mats = diff_burnable_mats
 
         if prev_results != None:
             # Reload volumes into geometry
@@ -221,8 +227,9 @@ class Operator(TransportOperator):
 
         """
 
-        # Automatically distribute burnable materials
-        self._differentiate_burnable_mats()
+        if self.diff_burnable_mats:
+            # Automatically distribute burnable materials
+            self._differentiate_burnable_mats()
 
         burnable_mats = set()
         model_nuclides = set()

openmc/material.py

@@ -747,6 +747,7 @@ class Material(IDManagerMixin):
             raise ValueError("Volume must be set in order to determine mass.")
         return self.volume*self.get_mass_density(nuclide)
 
+    @property
     def get_heavy_metal_mass(self):
         """Return mass of heavy metal nuclides.
 

src/input_xml.F90

@@ -2258,7 +2258,7 @@ contains
           call write_message("Maximum neutron transport energy: " // &
                trim(to_str(energy_max(NEUTRON))) // " eV for " // &
                trim(adjustl(nuclides(i) % name)), 7)
-          if (master .and. energy_max(NEUTRON) < 20.E6) call warning("Maximum &
+          if (master .and. energy_max(NEUTRON) < 20.e6) call warning("Maximum &
                &neutron energy is below 20 MeV. This may bias the results.")
           exit
         end if