Approximate multigroup velocity

include/openmc/mgxs_interface.h

@@ -61,6 +61,7 @@ class MgxsInterface {
   vector<double> energy_bin_avg_;
   vector<double> rev_energy_bins_;
   vector<vector<double>> nuc_temps_; // all available temperatures
+  vector<double> void_velocities_;   // velocity of particles in void regions
 };
 
 namespace data {

openmc/examples.py

@@ -1061,7 +1061,7 @@ def fill_cube(N, n_1, n_2, fill_1, fill_2, fill_3):
 
     void_sigma_a = 4.0e-6
     void_sigma_s = 3.0e-4
-    void_mat_data = openmc.XSdata('void', groups)
+    void_mat_data = openmc.XSdata('approx void', groups)
     void_mat_data.order = 0
     void_mat_data.set_total([void_sigma_a + void_sigma_s])
     void_mat_data.set_absorption([void_sigma_a])
@@ -1097,15 +1097,15 @@ def fill_cube(N, n_1, n_2, fill_1, fill_2, fill_3):
 
     # Instantiate some Macroscopic Data
     source_data = openmc.Macroscopic('source')
-    void_data = openmc.Macroscopic('void')
+    void_data = openmc.Macroscopic('approx void')
     absorber_data = openmc.Macroscopic('absorber')
 
     # Instantiate some Materials and register the appropriate Macroscopic objects
     source_mat = openmc.Material(name='source')
     source_mat.set_density('macro', 1.0)
     source_mat.add_macroscopic(source_data)
 
-    void_mat = openmc.Material(name='void')
+    void_mat = openmc.Material(name='approx void')
     void_mat.set_density('macro', 1.0)
     void_mat.add_macroscopic(void_data)
 

openmc/mgxs_library.py

@@ -11,7 +11,7 @@
 import openmc.mgxs
 from openmc.mgxs import SCATTER_TABULAR, SCATTER_LEGENDRE, SCATTER_HISTOGRAM
 from .checkvalue import check_type, check_value, check_greater_than, \
-    check_iterable_type, check_less_than, check_filetype_version, PathLike
+    check_iterable_type, check_length, check_less_than, check_filetype_version, PathLike
 
 ROOM_TEMPERATURE_KELVIN = 294.0
 
@@ -177,7 +177,9 @@ class XSdata:
     def __init__(self, name, energy_groups, temperatures=[ROOM_TEMPERATURE_KELVIN],
                  representation=REPRESENTATION_ISOTROPIC, num_delayed_groups=0):
 
-        # Initialize class attributes
+        self._is_void = False
+
+        #Initialize class attributes
         self.name = name
         self.energy_groups = energy_groups
         self.num_delayed_groups = num_delayed_groups
@@ -260,6 +262,9 @@ def name(self):
     def name(self, name):
 
         check_type('name for XSdata', name, str)
+        if name == 'void':
+          self._is_void = True
+
         self._name = name
 
     @property
@@ -322,6 +327,8 @@ def temperatures(self):
 
     @temperatures.setter
     def temperatures(self, temperatures):
+        if self._is_void:
+          check_length('temperatures', temperatures, 1, 1)
 
         check_iterable_type('temperatures', temperatures, Real)
         self._temperatures = np.array(temperatures)
@@ -481,6 +488,8 @@ def add_temperature(self, temperature):
             Temperature (in units of Kelvin) of the provided dataset.
 
         """
+        if self._is_void:
+            raise TypeError('Cannot add temperatures to a void xs')
 
         check_type('temperature', temperature, Real)
 
@@ -532,6 +541,8 @@ def set_total(self, total, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_total_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set total xs in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G]"]]
@@ -561,6 +572,8 @@ def set_absorption(self, absorption, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_absorption_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set absorption xs in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G]"]]
@@ -590,6 +603,8 @@ def set_fission(self, fission, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_fission_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set fission xs in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G]"]]
@@ -621,6 +636,8 @@ def set_kappa_fission(self, kappa_fission, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_kappa_fission_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set kappa-fission xs in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G]"]]
@@ -652,6 +669,8 @@ def set_chi(self, chi, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_chi_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set chi in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G']"]]
@@ -681,6 +700,8 @@ def set_chi_prompt(self, chi_prompt, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_chi_prompt_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set chi-prompt in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G']"]]
@@ -710,6 +731,8 @@ def set_chi_delayed(self, chi_delayed, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_chi_delayed_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set chi-delayed in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G']"], self.xs_shapes["[DG][G']"]]
@@ -741,6 +764,8 @@ def set_beta(self, beta, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_beta_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set beta in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[DG]"], self.xs_shapes["[DG][G]"]]
@@ -770,6 +795,8 @@ def set_decay_rate(self, decay_rate, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_decay_rate_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set decay rate in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[DG]"]]
@@ -799,6 +826,8 @@ def set_scatter_matrix(self, scatter, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_scatter_matrix_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set scatter matrix in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G][G'][Order]"]]
@@ -830,6 +859,8 @@ def set_multiplicity_matrix(self, multiplicity, temperature=ROOM_TEMPERATURE_KEL
         openmc.mgxs_library.set_multiplicity_matrix_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set multiplicity matrix in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G][G']"]]
@@ -861,6 +892,8 @@ def set_nu_fission(self, nu_fission, temperature=ROOM_TEMPERATURE_KELVIN):
         openmc.mgxs_library.set_nu_fission_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set nu-fission in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G]"], self.xs_shapes["[G][G']"]]
@@ -893,6 +926,8 @@ def set_prompt_nu_fission(self, prompt_nu_fission, temperature=ROOM_TEMPERATURE_
         openmc.mgxs_library.set_prompt_nu_fission_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set prompt nu-fission in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[G]"], self.xs_shapes["[G][G']"]]
@@ -925,6 +960,8 @@ def set_delayed_nu_fission(self, delayed_nu_fission, temperature=ROOM_TEMPERATUR
         openmc.mgxs_library.set_delayed_nu_fission_mgxs()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set delayed nu-fission in a void')
 
         # Get the accepted shapes for this xs
         shapes = [self.xs_shapes["[DG][G]"], self.xs_shapes["[DG][G][G']"]]
@@ -996,6 +1033,8 @@ def set_total_mgxs(self, total, temperature=ROOM_TEMPERATURE_KELVIN, nuclide='to
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set total xs in a void')
 
         check_type('total', total, (openmc.mgxs.TotalXS,
                                     openmc.mgxs.TransportXS))
@@ -1036,6 +1075,8 @@ def set_absorption_mgxs(self, absorption, temperature=ROOM_TEMPERATURE_KELVIN,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set absorption xs in a void')        
 
         check_type('absorption', absorption, openmc.mgxs.AbsorptionXS)
         check_value('energy_groups', absorption.energy_groups,
@@ -1078,6 +1119,8 @@ def set_fission_mgxs(self, fission, temperature=ROOM_TEMPERATURE_KELVIN, nuclide
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set fission in a void')        
 
         check_type('fission', fission, openmc.mgxs.FissionXS)
         check_value('energy_groups', fission.energy_groups,
@@ -1120,6 +1163,8 @@ def set_nu_fission_mgxs(self, nu_fission, temperature=ROOM_TEMPERATURE_KELVIN,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set nu-fission in a void')        
 
         check_type('nu_fission', nu_fission, (openmc.mgxs.FissionXS,
                                               openmc.mgxs.NuFissionMatrixXS))
@@ -1171,6 +1216,8 @@ def set_prompt_nu_fission_mgxs(self, prompt_nu_fission, temperature=ROOM_TEMPERA
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set prompt nu-fission in a void')        
 
         check_type('prompt_nu_fission', prompt_nu_fission,
                    (openmc.mgxs.FissionXS, openmc.mgxs.NuFissionMatrixXS))
@@ -1218,6 +1265,8 @@ def set_delayed_nu_fission_mgxs(self, delayed_nu_fission, temperature=ROOM_TEMPE
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set delayed nu-fission in a void')        
 
         check_type('delayed_nu_fission', delayed_nu_fission,
                    (openmc.mgxs.DelayedNuFissionXS,
@@ -1267,6 +1316,8 @@ def set_kappa_fission_mgxs(self, k_fission, temperature=ROOM_TEMPERATURE_KELVIN,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set kappa-fission in a void')         
 
         check_type('kappa_fission', k_fission, openmc.mgxs.KappaFissionXS)
         check_value('energy_groups', k_fission.energy_groups,
@@ -1308,6 +1359,8 @@ def set_chi_mgxs(self, chi, temperature=ROOM_TEMPERATURE_KELVIN, nuclide='total'
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set chi in a void')         
 
         check_type('chi', chi, openmc.mgxs.Chi)
         check_value('energy_groups', chi.energy_groups, [self.energy_groups])
@@ -1346,6 +1399,8 @@ def set_chi_prompt_mgxs(self, chi_prompt, temperature=ROOM_TEMPERATURE_KELVIN,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set prompt chi in a void')        
 
         check_type('chi_prompt', chi_prompt, openmc.mgxs.Chi)
         check_value('prompt', chi_prompt.prompt, [True])
@@ -1388,6 +1443,8 @@ def set_chi_delayed_mgxs(self, chi_delayed, temperature=ROOM_TEMPERATURE_KELVIN,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set delayed chi in a void')        
 
         check_type('chi_delayed', chi_delayed, openmc.mgxs.ChiDelayed)
         check_value('energy_groups', chi_delayed.energy_groups,
@@ -1431,6 +1488,8 @@ def set_beta_mgxs(self, beta, temperature=ROOM_TEMPERATURE_KELVIN,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set beta in a void')        
 
         check_type('beta', beta, openmc.mgxs.Beta)
         check_value('num_delayed_groups', beta.num_delayed_groups,
@@ -1471,6 +1530,8 @@ def set_decay_rate_mgxs(self, decay_rate, temperature=ROOM_TEMPERATURE_KELVIN,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set decay rate in a void')        
 
         check_type('decay_rate', decay_rate, openmc.mgxs.DecayRate)
         check_value('num_delayed_groups', decay_rate.num_delayed_groups,
@@ -1516,6 +1577,8 @@ def set_scatter_matrix_mgxs(self, scatter, temperature=ROOM_TEMPERATURE_KELVIN,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set scatter matrix in a void')        
 
         check_type('scatter', scatter, openmc.mgxs.ScatterMatrixXS)
         check_value('energy_groups', scatter.energy_groups,
@@ -1604,6 +1667,8 @@ def set_multiplicity_matrix_mgxs(self, nuscatter, scatter=None,
         openmc.mgxs.Library.get_xsdata()
 
         """
+        if self._is_void:
+            raise TypeError('Cannot set multiplicity matrix in a void')                
 
         check_type('nuscatter', nuscatter, (openmc.mgxs.ScatterMatrixXS,
                                             openmc.mgxs.MultiplicityMatrixXS))
@@ -1992,6 +2057,15 @@ def to_hdf5(self, file):
 
             xs_grp = grp.create_group(str(int(np.round(temperature))) + "K")
 
+            # Add the kinetics data
+            if self._inverse_velocity[i] is not None:
+                xs_grp.create_dataset("inverse-velocity",
+                                      data=self._inverse_velocity[i])
+            elif self._is_void:
+                raise TypeError('Void mgxs must have inverse-velocity data.')
+
+            if self._is_void: continue
+
             if self._total[i] is None:
                 raise ValueError('total data must be provided when writing '
                                  'the HDF5 library')
@@ -2141,10 +2215,6 @@ def to_hdf5(self, file):
                 scatt_grp.create_dataset("g_min", data=g_out_bounds[:, :, :, 0])
                 scatt_grp.create_dataset("g_max", data=g_out_bounds[:, :, :, 1])
 
-            # Add the kinetics data
-            if self._inverse_velocity[i] is not None:
-                xs_grp.create_dataset("inverse-velocity",
-                                      data=self._inverse_velocity[i])
 
     @classmethod
     def from_hdf5(cls, group, name, energy_groups, num_delayed_groups):

src/cell.cpp

@@ -20,6 +20,7 @@
 #include "openmc/hdf5_interface.h"
 #include "openmc/lattice.h"
 #include "openmc/material.h"
+#include "openmc/mgxs_interface.h"
 #include "openmc/nuclide.h"
 #include "openmc/settings.h"
 #include "openmc/xml_interface.h"
@@ -397,6 +398,10 @@ CSGCell::CSGCell(pugi::xml_node cell_node)
       for (std::string mat : mats) {
         if (mat.compare("void") == 0) {
           material_.push_back(MATERIAL_VOID);
+          if (!settings::run_CE && data::mg.void_velocities_.empty())
+            warning("Void inverse-velocity data is not available in the "
+                    "multi-group nuclear data library. "
+                    "Time related calculation results might be wrong!");
         } else {
           material_.push_back(std::stoi(mat));
         }