diff --git a/docs/source/io_formats/mgxs_library.rst b/docs/source/io_formats/mgxs_library.rst
index e9b59a20f..9262a234e 100644
--- a/docs/source/io_formats/mgxs_library.rst
+++ b/docs/source/io_formats/mgxs_library.rst
@@ -6,7 +6,7 @@ Multi-Group Cross Section Library Format
 
 OpenMC can be run in continuous-energy mode or multi-group mode, provided the
 nuclear data is available.  In continuous-energy mode, the
-``cross_sections.xml`` file contains necessary meta-data for each data set,
+``cross_sections.xml`` file contains necessary meta-data for each dataset,
 including the name and a file system location where the complete library
 can be found.  In multi-group mode, the multi-group meta-data and the
 nuclear data itself is contained within an ``mgxs.h5``.  This portion of
@@ -89,19 +89,19 @@ Temperature-dependent data, provided for temperature <TTT>K.
              cross section.
              This is a 1-D vector if `representation` is "isotropic", or a 3-D
              vector if `representation` is "angle" with dimensions of
-             [groups, azimuthal, polar].  This is only required if the data set
+             [groups, azimuthal, polar].  This is only required if the dataset
              is fissionable and fission-tallies are expected to be used.
            - **kappa-fission** (*double[]* or *double[][][]*) -- Kappa-Fission
              (energy-release from fission) cross section.
              This is a 1-D vector if `representation` is "isotropic", or a 3-D
              vector if `representation` is "angle" with dimensions of
-             [groups, azimuthal, polar].  This is only required if the data set
+             [groups, azimuthal, polar].  This is only required if the dataset
              is fissionable and fission-tallies are expected to be used.
            - **chi** (*double[]* or *double[][][]*) -- Fission neutron energy
              spectra.
              This is a 1-D vector if `representation` is "isotropic", or a 3-D
              vector if `representation` is "angle" with dimensions of
-             [groups, azimuthal, polar].  This is only required if the data set
+             [groups, azimuthal, polar].  This is only required if the dataset
              is fissionable and fission-tallies are expected to be used.
            - **nu-fission** (*double[]* to *double[][][][]*) -- Nu-Fission
              cross section.
diff --git a/openmc/mgxs/library.py b/openmc/mgxs/library.py
index c4515c969..5535f8485 100644
--- a/openmc/mgxs/library.py
+++ b/openmc/mgxs/library.py
@@ -186,14 +186,14 @@ class Library(object):
 
     @property
     def domains(self):
-        if self._domains == 'all':
-            if self.domain_type == 'material':
+        if self._domains is 'all':
+            if self.domain_type is 'material':
                 return self.openmc_geometry.get_all_materials()
             elif self.domain_type in ['cell', 'distribcell']:
                 return self.openmc_geometry.get_all_material_cells()
-            elif self.domain_type == 'universe':
+            elif self.domain_type is 'universe':
                 return self.openmc_geometry.get_all_universes()
-            elif self.domain_type == 'mesh':
+            elif self.domain_type is 'mesh':
                 raise ValueError('Unable to get domains for Mesh domain type')
             else:
                 raise ValueError('Unable to get domains without a domain type')
@@ -265,7 +265,7 @@ class Library(object):
     @mgxs_types.setter
     def mgxs_types(self, mgxs_types):
         all_mgxs_types = openmc.mgxs.MGXS_TYPES + openmc.mgxs.MDGXS_TYPES
-        if mgxs_types == 'all':
+        if mgxs_types is 'all':
             self._mgxs_types = all_mgxs_types
         else:
             cv.check_iterable_type('mgxs_types', mgxs_types, basestring)
@@ -277,7 +277,7 @@ class Library(object):
     def by_nuclide(self, by_nuclide):
         cv.check_type('by_nuclide', by_nuclide, bool)
 
-        if by_nuclide == True and self.domain_type == 'mesh':
+        if by_nuclide == True and self.domain_type is 'mesh':
             raise ValueError('Unable to create MGXS library by nuclide with '
                              'mesh domain')
 
@@ -287,7 +287,7 @@ class Library(object):
     def domain_type(self, domain_type):
         cv.check_value('domain type', domain_type, openmc.mgxs.DOMAIN_TYPES)
 
-        if self.by_nuclide == True and domain_type == 'mesh':
+        if self.by_nuclide == True and domain_type is 'mesh':
             raise ValueError('Unable to create MGXS library by nuclide with '
                              'mesh domain')
 
@@ -297,21 +297,21 @@ class Library(object):
     def domains(self, domains):
 
         # Use all materials, cells or universes in the geometry as domains
-        if domains == 'all':
+        if domains is 'all':
             self._domains = domains
 
         # User specified a list of material, cell or universe domains
         else:
-            if self.domain_type == 'material':
+            if self.domain_type is 'material':
                 cv.check_iterable_type('domain', domains, openmc.Material)
                 all_domains = self.openmc_geometry.get_all_materials()
             elif self.domain_type in ['cell', 'distribcell']:
                 cv.check_iterable_type('domain', domains, openmc.Cell)
                 all_domains = self.openmc_geometry.get_all_material_cells()
-            elif self.domain_type == 'universe':
+            elif self.domain_type is 'universe':
                 cv.check_iterable_type('domain', domains, openmc.Universe)
                 all_domains = self.openmc_geometry.get_all_universes()
-            elif self.domain_type == 'mesh':
+            elif self.domain_type is 'mesh':
                 cv.check_iterable_type('domain', domains, openmc.Mesh)
 
                 # The mesh and geometry are independent, so set all_domains
@@ -355,7 +355,7 @@ class Library(object):
     def correction(self, correction):
         cv.check_value('correction', correction, ('P0', None))
 
-        if correction == 'P0' and self.legendre_order > 0:
+        if correction is 'P0' and self.legendre_order > 0:
             warn('The P0 correction will be ignored since the scattering '
                  'order "{}" is greater than zero'.format(self.legendre_order))
 
@@ -367,7 +367,7 @@ class Library(object):
         cv.check_greater_than('legendre_order', legendre_order, 0, equality=True)
         cv.check_less_than('legendre_order', legendre_order, 10, equality=True)
 
-        if self.correction == 'P0' and legendre_order > 0:
+        if self.correction is 'P0' and legendre_order > 0:
             msg = 'The P0 correction will be ignored since the scattering ' \
                   'order {} is greater than zero'.format(self.legendre_order)
             warn(msg, RuntimeWarning)
@@ -505,7 +505,7 @@ class Library(object):
         self._openmc_geometry = statepoint.summary.openmc_geometry
         self._nuclides = statepoint.summary.nuclides
 
-        if statepoint.run_mode == 'k-eigenvalue':
+        if statepoint.run_mode is 'k-eigenvalue':
             self._keff = statepoint.k_combined[0]
 
         # Load tallies for each MGXS for each domain and mgxs type
@@ -543,13 +543,13 @@ class Library(object):
 
         """
 
-        if self.domain_type == 'material':
+        if self.domain_type is 'material':
             cv.check_type('domain', domain, (openmc.Material, Integral))
-        elif self.domain_type == 'cell' or self.domain_type == 'distribcell':
+        elif self.domain_type is 'cell' or self.domain_type is 'distribcell':
             cv.check_type('domain', domain, (openmc.Cell, Integral))
-        elif self.domain_type == 'universe':
+        elif self.domain_type is 'universe':
             cv.check_type('domain', domain, (openmc.Universe, Integral))
-        elif self.domain_type == 'mesh':
+        elif self.domain_type is 'mesh':
             cv.check_type('domain', domain, (openmc.Mesh, Integral))
 
         # Check that requested domain is included in library
@@ -662,7 +662,7 @@ class Library(object):
         # Clone this Library to initialize the subdomain-averaged version
         subdomain_avg_library = copy.deepcopy(self)
 
-        if subdomain_avg_library.domain_type == 'distribcell':
+        if subdomain_avg_library.domain_type is 'distribcell':
             subdomain_avg_library.domain_type = 'cell'
         else:
             return subdomain_avg_library
@@ -671,7 +671,7 @@ class Library(object):
         for domain in self.domains:
             for mgxs_type in self.mgxs_types:
                 mgxs = subdomain_avg_library.get_mgxs(domain, mgxs_type)
-                if mgxs.domain_type == 'distribcell':
+                if mgxs.domain_type is 'distribcell':
                     avg_mgxs = mgxs.get_subdomain_avg_xs()
                     subdomain_avg_library.all_mgxs[domain.id][mgxs_type] = avg_mgxs
 
@@ -751,7 +751,7 @@ class Library(object):
             for mgxs_type in self.mgxs_types:
                 mgxs = self.all_mgxs[domain.id][mgxs_type]
 
-                if subdomains == 'avg':
+                if subdomains is 'avg':
                     mgxs = mgxs.get_subdomain_avg_xs()
 
                 mgxs.build_hdf5_store(filename, directory, xs_type=xs_type,
@@ -824,8 +824,9 @@ class Library(object):
     def get_xsdata(self, domain, xsdata_name, nuclide='total', xs_type='macro',
                    order=None, subdomain=None):
         """Generates an openmc.XSdata object describing a multi-group cross section
-        data set for eventual combination in to an openmc.MGXSLibrary object
-        (i.e., the library).  Note that this method does not build an XSdata
+        dataset for writing to an openmc.MGXSLibrary object.
+
+        Note that this method does not build an XSdata
         object with nested temperature tables.  The temperature of each
         XSdata object will be left at the default value of 300K.
 
@@ -856,7 +857,7 @@ class Library(object):
         Returns
         -------
         xsdata : openmc.XSdata
-            Multi-Group Cross Section data set object.
+            Multi-Group Cross Section dataset object.
 
         Raises
         ------
@@ -920,7 +921,7 @@ class Library(object):
             subdomain = [subdomain]
 
         # Now get xs data itself
-        if 'nu-transport' in self.mgxs_types and self.correction == 'P0':
+        if 'nu-transport' in self.mgxs_types and self.correction is 'P0':
             mymgxs = self.get_mgxs(domain, 'nu-transport')
             xsdata.set_total_mgxs(mymgxs, xs_type=xs_type, nuclide=[nuclide],
                                   subdomains=subdomain)
@@ -995,7 +996,7 @@ class Library(object):
                 # scattering multiplication (nu-scatter) must be
                 # accounted for approximately by using an adjusted
                 # absorption cross section.
-                if 'total' in self.mgxs_types:
+                if 'total' in self.mgxs_types or 'transport' in self.mgxs_types:
                     for i in range(len(xsdata.temperatures)):
                         xsdata._absorption[i] = \
                             np.subtract(xsdata._total[i], np.sum(
@@ -1005,9 +1006,11 @@ class Library(object):
 
     def create_mg_library(self, xs_type='macro', xsdata_names=None):
         """Creates an openmc.MGXSLibrary object to contain the MGXS data for the
-        Multi-Group mode of OpenMC. Note that this library will not make use
-        of nested temperature tables. Every dataset in the library will be
-        treated as if it was at the same default temperature.
+        Multi-Group mode of OpenMC.
+
+        Note that this library will not make use of nested temperature tables.
+        Every dataset in the library will be treated as if it was at the same
+        default temperature.
 
         Parameters
         ----------
@@ -1053,7 +1056,7 @@ class Library(object):
         # Initialize file
         mgxs_file = openmc.MGXSLibrary(self.energy_groups)
 
-        if self.domain_type == 'mesh':
+        if self.domain_type is 'mesh':
             # Create the xsdata objects and add to the mgxs_file
             i = 0
             for domain in self.domains:
@@ -1099,14 +1102,15 @@ class Library(object):
     def create_mg_mode(self, xsdata_names=None, bc=['reflective'] * 6):
         """Creates an openmc.MGXSLibrary object to contain the MGXS data for the
         Multi-Group mode of OpenMC as well as the associated openmc.Materials
-        and openmc.Geometry objects. The created Geometry is the same as that
-        used to generate the MGXS data, with the only differences being
-        modifications to point to newly-created Materials which point to the
-        multi-group data. This method only creates a macroscopic
-        MGXS Library even if nuclidic tallies are specified in the Library.
-        Note that this library will not make use of nested temperature tables.
-        Every dataset in the library will be treated as if it was at the same
-        default temperature.
+        and openmc.Geometry objects.
+
+        The created Geometry is the same as that used to generate the MGXS
+        data, with the only differences being modifications to point to
+        newly-created Materials which point to the multi-group data. This
+        method only creates a macroscopic MGXS Library even if nuclidic tallies
+        are specified in the Library. Note that this library will not make
+        use of nested temperature tables. Every dataset in the library will
+        be treated as if it was at the same default temperature.
 
         Parameters
         ----------
@@ -1155,14 +1159,14 @@ class Library(object):
         # the multiple meshes could be overlapping or in disparate regions
         # of the continuous energy model. The next step makes sure there is
         # only one before continuing.
-        if self.domain_type == 'mesh':
+        if self.domain_type is 'mesh':
             cv.check_length("domains", self.domains, 1, 1)
 
         # Get the MGXS File Data
         mgxs_file = self.create_mg_library('macro', xsdata_names)
 
         # Now move on the creating the geometry and assigning materials
-        if self.domain_type == 'mesh':
+        if self.domain_type is 'mesh':
             root = openmc.Universe(name='root', universe_id=0)
 
             # Add cells representative of the mesh with reflective BC
@@ -1208,13 +1212,13 @@ class Library(object):
                 materials.append(material)
 
                 # Differentiate Geometry with new Material
-                if self.domain_type == 'material':
+                if self.domain_type is 'material':
                     # Fill all appropriate Cells with new Material
                     for cell in all_cells:
                         if cell.fill.id == domain.id:
                             cell.fill = material
 
-                elif self.domain_type == 'cell':
+                elif self.domain_type is 'cell':
                     for cell in all_cells:
                         if cell.id == domain.id:
                             cell.fill = material
diff --git a/openmc/mgxs_library.py b/openmc/mgxs_library.py
index 8e6089a1a..67a9b01f4 100644
--- a/openmc/mgxs_library.py
+++ b/openmc/mgxs_library.py
@@ -242,28 +242,28 @@ class XSdata(object):
 
     @property
     def vector_shape(self):
-        if self.representation == 'isotropic':
+        if self.representation is 'isotropic':
             return (self.energy_groups.num_groups,)
-        elif self.representation == 'angle':
+        elif self.representation is 'angle':
             return (self.num_polar, self.num_azimuthal,
                     self.energy_groups.num_groups)
 
     @property
     def matrix_shape(self):
-        if self.representation == 'isotropic':
+        if self.representation is 'isotropic':
             return (self.energy_groups.num_groups,
                     self.energy_groups.num_groups)
-        elif self.representation == 'angle':
+        elif self.representation is 'angle':
             return (self.num_polar, self.num_azimuthal,
                     self.energy_groups.num_groups,
                     self.energy_groups.num_groups)
 
     @property
     def pn_matrix_shape(self):
-        if self.representation == 'isotropic':
+        if self.representation is 'isotropic':
             return (self.num_orders, self.energy_groups.num_groups,
                     self.energy_groups.num_groups)
-        elif self.representation == 'angle':
+        elif self.representation is 'angle':
             return (self.num_polar, self.num_azimuthal, self.num_orders,
                     self.energy_groups.num_groups,
                     self.energy_groups.num_groups)
@@ -297,11 +297,6 @@ class XSdata(object):
         check_greater_than('atomic_weight_ratio', atomic_weight_ratio, 0.0)
         self._atomic_weight_ratio = atomic_weight_ratio
 
-    @fissionable.setter
-    def fissionable(self, fissionable):
-        check_type('fissionable', fissionable, bool)
-        self._fissionable = fissionable
-
     @temperatures.setter
     def temperatures(self, temperatures):
         check_iterable_type('temperatures', temperatures, Real)
@@ -374,8 +369,8 @@ class XSdata(object):
         total: np.ndarray
             Total Cross Section
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         See also
         --------
@@ -389,7 +384,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._total[i] = nptotal
 
     def set_absorption(self, absorption, temperature=294.):
@@ -401,8 +396,8 @@ class XSdata(object):
         absorption: np.ndarray
             Absorption Cross Section
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         See also
         --------
@@ -417,7 +412,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._absorption[i] = npabsorption
 
     def set_fission(self, fission, temperature=294.):
@@ -429,8 +424,8 @@ class XSdata(object):
         fission: np.ndarray
             Fission Cross Section
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         See also
         --------
@@ -444,7 +439,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._fission[i] = npfission
 
         if np.sum(npfission) > 0.0:
@@ -459,8 +454,8 @@ class XSdata(object):
         kappa_fission: np.ndarray
             Kappa-Fission Cross Section
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         See also
         --------
@@ -476,7 +471,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._kappa_fission[i] = npkappa_fission
 
         if np.sum(npkappa_fission) > 0.0:
@@ -491,8 +486,8 @@ class XSdata(object):
         chi: np.ndarray
             Fission Spectrum
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         See also
         --------
@@ -515,7 +510,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._chi[i] = npchi
 
         if self.use_chi is not None:
@@ -530,8 +525,8 @@ class XSdata(object):
         scatter: np.ndarray
             Scattering Matrix Cross Section
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         See also
         --------
@@ -546,7 +541,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._scatter_matrix[i] = npscatter
 
     def set_multiplicity_matrix(self, multiplicity, temperature=294.):
@@ -558,8 +553,8 @@ class XSdata(object):
         multiplicity: np.ndarray
             Multiplicity Matrix Cross Section
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         See also
         --------
@@ -575,7 +570,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._multiplicity_matrix[i] = npmultiplicity
 
     def set_nu_fission(self, nu_fission, temperature=294.):
@@ -587,8 +582,8 @@ class XSdata(object):
         nu_fission: np.ndarray
             Nu-fission Cross Section
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         See also
         --------
@@ -630,7 +625,7 @@ class XSdata(object):
             else:
                 self.use_chi = False
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._nu_fission[i] = npnu_fission
         if np.sum(npnu_fission) > 0.0:
             self._fissionable = True
@@ -644,8 +639,8 @@ class XSdata(object):
         inv_vel: np.ndarray
             Inverse velocities in units of sec/cm.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
 
         """
         check_type('inverse velocities', inv_vel, Iterable,
@@ -657,7 +652,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         self._inverse_velocities[i] = npinv_vel
 
     def set_total_mgxs(self, total, temperature=294., nuclide='total',
@@ -672,8 +667,8 @@ class XSdata(object):
             MGXS Object containing the total or transport cross section
             for the domain of interest.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
         nuclide : str
             Individual nuclide (or 'total' if obtaining material-wise data)
             to gather data for.  Defaults to 'total'.
@@ -699,7 +694,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         if self.representation is 'isotropic':
             self._total[i] = total.get_xs(nuclides=nuclide, xs_type=xs_type,
                                           subdomains=subdomain)
@@ -718,8 +713,8 @@ class XSdata(object):
             MGXS Object containing the absorption cross section
             for the domain of interest.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
         nuclide : str
             Individual nuclide (or 'total' if obtaining material-wise data)
             to gather data for.  Defaults to 'total'.
@@ -745,7 +740,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         if self.representation is 'isotropic':
             self._absorption[i] = absorption.get_xs(nuclides=nuclide,
                                                     xs_type=xs_type,
@@ -765,8 +760,8 @@ class XSdata(object):
             MGXS Object containing the fission cross section
             for the domain of interest.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
         nuclide : str
             Individual nuclide (or 'total' if obtaining material-wise data)
             to gather data for.  Defaults to 'total'.
@@ -792,7 +787,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         if self.representation is 'isotropic':
             self._fission[i] = fission.get_xs(nuclides=nuclide,
                                               xs_type=xs_type,
@@ -812,8 +807,8 @@ class XSdata(object):
             MGXS Object containing the nu-fission cross section
             for the domain of interest.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
         nuclide : str
             Individual nuclide (or 'total' if obtaining material-wise data)
             to gather data for.  Defaults to 'total'.
@@ -840,7 +835,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         if self.representation is 'isotropic':
             self._nu_fission[i] = nu_fission.get_xs(nuclides=nuclide,
                                                     xs_type=xs_type,
@@ -870,8 +865,8 @@ class XSdata(object):
             MGXS Object containing the kappa-fission cross section
             for the domain of interest.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
         nuclide : str
             Individual nuclide (or 'total' if obtaining material-wise data)
             to gather data for.  Defaults to 'total'.
@@ -897,7 +892,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         if self.representation is 'isotropic':
             self._kappa_fission[i] = k_fission.get_xs(nuclides=nuclide,
                                                       xs_type=xs_type,
@@ -916,8 +911,8 @@ class XSdata(object):
         chi: openmc.mgxs.Chi
             MGXS Object containing chi for the domain of interest.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
         nuclide : str
             Individual nuclide (or 'total' if obtaining material-wise data)
             to gather data for.  Defaults to 'total'.
@@ -948,7 +943,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         if self.representation is 'isotropic':
             self._chi[i] = chi.get_xs(nuclides=nuclide,
                                       xs_type=xs_type, subdomains=subdomain)
@@ -973,8 +968,8 @@ class XSdata(object):
             MGXS Object containing the scatter matrix cross section
             for the domain of interest.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
         nuclide : str
             Individual nuclide (or 'total' if obtaining material-wise data)
             to gather data for.  Defaults to 'total'.
@@ -1000,7 +995,7 @@ class XSdata(object):
         check_type('temperature', temperature, Real)
         check_value('temperature', temperature, self.temperatures)
 
-        if (self.scatter_format != 'legendre'):
+        if self.scatter_format is not 'legendre':
             msg = 'Anisotropic scattering representations other than ' \
                   'Legendre expansions have not yet been implemented in ' \
                   'openmc.mgxs.'
@@ -1016,7 +1011,7 @@ class XSdata(object):
             check_value('legendre_order', scatter.legendre_order,
                         [self.order])
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         if self.representation is 'isotropic':
             # Get the scattering orders in the outermost dimension
             self._scatter_matrix[i] = np.zeros((self.num_orders,
@@ -1054,8 +1049,8 @@ class XSdata(object):
             MGXS Object containing the scattering matrix cross section
             for the domain of interest.
         temperature : float
-            Temperature (in units of Kelvin) of the provided dataset. Defaults
-            to 294K
+            Temperature (in Kelvin) of the data. Defaults to room temperature
+            (294K).
         nuclide : str
             Individual nuclide (or 'total' if obtaining material-wise data)
             to gather data for.  Defaults to 'total'.
@@ -1094,7 +1089,7 @@ class XSdata(object):
             check_value('domain_type', scatter.domain_type,
                         ['universe', 'cell', 'material', 'mesh'])
 
-        i = self.temperatures.tolist().index(temperature)
+        i = np.where(self.temperatures == temperature)
         if self.representation is 'isotropic':
             nuscatt = nuscatter.get_xs(nuclides=nuclide,
                                        xs_type=xs_type, moment=0,
@@ -1129,7 +1124,7 @@ class XSdata(object):
         if self.representation is not None:
             grp.attrs['representation'] = np.array(self.representation,
                                                    dtype='S')
-            if self.representation == 'angle':
+            if self.representation is 'angle':
                 if self.num_azimuthal is not None:
                     grp.attrs['num_azimuthal'] = self.num_azimuthal
                 if self.num_polar is not None:
@@ -1176,7 +1171,7 @@ class XSdata(object):
 
             # Get the sparse scattering data to print to the library
             G = self.energy_groups.num_groups
-            if self.representation == 'isotropic':
+            if self.representation is 'isotropic':
                 g_out_bounds = np.zeros((G, 2), dtype=np.int)
                 for g_in in range(G):
                     nz = np.nonzero(self._scatter_matrix[i][0, g_in, :])
@@ -1212,7 +1207,7 @@ class XSdata(object):
                 scatt_grp.create_dataset("g_min", data=g_out_bounds[:, 0])
                 scatt_grp.create_dataset("g_max", data=g_out_bounds[:, 1])
 
-            elif self.representation == 'angle':
+            elif self.representation is 'angle':
                 Np = self.num_polar
                 Na = self.num_azimuthal
                 g_out_bounds = np.zeros((Np, Na, G, 2), dtype=np.int)
diff --git a/scripts/openmc-update-mgxs b/scripts/openmc-update-mgxs
index f16ad9d1b..6122ff626 100755
--- a/scripts/openmc-update-mgxs
+++ b/scripts/openmc-update-mgxs
@@ -51,10 +51,10 @@ def parse_args():
                         help='HDF5 Compression Level')
     args = vars(parser.parse_args())
 
-    if args['output'] == '':
+    if args['output'] is '':
         filename = args['input'].name
         extension = filenameos.path.splitext()
-        if extension == '.xml':
+        if extension is '.xml':
             filename = filename[:filename.rfind('.')] + '.h5'
         args['output'] = filename
 
@@ -75,7 +75,7 @@ def get_data(element, entry):
     return value
 
 
-if __name__ == '__main__':
+if __name__ is '__main__':
     args = parse_args()
 
     # Parse the XML data.
@@ -117,7 +117,7 @@ if __name__ == '__main__':
         representation = get_data(xsdata_elem, 'representation')
         if representation is None:
             representation = 'isotropic'
-        if representation == 'angle':
+        if representation is 'angle':
             n_azi = int(get_data(xsdata_elem, 'num_azimuthal'))
             n_pol = int(get_data(xsdata_elem, 'num_polar'))
 
@@ -146,14 +146,14 @@ if __name__ == '__main__':
                                      representation=representation))
             if awr is not None:
                 xsd[-1].atomic_weight_ratio = awr
-            if representation == 'angle':
+            if representation is 'angle':
                 xsd[-1].num_azimuthal = n_azi
                 xsd[-1].num_polar = n_pol
             xsd[-1].scatter_format = scatter_format
             xsd[-1].order = order
             names.append(name)
 
-        if scatter_format == 'legendre':
+        if scatter_format is 'legendre':
             order_dim = order + 1
         else:
             order_dim = order
diff --git a/src/input_xml.F90 b/src/input_xml.F90
index 8d5628567..fd8a33c68 100644
--- a/src/input_xml.F90
+++ b/src/input_xml.F90
@@ -4673,7 +4673,7 @@ contains
       libraries(i) % materials(1) = names(i)
     end do
 
-    ! Close MGXS HDF file
+    ! Close MGXS HDF5 file
     call file_close(file_id)
 
   end subroutine read_mg_cross_sections_header