diff --git a/examples/python/boxes/build-xml.py b/examples/python/boxes/build-xml.py
index 3eed4059c..175d3f511 100644
--- a/examples/python/boxes/build-xml.py
+++ b/examples/python/boxes/build-xml.py
@@ -34,11 +34,11 @@ moderator = openmc.Material(material_id=3, name='moderator')
 moderator.set_density('g/cc', 1.0)
 moderator.add_nuclide(h1, 2.)
 moderator.add_nuclide(o16, 1.)
-moderator.add_s_alpha_beta('c_H_in_H2O', '71t')
+moderator.add_s_alpha_beta('c_H_in_H2O')
 
 # Instantiate a Materials collection and export to XML
 materials_file = openmc.Materials([fuel1, fuel2, moderator])
-materials_file.default_xs = '71c'
+materials_file.default_temperature = '294K'
 materials_file.export_to_xml()
 
 
diff --git a/examples/python/lattice/hexagonal/build-xml.py b/examples/python/lattice/hexagonal/build-xml.py
index ba2cac367..b131e9dea 100644
--- a/examples/python/lattice/hexagonal/build-xml.py
+++ b/examples/python/lattice/hexagonal/build-xml.py
@@ -29,7 +29,7 @@ moderator = openmc.Material(material_id=2, name='moderator')
 moderator.set_density('g/cc', 1.0)
 moderator.add_nuclide(h1, 2.)
 moderator.add_nuclide(o16, 1.)
-moderator.add_s_alpha_beta('c_H_in_H2O', '71t')
+moderator.add_s_alpha_beta('c_H_in_H2O')
 
 iron = openmc.Material(material_id=3, name='iron')
 iron.set_density('g/cc', 7.9)
@@ -37,7 +37,7 @@ iron.add_nuclide(fe56, 1.)
 
 # Instantiate a Materials collection and export to XML
 materials_file = openmc.Materials([moderator, fuel, iron])
-materials_file.default_xs = '71c'
+materials_file.default_temperature = '294K'
 materials_file.export_to_xml()
 
 
diff --git a/examples/python/lattice/nested/build-xml.py b/examples/python/lattice/nested/build-xml.py
index edf3ad7b1..59962c2c3 100644
--- a/examples/python/lattice/nested/build-xml.py
+++ b/examples/python/lattice/nested/build-xml.py
@@ -28,11 +28,11 @@ moderator = openmc.Material(material_id=2, name='moderator')
 moderator.set_density('g/cc', 1.0)
 moderator.add_nuclide(h1, 2.)
 moderator.add_nuclide(o16, 1.)
-moderator.add_s_alpha_beta('c_H_in_H2O', '71t')
+moderator.add_s_alpha_beta('c_H_in_H2O')
 
 # Instantiate a Materials collection and export to XML
 materials_file = openmc.Materials((moderator, fuel))
-materials_file.default_xs = '71c'
+materials_file.default_temperature = '294K'
 materials_file.export_to_xml()
 
 
diff --git a/examples/python/lattice/simple/build-xml.py b/examples/python/lattice/simple/build-xml.py
index 5ec1b7ee9..ad1c465d4 100644
--- a/examples/python/lattice/simple/build-xml.py
+++ b/examples/python/lattice/simple/build-xml.py
@@ -28,11 +28,11 @@ moderator = openmc.Material(material_id=2, name='moderator')
 moderator.set_density('g/cc', 1.0)
 moderator.add_nuclide(h1, 2.)
 moderator.add_nuclide(o16, 1.)
-moderator.add_s_alpha_beta('c_H_in_H2O', '71t')
+moderator.add_s_alpha_beta('c_H_in_H2O')
 
 # Instantiate a Materials collection and export to XML
 materials_file = openmc.Materials([moderator, fuel])
-materials_file.default_xs = '71c'
+materials_file.default_temperature = '294K'
 materials_file.export_to_xml()
 
 
diff --git a/examples/python/pincell/build-xml.py b/examples/python/pincell/build-xml.py
index 3bda05027..a11ddb7cd 100644
--- a/examples/python/pincell/build-xml.py
+++ b/examples/python/pincell/build-xml.py
@@ -98,11 +98,11 @@ borated_water.add_nuclide(h1, 4.9457e-2)
 borated_water.add_nuclide(h2, 7.4196e-6)
 borated_water.add_nuclide(o16, 2.4672e-2)
 borated_water.add_nuclide(o17, 6.0099e-5)
-borated_water.add_s_alpha_beta('c_H_in_H2O', '71t')
+borated_water.add_s_alpha_beta('c_H_in_H2O')
 
 # Instantiate a Materials collection and export to XML
 materials_file = openmc.Materials([uo2, helium, zircaloy, borated_water])
-materials_file.default_xs = '71c'
+materials_file.default_temperature = '294K'
 materials_file.export_to_xml()
 
 
diff --git a/examples/python/reflective/build-xml.py b/examples/python/reflective/build-xml.py
index 0e064ab61..098fa8620 100644
--- a/examples/python/reflective/build-xml.py
+++ b/examples/python/reflective/build-xml.py
@@ -25,7 +25,7 @@ fuel.add_nuclide(u235, 1.)
 
 # Instantiate a Materials collection and export to XML
 materials_file = openmc.Materials([fuel])
-materials_file.default_xs = '71c'
+materials_file.default_temperature = '294K'
 materials_file.export_to_xml()
 
 
diff --git a/examples/xml/basic/materials.xml b/examples/xml/basic/materials.xml
index 573b96cb2..b7bc2e4e5 100644
--- a/examples/xml/basic/materials.xml
+++ b/examples/xml/basic/materials.xml
@@ -1,12 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <material id="40">
     <density value="4.5" units="g/cc" />
     <nuclide name="U235" ao="1.0" />
-    <temperature>294K</temperature>
   </material>
 
   <material id="41">
@@ -14,7 +13,6 @@
     <nuclide name="H1" ao="2.0" />
     <nuclide name="O16" ao="1.0" />
     <sab name="c_H_in_H2O"/>
-    <temperature>294K</temperature>
   </material>
 
 </materials>
diff --git a/examples/xml/boxes/materials.xml b/examples/xml/boxes/materials.xml
index c74714a08..417fb83ba 100644
--- a/examples/xml/boxes/materials.xml
+++ b/examples/xml/boxes/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <material id="1">
     <density value="4.5" units="g/cc" />
@@ -17,7 +17,7 @@
     <density value="1.0" units="g/cc" />
     <nuclide name="O16" ao="1.0" />
     <nuclide name="H1" ao="2.0" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/examples/xml/lattice/nested/materials.xml b/examples/xml/lattice/nested/materials.xml
index 7f8b06bb1..ddd932fcb 100644
--- a/examples/xml/lattice/nested/materials.xml
+++ b/examples/xml/lattice/nested/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Definition of materials -->
   <material id="1">
@@ -13,7 +13,7 @@
     <density value="1.0" units="g/cc" />
     <nuclide name="H1"  ao="2.0" />
     <nuclide name="O16" ao="1.0" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/examples/xml/lattice/simple/materials.xml b/examples/xml/lattice/simple/materials.xml
index 7f8b06bb1..ddd932fcb 100644
--- a/examples/xml/lattice/simple/materials.xml
+++ b/examples/xml/lattice/simple/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Definition of materials -->
   <material id="1">
@@ -13,7 +13,7 @@
     <density value="1.0" units="g/cc" />
     <nuclide name="H1"  ao="2.0" />
     <nuclide name="O16" ao="1.0" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/examples/xml/pincell/materials.xml b/examples/xml/pincell/materials.xml
index b6af486d1..020c0e676 100644
--- a/examples/xml/pincell/materials.xml
+++ b/examples/xml/pincell/materials.xml
@@ -1,8 +1,8 @@
 <?xml version="1.0"?>
 <materials>
 
-  <!-- By default, use 300K cross sections -->
-  <default_xs>71c</default_xs>
+  <!-- By default, use 294K cross sections -->
+  <default_temperature>294K</default_temperature>
 
   <!--
       Since O-18 is not present in ENDF/B-VII, it was necessary to combine the
@@ -64,7 +64,7 @@
     <nuclide name="H2"   ao="7.4196e-06" />
     <nuclide name="O16"  ao="2.4672e-02" />
     <nuclide name="O17"  ao="6.0099e-05" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/examples/xml/reflective/materials.xml b/examples/xml/reflective/materials.xml
index 13cbf070e..37cfcdc6e 100644
--- a/examples/xml/reflective/materials.xml
+++ b/examples/xml/reflective/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <material id="1">
     <density value="4.5" units="g/cc" />
diff --git a/openmc/summary.py b/openmc/summary.py
index 6fbace72e..3e25f2c26 100644
--- a/openmc/summary.py
+++ b/openmc/summary.py
@@ -113,6 +113,7 @@ class Summary(object):
             material_id = int(key.lstrip('material '))
             index = self._f['materials'][key]['index'].value
             name = self._f['materials'][key]['name'].value.decode()
+            temperature = self._f['materials'][key]['temperature'].value.decode()
             density = self._f['materials'][key]['atom_density'].value
             nuc_densities = self._f['materials'][key]['nuclide_densities'][...]
             nuclides = self._f['materials'][key]['nuclides'].value
@@ -124,22 +125,21 @@ class Summary(object):
             if 'sab_names' in self._f['materials'][key]:
                 sab_tables = self._f['materials'][key]['sab_names'].value
                 for sab_table in sab_tables:
-                    name, xs = sab_table.decode().split('.')
-                    material.add_s_alpha_beta(name, xs)
+                    name = sab_table.decode()
+                    material.add_s_alpha_beta(name)
 
             # Set the Material's density to atom/b-cm as used by OpenMC
             material.set_density(density=density, units='atom/b-cm')
 
             # Add all nuclides to the Material
             for fullname, density in zip(nuclides, nuc_densities):
-                fullname = fullname.decode().strip()
-                name, xs = fullname.split('.')
+                name = fullname.decode().strip()
 
                 if 'nat' in name:
-                    material.add_element(openmc.Element(name=name, xs=xs),
+                    material.add_element(openmc.Element(name=name),
                                          percent=density, percent_type='ao')
                 else:
-                    material.add_nuclide(openmc.Nuclide(name=name, xs=xs),
+                    material.add_nuclide(openmc.Nuclide(name=name),
                                          percent=density, percent_type='ao')
 
             # Add the Material to the global dictionary of all Materials
diff --git a/src/input_xml.F90 b/src/input_xml.F90
index d827cfad1..ef927c35e 100644
--- a/src/input_xml.F90
+++ b/src/input_xml.F90
@@ -2211,7 +2211,7 @@ contains
       else if (default_temperature /= '') then
         mat % temperature = default_temperature
       else
-        call fatal_error("Must specify eithe a material temperature or a &
+        call fatal_error("Must specify either a material temperature or a &
                          &default temperature")
       end if
 
diff --git a/src/summary.F90 b/src/summary.F90
index b02336d97..5bd440ff3 100644
--- a/src/summary.F90
+++ b/src/summary.F90
@@ -527,10 +527,13 @@ contains
       call write_dataset(material_group, "index", i)
 
       ! Write name for this material
-      call write_dataset(material_group, "name", m%name)
+      call write_dataset(material_group, "name", m % name)
+
+      ! Write temperature for this material
+      call write_dataset(material_group, "temperature", m % temperature)
 
       ! Write atom density with units
-      call write_dataset(material_group, "atom_density", m%density)
+      call write_dataset(material_group, "atom_density", m % density)
       call write_attribute_string(material_group, "atom_density", "units", &
            "atom/b-cm")
 
@@ -572,7 +575,6 @@ contains
     integer(HID_T), intent(in) :: file_id
 
     integer :: i, j, k
-    integer :: i_xs
     integer :: n_order      ! loop index for moment orders
     integer :: nm_order     ! loop index for Ynm moment orders
     integer(HID_T) :: tallies_group
@@ -635,12 +637,7 @@ contains
       allocate(str_array(t%n_nuclide_bins))
       NUCLIDE_LOOP: do j = 1, t%n_nuclide_bins
         if (t%nuclide_bins(j) > 0) then
-          i_xs = index(nuclides(t%nuclide_bins(j))%name, '.')
-          if (i_xs > 0) then
-            str_array(j) = nuclides(t%nuclide_bins(j))%name(1 : i_xs-1)
-          else
-            str_array(j) = nuclides(t%nuclide_bins(j))%name
-          end if
+          str_array(j) = nuclides(t % nuclide_bins(j)) % name
         else
           str_array(j) = 'total'
         end if
diff --git a/tests/test_asymmetric_lattice/inputs_true.dat b/tests/test_asymmetric_lattice/inputs_true.dat
index d503a3a0b..997d74ba8 100644
--- a/tests/test_asymmetric_lattice/inputs_true.dat
+++ b/tests/test_asymmetric_lattice/inputs_true.dat
@@ -1 +1 @@
-a55899cd2ed0a8ec5d44003139da639f87f5f03ee76b2d6577db6a8c2014849e4277f8e68fa874ac6795e4cbc4eb6e4031d726cafe6e663e84787d1ecd8e7f86
\ No newline at end of file
+7b62ec28ffec0028dc07ed23b720ae3f97b00aa15b319dc3991d9f1f88fcae8bffc7ccd2385d2b848180a57120624061ff4fe10745a3187e3e64fee0faface8d
\ No newline at end of file
diff --git a/tests/test_cmfd_feed/materials.xml b/tests/test_cmfd_feed/materials.xml
index 8f32169d9..f773d83d0 100644
--- a/tests/test_cmfd_feed/materials.xml
+++ b/tests/test_cmfd_feed/materials.xml
@@ -1,12 +1,14 @@
 <?xml version="1.0"?>
 <materials>
 
+<default_temperature>294K</default_temperature>
+
 <!-- Definition of materials -->
   <material id="1">
     <density value="19" units="g/cc" />
-    <nuclide name="U235" xs="71c" wo="0.21" />
-    <nuclide name="U238" xs="71c" wo="0.68" />
-    <nuclide name="O16" xs="71c" wo="0.11" />
+    <nuclide name="U235" wo="0.21" />
+    <nuclide name="U238" wo="0.68" />
+    <nuclide name="O16" wo="0.11" />
   </material>
 
 </materials>
diff --git a/tests/test_cmfd_nofeed/materials.xml b/tests/test_cmfd_nofeed/materials.xml
index 8f32169d9..f773d83d0 100644
--- a/tests/test_cmfd_nofeed/materials.xml
+++ b/tests/test_cmfd_nofeed/materials.xml
@@ -1,12 +1,14 @@
 <?xml version="1.0"?>
 <materials>
 
+<default_temperature>294K</default_temperature>
+
 <!-- Definition of materials -->
   <material id="1">
     <density value="19" units="g/cc" />
-    <nuclide name="U235" xs="71c" wo="0.21" />
-    <nuclide name="U238" xs="71c" wo="0.68" />
-    <nuclide name="O16" xs="71c" wo="0.11" />
+    <nuclide name="U235" wo="0.21" />
+    <nuclide name="U238" wo="0.68" />
+    <nuclide name="O16" wo="0.11" />
   </material>
 
 </materials>
diff --git a/tests/test_complex_cell/materials.xml b/tests/test_complex_cell/materials.xml
index a9e69b8bc..857626d5a 100644
--- a/tests/test_complex_cell/materials.xml
+++ b/tests/test_complex_cell/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <material id="1">
     <density value="4.5" units="g/cc" />
diff --git a/tests/test_confidence_intervals/materials.xml b/tests/test_confidence_intervals/materials.xml
index 23d7f969d..e1124a303 100644
--- a/tests/test_confidence_intervals/materials.xml
+++ b/tests/test_confidence_intervals/materials.xml
@@ -2,8 +2,9 @@
 <materials>
 
   <material id="1">
+    <temperature>294K</temperature>
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_density/materials.xml b/tests/test_density/materials.xml
index c474c5c65..53a7b0fcb 100644
--- a/tests/test_density/materials.xml
+++ b/tests/test_density/materials.xml
@@ -1,26 +1,28 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="0.1" units="atom/b-cm" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
   <material id="2">
     <density value="4.5e22" units="atom/cm3" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
   <material id="3">
     <density value="12.3e3" units="kg/m3" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
   <material id="4">
     <density units="sum" />
-    <nuclide name="U235" xs="71c" ao="0.3e-2" />
-    <nuclide name="U238" xs="71c" ao="0.5e-1" />
-    <nuclide name="H1" xs="71c" ao="0.1e-2" />
+    <nuclide name="U235" ao="0.3e-2" />
+    <nuclide name="U238" ao="0.5e-1" />
+    <nuclide name="H1" ao="0.1e-2" />
   </material>
 
 </materials>
diff --git a/tests/test_distribmat/inputs_true.dat b/tests/test_distribmat/inputs_true.dat
index 1212a28e5..d21da2f89 100644
--- a/tests/test_distribmat/inputs_true.dat
+++ b/tests/test_distribmat/inputs_true.dat
@@ -1 +1 @@
-46df57157980545d90b482acfb01f525b84c0e623fa93a5d9c08a65723d677ef1c092360219a3c7fcf5110c6ba32f1eacbd5c5eaed40be4bfe154f302400c0a4
\ No newline at end of file
+6ae54c198e7659503d297e40be746a5bd72b35909fceed4b3ef357876b781946c0ea5021342556ef21f4034fa9e42b2c6014077c0efd3459dc063e6da4b12b59
\ No newline at end of file
diff --git a/tests/test_distribmat/test_distribmat.py b/tests/test_distribmat/test_distribmat.py
index a8d013996..29c5d638f 100644
--- a/tests/test_distribmat/test_distribmat.py
+++ b/tests/test_distribmat/test_distribmat.py
@@ -29,7 +29,7 @@ class DistribmatTestHarness(PyAPITestHarness):
         light_fuel.add_nuclide('U235', 1.0)
 
         mats_file = openmc.Materials([moderator, dense_fuel, light_fuel])
-        mats_file.default_xs = '71c'
+        mats_file.default_temperature = '294K'
         mats_file.export_to_xml()
 
 
diff --git a/tests/test_eigenvalue_genperbatch/materials.xml b/tests/test_eigenvalue_genperbatch/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_eigenvalue_genperbatch/materials.xml
+++ b/tests/test_eigenvalue_genperbatch/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_eigenvalue_no_inactive/materials.xml b/tests/test_eigenvalue_no_inactive/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_eigenvalue_no_inactive/materials.xml
+++ b/tests/test_eigenvalue_no_inactive/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_energy_grid/materials.xml b/tests/test_energy_grid/materials.xml
index ed9b38d90..2946a8d60 100644
--- a/tests/test_energy_grid/materials.xml
+++ b/tests/test_energy_grid/materials.xml
@@ -1,11 +1,13 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
-    <nuclide name="H1" xs="71c" ao="0.5" />
-    <nuclide name="C0" xs="71c" ao="0.5" />
+    <nuclide name="U235" ao="1.0" />
+    <nuclide name="H1" ao="0.5" />
+    <nuclide name="C0" ao="0.5" />
   </material>
 
 </materials>
diff --git a/tests/test_energy_laws/materials.xml b/tests/test_energy_laws/materials.xml
index c70e071cf..e7acd32e2 100644
--- a/tests/test_energy_laws/materials.xml
+++ b/tests/test_energy_laws/materials.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <materials>
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
   <material id="1">
     <density value="20" units="g/cc" />
     <nuclide name="U233" ao="1.0" />
diff --git a/tests/test_entropy/materials.xml b/tests/test_entropy/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_entropy/materials.xml
+++ b/tests/test_entropy/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_filter_distribcell/case-1/materials.xml b/tests/test_filter_distribcell/case-1/materials.xml
index 891cc9fd0..afd4b05b7 100644
--- a/tests/test_filter_distribcell/case-1/materials.xml
+++ b/tests/test_filter_distribcell/case-1/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Definition of materials -->
   <material id="1">
diff --git a/tests/test_filter_distribcell/case-2/materials.xml b/tests/test_filter_distribcell/case-2/materials.xml
index 891cc9fd0..afd4b05b7 100644
--- a/tests/test_filter_distribcell/case-2/materials.xml
+++ b/tests/test_filter_distribcell/case-2/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Definition of materials -->
   <material id="1">
diff --git a/tests/test_filter_distribcell/case-3/materials.xml b/tests/test_filter_distribcell/case-3/materials.xml
index 6a5916a83..f03693e52 100644
--- a/tests/test_filter_distribcell/case-3/materials.xml
+++ b/tests/test_filter_distribcell/case-3/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Fuel composition -->
   <material id="1">
diff --git a/tests/test_filter_distribcell/case-4/materials.xml b/tests/test_filter_distribcell/case-4/materials.xml
index ab9f8688e..15cf0c54b 100644
--- a/tests/test_filter_distribcell/case-4/materials.xml
+++ b/tests/test_filter_distribcell/case-4/materials.xml
@@ -1,18 +1,21 @@
 <?xml version='1.0' encoding='utf-8'?>
 <materials>
-    <default_xs>71c</default_xs>
-<material id="1" name="fuel">
-        <density units="g/cc" value="4.5" />
-    <nuclide ao="1.0" name="U235" />
+    <default_temperature>294K</default_temperature>
+
+    <material id="1" name="fuel">
+      <density units="g/cc" value="4.5" />
+      <nuclide ao="1.0" name="U235" />
     </material>
-<material id="2" name="moderator">
-        <density units="g/cc" value="1.0" />
-    <nuclide ao="1.0" name="O16" />
-    <nuclide ao="2.0" name="H1" />
-    <sab name="c_H_in_H2O" xs="71t" />
+
+    <material id="2" name="moderator">
+      <density units="g/cc" value="1.0" />
+      <nuclide ao="1.0" name="O16" />
+      <nuclide ao="2.0" name="H1" />
+      <sab name="c_H_in_H2O" />
     </material>
-<material id="3" name="iron">
-        <density units="g/cc" value="7.9" />
-    <nuclide ao="1.0" name="Fe56" />
+
+    <material id="3" name="iron">
+      <density units="g/cc" value="7.9" />
+      <nuclide ao="1.0" name="Fe56" />
     </material>
 </materials>
diff --git a/tests/test_filter_mesh_2d/materials.xml b/tests/test_filter_mesh_2d/materials.xml
index f5a9e61be..bead58f8b 100644
--- a/tests/test_filter_mesh_2d/materials.xml
+++ b/tests/test_filter_mesh_2d/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Fuel composition -->
   <material id="1">
@@ -59,7 +59,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Hot borated water -->
@@ -69,7 +69,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- RPV Composition -->
@@ -128,7 +128,7 @@
     <nuclide name="Cr52" wo="0.145407678031" />
     <nuclide name="Cr53" wo="0.016806340306" />
     <nuclide name="Cr54" wo="0.004261520857" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Upper radial reflector / Top plate region -->
@@ -155,7 +155,7 @@
     <nuclide name="Cr52" wo="0.146766614995" />
     <nuclide name="Cr53" wo="0.01696340737" />
     <nuclide name="Cr54" wo="0.004301347765" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom plate region -->
@@ -182,7 +182,7 @@
     <nuclide name="Cr52" wo="0.157390026871" />
     <nuclide name="Cr53" wo="0.018191270146" />
     <nuclide name="Cr54" wo="0.004612692337" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom nozzle region -->
@@ -209,7 +209,7 @@
     <nuclide name="Cr52" wo="0.124142524198" />
     <nuclide name="Cr53" wo="0.014348496148" />
     <nuclide name="Cr54" wo="0.003638294506" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top nozzle region -->
@@ -236,7 +236,7 @@
     <nuclide name="Cr52" wo="0.107931450781" />
     <nuclide name="Cr53" wo="0.012474806806" />
     <nuclide name="Cr54" wo="0.003163190107" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top of Fuel Assemblies -->
@@ -251,7 +251,7 @@
     <nuclide name="Zr92" wo="0.14759527104" />
     <nuclide name="Zr94" wo="0.15280552077" />
     <nuclide name="Zr96" wo="0.02511169542" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom of Fuel Assemblies -->
@@ -266,7 +266,7 @@
     <nuclide name="Zr92" wo="0.1274914944" />
     <nuclide name="Zr94" wo="0.1319920622" />
     <nuclide name="Zr96" wo="0.0216912612" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/tests/test_filter_mesh_3d/materials.xml b/tests/test_filter_mesh_3d/materials.xml
index f5a9e61be..bead58f8b 100644
--- a/tests/test_filter_mesh_3d/materials.xml
+++ b/tests/test_filter_mesh_3d/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Fuel composition -->
   <material id="1">
@@ -59,7 +59,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Hot borated water -->
@@ -69,7 +69,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- RPV Composition -->
@@ -128,7 +128,7 @@
     <nuclide name="Cr52" wo="0.145407678031" />
     <nuclide name="Cr53" wo="0.016806340306" />
     <nuclide name="Cr54" wo="0.004261520857" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Upper radial reflector / Top plate region -->
@@ -155,7 +155,7 @@
     <nuclide name="Cr52" wo="0.146766614995" />
     <nuclide name="Cr53" wo="0.01696340737" />
     <nuclide name="Cr54" wo="0.004301347765" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom plate region -->
@@ -182,7 +182,7 @@
     <nuclide name="Cr52" wo="0.157390026871" />
     <nuclide name="Cr53" wo="0.018191270146" />
     <nuclide name="Cr54" wo="0.004612692337" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom nozzle region -->
@@ -209,7 +209,7 @@
     <nuclide name="Cr52" wo="0.124142524198" />
     <nuclide name="Cr53" wo="0.014348496148" />
     <nuclide name="Cr54" wo="0.003638294506" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top nozzle region -->
@@ -236,7 +236,7 @@
     <nuclide name="Cr52" wo="0.107931450781" />
     <nuclide name="Cr53" wo="0.012474806806" />
     <nuclide name="Cr54" wo="0.003163190107" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top of Fuel Assemblies -->
@@ -251,7 +251,7 @@
     <nuclide name="Zr92" wo="0.14759527104" />
     <nuclide name="Zr94" wo="0.15280552077" />
     <nuclide name="Zr96" wo="0.02511169542" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom of Fuel Assemblies -->
@@ -266,7 +266,7 @@
     <nuclide name="Zr92" wo="0.1274914944" />
     <nuclide name="Zr94" wo="0.1319920622" />
     <nuclide name="Zr96" wo="0.0216912612" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/tests/test_fixed_source/materials.xml b/tests/test_fixed_source/materials.xml
index 6c52b2501..cfd0efd6c 100644
--- a/tests/test_fixed_source/materials.xml
+++ b/tests/test_fixed_source/materials.xml
@@ -1,10 +1,12 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="7.5" units="g/cc" />
-    <nuclide name="O16" xs="71c" ao="1.0" />
-    <nuclide name="U238" xs="71c" ao="0.0001" />
+    <nuclide name="O16" ao="1.0" />
+    <nuclide name="U238" ao="0.0001" />
   </material>
 
 </materials>
diff --git a/tests/test_infinite_cell/materials.xml b/tests/test_infinite_cell/materials.xml
index 1c2d64942..8bd6c820b 100644
--- a/tests/test_infinite_cell/materials.xml
+++ b/tests/test_infinite_cell/materials.xml
@@ -1,14 +1,16 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
   <material id="2">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U238" xs="71c" ao="1.0" />
+    <nuclide name="U238" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_iso_in_lab/inputs_true.dat b/tests/test_iso_in_lab/inputs_true.dat
index 34f522872..0298e581c 100644
--- a/tests/test_iso_in_lab/inputs_true.dat
+++ b/tests/test_iso_in_lab/inputs_true.dat
@@ -1 +1 @@
-c05fdb7815ccc1dcd2f260429b9139ad96ad4a7d1643e2bb938e3cd61268451363538ef4e41c5eaf73a64dbace43b2bd4489d5ff012a33104c2c1d6fa61146eb
\ No newline at end of file
+a84e601e6ba0891aaeaa37b1aa55076fecee598bb46be2b99dcdedab597b5d7e1731e2a0dc265df2ad6f475e33dae91a3cc27bc23d0c37be25a097ea83e74fd6
\ No newline at end of file
diff --git a/tests/test_lattice/materials.xml b/tests/test_lattice/materials.xml
index 67240c4c9..91772da79 100644
--- a/tests/test_lattice/materials.xml
+++ b/tests/test_lattice/materials.xml
@@ -10,7 +10,7 @@
   ===============================================================
   -->
 
-  <default_xs>71c</default_xs>  
+  <default_temperature>294K</default_temperature>
 
   <!-- UO2-PuO2 Mixture -->
   <material id="1">
@@ -27,7 +27,7 @@
     <nuclide name="U238"  ao="2.0611e-02" />
     <nuclide name="O16"   ao="4.3779e-02" />
   </material>
-    
+
   <!-- Natural UO2 Layer -->
   <material id="2">
     <density value="9.286" units="g/cm3" />
@@ -37,7 +37,7 @@
     <nuclide name="U238"  ao="2.0525e-02" />
     <nuclide name="O16"   ao="4.1943e-02" />
   </material>
-    
+
   <!-- Cladding -->
   <material id="3">
     <density units="sum" />
@@ -75,7 +75,7 @@
     <nuclide name="Zr94" ao="7.4075e-03" />
     <nuclide name="Zr96" ao="1.1934e-03" />
   </material>
-    
+
   <!-- Moderator -->
   <material id="4">
     <density units="sum" />
@@ -88,9 +88,9 @@
     <!-- Boron at 1.7 ppm -->
     <nuclide name="B10" ao="1.8706e-08" />
     <nuclide name="B11" ao="7.5770e-08" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
-    
+
   <!-- 6061 Aluminum -->
   <material id="5">
     <density units="sum" />
@@ -128,7 +128,7 @@
     <!-- Al at 5.8433e-2 atom/b-cm -->
     <nuclide name="Al27" ao="5.8433e-02" />
   </material>
-    
+
   <!-- Lead -->
   <material id="6">
     <density value="3.2174e-02" units="atom/b-cm" />
diff --git a/tests/test_lattice_hex/materials.xml b/tests/test_lattice_hex/materials.xml
index 92d10fa81..90b79b7b4 100644
--- a/tests/test_lattice_hex/materials.xml
+++ b/tests/test_lattice_hex/materials.xml
@@ -1,42 +1,44 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
 <!-- Material 01: Water -->
   <material id="01">
     <density value="0.998" units="g/cc"/>
-    <nuclide name="H1"  xs="71c" ao="2.0"/>
-    <nuclide name="O16" xs="71c" ao="1.0"/>
-    <nuclide name="B10" xs="71c" ao="0.00085"/>
+    <nuclide name="H1"  ao="2.0"/>
+    <nuclide name="O16" ao="1.0"/>
+    <nuclide name="B10" ao="0.00085"/>
   </material>
 
 <!-- Material 13: Fuel (3.30%) -->
   <material id="13">
     <density value="10.371" units="g/cc"/>
-    <nuclide name="U235" xs="71c" ao="0.033408078"/>
-    <nuclide name="U238" xs="71c" ao="0.966591922"/>
-    <nuclide name="O16"  xs="71c" ao="2.0"/>
+    <nuclide name="U235" ao="0.033408078"/>
+    <nuclide name="U238" ao="0.966591922"/>
+    <nuclide name="O16"  ao="2.0"/>
   </material>
 
 <!-- Material 21: Zircaloy -->
   <material id="21">
     <density value="6.44" units="g/cc" />
-    <nuclide name="Zr90"  xs="71c" wo="0.501807"/>
-    <nuclide name="Zr91"  xs="71c" wo="0.110712"/>
-    <nuclide name="Zr92"  xs="71c" wo="0.170991"/>
-    <nuclide name="Zr94"  xs="71c" wo="0.177057"/>
-    <nuclide name="Zr96"  xs="71c" wo="0.029133"/>
+    <nuclide name="Zr90"  wo="0.501807"/>
+    <nuclide name="Zr91"  wo="0.110712"/>
+    <nuclide name="Zr92"  wo="0.170991"/>
+    <nuclide name="Zr94"  wo="0.177057"/>
+    <nuclide name="Zr96"  wo="0.029133"/>
   </material>
 
 <!-- Material 22: Steel -->
   <material id="22">
     <density value="7.9" units="g/cc"/>
-    <nuclide name="Mn55" xs="71c" wo="2"/>
-    <nuclide name="Ni58" xs="71c" wo="6.83"/>
-    <nuclide name="Ni60" xs="71c" wo="2.61"/>
-    <nuclide name="Cr53" xs="71c" wo="1.71"/>
-    <nuclide name="Fe54" xs="71c" wo="3.98257"/>
-    <nuclide name="Fe56" xs="71c" wo="63.03447"/>
-    <nuclide name="Fe57" xs="71c" wo="1.4763"/>
+    <nuclide name="Mn55" wo="2"/>
+    <nuclide name="Ni58" wo="6.83"/>
+    <nuclide name="Ni60" wo="2.61"/>
+    <nuclide name="Cr53" wo="1.71"/>
+    <nuclide name="Fe54" wo="3.98257"/>
+    <nuclide name="Fe56" wo="63.03447"/>
+    <nuclide name="Fe57" wo="1.4763"/>
   </material>
 
 </materials>
diff --git a/tests/test_lattice_mixed/materials.xml b/tests/test_lattice_mixed/materials.xml
index 92d10fa81..90b79b7b4 100644
--- a/tests/test_lattice_mixed/materials.xml
+++ b/tests/test_lattice_mixed/materials.xml
@@ -1,42 +1,44 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
 <!-- Material 01: Water -->
   <material id="01">
     <density value="0.998" units="g/cc"/>
-    <nuclide name="H1"  xs="71c" ao="2.0"/>
-    <nuclide name="O16" xs="71c" ao="1.0"/>
-    <nuclide name="B10" xs="71c" ao="0.00085"/>
+    <nuclide name="H1"  ao="2.0"/>
+    <nuclide name="O16" ao="1.0"/>
+    <nuclide name="B10" ao="0.00085"/>
   </material>
 
 <!-- Material 13: Fuel (3.30%) -->
   <material id="13">
     <density value="10.371" units="g/cc"/>
-    <nuclide name="U235" xs="71c" ao="0.033408078"/>
-    <nuclide name="U238" xs="71c" ao="0.966591922"/>
-    <nuclide name="O16"  xs="71c" ao="2.0"/>
+    <nuclide name="U235" ao="0.033408078"/>
+    <nuclide name="U238" ao="0.966591922"/>
+    <nuclide name="O16"  ao="2.0"/>
   </material>
 
 <!-- Material 21: Zircaloy -->
   <material id="21">
     <density value="6.44" units="g/cc" />
-    <nuclide name="Zr90"  xs="71c" wo="0.501807"/>
-    <nuclide name="Zr91"  xs="71c" wo="0.110712"/>
-    <nuclide name="Zr92"  xs="71c" wo="0.170991"/>
-    <nuclide name="Zr94"  xs="71c" wo="0.177057"/>
-    <nuclide name="Zr96"  xs="71c" wo="0.029133"/>
+    <nuclide name="Zr90"  wo="0.501807"/>
+    <nuclide name="Zr91"  wo="0.110712"/>
+    <nuclide name="Zr92"  wo="0.170991"/>
+    <nuclide name="Zr94"  wo="0.177057"/>
+    <nuclide name="Zr96"  wo="0.029133"/>
   </material>
 
 <!-- Material 22: Steel -->
   <material id="22">
     <density value="7.9" units="g/cc"/>
-    <nuclide name="Mn55" xs="71c" wo="2"/>
-    <nuclide name="Ni58" xs="71c" wo="6.83"/>
-    <nuclide name="Ni60" xs="71c" wo="2.61"/>
-    <nuclide name="Cr53" xs="71c" wo="1.71"/>
-    <nuclide name="Fe54" xs="71c" wo="3.98257"/>
-    <nuclide name="Fe56" xs="71c" wo="63.03447"/>
-    <nuclide name="Fe57" xs="71c" wo="1.4763"/>
+    <nuclide name="Mn55" wo="2"/>
+    <nuclide name="Ni58" wo="6.83"/>
+    <nuclide name="Ni60" wo="2.61"/>
+    <nuclide name="Cr53" wo="1.71"/>
+    <nuclide name="Fe54" wo="3.98257"/>
+    <nuclide name="Fe56" wo="63.03447"/>
+    <nuclide name="Fe57" wo="1.4763"/>
   </material>
 
 </materials>
diff --git a/tests/test_lattice_multiple/materials.xml b/tests/test_lattice_multiple/materials.xml
index f5a9e61be..bead58f8b 100644
--- a/tests/test_lattice_multiple/materials.xml
+++ b/tests/test_lattice_multiple/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Fuel composition -->
   <material id="1">
@@ -59,7 +59,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Hot borated water -->
@@ -69,7 +69,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- RPV Composition -->
@@ -128,7 +128,7 @@
     <nuclide name="Cr52" wo="0.145407678031" />
     <nuclide name="Cr53" wo="0.016806340306" />
     <nuclide name="Cr54" wo="0.004261520857" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Upper radial reflector / Top plate region -->
@@ -155,7 +155,7 @@
     <nuclide name="Cr52" wo="0.146766614995" />
     <nuclide name="Cr53" wo="0.01696340737" />
     <nuclide name="Cr54" wo="0.004301347765" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom plate region -->
@@ -182,7 +182,7 @@
     <nuclide name="Cr52" wo="0.157390026871" />
     <nuclide name="Cr53" wo="0.018191270146" />
     <nuclide name="Cr54" wo="0.004612692337" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom nozzle region -->
@@ -209,7 +209,7 @@
     <nuclide name="Cr52" wo="0.124142524198" />
     <nuclide name="Cr53" wo="0.014348496148" />
     <nuclide name="Cr54" wo="0.003638294506" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top nozzle region -->
@@ -236,7 +236,7 @@
     <nuclide name="Cr52" wo="0.107931450781" />
     <nuclide name="Cr53" wo="0.012474806806" />
     <nuclide name="Cr54" wo="0.003163190107" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top of Fuel Assemblies -->
@@ -251,7 +251,7 @@
     <nuclide name="Zr92" wo="0.14759527104" />
     <nuclide name="Zr94" wo="0.15280552077" />
     <nuclide name="Zr96" wo="0.02511169542" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom of Fuel Assemblies -->
@@ -266,7 +266,7 @@
     <nuclide name="Zr92" wo="0.1274914944" />
     <nuclide name="Zr94" wo="0.1319920622" />
     <nuclide name="Zr96" wo="0.0216912612" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/tests/test_mg_nuclide/inputs_true.dat b/tests/test_mg_nuclide/inputs_true.dat
index e0af3352b..18811f285 100644
--- a/tests/test_mg_nuclide/inputs_true.dat
+++ b/tests/test_mg_nuclide/inputs_true.dat
@@ -1 +1 @@
-0efba3dd7882fdd38756d0a8f01ff00d7a1abdaab6430b3f090f3339e552448453bbb733852b6bd6ff09608d923c282f168320f942fc2eb3a45610873c588734
\ No newline at end of file
+be296da93031694b2915e1a10e3e6fd663d612cdd29a84745e3ccb0065c088b4bcda45f6919962f6ee784efe52ebe178bf7d3ce019859637ae57c2da1e240a04
\ No newline at end of file
diff --git a/tests/test_mgxs_library_ce_to_mg/inputs_true.dat b/tests/test_mgxs_library_ce_to_mg/inputs_true.dat
index 332c2df5f..e48c50d0a 100644
--- a/tests/test_mgxs_library_ce_to_mg/inputs_true.dat
+++ b/tests/test_mgxs_library_ce_to_mg/inputs_true.dat
@@ -1 +1 @@
-fb9c9180f692198548ca14543b29a8b623b382a19932999b2140ca4dd440f2102ba2fdbcb500ede3b8829aa85e1b4498151d280f1422d2d6b1bb5789aff34d71
\ No newline at end of file
+a33f770307b365103c5d71aa3e70deebd78d3a2fa90e88632641c1a40d64d19de0ce3c95c858aedf3beccc5de64cac434e1cd55b2b162ed315c78450c53a24a4
\ No newline at end of file
diff --git a/tests/test_mgxs_library_condense/inputs_true.dat b/tests/test_mgxs_library_condense/inputs_true.dat
index e58015868..c261a0ede 100644
--- a/tests/test_mgxs_library_condense/inputs_true.dat
+++ b/tests/test_mgxs_library_condense/inputs_true.dat
@@ -1 +1 @@
-08c5f1c783dd88c5fed51c054718ca09fc4e99aa4560a6f928b3902991948f3a878d055ac46c07548904285c2c5f22dc2a3d8c1bb82b8e73d76dd790820117df
\ No newline at end of file
+df2e5370925785e061e094561e9d2048c3104aaecf533ee9590a187d4597e53b489fb6e8cc54ed878f7d313bcf00586edceae4ff712c837faaa5ddab0ad378b3
\ No newline at end of file
diff --git a/tests/test_mgxs_library_distribcell/inputs_true.dat b/tests/test_mgxs_library_distribcell/inputs_true.dat
index 924c53838..2ca1810e9 100644
--- a/tests/test_mgxs_library_distribcell/inputs_true.dat
+++ b/tests/test_mgxs_library_distribcell/inputs_true.dat
@@ -1 +1 @@
-9ce3d6987d67e92b0924916bb54288429d2bd6dfd12a69f86c5dbefb407f7eb72adb0e44d558c09e9a39610ffeb651aee4aedc629cf3a28a181d62ca4cfbcd5a
\ No newline at end of file
+687358da3e7d658b6187e1d76280437d5b1a97a7ca3920483792e74de6fa9556fa86f4d55150c03d8628b3aa424afa187d8745f087f252ad0fca44ccc2a85f4c
\ No newline at end of file
diff --git a/tests/test_mgxs_library_hdf5/inputs_true.dat b/tests/test_mgxs_library_hdf5/inputs_true.dat
index e58015868..c261a0ede 100644
--- a/tests/test_mgxs_library_hdf5/inputs_true.dat
+++ b/tests/test_mgxs_library_hdf5/inputs_true.dat
@@ -1 +1 @@
-08c5f1c783dd88c5fed51c054718ca09fc4e99aa4560a6f928b3902991948f3a878d055ac46c07548904285c2c5f22dc2a3d8c1bb82b8e73d76dd790820117df
\ No newline at end of file
+df2e5370925785e061e094561e9d2048c3104aaecf533ee9590a187d4597e53b489fb6e8cc54ed878f7d313bcf00586edceae4ff712c837faaa5ddab0ad378b3
\ No newline at end of file
diff --git a/tests/test_mgxs_library_mesh/inputs_true.dat b/tests/test_mgxs_library_mesh/inputs_true.dat
index f62e0aa05..4cebb274e 100644
--- a/tests/test_mgxs_library_mesh/inputs_true.dat
+++ b/tests/test_mgxs_library_mesh/inputs_true.dat
@@ -1 +1 @@
-5f167bdd4d6ae5873d48483e85aceaec8a934239ed5a50ef6f6500ce204f5851ae330621a5007f3b3d6bdab49f2cd627d011c1f6e6983fec958a6984eb9cb7ca
\ No newline at end of file
+7f3aec9cedab76262de3706427ccba88b4c81fd4c9a033ff5467671ca21abe13b3981100d688502818bdd0534db22438970b02d652ca9d105557276de2d2a550
\ No newline at end of file
diff --git a/tests/test_mgxs_library_no_nuclides/inputs_true.dat b/tests/test_mgxs_library_no_nuclides/inputs_true.dat
index e58015868..c261a0ede 100644
--- a/tests/test_mgxs_library_no_nuclides/inputs_true.dat
+++ b/tests/test_mgxs_library_no_nuclides/inputs_true.dat
@@ -1 +1 @@
-08c5f1c783dd88c5fed51c054718ca09fc4e99aa4560a6f928b3902991948f3a878d055ac46c07548904285c2c5f22dc2a3d8c1bb82b8e73d76dd790820117df
\ No newline at end of file
+df2e5370925785e061e094561e9d2048c3104aaecf533ee9590a187d4597e53b489fb6e8cc54ed878f7d313bcf00586edceae4ff712c837faaa5ddab0ad378b3
\ No newline at end of file
diff --git a/tests/test_mgxs_library_nuclides/inputs_true.dat b/tests/test_mgxs_library_nuclides/inputs_true.dat
index a15bbee4c..f3c25d4d5 100644
--- a/tests/test_mgxs_library_nuclides/inputs_true.dat
+++ b/tests/test_mgxs_library_nuclides/inputs_true.dat
@@ -1 +1 @@
-e4a5f03ab6167e96462c4ef537533fe33b98d7878ae00824c5619356bda8d548b3c71af01ba8c88d5a9b46dd1471d331e6f678a164af922200f2ee3642be6340
\ No newline at end of file
+332fd9ff1ca576410ffc6c0f3f03c00618fc863509dc3725f2f3a82134e2400de9c1edf2adc68cb8bce528789094f8eb468371e65cbc13efe76d76467ef291d9
\ No newline at end of file
diff --git a/tests/test_multipole/inputs_true.dat b/tests/test_multipole/inputs_true.dat
index 801536d07..f99b29e8e 100644
--- a/tests/test_multipole/inputs_true.dat
+++ b/tests/test_multipole/inputs_true.dat
@@ -1 +1 @@
-c727431ebef7a5987dade28f4cd940c566142f97b5ce01fbf9343d680caf9056623f0fac550db64f8f1043fa2cd8230155cfcbbcaffd1ae92cede723974596d7
\ No newline at end of file
+54044104d26e9aa90abcdb62290b598bd6ef0d46c3a9e509726ae7b20a7155471edd3e942b71f07b5c855ac1e451d58913a2f43fa971a8c4d56e569ae3b401ed
\ No newline at end of file
diff --git a/tests/test_multipole/test_multipole.py b/tests/test_multipole/test_multipole.py
index bd6822bdf..812f5b6d0 100644
--- a/tests/test_multipole/test_multipole.py
+++ b/tests/test_multipole/test_multipole.py
@@ -24,7 +24,7 @@ class MultipoleTestHarness(PyAPITestHarness):
         dense_fuel.add_nuclide('U235', 1.0)
 
         mats_file = openmc.Materials([moderator, dense_fuel])
-        mats_file.default_xs = '71c'
+        mats_file.default_temperature = '294K'
         mats_file.export_to_xml()
 
 
diff --git a/tests/test_natural_element/materials.xml b/tests/test_natural_element/materials.xml
index 60d60b81f..543b5351d 100644
--- a/tests/test_natural_element/materials.xml
+++ b/tests/test_natural_element/materials.xml
@@ -3,7 +3,7 @@
 
   <!-- pu-met-fast-021 case 2 -->
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Plutonium -->
   <material id="1">
diff --git a/tests/test_output/materials.xml b/tests/test_output/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_output/materials.xml
+++ b/tests/test_output/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_particle_restart_eigval/materials.xml b/tests/test_particle_restart_eigval/materials.xml
index 5ff4b736f..301efd2bd 100644
--- a/tests/test_particle_restart_eigval/materials.xml
+++ b/tests/test_particle_restart_eigval/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="20.0" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_particle_restart_fixed/materials.xml b/tests/test_particle_restart_fixed/materials.xml
index f132f9763..95afc3999 100644
--- a/tests/test_particle_restart_fixed/materials.xml
+++ b/tests/test_particle_restart_fixed/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="1.4" units="g/cc" />
-    <nuclide name="B10" xs="71c" ao="1.0" />
+    <nuclide name="B10" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_periodic/test_periodic.py b/tests/test_periodic/test_periodic.py
index 026071104..3883654c1 100644
--- a/tests/test_periodic/test_periodic.py
+++ b/tests/test_periodic/test_periodic.py
@@ -13,7 +13,7 @@ class PeriodicTest(PyAPITestHarness):
         water = openmc.Material(1)
         water.add_nuclide('H1', 2.0)
         water.add_nuclide('O16', 1.0)
-        water.add_s_alpha_beta('c_H_in_H2O', '71t')
+        water.add_s_alpha_beta('c_H_in_H2O')
         water.set_density('g/cc', 1.0)
 
         fuel = openmc.Material(2)
@@ -21,7 +21,7 @@ class PeriodicTest(PyAPITestHarness):
         fuel.set_density('g/cc', 4.5)
 
         materials = openmc.Materials((water, fuel))
-        materials.default_xs = '71c'
+        materials.default_temperature = '294K'
         materials.export_to_xml()
 
         # Define geometry
diff --git a/tests/test_plot/materials.xml b/tests/test_plot/materials.xml
index 826f670a4..0d5ee77ce 100644
--- a/tests/test_plot/materials.xml
+++ b/tests/test_plot/materials.xml
@@ -1,19 +1,21 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
   <material id="2">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
   <material id="3">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_ptables_off/materials.xml b/tests/test_ptables_off/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_ptables_off/materials.xml
+++ b/tests/test_ptables_off/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_quadric_surfaces/materials.xml b/tests/test_quadric_surfaces/materials.xml
index 606253bec..baf523b34 100644
--- a/tests/test_quadric_surfaces/materials.xml
+++ b/tests/test_quadric_surfaces/materials.xml
@@ -1,10 +1,12 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U238" xs="71c" ao="1.0" />
-    <nuclide name="U235" xs="71c" ao="0.06" />
+    <nuclide name="U238" ao="1.0" />
+    <nuclide name="U235" ao="0.06" />
   </material>
 
 </materials>
diff --git a/tests/test_reflective_plane/materials.xml b/tests/test_reflective_plane/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_reflective_plane/materials.xml
+++ b/tests/test_reflective_plane/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_rotation/materials.xml b/tests/test_rotation/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_rotation/materials.xml
+++ b/tests/test_rotation/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_salphabeta/materials.xml b/tests/test_salphabeta/materials.xml
index 2bc401e49..0d250e7b4 100644
--- a/tests/test_salphabeta/materials.xml
+++ b/tests/test_salphabeta/materials.xml
@@ -1,20 +1,20 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <material id="1">
     <density value="4.5" units="g/cc" />
     <nuclide name="U235" ao="1.0" />
     <nuclide name="H1" ao="1.0" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <material id="2">
     <density value="4.5" units="g/cc" />
     <nuclide name="U235" ao="1.0" />
     <nuclide name="C0" ao="1.0" />
-    <sab name="c_Graphite" xs="71t" />
+    <sab name="c_Graphite" />
   </material>
 
   <material id="3">
@@ -22,8 +22,8 @@
     <nuclide name="U235" ao="1.0" />
     <nuclide name="Be9" ao="1.0" />
     <nuclide name="O16" ao="1.0" />
-    <sab name="c_Be_in_BeO" xs="71t" />
-    <sab name="c_O_in_BeO" xs="71t" />
+    <sab name="c_Be_in_BeO" />
+    <sab name="c_O_in_BeO" />
   </material>
 
   <material id="4">
@@ -36,8 +36,8 @@
     <nuclide name="Zr96"  ao="0.05" />
     <nuclide name="U235"  ao="0.1" />
     <nuclide name="U238"  ao="0.15" />
-    <sab name="c_Zr_in_ZrH" xs="71t" />
-    <sab name="c_H_in_ZrH" xs="71t" />
+    <sab name="c_Zr_in_ZrH" />
+    <sab name="c_H_in_ZrH" />
   </material>
 
 </materials>
diff --git a/tests/test_score_current/materials.xml b/tests/test_score_current/materials.xml
index f5a9e61be..bead58f8b 100644
--- a/tests/test_score_current/materials.xml
+++ b/tests/test_score_current/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Fuel composition -->
   <material id="1">
@@ -59,7 +59,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Hot borated water -->
@@ -69,7 +69,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- RPV Composition -->
@@ -128,7 +128,7 @@
     <nuclide name="Cr52" wo="0.145407678031" />
     <nuclide name="Cr53" wo="0.016806340306" />
     <nuclide name="Cr54" wo="0.004261520857" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Upper radial reflector / Top plate region -->
@@ -155,7 +155,7 @@
     <nuclide name="Cr52" wo="0.146766614995" />
     <nuclide name="Cr53" wo="0.01696340737" />
     <nuclide name="Cr54" wo="0.004301347765" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom plate region -->
@@ -182,7 +182,7 @@
     <nuclide name="Cr52" wo="0.157390026871" />
     <nuclide name="Cr53" wo="0.018191270146" />
     <nuclide name="Cr54" wo="0.004612692337" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom nozzle region -->
@@ -209,7 +209,7 @@
     <nuclide name="Cr52" wo="0.124142524198" />
     <nuclide name="Cr53" wo="0.014348496148" />
     <nuclide name="Cr54" wo="0.003638294506" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top nozzle region -->
@@ -236,7 +236,7 @@
     <nuclide name="Cr52" wo="0.107931450781" />
     <nuclide name="Cr53" wo="0.012474806806" />
     <nuclide name="Cr54" wo="0.003163190107" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top of Fuel Assemblies -->
@@ -251,7 +251,7 @@
     <nuclide name="Zr92" wo="0.14759527104" />
     <nuclide name="Zr94" wo="0.15280552077" />
     <nuclide name="Zr96" wo="0.02511169542" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom of Fuel Assemblies -->
@@ -266,7 +266,7 @@
     <nuclide name="Zr92" wo="0.1274914944" />
     <nuclide name="Zr94" wo="0.1319920622" />
     <nuclide name="Zr96" wo="0.0216912612" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/tests/test_seed/materials.xml b/tests/test_seed/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_seed/materials.xml
+++ b/tests/test_seed/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_source/test_source.py b/tests/test_source/test_source.py
index 09a13efaa..f83e39974 100644
--- a/tests/test_source/test_source.py
+++ b/tests/test_source/test_source.py
@@ -13,9 +13,9 @@ import openmc
 
 class SourceTestHarness(PyAPITestHarness):
     def _build_inputs(self):
-        mat1 = openmc.Material(material_id=1)
+        mat1 = openmc.Material(material_id=1, temperature='294K')
         mat1.set_density('g/cm3', 4.5)
-        mat1.add_nuclide(openmc.Nuclide('U235', '71c'), 1.0)
+        mat1.add_nuclide(openmc.Nuclide('U235'), 1.0)
         materials = openmc.Materials([mat1])
         materials.export_to_xml()
 
diff --git a/tests/test_source_file/materials.xml b/tests/test_source_file/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_source_file/materials.xml
+++ b/tests/test_source_file/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_sourcepoint_batch/materials.xml b/tests/test_sourcepoint_batch/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_sourcepoint_batch/materials.xml
+++ b/tests/test_sourcepoint_batch/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_sourcepoint_interval/materials.xml b/tests/test_sourcepoint_interval/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_sourcepoint_interval/materials.xml
+++ b/tests/test_sourcepoint_interval/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_sourcepoint_latest/materials.xml b/tests/test_sourcepoint_latest/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_sourcepoint_latest/materials.xml
+++ b/tests/test_sourcepoint_latest/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_sourcepoint_restart/materials.xml b/tests/test_sourcepoint_restart/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_sourcepoint_restart/materials.xml
+++ b/tests/test_sourcepoint_restart/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_statepoint_batch/materials.xml b/tests/test_statepoint_batch/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_statepoint_batch/materials.xml
+++ b/tests/test_statepoint_batch/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_statepoint_interval/materials.xml b/tests/test_statepoint_interval/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_statepoint_interval/materials.xml
+++ b/tests/test_statepoint_interval/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_statepoint_restart/materials.xml b/tests/test_statepoint_restart/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_statepoint_restart/materials.xml
+++ b/tests/test_statepoint_restart/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_statepoint_sourcesep/materials.xml b/tests/test_statepoint_sourcesep/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_statepoint_sourcesep/materials.xml
+++ b/tests/test_statepoint_sourcesep/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_survival_biasing/materials.xml b/tests/test_survival_biasing/materials.xml
index facad016b..03b2162b3 100644
--- a/tests/test_survival_biasing/materials.xml
+++ b/tests/test_survival_biasing/materials.xml
@@ -1,10 +1,12 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="19.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="2.0" />
-    <nuclide name="U238" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="2.0" />
+    <nuclide name="U238" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_tallies/inputs_true.dat b/tests/test_tallies/inputs_true.dat
index f5390eea1..196925c38 100644
--- a/tests/test_tallies/inputs_true.dat
+++ b/tests/test_tallies/inputs_true.dat
@@ -1 +1 @@
-1bef757d276362fdcd9405096b4cdcbd894f9215ed406493486a45193729be446c9a12242c887f89b6e209ec5beaaacb04dee2fd61e72b4f5c6a8712b776ed6e
\ No newline at end of file
+11adb9111f20950e28b1c1929ee4ca0c9a6b2524de89bef44a495b2fe8cda3a2acac9e87d64ddb5eba591c8d22289956cb1f024d31e05da3c9a4162b8c589d85
\ No newline at end of file
diff --git a/tests/test_tally_aggregation/inputs_true.dat b/tests/test_tally_aggregation/inputs_true.dat
index 9c7978755..fa61e20b7 100644
--- a/tests/test_tally_aggregation/inputs_true.dat
+++ b/tests/test_tally_aggregation/inputs_true.dat
@@ -1 +1 @@
-67daf0d74cddb40ecbbc7e3793a3302866adcb1617fe2dc454dd161c06105e65027523f5e5954d80b961ba6c6abf14114b8be5c4d5b7682eaddffc1288d3e7c8
\ No newline at end of file
+bc17ba12ee5de7e6b0226e589be9044af725ff4e27683b765a9c75e5629176b5ca51d1e0306028ae90185d64644babf9ac22e4753f092b4b836790f4e162f9d0
\ No newline at end of file
diff --git a/tests/test_tally_arithmetic/inputs_true.dat b/tests/test_tally_arithmetic/inputs_true.dat
index b56c17b6b..56798828c 100644
--- a/tests/test_tally_arithmetic/inputs_true.dat
+++ b/tests/test_tally_arithmetic/inputs_true.dat
@@ -1 +1 @@
-c8772a174e2162030f0315a318991085f1a5c0b054883a5f071d520e34f9ecf7d309f25700067bea8685e2b6324a19a003bd6f6ab38161ee87c95257b5a6ae69
\ No newline at end of file
+6b59ea3a0dc0d25c590f724b8c051a54e8d7836467ba31b7da72b0574398e6c73160a180524952ea983b0e7a7de776d2d7102d280d5a4e7e3624bd76f6f42a09
\ No newline at end of file
diff --git a/tests/test_tally_assumesep/materials.xml b/tests/test_tally_assumesep/materials.xml
index f5a9e61be..bead58f8b 100644
--- a/tests/test_tally_assumesep/materials.xml
+++ b/tests/test_tally_assumesep/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Fuel composition -->
   <material id="1">
@@ -59,7 +59,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Hot borated water -->
@@ -69,7 +69,7 @@
     <nuclide name="O16" ao="1.0" />
     <nuclide name="B10" ao="6.490e-4" />
     <nuclide name="B11" ao="2.689e-3" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- RPV Composition -->
@@ -128,7 +128,7 @@
     <nuclide name="Cr52" wo="0.145407678031" />
     <nuclide name="Cr53" wo="0.016806340306" />
     <nuclide name="Cr54" wo="0.004261520857" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Upper radial reflector / Top plate region -->
@@ -155,7 +155,7 @@
     <nuclide name="Cr52" wo="0.146766614995" />
     <nuclide name="Cr53" wo="0.01696340737" />
     <nuclide name="Cr54" wo="0.004301347765" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom plate region -->
@@ -182,7 +182,7 @@
     <nuclide name="Cr52" wo="0.157390026871" />
     <nuclide name="Cr53" wo="0.018191270146" />
     <nuclide name="Cr54" wo="0.004612692337" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom nozzle region -->
@@ -209,7 +209,7 @@
     <nuclide name="Cr52" wo="0.124142524198" />
     <nuclide name="Cr53" wo="0.014348496148" />
     <nuclide name="Cr54" wo="0.003638294506" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top nozzle region -->
@@ -236,7 +236,7 @@
     <nuclide name="Cr52" wo="0.107931450781" />
     <nuclide name="Cr53" wo="0.012474806806" />
     <nuclide name="Cr54" wo="0.003163190107" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Top of Fuel Assemblies -->
@@ -251,7 +251,7 @@
     <nuclide name="Zr92" wo="0.14759527104" />
     <nuclide name="Zr94" wo="0.15280552077" />
     <nuclide name="Zr96" wo="0.02511169542" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
   <!-- Bottom of Fuel Assemblies -->
@@ -266,7 +266,7 @@
     <nuclide name="Zr92" wo="0.1274914944" />
     <nuclide name="Zr94" wo="0.1319920622" />
     <nuclide name="Zr96" wo="0.0216912612" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 </materials>
diff --git a/tests/test_tally_nuclides/materials.xml b/tests/test_tally_nuclides/materials.xml
index e9667b41f..5ac4f6942 100644
--- a/tests/test_tally_nuclides/materials.xml
+++ b/tests/test_tally_nuclides/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Plutonium -->
   <material id="1">
diff --git a/tests/test_tally_slice_merge/inputs_true.dat b/tests/test_tally_slice_merge/inputs_true.dat
index 16d11b6d2..a40c0a01d 100644
--- a/tests/test_tally_slice_merge/inputs_true.dat
+++ b/tests/test_tally_slice_merge/inputs_true.dat
@@ -1 +1 @@
-a17354ce54bcb5ce93e861ae95fd932c45fe60c733d999aa180d5dee636f43130fac5b003c615e23c65d44fe55f376ef4c86596b78603ab217d7e37fd694074d
\ No newline at end of file
+6d9ebab08ccce003e6128c6346ffd80e69a957fab15e9a0e211771efa68b24f276e62781f8471c72072f9017380d7e821c38002c03689993efed45db9590c039
\ No newline at end of file
diff --git a/tests/test_trace/materials.xml b/tests/test_trace/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_trace/materials.xml
+++ b/tests/test_trace/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_track_output/materials.xml b/tests/test_track_output/materials.xml
index 017797aa1..f31f61fc3 100644
--- a/tests/test_track_output/materials.xml
+++ b/tests/test_track_output/materials.xml
@@ -1,95 +1,97 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
 <!-- material 1: Water with 1511 PPM -->
   <material id="1">
     <density value="0.99823" units="g/cc" />
-    <nuclide name="H1"  xs="71c" ao="6.6737E-002" />
-    <nuclide name="O16" xs="71c" ao="3.3369E-002" />
-    <nuclide name="B10" xs="71c" ao="1.6769E-005" />
-    <nuclide name="B11" xs="71c" ao="6.7497E-005" />
-    <sab name="c_H_in_H2O" xs="71t" />
+    <nuclide name="H1"  ao="6.6737E-002" />
+    <nuclide name="O16" ao="3.3369E-002" />
+    <nuclide name="B10" ao="1.6769E-005" />
+    <nuclide name="B11" ao="6.7497E-005" />
+    <sab name="c_H_in_H2O" />
   </material>
 
 <!-- material 2: Fuel (2.459 w/o with B-10 for impurities) -->
   <material id="2">
     <density value="10.24" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="5.6868E-004" />
-<!--    <nuclide name="U234" xs="71c" ao="4.5689E-006" />  -->
-    <nuclide name="U238" xs="71c" ao="2.2268E-002" />
-    <nuclide name="O16"  xs="71c" ao="4.5683E-002" />
-    <nuclide name="B10"  xs="71c" ao="2.6055E-007" />
+    <nuclide name="U235" ao="5.6868E-004" />
+<!--    <nuclide name="U234" ao="4.5689E-006" />  -->
+    <nuclide name="U238" ao="2.2268E-002" />
+    <nuclide name="O16"  ao="4.5683E-002" />
+    <nuclide name="B10"  ao="2.6055E-007" />
   </material>
 
   <!--               Zircaloy-4               -->
   <material id="3">
     <density value="  6.55" units="g/cc" />
-    <nuclide name="O16"  xs="71c" ao="3.0743e-04" />
-<!--    <nuclide name="O17"  xs="71c" ao="7.4887e-07" />-->
-<!--    <nuclide name="Cr50"  xs="71c" ao="3.2962e-06" />-->
-<!--    <nuclide name="Cr52"  xs="71c" ao="6.3564e-05" />-->
-<!--    <nuclide name="Cr53"  xs="71c" ao="7.2076e-06" />-->
-<!--    <nuclide name="Cr54"  xs="71c" ao="1.7941e-06" />-->
-<!--    <nuclide name="Fe54"  xs="71c" ao="8.6699e-06" />-->
-<!--    <nuclide name="Fe56"  xs="71c" ao="1.3610e-04" />-->
-<!--    <nuclide name="Fe57"  xs="71c" ao="3.1431e-06" />-->
-<!--    <nuclide name="Fe58"  xs="71c" ao="4.1829e-07" />-->
-    <nuclide name="Zr90"  xs="71c" ao="2.1827e-02" />
-    <nuclide name="Zr91"  xs="71c" ao="4.7600e-03" />
-    <nuclide name="Zr92"  xs="71c" ao="7.2758e-03" />
-    <nuclide name="Zr94"  xs="71c" ao="7.3734e-03" />
-    <nuclide name="Zr96"  xs="71c" ao="1.1879e-03" />
-<!--    <nuclide name="Sn112"  xs="71c" ao="4.6735e-06" />-->
-<!--    <nuclide name="Sn114"  xs="71c" ao="3.1799e-06" />-->
-<!--    <nuclide name="Sn115"  xs="71c" ao="1.6381e-06" />-->
-<!--    <nuclide name="Sn116"  xs="71c" ao="7.0055e-05" />-->
-<!--    <nuclide name="Sn117"  xs="71c" ao="3.7003e-05" />-->
-<!--    <nuclide name="Sn118"  xs="71c" ao="1.1669e-04" />-->
-<!--    <nuclide name="Sn119"  xs="71c" ao="4.1387e-05" />-->
-<!--    <nuclide name="Sn120"  xs="71c" ao="1.5697e-04" />-->
-<!--    <nuclide name="Sn122"  xs="71c" ao="2.2308e-05" />-->
-<!--    <nuclide name="Sn124"  xs="71c" ao="2.7897e-05" />-->
+    <nuclide name="O16"  ao="3.0743e-04" />
+<!--    <nuclide name="O17"  ao="7.4887e-07" />-->
+<!--    <nuclide name="Cr50"  ao="3.2962e-06" />-->
+<!--    <nuclide name="Cr52"  ao="6.3564e-05" />-->
+<!--    <nuclide name="Cr53"  ao="7.2076e-06" />-->
+<!--    <nuclide name="Cr54"  ao="1.7941e-06" />-->
+<!--    <nuclide name="Fe54"  ao="8.6699e-06" />-->
+<!--    <nuclide name="Fe56"  ao="1.3610e-04" />-->
+<!--    <nuclide name="Fe57"  ao="3.1431e-06" />-->
+<!--    <nuclide name="Fe58"  ao="4.1829e-07" />-->
+    <nuclide name="Zr90"  ao="2.1827e-02" />
+    <nuclide name="Zr91"  ao="4.7600e-03" />
+    <nuclide name="Zr92"  ao="7.2758e-03" />
+    <nuclide name="Zr94"  ao="7.3734e-03" />
+    <nuclide name="Zr96"  ao="1.1879e-03" />
+<!--    <nuclide name="Sn112"  ao="4.6735e-06" />-->
+<!--    <nuclide name="Sn114"  ao="3.1799e-06" />-->
+<!--    <nuclide name="Sn115"  ao="1.6381e-06" />-->
+<!--    <nuclide name="Sn116"  ao="7.0055e-05" />-->
+<!--    <nuclide name="Sn117"  ao="3.7003e-05" />-->
+<!--    <nuclide name="Sn118"  ao="1.1669e-04" />-->
+<!--    <nuclide name="Sn119"  ao="4.1387e-05" />-->
+<!--    <nuclide name="Sn120"  ao="1.5697e-04" />-->
+<!--    <nuclide name="Sn122"  ao="2.2308e-05" />-->
+<!--    <nuclide name="Sn124"  ao="2.7897e-05" />-->
   </material>
 
 <!-- material 3: Fuel Aluminum 6061 cladding -->
 <!--  <material id="3">-->
 <!--    <density value="2.5052" units="g/cc" />-->
-<!--    <nuclide name="Al27" xs="71c" ao="5.3985e-02" />-->
-<!--    <nuclide name="Mn55" xs="71c" ao="4.1191e-05" />-->
-<!--    <nuclide name="Mg24" xs="71c" ao="4.9031e-04" />-->
-<!--    <nuclide name="Mg25" xs="71c" ao="6.2072e-05" />-->
-<!--    <nuclide name="Mg26" xs="71c" ao="6.8341e-05" />-->
-<!--    <nuclide name="Si28" xs="71c" ao="2.9726e-04" />-->
-<!--    <nuclide name="Si29" xs="71c" ao="1.5094e-05" />-->
-<!--    <nuclide name="Si30" xs="71c" ao="9.9499e-06" />-->
-<!--    <nuclide name="Cr50" xs="71c" ao="2.5214e-06" />-->
-<!--    <nuclide name="Cr52" xs="71c" ao="4.8622e-05" />-->
-<!--    <nuclide name="Cr53" xs="71c" ao="5.5133e-06" />-->
-<!--    <nuclide name="Cr54" xs="71c" ao="1.3724e-06" />-->
-<!--    <nuclide name="Fe54" xs="71c" ao="1.1053e-05" />-->
-<!--    <nuclide name="Fe56" xs="71c" ao="1.7351e-04" />-->
-<!--    <nuclide name="Fe57" xs="71c" ao="4.0070e-06" />-->
-<!--    <nuclide name="Fe58" xs="71c" ao="5.3326e-07" />-->
-<!--    <nuclide name="Ti46" xs="71c" ao="3.8992e-06" />-->
-<!--    <nuclide name="Ti47" xs="71c" ao="3.5164e-06" />-->
-<!--    <nuclide name="Ti48" xs="71c" ao="3.4842e-05" />-->
-<!--    <nuclide name="Ti49" xs="71c" ao="2.5569e-06" />-->
-<!--    <nuclide name="Ti50" xs="71c" ao="2.4482e-06" />-->
-<!--    <nuclide name="Cu63" xs="71c" ao="4.1054e-05" />-->
-<!--    <nuclide name="Cu65" xs="71c" ao="1.8299e-05" />-->
+<!--    <nuclide name="Al27" ao="5.3985e-02" />-->
+<!--    <nuclide name="Mn55" ao="4.1191e-05" />-->
+<!--    <nuclide name="Mg24" ao="4.9031e-04" />-->
+<!--    <nuclide name="Mg25" ao="6.2072e-05" />-->
+<!--    <nuclide name="Mg26" ao="6.8341e-05" />-->
+<!--    <nuclide name="Si28" ao="2.9726e-04" />-->
+<!--    <nuclide name="Si29" ao="1.5094e-05" />-->
+<!--    <nuclide name="Si30" ao="9.9499e-06" />-->
+<!--    <nuclide name="Cr50" ao="2.5214e-06" />-->
+<!--    <nuclide name="Cr52" ao="4.8622e-05" />-->
+<!--    <nuclide name="Cr53" ao="5.5133e-06" />-->
+<!--    <nuclide name="Cr54" ao="1.3724e-06" />-->
+<!--    <nuclide name="Fe54" ao="1.1053e-05" />-->
+<!--    <nuclide name="Fe56" ao="1.7351e-04" />-->
+<!--    <nuclide name="Fe57" ao="4.0070e-06" />-->
+<!--    <nuclide name="Fe58" ao="5.3326e-07" />-->
+<!--    <nuclide name="Ti46" ao="3.8992e-06" />-->
+<!--    <nuclide name="Ti47" ao="3.5164e-06" />-->
+<!--    <nuclide name="Ti48" ao="3.4842e-05" />-->
+<!--    <nuclide name="Ti49" ao="2.5569e-06" />-->
+<!--    <nuclide name="Ti50" ao="2.4482e-06" />-->
+<!--    <nuclide name="Cu63" ao="4.1054e-05" />-->
+<!--    <nuclide name="Cu65" ao="1.8299e-05" />-->
 <!--  </material>-->
 
 <!-- material 4: Control Rod Material -->
   <material id="4">
     <density value="2.2442" units="g/cc" />
-    <nuclide name="B10"  xs="71c" ao="9.7491e-4" />
-    <nuclide name="B11"  xs="71c" ao="3.9241e-3" />
-    <nuclide name="O16"  xs="71c" ao="4.4829e-2" />
-<!--    <nuclide name="Na23" xs="71c" ao="1.7444e-3" />-->
-<!--    <nuclide name="Al27" xs="71c" ao="1.0018e-3" />-->
-<!--    <nuclide name="Si28" xs="71c" ao="1.6884e-02" />-->
-<!--    <nuclide name="Si29" xs="71c" ao="8.5730e-04" />-->
-<!--    <nuclide name="Si30" xs="71c" ao="5.6513e-04" />-->
+    <nuclide name="B10"  ao="9.7491e-4" />
+    <nuclide name="B11"  ao="3.9241e-3" />
+    <nuclide name="O16"  ao="4.4829e-2" />
+<!--    <nuclide name="Na23" ao="1.7444e-3" />-->
+<!--    <nuclide name="Al27" ao="1.0018e-3" />-->
+<!--    <nuclide name="Si28" ao="1.6884e-02" />-->
+<!--    <nuclide name="Si29" ao="8.5730e-04" />-->
+<!--    <nuclide name="Si30" ao="5.6513e-04" />-->
   </material>
-  
+
 </materials>
diff --git a/tests/test_translation/materials.xml b/tests/test_translation/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_translation/materials.xml
+++ b/tests/test_translation/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_trigger_batch_interval/materials.xml b/tests/test_trigger_batch_interval/materials.xml
index e9667b41f..5ac4f6942 100644
--- a/tests/test_trigger_batch_interval/materials.xml
+++ b/tests/test_trigger_batch_interval/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Plutonium -->
   <material id="1">
diff --git a/tests/test_trigger_no_batch_interval/materials.xml b/tests/test_trigger_no_batch_interval/materials.xml
index e9667b41f..5ac4f6942 100644
--- a/tests/test_trigger_no_batch_interval/materials.xml
+++ b/tests/test_trigger_no_batch_interval/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Plutonium -->
   <material id="1">
diff --git a/tests/test_trigger_no_status/materials.xml b/tests/test_trigger_no_status/materials.xml
index e9667b41f..5ac4f6942 100644
--- a/tests/test_trigger_no_status/materials.xml
+++ b/tests/test_trigger_no_status/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Plutonium -->
   <material id="1">
diff --git a/tests/test_trigger_tallies/materials.xml b/tests/test_trigger_tallies/materials.xml
index e9667b41f..5ac4f6942 100644
--- a/tests/test_trigger_tallies/materials.xml
+++ b/tests/test_trigger_tallies/materials.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materials>
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Plutonium -->
   <material id="1">
diff --git a/tests/test_triso/test_triso.py b/tests/test_triso/test_triso.py
index 9a8fb0c3b..04bd1322a 100644
--- a/tests/test_triso/test_triso.py
+++ b/tests/test_triso/test_triso.py
@@ -27,12 +27,12 @@ class TRISOTestHarness(PyAPITestHarness):
         porous_carbon = openmc.Material()
         porous_carbon.set_density('g/cm3', 1.0)
         porous_carbon.add_nuclide('C0', 1.0)
-        porous_carbon.add_s_alpha_beta('c_Graphite', '71t')
+        porous_carbon.add_s_alpha_beta('c_Graphite')
 
         ipyc = openmc.Material()
         ipyc.set_density('g/cm3', 1.90)
         ipyc.add_nuclide('C0', 1.0)
-        ipyc.add_s_alpha_beta('c_Graphite', '71t')
+        ipyc.add_s_alpha_beta('c_Graphite')
 
         sic = openmc.Material()
         sic.set_density('g/cm3', 3.20)
@@ -42,12 +42,12 @@ class TRISOTestHarness(PyAPITestHarness):
         opyc = openmc.Material()
         opyc.set_density('g/cm3', 1.87)
         opyc.add_nuclide('C0', 1.0)
-        opyc.add_s_alpha_beta('c_Graphite', '71t')
+        opyc.add_s_alpha_beta('c_Graphite')
 
         graphite = openmc.Material()
         graphite.set_density('g/cm3', 1.1995)
         graphite.add_nuclide('C0', 1.0)
-        graphite.add_s_alpha_beta('c_Graphite', '71t')
+        graphite.add_s_alpha_beta('c_Graphite')
 
         # Create TRISO particles
         spheres = [openmc.Sphere(R=r*1e-4)
@@ -108,7 +108,7 @@ class TRISOTestHarness(PyAPITestHarness):
         settings.export_to_xml()
 
         mats = openmc.Materials([fuel, porous_carbon, ipyc, sic, opyc, graphite])
-        mats.default_xs = '71c'
+        mats.default_temperature = '294K'
         mats.export_to_xml()
 
 
diff --git a/tests/test_uniform_fs/materials.xml b/tests/test_uniform_fs/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_uniform_fs/materials.xml
+++ b/tests/test_uniform_fs/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_union_energy_grids/materials.xml b/tests/test_union_energy_grids/materials.xml
index ed9b38d90..2946a8d60 100644
--- a/tests/test_union_energy_grids/materials.xml
+++ b/tests/test_union_energy_grids/materials.xml
@@ -1,11 +1,13 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
-    <nuclide name="H1" xs="71c" ao="0.5" />
-    <nuclide name="C0" xs="71c" ao="0.5" />
+    <nuclide name="U235" ao="1.0" />
+    <nuclide name="H1" ao="0.5" />
+    <nuclide name="C0" ao="0.5" />
   </material>
 
 </materials>
diff --git a/tests/test_universe/materials.xml b/tests/test_universe/materials.xml
index 23d7f969d..37cfcdc6e 100644
--- a/tests/test_universe/materials.xml
+++ b/tests/test_universe/materials.xml
@@ -1,9 +1,11 @@
 <?xml version="1.0"?>
 <materials>
 
+  <default_temperature>294K</default_temperature>
+
   <material id="1">
     <density value="4.5" units="g/cc" />
-    <nuclide name="U235" xs="71c" ao="1.0" />
+    <nuclide name="U235" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_void/materials.xml b/tests/test_void/materials.xml
index 4768bad0b..2a578e0ed 100644
--- a/tests/test_void/materials.xml
+++ b/tests/test_void/materials.xml
@@ -3,7 +3,7 @@
 
   <!-- pu-met-fast-019 -->
 
-  <default_xs>71c</default_xs>
+  <default_temperature>294K</default_temperature>
 
   <!-- Plutonium -->
   <material id="1">
@@ -41,7 +41,7 @@
     <nuclide name="Fe56" ao="4.6739e-05" />
     <nuclide name="Fe57" ao="1.0794e-06" />
     <nuclide name="Fe58" ao="1.4365e-07" />
-    <sab name="c_Be" xs="71t" />
+    <sab name="c_Be" />
   </material>
 
   <!-- Steel Diaphragm and Steel Shaft -->
diff --git a/tests/test_volume_calc/test_volume_calc.py b/tests/test_volume_calc/test_volume_calc.py
index e2c3eba79..656f4654a 100644
--- a/tests/test_volume_calc/test_volume_calc.py
+++ b/tests/test_volume_calc/test_volume_calc.py
@@ -15,7 +15,7 @@ class VolumeTest(PyAPITestHarness):
         water.add_nuclide('H1', 2.0)
         water.add_nuclide('O16', 1.0)
         water.add_nuclide('B10', 0.0001)
-        water.add_s_alpha_beta('c_H_in_H2O', '71t')
+        water.add_s_alpha_beta('c_H_in_H2O')
         water.set_density('g/cc', 1.0)
 
         fuel = openmc.Material(2)
@@ -24,7 +24,7 @@ class VolumeTest(PyAPITestHarness):
         fuel.set_density('g/cc', 4.5)
 
         materials = openmc.Materials((water, fuel))
-        materials.default_xs = '71c'
+        materials.default_temperature = '294K'
         materials.export_to_xml()
 
         cyl = openmc.ZCylinder(1, R=1.0, boundary_type='vacuum')