diff --git a/openmc/data/thermal.py b/openmc/data/thermal.py
index 58c5276052..bbdb12dad2 100644
--- a/openmc/data/thermal.py
+++ b/openmc/data/thermal.py
@@ -226,7 +226,7 @@ class ThermalScattering(EqualityMixin):
         # Write basic data
         g = f.create_group(self.name)
         g.attrs['atomic_weight_ratio'] = self.atomic_weight_ratio
-        g.attrs['nuclides'] = np.string_(self.nuclides)
+        g.attrs['nuclides'] = np.array(self.nuclides, dtype='S')
         g.attrs['secondary_mode'] = np.string_(self.secondary_mode)
         ktg = g.create_group('kTs')
         for i, temperature in enumerate(self.temperatures):
diff --git a/openmc/material.py b/openmc/material.py
index 2b52995738..f56af485a4 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -724,32 +724,14 @@ class Materials(cv.CheckedList):
     materials : Iterable of openmc.Material
         Materials to add to the collection
 
-    Attributes
-    ----------
-    default_temperature : str
-        The default temperature identifier applied to a material when none is
-        specified. The units are in Kelvin and the temperature rounded to the
-        nearest integer. For example, a tempreature of 293.6K would be
-        provided as '294K'
-
     """
 
     def __init__(self, materials=None):
         super(Materials, self).__init__(Material, 'materials collection')
-        self._default_temperature = None
         self._materials_file = ET.Element("materials")
         if materials is not None:
             self += materials
 
-    @property
-    def default_temperature(self):
-        return self._default_temperature
-
-    @default_temperature.setter
-    def default_temperature(self, temperature):
-        cv.check_type('default_temperature', temperature, basestring)
-        self._default_temperature = temperature
-
     def add_material(self, material):
         """Append material to collection
 
@@ -831,11 +813,6 @@ class Materials(cv.CheckedList):
             material.make_isotropic_in_lab()
 
     def _create_material_subelements(self):
-        if self._default_temperature is not None:
-            subelement = ET.SubElement(self._materials_file,
-                                       "default_temperature")
-            subelement.text = self._default_temperature
-
         for material in self:
             xml_element = material.get_material_xml()
             self._materials_file.append(xml_element)
diff --git a/src/hdf5_interface.F90 b/src/hdf5_interface.F90
index 415ec55c9e..136628162c 100644
--- a/src/hdf5_interface.F90
+++ b/src/hdf5_interface.F90
@@ -2468,7 +2468,6 @@ contains
     call h5aget_type_f(attr_id, filetype, hdf5_err)
     call h5tget_size_f(filetype, size, hdf5_err)
     if (size > len(buffer(1)) + 1) then
-      print *, size, len(buffer(1))
       call fatal_error("Character buffer is not long enough to &
            &read HDF5 string array.")
     end if
diff --git a/tests/input_set.py b/tests/input_set.py
index e409fba58f..94576acf0d 100644
--- a/tests/input_set.py
+++ b/tests/input_set.py
@@ -271,7 +271,6 @@ class InputSet(object):
         bot_fa.add_s_alpha_beta('c_H_in_H2O')
 
         # Define the materials file.
-        self.materials.default_temperature = '294K'
         self.materials += (fuel, clad, cold_water, hot_water, rpv_steel,
                            lower_rad_ref, upper_rad_ref, bot_plate,
                            bot_nozzle, top_nozzle, top_fa, bot_fa)
@@ -615,7 +614,6 @@ class PinCellInputSet(object):
         hot_water.add_s_alpha_beta('c_H_in_H2O')
 
         # Define the materials file.
-        self.materials.default_temperature = '294K'
         self.materials += (fuel, clad, hot_water)
 
         # Instantiate ZCylinder surfaces
@@ -717,7 +715,6 @@ class AssemblyInputSet(object):
         hot_water.add_s_alpha_beta('c_H_in_H2O')
 
         # Define the materials file.
-        self.materials.default_temperature = '294K'
         self.materials += (fuel, clad, hot_water)
 
         # Instantiate ZCylinder surfaces
@@ -845,7 +842,6 @@ class MGInputSet(InputSet):
         water.add_macroscopic(water_data)
 
         # Define the materials file.
-        self.materials.default_temperature = '294K'
         self.materials += (uo2, clad, water)
 
         # Define surfaces.
diff --git a/tests/test_asymmetric_lattice/inputs_true.dat b/tests/test_asymmetric_lattice/inputs_true.dat
index 997d74ba88..9d278724f8 100644
--- a/tests/test_asymmetric_lattice/inputs_true.dat
+++ b/tests/test_asymmetric_lattice/inputs_true.dat
@@ -1 +1 @@
-7b62ec28ffec0028dc07ed23b720ae3f97b00aa15b319dc3991d9f1f88fcae8bffc7ccd2385d2b848180a57120624061ff4fe10745a3187e3e64fee0faface8d
\ No newline at end of file
+dfb59bace10a91bb7ffc871d8ee87e91d94754bb8bb002ac6088f80fe0f480741c0489f74b753fc37158d0ff0f1368739ea60638b42083791311eefeac79168e
\ No newline at end of file
diff --git a/tests/test_distribmat/inputs_true.dat b/tests/test_distribmat/inputs_true.dat
index 2ba50f7e8c..d21da2f894 100644
--- a/tests/test_distribmat/inputs_true.dat
+++ b/tests/test_distribmat/inputs_true.dat
@@ -1 +1 @@
-dd0b1228d264dd3c24ca3082de9839080f727a137c77bed74b7637cc16d1564ce7500e3bb61a88224926f1d837079702f304247efdf9e52dedf779e17cd14550
\ 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 29c5d638f3..ec19176c49 100644
--- a/tests/test_distribmat/test_distribmat.py
+++ b/tests/test_distribmat/test_distribmat.py
@@ -29,7 +29,6 @@ class DistribmatTestHarness(PyAPITestHarness):
         light_fuel.add_nuclide('U235', 1.0)
 
         mats_file = openmc.Materials([moderator, dense_fuel, light_fuel])
-        mats_file.default_temperature = '294K'
         mats_file.export_to_xml()
 
 
diff --git a/tests/test_iso_in_lab/inputs_true.dat b/tests/test_iso_in_lab/inputs_true.dat
index 0298e581c6..310bccb139 100644
--- a/tests/test_iso_in_lab/inputs_true.dat
+++ b/tests/test_iso_in_lab/inputs_true.dat
@@ -1 +1 @@
-a84e601e6ba0891aaeaa37b1aa55076fecee598bb46be2b99dcdedab597b5d7e1731e2a0dc265df2ad6f475e33dae91a3cc27bc23d0c37be25a097ea83e74fd6
\ No newline at end of file
+4b3d0270a479e65579b305d1c2339b76971790bc7371c685efa6e2d341980fec301cf0859c34796ae04ae98aa01ab8b4905a8d8a3a916895c36d82ca6b58fb39
\ No newline at end of file
diff --git a/tests/test_mg_basic/inputs_true.dat b/tests/test_mg_basic/inputs_true.dat
index bfb0cc09e9..fad74ca827 100644
--- a/tests/test_mg_basic/inputs_true.dat
+++ b/tests/test_mg_basic/inputs_true.dat
@@ -1 +1 @@
-d90692c6bf8db3672d70103ded682326d7f14d416e79e18ec055bdeafe1dbc1dbe642e8410cad95bf247f27c907b10b1567127bd2868d466ce2586aacff0411f
\ No newline at end of file
+e843dbee8b989142d68e78f7a3e83309a9982c0127974ba4b6a58c823ce298e8fffc8828b48aa696f045818a2a80ef4003f5a191f33aacef7d7dd72c950855a6
\ No newline at end of file
diff --git a/tests/test_mg_tallies/inputs_true.dat b/tests/test_mg_tallies/inputs_true.dat
index c74d7759f7..e1f3385a43 100644
--- a/tests/test_mg_tallies/inputs_true.dat
+++ b/tests/test_mg_tallies/inputs_true.dat
@@ -1 +1 @@
-707285b77a091904a69720e78bf87a6779f2223c0fa2a3725353d00ca30f2624c7d53af016d78c7ad30b70a24bb53eda7dea2f592499b098f541591825b67143
\ No newline at end of file
+b607875dcaecb7110e396a62100182818b8b2853ec9921194b7ab00d6156373b01394ad8bd729babf7d258e6d9c599f6944c6857cd9d2f65ea98e245ee3cf010
\ 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 e48c50d0a0..7b30f91223 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 @@
-a33f770307b365103c5d71aa3e70deebd78d3a2fa90e88632641c1a40d64d19de0ce3c95c858aedf3beccc5de64cac434e1cd55b2b162ed315c78450c53a24a4
\ No newline at end of file
+5c35e26926a43abf3ddcf782b09d96ce82d447a7db9ee9994c0aa811e431f8c06c11ce022c2a6ccf8d5f79f1cdedee2e8c20ca6d1e7cc5129ebcfae9568b2f87
\ 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 c261a0edea..328d68b05f 100644
--- a/tests/test_mgxs_library_condense/inputs_true.dat
+++ b/tests/test_mgxs_library_condense/inputs_true.dat
@@ -1 +1 @@
-df2e5370925785e061e094561e9d2048c3104aaecf533ee9590a187d4597e53b489fb6e8cc54ed878f7d313bcf00586edceae4ff712c837faaa5ddab0ad378b3
\ No newline at end of file
+2b2a2f5778b03f87d20fa6da96cc19db0489f69d4d5f0cac02dd407fd8e53a082081bfef35c4310cb2e0651254766d499e89279e711fd6fd93f913c964855839
\ 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 2ca1810e97..67509bd510 100644
--- a/tests/test_mgxs_library_distribcell/inputs_true.dat
+++ b/tests/test_mgxs_library_distribcell/inputs_true.dat
@@ -1 +1 @@
-687358da3e7d658b6187e1d76280437d5b1a97a7ca3920483792e74de6fa9556fa86f4d55150c03d8628b3aa424afa187d8745f087f252ad0fca44ccc2a85f4c
\ No newline at end of file
+ad427594bd8a68ad35382bc34b5932e7c78480b6e327caf63782d563fd6e6e5fb4e7b0dfd9094394a5db092f789c473dbb08cb6b3d0c0296edcfc247dbe95d6f
\ 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 c261a0edea..328d68b05f 100644
--- a/tests/test_mgxs_library_hdf5/inputs_true.dat
+++ b/tests/test_mgxs_library_hdf5/inputs_true.dat
@@ -1 +1 @@
-df2e5370925785e061e094561e9d2048c3104aaecf533ee9590a187d4597e53b489fb6e8cc54ed878f7d313bcf00586edceae4ff712c837faaa5ddab0ad378b3
\ No newline at end of file
+2b2a2f5778b03f87d20fa6da96cc19db0489f69d4d5f0cac02dd407fd8e53a082081bfef35c4310cb2e0651254766d499e89279e711fd6fd93f913c964855839
\ 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 4cebb274ec..9e2bc06f18 100644
--- a/tests/test_mgxs_library_mesh/inputs_true.dat
+++ b/tests/test_mgxs_library_mesh/inputs_true.dat
@@ -1 +1 @@
-7f3aec9cedab76262de3706427ccba88b4c81fd4c9a033ff5467671ca21abe13b3981100d688502818bdd0534db22438970b02d652ca9d105557276de2d2a550
\ No newline at end of file
+68c7695d7ae0367c59155eab05d3fe859cae895170f2cd32d4463af340a9a2035be16221b1eda8e2a1132bfe1b8163ca8d964fb1b23274c232fb10fd88274aea
\ 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 c261a0edea..328d68b05f 100644
--- a/tests/test_mgxs_library_no_nuclides/inputs_true.dat
+++ b/tests/test_mgxs_library_no_nuclides/inputs_true.dat
@@ -1 +1 @@
-df2e5370925785e061e094561e9d2048c3104aaecf533ee9590a187d4597e53b489fb6e8cc54ed878f7d313bcf00586edceae4ff712c837faaa5ddab0ad378b3
\ No newline at end of file
+2b2a2f5778b03f87d20fa6da96cc19db0489f69d4d5f0cac02dd407fd8e53a082081bfef35c4310cb2e0651254766d499e89279e711fd6fd93f913c964855839
\ 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 f3c25d4d50..593111f329 100644
--- a/tests/test_mgxs_library_nuclides/inputs_true.dat
+++ b/tests/test_mgxs_library_nuclides/inputs_true.dat
@@ -1 +1 @@
-332fd9ff1ca576410ffc6c0f3f03c00618fc863509dc3725f2f3a82134e2400de9c1edf2adc68cb8bce528789094f8eb468371e65cbc13efe76d76467ef291d9
\ No newline at end of file
+63f6f8ae24e0d8e23731c903a59e3f5e0edff730933ef6f8836ebf78949db75542c5794a6486c27016ad22e4375b8a18092cd1d1e025162afd01936cac2f205b
\ No newline at end of file
diff --git a/tests/test_periodic/inputs_true.dat b/tests/test_periodic/inputs_true.dat
index 0b49ac2aea..ed1bc7d1b4 100644
--- a/tests/test_periodic/inputs_true.dat
+++ b/tests/test_periodic/inputs_true.dat
@@ -1 +1 @@
-f427510feb8a63ee2246613e65c9e9a488b6b7df11ce5f5ab0c61b23f299e150a27068ee110f77c64b5bb82882b6d0a428e06de681df2bd83facb9ebc46fb54c
\ No newline at end of file
+259ea7c22920ddea0bc076ee77d35e76f36d2c7043cb8d036b182a11fd7d0f6524e3cbd9c6b0bf4a1af905ebe10b765d3d43e43e899d3edbb601baf6fd172365
\ No newline at end of file
diff --git a/tests/test_tallies/inputs_true.dat b/tests/test_tallies/inputs_true.dat
index 196925c387..5f4bebb0d2 100644
--- a/tests/test_tallies/inputs_true.dat
+++ b/tests/test_tallies/inputs_true.dat
@@ -1 +1 @@
-11adb9111f20950e28b1c1929ee4ca0c9a6b2524de89bef44a495b2fe8cda3a2acac9e87d64ddb5eba591c8d22289956cb1f024d31e05da3c9a4162b8c589d85
\ No newline at end of file
+96d2f92c6017e62d688e3ca245c2ff7904a92816d188d096829440cd8fcfd4f8639dc67c12d54b324081c19e1c7dd2e79c1caeac53d7826399f11766826d5410
\ 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 fa61e20b78..6d2990754d 100644
--- a/tests/test_tally_aggregation/inputs_true.dat
+++ b/tests/test_tally_aggregation/inputs_true.dat
@@ -1 +1 @@
-bc17ba12ee5de7e6b0226e589be9044af725ff4e27683b765a9c75e5629176b5ca51d1e0306028ae90185d64644babf9ac22e4753f092b4b836790f4e162f9d0
\ No newline at end of file
+4a4e481b9af3612c71bdc93245011555807061bbd9d9be4c5b399f2c38820d38d9ce3ac6255d045415a216737eac65fb0f0b6e331e49b90bf8edc814d0f2f0e8
\ 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 56798828c6..b0da0ed247 100644
--- a/tests/test_tally_arithmetic/inputs_true.dat
+++ b/tests/test_tally_arithmetic/inputs_true.dat
@@ -1 +1 @@
-6b59ea3a0dc0d25c590f724b8c051a54e8d7836467ba31b7da72b0574398e6c73160a180524952ea983b0e7a7de776d2d7102d280d5a4e7e3624bd76f6f42a09
\ No newline at end of file
+6747131dad4c1efd8c87d857ce9127cb16ec883fdf5fabe309d82732d47851424273e9ad4878a335555d8b25bb0c0a15e68ac30e355ae346e9885c499e9ec979
\ No newline at end of file
diff --git a/tests/test_tally_slice_merge/inputs_true.dat b/tests/test_tally_slice_merge/inputs_true.dat
index a40c0a01df..7a747e6b52 100644
--- a/tests/test_tally_slice_merge/inputs_true.dat
+++ b/tests/test_tally_slice_merge/inputs_true.dat
@@ -1 +1 @@
-6d9ebab08ccce003e6128c6346ffd80e69a957fab15e9a0e211771efa68b24f276e62781f8471c72072f9017380d7e821c38002c03689993efed45db9590c039
\ No newline at end of file
+144dd4059444fad5e2e4fa20681fbdc74c0e5cbf3265104a0b49d87c768798eaeb25e3c6c795bcac2eebdde784c51588006d62c9f25be96dda5c51011a76b7c1
\ No newline at end of file
diff --git a/tests/test_triso/inputs_true.dat b/tests/test_triso/inputs_true.dat
index 4f58f14fbb..561877ad93 100644
--- a/tests/test_triso/inputs_true.dat
+++ b/tests/test_triso/inputs_true.dat
@@ -1 +1 @@
-033b09236ffceab5f0f7860d4926e0a66f328c6dd6fa48b28d6237278d42f9e06a28f2368f273773e417b8177705bc9a5e3ef67335734e5f17ff9843b72a2357
\ No newline at end of file
+b22973093e2b0690b30fb1262a11e27004555b796c446d256cb58a1d7329888ab60c1b93729b3d74bb015b98aa434416daa2dc2aee526eb8df0e9052911f94b4
\ No newline at end of file
diff --git a/tests/test_triso/test_triso.py b/tests/test_triso/test_triso.py
index 386be00b36..685034491f 100644
--- a/tests/test_triso/test_triso.py
+++ b/tests/test_triso/test_triso.py
@@ -93,7 +93,6 @@ class TRISOTestHarness(PyAPITestHarness):
         settings.export_to_xml()
 
         mats = openmc.Materials([fuel, porous_carbon, ipyc, sic, opyc, graphite])
-        mats.default_temperature = '294K'
         mats.export_to_xml()
 
 
diff --git a/tests/test_volume_calc/inputs_true.dat b/tests/test_volume_calc/inputs_true.dat
index 3a2d9c4747..ddfd497de4 100644
--- a/tests/test_volume_calc/inputs_true.dat
+++ b/tests/test_volume_calc/inputs_true.dat
@@ -1 +1 @@
-8dc4641e35f7770b8297eab9f71080c62a1c9607f36f7671cc61d47e0714887dea2f4c2ee515b23f39c38b1ea256c695d7c4d0ad95f5d7497a52d15f2ead33a5
\ No newline at end of file
+382404d3061d2c847c87654ab12594ba3fbb7e3a82327da872b5fe2029018ef4d5d3376fceba5c2229ea6f85e1fb63650caf54baed3f3b0304137fde61a98d63
\ No newline at end of file
diff --git a/tests/test_volume_calc/test_volume_calc.py b/tests/test_volume_calc/test_volume_calc.py
index 656f4654a0..fa267efb6a 100644
--- a/tests/test_volume_calc/test_volume_calc.py
+++ b/tests/test_volume_calc/test_volume_calc.py
@@ -24,7 +24,6 @@ class VolumeTest(PyAPITestHarness):
         fuel.set_density('g/cc', 4.5)
 
         materials = openmc.Materials((water, fuel))
-        materials.default_temperature = '294K'
         materials.export_to_xml()
 
         cyl = openmc.ZCylinder(1, R=1.0, boundary_type='vacuum')