add to existing temp interp test, update doccs

docs/source/io_formats/settings.rst

@@ -875,10 +875,10 @@ cell temperature is 340 K and the tolerance is 15 K, then the closest
 temperature in the range of 325 K to 355 K will be used to evaluate cross
 sections. If the ``<temperature_method>`` is "interpolation", the tolerance
 specified applies to cell temperatures outside of the data bounds. For example,
-If a cell is specified at 695K, a tolerance of 15K and data only available at
-700K and 1000K, the cell's cross sections will be evaluated at 700K, since
-desired temperature of 695K is within the tolerance of the actual data despite
-not being bounded on both sides.
+if a cell is specified at 695K, a tolerance of 15K and data is only available
+at 700K and 1000K, the cell's cross sections will be evaluated at 700K, since
+the desired temperature of 695K is within the tolerance of the actual data
+despite not being bounded on both sides.
 
   *Default*: 10 K
 

tests/unit_tests/test_temp_interp.py

@@ -86,6 +86,70 @@ def cross_section(value):
     lib.export_to_xml('cross_sections_fake.xml')
 
 
+def fake_thermal_scattering():
+    """Create a fake thermal scattering library for U-235 at 294K and 600K
+    """
+    fake_tsl = openmc.data.ThermalScattering("c_U_fake", 1.9968, 4.9, [0.0253])
+    fake_tsl.nuclides = ['U235']
+
+    # Create elastic reaction
+    bragg_edges = [0.00370672, 0.00494229]
+    factors = [0.00375735, 0.01386287]
+    coherent_xs = openmc.data.CoherentElastic(bragg_edges, factors)
+    incoherent_xs_294 = openmc.data.Tabulated1D([0.00370672, 0.00370672], [0.00370672, 0.00370672])
+    elastic_xs_base = openmc.data.Sum((coherent_xs, incoherent_xs_294))
+    elastic_xs = {'294K': elastic_xs_base, '600K': elastic_xs_base}
+    coherent_dist = openmc.data.CoherentElasticAE(coherent_xs)
+    incoherent_dist_294 = openmc.data.IncoherentElasticAEDiscrete([
+        [-0.6, -0.18, 0.18, 0.6], [-0.6, -0.18, 0.18, 0.6]
+    ])
+    incoherent_dist_600 = openmc.data.IncoherentElasticAEDiscrete([
+        [-0.1, -0.2, 0.2, 0.1], [-0.1, -0.2, 0.2, 0.1]
+    ])
+    elastic_dist = {
+        '294K': openmc.data.MixedElasticAE(coherent_dist, incoherent_dist_294),
+        '600K': openmc.data.MixedElasticAE(coherent_dist, incoherent_dist_600)
+        }
+    fake_tsl.elastic = openmc.data.ThermalScatteringReaction(elastic_xs, elastic_dist)
+
+    # Create inelastic reaction
+    inelastic_xs = {
+        '294K': openmc.data.Tabulated1D([1.0e-5, 4.9], [13.4, 3.35]),
+        '600K': openmc.data.Tabulated1D([1.0e-2, 10], [1.4, 5])
+        }
+    breakpoints = [3]
+    interpolation = [2]
+    energy = [1.0e-5, 4.3e-2, 4.9]
+    energy_out = [
+        openmc.data.Tabular([0.0002, 0.067, 0.146, 0.366], [0.25, 0.25, 0.25, 0.25]),
+        openmc.data.Tabular([0.0001, 0.009, 0.137, 0.277], [0.25, 0.25, 0.25, 0.25]),
+        openmc.data.Tabular([0.0579, 4.555, 4.803, 4.874], [0.25, 0.25, 0.25, 0.25]),
+    ]
+    for eout in energy_out:
+        eout.normalize()
+        eout.c = eout.cdf()
+    discrete = openmc.stats.Discrete([-0.9, -0.6, -0.3, -0.1, 0.1, 0.3, 0.6, 0.9], [1/8]*8)
+    discrete.c = discrete.cdf()[1:]
+    mu = [[discrete]*4]*3
+    dist = openmc.data.IncoherentInelasticAE(
+        breakpoints, interpolation, energy, energy_out, mu)
+    inelastic_dist = {'294K': dist, '600K': dist}
+    inelastic = openmc.data.ThermalScatteringReaction(inelastic_xs, inelastic_dist)
+    fake_tsl.inelastic = inelastic
+
+    return fake_tsl
+
+
+def edit_fake_cross_sections():
+    """Edit the test cross sections xml to include fake thermal scattering data
+    """
+    lib = openmc.data.DataLibrary.from_xml("cross_sections_fake.xml")
+    c_U_fake = fake_thermal_scattering()
+    c_U_fake.export_to_hdf5("c_U_fake.h5")
+    lib.register_file("c_U_fake.h5")
+    lib.export_to_xml("cross_sections_fake.xml")
+
+
 @pytest.fixture(scope='module')
 def model(tmp_path_factory):
     tmp_path = tmp_path_factory.mktemp("temp_interp")
@@ -119,21 +183,23 @@ def model(tmp_path_factory):
 
 
 @pytest.mark.parametrize(
-    ["method", "temperature", "fission_expected"],
+    ["method", "temperature", "fission_expected", "tolerance"],
     [
-        ("nearest", 300.0, 0.5),
-        ("nearest", 600.0, 1.0),
-        ("nearest", 900.0, 0.5),
-        ("interpolation", 360.0, 0.6),
-        ("interpolation", 450.0, 0.75),
-        ("interpolation", 540.0, 0.9),
-        ("interpolation", 660.0, 0.9),
-        ("interpolation", 750.0, 0.75),
-        ("interpolation", 840.0, 0.6),
+        ("nearest", 300.0, 0.5, 10),
+        ("nearest", 600.0, 1.0, 10),
+        ("nearest", 900.0, 0.5, 10),
+        ("interpolation", 360.0, 0.6, 10),
+        ("interpolation", 450.0, 0.75, 10),
+        ("interpolation", 540.0, 0.9, 10),
+        ("interpolation", 660.0, 0.9, 10),
+        ("interpolation", 750.0, 0.75, 10),
+        ("interpolation", 840.0, 0.6, 10),
+        ("interpolation", 295.0, 0.5, 10),
+        ("interpolation", 990.0, 0.5, 100),
     ]
 )
-def test_interpolation(model, method, temperature, fission_expected):
-    model.settings.temperature = {'method': method, 'default': temperature}
+def test_interpolation(model, method, temperature, fission_expected, tolerance):
+    model.settings.temperature = {'method': method, 'default': temperature, "tolerance": tolerance}
     sp_filename = model.run()
     with openmc.StatePoint(sp_filename) as sp:
         t = sp.tallies[model.tallies[0].id]
@@ -152,3 +218,34 @@ def test_interpolation(model, method, temperature, fission_expected):
             assert k.n == pytest.approx(nu*fission_expected)
         else:
             assert abs(k.n - nu*fission_expected) <= 3*k.s
+
+
+def test_temperature_interpolation_tolerance(model):
+    """Test applying global and cell temperatures with thermal scattering libraries
+    """
+    edit_fake_cross_sections()
+    model.materials[0].add_s_alpha_beta("c_U_fake")
+
+    # Default k-effective, using the thermal scattering data's minimum available temperature
+    model.settings.temperature = {'method': "nearest", 'default': 294, "tolerance": 50}
+    sp_filename = model.run()
+    with openmc.StatePoint(sp_filename) as sp:
+        default_k = sp.keff.n
+
+    # Get k-effective with temperature below the minimum but in interpolation mode
+    model.settings.temperature = {'method': "interpolation", 'default': 255, "tolerance": 50}
+    sp_filename = model.run()
+    with openmc.StatePoint(sp_filename) as sp:
+        interpolated_k = sp.keff.n
+
+    # Get the k-effective with the temperature applied to the cell, instead of globally
+    model.settings.temperature = {'method': "interpolation", 'default': 500, "tolerance": 50}
+    for cell in model.geometry.get_all_cells().values():
+        cell.temperature = 275
+    sp_filename = model.run()
+    with openmc.StatePoint(sp_filename) as sp:
+        cell_k = sp.keff.n
+
+    # All calculated k-effectives should be equal
+    assert default_k == pytest.approx(interpolated_k)
+    assert interpolated_k == pytest.approx(cell_k)