Allowing material making from class constructor (#3649)

Co-authored-by: Jon Shimwell <jon@proximafusion.com>
Co-authored-by: Paul Romano <paul.k.romano@gmail.com>

openmc/material.py

@@ -60,6 +60,26 @@ class Material(IDManagerMixin):
     temperature : float, optional
         Temperature of the material in Kelvin. If not specified, the material
         inherits the default temperature applied to the model.
+    density : float, optional
+        Density of the material (units defined separately)
+    density_units : str
+        Units used for `density`. Can be one of 'g/cm3', 'g/cc', 'kg/m3',
+        'atom/b-cm', 'atom/cm3', 'sum', or 'macro'.  The 'macro' unit only
+        applies in the case of a multi-group calculation. Defaults to 'sum'.
+    depletable : bool, optional
+        Indicate whether the material is depletable. Defaults to False.
+    volume : float, optional
+        Volume of the material in cm^3. This can either be set manually or
+        calculated in a stochastic volume calculation and added via the
+        :meth:`Material.add_volume_information` method.
+    components : dict of str to float or dict
+        Dictionary mapping element or nuclide names to their atom or weight
+        percent. To specify enrichment of an element, the entry of
+        ``components`` for that element must instead be a dictionary containing
+        the keyword arguments as well as a value for ``'percent'``
+    percent_type : {'ao', 'wo'}
+        Whether the values in `components` should be interpreted as atom percent
+        ('ao') or weight percent ('wo').
 
     Attributes
     ----------
@@ -111,17 +131,28 @@ class Material(IDManagerMixin):
     next_id = 1
     used_ids = set()
 
-    def __init__(self, material_id=None, name='', temperature=None):
+    def __init__(
+        self,
+        material_id: int | None = None,
+        name: str = "",
+        temperature: float | None = None,
+        density: float | None = None,
+        density_units: str = "sum",
+        depletable: bool | None = False,
+        volume: float | None = None,
+        components: dict | None = None,
+        percent_type: str = "ao",
+    ):
         # Initialize class attributes
         self.id = material_id
         self.name = name
         self.temperature = temperature
         self._density = None
-        self._density_units = 'sum'
-        self._depletable = False
+        self._density_units = density_units
+        self._depletable = depletable
         self._paths = None
         self._num_instances = None
-        self._volume = None
+        self._volume = volume
         self._atoms = {}
         self._isotropic = []
         self._ncrystal_cfg = None
@@ -136,6 +167,15 @@ class Material(IDManagerMixin):
         # If specified, a list of table names
         self._sab = []
 
+        # Set density if provided
+        if density is not None:
+            self.set_density(density_units, density)
+
+        # Add components if provided
+        if components is not None:
+            self.add_components(components, percent_type=percent_type)
+
+
     def __repr__(self) -> str:
         string = 'Material\n'
         string += '{: <16}=\t{}\n'.format('\tID', self._id)

tests/unit_tests/test_material.py

@@ -768,3 +768,54 @@ def test_mean_free_path():
     mat2.add_nuclide('Pb208', 1.0)
     mat2.set_density('g/cm3', 11.34)
     assert mat2.mean_free_path(energy=14e6) == pytest.approx(5.65, abs=1e-2)
+
+
+def test_material_from_constructor():
+    # Test that components and percent_type work in the constructor
+    components = {
+        'Li': {'percent': 0.5, 'enrichment': 60.0, 'enrichment_target': 'Li7'},
+        'O16': 1.0,
+        'Be': 0.5
+    }
+    mat = openmc.Material(
+        material_id=123,
+        name="test-mat",
+        components=components,
+        percent_type="ao"
+    )
+    # Check that nuclides were added
+    nuclide_names = [nuc.name for nuc in mat.nuclides]
+    assert 'O16' in nuclide_names
+    assert 'Be9' in nuclide_names
+    assert 'Li7' in nuclide_names
+    assert 'Li6' in nuclide_names
+    assert mat.id == 123
+    assert mat.name == "test-mat"
+
+    mat1 = openmc.Material(
+        **{
+            "material_id": 1,
+            "name": "neutron_star",
+            "density": 1e17,
+            "density_units": "kg/m3",
+        }
+    )
+    assert mat1.id == 1
+    assert mat1.name == "neutron_star"
+    assert mat1._density == 1e17
+    assert mat1._density_units == "kg/m3"
+    assert mat1.nuclides == []
+
+    mat2 = openmc.Material(
+        material_id=42,
+        name="plasma",
+        temperature=None,
+        density=1e-7,
+        density_units="g/cm3",
+    )
+    assert mat2.id == 42
+    assert mat2.name == "plasma"
+    assert mat2.temperature is None
+    assert mat2.density == 1e-7
+    assert mat2.density_units == "g/cm3"
+    assert mat2.nuclides == []