adding get_all_nuclides method to geometry class (#2796)

Co-authored-by: Paul Romano <[email protected]>

openmc/geometry.py

@@ -391,6 +391,20 @@ def get_all_universes(self) -> typing.Dict[int, openmc.Universe]:
         universes.update(self.root_universe.get_all_universes())
         return universes
 
+    def get_all_nuclides(self) -> typing.List[str]:
+        """Return all nuclides within the geometry.
+
+        Returns
+        -------
+        list
+            Sorted list of all nuclides in materials appearing in the geometry
+
+        """
+        all_nuclides = set()
+        for material in self.get_all_materials().values():
+            all_nuclides |= set(material.get_nuclides())
+        return sorted(all_nuclides)
+
     def get_all_materials(self) -> typing.Dict[int, openmc.Material]:
         """Return all materials within the geometry.
 

tests/unit_tests/test_geometry.py

@@ -378,3 +378,15 @@ def get_cyl_cell(r1, r2, z1, z2, fill):
     # There should be 0 remaining redundant surfaces
     n_redundant_surfs = len(geom.remove_redundant_surfaces().keys())
     assert n_redundant_surfs == 0
+
+def test_get_all_nuclides():
+    m1 = openmc.Material()
+    m1.add_nuclide('Fe56', 1)
+    m1.add_nuclide('Be9', 1)
+    m2 = openmc.Material()
+    m2.add_nuclide('Be9', 1)
+    s = openmc.Sphere()
+    c1 = openmc.Cell(fill=m1, region=-s)
+    c2 = openmc.Cell(fill=m2, region=+s)
+    geom = openmc.Geometry([c1, c2])
+    assert geom.get_all_nuclides() == ['Be9', 'Fe56']