Option to divide material volumes by pin divisions

openmc/model/funcs.py

@@ -448,7 +448,8 @@ def subdivide(surfaces):
     return regions
 
 
-def pin(surfaces, materials, subdivisions=None, universe_id=None, name=""):
+def pin(surfaces, materials, subdivisions=None, divide_vols=True,
+        universe_id=None, name=""):
     """Convenience function for building a fuel pin
 
     Parameters
@@ -466,6 +467,11 @@ def pin(surfaces, materials, subdivisions=None, universe_id=None, name=""):
         Dictionary describing which rings to subdivide and how
         many times. Keys are indexes of the annular rings
         to be divided. Will construct equal area rings
+    divide_vols : bool
+        If this evaluates to ``True``, then volumes of subdivided
+        materials will also be divided by the number of divisions.
+        Otherwise the volume of the original material will not be
+        modified before subdivision
     universe_id : None or int
         Identifier for this universe
     name : str
@@ -555,6 +561,10 @@ def pin(surfaces, materials, subdivisions=None, universe_id=None, name=""):
 
             surfaces = (
                     surfaces[:ring_index] + new_surfs + surfaces[ring_index:])
+
+            if divide_vols and materials[ring_index].volume is not None:
+                materials[ring_index].volume /= nr
+
             materials = (
                     materials[:ring_index]
                     + [materials[ring_index].clone() for _i in range(nr - 1)]

tests/unit_tests/test_pin.py

@@ -23,7 +23,9 @@ def get_pin_radii(pin_univ):
 @pytest.fixture
 def pin_mats():
     fuel = openmc.Material(name="UO2")
+    fuel.volume = 100
     clad = openmc.Material(name="zirc")
+    clad.volume = 100
     water = openmc.Material(name="water")
     return fuel, clad, water
 
@@ -73,6 +75,11 @@ def test_subdivide(pin_mats, good_radii, surf_type):
     div0 = pin(surfs, pin_mats, {0: N})
     assert len(div0.cells) == len(pin_mats) + N - 1
 
+    # Check volume of fuel material
+    for mid, mat in div0.get_all_materials().items():
+        if mat.name == "UO2":
+            assert mat.volume == pytest.approx(100 / N)
+
     # check volumes of new rings
     radii = get_pin_radii(div0)
     bounds = [0] + radii[:N]
@@ -83,6 +90,11 @@ def test_subdivide(pin_mats, good_radii, surf_type):
     new_pin = pin(surfs, pin_mats, {1: N})
     assert len(new_pin.cells) == len(pin_mats) + N - 1
 
+    # Check volume of clad material
+    for mid, mat in div0.get_all_materials().items():
+        if mat.name == "zirc":
+            assert mat.volume == pytest.approx(100 / N)
+
     # check volumes of new rings
     radii = get_pin_radii(new_pin)
     sqrs = numpy.square(radii[:N + 1])