Fixing DerivedShape.getArea() for cold=true

armi/reactor/components/__init__.py

@@ -158,7 +158,7 @@ def getComponentArea(self, cold=False):
         Parameters
         ----------
         cold : bool, optional
-            Ignored for this component
+            If True, compute the area with as-input dimensions, instead of thermally-expanded.
         """
         coldArea = self.p.area
         if cold:
@@ -173,6 +173,13 @@ def getBoundingCircleOuterDiameter(self, Tc=None, cold=False):
         This is the smallest it can possibly be. Since this is used to determine
         the outer component, it will never be allowed to be the outer one.
 
+        Parameters
+        ----------
+        Tc : float
+            Ignored for this component
+        cold : bool, optional
+            If True, compute the area with as-input dimensions, instead of thermally-expanded.
+
         Notes
         -----
         Tc is not used in this method for this particular component.
@@ -451,8 +458,17 @@ def getComponentArea(self, cold=False):
         Parameters
         ----------
         cold : bool, optional
-            Ignored for this component
+            If True, compute the area with as-input dimensions, instead of thermally-expanded.
         """
+        if cold:
+            # At cold temp, the DerivedShape has the area of the parent minus the other siblings
+            parentArea = self.parent.getArea()
+            # NOTE: the assumption is there is only one DerivedShape in each Component
+            siblings = sum(
+                [c.getArea(cold=True) for c in self.parent if type(c) != DerivedShape]
+            )
+            return parentArea - siblings
+
         if self.parent.derivedMustUpdate:
             self.computeVolume()
 

armi/reactor/tests/test_components.py

@@ -17,6 +17,7 @@
 import math
 import unittest
 
+from armi.materials import air, alloy200
 from armi.materials.material import Material
 from armi.reactor import components
 from armi.reactor import flags
@@ -44,7 +45,7 @@
     ComponentType,
 )
 from armi.reactor.components import materials
-from armi.materials import air, alloy200
+from armi.reactor.tests.test_reactors import loadTestReactor
 
 
 class TestComponentFactory(unittest.TestCase):
@@ -482,6 +483,31 @@ def test_computeVolume(self):
         self.assertAlmostEqual(c.computeVolume(), 1386.5232044586771)
 
 
+class TestDerivedShapeGetArea(unittest.TestCase):
+    def test_getAreaColdTrue(self):
+        """Prove that the DerivedShape.getArea() works at cold=True."""
+        # load one-block test reactor
+        _o, r = loadTestReactor(
+            inputFileName="smallestTestReactor/armiRunSmallest.yaml"
+        )
+        b = r.core[0][0]
+
+        # ensure there is a DerivedShape in this Block
+        shapes = set([type(c) for c in b])
+        self.assertIn(Circle, shapes)
+        self.assertIn(DerivedShape, shapes)
+        self.assertIn(Helix, shapes)
+        self.assertIn(Hexagon, shapes)
+
+        # prove that getArea works on the block level
+        self.assertAlmostEqual(b.getArea(cold=True), b.getArea(cold=False), delta=1e-10)
+
+        # prove that getArea preserves the sum of all the areas, even if there is a DerivedShape
+        totalAreaCold = sum([c.getArea(cold=True) for c in b])
+        totalAreaHot = sum([c.getArea(cold=False) for c in b])
+        self.assertAlmostEqual(totalAreaCold, totalAreaHot, delta=1e-10)
+
+
 class TestCircle(TestShapedComponent):
     """Test circle shaped component."""
 

doc/release/0.4.rst

@@ -18,12 +18,14 @@ API Changes
 
 Bug Fixes
 ---------
+#. Fixed ``DerivedShape.getArea`` for ``cold=True``. (`PR#1831 <https://github.com/terrapower/armi/pull/1831>`_)
 #. Fixed error parsing command line integers in ``ReportsEntryPoint``. (`PR#1824 <https://github.com/terrapower/armi/pull/1824>`_)
 #. TBD
 
 Quality Work
 ------------
 #. Removing code that causes a deprecation warning (converting ``axialUnitGrid`` to ``AxialGrid.fromNCells``) (`PR#1809 <https://github.com/terrapower/armi/pull/1809>`_)
+#. TBD
 
 Changes that Affect Requirements
 --------------------------------