Expose tight coupling to OperatorSnapshots

armi/operators/operator.py

@@ -378,17 +378,26 @@ def _timeNodeLoop(self, cycle, timeNode):
         """Run the portion of the main loop that happens each subcycle."""
         self.r.p.timeNode = timeNode
         self.interactAllEveryNode(cycle, timeNode)
-        # perform tight coupling if requested
+        self._performTightCoupling(cycle, timeNode)
+
+    def _performTightCoupling(self, cycle: int, timeNode: int, writeDB: bool = True):
+        """if requested, perform tight coupling and write out database
+
+        Notes
+        -----
+        writeDB is False for OperatorSnapshots as the DB gets written at EOL.
+        """
         if self.couplingIsActive():
             self._convergenceSummary = collections.defaultdict(list)
             for coupledIteration in range(self.cs["tightCouplingMaxNumIters"]):
                 self.r.core.p.coupledIteration = coupledIteration + 1
                 converged = self.interactAllCoupled(coupledIteration)
                 if converged:
                     break
-            # database has not yet been written, so we need to write it.
-            dbi = self.getInterface("database")
-            dbi.writeDBEveryNode(cycle, timeNode)
+            if writeDB:
+                # database has not yet been written, so we need to write it.
+                dbi = self.getInterface("database")
+                dbi.writeDBEveryNode(cycle, timeNode)
 
     def _interactAll(self, interactionName, activeInterfaces, *args):
         """

armi/operators/snapshots.py

@@ -76,6 +76,7 @@ def _mainOperate(self):
             self.interactAllEveryNode(
                 ssCycle, ssNode, excludedInterfaceNames=("database",)
             )
+            self._performTightCoupling(ssCycle, ssNode, writeDB=False)
 
             # database is excluded at last snapshot since it writes at EOL
             exclude = ("database",) if (ssCycle, ssNode) == lastTimeStep else ()

armi/operators/tests/test_operators.py

@@ -27,6 +27,8 @@
 from armi.physics.neutronics.globalFlux.globalFluxInterface import (
     GlobalFluxInterfaceUsingExecuters,
 )
+from armi.utils import directoryChangers
+from armi.bookkeeping.db.databaseInterface import DatabaseInterface
 
 
 class InterfaceA(Interface):
@@ -107,6 +109,25 @@ def test_couplingIsActive(self):
         self.o.cs["tightCoupling"] = True
         self.assertTrue(self.o.couplingIsActive())
 
+    def test_dbWriteForCoupling(self):
+        with directoryChangers.TemporaryDirectoryChanger():
+            self.o.cs["tightCoupling"] = True
+            self.dbWriteForCoupling(writeDB=True)
+            self.dbWriteForCoupling(writeDB=False)
+
+    def dbWriteForCoupling(self, writeDB: bool):
+        self.o.removeAllInterfaces()
+        dbi = DatabaseInterface(self.r, self.o.cs)
+        dbi.initDB(fName=self._testMethodName + ".h5")
+        self.o.addInterface(dbi)
+        self.o._performTightCoupling(0, 0, writeDB=writeDB)
+        h5Contents = list(dbi.database.getH5Group(dbi.r).items())
+        if writeDB:
+            self.assertTrue(h5Contents)
+        else:
+            self.assertFalse(h5Contents)
+        dbi.database.close()
+
     def test_computeTightCouplingConvergence(self):
         """ensure that tight coupling convergence can be computed and checked
 

doc/release/0.2.rst

@@ -27,6 +27,7 @@ What's new in ARMI
 #. Allow MCNP material card number to be defined after the card is written. (`PR#1086 <https://github.com/terrapower/armi/pull/1086>`_)
 #. Refine logic for Block.getNumPins() to only count components that are actually pins. (`PR#1098 <https://github.com/terrapower/armi/pull/1098>`_)
 #. Improve handling of peak/max parameters by the UniformMeshConverter parameter mapper. (`PR#1108 <https://github.com/terrapower/armi/pull/1108>`_)
+#. Bug fix to expose new tight coupling functionality to ``OperatorSnapshots``. (`PR#1113 https://github.com/terrapower/armi/pull/1113`_)
 
 Bug fixes
 ---------