add continue feature for depletion

openmc/deplete/abc.py

@@ -556,7 +556,8 @@ def __init__(
             power_density: Optional[Union[float, Sequence[float]]] = None,
             source_rates: Optional[Sequence[float]] = None,
             timestep_units: str = 's',
-            solver: str = "cram48"
+            solver: str = "cram48",
+            continue_timesteps: bool = False,
         ):
         # Check number of stages previously used
         if operator.prev_res is not None:
@@ -629,6 +630,24 @@ def __init__(
             else:
                 raise ValueError(f"Invalid timestep unit '{unit}'")
 
+            # validate existing depletion steps are consistent with those passed to operator
+            if continue_timesteps:
+                completed_timesteps = operator.prev_res.get_times()
+                completed_source_rates = operator.prev_res.get_source_rates()
+                num_previous_steps_run = len(completed_timesteps)
+                if (
+                    np.equal(completed_timesteps, timesteps[: num_previous_steps_run]) and
+                    np.equal(completed_source_rates, source_rates[: num_previous_steps_run])
+                ):
+                    seconds = seconds[num_previous_steps_run:]
+                    source_rates = source_rates[num_previous_steps_run:]
+                else:
+                    raise ValueError(
+                        "You are attempting to continue a run in which the previous results "
+                        "do not have the same initial steps as those provided to the "
+                        "Integrator. Please make sure you are using the correct timesteps,"
+                        "powers or power densities, and previous results file."
+                    )
         self.timesteps = np.asarray(seconds)
         self.source_rates = np.asarray(source_rates)
 

tests/unit_tests/test_deplete_continue.py

@@ -0,0 +1,53 @@
+"""Unit tests for openmc.deplete continue run capability.
+
+These tests run in two steps: first a normal run and then a continue run based on the prev_results
+"""
+
+import pytest
+
+import openmc.deplete
+
+from tests import dummy_operator
+
+# test that the continue timesteps works when the second integrate call contains all previous timesteps
+@pytest.mark.parametrize("scheme", dummy_operator.SCHEMES)
+def test_continue(run_in_tmpdir, scheme):
+    # set up the problem
+
+    bundle = dummy_operator.SCHEMES[scheme]
+
+    operator = dummy_operator.DummyOperator()
+
+    # take first step
+    bundle.solver(operator, [0.75], 1.0).integrate()
+
+    # restart
+    prev_res = openmc.deplete.Results(
+        operator.output_dir / "depletion_results.h5")
+    operator = dummy_operator.DummyOperator(prev_res)
+
+    # if continue run happens, test passes
+    bundle.solver(operator, [0.75, 0.75], [1.0, 1.0], continue_timesteps = True).integrate()
+
+@pytest.mark.parametrize("scheme", dummy_operator.SCHEMES)
+def test_mismatched_initial_steps(run_in_tmpdir, scheme):
+    """Test to ensure that a continue run with different initial steps is properly caught"""
+
+    # set up the problem
+
+    bundle = dummy_operator.SCHEMES[scheme]
+
+    operator = dummy_operator.DummyOperator()
+
+    # take first step
+    bundle.solver(operator, [0.75, 0.75], [1.0,1.0]).integrate()
+
+    # restart
+    prev_res = openmc.deplete.Results(
+        operator.output_dir / "depletion_results.h5")
+    operator = dummy_operator.DummyOperator(prev_res)
+
+    # continue run with different previous step should cause a ValueError
+    # note the first step matches but the second does not while the third is a new step
+    with pytest.raises(ValueError):
+        bundle.solver(operator, [0.75, 0.5, 0.75], [1.0, 2.0, 1.0], continue_timesteps = True).integrate()