Ensure # fission yields == # burnable materials in cram.deplete

If the fission yields are a single entry, then
itertools.repeat is used to apply the fission yields to all
burnable materials. Otherwise, check that the number of
fission yield libraries is equal to the number of materials
to be burned.

openmc/deplete/cram.py

@@ -42,10 +42,14 @@ def deplete(chain, x, rates, dt, matrix_func=None):
         Updated atom number vectors for each material
     """
 
-    if not hasattr(chain, "fission_yields"):
-        fission_yields = repeat(chain.get_thermal_fission_yields())
-    else:
-        fission_yields = chain.fission_yields
+    fission_yields = chain.fission_yields
+    if len(fission_yields) == 1:
+        fission_yields = repeat(fission_yields[0])
+    elif len(fission_yields) != len(x):
+        raise ValueError(
+            "Number of material fission yield distributions {} is not equal "
+            "to the number of compositions {}".format(len(fission_yields),
+                len(x)))
 
     # Use multiprocessing pool to distribute work
     with Pool() as pool:

openmc/deplete/nuclide.py

@@ -86,9 +86,9 @@ class Nuclide(object):
     reactions : list of openmc.deplete.ReactionTuple
         Reaction information. Each element of the list is a named tuple with
         attribute 'type', 'target', 'Q', and 'branching_ratio'.
-    yield_data : dict of float to list
-        Maps tabulated energy to list of (product, yield) for all
-        neutron-induced fission products.
+    yield_data : dict of float to :class:`openmc.deplete.FissionYieldDistribution`
+        Fission product yields at tabulated energies for this nuclide. Can be
+        treated as a nested dictionary ``{energy: {product: yield}}``
     yield_energies : list of float
         Energies at which fission product yields exist
 
@@ -300,15 +300,15 @@ class FissionYieldDistribution(Mapping):
         -------
         FissionYieldDistribution
         """
-        yields = {}
+        all_yields = {}
         for elem_index, yield_elem in enumerate(element.iter("fission_yields")):
             energy = float(yield_elem.get("energy"))
             products = yield_elem.find("products").text.split()
-            yield_mapobj = map(float, yield_elem.find("data").text.split())
+            yields = map(float, yield_elem.find("data").text.split())
             # Get a map of products to their corresponding yield
-            yields[energy] = dict(zip(products, yield_mapobj))
+            all_yields[energy] = dict(zip(products, yields))
 
-        return cls.from_dict(yields)
+        return cls.from_dict(all_yields)
 
     @classmethod
     def from_dict(cls, fission_yields):
@@ -327,9 +327,7 @@ class FissionYieldDistribution(Mapping):
         energies = sorted(fission_yields)
 
         # Get a consistent set of products to produce a matrix of yields
-        shared_prod = set()
-        for prod_set in map(set, fission_yields.values()):
-            shared_prod |= prod_set
+        shared_prod = set.union(*(set(x) for x in fission_yields.values()))
         ordered_prod = sorted(shared_prod)
 
         yield_matrix = empty((len(energies), len(shared_prod)))
@@ -422,6 +420,9 @@ class FissionYield(Mapping):
     def __iter__(self):
         return iter(self.products)
 
+    def items(self):
+        return zip(self.products, self.yields)
+
     def __add__(self, other):
         new = self.copy()
         new += other

tests/unit_tests/test_deplete_chain.py

@@ -7,7 +7,7 @@ from itertools import product
 
 import numpy as np
 from openmc.data import zam, ATOMIC_SYMBOL
-from openmc.deplete import comm, Chain, reaction_rates, nuclide
+from openmc.deplete import comm, Chain, reaction_rates, nuclide, cram
 import pytest
 
 from tests import cdtemp
@@ -359,3 +359,10 @@ def test_fission_yield_attribute(simple_chain):
     empty_chain.fission_yields = [thermal_yields] * 2
     assert empty_chain.fission_yields[0] == thermal_yields
     assert empty_chain.fission_yields[1] == thermal_yields
+
+    # test failure with deplete function
+    # number fission yields != number of materials
+    dummy_conc = [[1, 2]] * (len(empty_chain.fission_yields) + 1)
+    with pytest.raises(
+            ValueError, match="fission yield.*not equal.*compositions"):
+       cram.deplete(empty_chain, dummy_conc, None, 0.5)