diff --git a/docs/source/io_formats/depletion_results.rst b/docs/source/io_formats/depletion_results.rst
index fcbc4fb99..d35e25146 100644
--- a/docs/source/io_formats/depletion_results.rst
+++ b/docs/source/io_formats/depletion_results.rst
@@ -12,23 +12,23 @@ The current version of the depletion results file format is 1.0.
              - **version** (*int[2]*) -- Major and minor version of the
                statepoint file format.
 
-:Datasets: - **eigenvalues** (*float[][]*) -- k-eigenvalues at each
+:Datasets: - **eigenvalues** (*double[][]*) -- k-eigenvalues at each
              time/stage. This array has shape (number of timesteps, number of
              stages).
-           - **number** (*float[][][][]*) -- Total number of atoms. This array
+           - **number** (*double[][][][]*) -- Total number of atoms. This array
              has shape (number of timesteps, number of stages, number of
              materials, number of nuclides).
-           - **reaction rates** (*float[][][][][]*) -- Reaction rates used to
+           - **reaction rates** (*double[][][][][]*) -- Reaction rates used to
              build depletion matrices. This array has shape (number of
              timesteps, number of stages, number of materials, number of
              nuclides, number of reactions).
-           - **time** (*float[][2]*) -- Time in [s] at beginning/end of each
+           - **time** (*double[][2]*) -- Time in [s] at beginning/end of each
              step.
 
 **/materials/<id>/**
 
 :Attributes: - **index** (*int*) -- Index used in results for this material
-             - **volume** (*float*) -- Volume of this material in [cm^3]
+             - **volume** (*double*) -- Volume of this material in [cm^3]
 
 **/nuclides/<name>/**
 
diff --git a/docs/source/pythonapi/deplete.rst b/docs/source/pythonapi/deplete.rst
index 61c5dd18c..d4055f0fd 100644
--- a/docs/source/pythonapi/deplete.rst
+++ b/docs/source/pythonapi/deplete.rst
@@ -27,6 +27,17 @@ specific to OpenMC is available using the following class:
 
    Operator
 
+When running in parallel using `mpi4py <http://mpi4py.scipy.org>`_, the MPI
+intercommunicator used can be changed by modifying the following module
+variable. If it is not explicitly modified, it defaults to
+``mpi4py.MPI.COMM_WORLD``.
+
+.. data:: comm
+
+   MPI intercommunicator used to call OpenMC library
+
+   :type: mpi4py.MPI.Comm
+
 Internal Classes and Functions
 ------------------------------
 
diff --git a/openmc/data/data.py b/openmc/data/data.py
index 70bc00bd9..d0bb65648 100644
--- a/openmc/data/data.py
+++ b/openmc/data/data.py
@@ -327,8 +327,12 @@ def zam(name):
         Atomic number, mass number, and metastable state
 
     """
-    symbol, A, state = re.match(r'([A-Zn][a-z]*)(\d+)((?:_[em]\d+)?)',
-                                name).groups()
+    try:
+        symbol, A, state = re.match(r'([A-Zn][a-z]*)(\d+)((?:_[em]\d+)?)',
+                                    name).groups()
+    except AttributeError:
+        raise ValueError("'{}' does not appear to be a nuclide name in GND "
+                         "format.".format(name))
     metastable = int(state[2:]) if state else 0
     return (ATOMIC_NUMBER[symbol], int(A), metastable)
 
diff --git a/openmc/deplete/atom_number.py b/openmc/deplete/atom_number.py
index 9a32dfa3a..b5357280c 100644
--- a/openmc/deplete/atom_number.py
+++ b/openmc/deplete/atom_number.py
@@ -41,7 +41,7 @@ class AtomNumber(object):
     n_nuc_burn : int
         Number of burnable nuclides.
     n_nuc : int
-        Number of nuclidess.
+        Number of nuclides.
 
     """
     def __init__(self, local_mats, nuclides, volume, n_nuc_burn):
diff --git a/openmc/deplete/chain.py b/openmc/deplete/chain.py
index 612ec29cb..fbe679222 100644
--- a/openmc/deplete/chain.py
+++ b/openmc/deplete/chain.py
@@ -55,15 +55,12 @@ def replace_missing(product, decay_data):
         Replacement for missing product in GND format.
 
     """
-
-    symbol, A, state = re.match(r'([A-Zn][a-z]*)(\d+)((?:_m\d+)?)',
-                                product).groups()
-    Z = openmc.data.ATOMIC_NUMBER[symbol]
-    A = int(A)
+    # Determine atomic number, mass number, and metastable state
+    Z, A, state = openmc.data.zam(product)
+    symbol = openmc.data.ATOMIC_SYMBOL[Z]
 
     # First check if ground state is available
     if state:
-        metastable_state = int(state[2:])
         product = '{}{}'.format(symbol, A)
 
     # Find isotope with longest half-life
diff --git a/tests/unit_tests/test_data_misc.py b/tests/unit_tests/test_data_misc.py
index 7d00b7bc7..616744926 100644
--- a/tests/unit_tests/test_data_misc.py
+++ b/tests/unit_tests/test_data_misc.py
@@ -66,3 +66,5 @@ def test_zam():
     assert openmc.data.zam('Am242') == (95, 242, 0)
     assert openmc.data.zam('Am242_m1') == (95, 242, 1)
     assert openmc.data.zam('Am242_m10') == (95, 242, 10)
+    with pytest.raises(ValueError):
+        openmc.data.zam('garbage')