Add format spec for depletion chain XML file

docs/source/io_formats/depletion_chain.rst

@@ -0,0 +1,102 @@
+.. _io_chain:
+
+============================
+Depletion Chain -- chain.xml
+============================
+
+A depletion chain file has a ``<depletion_chain>`` root element with one or more
+``<nuclide>`` child elements. The decay, reaction, and fission product data for
+each nuclide appears as child elements of ``<nuclide>``.
+
+---------------------
+``<nuclide>`` Element
+---------------------
+
+The ``<nuclide>`` element contains information on the decay modes, reactions,
+and fission product yields for a given nuclide in the depletion chain. This
+element may have the following attributes:
+
+  :name:
+    Name of the nuclide
+
+  :half_life:
+    Half-life of the nuclide in [s]
+
+  :decay_modes:
+    Number of decay modes present
+
+  :decay_energy:
+    Decay energy released in [eV]
+
+  :reactions:
+    Number of reactions present
+
+For each decay mode, a :ref:`io_chain_decay` appears as a child of
+``<nuclide>``. For each reaction present, a :ref:`io_chain_reaction` appears as
+a child of ``<nuclide>``. If the nuclide is fissionable, a :ref:`io_chain_nfy`
+appears as well.
+
+.. _io_chain_decay:
+
+-------------------
+``<decay>`` Element
+-------------------
+
+The ``<decay>`` element represents a single decay mode and has the following
+attributes:
+
+  :type:
+    The type of the decay, e.g. 'ec/beta+'
+
+  :target:
+    The daughter nuclide produced from the decay
+
+  :branching_ratio:
+    The branching ratio for this decay mode
+
+.. _io_chain_reaction:
+
+----------------------
+``<reaction>`` Element
+----------------------
+
+The ``<reaction>`` element represents a single transmutation reaction. This
+element has the following attributes:
+
+  :type:
+    The type of the reaction, e.g., '(n,gamma)'
+
+  :Q:
+    The Q value of the reaction in [eV]
+
+  :target:
+    The nuclide produced in the reaction (absent if the type is 'fission')
+
+  :branching_ratio:
+    The branching ratio for the reaction
+
+.. _io_chain_nfy:
+
+------------------------------------
+``<neutron_fission_yields>`` Element
+------------------------------------
+
+The ``<neutron_fission_yields>`` element provides yields of fission products for
+fissionable nuclides. It has the follow sub-elements:
+
+  :energies:
+    Energies in [eV] at which yields for products are tabulated
+
+  :fission_yields:
+
+    Fission product yields for a single energy point. This element itself has a
+    number of attributes/sub-elements:
+
+      :energy:
+        Energy in [eV] at which yields are tabulated
+
+      :products:
+        Names of fission products
+
+      :data:
+        Independent yields for each fission product

docs/source/io_formats/index.rst

@@ -30,6 +30,7 @@ Data Files
    :maxdepth: 2
 
    cross_sections
+   depletion_chain
    nuclear_data
    mgxs_library
    data_wmp