Implement stochastic volume calculation on Fortran side

docs/source/io_formats/index.rst

@@ -30,3 +30,4 @@ Output Files
    particle_restart
    track
    voxel
+   volume

docs/source/io_formats/nuclear_data.rst

@@ -1,4 +1,4 @@
-.. _usersguide_nuclear_data:
+.. _io_nuclear_data:
 
 ========================
 Nuclear Data File Format

docs/source/io_formats/volume.rst

@@ -0,0 +1,22 @@
+.. _io_volume:
+
+==================
+Volume File Format
+==================
+
+**/**
+
+:Attributes: - **samples** (*int*) -- Number of samples
+             - **lower_left** (*double[3]*) -- Lower-left coordinates of
+               bounding box
+             - **upper_right** (*double[3]*) -- Upper-right coordinates of
+               bounding box
+
+**/cell_<id>/**
+
+:Datasets: - **volume** (*double[2]*) -- Calculated volume and its uncertainty
+             in cubic centimeters
+           - **nuclides** (*char[][]*) -- Names of nuclides identified in the
+             cell
+           - **atoms** (*double[][2]*) -- Total number of atoms of each nuclide
+             and its uncertainty

docs/source/usersguide/input.rst

@@ -836,6 +836,35 @@ displayed. This element takes the following attributes:
 
     *Default*: 5
 
+``<volume_calc>`` Element
+-------------------------
+
+The ``<volume_calc>`` element indicates that a stochastic volume calculation
+should be run at the beginning of the simulation. This element has the following
+sub-elements/attributes:
+
+  :cells:
+    The unique IDs of cells for which the volume should be estimated.
+
+    *Default*: None
+
+  :samples:
+    The number of samples used to estimate volumes.
+
+    *Default*: None
+
+  :lower_left:
+     The lower-left Cartesian coordinates of a bounding box that is used to
+     sample points within.
+
+     *Default*: None
+
+  :upper_right:
+     The upper-right Cartesian coordinates of a bounding box that is used to
+     sample points within.
+
+     *Default*: None
+
 --------------------------------------
 Geometry Specification -- geometry.xml
 --------------------------------------