From 2525c2a3f89e9a8fd49ca4212e12d263289b2570 Mon Sep 17 00:00:00 2001
From: tjlaboss <travis@ktc-technology.com>
Date: Wed, 29 Mar 2017 20:05:26 -0400
Subject: [PATCH] Accounted for surfaces from a Complement().

---
 openmc/region.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/openmc/region.py b/openmc/region.py
index 012faca75f..ed1b727454 100644
--- a/openmc/region.py
+++ b/openmc/region.py
@@ -450,3 +450,23 @@ class Complement(Region):
         else:
             temp_region = ~self.node
         return temp_region.bounding_box
+
+    def get_surfaces_from_region(self, surfaces = OrderedDict()):
+        """
+        Recursively find all the surfaces referenced by the complement's node and return them
+        Overwrites method Region.get_surfaces_from_region()
+
+        Parameters
+        ----------
+        surfaces: collections.OrderedDict, optional
+            Dictionary mapping surface IDs to :class:`openmc.Surface` instances
+
+        Returns
+        -------
+        surfaces: collections.OrderedDict
+            Dictionary mapping surface IDs to :class:`openmc.Surface` instances
+
+        """
+        for region in self.node:
+            surfaces = region.get_surfaces_from_region(surfaces)
+        return surfaces