diff --git a/mc-performance/mcnp/input b/mc-performance/mcnp/input
index 90f3bf6..5592ad7 100644
--- a/mc-performance/mcnp/input
+++ b/mc-performance/mcnp/input
@@ -61,7 +61,7 @@ c
 6      11  -3.044      -5 36 -37   imp:n=1    $ top FA region
 7      10  -1.746      -5 37 -38   imp:n=1    $ top nozzle region
 8      7   -4.28       -7 38 -39   imp:n=1    $ upper plate region
-9      4   0.06614   6 -7 32 -38   imp:n=1    $ downcomer
+9      3   0.07416   6 -7 32 -38   imp:n=1    $ downcomer
 10     5   -7.9      7 -8 31 -39   imp:n=1    $ reactor pressure vessel
 11     6   -4.32     5 -6 32 -34   imp:n=1    $ bottom of radial reflector
 12     7   -4.28     5 -6 36 -38   imp:n=1    $ top of radial reflector
diff --git a/mc-performance/openmc/geometry.xml b/mc-performance/openmc/geometry.xml
index 2407bf7..064143a 100644
--- a/mc-performance/openmc/geometry.xml
+++ b/mc-performance/openmc/geometry.xml
@@ -29,7 +29,7 @@
   <cell id="6"  material="11" surfaces="  -5 36 -37" /> <!-- Top FA region -->
   <cell id="7"  material="10" surfaces="  -5 37 -38" /> <!-- Top nozzle region -->
   <cell id="8"  material="7"  surfaces="  -7 38 -39" /> <!-- Upper plate region -->
-  <cell id="9"  material="4"  surfaces="6 -7 32 -38" /> <!-- Downcomer -->
+  <cell id="9"  material="3"  surfaces="6 -7 32 -38" /> <!-- Downcomer -->
   <cell id="10" material="5"  surfaces="7 -8 31 -39" /> <!-- RPV -->
   <cell id="11" material="6"  surfaces="5 -6 32 -34" /> <!-- Bottom of radial reflector -->
   <cell id="12" material="7"  surfaces="5 -6 36 -38" /> <!-- Top of radial reflector -->