diff --git a/TestCases/radiation/p1adjoint/of_grad_cd.csv.ref b/TestCases/radiation/p1adjoint/of_grad_cd.csv.ref
new file mode 100644
index 000000000000..8c422aae7195
--- /dev/null
+++ b/TestCases/radiation/p1adjoint/of_grad_cd.csv.ref
@@ -0,0 +1,51 @@
+"VARIABLE"      , "GRADIENT"      , "FINDIFF_STEP"  
+0               , -0.000954218    , 0.001           
+1               , -0.00432384     , 0.001           
+2               , -0.0111485      , 0.001           
+3               , -0.0214656      , 0.001           
+4               , -0.0344212      , 0.001           
+5               , -0.0490221      , 0.001           
+6               , -0.0643278      , 0.001           
+7               , -0.0792041      , 0.001           
+8               , -0.0924318      , 0.001           
+9               , -0.103025       , 0.001           
+10              , -0.110239       , 0.001           
+11              , -0.113383       , 0.001           
+12              , -0.111898       , 0.001           
+13              , -0.105745       , 0.001           
+14              , -0.0956773      , 0.001           
+15              , -0.0830288      , 0.001           
+16              , -0.069201       , 0.001           
+17              , -0.0553022      , 0.001           
+18              , -0.0421316      , 0.001           
+19              , -0.0303252      , 0.001           
+20              , -0.0203976      , 0.001           
+21              , -0.0126387      , 0.001           
+22              , -0.00701749     , 0.001           
+23              , -0.0032361      , 0.001           
+24              , -0.000955756    , 0.001           
+25              , 0.00128953      , 0.001           
+26              , 0.00518424      , 0.001           
+27              , 0.0125712       , 0.001           
+28              , 0.0234942       , 0.001           
+29              , 0.0370801       , 0.001           
+30              , 0.052231        , 0.001           
+31              , 0.06787         , 0.001           
+32              , 0.0827503       , 0.001           
+33              , 0.0955927       , 0.001           
+34              , 0.105415        , 0.001           
+35              , 0.11154         , 0.001           
+36              , 0.113399        , 0.001           
+37              , 0.110583        , 0.001           
+38              , 0.103215        , 0.001           
+39              , 0.0921957       , 0.001           
+40              , 0.0789703       , 0.001           
+41              , 0.0650043       , 0.001           
+42              , 0.0514107       , 0.001           
+43              , 0.0389322       , 0.001           
+44              , 0.0280921       , 0.001           
+45              , 0.0192441       , 0.001           
+46              , 0.0124768       , 0.001           
+47              , 0.00752972      , 0.001           
+48              , 0.00391057      , 0.001           
+49              , 0.00131276      , 0.001