Index: Ringtoets/Piping/src/Ringtoets.Piping.Data/PipingCalculationScenario.cs
===================================================================
diff -u -r8323c6cbe3f292646a254938161e17c42d13d10c -rf7a9f7239374705ff1d732e9666c0cb62ebaafd0
--- Ringtoets/Piping/src/Ringtoets.Piping.Data/PipingCalculationScenario.cs	(.../PipingCalculationScenario.cs)	(revision 8323c6cbe3f292646a254938161e17c42d13d10c)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Data/PipingCalculationScenario.cs	(.../PipingCalculationScenario.cs)	(revision f7a9f7239374705ff1d732e9666c0cb62ebaafd0)
@@ -49,11 +49,11 @@
 
         public RoundedDouble Contribution { get; set; }
 
-        public RoundedDouble Probability
+        public RoundedDouble? Probability
         {
             get
             {
-                return SemiProbabilisticOutput != null ? SemiProbabilisticOutput.PipingProbability : (RoundedDouble) double.NaN;
+                return SemiProbabilisticOutput != null ? SemiProbabilisticOutput.PipingProbability : (RoundedDouble?) null;
             }
         }
     }