Index: Riskeer/Piping/src/Riskeer.Piping.IO/Configurations/PipingCalculationConfigurationReader.cs
===================================================================
diff -u -r86c3749da5879489a30004027e1ac6782cec97e8 -rb61271be62aa1d5c88973d1136b74eb8fc60b181
--- Riskeer/Piping/src/Riskeer.Piping.IO/Configurations/PipingCalculationConfigurationReader.cs	(.../PipingCalculationConfigurationReader.cs)	(revision 86c3749da5879489a30004027e1ac6782cec97e8)
+++ Riskeer/Piping/src/Riskeer.Piping.IO/Configurations/PipingCalculationConfigurationReader.cs	(.../PipingCalculationConfigurationReader.cs)	(revision b61271be62aa1d5c88973d1136b74eb8fc60b181)
@@ -88,10 +88,13 @@
                     }, Resources.PipingConfiguratieSchema0To1)
             }) {}
 
+        /// <inheritdoc />
+        /// <exception cref="NotSupportedException">Thrown when the value of
+        /// <see cref="PipingCalculationConfigurationType"/> is not supported.</exception>
         protected override PipingCalculationConfiguration ParseCalculationElement(XElement calculationElement)
         {
             return new PipingCalculationConfiguration(calculationElement.Attribute(ConfigurationSchemaIdentifiers.NameAttribute).Value,
-                GetCalculationType(calculationElement).Value)
+                                                      GetCalculationType(calculationElement))
             {
                 AssessmentLevel = calculationElement.GetDoubleValueFromDescendantElement(PipingCalculationConfigurationSchemaIdentifiers.WaterLevelElement),
                 HydraulicBoundaryLocationName = calculationElement.GetStringValueFromDescendantElement(ConfigurationSchemaIdentifiers.HydraulicBoundaryLocationElement),
@@ -108,19 +111,26 @@
             };
         }
 
-        private static PipingCalculationConfigurationType? GetCalculationType(XElement calculationElement)
+        /// <summary>
+        /// Gets the type of the calculation.
+        /// </summary>
+        /// <param name="calculationElement">The read calculation element to parse.</param>
+        /// <returns>A <see cref="PipingCalculationConfigurationType"/>.</returns>
+        /// <exception cref="NotSupportedException">Thrown when the value of
+        /// <see cref="PipingCalculationConfigurationType"/> is not supported.</exception>
+        private static PipingCalculationConfigurationType GetCalculationType(XElement calculationElement)
         {
             if (calculationElement.GetDescendantElement(PipingCalculationConfigurationSchemaIdentifiers.SemiProbabilistic) != null)
             {
                 return PipingCalculationConfigurationType.SemiProbabilistic;
             }
-            
+
             if (calculationElement.GetDescendantElement(PipingCalculationConfigurationSchemaIdentifiers.Probabilistic) != null)
             {
                 return PipingCalculationConfigurationType.Probabilistic;
             }
 
-            return null;
+            throw new NotSupportedException();
         }
     }
 }
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