Index: Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil.Test/Calculators/Assembly/FailureMechanismSectionAssemblyCalculatorStubTest.cs
===================================================================
diff -u -rb29487c198d87b176783f2396c2b59cd76b9f246 -ra21db24da55c7451299022b2424cca61164b047b
--- Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil.Test/Calculators/Assembly/FailureMechanismSectionAssemblyCalculatorStubTest.cs	(.../FailureMechanismSectionAssemblyCalculatorStubTest.cs)	(revision b29487c198d87b176783f2396c2b59cd76b9f246)
+++ Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil.Test/Calculators/Assembly/FailureMechanismSectionAssemblyCalculatorStubTest.cs	(.../FailureMechanismSectionAssemblyCalculatorStubTest.cs)	(revision a21db24da55c7451299022b2424cca61164b047b)
@@ -214,12 +214,7 @@
             FailureMechanismSectionAssembly assembly = calculator.AssembleDetailedAssessment(
                 random.NextEnumValue<DetailedAssessmentResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             Assert.AreEqual(1.0, assembly.Probability);
@@ -242,12 +237,7 @@
             FailureMechanismSectionAssembly assembly = calculator.AssembleDetailedAssessment(
                 random.NextEnumValue<DetailedAssessmentResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             Assert.AreSame(calculator.DetailedAssessmentAssemblyOutput, assembly);
@@ -287,12 +277,7 @@
             TestDelegate test = () => calculator.AssembleDetailedAssessment(
                 random.NextEnumValue<DetailedAssessmentResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             var exception = Assert.Throws<FailureMechanismSectionAssemblyCalculatorException>(test);
@@ -310,13 +295,8 @@
             // Call
             FailureMechanismSectionAssembly assembly = calculator.AssembleDetailedAssessment(
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                },
-                random.NextRoundedDouble(1.0, 10.0));
+                new FailureMechanismSectionAssemblyCategory[0],
+            random.NextRoundedDouble(1.0, 10.0));
 
             // Assert
             Assert.AreEqual(0.0, assembly.Probability);
@@ -338,13 +318,8 @@
             // Call
             FailureMechanismSectionAssembly assembly = calculator.AssembleDetailedAssessment(
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                },
-                random.NextRoundedDouble(1.0, 10.0));
+                new FailureMechanismSectionAssemblyCategory[0],
+            random.NextRoundedDouble(1.0, 10.0));
 
             // Assert
             Assert.AreSame(calculator.DetailedAssessmentAssemblyOutput, assembly);
@@ -384,13 +359,8 @@
             // Call
             TestDelegate test = () => calculator.AssembleDetailedAssessment(
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                },
-                random.NextRoundedDouble(1.0, 10.0));
+                new FailureMechanismSectionAssemblyCategory[0],
+            random.NextRoundedDouble(1.0, 10.0));
 
             // Assert
             var exception = Assert.Throws<FailureMechanismSectionAssemblyCalculatorException>(test);
@@ -413,12 +383,7 @@
             FailureMechanismSectionAssembly assembly = calculator.AssembleTailorMadeAssessment(
                 random.NextEnumValue<TailorMadeAssessmentProbabilityAndDetailedCalculationResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             Assert.AreEqual(1.0, assembly.Probability);
@@ -441,12 +406,7 @@
             FailureMechanismSectionAssembly assembly = calculator.AssembleTailorMadeAssessment(
                 random.NextEnumValue<TailorMadeAssessmentProbabilityAndDetailedCalculationResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             Assert.AreSame(calculator.TailorMadeAssessmentAssemblyOutput, assembly);
@@ -486,12 +446,7 @@
             TestDelegate test = () => calculator.AssembleTailorMadeAssessment(
                 random.NextEnumValue<TailorMadeAssessmentProbabilityAndDetailedCalculationResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             var exception = Assert.Throws<FailureMechanismSectionAssemblyCalculatorException>(test);
@@ -510,12 +465,7 @@
             FailureMechanismSectionAssembly assembly = calculator.AssembleTailorMadeAssessment(
                 random.NextEnumValue<TailorMadeAssessmentProbabilityCalculationResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             Assert.AreEqual(1.0, assembly.Probability);
@@ -538,12 +488,7 @@
             FailureMechanismSectionAssembly assembly = calculator.AssembleTailorMadeAssessment(
                 random.NextEnumValue<TailorMadeAssessmentProbabilityCalculationResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             Assert.AreSame(calculator.TailorMadeAssessmentAssemblyOutput, assembly);
@@ -583,12 +528,7 @@
             TestDelegate test = () => calculator.AssembleTailorMadeAssessment(
                 random.NextEnumValue<TailorMadeAssessmentProbabilityCalculationResultType>(),
                 random.NextDouble(),
-                new[]
-                {
-                    new FailureMechanismSectionAssemblyCategory(random.NextRoundedDouble(0.0, 0.5),
-                                                                random.NextRoundedDouble(0.6, 1.0),
-                                                                random.NextEnumValue<FailureMechanismSectionAssemblyCategoryGroup>())
-                });
+                new FailureMechanismSectionAssemblyCategory[0]);
 
             // Assert
             var exception = Assert.Throws<FailureMechanismSectionAssemblyCalculatorException>(test);
Index: Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil.Test/Kernels/Assembly/FailureMechanismSectionAssemblyKernelStubTest.cs
===================================================================
diff -u -r3199add8dbd09d0b4a9727fd6092ccc16d86563c -ra21db24da55c7451299022b2424cca61164b047b
--- Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil.Test/Kernels/Assembly/FailureMechanismSectionAssemblyKernelStubTest.cs	(.../FailureMechanismSectionAssemblyKernelStubTest.cs)	(revision 3199add8dbd09d0b4a9727fd6092ccc16d86563c)
+++ Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil.Test/Kernels/Assembly/FailureMechanismSectionAssemblyKernelStubTest.cs	(.../FailureMechanismSectionAssemblyKernelStubTest.cs)	(revision a21db24da55c7451299022b2424cca61164b047b)
@@ -96,10 +96,11 @@
         public void SimpleAssessmentDirectFailureMechanisms_ThrowExceptionOnCalculateFalse_ReturnFailureMechanismSectionAssemblyCategoryResult()
         {
             // Setup
+            var random = new Random(39);
             var kernel = new FailureMechanismSectionAssemblyKernelStub
             {
                 FailureMechanismSectionAssemblyCategoryResult = new CalculationOutput<FailureMechanismSectionAssemblyCategoryResult>(
-                    new FailureMechanismSectionAssemblyCategoryResult(FailureMechanismSectionCategoryGroup.IIIv, Probability.NaN))
+                    new FailureMechanismSectionAssemblyCategoryResult(random.NextEnumValue<FailureMechanismSectionCategoryGroup>(), Probability.NaN))
             };
 
             // Call
@@ -166,10 +167,11 @@
         public void SimpleAssessmentDirectFailureMechanismsValidityOnly_ThrowExceptionOnCalculateFalse_ReturnFailureMechanismSectionAssemblyCategoryResult()
         {
             // Setup
+            var random = new Random(39);
             var kernel = new FailureMechanismSectionAssemblyKernelStub
             {
                 FailureMechanismSectionAssemblyCategoryResult = new CalculationOutput<FailureMechanismSectionAssemblyCategoryResult>(
-                    new FailureMechanismSectionAssemblyCategoryResult(FailureMechanismSectionCategoryGroup.IIIv, Probability.NaN))
+                    new FailureMechanismSectionAssemblyCategoryResult(random.NextEnumValue<FailureMechanismSectionCategoryGroup>(), Probability.NaN))
             };
 
             // Call
@@ -287,7 +289,7 @@
             var kernel = new FailureMechanismSectionAssemblyKernelStub
             {
                 FailureMechanismSectionAssemblyCategoryResult = new CalculationOutput<FailureMechanismSectionAssemblyCategoryResult>(
-                    new FailureMechanismSectionAssemblyCategoryResult(FailureMechanismSectionCategoryGroup.IIIv, Probability.NaN))
+                    new FailureMechanismSectionAssemblyCategoryResult(random.NextEnumValue<FailureMechanismSectionCategoryGroup>(), Probability.NaN))
             };
 
             // Call
@@ -604,7 +606,11 @@
             var detailedAssemblyResult = random.NextEnumValue<FailureMechanismSectionCategoryGroup>();
             var tailorMadeAssemblyResult = random.NextEnumValue<FailureMechanismSectionCategoryGroup>();
 
-            var kernel = new FailureMechanismSectionAssemblyKernelStub();
+            var kernel = new FailureMechanismSectionAssemblyKernelStub
+            {
+                FailureMechanismSectionAssemblyCategoryGroup = new CalculationOutput<FailureMechanismSectionCategoryGroup>(
+                    random.NextEnumValue<FailureMechanismSectionCategoryGroup>())
+            };
 
             // Call
             CalculationOutput<FailureMechanismSectionCategoryGroup> result = kernel.CombinedAssessmentFromFailureMechanismSectionResults(
@@ -687,7 +693,11 @@
                 random.NextEnumValue<FailureMechanismSectionCategoryGroup>(),
                 Probability.NaN);
 
-            var kernel = new FailureMechanismSectionAssemblyKernelStub();
+            var kernel = new FailureMechanismSectionAssemblyKernelStub
+            {
+                FailureMechanismSectionAssemblyCategoryResult = new CalculationOutput<FailureMechanismSectionAssemblyCategoryResult>(
+                    new FailureMechanismSectionAssemblyCategoryResult(random.NextEnumValue<FailureMechanismSectionCategoryGroup>(), Probability.NaN))
+            };
 
             // Call
             CalculationOutput<FailureMechanismSectionAssemblyCategoryResult> result = kernel.CombinedAssessmentFromFailureMechanismSectionResults(
Index: Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil/Calculators/Assembly/FailureMechanismSectionAssemblyCalculatorStub.cs
===================================================================
diff -u -r5180f3c52adce7b8214e51b81b0ad8c7b21f4521 -ra21db24da55c7451299022b2424cca61164b047b
--- Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil/Calculators/Assembly/FailureMechanismSectionAssemblyCalculatorStub.cs	(.../FailureMechanismSectionAssemblyCalculatorStub.cs)	(revision 5180f3c52adce7b8214e51b81b0ad8c7b21f4521)
+++ Ringtoets/AssemblyTool/test/Ringtoets.AssemblyTool.KernelWrapper.TestUtil/Calculators/Assembly/FailureMechanismSectionAssemblyCalculatorStub.cs	(.../FailureMechanismSectionAssemblyCalculatorStub.cs)	(revision a21db24da55c7451299022b2424cca61164b047b)
@@ -120,7 +120,7 @@
         /// <summary>
         /// Gets or sets the output of the combined assembly calculation.
         /// </summary>
-        public FailureMechanismSectionAssemblyCategoryGroup CombinedAssemblyCategoryOutput { get; set; }
+        public FailureMechanismSectionAssemblyCategoryGroup? CombinedAssemblyCategoryOutput { get; set; }
 
         /// <summary>
         /// Gets the simple assembly input of the combined assembly calculation.
@@ -270,7 +270,11 @@
             CombinedDetailedAssemblyGroupInput = detailedAssembly;
             CombinedTailorMadeAssemblyGroupInput = tailorMadeAssembly;
 
-            return CombinedAssemblyCategoryOutput = tailorMadeAssembly;
+            if (CombinedAssemblyCategoryOutput == null)
+            {
+                CombinedAssemblyCategoryOutput = tailorMadeAssembly;
+            }
+            return CombinedAssemblyCategoryOutput.Value;
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/Integration/test/Ringtoets.Integration.Data.Test/StandAlone/AssemblyFactories/MacroStabilityOutwardsFailureMechanismSectionResultAssemblyFactoryTest.cs
===================================================================
diff -u -rb29487c198d87b176783f2396c2b59cd76b9f246 -ra21db24da55c7451299022b2424cca61164b047b
--- Ringtoets/Integration/test/Ringtoets.Integration.Data.Test/StandAlone/AssemblyFactories/MacroStabilityOutwardsFailureMechanismSectionResultAssemblyFactoryTest.cs	(.../MacroStabilityOutwardsFailureMechanismSectionResultAssemblyFactoryTest.cs)	(revision b29487c198d87b176783f2396c2b59cd76b9f246)
+++ Ringtoets/Integration/test/Ringtoets.Integration.Data.Test/StandAlone/AssemblyFactories/MacroStabilityOutwardsFailureMechanismSectionResultAssemblyFactoryTest.cs	(.../MacroStabilityOutwardsFailureMechanismSectionResultAssemblyFactoryTest.cs)	(revision a21db24da55c7451299022b2424cca61164b047b)
@@ -571,7 +571,7 @@
                         assessmentSection);
 
                 // Assert
-                FailureMechanismSectionAssemblyCategoryGroup calculatorOutput = calculator.CombinedAssemblyCategoryOutput;
+                FailureMechanismSectionAssemblyCategoryGroup? calculatorOutput = calculator.CombinedAssemblyCategoryOutput;
                 Assert.AreEqual(calculatorOutput, actualOutput);
                 mocks.VerifyAll();
             }