diff --git a/source/branches/CLASSV3/Model/Irradiation/IM_Matrix.cxx b/source/branches/CLASSV3/Model/Irradiation/IM_Matrix.cxx
index d6679a1ef948c4dcb86eeef495251e2d5407a805..649608a594169f661d3f20065b85449ac29ae9b6 100644
--- a/source/branches/CLASSV3/Model/Irradiation/IM_Matrix.cxx
+++ b/source/branches/CLASSV3/Model/Irradiation/IM_Matrix.cxx
@@ -51,7 +51,7 @@ EvolutionData IM_Matrix::GenerateEvolutionData(IsotopicVector isotopicvector, Ev
 {
 	DBGL
 	if(fFastDecay.size() == 0)
-		BuildDecayMatrix();
+		NuclearDataInitialization();
 
 
 	string ReactorType;
diff --git a/source/branches/CLASSV3/Model/Irradiation/IM_RK4.cxx b/source/branches/CLASSV3/Model/Irradiation/IM_RK4.cxx
index e8c614dd39adab4f60bfccaa0cbcd6b2e818c8a1..247f10ba781103674052085b69b473ec605ddc4e 100644
--- a/source/branches/CLASSV3/Model/Irradiation/IM_RK4.cxx
+++ b/source/branches/CLASSV3/Model/Irradiation/IM_RK4.cxx
@@ -66,7 +66,7 @@ EvolutionData IM_RK4::GenerateEvolutionData(IsotopicVector isotopicvector, Evolu
 	DBGL
 	if(fFastDecay.size() == 0)
 	{
-		BuildDecayMatrix();
+		NuclearDataInitialization();
 		fNVar = findex_inver.size();
 	}