Assessment of two uncertainty quantification methods for source term analysis

Two methods of uncertainty quantification have been assessed for application to the source term analysis of Younggwang 3 and 4 using the MAAP 3.0B code. The two methods of uncertainty analysis, i.e., the response surface method and the Latin hypercube sampling method, produced slightly different results for the empirical distribution function of the CsI release fraction from the Younggwang reactor containment. In source term analysis, the response surface method has the relative merits in the importance and the sensitivity analyses: By this method, important qualitative information about the relation between the inputs and the outputs can be obtained. However, it is found that it is difficult to ascertain the accuracy of the response surface method. Also, when the approximate model is not suitable, the above advantages of the response surface method do not outweigh the loss in accuracy. In this case, the Latin hypercube method is superior to the response surface method: That is, the Latin Hypercube method is more readily executable without any prior procedure to obtain an approximate model