LAUSR

Abstract In the process of a best estimate plus uncertainty (BEPU) methodology implementation for nuclear power plant safety analyses, the verification and validation (V&V) process including the uncertainty quantification (UQ) of the used computer codes and plant models plays an essential role. From the technical point of view, a BEPU methodology must be based on fully verified and validated codes and models, with quantified key model uncertainties. From the regulatory point of view, the adequacy of the simulation codes and plant models for the intended BEPU application must be assessed through the VVUQ process. These high level requirements of VVUQ result in high-cost for BEPU methodology development, preventing wider applications. Pragmatic, graded applications and practices of VVUQ in the BEPU methodology development are needed to allow to take full benefit of BEPU applications.