Safety assessment for internal and external events on nuclear power plants and on mitigation strategies

This paper describes the main objectives and outcomes of two funded European projects (R2CA & BESEP), which have been recently finalized. They were dedicated to the safety analyses of design basis accidents and design extension conditions scenarios, covering a broad spectrum of accidents and analysis methodologies. The R2CA project covering deterministic safety analyses set out to reduce some of the conservatisms and decoupling factors currently used for design basis accidents in safety studies or licensing calculations and to optimize emergency operating/accident management procedures. To this end, simulation tools and their coupling in calculation chains were enhanced to provide a better quantification of safety margins and a better evaluation of the radiological consequences of accident scenarios. The BESEP project aims to develop best practices for the verification of stringent safety requirements against external hazards. The aim is achieved using an efficient and integrated set of safety engineering practices and probabilistic safety assessment. The efficient and integrated set of safety engineering practices supports the safety margins determination and safety requirement verification helping the licensing process of nuclear power plant new builds and upgrades.