BEPU Approach in the CANDU 6 Severe Accident Analysis

Abstract

The worst nuclear accident after Cernobil (in April 1986), the Fukushima Daichii accident from March 11th, 2011 has increased nuclear experts interest, all over the world, on the implementation of severe accident management measures in order to maintain the integrity of the safety barriers. Even though CANDU (CANada Deuterium Uranium) reactors are different from BWRs (Boiling Water Reactors), the effect of an unmitigated SBO (Station BlackOut) accident could turn into a real challenge for the plant's components and systems, but also for the environment and population. The present paper includes a BEPU (Best Estimate Plus Uncertainty) approach of a SBO using RELAP/SCDAPSIM best estimate tool with the integrated uncertainty analysis package implemented in the code considering an alternative measure to mitigate the severe accident progression, based on the previous studies reported by UPB.The purpose of this study is to determine the latest severe accident management measure to be implemented that could prevent the fuel channel failure during the early phase of a Station BlackOut analysis for a CANDU 6 reactor, when uncertainties are considered. Assessing and reviewing continuously the safety related issues from severe accident scenarios to determine whether the management measures implemented comply with the applicable safety objectives and requirements is essential to achieve and maintain a high level of safety in nuclear reactors. The present work could be helpful in the area of the regulatory requirements in case of severe accidents, in the development of SAMG (Severe Accident Management Guidelines).