Review of Margins Beyond Design Basis Earthquake

Abstract

Following the 2011 Fukushima earthquake and tsunami, available margins beyond the design basis earthquake (DBE) were questioned and required to be assessed by the nuclear industry. Provisions were required to be made to ensure that there are adequate margins in the nuclear power plant systems, structures and components (SSCs) to safely withstand beyond design basis earthquakes.This paper provides an overview of approaches taken to evaluate the available margins, the measures taken to enhance plant safety margins and the status of current recommended margins beyond DBE by the Canadian and international nuclear industry to cater for the beyond design basis earthquake also called Design Extension Conditions (DEC).