Risk management of NPPs using risk monitors

Abstract

In nuclear power plants (NPPs), safety is the major concern. Probabilistic safety assessment (PSA) has become a key tool as on today to identify and understand NPP vulnerabilities. PSA models have been successfully employed during design evaluation to assess weak links and carry out design modifications to improve system reliability and safety. As a result of the availability of these PSA studies, one can make use of them to enhance plant safety and to operate the plants in the most efficient manner. This necessitates development of software tools like living PSA, risk monitor etc. Risk monitor is a PC based tool, which computes the real time safety level based on the actual status of systems and components and assists plant personnel and regulatory authorities to manage day-to-day activities and can provide solutions to various regulatory decision making issues. This paper discusses various modules and data flow diagrams of risk monitor and also discusses how common cause failures are treated in risk monitor. In risk monitor, risk is subjected to the change in the state of the system, which in turn depends on the state of the components and these are explained with a case study.