Development of a nuclear power plant safety and cyber security combined risk analysis method based on probabilistic safety assessment

Abstract

Since the 1980s, risk analysis of nuclear power plants has considered external threats and human errors. However, cyber threats have not been considered. In this dissertation, a method to calculate the combined safety–cybersecurity risk by considering cyber threats to be external threats is proposed. The proposed method was applied to the probabilistic safety analysis of a currently operational nuclear power plant to calculate the combined risk of each exponent of cyber threat frequency. The frequency of each cyber threat was estimated through Bayesian updates based on the operating experience of various industrial control systems. Then, these frequencies were applied to the developed method to confirm the effectiveness of the proposed methodology and security control in effectively blocking each cyber threat.