A non-parametric cumulative sum approach for online diagnostics of cyber attacks to nuclear power plants

Both stochastic failures and cyber attacks can compromise the correct functionality of Cyber-Physical Systems (CPSs). Cyber attacks manifest themselves in the physical system and, can be misclassified as component failures, leading to wrong control actions and maintenance strategies. In this chapter, we illustrate the use of a nonparametric cumulative sum (NP-CUSUM) approach for online diagnostics of cyber attacks to CPSs. This allows for (i) promptly recognizing cyber attacks by distinguishing them from component failures, and (ii) guiding decisions for the CPSs recovery from anomalous conditions. We apply the approach to the Advanced Lead-cooled Fast Reactor European Demonstrator (ALFRED) and its digital Instrumentation and Control (I&C) system. For this, an object-oriented model previously developed is embedded within a Monte Carlo (MC) engine that allows injecting into the I&C system both components (stochastic) failures (such as sensor bias, drift, wider noise and freezing) and cyber attacks (such as Denial of Service (DoS) attacks mimicking component failures).