Askin Guler Yigitoglu (yigitoglua@ornl.gov) is a reactor systems modeling and safety analysis staff member at ORNL, chair of ANS’s Nuclear Installations Safety Division, and technical program chair for the PSA 2023 conference.

Probabilistic risk assessment is a mature technology that has benefited the safety of the current fleet of light water reactors in the United States since the 1970s. Most utilities have used PRA models as part of risk-informed in-service inspection programs to identify degraded plant conditions for more than two decades. The trends indicate an increasing use of risk-informed applications to support safe and cost-effective long-term operations.

Data science and predictive analytics innovations offer the opportunity to assess, monitor, and manage risk effectively. PRA models are coupled with digital twins informed by sensors and system simulators that provide real-time risk insights. Dynamic PRA approaches were initially introduced to beyond-design-basis event models for LWRs and explicitly model time-dependent operator behavior by simulating the actual plant response. Enhancing the quantification speed and memory usage of the PRA computational tools (both dynamic and traditional) is crucial for future risk-informed efforts.

As the U.S. nuclear industry moves into plant life extension and subsequent license renewals, the modernization of safety instrumentation and control (I&C) systems holds significant potential to transform plant operations. Automated system diagnostics, equipment health monitoring, and performance indications reduce the need for manual surveillance activities and enable condition-based maintenance, resulting in improved system reliability and reduced maintenance costs. Despite these benefits, adoption of digital I&C systems for safety-related applications across the domestic nuclear fleet has been slow. U.S. nuclear power plants that do choose to embrace the transition from analog to digital are in good company; international plants have successfully implemented digital safety systems for more than a decade. Furthermore, digital safety systems are also the first choice of the growing small modular reactor (SMR) and advanced reactor (AR) communities.