Time-Dependent Evaluation of Station Blackout and FLEX Integration in a Newcomer Nuclear Program: A Case Study of Uganda

This study presents a time-dependent probabilistic risk assessment of Station Blackout (SBO) for a newcomer nuclear program, in this case Uganda’s prospective first nuclear power plant, with emphasis on the role of Flexible and Diverse Coping Strategies (FLEX) in mitigating AC power loss. The model developed incorporates exponentially distributed fail-to-run rates for Emergency Diesel Generators (EDGs) and Alternate AC (AAC) sources and applies a Weibull distribution to model offsite power recovery, reflecting the country’s infrastructural constraints and grid reliability challenges. Two operational scenarios are analyzed: (1) reliance solely on AC-based power sources and (2) inclusion of a Turbine-Driven Pump (TDP) as a non-AC coping mechanism. In both cases, FLEX is assumed to be integrated after initial commercial operation and functions as a portable AC supply. Results indicate that timely FLEX deployment substantially reduces SBO risk, with the largest benefit at longer mission times. Sensitivity analysis reveals that equipment reliability dominates deployment timing effects, with high-reliability systems achieving up to 75% risk reduction, while low-reliability equipment provides limited improvement below 25%. These findings provide a quantified risk perspective for Uganda’s nuclear safety planning and support evidence-based decisions on post-startup integration, infrastructure investment, and emergency preparedness.