Beyond Probabilities
On March 11, 2011, the devastating magnitude 9.1 Tōhoku earthquake and tsunami struck Japan, leading to a catastrophic accident at the Fukushima Daiichi Nuclear Plant. A week after the disaster, the tap water in Tokyo, where Tatsuya Sakurahara was pursuing his master’s degree, was contaminated. The experience left an indelible mark on Sakurahara and focused his research on risk analysis of nuclear energy facilities.
Now an assistant professor in the Department of Mechanical Engineering and Materials Science at the University of Pittsburgh Swanson School of Engineering, Sakurahara continues to advance how risk is assessed in complex systems. This May, he received a 2026 Oak Ridge Associated Universities (ORAU) Ralph E. Powe Junior Faculty Enhancement Award of $5,000 to develop a computational risk-assessment tool for nuclear facilities.
As many countries increasingly turn to nuclear power for cleaner energy, Sakurahara’s research seeks to help keep nuclear plants safer and running more efficiently.
“Traditionally, we have used probabilities to represent uncertainty. But incredible events like those that led to the Fukushima Daiichi disaster reveal the limitations of probabilistic modeling, especially if we lack sufficient data,” said Sakurahara, who also directs the Risk Analysis and Reliability Engineering (RARE) Laboratory. “We need a multi-disciplinary, multi-faceted approach to better understand and model uncertainties in complex systems.”
To build his framework, Sakurahara will begin by reviewing and assessing theories and methods used in fields such as information sciences and computational sciences. He will apply new theories and build upon his research to develop a prototype that combines multiple methods.
“We use systems modeling to understand how the different components in a plant interrelate, but then we must look at each component specifically using hardware reliability models,” Sakurahara said. “There is also a human element, which requires human reliability models so we can estimate the likelihood and the consequences of human failures.”
The framework will integrate probabilistic and non-probabilistic uncertainty theories and methods to characterize uncertainties associated with these models.
Sakurahara will combine these methods to more effectively answer the essential risk-assessment questions of what can go wrong, how likely it is to go wrong, and what are the consequences. To demonstrate the prototype, he will test it against other methods using the Fukushima Daiichi disaster as a case study.
“I’m honored to receive this award and to have the opportunity to visit the Oak Ridge National Lab and learn from experts there,” said Sakurahara.
Each year, ORAU recognizes junior faculty members across five STEM-related disciplines with Ralph E. Powe Junior Faculty Enhancement Awards. This year, 172 researchers applied, and Sakurahara was one of 36 awardees. Pitt will match the $5,000 award, providing seed funding to help launch a larger research project.
For Sakurahara, that project will be inspired by his experiences in Tokyo immediately after the Fukushima Daiichi nuclear accident following the terrible earthquake and tsunami. He will continue to discover new ways to assess multiple dimensions of risk to determine the optimal way of operating nuclear power plants.