UNIVERSITY PARK, Pa. — Stefano Terlizzi, J. Brennan Early Career Professor of Nuclear Engineering at Penn State and a joint appointee at Idaho National Laboratory (INL), was named to the American Nuclear Society’s 2025 40 Under 40 list. This honor recognizes rising leaders whose work is advancing the future of nuclear science and technology.
The ANS 40 Under 40 program highlights individuals making meaningful contributions across the nuclear sector, from advanced reactor development and fuel cycle innovation to policy, modeling and space applications. Terlizzi’s selection places him among a cohort of early-career professionals whose work is helping shape a new era for nuclear energy at a time of rapid technological and generational change.
Terlizzi, 35, leads research in multiphysics simulation for microreactors and advanced reactor systems. He developed the first simulation predicting hydrogen redistribution in microreactors and led advanced modeling and simulation tools developed by the U.S. Department of Energy’s (DOE) Nuclear Energy Advanced Modeling and Simulation (NEAMS) program for the Microreactor Applications Research Validation and Evaluation (MARVEL) reactor project. He also founded Penn State’s Computational Reactor Engineering and Analysis (CREA) Lab and contributes to modernizing reactor physics education as part of DOE-supported initiatives.
“I’m very proud to serve as a faculty member at Penn State while collaborating with INL,” Terlizzi said in an ANS article. “Both institutions have a strong tradition of civilian nuclear applications, and I enjoy working with bright, enthusiastic students and colleagues to advance the field.”
Terlizzi said his interest in nuclear science began at an early age in his hometown of Turin, Italy. At seven, he watched the science documentary “L’Universo,” featuring Piero Angela, which introduced him to nuclear propulsion and sparked a lifelong fascination with energy and space exploration.
Reflecting on his career, Terlizzi highlighted the importance of mentorship and collaboration.
“I’ve been lucky to learn from many outstanding mentors,” Terlizzi said. “Dan Kotlyar, my doctoral advisor at Georgia Tech, emphasized consistency and practical solutions. At INL, Mark DeHart set the standard for excellent mentorship, and professors like Elia Merzari, Jon Schwantes and Arthur Motta have been invaluable in helping me navigate academia.”
Terlizzi is a world-class reactor physicist, according to Merzari.
“He has integrated seamlessly into the Penn State nuclear engineering community,” Merzari said. “We are incredibly fortunate to have him among us. It has been wonderful to see him grow so quickly into a key member of our faculty, excelling in teaching, research and service.”
Terlizzi’s career combines technical innovation with educational leadership. Through the CREA Lab, he fosters research on advanced reactor design while preparing the next generation of reactor physicists and nuclear engineers. His work integrates cutting-edge computational modeling with hands-on training in reactor physics, providing students with unique opportunities to engage with DOE-supported initiatives.
Looking forward, Terlizzi said his goals include mentoring emerging talent in nuclear engineering and contributing to the realization of advanced reactor designs. His advice for others who wish to have an impact on the field is simple: “Keep doing your work with integrity, and your time will come,” he said.