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2026 Nuclear Energy Conference & Expo (NECX)
August 24–27, 2026
Dallas, TX|Hilton Anatole
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The human factor in licensing and operating the next generation of nuclear plants
As human factors specialists working at the intersection of human performance and nuclear operations, we are witnessing one of the nuclear sector’s most significant transitions in decades. The emergence of small modular reactors, microreactors, and other advanced designs is reshaping the industry’s landscape. Digital instrumentation and controls, passive safety systems, and increased automation are creating opportunities for greater safety margins and more flexible operation. These same features also fundamentally redefine what it means to “operate” a nuclear plant. Interactions among human roles, automation, and passive systems shape how people maintain awareness, exercise judgment, and intervene when necessary. These developments affect both operational realities and the regulatory foundations on which nuclear safety is built.
As vice president of nuclear strategy & development for Exelon, Marilyn Kray leads major initiatives on current and advanced reactor designs to create growth opportunities that leverage Exelon’s nuclear operations competency. These initiatives include pursuing operational service agreements, both domestically and internationally, as well as engaging with advanced reactor developers in order to evaluate potential business opportunities and future technology deployment.
She served as president of NuStart Energy Development LLC, an industry consortium formed to develop the process for preparing the combined construction and operating license applications for the first new nuclear plant construction in the United States in over 30 years.
Her in-depth knowledge of the global nuclear industry comes from years of experience including as vice president of Exelon Nuclear Partners. In this role, she led international business development. Prior to this, she served as Exelon’s vice president of nuclear acquisition support, where she pioneered internal processes for due diligence and plant transitions. The result was the successful purchases of the Three Mile Island, Clinton, and Oyster Creek generating stations. More recently, she led the acquisition of the FitzPatrick nuclear power plant.
Marilyn began her career with Exelon in the licensing organization for the Peach Bottom Atomic Power Station. Prior to joining Exelon, she was a reactor engineer and project manager for the U.S. Nuclear Regulatory Commission. She has testified in front of Congress on multiple occasions regarding nuclear development in the United States. Throughout her career Marilyn has served in leadership roles as Exelon’s representative to the Nuclear Energy Institute and the Electric Power Research Institute.
Marilyn has been a member of ANS since 2007 and serves in the Education, Training, and Workforce Development Division as well as the Operations and Power Division. In 2007, she received the American Nuclear Society’s Utility Leadership Award. Other recognitions Marilyn has received include the World Nuclear Association award for Distinguished Contribution to the Peaceful Use of Nuclear Technology, and under her leadership the NuStart organization was one of four finalists for the 2012 Edison Award.
Marilyn is a graduate of Carnegie-Mellon University, with a Bachelor of Science degree in Chemical Engineering.
Read Nuclear News from July 2019 for more on Marilyn.
