Atomic Safety and Licensing Board Panel Members

Select a Panel member's name to view a qualifications summary.

*Full Time Panel Member

Sue H. Abreu

B.S.E., Purdue University 
M.D., Uniformed Services University of the Health Sciences 
J.D., Oklahoma City University 

Dr. Abreu is an engineer, nuclear medicine physician, and attorney who was appointed as a part-time technical judge in 2015 and as a full-time judge in 2016. She was Associate Chief Administrative Judge (Technical) from 2019 to 2025. A retired Colonel, she served in multiple positions during her twenty-four-year United States Army career, including as the Nuclear Medicine Consultant to the Army Surgeon General. Dr. Abreu led the American College of Nuclear Physicians as President from 2001 to 2002 and was President of the Board of Directors of the Intersocietal Accreditation Commission Nuclear/PET Division from 2009 to 2011. A Fellow of the American College of Nuclear Medicine, Dr. Abreu was recognized with its Lifetime Achievement Award in 2011. Purdue University honored her as an Outstanding Interdisciplinary Engineer in 2001 and as a Distinguished Engineering Alumna in 2020. Purdue inducted her into the Tri-Service ROTC Hall of Fame in 2004. The U.S. Department of Commerce's Malcolm Baldrige National Quality Program selected Dr. Abreu as an Examiner in 2006. Dr. Abreu has co-authored numerous medical publications and is often invited to speak at nuclear medicine conferences.

Gary S. Arnold

B.S., Math, Rensselaer Polytechnic Institute
M.S., Nuclear Engineering, Rensselaer Polytechnic Institute
M.S., Math, Rensselaer Polytechnic Institute
Ph.D., Nuclear Engineering, Rensselaer Polytechnic Institute

Dr. Arnold was appointed to the Panel as a full-time technical judge in 2008. In his 20 years at Knolls, his major fields of interest included analysis of two-phase flow stability, development of real-time simulation models of advanced/innovative reactor plant designs, realistic evaluations of plant transients, containment thermal hydraulics, and severe accident analysis. He has also acted as liaison with reactor safety engineers in the UK submarine design community. After completing Naval Nuclear Power School in 1977, Dr. Arnold served as an engineering officer aboard a fleet ballistic missile nuclear submarine until his release from active service in 1980. From 1981 to 1983, he worked as a startup engineer during fuel load, initial criticality, physics testing, and power ascension testing at San Onofre Nuclear Generating Station.

Anthony J. Baratta

A.B., B.S., Columbia University
M.S., Ph.D., Brown University

Dr. Baratta is a part-time technical member of the Panel. He formerly served as the Associate Chief Administrative Judge (Technical) retiring in January 2014. Before his appointment to the Panel in 2003, he served as professor of nuclear engineering at Penn State. While at Penn State he headed the Nuclear Safety Center, served as the chair of the Nuclear Engineering program, taught graduate and undergraduate courses, and supervised numerous M.S. and Ph.D. theses in nuclear engineering and physics. Dr. Baratta is the author of three books: an introductory nuclear engineering text, Introduction to Nuclear Engineering, co-authored with the late J.R. Lamarsh, a historic account of the accident at Three Mile Island, TMI 25 Years Later: The Three Mile Island Nuclear Power Plant Accident and Its Impact, co-authored with T.W. Conkling and B.A. Osif, and Climate Change: The Technology Challenge, F. Princiotta (Ed.), Springer, 2011. His prior Federal service includes 30 years in the Naval Reserve where he rose to the rank of Captain as well as service with the Division of Naval Reactors, U.S. DOE. Dr. Baratta has served as a consultant on nuclear safety in the U.S. and abroad. He is the author of numerous technical articles on thermal hydraulics, reactor kinetics, and reactor safety. He holds two patents and is active in a number of professional societies.

G. Paul Bollwerk, III

B.A., University of Notre Dame 
J.D., Georgetown University Law Center 

Judge Bollwerk was appointed as a part-time judge in May 2025 after retiring from his July 1991 to May 2025 Panel service as a full-time legal judge, which included service as Chief Administrative Judge from January 1999 through June 2006.  Before being appointed to the Licensing Board Panel, Judge Bollwerk served as an administrative judge on the Atomic Safety and Licensing Appeal Panel, a senior attorney in the NRC Office of the General Counsel, a special assistant U.S. attorney with the Department of Justice, and an associate attorney in the law firm of Gardner Carton & Douglas in Washington, D.C.  After graduating from law school, he clerked for a federal district court judge and a state supreme court judge. Judge Bollwerk also has served on the faculty of the National Judicial College as a lecturer on managing complex cases and courtroom technology.

Dawna L. Cerney

B.S., Geography, University of Lethbridge
M.S., Environmental Science, University of Calgary
Ph.D., Environmental Geography, Texas State University

Dr. Cerney was appointed to the Panel as a part-time technical judge in 2026. She is a Professor of Environmental Geography at Youngstown State University and serves as Executive Director of the Applied Geography Conference (AGX: A Community of Applied Geography). She is a member of the editorial board of the Annals of the American Association of Geographers and serves as Associate Editor of Papers in Applied Geography. Her research examines ecosystem responses to climate variability, land-use change, natural hazards, and human activity. In addition to her ecosystems research, Dr. Cerney is an award-winning research affiliate who works with municipalities in western Pennsylvania and southeastern Ohio to advance community revitalization and stability through a place-based, interdisciplinary approach.

Diane D. Di Massa

B.S.M.E., Massachusetts Institute of Technology
M.S.M.E., Massachusetts Institute of Technology
Mechanical Engineer Degree, Massachusetts Institute of Technology
Ph.D., Massachusetts Institute of Technology and Woods Hole Oceanographic Institution Joint Program in Oceanography and Oceanographic Engineering

Dr. Di Massa was appointed to the Panel as a part-time technical judge in 2024. She is currently a Professor of Engineering at the Massachusetts Maritime Academy (MMA), where she teaches a broad range of undergraduate courses. She created the Energy Systems Engineering undergraduate degree at MMA and served as the first program administrator. Prior to her appointment at MMA, she served as faculty in the Mechanical Engineering Department of the University of Massachusetts Dartmouth. She has a diverse background that includes environmental engineering/monitoring as well as scientific/engineering activities in planetary science, biological oceanography, geology, marine robotics, ocean-going instrumentation, and alternative/renewable energy. Some of her work has been sponsored by NATO. Dr. Di Massa has volunteered with the Institute of Electrical and Electronics Engineers Oceanic Engineering Society, providing her expertise on committees, presenting at conferences, and serving in leadership roles. She was the first American woman to earn the organization’s international Distinguished Service Award. She is also a recipient of the United States Antarctic Service Medal for research supported by the National Science Foundation.

William J. Froehlich

B.A., Harpur College, SUNY @ Binghamton
J.D., Brooklyn Law School

Judge Froehlich was appointed as a part-time legal judge in January 2023. From March 2008 until December 2022, he served as a full-time legal member of the Panel. Previously, Judge Froehlich was a member of the senior executive service at the Federal Energy Regulatory Commission. He held a number of key leadership positions during his 32-year career at FERC, including Director of the Office of Administrative Litigation, Special Counsel to the Office of Enforcement, Assistant General Counsel for Gas and Oil Litigation and Director of the Financial Regulation Division. He oversaw the agency's trial staff in the adjudication of natural gas, oil pipeline, and electric utility rate cases. He also handled cases involving the importation of liquefied natural gas, the rates and charges for newly constructed pipelines, and the prosecution of cases arising from the Enron trading schemes. He represented the agency and the United States in China and throughout Eastern Europe, where he has lectured foreign regulators and taught classes on administrative law, the privatization of state-owned industries, public utility ratemaking, and the development of independent regulatory structures. Judge Froehlich continues to teach at George Mason University, where he is an adjunct professor of administrative law.

Michael M. Gibson

B.A., University of Oklahoma
J.D., University of Oklahoma College of Law

Judge Gibson was appointed to the Panel as a full time legal member in July 2008. Previously, Judge Gibson served as lead trial counsel in complex environmental and toxic tort litigation for both private companies and the Environmental Protection Agency during a span of thirty years. The Chambers US Directory, which lists the top lawyers in the United States based on independent professional research, listed Judge Gibson as an expert in the field of environmental law. Judge Gibson also taught environmental law and policy as an adjunct professor. He has published numerous law review articles on environmental law, as well as a treatise, Environmental Regulation of Petroleum Spills and Wastes (John Wiley & Sons 1993; supp. 1994; Supp. 1995). His legal experience includes serving with the U.S. Environmental Protection Agency (1975-1982), the U.S. Justice Department (1983-1987), and as a partner with several law firms including Jones Day (1987-2008).

E. Roy Hawkens

B.S., United States Naval Academy
J.D., College of William & Mary Marshall-Wythe Law School

Judge Hawkens has been a full-time legal member of the Panel since September 2004, and he was appointed Chief Administrative Judge on July 1, 2006. After graduating from the Naval Academy in 1975, he served as a nuclear engineering division officer aboard a submarine and as a radiological controls officer aboard a submarine tender. He left active duty Naval Service in 1980, but he remained in the Naval Reserve, where he attained the rank of Captain. Upon graduating from law school, where he was Order of the Coif and managing editor of the Law Review, he clerked for Judge Tamm on the U.S. Court of Appeals for the District of Columbia Circuit. In 1985, he joined the Department of Justice where, as a litigator on the Appellate Staff of the Civil Division, he represented the Federal Government in the U.S. Courts of Appeals.

Yassin A. Hassan

B.S., Engineering, University of Alexandria
M.S., Nuclear Engineering, University of Illinois
M.S., Mechanical Engineering, University of Virginia
Ph.D., Nuclear Engineering, University of Illinois

Dr. Hassan was appointed to the Panel as a part-time technical judge in 2007. He is Professor and Associate Department Head of the Department of Nuclear Engineering and also Professor of the Department of Mechanical Engineering at Texas A&M University. Prior to joining A&M September 1986, he worked for seven years at Babcock & Wilcox Company, Virginia. His research is in thermal hydraulics, reactor safety, accident analyses, advanced nuclear reactors and aerosol dynamics. He is a fellow of both ANS and ASME, and awarded 2003 George Westinghouse Gold Medal award, 2004 Thermal Hydraulics Technical Achievement award and 2001 Glenn Murphy award of the American Association for Engineering Education. He is the editor-in-chief of the Nuclear Engineering and Design Journal. He supported NRC's research division in certification of AP600, ARC 700 and participated in the Phenomena Identification and Ranking Table panel of high temperature gas cooled reactors.

William E. Kastenberg

B.S., Engineering, UCLA
M.S., Engineering, UCLA
Ph.D., Nuclear Engineering, University of California at Berkeley

Dr. Kastenberg was appointed to the Panel as a part-time technical judge in 2007. For the previous 41 years he was a Professor in the University of California System, first at UCLA (1966-1994) and then at Berkeley (1995-2007), where he retired as the Daniel M. Tellep Distinguished Professor of Engineering. In 1990, he was appointed by the Governor of California to the Independent Safety Committee for the Diablo Canyon Nuclear Power Plant, and served for 10 years. Dr. Kastenberg has taught courses on risk assessment and management for engineered and environmental systems, engineering ethics, nuclear reactor analysis and safety, energy and the environment, and applied mathematics. His research interests include the development and application of risk assessment and risk management methods for complex technological and natural environmental systems. More recently, he has focused on ethics and the impact of technology on society, multi-stakeholder decision-making, the development of new paradigms for defining the risk of complex systems, and the quantification of uncertainty. Dr. Kastenberg has authored or co-authored over 150 published papers in peer-reviewed journals and conference proceedings. He was elected to the National Academy of Engineering in 1997, and was elected a Fellow of the American Association for the Advancement of Science in 1990 and the American Nuclear Society in 1978. He has won distinguished teaching awards from the American Society for Engineering Education, the Engineering Graduate Students' Association at UCLA, and the American Nuclear Society.

Michael F. Kennedy

B.S., Physics, Canisius College
M.S., Nuclear Engineering, University of Virginia
Ph.D., Nuclear Engineering, University of Virginia

Dr. Kennedy is a part time technical judge.  He was appointed as a full-time technical judge in January 2008. In January 2014, he was appointed Associate Chief Administrative Judge (Technical), retiring in 2018. Previously, he worked for over 30 years in the nuclear industry with a primary focus on licensing and safety analysis for current generation light water reactors, advanced reactor designs, and fuel cycle facilities. During his career, he worked for various nuclear consulting companies, nuclear utility organizations, reactor vendors, and Argonne National Laboratory, holding positions of technical leadership or management. He has provided technical support to the NRC in the license renewal area, performed safety analysis reviews for NRR, and updated regulatory guidance documents for RES and NMSS. Prior to this, he performed Integrated Safety Assessments for a number of fuel cycle facilities as well as supporting development of a centrifuge enrichment facility license application. He was a guest lecturer in light water reactor safety analysis for a course in Dubrovnik sponsored by the International Center for Heat and Mass Transfer. He has authored technical papers on nuclear safety and the application of information technology to managing configuration data for nuclear power plants.

Emily I. Krause

B.A., University of Virginia
J.D., Catholic University of America, Columbus School of Law
 
Judge Krause was appointed to the Panel as a full-time legal judge in October 2023. In December 2024, she was appointed as Associate Chief Administrative Judge (Legal). After graduating from law school, Judge Krause joined the U.S. Nuclear Regulatory Commission as a Panel law clerk. At the conclusion of her two-year term appointment, in 2009 she joined the agency’s Office of Commission Appellate Adjudication (OCAA), where she provided advice to the Commission on adjudicatory matters, including appeals from Atomic Safety and Licensing Board decisions. While working with OCAA, Judge Krause also performed rotational assignments in the Office of the General Counsel in the areas of rulemaking and legislation, and she served in the Office of the Commission as acting legal counsel for Commissioner Jeff Baran. In 2019, Judge Krause returned to the Panel in the role of Chief Counsel, providing advice to Panel judges and supervising the Panel’s law clerks. 

Jeremy A. Mercer

B.A., Youngstown State University
J.D., Ohio State University

Judge Mercer was appointed to the Panel as a full-time legal judge in December 2023.  After graduating law school, Judge Mercer clerked for a United States Magistrate Judge in Cleveland, Ohio, for two years.  His subsequent private practice in Pittsburgh, Pennsylvania, included his work as a litigation partner for several national and international law firms, including K&L Gates, LLP; Norton Rose Fulbright US, LLP; and Nelson Mullins Riley & Scarborough, LLP.  In that private practice, Judge Mercer focused on energy litigation, primarily in the oil and gas field.  As a litigator, Judge Mercer routinely defended clients in state and federal courts, at the trial and appellate levels, including serving as trial counsel for numerous jury and non-jury trials.  He also represented energy clients in administrative matters at the state and local levels. 

Alice C. Mignerey

B.S. University of Rochester
M.S. University of Rochester 
Ph.D. University of Rochester

Dr. Mignerey was appointed to the Panel as a part-time technical judge in 2006. As a professor of Chemistry at the University of Maryland since 1979, Dr. Mignerey specializes in Nuclear Chemistry, with research programs in basic nuclear reactions and the applications of nuclear analytical techniques to environmental problems. She has studied the dating and characterization of ground waters in Southern Maryland using accelerator mass spectrometry. Through her research on nuclear reactions, she has participated in experimental programs at many of the national laboratories, most recently the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Dr. Mignerey has served as the Chair of the Division of Nuclear Chemistry and Technology of the American Chemical Society and as a member of the Executive Committee of the Division of Nuclear Physics of the American Physical Society. Dr. Mignerey spent three years as a part-time program officer for Nuclear Physics in the Physics Division of the National Science Foundation. She has also served as a member of the Nuclear Science Advisory Committee, which provides guidance to the National Science Foundation and the Department of Energy on matters relating to Nuclear Science research.

Arielle J. Miller

B.A., Physics, Northwestern University
M.S., Nuclear Engineering, NC State University
Ph.D., Engineering, Howard University

Dr. Arielle Miller is a registered Professional Engineer (Maryland, Virginia, and District of Columbia) with expertise in nuclear and mechanical engineering who was appointed to the Panel as a full-time technical judge in 2024.  Dr. Miller began her career as a Surface Warfare Officer (USS Normandy) and as a Nuclear Propulsion Plant Watch Officer (USS Enterprise) during her five years in the U.S. Navy.  Her subsequent experience includes positions at GE Hitachi (sodium-cooled fast reactor design), Areva (nuclear services and Eagle Rock Enrichment Facility), the Office of Naval Research, and the Defense Nuclear Facilities Safety Board (nuclear criticality safety lead).  Dr. Miller’s extensive experience in engineering and leadership positions, including nuclear power and materials, led to her most recent work as a consultant involving nuclear plant operations, licensing, and safety inspections. She also assisted individuals and organizations in developing programs to increase women in STEM, especially women of color.  She has several scientific publications about nuclear effects on materials, sodium-cooled fast reactor licensing, and nuclear criticality.

Sekazi Mtingwa

B.S., Physics, Massachusetts Institute of Technology
B.S., Mathematics, Massachusetts Institute of Technology
M.A., Ph.D., Physics, Princeton University

Dr. Mtingwa was appointed to the Panel as a part-time technical judge in 2016. His areas of research include nuclear, accelerator and high energy physics, as well as nuclear energy policy. He is a principal partner at Triangle Science, Education & Economic Development, LLC, in Hillsborough, North Carolina. He consults on issues related to science, engineering and education and organizes workshops to introduce university faculty and students to the big user facilities at the national laboratories. He retired as Professor of Physics at North Carolina A&T State University, where he served as department chair. After leaving North Carolina A&T in 2001, he served as visiting professor of physics at both MIT and Harvard University, subsequently returning to MIT in 2006 and serving as senior lecturer until his retirement in 2012. Dr. Mtingwa assists institutions throughout Africa in building laser laboratories. He was a member of the DOE Nuclear Energy Research Advisory Committee during 1998-2008 and currently serves on its Fuel Cycle R&D Subcommittee. For his role in revitalizing federal funding to university nuclear science and engineering programs, Dr. Mtingwa received the Distinguished Service Award from the American Nuclear Society in 2015. Most recently, he received the 2017 Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators from the American Physical Society.

Steven P. Nesbit

B.S., Nuclear Engineering, University of Virginia
M.S., Nuclear Engineering, University of Virginia

Judge Nesbit was appointed to the Panel as a part-time technical judge in 2026. He has over forty-five years of experience in the nuclear field involving research reactors, commercial nuclear power reactors, used fuel management, and nonproliferation. He performed and managed safety analyses, core analyses, and fuel mechanical analyses for nuclear power reactors. He also worked on Department of Energy projects, including the New Production Reactor, the Yucca Mountain geologic repository, and surplus weapons plutonium disposition using mixed oxide fuel. Since forming LMNT Consulting he led or contributed to several projects to enhance the NRC regulatory framework for advanced reactors. During his career Judge Nesbit also worked on nuclear policy issues and twice testified to Congress on spent nuclear fuel management. He taught nuclear engineering as an adjunct faculty member at the University of North Carolina - Charlotte. Judge Nesbit has been a registered Professional Engineer since 1986. He served as President of the American Nuclear Society from 2021-2022 and is a Fellow of that society.

William W. Sager

B.S., Duke University
M.S., University of Hawaii 
Ph.D., University of Hawaii 

Dr. Sager was appointed to the Panel as a part-time technical judge in 2006. He has been an academic researcher and professor since 1983. From 1983-2012, he was professor in the Department of Oceanography at Texas A&M University.  Since 2013, he is professor in the Department of Earth and Atmospheric Sciences at the University of Houston.  His areas of research specialty include oceanography, marine geology, and earth sciences. He has authored and co-authored over 200 research articles, papers, and abstracts and has participated on 41 oceanographic research cruises.

David A. Smith

B.A., Mathematics/Education, Central Methodist University
M.S., Nuclear Engineering (Health Physics), University of Missouri
M.S., Nuclear Engineering Sciences (Medical Physics), University of Florida 
Ph.D., Environmental Sciences, Ohio State University 

Dr. Smith has an extensive background in health and medical physics, occupational and environmental health, and environmental sciences and engineering. He was appointed as an Administrative Judge (Technical) in 2024 and as Associate Chief Administrative Judge (Technical) in 2025. He has held prominent leadership and academic roles at institutions including Georgetown University, George Washington University, the National Intelligence University, and the Air Force Institute of Technology. A retired Air Force Lieutenant Colonel with over twenty-three years of service, Dr. Smith concluded his military career as Chief of the Radioisotope Committee Secretariat and Health Physics Consultant to the Air Force Surgeon General. He also served as Executive Director for the National Council on Radiation Protection and Measurements. Dr. Smith has co-authored numerous technical publications, presented at major conferences, and is a recipient of multiple military and civilian honors.

Paul J. Tikalsky

B.S., Civil and Environmental Engineering, University of Wisconsin – Madison
M.S., Civil Engineering, University of Texas - Austin
Ph.D., Civil Engineering, University of Texas - Austin

Dr. Tikalsky was appointed as a part-time technical judge in 2026. He is the former Dean and a Regents Service Professor of the College of Engineering, Architecture, and Technology at Oklahoma State University. Dr. Tikalsky previously served as the Chair of the Department of Civil and Environmental (and Nuclear) Engineering at the University of Utah and Professor of Civil and Environmental Engineering at Penn State University. His research and consulting expertise focuses on the integration of material science and technology for sustainable building materials, durability and sustainable structural systems, including industrial byproduct utilization, low-level radioactive slag, specialized concrete construction, and simulation-based reliability assessment. Dr. Tikalsky is a Fulbright Scholar. He has authored numerous articles on the durability of construction materials in severe environments, designing for diffusion and thermal storage in concrete, and the use of pozzolans in low carbon concrete. He has held leadership positions on technical and board committees with the American Concrete Institute, American Society of Engineering Education, and the Transportation Research Board. Dr. Tikalsky is a licensed professional engineer in four states and a foreign member of the Czech National Academy of Engineering.

Nicholas G. Trikouros

B.S., Fordham University 
M.S., New York University 
Eng., Polytechnic University

Judge Trikouros was appointed to the Panel as a full-time technical member in January 2006, after having served as a part-time technical judge in 2005. Judge Trikouros has over thirty years' experience in the nuclear industry, including as President/Founder of Panlyon Technologies, a professional consulting company involved in nuclear plant design, licensing, and safety analysis, and as the Manager of Safety and Risk Analysis and in senior engineering positions with GPU Nuclear Corporation. His areas of expertise include nuclear plant design basis and licensing, reactor systems, emergency operating procedures, transient and accident analyses, containment performance, plant operations engineering, and probabilistic risk assessment. Judge Trikouros provided onsite technical support during the Three Mile Island, Unit 2 accident and participated extensively in the post-accident evaluation effort. Judge Trikouros has served as an adjunct professor at Rutgers University providing graduate instruction on nuclear energy technology as well as on a variety of nuclear industry groups and committees, including a number of Electric Power Research Institute (EPRI) Advisory Groups, the NRC/Industry Technical Advisory Group for once-through steam generator testing, and the EPRI Utility Steering Committee's Analysis and Testing Subcommittee for Advanced Reactors. He is the author of numerous technical articles on transient analysis and reactor safety and worked as a consultant to the Department of Energy's International Nuclear Safety Program in Ukraine.

James M. Welch

B.S., Biology, William & Mary
M.S., Marine Biology and Biochemistry, University of Delaware
Ph.D., Zoology, Duke University

Dr. Welch was appointed to the Panel as a part time technical judge in 2026. He has been a professor and academic researcher since 1999. He teaches courses in oceanography, marine biology and physiology at Wittenberg University, where he was Chair of the Department of Biology from 2008-2022. Dr. Welch is a larval ecologist who studies the processes by which crab larvae move upstream in estuaries to reach and select settlement sites. His expertise spans physical oceanography, physiology, animal behavior, and natural history. Dr. Welch has authored and coauthored over 20 research articles and 75 meeting presentations/abstracts, most with undergraduate coauthors, and has participated on 6 oceanographic research cruises.

Stefan R. Wolfe

B.S., United States Military Academy (West Point)
J.D., Rutgers Law School

Judge Wolfe joined the Panel as a full-time legal member in July 2025.  After graduating from West Point in 1996, he began his military service as a helicopter pilot and platoon leader for an armed air reconnaissance cavalry unit with service in Germany and Kosovo.  Graduating summa cum laude from Rutgers Law School in 2004, he continued to serve in the Army as a prosecutor, trial judge, and as an appellate judge on the Army Court of Criminal Appeals.  After departing the Army in 2019, Judge Wolfe served as the General Counsel for the National Commission on Military Aviation Safety, and as an attorney for the Department of Justice Tax Division.