Bradley T Rearden

Bradley T Rearden

Modeling and Simulation Integration Leader


Brad Rearden is the Modeling and Simulation Integration Lead for the Reactor and Nuclear Systems Division (RNSD) of Oak Ridge National Laboratory, the manager of the SCALE Code System, and the leader of the Integration Product Line for the U.S. DOE Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program. Brad is a results-driven, hands-on individual who champions innovation, communication, and quality as demonstrated through 18 years of nuclear engineering research and development, with successful management and team building leadership.

As leader of RNSD Modeling and Simulation Integration, coordinates and integrates signature capabilities in nuclear data; neutronics; radiation transport and shielding; thermal hydraulics; structural mechanics; fuel performance; reactor safety; system dynamics instrumentation, and controls; nuclear security; and used nuclear fuel; as well cross cutting capabilities including quality assurance, software development infrastructure, user interfaces, training, multiphysics coupling, verification, validation, and uncertainty quantification.

In this role, Brad is responsible for:
• Leading the RNSD Modeling and Simulation Leadership Team, a strategic cross-cutting team consisting of select line managers and senior staff from Consortium for the Advanced Simulations of LWRs (CASL), NEAMS, SCALE and other programs who guide technical, programmatic, and managerial aspects of modeling and simulation activities; and
• Performing strategic planning and taking actions to realize near-term and long-term objectives and goals.

SCALE is a nuclear modeling and simulation suite developed with the sponsorship of the U.S. Department of Energy, the National Nuclear Security Administration, and the U.S. Nuclear Regulatory Commission that provides validated and user-friendly tools for nuclear criticality safety, reactor physics, radiation shielding, radiation source term characterization, and sensitivity and uncertainty analysis. Since 1980 regulators, industry, and researchers have relied on SCALE for licensing and design calculations. SCALE is currently deployed to 8000 users in 56 nations.

As manager of the SCALE Code System, Brad is responsible for:
• Providing vision for computational capabilities and interfaces;
• Coordinating activities of nearly 50 advanced-degreed engineers, computer scientists and physicists and managing multi-million dollar budgets;
• Developing and implementing ISO 9001 quality assurance, configuration management, and deployment strategies and associated infrastructure;
• Leading modernization of legacy features and interfacing with multiple projects;
• Interfacing with sponsors and end users;
• Coordinating over 10 weeks of training courses per year, domestically and internationally;
• Providing technical presentations at domestic and international conferences;
• Coordinating end-user communication through website, newsletter, e-mail helpline, and social media.

As the leader of the NEAMS Integration Product Line, Brad provides technical guidance and vision for the NEAMS Program to develop, deploy and apply a state-of-the-art modeling and simulation toolkit on leadership class computing platforms for predictive evaluations of the performance and safety of advanced nuclear reactor and fuel designs. This work is completed under the auspices of the U.S. DOE, Office of Nuclear Energy. Responsibilities of this role include:
• Direct activities at five DOE national laboratories to integrate the capabilities of the Reactors Product Line and the Fuels Product Line into multiphysics and multiscale applications, integrate quality assurance and uncertainty quantification technologies, and integrate the user with the simulation and solution;
• Coordinate NEAMS funded projects under the Nuclear Energy University Program (NEUP) and Small Business Innovation Research (SBIR);
• Serve as a member of the NEAMS Leadership Council supporting the National Technical Director and coordinating activities across the program.

Prior to assuming the management of SCALE in 2009 and NEAMS leadership role in 2015, Brad created, deployed, and promoted the world’s first production-quality sensitivity and uncertainty analysis tools for nuclear criticality safety and reactor physics, which are especially applied for code validation and experiment design.

Brad received his B.S., M.S., and Ph.D. in Nuclear Engineering at Texas A&M University (1993, 1995, 1999).


  • American Nuclear Society - Landis Young Member Engineering Achievement Award - 2007
  • U.S. Department of Energy – Undergraduate Research Programs – Outstanding Mentor Award, 2004 and 2007.
  • Oak Ridge Institute for Science and Education – Outstanding Mentor Award, 2007.
  • ORNL Nuclear Science and Technology Division – Scientific and Technical Awards for Release of SCALE 5 and Development of Sensitivity and Uncertainty Analysis Methods – 2004
  • UT-Battelle Awards Night – Outstanding Accomplishment in Science and Technology – Early Career Award for Engineering Accomplishment – Finalist 2003
  • Apple Computer – Worlds of Science K–12 Educational Software Contest – 1st Place Adult Individual Category – 1998
  • Institute for Nuclear Power Operations – Graduate Fellowship Recipient - 1993-1994