Matthew Denman: On Probabilistic Risk Assessment

September 24, 2021, 3:32PMNuclear News

Matthew Denman

Probabilistic risk assessment is a systematic methodology for evaluating risks associated with a complex engineered technology such as nuclear energy. PRA risk is defined in terms of possible detrimental outcomes of an activity or action, and as such, risk is characterized by three quantities: what can go wrong, the likelihood of the problem, and the resulting consequences of the problem.

Matthew Denman is principal engineer for reliability engineering at Kairos Power and the chair of the American Nuclear Society and American Society of Mechanical Engineers Joint Committee on Nuclear Risk Management’s Subcommittee of Standards Development. As a college student at the University of Florida, Denman took a course on PRA but didn’t enjoy it, because he did not see its connection to the nuclear power industry. Later, during his Ph.D. study at the Massachusetts Institute of Technology, his advisor was Neil Todreas, a well-known thermal hydraulics expert. Todreas was working on a project with George Apostolakis, who would leave MIT to become a commissioner of the Nuclear Regulatory Commission. The project, “Risk Informing the Design of the Sodium-Cooled Fast Reactor,” was a multi-university effort funded through a Department of Energy Nuclear Energy Research Initiative (NERI) grant. Todreas and Apostolakis were joined in this project by a who’s who of nuclear academia, including Andy Kadak (MIT, ANS past president [1999–2000]), Mike Driscoll (MIT), Mike Golay (MIT), Mike Lineberry (Idaho State University, former ANS treasurer), Rich Denning (Ohio State University), and Tunc Aldemir (Ohio State University).

Helping to solve the plant safety puzzle: An overview of PRA

September 17, 2021, 3:01PMNuclear NewsCurtis Smith, Andrew Miller, Stephen Hess, and Fernando Ferrante

Probabilistic risk assessments (PRAs) have advanced the safe operation of the U.S. reactor fleet over many decades. Risk insights from PRAs have provided information from many different perspectives, from what is most important to maintain at a facility to a better understanding of how to address new information regarding safety issues. The methods and tools that have supported the creation and enhancement of PRA models were established through multiple decades of research, starting with WASH-1400, The Reactor Safety Study,1 published in 1975, through the comprehensive plant-specific models in use today.

Ratliff and Harris: Innovation for safety and reliability

October 23, 2020, 3:14PMNuclear NewsSusan Gallier

Ratliff

Harris

When Floyd Harris began working at Duke Energy’s Brunswick nuclear plant about 24 years ago as a radiation protection technician, robotics and remote monitoring were considered tools for radiation protection and nothing more. Now, teams from across the site, including engineering, maintenance, and operations, rely on the system of robots and cameras Harris is responsible for. “If you want to put those technologies under one umbrella,” says Harris, who now holds the title of nuclear station scientist, “it would be monitoring plant conditions.”

That monitoring is critical to effective plant maintenance. As Plant Manager Jay Ratliff explains, the goal is to “find a problem before it finds us” and ensure safety and reliability. Nuclear News Staff Writer Susan Gallier talked with Ratliff and Harris about how robotics and remote systems are deployed to meet those goals.

At Brunswick, which hosts GE-designed boiling water reactors in Southport, N.C., ingenuity and hard work have produced a novel remote dosimetry turnstile to control access to high-radiation areas, an extensive network to handle data from monitoring cameras, rapid fleetwide access to camera feeds to support collaboration, and new applications for robots and drones.