ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
Utility Working Conference and Vendor Technology Expo
August 8–11, 2021
Marco Island, FL|JW Marriott Marco Island
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
Latest Magazine Issues
Latest Journal Issues
Nuclear Science and Engineering
Fusion Science and Technology
Metz on Harold Denton: Memories of a life in nuclear safety
A number of years ago, historian and writer Chuck Metz Jr. was at the Bush’s Visitor Center in Tennessee’s Great Smoky Mountains when he ran into former Nuclear Regulatory Commission official Harold Denton and his wife. Metz was at the visitor center, which opened in 2010 and is now a tourist hotspot, because, as he explained to the Dentons at the time, he had overseen the development of its on-site museum and had written a companion coffee-table history book.
The chance meeting turned into a friendship and a fruitful collaboration. Denton, who in 1979 was the public spokesperson for the NRC as the Three Mile Island-2 accident unfolded, had been working on his memoir, but he was stuck. He asked Metz for help with the organization and compilation of his notes. “I was about to retire,” Metz said, “but I thought that exploring the nuclear world might be an interesting change of pace.”
Denton passed away in 2017, but by then Metz had spent many hours with his fast friend and was able to complete the memoir, Three Mile Island and Beyond: Memories of a Life in Nuclear Safety, which was published recently by ANS. Metz shared some of his thoughts about Denton and the book with Nuclear News. The interview was conducted by NN’s David Strutz.
B. C. Johnson, G. E. Apostolakis, R. Denning
Nuclear Technology | Volume 172 | Number 2 | November 2010 | Pages 108-119
Technical Paper | Reactor Safety | dx.doi.org/10.13182/NT10-A10898
Articles are hosted by Taylor and Francis Online.
We consider the design of a sodium-cooled fast reactor (SFR) in the context of the risk-informed technology neutral framework (TNF) for licensing new reactors that has been proposed by the U.S. Nuclear Regulatory Commission staff. In lieu of design-basis accidents (DBAs), the TNF imposes limits on the frequency and consequences of accident sequences called licensing-basis events (LBEs). We present a method to define LBEs for a SFR using generic functional event trees. Very large consequence events are considered beyond the licensing basis in the TNF as long as their mean frequencies are less than 1 × 10-7 per reactor year.For SFRs, energetic accidents have historically represented a major regulatory hurdle in the traditional licensing system that is based on DBAs. As a result, key systems that prevent or mitigate these accidents may have been overdesigned. We propose a new importance measure, the Limit Exceedance Factor (LEF). It is the factor by which the failure probability of structures, systems, and components (SSCs) may be multiplied such that the frequency of a risk metric reaches a limit. LEF allows a designer to know how much margin exists to the safety limit for each SSC. Alternatively, in the case where a design does not meet the frequency limit, LEF can reveal which systems are candidates for improvement to satisfy the limit. Within the TNF, using a frequency limit of 1 × 10-7 per reactor year and LEF, we find that for some SSCs a wide margin exists to this limit. Therefore, these SSCs are candidates for simplification resulting in economic benefit. This simplification should be done under the frequency-consequence constraints and the deterministic defense-in-depth requirements described in the TNF.