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.
Explore membership for yourself or for your organization.
Conference Spotlight
2026 ANS Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
Latest Magazine Issues
Feb 2026
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
March 2026
Nuclear Technology
February 2026
Fusion Science and Technology
January 2026
Latest News
Hanford begins removing waste from 24th single-shell tank
The Department of Energy’s Office of Environmental Management said crews at the Hanford Site near Richland, Wash., have started retrieving radioactive waste from Tank A-106, a 1-million-gallon underground storage tank built in the 1950s.
Tank A-106 will be the 24th single-shell tank that crews have cleaned out at Hanford, which is home to 177 underground waste storage tanks: 149 single-shell tanks and 28 double-shell tanks. Ranging from 55,000 gallons to more than 1 million gallons in capacity, the tanks hold around 56 million gallons of chemical and radioactive waste resulting from plutonium production at the site.
Roberto Ponciroli, Stefano Passerini, Richard B. Vilim
Nuclear Technology | Volume 199 | Number 1 | July 2017 | Pages 16-34
Technical Paper | doi.org/10.1080/00295450.2017.1326783
Articles are hosted by Taylor and Francis Online.
Advanced reactors are often claimed to be passively safe against unprotected upset events. In common practice, these events are not considered in the context of the plant control system, i.e., the reactor is subjected to classes of unprotected upset events while the normally programmed response of the control system is assumed not to be present. However, this approach constitutes an oversimplification since, depending on the upset involving the control system, an actuator does not necessarily go in the same direction as needed for safety. In this work, dynamic simulations are performed to assess the degree to which the inherent self-regulating plant response is safe from active control system override. The simulations are meant to characterize the resilience of the plant to unprotected initiators. The initiators were represented and modeled as an actuator going to a hard limit. Consideration of failure is further limited to individual controllers as there is no cross-connect of signals between these controllers. The potential for passive safety override by the control system is then relegated to the single-input single-output controllers. The results show that when the plant control system is designed by taking into account and quantifying the impact of the plant control system on accidental scenarios there is very limited opportunity for the preprogrammed response of the control system to override passive safety protection in the event of an unprotected initiator.