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
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
Standards Program
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
Sep 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
September 2025
Nuclear Technology
Fusion Science and Technology
August 2025
Latest News
Aalo breaks ground in Idaho
Eight days after Aalo Atomics released the details of its securing of $100 million in Series B funding, the company announced that it has broken ground on the 50-MWe Aalo-X. Sited in the desert beside Idaho National Laboratory, it will be the company’s first nuclear power plant, and it remains on track to go on line by July 4, 2026.
Reuben Rainisch, Victor R. Fricke
Nuclear Technology | Volume 87 | Number 2 | October 1989 | Pages 478-485
Technical Paper | TMI-2: Health Physics and Environmental Release / Nuclear Safety | doi.org/10.13182/NT89-A27740
Articles are hosted by Taylor and Francis Online.
During the accident at Three Mile Island Unit 2, a significant mass of core debris relocated to the bottom head of the reactor vessel. Subsequently, defueling activities in the core area redistributed the fuel and caused further core debris to relocate to the lower head region. An analytical approach is presented for determining the relative increase in lower plenum debris bed mass from observed changes in ex-core neutron detector readings. The neutron source magnitude of the fuel in the lower reactor vessel plenum and the degree of subcritical multiplication of neutrons in the lower head are investigated. Based on the mathematical relation formulated, it is estimated that during lower core area defueling (September 1986 to November 1987), between 12 and 23.5 additional tonnes of core materials relocated to the lower head.