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 Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
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
Dec 2025
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
January 2026
Nuclear Technology
December 2025
Fusion Science and Technology
November 2025
Latest News
Fusion office bill introduced in line with DOE reorganization plan
Cornyn
Padilla
Sens. Alex Padilla (D., Calif.) and John Cornyn (R., Texas) have introduced bipartisan legislation to formally establish the Office of Fusion at the Department of Energy. This move seeks to codify one of the many changes put forward by the recent internal reorganization plan for offices at the DOE.
Companion legislation has been introduced in the House of Representatives by Reps. Don Beyer (D., Va.) and Jay Obernolte (R., Calif.), who are cochairs of the House Fusion Energy Caucus.
Details: According to Obernolte, “Congress must provide clear direction and a coordinated federal strategy to move fusion from the lab to the grid, and this legislation does exactly that.”
Joonhong Ahn, Atsuyuki Suzuki
Nuclear Technology | Volume 101 | Number 1 | January 1993 | Pages 79-91
Technical Paper | Waste Management Special / Radioactive Waste Disposal | doi.org/10.13182/NT93-A34769
Articles are hosted by Taylor and Francis Online.
A mathematical analysis of the diffusion of the 241Am → 237Np decay chain in the artificial barrier of a high-level radioactive waste repository is presented. First, analytical solutions obtained are for the space- and time-dependent concentration of 241 Am in the artificial barrier and the time-dependent amount of americium precipitated at the surface of the waste glass, based on the assumption of the congruency of the radionuclides with solubility-limited dissolution of the glass matrix. The effects of solubility sharing with coexisting 243Am are considered. Transport and precipitation of 237Np in the artificial barrier are analyzed by dividing the time domain into a small time domain, where the 241Am concentration is so large that 237Np precipitation is dominant, and a large time domain, where the 241Am becomes negligible and the precipitation region shrinks by diffusion from the precipitation front. The equation for the movement of the precipitation front is obtained. As the overpack lifetime increases, the effect of neptunium precipitation becomes less significant. With a lifetime longer than ∼6000 yr, an earlier model, where neptunium is treated as a mother nuclide and the precipitation occurs only at the glass surface, can be used. With the solubility for Np(OH)4, the effect of neptunium precipitation is as small as a factor of 2 in terms of the maximum mass release rate at the outer boundary of the artificial barrier, and the earlier model can be used for safety assessment. With the solubility for NpO2, the current model gives a maximum mass release rate at the outer boundary that is one order of magnitude greater than the previous one.
