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.
Division Spotlight
Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
Meeting Spotlight
2025 ANS Annual Conference
June 15–18, 2025
Chicago, IL|Chicago Marriott Downtown
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
Jun 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
July 2025
Nuclear Technology
June 2025
Fusion Science and Technology
Latest News
Findings of the ANS Executive Order Expert Advisory Group
On May 23, President Donald Trump signed four Executive Orders (EOs) designed to “usher in a nuclear energy renaissance” by building on federal policies and programs and directing efficiencies in the licensing, siting, development, and deployment of advanced reactor technologies.
In order to evaluate the specific proposals contained in the EOs, a group of experts was convened from various sectors of the U.S. nuclear technology enterprise, under the auspices of the ANS External Affairs Committee, to compare the EOs against existing ANS board-approved Position Statements and to offer constructive input for subsequent implementation by the Trump administration.
The group’s findings and feedback, which were delivered by ANS CEO Craig Piercy to ANS President Lisa Marshall and the Board of Directors, are listed below, grouped by individual EO.
Rob P. Rechard, Lawrence C. Sanchez, Holly R. Trellue
Nuclear Technology | Volume 144 | Number 2 | November 2003 | Pages 222-251
Technical Paper | Radioactive Waste Management and Disposal | doi.org/10.13182/NT03-5
Articles are hosted by Taylor and Francis Online.
This article presents several reasonable cases in which four mechanisms - dissolution, physical mixing, adsorption, and precipitation (either chemical change or evaporation) - might concentrate fissile material in and around a disposal container for radioactive waste at the proposed repository at Yucca Mountain, Nevada. The possible masses, concentrations, and volume are then compared to criticality limits. The cases examined evaluate the geologic barrier role in preventing criticality since engineered options for preventing criticality (e.g., boron or gadolinium neutron absorber in the disposal container) are not considered. The solid concentrations able to form in the natural environment are insufficient for criticality to occur because (a) solutions of 235U and 239Pu are clearly not critical; (b) physical mixing of fissile material with the entire potential iron oxide (as goethite - FeOOH) in a waste package is not critical; (c) the adsorption of 239Pu on consolidated iron oxide in a waste package is not critical; (d) the adsorption of 235U on consolidated iron oxide in a waste package is not critical when accounting for reduced adsorption because of carbonates at high pH; (e) the filtration of iron oxide colloids, containing fissile material, by the thin invert material is not critical; (f) insufficient retention through precipitation of 235U or 239Pu occurs in the invert; (g) adsorption of 235U and 239Pu on devitrified or clinoptolite-rich tuff below the repository is not critical; (h) the average precipitation/adsorption of 235U as uranyl silicates in the tuff is not critical by analogy with calcite deposition in lithophysae at Yucca Mountain; and (i) precipitation/adsorption (caused by cyclic drying) as uranyl silicates on fracture surfaces of the tuff is not critical by analogy with the oxidation of UO2, migration of UVI, and precipitation in fractures at the Nopal I ore deposit in Mexico.
