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
Aerospace Nuclear Science & Technology
Organized to promote the advancement of knowledge in the use of nuclear science and technologies in the aerospace application. Specialized nuclear-based technologies and applications are needed to advance the state-of-the-art in aerospace design, engineering and operations to explore planetary bodies in our solar system and beyond, plus enhance the safety of air travel, especially high speed air travel. Areas of interest will include but are not limited to the creation of nuclear-based power and propulsion systems, multifunctional materials to protect humans and electronic components from atmospheric, space, and nuclear power system radiation, human factor strategies for the safety and reliable operation of nuclear power and propulsion plants by non-specialized personnel and more.
Meeting Spotlight
Conference on Nuclear Training and Education: A Biennial International Forum (CONTE 2025)
February 3–6, 2025
Amelia Island, FL|Omni Amelia Island Resort
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
Jan 2025
Jul 2024
Latest Journal Issues
Nuclear Science and Engineering
February 2025
Nuclear Technology
Fusion Science and Technology
Latest News
A series of firsts delivers new Plant Vogtle units
Southern Nuclear was first when no one wanted to be.
The nuclear subsidiary of the century-old utility Southern Company, based in Atlanta, Ga., joined a pack of nuclear companies in the early 2000s—during what was then dubbed a “nuclear renaissance”—bullish on plans for new large nuclear facilities and adding thousands of new carbon-free megawatts to the grid.
In 2008, Southern Nuclear applied for a combined construction and operating license (COL), positioning the company to receive the first such license from the U.S. Nuclear Regulatory Commission in 2012. Also in 2008, Southern became the first U.S. company to sign an engineering, procurement, and construction contract for a Generation III+ reactor. Southern chose Westinghouse’s AP1000 pressurized water reactor, which was certified by the NRC in December 2011.
Fast forward a dozen years—which saw dozens of setbacks and hundreds of successes—and Southern Nuclear and its stakeholders celebrated the completion of Vogtle Units 3 and 4: the first new commercial nuclear power construction project completed in the U.S. in more than 30 years.
R. L. Crowther, J. W. Weil
Nuclear Science and Engineering | Volume 3 | Number 6 | June 1958 | Pages 747-757
Technical Paper | doi.org/10.13182/NSE58-A25508
Articles are hosted by Taylor and Francis Online.
The presence of a large, sharp resonance at 1 ev in Pu240 results in the effective pile cross section for this isotope being very much larger than the true thermal cross section. Furthermore, the narrowness of this resonance causes the absorption of epithermal neutrons in Pu240 to be strongly self-shielded. Consequently, the effective cross section of Pu240 will be a function of reactor spectrum and of the Pu240 concentration at any given time. The significance of this effect can be appreciated by noting that the effective cross section of this isotope is frequently more than twice the effective thermal value. An approximate method of calculation has been applied to long term reactivity problems. The importance of the resonance augmentation and concentration dependence of the Pu240 cross section is particularly evident in the first few thousand Mwd/t and causes significant changes in the reactivity required to reach any longer burnout. Sample calculations are presented and comparisons with the Canadian experimental determinations of the effective Pu240 cross section are made. An effective constant Pu240 cross section is presented which will yield approximately correct burnout results when used in conventional irradiation studies.
