ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
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Division Spotlight
Education, Training & Workforce Development
The Education, Training & Workforce Development Division provides communication among the academic, industrial, and governmental communities through the exchange of views and information on matters related to education, training and workforce development in nuclear and radiological science, engineering, and technology. Industry leaders, education and training professionals, and interested students work together through Society-sponsored meetings and publications, to enrich their professional development, to educate the general public, and to advance nuclear and radiological science and engineering.
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!
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Latest News
Terrestrial Energy looks at EnergySolutions-owned sites for IMSR plants
Advanced reactor developer Terrestrial Energy and Utah-based waste management company EnergySolutions announced they have signed a memorandum of understanding to collaborate on the siting and deployment of Terrestrial Energy’s integral molten salt reactor plants at EnergySolutions-owned sites.
D. F. Hollenbach
Nuclear Science and Engineering | Volume 179 | Number 3 | March 2015 | Pages 342-351
Technical Note | doi.org/10.13182/NSE13-46
Articles are hosted by Taylor and Francis Online.
More than 50 years ago it was postulated that a naturally occurring nuclear reactor was possible if it started 2 billion years ago. The subsequent discovery of the natural reactor at Oklo confirmed that it is possible for a nuclear fission reactor to naturally form and cycle on and off over extended periods of time. The hypothesis of a naturally occurring reactor was extended to include the possibility of significant quantities of uranium aggregating inside the molten core of Earth due to gravity during its formation. When sufficient quantities of uranium accumulate, a self-sustaining fission reactor could form, which would fluctuate in power as uranium fissions and fission products are produced. Lighter elements would migrate out of the reactor region, and heavier elements would coalesce due to gravity. In this technical note, SCALE, a state-of-the-art nuclear engineering computer code system developed at Oak Ridge National Laboratory, was used to investigate this hypothesis. The analysis indicates that the overall operational parameters of a postulated nuclear fission reactor located in the inner core of Earth must fall within a relatively narrow band in order to still be operating today. If the overall power level were too low, the reactor would not breed sufficient fissile material, and the average enrichment would drop below the level required to form a self-sustained fast reactor. If the power level were too high, the reactor would have burned itself out well before the present day. The objective of this technical note is to provide calculations that support an existing geo-reactor and the operating parameters that would govern a deep-Earth reactor and allow it to still be operating today, 4.5 billion years after Earth was formed. To help bound the possible power range, a simplified, one-dimensional, homogeneous, deep-Earth reactor having a steady-state fission power is simulated over geologic time. Power levels and start times are varied. The simulations show that if the reactor were still operating today, it would have an overall lifetime average operating fission power of <3 TW. Analyses show that both instantaneous and cumulative 3He/4He ratios are a function of fission power, 235U/238U ratio, total uranium mass, and geo-reactor starting time. The calculated 3He/4He ratios are consistent with those observed in nature.