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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
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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2024: The Year in Nuclear—July through September
Another calendar year has passed. Before heading too far into 2025, let’s look back at what happened in 2024 in the nuclear community. In today's post, compiled from Nuclear News and Nuclear Newswire are what we feel are the top nuclear news stories from July through September 2024.
Stay tuned for the top stories from the rest of the past year.
J. T. Mihalczo, W. T. King
Nuclear Technology | Volume 84 | Number 2 | February 1989 | Pages 205-223
Technical Paper | Techniques | doi.org/10.13182/NT88-2
Articles are hosted by Taylor and Francis Online.
The method used since 1970 for determining the subcriticality of High-Flux Isotope Reactor (HFIR) fuel elements submerged in water is to add extra reactivity-calibrated uranium fuel plates and neutron absorber strips to a fuel element in order to achieve delayed criticality when it is submerged in water. This quality assurance (QA) verification determines that a fuel element meets reactivity specifications before it is used in the reactor. The use of the 252Cf-source-driven neutron noise analysis method to measure the subcriticality of fuel elements as an alternate to the critical experiment method was investigated by performing experiments with 29 HFIR fuel elements submerged in water. Reactivity was also measured by the break frequency noise analysis method. These measurements have shown that the 252Cf-source-driven noise analysis method can be used to determine whether HFIR fuel elements are fabricated within design specification by measuring the subcritical neutron multiplication factor of the fuel element submerged in water without the need to achieve delayed criticality. These subcritical measurements can replace the existing critical experiments for QA testing of fuel elements before use in a reactor and would be a more accurate and cost-effective method with reduced personnel radiation exposure and increased nuclear criticality safety. In addition, these experiments have shown that (a) measurements can be made with the detectors outside the water reflector tank; (b) the results do not depend on the type of detector used (neutron sensitive, gammaray sensitive, or sensitive to both neutrons and gamma rays); and (c) the method can measure the reactivity of the fuel element partially submerged and has the sensitivity to determine the effects of small uranium mass changes (∼1%) in the fuel element while the element is partially flooded (approximately half submerged) and very far subcritical. Validation of this method on these fuel elements suggests a potential for broad application of the 252Cf-source-driven noise analysis for QA testing of water reactor fuel elements where it is possible to submerge the elements in water without achieving a delayed critical state.
