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Division Spotlight
Reactor Physics
The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
Meeting Spotlight
Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
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
Vogtle-3 shuts down for valve issue
One of the new Vogtle units in Georgia was shut down unexpectedly on Monday last week for a valve issue that has since been investigated and repaired. According to multiple local news outlets, Georgia Power reported on July 17 that Unit 3 was back in service.
Southern Company spokesperson Jacob Hawkins confirmed that Vogtle-3 went off line at 9:25 p.m. local time on July 8 “due to lowering water levels in the steam generators caused by a valve issue on one of the three main feedwater pumps.”
Tsuyoshi Okawa, Ehud Greenspan
Nuclear Technology | Volume 160 | Number 3 | December 2007 | Pages 257-278
Technical Paper | Fission Reactors | doi.org/10.13182/NT07-A3898
Articles are hosted by Taylor and Francis Online.
The Encapsulated Nuclear Heat Source (ENHS) is a small lead-bismuth-cooled Generation IV reactor designed to have a once-for-life core with a nearly zero burnup reactivity swing and heat removal by natural circulation. All the ENHS cores designed so far have positive coolant void reactivity. This work searches for ENHS core designs having negative coolant void reactivity feedback and quantifies the penalty associated with a design for negative void reactivity. The approaches tried for turning the positive void coefficient negative are as follows: (a) enhancing the neutron leakage probability by reducing the fuel length, introducing neutron absorbers at the core boundary, using a gas-lift pump to introduce gas bubbles throughout the coolant in the core and fission gas plenum regions, and incorporating neutron-streaming channels in and adjacent to the core; (b) introducing into the core materials, such as Ca3N2, having enhanced absorption cross section at high energy; and (c) introducing into the core materials, such as CaH2, that will keep the neutron spectrum softer in the case of coolant voiding.The preferred negative void reactivity core design consists of 100-cm-long fuel rods, a 20-cm-thick B4C layer below the core, and a voided channel around the core radial boundary. The reactivity effect is negative when the coolant is voided from the entire core and even from only the central region of the core. In order to maintain a nearly zero burnup reactivity swing over at least 20 effective full-power years (EFPY), the core pitch-to-diameter ratio (P/D) has to be reduced from the reference value of 1.36 to 1.20. Correspondingly, for a given ENHS module dimensions the power level that can be removed by natural circulation from this core is ~75% of the reference core. Allowing a burnup reactivity swing of ~0.1% over 20 EFPY enables attaining a negative void reactivity core having P/D of 1.27 that can deliver ~93% of the P/D = 1.36 core power.