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Division Spotlight
Materials Science & Technology
The objectives of MSTD are: promote the advancement of materials science in Nuclear Science Technology; support the multidisciplines which constitute it; encourage research by providing a forum for the presentation, exchange, and documentation of relevant information; promote the interaction and communication among its members; and recognize and reward its members for significant contributions to the field of materials science in nuclear technology.
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.”
Seokho H. Kim, George F. Flanagan
Nuclear Technology | Volume 166 | Number 3 | June 2009 | Pages 230-239
Technical Paper | 2007 Space Nuclear Conference / Reactor Safety | doi.org/10.13182/NT09-A8837
Articles are hosted by Taylor and Francis Online.
A hydrodynamics model has been developed to study extreme deformation of the space reactor system impacting on the ground with a high velocity. Two-dimensional geometry models for a monolithic core and a pinned core reactor have been developed with dynamic material models, including the material constitutive models and the equation-of-state models. Calculations have been performed for the reactor impacting onto dry sand at 230 and 150 m/s. A pinned core has a much larger fraction of gas volume in the reactor core and thus collapses faster than a monolithic core. The 150 m/s impact velocity case reveals that the gas coolant channels survive in a monolithic core even though the reactor is massively deformed. In a pinned core, however, most of the gas coolant region collapses with intact or partially collapsed fission product gas cores that are protected by solid UO2 fuel. The sand density varies as it is being compressed. Generally, sand beneath the impacting reactor has a higher density as it is compressed. In addition to consideration of global criticality, it is necessary to investigate local criticality. Because of nonuniform distribution of the gas coolant channels in a deformed monolithic core for the 230 m/s impact velocity case, it may be possible to induce criticality locally in those regions where collapse is more severe. It is not straightforward to make an engineering judgment based solely on impact analysis regarding which core concept is more susceptible to criticality events. The current impact study reveals that a pinned core reactor collapses faster than a monolithic core reactor. A reactor that collapses faster is thought to be more susceptible to producing a criticality. However, a monolithic core reactor with much higher mass and kinetic energy develops much higher compaction in the dry sand beneath the reactor. This means that it is expected to better reflect fast neutrons from the bottom boundary where the sand density for a monolithic core impact becomes much higher than for a pinned core impact. It is strongly recommended that neutronics calculations be performed to determine the susceptibility of criticality for the massively deformed nuclear reactors including appropriate reflecting boundary conditions.