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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
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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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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.”
Kostadin A. Dinov, Kazuo Kasahara
Nuclear Technology | Volume 115 | Number 1 | July 1996 | Pages 81-90
Technical Paper | Material | doi.org/10.13182/NT96-A35277
Articles are hosted by Taylor and Francis Online.
A theoretical approach is discussed that regards the kinetically determined pressurized water reactor (PWR) primary system as a set of thermodynamically defined metastable states that the related high-temperature aqueous system containing a combination of possible oxide phases (NixFe3−xO4, Fe3O4, and metallic nickel or NiO) and corresponding dissolution products may undergo under specified initial conditions. The study shows that stability zones of those metastable states, particularly M1 (NixFe3−xO4) and M3 [Ni(m) + NixFe3−xO4], cover practically the entire PWR operational range and depend on specific plant conditions and applied chemistry control. The thermodynamic analysis is predicated on the belief that defining the stability transition boundary between those states — found as a function of temperature, coolant pH, dissolved hydrogen (DH), and ferrite stoichiometry (x value) — is of primary importance for corrosion product behavior. Such a stability change influences both the particulate and ionic levels and the related activity transport and should be regarded as an important factor in optimizing PWR primary chemistry. The study offers an original approach to reassessing such important issues as thermodynamic data and the solubility of spinel oxides, the role of transport of particulates and soluble species, “optimum” pH and DH, and the chemistry effect on crud burst.