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Division Spotlight
Fuel Cycle & Waste Management
Devoted to all aspects of the nuclear fuel cycle including waste management, worldwide. Division specific areas of interest and involvement include uranium conversion and enrichment; fuel fabrication, management (in-core and ex-core) and recycle; transportation; safeguards; high-level, low-level and mixed waste management and disposal; public policy and program management; decontamination and decommissioning environmental restoration; and excess weapons materials disposition.
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.”
Hiroshi Okuno, Tomohiro Sakai
Nuclear Technology | Volume 122 | Number 3 | June 1998 | Pages 265-275
Technical Paper | Reactor Safety | doi.org/10.13182/NT98-A2868
Articles are hosted by Taylor and Francis Online.
It is well known that the maximum reactivity is realized for the flat fuel distribution with the fuel importance function being constant. The Lagrange method of an undetermined multiplier was used to incorporate the constraint that the mean uranium concentration or the total uranium mass shall be conserved. The OPT-SN computer program is developed, which includes an SN code ANISN-JR to solve the multigroup neutron transport equations. This program has given more reliable results than the previous scheme using the diffusion approximation, especially for bare and partially reflected fuel systems. OPT-SN was applied to criticality calculations for mixtures of 5 wt% 235U-enriched uranium dioxide and water (slurries) covered with a water reflector in all directions, in half directions, and uncovered. The calculations made for the UO2-H2O slurries in a sphere, an infinitely long cylinder, and an infinite slab with a water reflector in all directions revealed that a degree of nonuniformity effect tends to increase as the mean uranium concentration increases. It amounts to ~6% k/k for these systems at the mean uranium concentration of 4000 gU/l. The degree of nonuniformity effect is found more than 6% k/k even for as low a mean uranium concentration as 700 gU/l of the slab fuel system with a reflector only on one side. This fact confirmed from the viewpoint of nuclear criticality safety the importance of evaluating the optimum distribution of fuel in slurry contained in a tank placed on the concrete floor. Precipitation is regarded as a realistic example.
