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2024 ANS Annual Conference
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Why should safeguards by design be a global effort?
Jeremy Whitlock
I can’t think of a more exciting time to be working in nuclear, with the diversity of advanced reactor development and increasing global support for nuclear in sustainable energy planning. But we can’t lose sight of the need to plan for efficient international safeguards at the same time.
Global nuclear deployment has been underpinned since 1970 by the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), making it a key customer requirement for governments to demonstrate unequivocally that the technology is not being misused for weapons development.
The International Atomic Energy Agency (IAEA) has helped verify this commitment for more than 50 years, but it has never safeguarded many of the advanced reactors (and related fuel cycle processes) being developed today.
T. Ginsberg, D. M. France
Nuclear Science and Engineering | Volume 48 | Number 1 | May 1972 | Pages 103-114
Technical Paper | doi.org/10.13182/NSE72-A22460
Articles are hosted by Taylor and Francis Online.
Temperature distributions in an idealized nuclear fuel assembly were computed and studied parametrically. The assembly, which consists of a square array of spacer-free fuel elements, is bounded by an assembly wall and is cooled by longitudinal liquid metal flow. A single-region multicell analysis is used to predict the influence of the fuel assembly wall on the temperature distributions and Nusselt numbers in the idealized assembly. An analytical series solution method couples adjacent cellular temperature-field solutions, and boundary conditions on these and other irregular boundaries are satisfied using a least-squares matching technique. Two slug flow coolant models are considered in the analysis. A global slug flow model assumes a uniform coolant velocity. A cellular slug flow model assigns to each cell a velocity based on its hydraulic diameter. Results of this analysis show that the temperature distributions across the fuel assembly and around each individual fuel element are most strongly influenced by the cellular mass flow rate distribution, which is characterized by a single parameter—the cellular mass flow rate ratio. Fuel assembly temperature gradients are minimized if this ratio is chosen equal to unity. Computations of cellular Nusselt numbers indicate that while steep thermal gradients may exist across the fuel assembly, the Nusselt numbers of all but the cell closest to the wall are unaffected by the presence of the wall. Cellular Nusselt numbers, cellular coolant bulk temperatures, and fuel-element wall temperatures are presented for a range of pitch-to-diameter and cellular mass flow rate ratios.