ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
2026 Nuclear Energy Conference & Expo (NECX)
August 24–27, 2026
Dallas, TX|Hilton Anatole
Latest Magazine Issues
Aug 2026
Jan 2026
2026
Latest Journal Issues
Nuclear Science and Engineering
October 2026
Nuclear Technology
September 2026
Fusion Science and Technology
August 2026
Latest News
Front-end nuclear fuel supply cooperation: Turning allied interdependence into strategic advantage
The global nuclear revival, which is fueled by unprecedented demand for firm, affordable, dispatchable power for artificial intelligence and data center build-out, energy security imperatives, and climate commitments, has exposed a structural reality of the Western fuel cycle: No single allied nation currently possesses the full suite of front-end capabilities. From mining through conversion, enrichment, fabrication, and the emerging deconversion and metallization steps required for reactor fuels, capability is distributed across Canada, France, Japan, the United Kingdom, and the United States (collectively, the “Sapporo Five”), as well as a small group of close partners.
O. E. Dwyer
Nuclear Science and Engineering | Volume 25 | Number 4 | August 1966 | Pages 343-358
Technical Paper | doi.org/10.13182/NSE66-A18553
Articles are hosted by Taylor and Francis Online.
Circumferential variations of temperature and local heat transfer coefficients were obtained for sodium flowing in-line through a staggered rod bundle. The conditions of the study were: turbulent flow, uniform heat flux from the surfaces of all rods, and fully developed velocity and temperature profiles. The rods were spaced in an equilateral triangular array, and the pitch:diameter (P:D) ratio was varied down to 1.10. It was shown that the annulus model is satisfactory for estimating average heat transfer coefficients for P:D ratios down to about 1.3, but below this, it gives increasingly high results, e.g., at P:D = 1.10, an annulus-model coefficient can be high by about a factor of 2. It was found that circumferential temperature variations are not large, e.g., at P:D = 1.10, this variation is about twice the average temperature drop from the rod surface to flowing metal. Compared to the P:D ratio, the Peclet number has little influence on the reduction in the average heat transfer coefficient, or the circumferential variation of the surface temperature. At a P:D ratio of 1.40, the local coefficient is estimated to vary by a factor of only 1.2; at 1.20, by a factor of 1.7; and at 1.10, by a factor of ≈ 100.