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.
Division Spotlight
Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
Meeting Spotlight
2025 ANS Annual Conference
June 15–18, 2025
Chicago, IL|Chicago Marriott Downtown
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!
Latest Magazine Issues
Jun 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
July 2025
Nuclear Technology
June 2025
Fusion Science and Technology
Latest News
Zaporizhzhia ‘extremely fragile’ relying on single off-site power line, IAEA warns
Europe’s largest nuclear power plant has just one remaining power line for essential nuclear safety and security functions, compared with its original 10 functional lines before the military conflict with Russia, warned Rafael Mariano Grossi, director general of the International Atomic Energy Agency.
G. Dell'Orco, M. Simoncini, D. Zito, G. Vella
Fusion Science and Technology | Volume 39 | Number 2 | March 2001 | Pages 644-648
Fusion Materials | doi.org/10.13182/FST01-A11963311
Articles are hosted by Taylor and Francis Online.
Both the EU Long Term Programmes for DEMO and the ITER R&D foresee the thermal-mechanical qualification of the beryllium, as neutron multiplier, and lithium orthosilicate or lithium metatitanate as breeder ceramics pebble beds. FZK has performed measurements on the pebble bed thermal-mechanical properties using cylindrical test sections. Using an alternative approach, ENEA, has launched similar testing on the SMARTS mock-up, reproducing on a small scale the reactor reference plane geometry1 instead. The tests have shown that the pebble bed thermal behaviour is strongly affected by the initial filling Packing Factor (PF). In fact, the higher the PF, the higher the thermal conductivity of the bed. Therefore, if the neutron multiplication needs an increase in the pebble PF, the only possibility is to adopt binary pebble beds (small pebbles infiltrating between larger ones) as an alternative to the mono-sized lattice. Using binary pebble beds, the filling quality should be guaranteed against the occurrence of de-mixing or swimming of the larger pebbles over the smaller ones during the thermal transients. A possible solution is to optimise the filling procedure, to improve the PF and its relevant thermal performance, and also to achieve a stable bed lattice during the cycling loads. In this case, the mechanical characteristics of the pebble beds would also be heavily affected, thus requiring a new tests campaign to determine the actual mechanical properties of an “optimised” pebble bed. This paper presents a new filling optimisation method and the experimental results from the compression tests of optimised pebble beds.