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
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.
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!
Latest Magazine Issues
Jul 2024
Jan 2024
Latest Journal Issues
Nuclear Science and Engineering
August 2024
Nuclear Technology
Fusion Science and Technology
Latest News
ARPA-E announces $40 million to develop transmutation technologies for UNF
The Department of Energy’s Advanced Research Projects Agency–Energy (ARPA-E) announced $40 million in funding to develop cutting-edge technologies to enable the transmutation of used nuclear fuel into less-radioactive substances. According to ARPA-E, the new initiative addresses one of the agency’s core goals as outlined by Congress: to provide transformative solutions to improve the management, cleanup, and disposal of radioactive waste and spent nuclear fuel.
Paolo Bianchini, Manuele Aufiero, Francesco Di Lecce
Nuclear Science and Engineering | Volume 197 | Number 12 | December 2023 | Pages 3022-3034
YMSR Paper | doi.org/10.1080/00295639.2023.2219818
Articles are hosted by Taylor and Francis Online.
Fuel channel flow blockage is a postulated accident scenario in graphite-moderated molten salt reactors (MSRs), caused by debris partially obstructing the flow in a hole inside a graphite moderator brick. This obstruction produces an increase in the fuel salt bulk temperatures in the blocked channel, resulting in a significant fraction of the deposited fission power being conducted through graphite from the blocked channel to the surrounding unblocked channels. In the blocked channel, a combination of forced convection and natural convection takes place, the latter being dominant at very strong flow rate reductions. At full blockage (with the fragment completely obstructing the flow), because of the poor thermal conductivity of fuel salt, correct estimation of the natural convection impact on heat transfer between the channel bulk and the walls is fundamental to determine whether boiling conditions are reached in the blocked channel. The proposed assessing approach, developed in collaboration with ThorCon in the frame of the ThorCon reactor core design and optimization, is presented in this work. Results from a case study based on the molten salt breeder reactor (MSBR) design and operating conditions are presented and discussed. These analyses show that with respect to full blockage accidents in other reactor types, the consequences of full channel blockage accidents in graphite-moderated MSRs are milder. For graphite-moderated MSRs, the main mechanical limits during the accident arise in thermal stresses in the graphite brick. Graphite thermal and mechanical properties, namely, bulk modulus, thermal expansion coefficient, ultimate strength, and thermal conductivity, are severely impacted by neutron irradiation through the life of the graphite. All these effects are taken into account in the current analysis and are discussed in the present work.