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
2024 ANS Annual Conference
June 16–19, 2024
Las Vegas, NV|Mandalay Bay Resort and Casino
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
Apr 2024
Jan 2024
Latest Journal Issues
Nuclear Science and Engineering
May 2024
Nuclear Technology
Fusion Science and Technology
Latest News
Glass strategy: Hanford’s enhanced waste glass program
The mission of the Department of Energy’s Office of River Protection (ORP) is to complete the safe cleanup of waste resulting from decades of nuclear weapons development. One of the most technologically challenging responsibilities is the safe disposition of approximately 56 million gallons of radioactive waste historically stored in 177 tanks at the Hanford Site in Washington state.
ORP has a clear incentive to reduce the overall mission duration and cost. One pathway is to develop and deploy innovative technical solutions that can advance baseline flow sheets toward higher efficiency operations while reducing identified risks without compromising safety. Vitrification is the baseline process that will convert both high-level and low-level radioactive waste at Hanford into a stable glass waste form for long-term storage and disposal.
Although vitrification is a mature technology, there are key areas where technology can further reduce operational risks, advance baseline processes to maximize waste throughput, and provide the underpinning to enhance operational flexibility; all steps in reducing mission duration and cost.
M. Kobayashi, Y. Feng, S. Morita, S. Masuzaki, N. Ezumi, T. Kobayashi, M. B. Chowdhuri, H. Yamada, T. Morisaki, N. Ohyabu, M. Goto, I. Yamada, K. Narihara, A. Komori, O. Motojima, LHD Experiment Group
Fusion Science and Technology | Volume 58 | Number 1 | July-August 2010 | Pages 220-231
Chapter 5. Divertor and Edge Physics | Special Issue on Large Helical Device (LHD) | doi.org/10.13182/FST10-A10809
Articles are hosted by Taylor and Francis Online.
Transport characteristics of the stochastic magnetic boundary of the Large Helical Device (LHD) are investigated, based on three-dimensional Monte-Carlo Braginskii-type fluid model code, EMC3, coupled with the kinetic neutral transport code EIRENE, in direct comparison with experimental observations for aspects of the relation between the magnetic topology and the resulting transport in terms of counter acting flux tube flows and impurity screening/transport. Divertor probe measurements show a rather weak divertor parameter dependence on upstream density in contrast to those of tokamaks at high-recycling regime. This is found to be due to the loss of parallel momentum via cross-field interaction between the stochastic flux tubes, where strong flow shear exists. The three-dimensional modeling predicts an impurity screening potential of the stochastic scrape-off layer (SOL) at high densities. The remnant island geometry affects the energy transport, which leads to suppression of the thermal forces by increasing cross-field energy flux across islands at high collisionality. The screening effect is most pronounced at the edge surface layers with a strong friction force exerted by the background plasma flow, where the flow toward divertor is enhanced due to the rich ionization source. Modeling results are compared to the edge carbon emission obtained in experiments, where a reasonable agreement on the density dependence is found, indicating the existence of the impurity screening mechanism in the stochastic SOL of LHD.