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Radiation Protection & Shielding
The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
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Conference on Nuclear Training and Education: A Biennial International Forum (CONTE 2025)
February 3–6, 2025
Amelia Island, FL|Omni Amelia Island Resort
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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!
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Fusion Science and Technology
Latest News
Ontario eyes new nuclear development
A 1,300-acre site left undeveloped on the shores of Lake Ontario four decades ago could see new life as the home to a large nuclear facility.
Yasuko Kawamoto, Shigeru Morita, Gakushi Kawamura, Motoshi Goto, Tetsutarou Oishi, Tomoko Kawate, Masahiro Kobayashi, Mamoru Shoji
Fusion Science and Technology | Volume 78 | Number 7 | October 2022 | Pages 537-548
Technical Paper | doi.org/10.1080/15361055.2022.2068897
Articles are hosted by Taylor and Francis Online.
In the Large Helical Device (LHD), a high-performance plasma has been obtained at the inwardly shifted magnetic axis position of Rax = 3.60 m in which a spatial distance between the first wall on the vacuum vessel and the outermost edge boundary of the stochastic magnetic field layer existing outside the last closed flux surface takes a minimum value of ~12 mm at the inboard side. In order to investigate contact between the edge plasma boundary and the inboard first wall, a radial profile of Hβ line emissions at 4861 Å has been measured using a Czerny-Turner visible spectrometer and a 40-channel optical fiber array. All Hβ profiles measured at different magnetic axis positions of Rax = 3.60, 3.75, and 3.90 m showed a centrally peaked profile except for a few fiber channels observing the outboard edge plasma. The Hβ emission near the inboard first wall was negligibly weak, in particular, in the case of Rax = 3.60 m, suggesting no significant contact between the edge boundary plasma and the vacuum vessel first wall. The radial Hβ profile was then analyzed in detail using the EMC3-EIRENE edge plasma simulation code. The simulation well reproduced the measured profiles, including the extremely weak Hβ emission around the inboard first wall in the Rax = 3.60 m configuration. The centrally peaked profiles are found to originate in the Hβ emissions around X-points, while hydrogen neutrals are dominantly localized near the divertor plates. These results confirm the formation of a complete open divertor configuration in the LHD discharge without significant contact with the first wall. The presence of a region with extremely short magnetic field connection lengths (Lc < 5 m) between the inboard first wall and the outermost edge boundary is a key point to eliminate the strong plasma-wall interaction because sustainment of a significant edge plasma is entirely difficult in such a low Lc region.