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Conference Spotlight
2026 Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
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!
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Star Trek or Planet of the Apes?
Craig Piercycpiercy@ans.org
These days, the ship of civil nuclear technology we are all aboard is sailing through a turbulent passage. The winds and currents are favorable, but there are swells ahead: steep energy-demand projections, buoyant equity valuations, splashy announcements, a generational realignment of nuclear policies and institutional norms.
Part of the reason we chose “Building the Nuclear Century” as the theme for this year’s Winter Conference was to put some ballast in the hull of the nuclear conversation.
Advanced nuclear fission and fusion energy development are accelerating, both here and around the world. And yet, at least in the U.S., we are still years away from connecting commercial Gen IV systems to our grid.
In a world growing increasingly impatient, how do we stay on task and deliver? There are three ingredients to success.
T. E. Gebhart, L. R. Baylor, S. J. Meitner
Fusion Science and Technology | Volume 77 | Number 1 | January 2021 | Pages 33-41
Technical Paper | doi.org/10.1080/15361055.2020.1842682
Articles are hosted by Taylor and Francis Online.
Shattered pellet injector systems have been installed on DIII-D, JET, and KSTAR and used to experimentally determine the effectiveness of the shattered pellet injection (SPI) process in mitigating the deleterious effects of a tokamak plasma disruption. Pellets are fired, and before entering the plasma, strike a bent tube known as a shatter tube causing the pellet to shatter. The process of pellet fragmentation is a chaotic process that can be described in terms of fragment size distribution through a statistical model that incorporates the effects of the pellet material and impact characteristics. In addition to the fragment size distribution, the shatter plume has other characteristics of interest, such as a fragment velocity distribution and temporal mass evolution. The fragment velocity distribution is important because it is needed to accurately model the spread and location of the ablation and the deposition of impurities in the plasma over time. The temporal mass evolution is necessary to determine the time-resolved delivery of mass to the plasma.
Due to installation constraints, the shatter tube currently installed on JET has a unique geometry with a modest S-bend followed by a 20-deg bend at the end of the tube. The DIII-D and KSTAR shatter tube design is a simple tube bent through an angle of 20 deg followed by a straight section. The resulting shatter sprays from the JET shatter tube and a 20-deg miter bend shatter tube were experimentally characterized for various pellet materials and speeds. Laboratory testing of these shatter tubes allows for the use of fast cameras to capture the fragment spray traveling through a large vacuum chamber. These high-speed videos of the shatter plumes allow the fragment size distribution, temporal mass evolution, and velocity distribution of the fragments within the plume to be determined. This paper presents a comparison of the unique geometry of the JET shatter tube to the miter bend geometries used for shattering and some insight into the variables that may be adjusted to produce the optimal shatter spray. The impact of entrained propellant gas on the resulting shatter spray was examined during testing.
