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September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Moving past Sayre’s Law on low-dose radiation
Craig Piercycpiercy@ans.org
So, President Trump has just kicked the low-dose radiation hornets’ nest.
Specifically, his recently signed executive order “Ordering the Reform of the Nuclear Regulatory Commission” calls for the NRC to “reconsider reliance” on the linear no-threshold (LNT) theory and the ALARA (as low as reasonably achievable) standard for radiation protection.
This directive will certainly reignite a vociferous debate within the radiation research community over the continued efficacy of using LNT as the basis for protecting the public and the environment, a community that has been wracked with controversy on this matter for the last few years.
I must admit that whenever the low-dose issue comes up, my first thoughts always go to Sayre’s Law.
A. Ibrahim, D. L. Henderson, L. A. El-Guebaly, P. P. H. Wilson, M. E. Sawan, ARIES Team
Fusion Science and Technology | Volume 56 | Number 2 | August 2009 | Pages 726-730
Nuclear Analysis | Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2) | doi.org/10.13182/FST09-A8994
Articles are hosted by Taylor and Francis Online.
The effects of neutron streaming through the divertor He-access pipes of the ARIES compact stellarator fusion power plant on the shielding performance of its components were investigated in this analysis. A 3-D analysis for the most promising design of the He-access pipe with shielding plug and inserts indicated that neutron attenuation through the shielded pipe is not sufficient to eliminate the issue of neutron streaming. The results show that the damage exceeded the limits near the pipe for the manifold, vacuum vessel, and magnet. Precautions should be taken that include changing the pipe design and orientation, avoiding rewelding the manifold and vacuum vessel near the pipe, and/or relocating the magnet away from the pipe. The neutron flux behind the pipe is excessive, mandating additional local shield (∼1 m) to protect the externals.