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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
International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
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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Latest News
Dragonfly, a Pu-fueled drone heading to Titan, gets key NASA approval
Curiosity landed on Mars sporting a radioisotope thermoelectric generator (RTG) in 2012, and a second NASA rover, Perseverance, landed in 2021. Both are still rolling across the red planet in the name of science. Another exploratory craft with a similar plutonium-238–fueled RTG but a very different mission—to fly between multiple test sites on Titan, Saturn’s largest moon—recently got one step closer to deployment.
On April 25, NASA and the Johns Hopkins University Applied Physics Laboratory (APL) announced that the Dragonfly mission to Saturn’s icy moon passed its critical design review. “Passing this mission milestone means that Dragonfly’s mission design, fabrication, integration, and test plans are all approved, and the mission can now turn its attention to the construction of the spacecraft itself,” according to NASA.
Kenneth Hoar, Piotr Nowinski, Vernon Hodge, James Cizdziel
Nuclear Technology | Volume 175 | Number 1 | July 2011 | Pages 351-359
Technical Paper | Special Issue on the 16th Biennial Topical Meeting of the Radiation Protection and Shielding Division / Environmental Effects of Nuclear Technology | doi.org/10.13182/NT11-A12307
Articles are hosted by Taylor and Francis Online.
Rock varnish samples were collected near three point sources of air pollution to determine if the varnish contained a record of recent air pollution. Samples were collected as follows: downwind of the Nevada Test Site (NTS); in the fallout pattern of the shuttered Mohave Power Plant, located in Laughlin, Nevada; and, near the operating Reid-Gardner Power Plant, just east of Las Vegas, Nevada. Analysis of the NTS rock varnish shows 240Pu/239Pu mass ratios as low as 0.0592 ± 0.0003 and 241Pu/239Pu ratios as low as 0.00063 ± 0.00004, compared to worldwide values of 0.18 ± 0.01 and 0.009 ± 0.002, respectively, clearly indicating that the varnish can be used as a forensic tool for identifying the source of air pollution, in this case the NTS. The samples collected in the plumes of the coal-fired power plants contain thorium and uranium, and have 232Th/238U mass ratios from 1 to 30, and concentrations from 5 to 755 ppm for Th and 1 to 578 ppm for U. The highest concentrations of these elements occur together at locations that implicate the power plants; however, additional samples would be required to demonstrate unequivocally that the power plants are the sources. Overall, it is apparent that rock varnish can be utilized as a passive monitor to investigate recent air pollution.
