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Division Spotlight
Reactor Physics
The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
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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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.
G. F. Kessinger, A. R. Jurgensen, D. M. Missimer, J. S. Morrell
Nuclear Technology | Volume 171 | Number 1 | July 2010 | Pages 108-122
Technical Paper | Radioisotopes | doi.org/10.13182/NT10-A10775
Articles are hosted by Taylor and Francis Online.
The ultimate purpose of this study was to investigate the use of a Li-Ca mixture for direct reduction of actinide oxides to actinide metals at temperatures below 1500°C. For such a process to be successful, the products of the reduction reaction, actinide metals, Li2O, and CaO must all be liquid at the reaction temperature so that the resulting actinide metal can coalesce and be recovered as a monolith. Since the established melting temperature of Li2O is in the range of 1427 to 1700°C and the melting temperature of CaO is 2654°C, the Li2O-CaO (lithium oxide-calcium oxide) pseudobinary system was investigated in an attempt to identify the presence of low-melting eutectic compositions.The results of our investigation indicate that there is no evidence of ternary Li-Ca-O phases or solutions melting below 1200°C. In the 1200 to 1500°C range utilizing MgO crucibles, there is some evidence for the formation of a ternary phase; however, it was not possible to determine the phase composition. The results of experiments performed with ZrO2 crucibles in the same temperature range did not show the formation of the possible ternary phase seen in the earlier experiment involving MgO crucibles, so it was not possible to confirm the possibility that a ternary Li-Ca-O or Li-Mg-O phase was formed. It appears that the Li2O-CaO materials reacted, to some extent, with all of the container materials, alumina (Al2O3), magnesia (MgO), zirconia (ZrO2), and 95% Pt-5% Au; however, to clarify the situation additional experiments are required.In addition to the primary purpose of this study, the results of this investigation led to the following conclusions. First, the melting temperature of Li2O may be as low as 1250°C, which is considerably lower than the previously published values in the range 1427 to 1700°C. Second, lithium oxide (Li2O) vaporizes congruently. Third, lithium carbonate and Li2O react with 95% Pt-5% Au and also react with pure Pt. Fourth, it is likely that some or all of the past high-temperature phase behavior and vaporization experiments involving Li2O(s) at temperatures above 1250°C have actually involved Li2O(l). If these past measurements were actually measurements performed on Li2O(l) instead of the solid, the thermochemical data for phases and species in the Li-O system will require reevaluation.
