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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.
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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
Argonne’s METL gears up to test more sodium fast reactor components
Argonne National Laboratory has successfully swapped out an aging cold trap in the sodium test loop called METL (Mechanisms Engineering Test Loop), the Department of Energy announced April 23. The upgrade is the first of its kind in the United States in more than 30 years, according to the DOE, and will help test components and operations for the sodium-cooled fast reactors being developed now.
Edwin M. Larsen, S. I. Abdel-Khalik, Mark S. Ortman
Nuclear Technology | Volume 41 | Number 1 | November 1978 | Pages 12-26
Technical Paper | Reactor | doi.org/10.13182/NT78-A32129
Articles are hosted by Taylor and Francis Online.
The 1000-MW(electric) laser fusion reactor design of the University of Wisconsin, SOLASE, is fueled by inserting cryogenic deuterium-tritium pellets containing a milligram of fuel into a spherical cavity having a 6-m radius at a rate of 20 Hz. The cavity is surrounded by a honeycomb graphite structure divided into 16 longitudinal segments through which lithium oxide particles (100 to 200 µm in diameter and with a pore length of 1 µm) flow by gravity. The total oxide inventory is 1 mg. The lithium oxide, which contains 0.1 wt% water, serves as both a tritium breeder and a heat transport medium. The oxide enters the blanket at 673 K and exits at 873 K except for a 2% side stream exiting at 1123 K, from which the tritium is recovered. At this temperature, a residence time of 300 s at a flow rate of 163 kg/s is required to condense the daily tritium supply as HTO on a cold surface. The 873 K lithium oxide is transported to a steam generator fabricated from Croloy tubes. In addition to the fuel, the container, either borosilicate glass or polyvinylalcohol (PVA), and a polymer ablator, the pellets contain a high-Z material, here xenon. Also, ∼30 mg of neon are frozen on the outside surface to ensure cryogenic conditions during flight. Some pellet constituents will react with the wall, resulting in erosion. Unburned hydrogen species will react with graphite to form acetylene at a rate estimated to be 63 pm/s (2 mm/yr) for glass and PVA shells at pumping speeds of 6.4 and 8.4 Pa · m3/s (4.8 × 104 and 6.3 × 104 Torr · ℓ/s) at 300 K, respectively. The oxygen debris will erode the graphite by carbon monoxide formation at maximum rates of 6.3 and 25.4 pm/s, respectively, for glass and PVA shells. The total erosion rate is within the expected lifetime of the blanket (1 yr) based on radiation damage studies. The reactor exhaust is predominantly neon, so that hydrogen isotope recovery and recycle is essentially a neon purification process. The fill time for glass pellets is estimated to be 5 days and for PVA pellets, 1 day. This results in a total tritium inventory of 26 and 11 kg, respectively, for a lithium oxide blanket containing 1 kg of tritium. Anticipated tritium losses include 1.5 to 2.2 kBq/kg H2O (40 to 60 nCi/ℓ H2O) of tritium to the water in the reheaters and steam generators and <400 kBq/s (1 Ci/day) for atmospheric losses. This study shows the necessity for experimental work on the thermodynamic properties of well-characterized lithium oxide.