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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
TerraPower begins U.K. regulatory approval process
Seattle-based TerraPower signaled its interest this week in building its Natrium small modular reactor in the United Kingdom, the company announced.
TerraPower sent a letter to the U.K.’s Department for Energy Security and Net Zero, formally establishing its intention to enter the U.K. generic design assessment (GDA) process. This is TerraPower’s first step in deployment of its Natrium technology—a 345-MW sodium fast reactor coupled with a molten salt energy storage unit—on the international stage.
M. D. Freshley
Nuclear Technology | Volume 15 | Number 2 | August 1972 | Pages 125-176
Technical Paper | Plutonium Utilization in Commercial Power Reactors / Reactor | doi.org/10.13182/NT72-A31143
Articles are hosted by Taylor and Francis Online.
The satisfactory irradiation performance of several types of mixed-oxide fuels suitable for the utilization of plutonium in thermal reactors was demonstrated by a significant number of experiments performed in the Plutonium Recycle Test Reactor (PRTR). Heterogeneously and homogeneously enriched packed-particle and pellet mixed-oxide fuels were irradiated at peak linear heat ratings higher, i.e., >655 W/cm (>20 kW/ft), than those employed in the most advanced commercial reactors to significant burnups, i.e., >18 000 MWd/MTM. Early experience in PRTR provided some of the first data related to the effects of hydrogenous impurities on Zircaloy-clad mixed-oxide fuel performance. The demonstrated solution to the problem was achieved through the development of improved analytical and fuel fabrication techniques. Fuel rod cladding becomes oval shaped during irradiation due to creep collapse with the degree of ovality varying among the different fuel types. The fission gas release fraction for vipac mixed-oxide fuels varies linearly from a value of 0.05 for a volumetric average temperature of 600°C to essentially 1.00 for a volumetric average temperature of 2250°C. Homogenization of the PuO2 particles in mechanically mixed UO2-PuO2 commences at fuel temperatures sufficient to cause sintering and equiaxed grain formation during irradiation. PRTR experience indicates that a fuel-cladding reaction that is stoichiometry dependent occurs in Zircaloy-clad mixed-oxide fuels. The satisfactory defect performance of mixed-oxide fuels was demonstrated by several in-service and intentionally defected experiments although there are indications that defect performance may constitute an operating limit at very high linear heat ratings.
