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Division Spotlight
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
ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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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RP3C Community of Practice’s fifth anniversary
In February, the Community of Practice (CoP) webinar series, hosted by the American Nuclear Society Standards Board’s Risk-informed, Performance-based Principles and Policies Committee (RP3C), celebrated its fifth anniversary. Like so many online events, these CoPs brought people together at a time when interacting with others became challenging in early 2020. Since the kickoff CoP, which highlighted the impact that systems engineering has on the design of NuScale’s small modular reactor, the last Friday of most months has featured a new speaker leading a discussion on the use of risk-informed, performance-based (RIPB) thinking in the nuclear industry. Providing a venue to convene for people within ANS and those who found their way online by another route, CoPs are an opportunity for the community to receive answers to their burning questions about the subject at hand. With 50–100 active online participants most months, the conversation is always lively, and knowledge flows freely.
Jeffrey A. Moore
Nuclear Technology | Volume 67 | Number 1 | October 1984 | Pages 66-72
Technical Paper | Nuclear Safety | doi.org/10.13182/NT84-A33530
Articles are hosted by Taylor and Francis Online.
The nonrandom packing of fuel rod debris around and above the surviving fuel rod segments in a degraded core was analyzed with the spacer grids modeled as a porous floor. The irregular shape of the debris was simulated by assuming that all of the spherical particles terminate their migration within the debris bed at their first two-point contact. The analytical approach was verified by comparing the computational results with experimental data for nonrandom packing. Specific calculations for the Three-Mile Island Unit 2 geometry reveal an average (horizontally integrated) nonrandom packing density between the fuel rods of ∼0.30. If simulated vibrations are imposed, this value increases to 0.50. If the debris bed builds up above the fuel rod stubs, the average (horizontally integrated) packing density above these rods reaches a value of ∼0.38 without vibrations; loosely packed gravel has an average random packing density of 0.45.
