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Division Spotlight
Fusion Energy
This division promotes the development and timely introduction of fusion energy as a sustainable energy source with favorable economic, environmental, and safety attributes. The division cooperates with other organizations on common issues of multidisciplinary fusion science and technology, conducts professional meetings, and disseminates technical information in support of these goals. Members focus on the assessment and resolution of critical developmental issues for practical fusion energy applications.
Meeting Spotlight
Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
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
Virginia utility considers SMRs
Dominion Energy Virginia has issued a request for proposals from leading nuclear companies to study the feasibility of putting a small modular reactor at its North Anna nuclear power plant.
While the utility says it is not a commitment to build an SMR at the site, the RFP is “an important first step in evaluating the technology and the North Anna site to support Dominion Energy customers’ future energy needs consistent with the company’s most recent Integrated Resource Plan.”
Brent B. Bredehoft, Robert D. Busch
Nuclear Technology | Volume 102 | Number 2 | May 1993 | Pages 259-269
Technical Paper | Nuclear Criticality Safety | doi.org/10.13182/NT93-A34821
Articles are hosted by Taylor and Francis Online.
In tabulating critical data, the hydrogen-to-fissile atom ratio (H/X) is commonly used to characterize the amount of moderation in a system. Though adequate in many cases, H/X does not account for the moderating contribution of other light nuclei contained in common uranium-moderator mixtures. This ratio also does not account for enrichment of the system, which affects the resonance absorption characteristics and, therefore, the moderating behavior of that system. To alleviate these problems, a two-energy-group diffusion theory analogy to the six-factor formula was applied to define a new parameter p/(η2 · f2), which describes the moderation characteristics or the “thermalness” of a fissioning system and includes the effects of enrichment and the presence of moderators other than hydrogen. From an analysis of several low-enriched uranium systems with different moderators, it was found that the values of p/(η2·f2) corresponding to minimum critical mass and volume tend to center in a narrower range than do the values of H/X for the same systems. Also, the thermalness parameter does not vary with the addition of a reflector and is applicable to systems with other than hydrogenous moderators. Based on these results, the thermalness parameter p/(η2 · f2) provides an effective means of characterizing moderated systems relative to optimum conditions.
