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2026 Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
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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Seconds Matter: Rethinking Nuclear Facility Security for the Modern Threat Landscape
In today’s rapidly evolving threat environment, nuclear facilities must prioritize speed and precision in their security responses—because in critical moments, every second counts. An early warning system serves as a vital layer of defense, enabling real-time detection of potential intrusions or anomalies before they escalate into full-blown incidents. By providing immediate alerts and actionable intelligence, these systems empower security personnel to respond decisively, minimizing risk to infrastructure, personnel, and the public. The ability to anticipate and intercept threats at the earliest possible stage not only enhances operational resilience but also reinforces public trust in the safety of nuclear operations. Investing in such proactive technologies is no longer optional—it’s essential for modern nuclear security.
H. K. Clark
Nuclear Science and Engineering | Volume 24 | Number 2 | February 1966 | Pages 133-141
Technical Paper | doi.org/10.13182/NSE66-A18298
Articles are hosted by Taylor and Francis Online.
The influence of the distribution of 235U, 239Pu, and 233U in water on the minimum critical mass, the minimum critical concentration per unit length of cylinder, and the minimum critical mass per unit area of slab surface is calculated. Two energy groups are employed in the calculations with parameters normalized to force agreement between calculations and experiments performed with water-reflected spheres containing uniform aqueous solutions having a wide range of concentrations. Calculations made with these parameters for a water-reflected cylinder, in which the optimum distribution for minimum mass was approximated within five coaxial regions, agree well with experimental results. Minimum critical masses, concentrations per unit length of cylinder, and masses per unit area calculated for 235U, 239Pu, and 233U are, respectively, 768 g, 16.9 g/cm, 0.417 g/ cm2; 492 g, 10.6 g/cm, 0.266 g/cm2; and 571 g, 13.5 g/cm, 0.362 g/cm2.
