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Conference Spotlight
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.
Markku Rajamäki, Frej Wasastjerna
Nuclear Science and Engineering | Volume 101 | Number 1 | January 1989 | Pages 41-47
Technical Paper | doi.org/10.13182/NSE89-A23593
Articles are hosted by Taylor and Francis Online.
The reactivity effects caused by fragmentation of nuclear fuel and by simultaneous cooling of the fragments are described. A series of light water reactor (LWR) cases and three speculative scenarios for the Chernobyl accident are considered. Calculations were carried out with the LWR cell burnup code CASMO-HEX. Fragmentation is described by increasing the number of fuel pieces while decreasing their diameter. Cooling is considered to occur as quasi-stationary. Relative movement of the fragments and the coolant is taken into account by varying the water/fuel ratio. Under certain circumstances, substantial reactivity increases are found to occur in both reactor types. These may have contributed significantly to the severity of the Chernobyl accident.
