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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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Latest News
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.
B. Becker, A. Weltz, J. A. Kulisek, J. Thompson, N. Thompson, Y. Danon
Nuclear Science and Engineering | Volume 175 | Number 2 | October 2013 | Pages 124-134
Technical Paper | doi.org/10.13182/NSE12-66
Articles are hosted by Taylor and Francis Online.
The use of a lead slowing-down spectrometer (LSDS) is considered as a possible option for nondestructive assay of fissile material of used nuclear fuel. The primary objective is to quantify fissile isotopes, particularly 239Pu and 235U, via a direct measurement distinguishing them through their characteristic fission spectra in the LSDS. In this paper, we present several assay measurements performed at the Rensselaer Polytechnic Institute (RPI) to support ongoing feasibility studies of the method and to provide benchmark experiments for Monte Carlo calculations of the assay system. A fresh uranium oxide fuel rod from the RPI Walthousen Reactor Critical Facility, a 239Pu-Be source, and several highly enriched 235U disks were assayed in the LSDS. The characteristic fission spectra were measured with 238U and 232Th threshold fission chambers, which are primarily sensitive to fission neutrons with energies above the threshold. Despite the constant neutron and gamma background from the Pu-Be source and the intense interrogation neutron flux, the LSDS system was able to measure the characteristic 235U and 239Pu responses. All measurements were compared to Monte Carlo simulations complementing previous modeling-based studies. It is shown that the available simulation tools and models are well suited to simulate the assay. An absolute calibration technique of the LSDS, which is required to perform quantitative measurements of the assayed fissile materials, is presented.
