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Conference Spotlight
2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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Latest News
The current status of heat pipe R&D
Idaho National Laboratory under the Department of Energy–sponsored Microreactor Program recently conducted a comprehensive phenomena identification and ranking table (PIRT) exercise aimed at advancing heat pipe technology for microreactor applications.
Brian C. Kiedrowski, Forrest B. Brown, Jeremy L. Conlin, Jeffrey A. Favorite, Albert C. Kahler, Alyssa R. Kersting, D. Kent Parsons, Jessie L. Walker
Nuclear Science and Engineering | Volume 181 | Number 1 | September 2015 | Pages 17-47
Technical Paper | doi.org/10.13182/NSE14-99
Articles are hosted by Taylor and Francis Online.
Nuclear criticality safety analysis using computational methods such as a Monte Carlo method must establish, for a defined area of applicability, an upper subcritical limit (USL), which is a calculated multiplication factor k that can be treated as actually subcritical and is derived from a calculational margin (combination of bias and bias uncertainty) and a margin of subcriticality. Whisper, a nonparametric, extreme-value method based on sensitivity/uncertainty techniques and the associated software are presented. Whisper uses benchmark critical experiments, nuclear data sensitivities from the continuous-energy Monte Carlo transport software MCNP, and nuclear covariance data to set a baseline USL. Comparisons with a traditional parametric approach for validation, which requires benchmark data to be normally distributed, show that Whisper typically obtains similar or more conservative calculational margins; comparisons with a rank-order nonparametric approach show that Whisper obtains less stringent calculational margins.