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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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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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ANS joins others in seeking to discuss SNF/HLW impasse
The American Nuclear Society joined seven other organizations to send a letter to Energy Secretary Christopher Wright on July 8, asking to meet with him to discuss “the restoration of a highly functioning program to meet DOE’s legal responsibility to manage and dispose of the nation’s commercial and legacy defense spent nuclear fuel (SNF) and high-level radioactive waste (HLW).”
Rakesh Chawla, Om Parkash Joneja, Marc Rosselet, Tony Williams
Nuclear Technology | Volume 139 | Number 1 | July 2002 | Pages 50-60
Technical Paper | Reactor Safety | doi.org/10.13182/NT02-A3303
Articles are hosted by Taylor and Francis Online.
Although high-temperature reactors (HTRs) are endowed with a number of inherent safety features, there are still aspects of the design that need particular attention. For concepts in which shutdown rods are situated outside the core region, as is the case in contemporary modular pebble bed designs, accurate calculations are needed for the worth of these shutdown rods not only in normal operation but also under accident conditions in which significant changes occur, for instance, due to inadvertant moderation increase in the core (ingress of water or other hydrogeneous compound). Corresponding validation experiments, employing a variety of reactivity measurement techniques, were conducted in the framework of the HTR-PROTEUS program employing low-enriched uranium pebble-type fuel. Details of the experimental configurations, along with the measurement results obtained, are given for two different HTR-PROTEUS cores, in each of which four different shutdown rod combinations were investigated. Comparisons made with calculations, based on both approximative deterministic models and geometrically "near-to-exact" Monte Carlo analyses, have clearly brought out the sensitivity of the experimental results to calculational correction factors when conventional (thermal) techniques are used for reactivity measurements in such systems. Considerably greater systematic accuracies are reflected in the experimental shutdown rod values obtained using specially developed epithermal techniques, and it is these results that are recommended for benchmarking purposes.