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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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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Deep Space: The new frontier of radiation controls
In commercial nuclear power, there has always been a deliberate tension between the regulator and the utility owner. The regulator fundamentally exists to protect the worker, and the utility, to make a profit. It is a win-win balance.
From the U.S. nuclear industry has emerged a brilliantly successful occupational nuclear safety record—largely the result of an ALARA (as low as reasonably achievable) process that has driven exposure rates down to what only a decade ago would have been considered unthinkable. In the U.S. nuclear industry, the system has accomplished an excellent, nearly seamless process that succeeds to the benefit of both employee and utility owner.
Samuel E. Bays, Joseph Nielsen, Joshua Cogliati, Charles Wemple
Nuclear Technology | Volume 208 | Number 5 | May 2022 | Pages 811-821
Technical Paper | doi.org/10.1080/00295450.2021.1980320
Articles are hosted by Taylor and Francis Online.
The neutronics software, HELIOS, was validated in 2015 for performing core reload design and safety analysis of the Advanced Test Reactor. However, when HELIOS was benchmarked against historic fission-wire measurements (i.e., zero-power full-core measurements), a statistically resolved calculation-to-measurement bias was discovered. The azimuthal power along each fuel plate computed by HELIOS has consistently shown to underpredict measurements made by fission wires in historic zero-power tests near the fuel element side plates.
It was hypothesized during the HELIOS software validation work that this bias is attributable to local moderation in coolant vents in the side plates axially just above and below the fission wires on the fuel plate edges. This work used detailed MCNP and MC21 models of the side plate vents to test this hypothesis. By comparing the average azimuthal biases between HELIOS and two-dimensional and three-dimensional (3-D) MCNP models and a 3-D MC21 model, it was found that the HELIOS azimuthal bias is not due to the measurement.
