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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.
G. Srikantiah
Nuclear Science and Engineering | Volume 24 | Number 2 | February 1966 | Pages 175-183
Technical Paper | doi.org/10.13182/NSE66-A18302
Articles are hosted by Taylor and Francis Online.
Methods of long-term reactivity control for plutonium-fueled D2O-moderated reactors that favor high conversion ratios are considered. One method uses annular gaps around the fuel elements that can be selectively filled with the D2O moderator. Reactivity compensations ranging from 8 to 15% can be achieved with gaps of 6 to 8-cm thickness and a corresponding reduction in conversion ratio of 3 to 5%. In the second method, depleted uranium sleeves that can be removed as required during long-term operation are utilized around fuel elements in annular regions of the reactor. Sleeves of only 0.2-cm thickness, around fuel elements in the central region of the reactor, provide reactivity compensations of up to 10% and actually increase the conversion ratio in the design studied. Average conversion ratios of about 0.90 are obtained in a large D2O-cooled and -moderated reactor using Zircaloy pressure tubes at fuel burnup of 104 MWd/t. The average conversion ratios would increase to about 0.97 if beryllium-based pressure tubes could be developed.
