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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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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.
Kousaku Fukuda, Ekkehard Groos, John Rau
Nuclear Technology | Volume 69 | Number 3 | June 1985 | Pages 368-379
Technical Paper | Nuclear Fuel | doi.org/10.13182/NT85-A33618
Articles are hosted by Taylor and Francis Online.
Diffusion behavior of some metallic fission products in high-temperature reactor fuel elements, which had been irradiated in an in-pile gas loop (Saphir) installed in the Pégase reactor (France), was studied. Diffusion coefficients of cesium and silver in hightemperature isotropic pyrolytic carbon and graphite matrix under in-pile conditions were obtained by analyzing the concentration profiles of the fission products in the fuel elements, which had been measured by postirradiation examination. Although ruthenium profiles were measured, analysis of the diffusion coefficients could not be carried out because of the virtually flat distributions. By comparing the concentrations of the cesium isotopes in the fuel-free zone of the elements, it was found that 134Cs behaved anomalously in the graphite matrix, which was, probably, caused by activation of an undetectable amount of 133Cs impurity involved in the matrix. For the extremely high concentration of these fission products, which had been observed near the surface of the element, two causes, the uranium contamination concentrating there and the trapping effect in the defects introduced by fission of the locally concentrated uranium, were considered, although these high concentrations of the fission products were neglected in the analysis. Furthermore, transport behavior of the fission products through the gas gap from the fuel element to the graphite tube containing the elements was studied by measuring the concentration profiles in the tube. It was concluded that ruthenium transport occurred by direct fission recoil from the surface uranium contamination, whereas that of cesium, by desorption from the surface.
