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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.
J. T. Wajima, H. Yamamoto, H. Kikuchi, T. Ohnishi, S. Kobayashi
Nuclear Science and Engineering | Volume 31 | Number 1 | January 1968 | Pages 19-31
Technical Paper | doi.org/10.13182/NSE68-A18004
Articles are hosted by Taylor and Francis Online.
The microparameters including the thermal-neutron disadvantage factor, DF, the epi- to sub-Cd neutron capture ratio in 238U, ρ28, the epi- to sub-Cd fission ratio in 235U, δ25, and the ratio of the epi-Cd 238U fission to the sub-Cd 235U fission, δ28, were measured in the Ozenji Critical Facility for a seven-rod clustered nuclear superheat fuel element. The factors f, p, and ϵ were derived therefrom and the effect of 235U epithermal fissions on the neutron multiplication factor was observed to be 1.5% Δk/k. Flooding changed the individual factors f, p, and ϵ by amounts corresponding to −6.8% Δk/k, +4.7% Δk/k, and −2.9% Δk/k, respectively, yielding an overall change of −5.1% Δk/k. The maximum discrepancies between measurement and calculation are 1 to 3% for DF, ρ28 , δ25, and δ28; 0.3% Δk/k for f, p, and ϵ; and 0.4% Δk/k for the infinite multiplication factor. The calculation of the effects of flooding on f, p, ϵ, and the infinite multiplication factor agrees with the experiment to within 0.3 to 0.4% Δk/k. When performing the cell calculations, care was taken to determine how to cylinderize the unit cell to perform the one-dimensional calculations with the THERMOS code, how to select the value of the L factor to be used in the JUPITER code (modified MUFT) and how to incorporate the heterogeneous effect of fast fissions.
