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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. J. Rush, D. W. Connor, and R. S. Carter
Nuclear Science and Engineering | Volume 25 | Number 4 | August 1966 | Pages 383-389
Technical Paper | doi.org/10.13182/NSE66-A18558
Articles are hosted by Taylor and Francis Online.
The leakage flux from an 18 × 18 in. cylinder of D2O with a beam of pile neutrons incident at its center has been studied at D2O temperatures from 22° to 293°K. Intensities through beryllium and graphite filters, as well as indium foil transmissions, have been measured to determine cold-neutron fractions and neutron temperatures for the emerging spectra. The results of these measurements show that large volumes of D2O ice can be useful as low-temperature moderators in reactors. The percentage of leakage neutrons with λn ≥ 3.95 Å is 21% at 22°K, a 20-fold increase over the fraction at 293°K, and about twice the value at 100°K. The neutron temperature of the leakage spectrum, calculated from the transmission data assuming a Maxwellian distribution, decreases with moderator temperature, reaching a value of about 75° for D2O at 22°K. An abrupt increase in the fraction of cold neutrons is observed at the D2O freezing point, which appears to reflect a change in the transport rather than the moderating properties of the D2O, due to a decrease in the cross section for long-wavelength neutrons.
