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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.
Motoo Fumizawa
Nuclear Technology | Volume 109 | Number 2 | February 1995 | Pages 236-245
Technical Paper | Heat Transfer and Fluid Flow | doi.org/10.13182/NT95-A35056
Articles are hosted by Taylor and Francis Online.
An experimental investigation was carried out for the buoyancy-driven exchange flow in a narrow vertical pipe concerning the air ingress process during a standpipe rupture in a high-temperature gas-cooled reactor. In the current study, the evaluation method of exchange flow was developed by measuring the velocity in the pipe using a laser Doppler velocimeter. The experiments were performed under atmospheric pressure with nitrogen as a working fluid. The Rayleigh numbers range from 2.0 × 104 to 2.1 × 105. The exchange flow fluctuated irregularly with time and space in the pipe. It was found that the exchange-velocity distribution along the horizontal axis changed from one- to two-humped curves with increasing Rayleigh number. In the case that the lower plenum wall was cooler than the heated disk, the volumetric exchange flow rate was smaller than that in the case where the lower plenum wall and heated disk were kept at the same temperature.
