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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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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.
Tomoaki Hino, Takahiro Jinushi, Yuko Hirohata, Masao Hashiba, Yuji Yamauchi, Yutai Katoh, Akira Kohyama
Fusion Science and Technology | Volume 43 | Number 2 | March 2003 | Pages 184-190
Technical Paper | doi.org/10.13182/FST03-A259
Articles are hosted by Taylor and Francis Online.
To employ SiC/SiC composite as blanket components of a fusion reactor, permeation behavior of helium gas has to be investigated since the helium is used as the coolant. For this purpose, a vacuum system consisting of upstream and downstream chambers was fabricated for the measurement of permeability, and the permeability was measured for several SiC/SiC composite materials recently developed. For the pressure range from 102 to 105 Pa in the upstream chamber, the pressure rise due to the permeation of helium in the downstream chamber linearly increased with the pressure of the upstream chamber. Then, the permeability was roughly constant for the pressure range of the upstream chamber.The permeabilities of SiC/SiC composites produced by polymer impregnation and pyrolysis (PIP), hot pressing (HP) and melt-infiltration-finished PIP were 5 × 10-5, 4 × 10-6, and 9 × 10-7 m2/s, respectively. In the matrix structure of the SiC/SiC composite made by the PIP method with a high permeability, cracking in the matrix and pores of micron size were observed. Compared to these materials, SiC/SiC composites produced by liquid phase sintering using submicron or nanopowder of -SiC and the HP method had extremely low permeabilities. The permeability of the SiC/SiC composite made by using submicron or nanopowder of -SiC became 1.5 × 10-9 or 4 × 10-11 m2/s.Based upon the present data, the helium gas flow was analyzed for a blanket module consisting of only SiC/SiC composite. If a vacuum pump is attached to the module, the helium leak into a plasma can be ignored, compared to the heliums produced by fusion reactions. Hence, the entire module can be made by only SiC/SiC composite, from a viewpoint of helium permeation.
