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Nakamura, Yasuyuki; Iwai, Hiroki; Mizui, Hiroyuki; Sano, Kazuya
JAEA-Technology 2015-045, 137 Pages, 2016/03
JAEA-Technology-2015-045.pdf:27.77MB
FUGEN is 9 m outer-diameter and 7m height, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel. And the periphery part of the core has the laminated structure composed of up to 150 mm thickness of carbon steel for radiation shielding. The structure of the reactor, which is made of various materials such as stainless steel, carbon steel, zirconium alloy and aluminum. The reactor is planning to be dismantled under water in order to shield the radiation ray around the core and prevent airborne dust generated by the cutting, the temporary pool structure and the remote-operated dismantling machines needs to be installed on the top of reactor. In consideration of above the structure of Fugen reactor, the cutting method was selected for dismantling the reactor core in order to shorten the dismantling term and reduce the secondary waste.
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Dekomisshoningu Giho, 0(14), p.34 - 46, 1996/08
no abstracts in English
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The 3rd JSME/ASME Joint Int. Conf. on Nuclear Engineering (ICONE),Vol. 4, 0, p.1707 - 1710, 1995/00
no abstracts in English
Hoshi, Tatsuo; ; *; *; *; *; *; *
FAPIG, 0(129), p.28 - 32, 1991/11
no abstracts in English
Takiya, Hiroaki; Matsushima, Akira; Ishiyama, Masahiro; Okuzawa, Kazuhiro
no journal, ,
no abstracts in English
Sasagawa, Tsuyoshi; Shimada, Taro; Takeda, Seiji
no journal, ,
In the risk assessment of the decommissioning phase, the inventory of radioactivity accumulated in filters and other materials changes with the progress of dismantling work under normal conditions, and a method that can evaluate the public exposure dose during an accident in which these changes are taken into account is required. The inventories (the mobile radioactive contaminants) include filters in which radioactive dust scattered by equipment cutting work has accumulated and combustible waste generated by decontamination work. In this study, we developed a method to evaluate the accumulation of mobile contaminants in filters by calculating the amount of dust transferred into the air during equipment cutting operations using a model that evaluates the volume of the cutting kerf width and the scattering rate. Furthermore, the amount of the mobile contaminants that accumulates in local filters and building filters for each equipment was evaluated using this method, taking into account differences in cutting methods (underwater or in air) and work processes, and the equipment and work processes that should be focused on during regulatory inspections were studied preliminarily. It was suggested that some components cut in air generate the same amount of the mobile contaminants compared to core structural materials with high radioactivity that are cut in underwater. This indicates that the mobile contaminant is one of the important indicators in nuclear regulatory inspections that influence the selection of inspection targets.
