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Koda, Yuya; Tezuka, Masashi; Aratani, Kenta; Nanko, Takashi
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05
Decommissioning Engineering Center, which is called FUGEN, has started dismantling works based on its decommissioning program since 2008. The dismantling works was launched in turbine system whose contamination was relatively low level. Feed-water-heaters and main-steam-pipes had been dismantled already, and now, main-condensers have been dismantling. Approximately 1000 tons of dismantled waste was produced from the dismantling works so far. Dismantling work needs to be done safely and effectively with appropriate cutting devices depending on the situations that is its method, quality and shape of the materials to be dismantled. Therefore, in FUGEN, varieties of conventional cutting devices, which are thermal cutting method and mechanical cutting method, are used in the dismantling works to evaluate their applicability depending on the work situations. Obtained cutting data are summarized and evaluated in order to reflect to the following own works and other decommissioning plants.
Kubota, Shintaro; Izumo, Sari; Usui, Hideo; Kawagoshi, Hiroshi; Koda, Yuya; Nanko, Takashi
JAEA-Technology 2014-022, 22 Pages, 2014/07
JAEA-Technology-2014-022.pdf:3.5MB
Japan Atomic Energy Agency (JAEA) has been developing the PRODIA code which supports to make decommissioning plan and has been preparing evaluation functions. Manpower needs for the dismantling the condenser that had conducted from 2010 to 2012 was analyzed and compared with existing evaluation functions. Applicability of evaluation function for a large scale reactor facility was confirmed in dismantling of the heat insulating materials and feed water heaters and reliability of unit productivity factor was improved. Evaluation function of work for clearance was made in dismantling of pipes and supports. Statistically meaningful data was provided from the dismantling of the condenser. Manpower needs for dismantling of a condenser has positive correlation to the weight of equipment and can be described in linear expression. Reliability of each unit productivity factor will be improved with accumulating actual dismantling data in future.
Shibahara, Yuji; Tachibana, Mitsuo; Izumi, Masanori; Nanko, Takashi
JAEA-Technology 2011-010, 44 Pages, 2011/06
JAEA-Technology-2011-010.pdf:2.43MB
Manpower needs for the preparation and clean-up process on the dismantling of equipments in FUGEN 3rd/4th feedwater heater room conducted in 2008 was calculated with the management data evaluation system: PRODIA Code, and it was inspected whether the conventional evaluation model had the applicability for large nuclear facilities such as FUGEN or not. It was confirmed that the conventional evaluation model had no applicability for FUGEN causing by the difference in the plant scale between JPDR and FUGEN bringing the expanding of working area. The difference between the actual data and the calculated value was improved by the reviewing of the evaluation model, and this reviewing process also brought the new evaluation model.
Shibahara, Yuji; Tachibana, Mitsuo; Ishigami, Tsutomu; Izumi, Masanori; Nanko, Takashi
JAEA-Technology 2010-033, 42 Pages, 2010/10
JAEA-Technology-2010-033.pdf:1.02MB
Manpower needs for the dismantling process in FUGEN 3rd/4th feedwater heater room was calculated with the evaluation system (PRODIA Code), and it was inspected whether the conventional evaluation model had applicability for FUGEN or not. It was confirmed that the conventional evaluation model for feedwater heater had no applicability. In comparison of the calculated value with the actual data, we found two difference: (1) the evaluated manpower were significantly larger than the actual data, (2) the manpower need for the dismantling of 3rd feedwater heater was twice larger than that of 4th feedwater heater, though these equipments were almost same weight. It was found that these were brought (1) by the difference in the work descriptions of dismantling between JPDR and FUGEN, and (2) by that in the cutting number between 3rd feedwater heater and 4th one. The manpower needs for the dismantling of both feedwater heaters were calculated with a new calculation equation reflecting the descriptions of dismantling, and it was found that these results showed the good agreement with the actual data.
Shibahara, Yuji; Izumi, Masanori; Nanko, Takashi; Tachibana, Mitsuo; Ishigami, Tsutomu
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.347 - 353, 2010/10
Tezuka, Masashi; Mizui, Hiroyuki; Matsushima, Akira; Nakamura, Yasuyuki; Hayashi, Hirokazu; Sano, Kazuya; Nanko, Takashi; Morishita, Yoshitsugu
Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.2815 - 2821, 2009/09
FUGEN is a proto-type heavy water moderated, boiling light water cooled, pressure tube type reactor with 165MWe and has been shut downed on Mar. 2003. Following the approval of decommissioning program in 2008, stage of FUGEN was changed to the decommissioning of the facilities. The program consists of following four periods; (1) Spent fuel transportation, (2) Periphery facilities dismantlement, (3) Reactor dismantlement and (4) Building demolition. It is expected that the whole decommissioning will be completed until 2028. As a part of the work in the spent fuel transportation period, the main steam system and the feeder water system etc. are being dismantled in the turbine building. The remaining tritium in the heavy water system is also being removed for facilitating the dismantlement of the heavy water system. Moreover, method on dismantlement of the reactor core is being studied with considering the process under the water for the radiation shielding and the dust suppression.
Sano, Kazuya; Noda, Masao; Nanko, Takashi
no journal, ,
no abstracts in English
Izumi, Masanori; Nanko, Takashi; Shibahara, Yuji; Tachibana, Mitsuo; Ishigami, Tsutomu
no journal, ,
The workroad data related the dismantlement of No.3, 4 heater was evaluated and analysised by comparing the actual data and the calculated data.
Shibahara, Yuji; Tachibana, Mitsuo; Ishigami, Tsutomu; Izumi, Masanori; Nanko, Takashi
no journal, ,
no abstracts in English
Shibahara, Yuji; Tachibana, Mitsuo; Izumi, Masanori; Nanko, Takashi
no journal, ,
no abstracts in English
Mizui, Hiroyuki; Hayashi, Hirokazu; Iwai, Hiroki; Imagawa, Yasuhiro; Nanko, Takashi; Sano, Kazuya
no journal, ,
It is the study for evaluating nuclides to be applied to the clearance at FUGEN. The evaluating nuclides was decided to the 10 important nuclides by radioactivity.
