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Ito, Kenji; Kondo, Tetsuo; Nakamura, Yasuyuki; Matsuno, Hiroki; Nagaoki, Yoshihiro; Sakuma, Yuichi
Dekomisshoningu Giho, (63), p.1 - 26, 2022/05
The prototype advanced thermal reactor Fugen entered into the decommissioning phases with the approval of the decommissioning plan in February 2008. The prototype fast breeder reactor Monju entered into the decommissioning stage with the approval of the decommissioning plan in March 2018. In April 2018, the head office of Tsuruga decommissioning demonstration was newly established to oversee the decommissioning operations in Tsuruga area, and decommissioning projects for two unique reactors have progressed safely and steadily.
Takiya, Hiroaki; Kadowaki, Haruhiko; Matsushima, Akira; Matsuo, Hidehiko; Ishiyama, Masahiro; Aratani, Kenta; Tezuka, Masashi
JAEA-Technology 2020-001, 76 Pages, 2020/05
JAEA-Technology-2020-001.pdf:6.06MB
Advanced Thermal Reactor (ATR) FUGEN was operated for about 25 years, and now has been proceeding decommissioning after the approval of the decommissioning plan in Feb. 2008. The reactor, heavy water system and helium system are contaminated by tritium because of neutron absorption of heavy water, which is a moderator. Before dismantling these facilities, it is necessary to remove tritium from them for not only reducing the amount of tritium released to surrounding environment and the risk of internal exposure by tritium but also ensuring the workability. In first phase of decommissioning (Heavy Water and Other system Decontamination Period), tritium decontamination of the reactor, heavy water system and helium system started in 2008 and completed in 2018. This report shows the results of tritium decontamination of the reactor, heavy water system and helium system.
Nakamura, Yasuyuki; Koda, Yuya; Yamamoto, Kosuke; Soejima, Goro; Iguchi, Yukihiro
JAEA-Review 2020-002, 40 Pages, 2020/05
JAEA-Review-2020-002.pdf:8.78MB
Fugen Decommissioning Engineering Center, in planning and carrying out our decommissioning technical development, has been establishing "Technical special committee on Fugen decommissioning" which consists of the members well-informed, aiming to make good use of Fugen as a place for technological development which is opened inside and outside the country, as the central point in the energy research and development base making project of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report compiles presentation materials "The Current Situation of Fugen Decommissioning", "Development of Dismantling Mon-hours Estimated system by Achieved Data in Fugen", "Future Plan Based on the Operational Status of Clearance System" and "The Result and Future Plan of the Sampling work from Core Internal of Fugen", presented in the 37th Technical special committee on Fugen decommissioning which was held on December 2, 2019.
Riyana, E. S.*; Suda, Shoya*; Ishibashi, Kenji*; Matsuura, Hideaki*; Katakura, Junichi*; Sun, G. M.*; Katano, Yoshiaki
Journal of Nuclear Science and Technology, 56(5), p.369 - 375, 2019/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Nuclear reactors produce a great number of electron antineutrinos mainly from beta-decay chains of fission products. Such neutrinos have energies mostly in MeV range. We are interested in neutrinos in a region of keV, since they may have information on fuel burn-up and may be detected in future with advanced measurement technology. We calculate reactor antineutrino spectra especially in the low energy region. In this work we present neutrino spectra from various reactors such as typical PWR reactor and others types of reactors for comparison. Our result shows the electron antineutrino flux in the low energy region increases with burn-up of nuclear fuel by accumulated nuclides with low Q values in beta decay.
Aratani, Kenta; Takiya, Hiroaki; Koda, Yuya; Ishiyama, Masahiro; Tezuka, Masashi; Mizui, Hiroyuki
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 5 Pages, 2019/05
The prototype advanced thermal reactor FUGEN is the heavy water-moderated, boiling light water-cooled, pressure tube-type reactor, and has progressing the decommissioning since 2008. The most of facilities such as turbine system have the system structure and the operating conditions similar to those of BWR, although FUGEN has the characteristic structure of reactor core and the heavy water treatment facilities. In Japan, the knowledge and findings from FUGEN decommissioning activities are very important and valuable to perform BWR decommissioning in future, because the decommissioning of FUGEN is research and development as the first decommissioning of real-scale reactor. In the first phase of FUGEN decommissioning activities, the dismantlement project of reactor core cooling system started. By 2017, the low-level contaminated equipment such as the condensers of turbine system and the main-steam pipes of main-steam system was dismantled, and the management data was accumulated. The knowledge and findings from the 10 years of dismantlement experience will be reflected to the future dismantlement of higher contaminated facilities.
Miki, Naoya*; Harazono, Yuki*; Ishii, Hirotake*; Shimoda, Hiroshi*; Koda, Yuya
International Electronic Journal of Nuclear Safety and Simulation (Internet), 9(2), p.162 - 171, 2018/12
Kyoto University reports on the distance information display system developed in collaboration between "Fugen" and Kyoto University. In the distance information display system, the worker can easily measure the distance of the object. In this presentation, we report the test results carried out with "Fugen" and the questionnaire results of the subjects.
Kadowaki, Haruhiko; Matsushima, Akira; Nakajima, Yoshiaki
Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 6 Pages, 2016/06
Advanced thermal reactor "FUGEN" is a heavy water-moderated boiling light water-cooled pressure tube-type reactor. Because tritium had been generated in the heavy water during the reactor operation, the heavy water system and helium system were contaminated by tritium. The chemical form of the tritium was water molecule in FUGEN. Air-through drying and vacuum drying were applied to the system drying, and it was demonstrated that both methods were effective for drying treatment of heavy water in system. Helium system, low-contamination and non inclusion, could finish the vacuum drying rapidly. However, Heavy water purification system needed long period for drying treatment. The result showed that it needed long period to dry up if the objects include the adsorbent of water such as alumina pellet, resin and silica gel. But it can be accelerated by replacement absorbed heavy water to light water from the result of drying treatment of the rotary type dehumidifier.
Koda, Yuya; Tezuka, Masashi; Yanagihara, Satoshi*
JAEA-Technology 2015-050, 74 Pages, 2016/03
JAEA-Technology-2015-050.pdf:3.43MB
The implementation of the decommissioning work is accompanied by long-term period and considerable expense, so it is important that we make the most optimized work scenario in consideration of safety or the work and effectiveness. For this reason, we are studying selection method of the optimal work scenarios as a management index of the manpower and dose etc., in dismantling work for Fugen. In this report, results of a study shows the method of selecting the best scenarios for the heat exchangers of the reactor coolant purification system by evaluating execution multiple work scenarios, as well as evaluating the manpower and dose, etc., moreover by setting the importance of each evaluation item.
Iwai, Hiroki; Nakamura, Yasuyuki; Mizui, Hiroyuki; Sano, Kazuya
JAEA-Technology 2015-046, 110 Pages, 2016/03
JAEA-Technology-2015-046.pdf:85.22MB
Advanced Thermal Reactor (ATR) FUGEN is a proto-type heavy water moderated, boiling light water cooled, pressure tube-type reactor with the thermal power of 557 MW and the electrical power of 165 MW. The reactor of FUGEN is classified into the core region and the shielding region. The core region is highly activated owing to the long term operation, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel closely. And the shielding region surrounding the core region has the laminated structure composed of up to 150 mm thickness of carbon steel. The reactor is planning to be dismantled under water remotely in order to shield the radiation around the core and prevent airborne dust generated by the cutting, and firing of zirconium material. This paper reports on the result of development of the basic dismantling procedure of the reactor of FUGEN.
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.
Tokai Reprocessing Technology Development Center
JAEA-Evaluation 2015-012, 83 Pages, 2015/12
JAEA-Evaluation-2015-012.pdf:6.67MB
Japan Atomic Energy Agency (hereafter referred as "JAEA") consulted the "Evaluation Committee of Research and Development Activities for Fast Reactor Cycle" to assess the issue on "Research and Development on Reprocessing of Nuclear Fuel Materials" conducted by JAEA during the period from FY2010 to FY2014. In response to the JAEA's request, the committee assessed the R&D programs and the activities of JAEA related to the issue and concluded the mission was accomplished. This evaluation was performed based on the "General guideline for the evaluation of government R&D activities", the "Guideline for evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology (MEXT)" and the "Operational rule for evaluation of R&D activities" by JAEA.
Tsuji, Tomoyuki; Nakamura, Yasuo; Nakatani, Takayoshi
JAEA-Technology 2015-014, 34 Pages, 2015/06
[The article has been found to have a problem about reliability of the corrosion data acquisition, and thus it is unavailable to download the full text in accordance with authors' intentions to retract the report.] In order to dispose of radioactive wastes for sub-surface disposal, JAEA has studied the safety assessment for likely scenario and less-likely scenario. Radioactive nuclide leaching rate under the sub-surface disposal is important parameter in the safety assessment because radioactive nuclides in activated metal wastes are released with its corrosion. In this report, sensitivity of radioactive nuclide leaching rate is studied for the safety assessment. As the result, it is confirmed that Cl-36 which is dominant for the safety assessment in groundwater scenario is sensitive to radioactive nuclide leaching rate, but Nb-94 which is dominant in tunnel excavation scenario is not sensitive to radioactive nuclide leaching rate but to distribution coefficients in engineered barrier.
Hayashi, Hirokazu; Soejima, Goro; Mizui, Hiroyuki; Sano, Kazuya
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05
In the Fugen Nuclear Power Plant, we are going to conduct appropriate classification of the waste according to the contamination level of the material of the plant, to reduce the amount of radioactive waste and to promote dismantling work rationally and efficiently. For this reason, we are going to apply the clearance system to the dismantled material generated from dismantling work of the turbine system, and to reduce the radioactive waste amount as much as possible. In order to operate the clearance system properly, the target nuclides need to be selected accurately, and the evaluation method of them should be established. The assessment was conducted as follows.
Kitamura, Koichi; Kutsuna, Hideki; Matsushima, Akira; Koda, Yuya; Iwai, Hiroki
Dekomisshoningu Giho, (51), p.2 - 10, 2015/04
Fugen Decommissioning Engineering Center (herein after called as "FUGEN") obtained the approval of the decommissioning program on February 2008. FUGEN has been carrying out decommissioning works based on its decommissioning program since then. Now is in initial stage, the dismantling works was launched in turbine system whose contamination was relatively low level and their various data have been accumulating. And the draining heavy water, tritium decontamination and transferring of heavy water were carried out safely and reasonably. The preparation for the clearance system and the research and development works for the reactor core dismantling have been progressed steadily as well. Meanwhile, FUGEN has affiliation with local industries and universities for collaboration research, and has exchanged the decommissioning information with domestic and overseas organizations continuously.
JNC TN1400 2000-012, 250 Pages, 2000/11
JNC-TN1400-2000-012.pdf:10.18MB
no abstracts in English
; ; ; Iguchi, Yukihiro; Matsui, Yuji;
JNC TN3410 2000-014, 43 Pages, 2000/09
JNC-TN3410-2000-014.pdf:2.37MB
None
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JNC TJ3410 2000-021, 73 Pages, 2000/03
JNC-TJ3410-2000-021.pdf:52.78MB
no abstracts in English
*; *; *; *
JNC TJ3410 2000-020, 80 Pages, 2000/03
JNC-TJ3410-2000-020.pdf:41.34MB
no abstracts in English
