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Yagi, Naoto; Mita, Yutaka; Kanda, Nobuhiro
Dekomisshoningu Giho, (61), p.2 - 11, 2020/03
Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency has been conducting research and development on uranium exploration, uranium mining, uranium refining / conversion, and uranium enrichment. Currently, our Center has completed its initial mission and is conducting decommissioning of facilities used for R&D, and R&D for decommissioning. Of the three main facilities of our Center, the refining conversion facility and the enrichment engineering facility have already begun dismantling equipment in the facilities. The uranium enrichment demonstration plant is in the process of applying for a decommissioning plan. This report provides an overview of the current status of our Center's decommissioning.
Nakayama, Takuya; Nomura, Mitsuo; Mita, Yutaka; Yonekawa, Hitoshi*; Bunbai, Misako*; Yaita, Yumi*; Murata, Eiichi*; Hosaka, Katsumi*; Sugitsue, Noritake
Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 8 Pages, 2019/05
Clearance of contaminated metal is important for recycling and volume reduction of radioactive waste. Among applicable decontamination technologies, immersion method with ultrasonic cleaning is considered to be effective for metal materials having various shapes. in this study is to demonstrate decontamination of carbon steel contaminated by uranium hexafluoride to the target level for clearance (less than 0.04 Bq/cm), and minimize secondary waste. In this test, acidic electrolytic water, dilute hydrochloric acid, dilute sulfuric acid and ozone water with various pH and redox potential were used as decontamination solutions to be tested. We found that acidic electrolytic water is effective solution for decontamination of carbon steel contaminated by uranium hexafluoride. It could be decontaminate less than target level for clearance, and reduced secondary waste relatively.
Matsumoto, Takashi; Takahashi, Nobuo; Hayashibara, Kenichi; Ishimori, Yuu; Mita, Yutaka; Kakiya, Hideyoshi
JAEA-Technology 2016-020, 80 Pages, 2016/11
The Enrichment Engineering Facility of the Ningyo-toge Environmental Engineering Center was constructed in order to establish the technological basis of plant engineering for uranium enrichment in Japan. Uranium enrichment tests, using natural and reprocessed uranium, were carried out from 1979 to 1989 with two types of centrifuges in the facility. According to the decommissioning plan of the facility, UF handling equipment and supplemental equipment in these plants are intended to be dismantled by 2019 in order to make vacant spaces for future projects use, for example, inventory investigation, precipitation treatment, etc. This report shows the current state of the decommissioning project in the second-half of the fiscal year of 2014.
Kanda, Nobuhiro; Daiten, Masaki; Endo, Yuji; Yoshida, Hideaki; Mita, Yutaka; Naganawa, Hirochika; Nagano, Tetsushi; Yanase, Nobuyuki
JAEA-Technology 2015-007, 43 Pages, 2015/03
The centrifuge which has the subtlety information concerning the nuclear nonproliferation used for uranium enrichment technical development exists in the uranium enrichment facilities of Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency. This centrifugal is performing separation processing of the radioactive material adhering to the surface of parts by wet decontamination of ultrasonic cleaning by dilute sulfuric acid and water, etc. By removing the uranium contained in waste fluid, generated sludge reduces activity concentration. And the possibility of reduction of sludge processing is examined. For this reason, from the 2007 fiscal year, Nuclear Science and Engineering Directorate and cooperation are aimed at, and development of the extraction separation technology of the "uranium" by the emulsion flow method is furthered. The test equipment using the developed emulsion flow method was tested. And dilute sulfuric acid and water were used for the examination as actual waste fluid. The result checked whether the various performances in Basic test carried out in Nuclear Science and Engineering Directorate would be obtained.
Nagano, Tetsushi; Yanase, Nobuyuki; Naganawa, Hirochika; Mitamura, Hisayoshi; Hanzawa, Yukiko; Mita, Yutaka; Kanda, Nobuhiro; Ohashi, Yusuke; Endo, Yuji; Matsubara, Tatsuo
Nihon Genshiryoku Gakkai Wabun Rombunshi, 12(4), p.277 - 285, 2013/12
no abstracts in English
Mitamura, Hisayoshi; Naganawa, Hirochika; Nagano, Tetsushi; Yanase, Nobuyuki; Hanzawa, Yukiko; Shimojo, Kojiro; Matsubara, Tatsuo; Mita, Yutaka; Taki, Tomihiro; Murata, Masato
JAEA-Research 2008-113, 27 Pages, 2009/03
An effective mass processing equipment using solvent extraction method, named "emulsion flow extractor," is the most promising apparatus for removal and recovery of uranium from liquid waste originated from decontamination of uranium-contaminated fluoride waste in the uranium conversion test facility and of used gas centrifuges in the uranium enrichment facility at Ningyo-toge environmental engineering center. Prior to application of the emulsion flow extractor for actual uranium-containing liquid waste, properties of some phosphorous extractants for extraction and separation of uranium and constituents from simulated liquid wastes were examined through batch tests. These preliminary tests revealed that D2EHPA would be a promising candidate for extractant used for treatment of the actual uranium-containing liquid wastes, and that the extractants with a surfactant like AOT would not be useful.
Mita, Yutaka; Matsumura, Toshihiro; Yokoyama, Kaoru; Sugitsue, Noritake
JAEA-Technology 2008-061, 35 Pages, 2008/10
In Ningyo-toge Environmental Engineering Center. The equipments and radioactive waste which were contaminated with uranium are generated so much in future dismantling stage. In our plan, some of equipments and radioactive waste are decontamination to a clearance level, and cut down on decommission and disposal expense. This plan needs the alpha-rays measurement technology of the very low level. We think that ionized Air transfer measurement technology is promising as of clearance verification technology. The ionized Air transfer measurement technology applied to the Ionized Air Type Measurement can measure alpha radioactivity of a very low level. Moreover, as compared with a direct survey, there is the merit which can be measured in a short time. However ionized Air transfer measurement technology is new technology. Therefore, there is almost no measurement track record. Furthermore, the date about the influence of a background, a detection limit, measurement performance, and reliability is insufficient. So, this measurement test estimated applicability as clearance level verification of an Ionized Air Type Measurement.
Annen, Sotonori; Ishimori, Yuu; Ema, Akira; Takanobu, Osamu; Nagayasu, Takaaki; Mita, Yutaka
JNC TN6400 2003-001, 35 Pages, 2003/10
Technology developments for the decommissioning of uranium fuel facilities and the treatments of uranium wastes are one of the current main projects in the Ningyo-toge Environmental Engineering Center of the Japan Nuclear Cycle Development Institute (JNC Ningyo-toge). In order to carry out the project reasonably and safely, all techniques from decommissioning to waste treatment should be unified systematically. Thus, the JNC Ningyo-toge is aiming at the establishment of a 'decommissioning engineering'. This booklet illustrates the decommissioning engineering, especially four engineering elements; that is, a removal technology for uranium compounds, a decommissioning technology of the centrifuges, an application of CaF2 precipitate and a decommissioning engineering system.
Mita, Yutaka
no journal, ,
When we decontaminate and dispose centrifuges of the Ningyo-toge environmental engineering center, by applying the clearance level we utilize resources effectively. As a result we aim at minimizing expenses of abolishing centrifuges. We report on plans of the clearance level of centrifuges and on the measurement.
Mita, Yutaka; Matsumura, Toshihiro; Sugitsue, Noritake; Yamaguchi, Hiromi; Sano, Akira*; Naito, Susumu*; Maekawa, Tatsuyuki*; Yoshimura, Yukio*; Matsumoto, Takashi*
no journal, ,
By using Ionized Air Type Measurement Apparatus which was designed to measure clearance level of dismantled large-scale things which generate from nuclear plants, after chemical decontaminating machinery and materials which are used in plants, we experimented on a real-scale measurement of clearance level of them. We evaluated performance of detection and confirm applicability as a system of measurement of clearance level.
Mita, Yutaka; Sugitsue, Noritake; Ogura, Hiroaki; Daiten, Masaki; Ishimori, Yuu; Ema, Akira
no journal, ,
In enrichment engineering facilities of Ningyo-toge Environmental Engineering Center, make reports on the investment performance that was that there is no need (clearance) dealing with the centrifuge that was contaminated with uranium that was used to technological development of uranium enrichment as radioactive waste. Casings centrifuge was reused metal about 10ton by carrying the decontamination and radioactivity concentration measurement as a flower bed in the center.
Nakayama, Takuya; Nomura, Mitsuo; Mita, Yutaka; Sugitsue, Noritake; Yonekawa, Hitoshi*; Bunbai, Misako*; Yaita, Yumi*; Murata, Eiichi*; Hosaka, Katsumi*
no journal, ,
The metal surface exposed to uranium hexafluoride corrodes covering radioactive materials. We studied reasonably decontamination method. In this test, decontamination characteristics using water, diluted acid, functional electrolyzed water were evaluated using a simulated sample. As a result, we found that the oxidation-reduction potential of functional electrolyzed water affects decontamination performance.
Nakayama, Takuya; Nomura, Mitsuo; Mita, Yutaka; Sugitsue, Noritake; Yonekawa, Hitoshi*; Bunbai, Misako*; Yaita, Yumi*; Murata, Eiichi*; Hosaka, Katsumi*
no journal, ,
For metal exposed to uranium hexafluoride, as a study of a method of reasonably decontaminating radioactive substances attached to a corrosion layer and a base material generated after opening to the atmosphere, removal using a simulated sample and an actual sample Based on the dyeing test results, evaluation of decontamination efficiency, secondary waste generation amount, etc. was carried out. As a result, it was confirmed that acidic functional water decontamination is totally superior to other dilution decontamination.
Nakayama, Takuya; Nomura, Mitsuo; Mita, Yutaka; Sugitsue, Noritake; Yonekawa, Hitoshi*; Bunbai, Misako*; Yaita, Yumi*; Murata, Eiichi*; Hosaka, Katsumi*
no journal, ,
no abstracts in English
中山 卓也; 杉杖 典岳; 美田 豊; 野村 光生
矢板 由美*; 村田 栄一*
【課題】金属母材溶解量を抑制しつつ効率的に除染できる汚染金属の除染方法を提供する。 【解決手段】汚染金属の除染方法は、表面が汚染された金属を、次亜塩素酸を含む酸性電解水で除染することを特徴とする。