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Sakasegawa, Hideo; Nomura, Mitsuo; Sawayama, Kengo; Nakayama, Takuya; Yaita, Yumi*; Yonekawa, Hitoshi*; Kobayashi, Noboru*; Arima, Tatsumi*; Hiyama, Toshiaki*; Murata, Eiichi*
Progress in Nuclear Energy, 153, p.104396_1 - 104396_9, 2022/11
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)When dismantling centrifuges in uranium-enrichment facilities, decontamination techniques must be developed to remove uranium-contaminated surfaces of dismantled parts selectively. Dismantled uranium-contaminated parts can be disposed of as nonradioactive wastes or recycled after decontamination appropriate for clearance. previously, we developed a liquid decontamination technique using acidic electrolyzed water to remove uranium-contaminated surfaces. However, further developments are still needed for its actual application. Dismantled parts have various uranium-contaminated surface features due to varied operational conditions, inhomogeneous decontamination using iodine heptafluoride gas, and changes in long-term storage conditions after dismantling. Here, we performed liquid decontamination on specimens with varying uranium-contaminated surfaces cut from a centrifuge made of low-carbon steel. From the results, the liquid decontamination can effectively remove the uranium-contaminated surfaces, and radioactive concentrations fell below the target value within twenty minutes. Although the required time should also depend on dismantled parts' sizes and shapes in their actual application, we demonstrated that it could be an effective decontamination technique for uranium-contaminated steels of dismantled centrifuges.
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.
Magome, Hirokatsu; Okada, Yuji; Tomita, Kenji; Iida, Kazuhiro; Ando, Hitoshi; Yonekawa, Akihisa; Ueda, Haruyasu; Hanawa, Hiroshi; Kanno, Masaru; Sakuta, Yoshiyuki
JAEA-Technology 2015-025, 100 Pages, 2015/09
In Japan Atomic Energy Agency, in order to solve the problem in the long-term operation of a light water reactor, preparation which does the irradiation experiment of light-water reactor fuel and material was advanced. JMTR stopped after the 165th operation cycle in August 2006, and is advancing renewal of the irradiation facility towards re-operation. The material irradiation test facility was installed from 2008 fiscal year to 2012 fiscal year in JMTR. The material irradiation test facility is used for IASCC study, and that consists of mainly three equipments. This report is described performance operating test of the water environmental control facilities for IASCC study carried out 2013 fiscal year.
Magome, Hirokatsu; Okada, Yuji; Hanawa, Hiroshi; Sakuta, Yoshiyuki; Kanno, Masaru; Iida, Kazuhiro; Ando, Hitoshi; Yonekawa, Akihisa; Ueda, Haruyasu; Shibata, Mitsunobu
JAEA-Technology 2014-023, 267 Pages, 2014/07
In Japan Atomic Energy Agency, in order to solve the problem in the long-term operation of a light water reactor, preparation which does the irradiation experiment of light-water reactor fuel and material was advanced. JMTR stopped after the 165th operation cycle in August 2006, and is advancing renewal of the irradiation facility towards re-operation. The material irradiation test facility was installed from 2008 fiscal year to 2012 fiscal year in JMTR. This report summarizes manufacture and installation of the material irradiation test facility for IASCC research carried out from 2012 to 2014 in the follow-up report reported before (JAEA-Technology 2013-019).
Okada, Yuji; Magome, Hirokatsu; Hanawa, Hiroshi; Omi, Masao; Kanno, Masaru; Iida, Kazuhiro; Ando, Hitoshi; Shibata, Mitsunobu; Yonekawa, Akihisa; Ueda, Haruyasu
JAEA-Technology 2013-019, 236 Pages, 2013/10
In Japan Atomic Energy Agency, in order to solve the problem in the long-term operation of a light water reactor, preparation which does the irradiation experiment of light-water reactor fuel and material is advanced. JMTR stopped after the 165th operation cycle in August 2006, and is advancing renewal of the irradiation facility towards re-operation. This material irradiation test facility and power ramping test facility for doing the neutron irradiation test of the fuel and material for light water reactors is scheduled to be manufactured and installed between the 2008 fiscal year and the 2012 fiscal year. This report summarizes manufacture and installation of the material irradiation test facility for IASCC research carried out from the 2008 fiscal year to the 2010 fiscal year.
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