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Shibanuma, Tomohiro; Hirano, Hiroshi*; Kimura, Yasuhisa; Aita, Takahiro; Yoshida, Masato; Nagai, Yuya; Kitamura, Akihiro
Hoken Butsuri (Internet), 58(2), p.91 - 98, 2023/08
We developed new containment tents that are more easily assembled and effectively functioned, by improving and refurbishing the shortcomings of the conventional tents. The new tents have been already tested in the real airborne contamination situation occurred at the plutonium fuel fabricating facility. The tents appropriately functioned for intended use but other shortcomings emerged and therefore we had modified the structure of the tents further.
Nagai, Yuya; Shuji, Yoshiyuki; Kawasaki, Takeshi; Aita, Takahiro; Kimura, Yasuhisa; Nemoto, Yasunori*; Onuma, Takeshi*; Tomiyama, Noboru*; Hirano, Koji*; Usui, Yasuhiro*; et al.
JAEA-Technology 2022-039, 117 Pages, 2023/06
JAEA-Technology-2022-039.pdf:11.96MB
Japan Atomic Energy Agency (JAEA) manages wide range of nuclear facilities. Many of these facilities are required to be performed adjustment with the aging and complement with the new regulatory standards and the earthquake resistant, since the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Power Station accident. It is therefore desirable to promote decommissioning of facilities that have reached the end of their productive life in order to reduce risk and maintenance costs. However, the progress of facility decommissioning require large amount of money and radioactive waste storage space. In order to address these issues, JAEA has formulated a "The Medium/Long-Term Management Plan of JAEA Facilities" with three pillars: (1) consolidation and prioritization of facilities, (2) assurance of facility safety, and (3) back-end countermeasures. In this plan, Plutonium Fuel Fabrication Facility has been selected as primary decommissioned facility, and dismantling of equipment in the facilities have been underway. In this report, size reduction activities of the glove box W-9 and a part of tunnel F-1, which was connected to W-9, are presented, and the obtained findings are highlighted. The glovebox W-9 had oxidation & reduction furnace, and pellet crushing machine as equipment interior. The duration of activity took six years from February 2014 to February 2020, including suspended period of 4 years due to the enhanced authorization approval process.
Kawasaki, Kohei; Ono, Takanori; Shibanuma, Kimikazu; Goto, Kenta; Aita, Takahiro; Okamoto, Naritoshi; Shinada, Kenta; Ichige, Hidekazu; Takase, Tatsuya; Osaka, Yuki; et al.
JAEA-Technology 2022-031, 91 Pages, 2023/02
JAEA-Technology-2022-031.pdf:6.57MB
The document for back-end policy opened to the public in 2018 by Japan Atomic Energy Agency (hereafter, JAEA) states the decommissioning of facilities of Nuclear Fuel Cycle Engineering Laboratories and JAEA have started gathering up nuclear fuel material of the facilities into Plutonium Fuel Production Facilities (hereafter, PFPF) in order to put it long-term, stable and safe storage. Because we planned to manufacture scrap assemblies almost same with Monju fuel assembly using unsealed plutonium-uranium mixed-oxide (hereafter, MOX) powder held in PFPF and transfer them to storage facilities as part of this "concentration" task of nuclear fuel material, we obtained permission to change the use of nuclear fuel material in response to the new regulatory Requirements in Japan for that. The amount of plutonium (which is neither sintered pellets nor in a lidded powder-transport container) that could be handled in the pellet-manufacturing process was limited to 50 kg Pu or less in order to decrease the facility risk in this manufacture. Therefore, we developed and installed the "MOX weighing and blending equipment" corresponding with small batch sizes that functioned in a starting process and the equipment would decrease handling amounts of plutonium on its downstream processes. The failure data based on our operation and maintenance experiences of MOX fuel production facilities was reflected in the design of the equipment to further improve reliability and maintainability in this development. The completed equipment started its operation using MOX powder in February 2022 and the design has been validated through this half-a-year operation. This report organizes the knowledge obtained through the development of the equipment, the evaluation of the design based on the half-a-year operation results and the issues in future equipment development.
Np and 
Am gamma ray regionsFukuda, Tatsuo; Kobata, Masaaki; Shobu, Takahisa; Yoshii, Kenji; Kamiya, Junichiro; Iwamoto, Yosuke; Makino, Takahiro*; Yamazaki, Yuichi*; Oshima, Takeshi*; Shirai, Yasuhiro*; et al.
Journal of Applied Physics, 132(24), p.245102_1 - 245102_8, 2022/12
Times Cited Count：1 Percentile：6.98(Physics, Applied)Direct energy conversion has been investigated using Ni/SiC Schottky junctions with the irradiation of monochromatized synchrotron X-rays simulating the gamma rays of Np (30 keV) and Am (60 keV). From current-voltage measurements, electrical energies were obtained for both kinds of gamma rays. The energy conversion efficiencies were found to reach up to 
1.6%, which is comparable to those of a few other semiconducting systems reported thus far. This result shows a possibility of energy recovery from nuclear wastes using the present system, judging from the radiation tolerant nature of SiC. Also, we found different conversion efficiencies between the two samples. This could be understandable from hard X-ray photoelectron spectroscopy and secondary ion mass spectroscopy measurements, suggesting the formation of Ni-Si compounds at the interface in the sample with a poor performance. Hence, such combined measurements are useful to provide information that cannot be obtained by electrical measurements alone.
Asakawa, Jun; Hirano, Hiroshi*; Nagai, Yuya; Aita, Takahiro; Shibanuma, Tomohiro; Kimura, Yasuhisa
Hoken Butsuri (Internet), 57(2), p.93 - 101, 2022/09
In the dismantling work of glove boxes (GBs) contaminated with radioactive materials at the nuclear fuel facilities, plastic tents are constructed around the entire GBs, and workers putting on air-fed suits (AFS) (hereinafter referred to as AFS worker) dismantle the GBs and interior equipment by using cutting tools. If an AFS worker suddenly feels sick during the work and the worker is unable to move independently, it will be necessary to exit in the shortest time from the viewpoint of respecting human life. In this case, a lot of radioactive materials may be brought into the contamination control room, thus the room and the equipment of the workers may be contaminated. Consequently, until the decontamination work is completed, the other AFS workers will have to put on AFS and wait for long time, which puts a strain on the workers. In this report, the plastic enclosure tents for body decontamination developed in JAEA were used as a new contamination control room replaced the contaminated one, and the procedure to quickly exit the remaining AFS workers was proposed. As a result, we confirmed that it was possible to greatly reduce the waiting time of the other AFS workers who is forced to wait in the dismantling area.
Shinozaki, Masaru; Aita, Takahiro; Iso, Takahito*; Odakura, Manabu*; Haginoya, Masahiro*; Kadowaki, Hiroyuki*; Kobayashi, Shingo*; Inagawa, Takumu*; Morimoto, Taisei*; Iso, Hidetoshi; et al.
JAEA-Technology 2021-043, 100 Pages, 2022/03
JAEA-Technology-2021-043.pdf:7.49MB
It is planned that the MOX (Mixed Oxide) from the decommissioned facilities in Nuclear Fuel Cycle Engineering Laboratories is going to be consolidated and stored stably and safely for a long term in Plutonium Fuel Production Facility of the Plutonium Fuel Development Center of Nuclear Fuel Cycle Engineering Laboratories. For this purpose, it is necessary to pelletize nuclear fuel materials in the facility and store them in the assembly storage (hereinafter referred to as "waste packaging work") to secure storage space in the plutonium material storage. As a countermeasure to reduce the facility risk in this waste packing work, it was decided to construct a new powder weighing and homogenization mixing facility to physically limit the amount (batch size) of nuclear fuel materials handled at the entrance of the process. In order to secure the installation space for the new facility in the powder preparation room (1) (FP-101), the pre-dismantling temporary waste storage facility 3 (FPG-03a, b, c) was dismantled and removed. This facility consists of a granulating and sizing facility, an additive mixing facility, and a receiving and delivering guided facility, which started to be used from January 1993, and was discontinued on February 3, 2012 and became a waste facility. Subsequently, the dismantling and removal of the interior equipment was carried out by pellet fabrication section for glove operation to reduce the amount of hold-up, and before the main dismantling and removal, there was almost no interior equipment except for large machinery. This report describes the dismantling and removal of the glove box and some interior equipment and peripherals of the facility, as well as the Green House setup method, dismantling and removal procedures, and issues specific to powder process equipment (dust, etc.).
Zr and Mo in concrete rubbleDo, V. K.; Furuse, Takahiro; Murakami, Erina; Aita, Rena; Ota, Yuki; Sato, Soichi
Journal of Radioanalytical and Nuclear Chemistry, 327(1), p.543 - 553, 2021/01
Times Cited Count：6 Percentile：55.57(Chemistry, Analytical)A new HCl-free chromatographic separation procedure has been developed for sequential separation of Zr and Mo from concrete matrices. Accordingly, Zr and Mo could be sensitively and selectively measured by ICP-MS/MS using ammonia reaction gas. The recoveries of greater than 90% for Zr and Mo from concretes could be achieved. The measurement condition was optimized for complete suppression of interferences from Nb and peak tailing from abundant isotopes of Zr and Mo in concrete matrices. The removal of interferences was verified by measurement of radio-contamination-free concretes used as a sample matrix blank. Method detection limits of 1.7 mBq g
and 0.2 Bq g were achieved for Zr and Mo, respectively, in the concrete matrices. The interference removal factor for Nb (equivalent to the decontamination factor in radiochemical separation) was of the order of 10
, and the abundance sensitivity was of the order of 10
, indicating that the developed method is reliable for verifying the presence of ultralow concentrations of Zr and Mo. The present method is suitable for the rapid assessment of Zr and Mo for radioactivity inventory of concrete rubble.
Watanabe, So; Sano, Yuichi; Shiwaku, Hideaki; Yaita, Tsuyoshi; Ono, Shimpei*; Arai, Tsuyoshi*; Matsuura, Haruaki*; Koka, Masashi*; Sato, Takahiro*
Nuclear Instruments and Methods in Physics Research B, 404, p.202 - 206, 2017/08
Times Cited Count：4 Percentile：32.58(Instruments & Instrumentation)平野 宏志; 木村 泰久; 柴沼 智博; 會田 貴洋; 永井 佑哉; 浅川 潤; 吉田 将冬; 周治 愛之
南 明則*
JP, 2019-238397 Patent licensing information Patent publication (In Japanese)
【課題】迅速に組み立て可能な接続テントを提供する。 【解決手段】接続テント(1)は、一対の第1側面フレーム(11、12)及び第1天面フレーム(13)を有する門型フレーム(10)と、第2側面フレーム(21)及び第2天面フレーム(22)を有するL型フレーム(20)と、門型フレーム(10)及びL型フレーム(20)で囲まれた内部空間に収容可能であり、開閉可能な複数の出入口が側面に形成された箱型の部屋テントとを備え、複数の出入口それぞれは、門型フレーム(10)及びL型フレーム(20)の側面に形成された複数の開口のいずれかに対面している。
木村 泰久; 平野 宏志; 柴沼 智博; 吉田 将冬; 永井 佑哉; 塙 幸雄; 周治 愛之; 會田 貴洋
南 明則*
JP, 2020-069715 Patent licensing information Patent publication (In Japanese)
【課題】ポート本体とグローブとを間に隙間が生じるのを適切に防止できるポートキャップを提供する。 【解決手段】ポートキャップ(20)は、取付開口(8)から突出する筒体(16)と、先端部が筒体(16)を通じてグローブボックスの内部空間に進入し、基端部が筒体(16)の外周面側に折り返されたグローブ(12)と、折り返されたグローブ(12)と筒体(16)の外周面との間を封止するOリング(13A,13B)及びクランプリング(14)とを備えるグローブポート(10)に取り付けられ、グローブ(12)の内側から筒体(16)に圧入される内筒(21)と、筒体(16)の外側を覆う外筒(22)と、内筒(21)及び外筒(22)の端部同士を接続するフランジ(23)とを備え、内筒(21)の外周面側の先端(21A)は、R面取りされている。
Do, V. K.; Ota, Yuki; Banjarnahor, I. M.; Aita, Rena; Murakami, Erina; Homma, Shunta; Iwahashi, Hiroyuki; Furuse, Takahiro
no journal, ,
The Okuma Analysis and Research Center has been established to analyze the decommissioning wastes collected from Fukushima Daiichi Nuclear Power Plant (1F). Radioactive material analysis and research facility 1 (Laboratory-1) where analyses of the low and intermediate-level wastes are preliminarily tested has started the operation from October 2022. Among the selected radionuclides to be analyzed, long-lived radionuclides can be measured by inductively coupled plasma mass spectrometry, which offers more rapid measurement and higher sensitivity compared to radiometry. The modern configuration of tandem triple quadrupoles (called ICP-QQQ-MS or ICP-MS/MS) enables the effective control of interferences that can simplify the chemical separation process and thus reduces the total time of analysis. The presentation summarizes our recent advances in research and development of analytical methods for the selected long-lived radionuclides such as Zr, Mo, 
Pd, 
Sn, and 
Se by ICP-MS/MS, aiming at applications to the measurement of samples collected in the vicinity of 1F. The analytical method development and recently obtained results are discussed in detail.
Zr and Mo based on solid phase extraction combined with ICP-MS/MS, 1; Sequential chemical separation of Zr and Mo from NbFuruse, Takahiro; Do, V. K.; Aita, Rena; Ota, Yuki; Murakami, Erina; Tomitsuka, Tomohiro; Sano, Yuichi; Akimoto, Yuji*; Endo, Tsubasa*; Katayama, Atsushi; et al.
no journal, ,
In order to simplify the analysis of Zr and Mo in radioactive waste from conventional radiation measurement, we have considered analysis method combining solid-phase extraction and ICP-MS/MS. In this presentation, we report the results of a study on sequential chemical separation of Zr and Mo from Nb and sample matrix using ZR resin as a solid-phase extraction resin.
Aita, Takahiro; Hirano, Hiroshi*; Kimura, Yasuhisa; Shibanuma, Tomohiro; Yoshida, Masato; Nagai, Yuya; Asakawa, Jun; Shuji, Yoshiyuki
no journal, ,
The newly developed Plastic enclosure tents have reliable airtightness and can be set up in a short time with the small number of persons. Also, in order to prevent the spread of contamination, the exhaust device secures the internal airflow line, and the radiation management device measures the concentration of radioactive materials in the air are in real time. Furthermore, by setting up a multiple of evacuation routes, the decontamination time is shortened even when there are many contaminated persons. Therefore, it is possible to quickly evacuate the contaminated person by having both radiation safety and setting up that can quickly respond to a large-scale body contamination accident.
Zr and Mo based on solid phase extraction combined with ICP-MS/MS, 2; Spectral interference removal for measurement of Zr and Mo by ICP-MS/MSDo, V. K.; Furuse, Takahiro; Murakami, Erina; Aita, Rena; Ota, Yuki; Tomitsuka, Tomohiro; Sano, Yuichi; Akimoto, Yuji*; Endo, Tsubasa*; Katayama, Atsushi; et al.
no journal, ,
The paper presents removal of possible interferences including from an isobar (Nb) and tailings of adjacent peaks for the quantification of Zr and Mo using an ICP-MS/MS (Agilent 8900). By using ammonia gas (NH
) as a reaction gas, Zr and Mo can be separated from each other and from Nb owing to the different reactions of those elements with the reaction gas. Based on the characterization results, we propose a measurement scheme aiming at quantification of Zr and Mo in environmental samples collected at adjacent location of Fukushima Daiichi Nuclear Power Station.
Yoshida, Masato; Kawasaki, Kohei; Aita, Takahiro; Tsubota, Yoichi; Kikuchi, Ryo*; Honda, Fumiya
no journal, ,
no abstracts in English
Yoshii, Kenji; Fukuda, Tatsuo; Tanida, Hajime; Shiwaku, Hideaki; Kamiya, Junichiro; Makino, Takahiro*; Yamazaki, Yuichi*; Oshima, Takeshi*; Yaita, Tsuyoshi
no journal, ,
We have carried out direct energy conversion from gamma rays to electricity using SiC free of toxic elements. The experiments were done using synchrotron radiation at the BL22XU beamline. To utilize radioactive wastes as an energy source, the gamma ray energies were 30 and 60 keV, corresponding to the energies from Np and Am, respectively. Also, CuK
X-rays were used to show a possibility of micro batteries using radioisotopes. The samples were Ni/SiC Schottky barrier junctions. From dark current experiments, it was found that the samples were regarded as ideal diodes on the basis of the so-called ideality factors. The electric powers under gamma rays and X-rays were found to be about 0.1
W, corresponding to efficiencies less than 0.1%. We will also show the results of energy depositions on the basis of Monte Carlo methods.
Yoshida, Masato; Tsubota, Yoichi; Aita, Takahiro
no journal, ,
no abstracts in English
Np and Am gamma ray regions; Interfacial effectFukuda, Tatsuo; Kobata, Masaaki; Shobu, Takahisa; Yoshii, Kenji; Kamiya, Junichiro; Iwamoto, Yosuke; Makino, Takahiro*; Yamazaki, Yuichi*; Oshima, Takeshi*; Shirai, Yasuhiro*; et al.
no journal, ,
no abstracts in English
Asakawa, Jun; Ono, Yosuke; Shibanuma, Tomohiro; Aita, Takahiro; Nagai, Yuya
no journal, ,
no abstracts in English
