Remote size reduction by hydraulic cutter with buffer device attached to robotic arm using visual support system

Iguchi, Satoshi; Yoshida, Masato; Hirano, Hiroshi*; Wada, Masaomi*; Mori, Yoshihito*; Kitamura, Akihiro

Journal of Robotics and Mechatronics, 37(4), p.973 - 983, 2025/08

https://doi.org/10.20965/jrm.2025.p0973

In nuclear fuel fabrication facilities, gloveboxes are typically dismantled manually. The integration of remotely controlled equipment, comprising a robot arm and a size reduction tool, can enhance work efficiency and mitigate radiation exposure risks in dismantling operations. The hydraulic cutter is regarded as a highly effective tool for reducing the size of steel frame structures, which are commonly composed of gloveboxes. However, when an object is severed by a hydraulic cutter fixed to a robot arm, the resultant reaction force may compromise the integrity of the robot arm or nearby structures. Consequently, in this study, we designed and manufactured a buffer device that can loosely hold the cutter to automatically align the object and absorb the reaction force. Furthermore, a visual support system was developed to assist the operator in performing remote dismantling operations. This system utilized a 3D viewer to project the robot arm, the buffer device, and the working environment. The functionality of the buffer device and 3D viewer was evaluated for the glovebox test bed. The experimental results satisfactorily confirmed the functionality of the buffer device to self-align the object and absorb sudden movements of the hydraulic cutter. Moreover, the 3D viewer provided the robot arm operator with an unobstructed perspective of the work environment, thereby confirming the efficacy of the visual support system in facilitating remote dismantling operations.

Development of plutonium fuel facility decommissioning technology to accelerate glovebox dismantling and reduce air-fed suits based operations

Yoshida, Masato; Iguchi, Satoshi; Hirano, Hiroshi*; Kitamura, Akihiro

Nuclear Engineering and Design, 431, p.113691_1 - 113691_16, 2025/01

https://doi.org/10.1016/j.nucengdes.2024.113691

The Plutonium Fuel Fabrication Facility is currently in the decommissioning phase, with glovebox dismantling operations ongoing since 2010. During conventional glovebox dismantling operations, the glovebox to be dismantled is enclosed within plastic tents to contain contamination. The glovebox is then dismantled by workers wearing air-fed suits with thermal or mechanical cutting tools, which typically generate dross or sparks in the form of radioactive aerosols during cutting. Despite the longevity and meticulous organization of this manual method, the workload remains considerable, while the allowable working time is limited. In addition, the potential for inhalation exposure to plutonium is elevated in the event of an accident given the contamination of the work area. To overcome disadvantages associated with conventional glovebox dismantling methods, new methods are currently being developed. The primary objective is to reduce the reliance on operation based on air-fed suits and enhance worker safety by introducing remote equipment and a new floor-reinforcing panel. Another objective is to suppress waste generation by reusing all equipment on multiple occasions which is achieved by developing a containment system that have a large open port with a pallet for the storage and reuse of equipment for successive operations. Furthermore, a glove operation compartment is designed and tested for the manual handling of dismantled materials as an additional strategy to reduce work based on air-fed suits and mitigate secondary waste generation.

Comparative study of a glovebox dismantling facility for manual and remote glovebox dismantlement activities

Kitamura, Akihiro; Hirano, Hiroshi*; Yoshida, Masato

Nuclear Engineering and Design, 411, p.112435_1 - 112435_14, 2023/09

https://doi.org/10.1016/j.nucengdes.2023.112435

This study presents the features and brief history of the glovebox dismantling facility and the primary dismantlement results. Subsequently, we evaluate the novelties of the facility from operational experiences in manual and remote glovebox dismantlement methods and discuss their characteristics. Furthermore, we evaluate the worker exposure dose based on the obtained data. Finally, we show how these experiences are effectively fed back to the technological dismantlement development for our decommissioning project.

Experiences in dismantlement of gloveboxes for wet recovery and other use that are contaminated with nuclear fuel materials

Kitamura, Akihiro; Hirano, Hiroshi*; Yoshida, Masato; Takeuchi, Kentaro

Hoken Butsuri (Internet), 58(2), p.76 - 90, 2023/08

https://doi.org/10.5453/jhps.58.76

The alpha contaminated gloveboxes have been dismantled for over 20 years in Plutonium Fuel Fabrication Facility. The so called wet recovery equipment gloveboxes, which recover plutonium and uranium from scrap fuel by dissolving and extracting processes, were chosen as the priority gloveboxes to be dismantled. These gloveboxes and other gloveboxes in the same room were size reduced and removed up until 2022. Also, non-radioactive ancillary facility and non-radioactive giant glovebox were removed from 2007 to 2010 for ease of glovebox dismantling activities that follows and for making waste storage spaces. Several incidents were occurred and recidivism prevention measures were implemented on each occasion. In this report, glovebox dismantling activities we conducted in the past 20 years are reviewed and lessons we have learned are summarized.

The Laboratory Operation Based on ISO/IEC 17025; Radioactivity analysis of environmental samples by germanium semiconductor detectors

Urushidate, Tadayuki*; Yoda, Tomoyuki; Otani, Shuichi*; Yamaguchi, Toshio*; Kunii, Nobuaki*; Kuriki, Kazuki*; Fujiwara, Kenso; Niizato, Tadafumi; Kitamura, Akihiro; Iijima, Kazuki

JAEA-Review 2022-023, 8 Pages, 2022/09

JAEA-Review-2022-023.pdf:1.19MB

After the accident of the Fukushima Daiichi Nuclear Power Station, the Japan Atomic Energy Agency has newly set up a laboratory in Fukushima and started measuring radioactivity concentrations of environmental samples. In October 2015, Fukushima Radiation Measurement Group has been accredited the ISO/IEC 17025 standard by the Japan Accreditation Board (JAB) as a testing laboratory for radioactivity analysis (Cs, Cs) based on Gamma-ray spectrometry with germanium semiconductor detectors. The laboratory has measured approximately 60,000 of various environmental samples at the end of March 2022. The laboratory quality control and measurement techniques have been accredited by regular surveillance of JAB. In September 2019, the laboratory renewed accreditation as a testing laboratory for radioactivity analysis.

Low-temperature thermochronology of active arc-arc collision zone, South Fossa Magna region, central Japan

Sueoka, Shigeru; Kobayashi, Yumi*; Fukuda, Shoma; Kohn, B. P.*; Yokoyama, Tatsunori; Sano, Naomi*; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*

Tectonophysics, 828, p.229231_1 - 229231_17, 2022/04

https://doi.org/10.1016/j.tecto.2022.229231

The South Fossa Magna zone, central Japan, has been an active collision zone between the Honshu Arc and the Izu-Bonin Arc since the middle Miocene and provides an excellent setting for reconstructing the earliest stages of continent formation. Multi-system geo-thermochronometry was applied to different domains of the South Fossa Magna zone, together with some previously published data, to reveal mountain formation processes, i.e., vertical crustal movements. Nine granitic samples yielded zircon U-Pb ages of 10.2-5.8 Ma ( = 2), apatite (U-Th)/He (AHe) ages of 42.8-2.6 Ma ( = 7), and apatite fission-track (AFT) ages of 44.1-3.0 Ma ( = 9). Thermal history inversion modeling based on the AHe and AFT data suggested rapid cooling events confined within the study region at 6-2 Ma. The Kanto Mountains may have undergone a domal uplift in association with their collision with the Tanzawa Block at 5 Ma. However, this uplift may have slowed down following the migration of the plate boundary and late Pliocene termination of the Tanzawa collision. The Minobu Mountains and possibly adjacent mountains may have been uplifted by the motional change of the Philippine Sea plate at 3 Ma. Therefore, the mountain formation in the South Fossa Magna zone was mainly controlled by collisions of the Tanzawa and Izu Blocks and motional change of the Philippine Sea plate. Earlier collisions of the Kushigatayama Block at 13 Ma and Misaka Block at 10 Ma appeared to have had little effect on mountain formation. Together with a 90 deg. clockwise rotation of the Kanto Mountains at 12-6 Ma, these observations suggest that horizontal deformation predominated during the earlier stage of arc-arc collision, and vertical movements due to buoyancy resulting from crustal shortening and thickening developed at a later stage.

Rapid analysis of Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometry

Koarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Terashima, Motoki; Fujiwara, Kenso; Kino, Yasushi*; Oka, Toshitaka; Takahashi, Atsushi*; Suzuki, Toshihiko*; et al.

Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08

https://doi.org/10.1039/D1JA00086A

Rapid analysis of Sr in bone and tooth samples of cattle were achieved by an inductively coupled plasma mass spectrometry (ICP-MS) coupled with mass shift and solid phase extraction techniques. Limit of detection (LOD) in the ICP-MS measurement of 0.1 g samples was lower than that of the radioactivity measurement. Analytical time of the ICP-MS method was reduced from 20 days to 11 hours, compared with the radiometric method. Therefore, the ICP-MS method can be rapid and useful procedure of Sr in small bone and tooth samples derived from terrestrial animals.

Applicability of Sr resin for ICP-MS measurement of Sr in hard tissue samples

Koarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Fujiwara, Kenso; Terashima, Motoki; Kitamura, Akihiro; Abe, Hironobu

KEK Proceedings 2020-4, p.180 - 185, 2020/11

https://lib-extopc.kek.jp/preprints/PDF/2020/2025/2025004.pdf

Strontium-90 and Y, its daughter nuclide, adverse effects on the bone marrow. Monitoring of Sr in the bones have been required after the Fukushima-Daiichi Nuclear Power Plant accident. However, conventional radioactivity measurement method for Sr requires a complicated separation of Y and a time-consuming measurement. ICP-MS system has been applied to Sr concentration survey of water, soil, and edible part of fish. We applied the ICP-MS system for the bones for the first time. In this study, reference bone (JSAC 0785 fish bone) was used as measurement samples. Sample preparation of the bone was performed using a microwave digestion instrument. After sample preparation, Sr was determined using ICP-MS system with cascade separation steps based on on-line column separation and oxygen reaction. Strontium-90 in the bones was successfully separated from Ca, Ba, Y, Zr, Fe, Se, and Ge, which interfered in ICP-MS measurement, in the separation steps.

Izu-Bonin arc collision and mountain formation of the South Fossa Magna region; New insight from low-temperature thermochronometry

Kobayashi, Yumi*; Sueoka, Shigeru; Fukuda, Shoma; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*

Fuisshon, Torakku Nyusureta, (33), p.25 - 27, 2020/10

no abstracts in English

Radiocesium distribution in the sediments of the Odaka River estuary, Fukushima, Japan

Hagiwara, Hiroki; Nakanishi, Takahiro; Konishi, Hiromi*; Tsuruta, Tadahiko; Misono, Toshiharu; Fujiwara, Kenso; Kitamura, Akihiro

Journal of Environmental Radioactivity, 220-221, p.106294_1 - 106294_9, 2020/09

https://doi.org/10.1016/j.jenvrad.2020.106294