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JAEA Reports

Decommissioning report for Wastewater Treatment Facility (Part 2); Chapter on contamination inspection section

Yamamoto, Keisuke; Nakagawa, Takuya; Shimojo, Hiroto; Kijima, Jun; Miura, Daiya; Onose, Yoshihiko*; Namba, Koji*; Uchida, Hiroaki*; Sakamoto, Kazuhiko*; Ono, Chika*; et al.

JAEA-Technology 2024-019, 211 Pages, 2025/02

JAEA-Technology-2024-019.pdf:35.35MB

The uranium enrichment facilities at the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency (JAEA) were constructed sequentially to develop uranium enrichment technology with centrifugal separation method. The developed technologies were transferred to Japan Nuclear Fuel Limited until 2001. And the original purpose has been achieved. Wastewater Treatment Facility, one of the uranium enrichment facilities, was constructed in 1976 to treat radioactive liquid waste generated at the facilities, and it finished the role in 2008. In accordance with the Medium/Long-Term Management Plan of JAEA Facilities, interior equipment installed in this facility had been dismantled and removed since November 2021 to August 2023. This report summarizes the findings obtained through the work related to the contamination inspection methods cancellation the controlled area of Wastewater Treatment Facility from September 2023 to March 2024.

Journal Articles

Proposal of laser-induced ultrasonic guided wave for corrosion detection of reinforced concrete structures in Fukushima Daiichi Nuclear Power Plant decommissioning site

Furusawa, Akinori; Takenaka, Yusuke; Nishimura, Akihiko

Applied Sciences (Internet), 9(17), p.3544_1 - 3544_12, 2019/09

 Times Cited Count:9 Percentile:54.54(Chemistry, Multidisciplinary)

Remote-controlled, non-destructive testing is necessary to detect corrosion of the reinforced concrete structures at the Fukushima Daiichi Nuclear Power Plant (NPP) de-commissioning site. This work aims to demonstrate that laser-induced ultrasonic guided wave technology can be applied to achieve this task. Hence, accelerated electrolytic corrosion is performed on a reinforced concrete specimen fabricated by embedding a steel rod into mortar. Waveforms of the laser-induced ultrasonic guided wave on the rod are measured with a previously employed piezoelectric transducer (PZT) probe, for each fixed corrosion time. Based on the results of Fourier and wavelet transforms of the waveforms, issues concerning the detection and extent of rebar corrosion are discussed. It is exhibited that the changes in bonding strength due to corrosion are distinguishable in the frequency domain of the ultrasonic signal.

Journal Articles

Potential for remote controllable systematization of the method of testing reinforced concrete using guided-wave on rebar

Furusawa, Akinori; Nishimura, Akihiko; Takenaka, Yusuke; Muramatsu, Toshiharu

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

The aim of this work presented here is to demonstrate the potential of our method for remote controllable systematization, of testing reinforced concrete based on ultrasonic guided-wave on rebar. In order to investigate how the deteriorated phenomena has the effects on the ultrasonic guided-wave propagating on the rebar, following experiments are conducted. Test pieces used for the experiments are made of bare steel rod and cylindrically pored mortar to be representing the actual reinforced concrete. Irradiating the end face of the rod with nanosecond pulsed laser makes the ultrasonic guided-wave induced, at the other end face, the guided wave signal is measured with ultrasonic receiver. One test piece is with no damage and the other is deteriorated test piece. The deterioration is made by electrolytic corroded method. The guided-wave signal from the deteriorated test piece is measured with respect to each energization time, the change in the waveform is investigated. Analyzing the results from the experiments above, it is found that the deterioration of rebar has remarkable effects on the guided-wave signal. The signal from test piece with no damage has strong peak at both specific frequency and lower region, on the other hand, signals from deteriorated test piece has only at the specific frequency depending on the diameter of the steel rod. Finally, discussion concerning with the experimental results and future perspective for remote controllable systematization of our method is carried out.

Journal Articles

Development of laser instrumentation devices for inner wall of high temperature piping system

Nishimura, Akihiko; Furusawa, Akinori; Takenaka, Yusuke*

AIP Conference Proceedings 2033, p.080002_1 - 080002_5, 2018/11

 Times Cited Count:1 Percentile:49.29(Green & Sustainable Science & Technology)

We developed a cpmpact laser maintenance device in order to access a 23 mm diameter for heat exchanger tubes of nuclear power plants. A laser instrumentation device was desighned and assembled to measure the corrosion depth at the inlet of heat exchanger tubes. This device can be applied for heat exchanger tubes in CSP where erosion or cracking might be caused by repetitive thermal induced stress.

Journal Articles

Thermal management of heat resistant FBG sensing for high temperature industrial plants

Nishimura, Akihiko; Takenaka, Yusuke*; Furusawa, Akinori; Torimoto, Kazuhiro; Ueda, Masashi; Fukuda, Naoaki*; Hirao, Kazuyuki*

E-Journal of Advanced Maintenance (Internet), 9(2), p.52 - 59, 2017/08

no abstracts in English

Journal Articles

Ultrasonic guided wave approach for inspecting concave surface of the laser butt-welded pipe

Furusawa, Akinori; Nishimura, Akihiko; Takebe, Toshihiko*; Nakamura, Masaki*; Takenaka, Yusuke*; Saijo, Shingo*; Nakamoto, Hiroyuki*

E-Journal of Advanced Maintenance (Internet), 9(2), p.44 - 51, 2017/08

The aim of this work is to investigate the applicability of ultrasonic guided wave for evaluation of laser beam butt-welding quality. Ten in total test pipes having welding seam is prepared. Two piece of pipe are jointed and continuous laser beam is irradiated on the edges, varying laser irradiation power, welding side and surface profile of the adjacent edges of the pipe. Ultrasonic guided wave testing experiment is performed on the pipes. Torsional mode guided wave is excited by EMAT. The experimental results are analyzed and issues are discussed. The reflection wave bullet from the poor interface of the welding seam is clearly observed, whereas no reflection from fine welded line. From the aspect of laser irradiation power, welding side and surface profile of the adjacent edges, the relation between the interface condition and detection wave bullet are analyzed. It is found that the ultrasonic guided wave technologies have the potential for evaluating laser beam butt-welding seam.

Journal Articles

Industry development activities and applied laser research activities at Fukui branch of Japan Atomic Energy Agency

Furusawa, Akinori; Takenaka, Yusuke*; Nishimura, Akihiko; Mizutani, Haruki; Muramatsu, Toshiharu

Nihon Hozen Gakkai Dai-14-Kai Gakujutsu Koenkai Yoshishu, p.479 - 480, 2017/08

Industry development activities on applied laser research held at Fukui branch of Japan Atomic Energy Agency are reported. Industry development is inevitable in long-term vision and strategy for developing maintenance technology and establishing decommissioning technology. Fukui branch of JAEA has organized public seminar offering businesses to promote these activities and technology exchange for years. Here some examples offered in the current seminar are introduced concerning with laser technology. Finally, our goal and important point of view are discussed.

Journal Articles

Development of picosecond laser writing for heat resistant FBG sensors and adhesion technique for high temperature industrial plants

Nishimura, Akihiko; Takenaka, Yusuke*

Sumato Purosesu Gakkai-Shi, 6(2), p.74 - 79, 2017/03

no abstracts in English

Journal Articles

An Approach for remote nondestructive testing method for concrete structure using laser-generated ultrasonic

Furusawa, Akinori; Nishimura, Akihiko; Takenaka, Yusuke*; Nakamura, Kaori*

Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 6 Pages, 2017/00

Testing of concrete structures in NPPs is needed to guarantee hereafter workability. Recent work says Core Concrete Reaction advances erosion of the concrete structures of Fukushima NPPs and it's difficult to estimate the correct depth of CCR. In addition, it is clear that seawater intrusion makes the rebar in the concrete structures corroded, thus, advanced remote testing methods for the deterioration should be considered. Gap or decrease of the adhesiveness between rebar and outer concrete appears in its deterioration process. We had a sense of possibility introducing a new testing method based on that. The concept is to propagate laser-excited ultrasonic gathering the information about the deterioration inside and received at distance with LDV. In this work, we investigate and report how it has the effect on propagating ultrasonic along the rebar to decrease adhesiveness between the rebar and the concrete experimentally.

Journal Articles

Surface modification effects on hydrogen absorption property of a hydrogen storage alloy by short pulse laser irradiation

Abe, Hiroshi; Shimomura, Takuya; Tokuhira, Shinnosuke*; Shimada, Yukihiro*; Takenaka, Yusuke*; Furuyama, Yuta*; Nishimura, Akihiko; Uchida, Hirohisa*; Daido, Hiroyuki; Oshima, Takeshi

Proceedings of 7th International Congress on Laser Advanced Materials Processing (LAMP 2015) (Internet), 4 Pages, 2015/08

A short pulse laser (the nanosecond and femtosecond) was applied to hydrogen absorbing alloys surface layer, and a surface modification experiment was put into effective to aim at improvement of hydrogen adsorption functionally. It was investigated about correlation between an initial hydrogen absorption reaction rate of hydrogen alloys and a laser irradiation in this research. The laser irradiation condition was done with pulse width 100 fsec and energy 0.2 - 3.4 mJ/pulse. It blazed down on hydrogen absorbing alloys (LaNi$$_{4.6}$$Al$$_{0.4}$$) and changed local order in the surface. As a result, the initial hydrogen absorption reaction rate was 1.5 - 3.0 times as fast as a irradiated sample, and the result and laser irradiated sample found out that a hydrogen absorption function improves. A laser irradiation can conclude to be effective in surface modification of the hydrogen storage materials.

Journal Articles

Demonstration of heat resistant fiber Bragg grating sensors based on femtosecond laser processing for vibration monitoring and temperature change

Nishimura, Akihiko; Takenaka, Yusuke*; Furuyama, Takehiro*; Shimomura, Takuya; Terada, Takaya; Daido, Hiroyuki

Journal of Laser Micro/Nanoengineering, 9(3), p.221 - 224, 2014/11

 Times Cited Count:0 Percentile:0.00(Nanoscience & Nanotechnology)

Heat resistant FBG sensors were developed by femtosecond laser processing to apply them to high temperature operated piping system of nuclear power plants. The FBG sensor was installed on the surface of a steel blade and a vibration test was conducted to detect the resonant vibration frequency of the vibrating blade. The FBG sensor had the heatproof performance at 600$$^{circ}$$C. A frequency stabilized sensing system using a tunable laser was tested for structural health monitoring in daily operation of nuclear power plants. The FBG sensor was installed on the surface of a steel blade for vibration induced strain measurements. Welding, brazing, soldering and noble metal powder adhesive were discussed for molding the FBG sensors.

Journal Articles

New instrumentation using a heat resistant FBG sensor installed by laser cladding

Nishimura, Akihiko; Terada, Takaya; Takenaka, Yusuke*; Furuyama, Takehiro*; Shimomura, Takuya

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 6 Pages, 2014/07

Since 2007, JAEA has been developing laser based technologies of structural health monitoring. The FBG sensor made by femtosecond laser processing will be the best candidate. To make the best use of the heat resistant characteristic, the FBG sensor was embedded in metal mold by laser cladding. A groove was processed to the surface of a SUS metal plate. We used a QCW laser to weld a filler wire on the plate. A series of weld beads perfectly formed a sealing clad on the groove. Though the FBG sensor was buried tightly, no degradation on the reflection spectrum was detected after the processing. The FBG sensor could detect the vibration of the plate caused by impact shocks and audio vibration. The reflection peak of the FBG sensor under laser cladding condition was shifted to be 6 nm. We demonstrated that the corresponded temperature derive from the reflection peak shift reached 600 degrees in heat shock experiments. The installation procedure of a FBG sensor using a portable laser cladding machine was described.

Journal Articles

Demonstration of heat resistant Bragg grating by femtosecond laser processing for vibration monitoring

Nishimura, Akihiko; Takenaka, Yusuke*; Furuyama, Takehiro*; Shimomura, Takuya; Terada, Takaya; Daido, Hiroyuki

Proceedings of 1st Smart Laser Processing Conference 2014 (SLPC 2014), 4 Pages, 2014/04

Heat resistant FBG sensors were developed by femtosecond laser processing. In order to apply them to piping system of nuclear power plants, vibration test under high temperature was demonstrated. The FBG sensor had the heatproof performance at 600$$^{circ}$$C. A frequency stabilized sensing system using a tunable laser was tested for structural health monitoring in daily operation of nuclear power plants. The FBG sensor was installed on the surface of a steel blade for vibration induced strain measurements. Welding, brazing, soldering and noble metal powder adhesive were discussed for molding the FBG sensors.

Oral presentation

Study on corrosion inspection of steel bar embedded in concrete using laser excited ultrasonic

Furusawa, Akinori; Nishimura, Akihiko; Takenaka, Yusuke*

no journal, , 

The purpose of this work is to develop ultrasonic methodology of detecting corrosion of the steel bar embedded in concrete. Irradiating pulse-laser beam at the bottom of the corroded steel bar embedded in concrete generates ultrasonic propagating the bar to be measured at another bottom. The corroded steel bar embedded in concrete is made by electrical corrosion method. Comparing waveforms of the corroded steel bar and of the sound one, issues concerning with the different waveforms are reported.

Oral presentation

Application of laser ablation and laser fine processing to atomic energy research

Nishimura, Akihiko; Yamada, Tomonori; Furusawa, Akinori; Takenaka, Yusuke*

no journal, , 

no abstracts in English

Oral presentation

Proposal of in-service monitoring using a deformed steel combined with heat resistant FBG sensors

Nishio, Yuhei*; Nishimura, Akihiko; Takenaka, Yusuke*; Suzuki, Hiroshi; Kanematsu, Manabu*

no journal, , 

no abstracts in English

Oral presentation

Proposal of safety management by optical sensing using heat resistant FBG sensors for thermal energy storage plant

Nishimura, Akihiko; Takenaka, Yusuke; Anoda, Yoshinari

no journal, , 

no abstracts in English

Oral presentation

Towards development of autonomous demolition robot system in decommissioning

Takenaka, Yusuke

no journal, , 

no abstracts in English

Oral presentation

Fabrications of heat resistant FBG sensor and the installation on a sodium circulation loop

Shimomura, Takuya; Nishimura, Akihiko; Terada, Takaya; Takenaka, Yusuke*; Daido, Hiroyuki

no journal, , 

no abstracts in English

Oral presentation

Applicability study of laser beam butt welding for pipe structure maintenance with ultrasonic guided wave

Furusawa, Akinori; Nishimura, Akihiko; Torimoto, Kazuhiro; Takenaka, Yusuke*; Toyama, Ryoji*; Nakamoto, Hiroyuki*

no journal, , 

The aim of this work presented here is to investigate the applicability of ultrasonic guided wave for evaluation of laser beam butt welding quality. First, laser beam butt welded pipes are prepared. Two pipes are jointed and continuous wave laser beam is irradiated on the line. The test pipes are divided into two groups according to the difference in laser welding quality. One group is fine quality welded, another group is poor. Second, ultrasonic guided wave testing experiment is performed on the pipes. Torsional mode guided wave is excited by Electromagnetic Acoustic Transducers. Finally, the experimental results are analyzed and issues are discussed. The reflection wave bullet from the poor welded line is clearly observed, whereas no reflection from fine welded line. It is found that the ultrasonic guided wave technologies have the potential for laser beam butt welding line evaluation.

35 (Records 1-20 displayed on this page)