Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 47

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Applicability confirmation experiment of DDSI method for quantification of plutonium in fuel debris

Mitsuboshi, Natsumi; Nagatani, Taketeru; Kosuge, Yoshihiro*; Suzuki, Risa; Okada, Toyofumi

Dai-44-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2023/11

This paper reports the applicability confirmation experiment of DDSI method for quantification of plutonium in fuel debris. We conducted passive neutron measurement for the samples which consist of un-irradiated MOX sample, Cf-252 neutron source, and B-10 neutron absorber to simulate the fuel debris. It was revealed that DDSI method has enough capability to evaluate the leakage multiplication of the sample with unknown amounts of fissile material and neutron absorbers.

Journal Articles

Applicability of differential die-away self-interrogation technique for quantification of spontaneous fission nuclides for fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Nomi, Takayoshi; Okumura, Keisuke

Journal of Nuclear Science and Technology, 60(4), p.460 - 472, 2023/04

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Development of a method for the determination of plutonium in fuel debris by dual times neutron measurements

Nagatani, Taketeru; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Nakaguki, Sho; Nomi, Takayoshi; Okumura, Keisuke

Dai-43-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2022/11

Journal Articles

Preliminary measurement of prompt gamma-ray from nuclear material for the classification of fuel debris and waste

Shiba, Tomooki; Kaburagi, Masaaki; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Nauchi, Yasushi*; Takada, Akira*; Nagatani, Taketeru; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 3 Pages, 2022/10

Journal Articles

Study on identification of materials in fuel debris and waste by neutron induced gamma ray spectroscopy

Nauchi, Yasushi*; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Shiba, Tomooki; Takada, Akira*; Kaburagi, Masaaki; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 4 Pages, 2022/10

Journal Articles

Characterization study of four candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station

Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Nauchi, Yasushi*; Maeda, Makoto; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; et al.

Energy Procedia, 131, p.258 - 263, 2017/12

 Times Cited Count:8 Percentile:98.51

Journal Articles

Applicability evaluation of candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station; Passive neutron technique (Interim report)

Nagatani, Taketeru; Kosuge, Yoshihiro*; Shirato, Atsuhiko*; Sato, Takashi*; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 57th Annual Meeting (Internet), 10 Pages, 2016/07

Journal Articles

Characterization study of four candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station (Interim report)

Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Maeda, Makoto; Nauchi, Yasushi*; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; et al.

Proceedings of INMM 57th Annual Meeting (Internet), 10 Pages, 2016/07

Journal Articles

Experimental studies of passive neutron measurement for fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Shirato, Atsuhiko*; Kosuge, Yoshihiro*; Sato, Takashi*; Kawakubo, Yoko; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 56th Annual Meeting (Internet), 10 Pages, 2015/07

As one of the candidate material accountancy technologies for the fuel debris at Fukushima Daiichi Nuclear Power Plants (1F), we propose the application of a passive neutron technique. The applicability of the new concept to the fuel debris at 1F was evaluated by simulation and the results were presented at the last INMM annual meeting. As the next phase, we conducted experimental tests to confirm the validity of the simulation results. Because actual fuel debris or irradiated fuel cannot be handled at our facility due to a licensing limitation, un-irradiated MOX samples, neutron absorbers and Cf-252 sources were utilized as the best available material to imitate the property of the fuel debris and various configurations were measured using an Epithermal Neutron Multiplicity Counter. The fissile mass in the samples, neutron absorber mass surrounding the samples and intensity of Cf-252 source were varied to confirm the correlation between DDSI response and the leakage multiplication. Test results agreed well with the trend of the simulation results. This indicates that DDSI has sufficient capability to evaluate the leakage multiplication of a sample which includes an unknown amount of fissile material and neutron absorber such as the fuel debris at 1F. This paper provides experimental studies of passive neutron measurement based on the combination of DDSI technique and coincidence counting for fuel debris at 1F.

Journal Articles

Current status of the driver laser system for intense terahertz wave generation

Tanaka, Momoko; Ochi, Yoshihiro; Kosuge, Atsushi; Okada, Hajime; Mori, Michiaki; Kiriyama, Hiromitsu; Tsubouchi, Masaaki; Nagashima, Keisuke

JAEA-Conf 2014-001, p.32 - 33, 2014/09

We have constructed a high power kHz laser system using Yb:YAG thin-disk as a gain medium for a driver laser of THz wave generation. A 4-bounce regenerative amplifier is constructed and output energy up to 10 mJ is obtained. Using compressed pulse, we demonstrated THz wave generation with LiNbO$$_{3}$$ crystal.

Journal Articles

Monte Carlo N-Particle eXtended (MCNPX) simulation for passive neutron measurement of fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Nakajima, Shinji; Kosuge, Yoshihiro*; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 55th Annual Meeting (Internet), 10 Pages, 2014/07

Meltdown of the reactor cores of Units 1-3 occurred at Fukushima Daiichi Nuclear Power Plants (1F). Fuel debris at 1F contains minor actinides and fission products and neutron absorber. These materials make it difficult to quantify fertile nuclear materials in fuel debris by the conventional passive neutron technique. We consider that DDSI and PNAR which focused on fissile material are promising techniques to quantify the nuclear materials in the fuel debris. A concept of application of these techniques to fuel debris measurement was investigated and presented at the last INMM annual meeting. In order to evaluate the applicability of these techniques to fuel debris measurement, we investigated the neutron behavior in the fuel debris by using MCNPX simulation code. Because property of fuel debris is not clear, source term data used were prepared by referring TMI data. This paper provides results of MCNPX simulation for fuel debris measurement at 1F with passive neutron techniques.

Journal Articles

High power laser developments with femtosecond to nanosecond pulse durations for laser shock science and engineering

Kiriyama, Hiromitsu; Mori, Michiaki; Suzuki, Masayuki*; Daito, Izuru*; Okada, Hajime; Ochi, Yoshihiro; Tanaka, Momoko; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; et al.

Reza Kenkyu, 42(6), p.441 - 447, 2014/06

We describe three specific high power laser systems that are being developed in our laboratory for many applications in high field science, nonlinear optics and material processing. We report on a femtosecond petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 20 J of 40 fs pulse duration, a picosecond high intensity Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 mJ of 0.5 ps pulse duration, and a nanosecond high repetition rate Nd:YAG laser system that can provide an average power of 360 W with a pulse duration of 30 ns delivered at a 1 kHz repetition rate. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.

Journal Articles

Improvement of diffraction efficiency of dielectric transmission gratings using anti-reflection coatings

Nagashima, Keisuke; Kosuge, Atsushi; Ochi, Yoshihiro; Tanaka, Momoko

Optics Express (Internet), 21(16), p.18640 - 18645, 2013/07

 Times Cited Count:14 Percentile:59.77(Optics)

A novel method for increasing diffraction efficiency of transmission gratings is proposed. In this method, dielectric multilayers are inserted between a grating region and a substrate. These multilayers work as an anti-reflection coating for the transmission grating. It is presented that a grating with 1740 grooves/mm has the diffraction efficiency over 99% using this anti-reflection coating.

Journal Articles

Laser R&D project in this 5-year term

Sugiyama, Akira; Kiriyama, Hiromitsu; Ochi, Yoshihiro; Mori, Michiaki; Tanaka, Momoko; Sasao, Fumitaka; Kosuge, Atsushi; Okada, Hajime

JAEA-Conf 2011-001, p.15 - 18, 2011/03

Main theme of our group in this middle term JAEA program is a development of high-averaged power short pulse laser system pumped by LDs (laser diodes). To realize this next term laser system, we have just started considering a Yb doped ceramics laser with a several members of KPSI. We have also developed a laser system named QUADRA (high-Quality Ultra ADvanced RAdiation Sources) in C-Phost program. In the first term up to FYH22, essential studies for QUADRA have been investigated. In the second term, QUADRA development will be merged with the next term laser system in JAEA to produce high powered THz radiation. In addition to these developments, we support to improve the performances of conventional high-power laser system, J-KAREN, for the requirement of advanced application studies in this middle term JAEA program.

Journal Articles

Development of a high-contrast, high beam-quality, high-intensity laser

Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime*; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Kondo, Shuji; Kanazawa, Shuhei; et al.

Reza Kenkyu, 38(9), p.669 - 675, 2010/09

This paper reviews the temporal contrast and spatial beam quality improvement techniques in a high intensity Ti:sapphire laser system that is based on chirped-pulse amplification (CPA). We describe a low gain optical parametric chirped-pulse amplification (OPCPA) preamplifier that uses high energy, clean pulse seeding and is shown to significantly improve the contrast to better than 10$$^{-10}$$-10$$^{-11}$$ relative to the peak of the main femtosecond pulse. We also report the use of a diffractive optical element for beam homogenization of a 100 J level Nd:glass green pump laser, achieving a flat-topped spatial profile with a filling factor near 80 %.

Journal Articles

Demonstration of a high-efficiency, broadband optical parametric chirped-pulse amplification as a front-end for a high intensity laser

Kosuge, Atsushi; Kiriyama, Hiromitsu; Shimomura, Takuya*; Tanoue, Manabu*; Kanazawa, Shuhei; Ochi, Yoshihiro; Mori, Michiaki; Tanaka, Momoko; Okada, Hajime; Sasao, Hajime*; et al.

Reza Kenkyu, 38(9), p.706 - 710, 2010/09

High conversion efficiency of optical parametric chirped-pulse amplification (OPCPA) is demonstrated with the use of a commercial frequency-doubled Q-Switched Nd:YAG laser. In the high energy seeded OPCPA, we have achieved a pump-to-signal conversion efficiency of 28%. Our result represents, to our knowledge, the most efficient OPCPA to date pumped by a commercial frequency-doubled Q-switched Nd:YAG laser.

Oral presentation

Annual progress and future plans of Laser R&D Group

Sugiyama, Akira; Kiriyama, Hiromitsu; Ochi, Yoshihiro; Tanaka, Momoko; Nakai, Yoshiki; Sasao, Hajime; Tateno, Ryo; Okada, Hajime; Kosuge, Atsushi; Tsubouchi, Masaaki

no journal, , 

The main subject of our group is upgrade of J-KAREN and TOPAZ laser systems. The J-KAREN achieves the potential for generating a peak power of 500 TW, and exceeds a contrast ratio of 10E10. The TOPAZ achieves pulse power of 15 J at a repetition rate of 0.1 Hz. We also started a development of another laser system named QUADRA (Quality Ultra ADvanced RAdiation Source) in C-Phost. The QUADRA system is a high averaged short pulse laser pumped by high power LD at kHz repetition rate. This development is essential for the developments of other new laser systems in the next 5-year program of JAEA.

Oral presentation

Demonstration of a high spatiotempral-quality petawatt-class Ti:sapphire CPA laser system

Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime*; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kanazawa, Shuhei; et al.

no journal, , 

OPCPA (Optical parametric chirped-pulse amplification) operation with low gain by seeding with high energy, clean pulses is shown to significantly improve the contrast to better than 10$$^{-10}$$-10$$^{-11}$$ in a high intensity Ti:sapphire laser system that is based on chirped pulse amplification. In addition to the high contrast broadband high energy output from the final amplifier is achieved with a flat-topped spatial profile of filling factor near 77 %. This is the result of pump beam spatial profile homogenization with diffractive optical elements. Final pulse energies exceed 30 Joules indicating capability for reaching peak powers in excess of 500-TW.

Oral presentation

Demonstration of a high-efficiency, broadband optical parametric chirped-pulse amplification as a front-end for a high intensity laser

Kosuge, Atsushi; Kiriyama, Hiromitsu; Shimomura, Takuya; Tanoue, Manabu*; Kanazawa, Shuhei; Ochi, Yoshihiro; Mori, Michiaki; Tanaka, Momoko; Okada, Hajime; Sasao, Hajime*; et al.

no journal, , 

High conversion efficiency of optical parametric chirped-pulse amplification (OPCPA) is demonstrated with the use of a commercial frequency-doubled Q-Switched Nd:YAG laser. In the high energy seeded OPCPA, we have achieved a pump-to-signal conversion efficiency of 28%. Our result represents, to our knowledge, the most efficient OPCPA to date pumped by a commercial frequency-doubled Q-switched Nd:YAG laser.

Oral presentation

Peta watt class laser in Japan

Kiriyama, Hiromitsu; Nagashima, Keisuke; Ochi, Yoshihiro; Mori, Michiaki; Tanaka, Momoko; Sasao, Fumitaka; Kosuge, Atsushi; Okada, Hajime; Kondo, Kiminori; Sagisaka, Akito; et al.

no journal, , 

We have developed a femtosecond high intensity laser system, which combines both Ti:sapphire chirped-pulse amplification (CPA) and optical parametric chirped-pulse amplification (OPCPA) techniques, that produces more than 30 J broadband output energy, indicating the potential for achieving peak powers in excess of 500 TW. With a cleaned high-energy seeded OPCPA preamplifier as a front-end in the system, for the final compressed pulse we found that the temporal contrast in this system exceeds 10$$^{10}$$ on the sub-nanosecond timescale before the main femtosecond pulse. Using diffractive optical elements for beam homogenization of 100-J level high-energy Nd:glass green pump laser in a Ti:sapphire final amplifier, we have successfully generated broadband high-energy output with near-perfect top-hat intensity distributions.

47 (Records 1-20 displayed on this page)