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Journal Articles

Oxidation characteristics of lead-alloy coolants in air ingress accident

Kondo, Masatoshi*; Okubo, Nariaki; Irisawa, Eriko; Komatsu, Atsushi; Ishikawa, Norito; Tanaka, Teruya*

Energy Procedia, 131, p.386 - 394, 2017/12

 Times Cited Count:4 Percentile:95.35

The chemical behaviors of lead (Pb) based coolants in the air ingress accident of fast reactors were investigated by means of the thermodynamic considerations and the static oxidation experiments for Pb alloys at various chemical compositions. The results of the static oxidation tests for lead-bismuth (Pb-Bi) alloys indicated that Pb was depleted from the alloy due to the preferential formation of PbO in air at 773K. Pb-Bi oxide and Bi$$_{2}$$O$$_{3}$$ were formed after the enrichment of Bi in the alloys due to the Pb depletion. The oxidation rates of the alloys were much larger than that of the steels, and became larger with higher Pb concentration in the alloys. The compatibility of Pb-Bi alloys with stainless steel was worse when the Pb concentration in the alloys became low, since the dissolution type corrosion was promoted by the Bi composition in the alloy. The Pb-Li alloys were oxidized as they formed Li$$_{2}$$PbO$$_{3}$$ and Li$$_{2}$$CO$$_{3}$$. Then, Li was depleted from the alloy.

Journal Articles

Electrochemical impedance analysis on solid electrolyte oxygen sensor with gas and liquid reference electrodes for liquid LBE

Adhi, P. M.*; Okubo, Nariaki; Komatsu, Atsushi; Kondo, Masatoshi*; Takahashi, Minoru*

Energy Procedia, 131, p.420 - 427, 2017/12

 Times Cited Count:0 Percentile:0.03

The ionic conductivity of solid electrolyte may insufficient, and the sensor output signal will deviate from the theoretical one in low temperature. The performance of oxygen sensor with Ag/air reference electrode (RE) and liquid Bi/Bi$$_{2}$$O$$_{3}$$ RE was tested in low-temperature LBE at 300$$sim$$450$$^{circ}$$C and the charge transfer reactions impedance at the electrode-electrolyte interface was analyzed by electrochemical impedance analysis (EIS). After steady state condition, both of the sensors performed well and can be used at 300$$sim$$450$$^{circ}$$C. Bi/Bi/Bi$$_{2}$$O$$_{3}$$ RE has lower impedance than Ag/air RE. Therefore, the response time of the oxygen sensor with Bi/Bi/Bi$$_{2}$$O$$_{3}$$ RE is faster than the oxygen sensor with Ag/air RE in the low-temperature region.

Journal Articles

Waste management scenario in the hot cell and waste storage for DEMO

Someya, Yoji; Tobita, Kenji; Yanagihara, Satoshi*; Kondo, Masatoshi*; Uto, Hiroyasu; Asakura, Nobuyuki; Hoshino, Kazuo; Nakamura, Makoto; Sakamoto, Yoshiteru

Fusion Engineering and Design, 89(9-10), p.2033 - 2037, 2014/10

 Times Cited Count:6 Percentile:50.1(Nuclear Science & Technology)

In the replacement period of a fusion power reactor, the assembly of blanket or divertor modules need to be removed from the reactor in order to minimize remote maintenance in the vacuum vessel and to attain a reasonable plant availability. In the hot cell, the modules will be removed from the backplate of the assembly. Here, note that the active cooling must be done by a way that does not cause contamination of the hot cell environment due to dispersion of tritium and tungsten dust. In this sense, the cooling scenario is adopted that the existing pipe of cooling water in the assembly is connected to a different cooling water system in the hot cell. In this scenario, the temperature of the assembly is maintained about 40-100$$^{circ}$$C. On the other hand, the structural material (RAFM) of the blanket and divertor is not recycled due to its high contact dose rate. It should be crushed into small pieces to reduce volume of the waste and required storage space. Here, the decay heat must be removed by natural convection to keep the temperature below 65$$^{circ}$$C for preventing water evaporation from the mortar. The RAFM is kept in the interim storage during 12 years until the required temperature conditions for mortar are ensured and then is disposed of.

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

High intensity, high temporal contrast, high repetition-rate laser for laser driven particle acceleration

Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Yoshii, Takehiro*; Tamaoki, Yoshinori*; Maeda, Junya*; Matsuoka, Shinichi*; et al.

AIP Conference Proceedings 1465, p.53 - 57, 2012/07

 Times Cited Count:0 Percentile:0.13

We have reported hundred mJ level, femtosecond pulse duration with the high temporal contrast in an OPCPA/Yb:YAG ceramic thin disk laser system at 10 Hz repetition rate. At an input laser pulse energy of 3.8 mJ from the OPCPA preamplifer the output energy of 130 mJ with spectral bandwidth of 2.5 nm has been obtained from multipass Yb:YAG ceramic thin disk amplifier, and the optical efficiency from LD energy to amplified laser pulse is 9.6%. The recompressed laser pulse duration was measured to be 450 fs. Because the compressor efficiency exceeds 73% the compressed pulse energy can potentially be as high as 95 mJ. The contrast level of this laser pulse was measured to be less than 7.2$$times$$10$$^{-9}$$ at -150 ps. This novel laser system after further amplification using additional amplifiers can be useful for the laser-driven proton acceleration in future.

Journal Articles

Development of a compact high-spatiotemporal-quality Yb:YAG thin-disk laser system using an optical parametric preamplifier

Kiriyama, Hiromitsu; Suzuki, Masayuki*; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; Matsuoka, Shinichi*; et al.

Reza Kenkyu, 40(2), p.143 - 145, 2012/02

We demonstrate a compact, high-spatiotemporal-quality, high-intensity diode-pumped Yb:YAG thin-disk chirped-pulse amplification (CPA) laser system that incorporates a nonlinear preamplifier based on optical parametric chirped-pulse amplification (OPCPA). The stretched pulses are amplified in the OPCPA preamplifier and the following Yb:YAG main amplifier to $$sim$$100 mJ at 10 Hz. The broadband amplified beam quality of 1.1 (horizontal direction) and 1.4 (vertical direction) times diffraction limited and pulse compression down to 470 fs with contrast of better than 10$$^{-8}$$ have been achieved successfully.

Journal Articles

Hundred mJ, sub-picoseconds, high temporal contrast OPCPA/Yb:YAG ceramic thin disk hybrid laser system

Suzuki, Masayuki*; Kiriyama, Hiromitsu; Daito, Izuru; Ochi, Yoshihiro; Okada, Hajime; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; Matsuoka, Shinichi*; et al.

Applied Physics B, 105(2), p.181 - 184, 2011/11

 Times Cited Count:4 Percentile:26.01(Optics)

We have demonstrated an OPCPA/Yb:YAG ceramic thin disk hybrid laser system having hundred mJ level pulse energy sub-picosecond pulse duration with high temporal contrast. At an input energy of 3.8 mJ from an OPCPA preamplifier an output energy of 130 mJ was obtained from Yb:YAG ceramic thin disk amplifier. A recompressed pulse duration of 450 fs with a contrast level of less than 7.2$$times$$10$$^-9$$ was obtained. The contrast level is the highest value achieved in Yb:YAG chirped pulse amplification (CPA) laser system with hundred mJ level.

Journal Articles

Development of Ultrasonic Flow Meter for Liquid Lead-Bismuth Flow

Hirabayashi, Masaru; Kondo, Masatoshi*; Ara, Kuniaki; Takahashi, Minoru*

Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13) (CD-ROM), 0 Pages, 2005/05

In Pb-Bi Cooled Direct Contact Boiling Water Small Fast Reactor, PBWFR, a development of a primary loop flow meter is required. Since an electromagnetic flow meter is not better suited to an annular channel geometry such as the primary loop of PBWFR, an ultrasonic flow meter to measure the velocity of Pb-Bi has been developed.An ultrasonic transit-time method is applied to the flow velocity measurement. To evaluate the flow velocity in this method, the sound velocity in Pb-Bi is required. Therefore the sound velocity in Pb-Bi was measured at the temperature range from 187 to 407$$^{circ}$$C and the experimental correlation equation of the sound velocity was derived. An ultrasonic flow meter which consisted of the high-temperature sensors and the signal processor was developed and manufactured on trial. The piezoelectric element of the sensor was lithium niobate. The sensor was heated up to 500oC and the heat resistance was confirmed. The shoe, i.e. the material wetted by Pb-Bi, of the sensor was made from high-chrome steel. The in-water and the in-Pb-Bi tests were performed and the applicability of the ultrasonic flow meter was verified.

JAEA Reports

Basic research on proton acceleration based on lasers and plasmas, JAERI's nuclear research promotion program, H10-008 (Contract research)

Ogata, Atsushi*; Okamoto, Hiromi*; Kusano, Kanya*; Endo, Ichita*; Nishida, Yasushi*; Sakae, Takeji*; Arai, Masatoshi*; Nakanishi, Hiroshi*; Kondo, Kiminori*

JAERI-Tech 2002-007, 28 Pages, 2002/03

JAERI-Tech-2002-007.pdf:1.34MB

no abstracts in English

Oral presentation

High intensity, high contrast OPCPA/Yb:YAG hybrid laser system

Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Nakai, Yoshiki*; Daido, Hiroyuki; Bolton, P.; Sugiyama, Akira; Kondo, Kiminori; Kawanishi, Shunichi; et al.

no journal, , 

At our Institute we are developing a compact ion accelerator for cancer therapy using a laser-driven plasma point source of ions. The laser system was consisted of an oscillator, offner stretcher, optical parametric amplifier (OPCPA), LD pumped Yb:YAG amplifier, and compressor. In OPCPA the stretched laser pulse after the pulse stretcher was amplified to 5 mJ with only a 0.2 mJ input. After amplification in the OPCPA laser pulse was further amplified by an Yb:YAG (5 at%) thin disk module which was pumped by the Q-CW LD. The maximum output energy was about 120 mJ in a multi-pass scheme (20 pass) at 10 Hz. The compressed pulse duration is about 300 fs, and the contrast level before the main pulse is measured as 10$$^{-8}$$ at -150 ps. We have developed that new high intensity, high contrast femtosecond OPCPA/LD-pumped Yb:YAG hybrid laser system. This novel system might represent the driver in integrated, laser-driven ion accelerator systems.

Oral presentation

OPCPA/LD pumped Yb:YAG thin disk hybrid laser system

Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Sato, Masatoshi*; Yoshii, Takehiro*; Tamaoki, Yoshinori*; Matsuoka, Shinichi*; Kan, Hirofumi*; Bolton, P.; et al.

no journal, , 

no abstracts in English

Oral presentation

Hundred mJ level, high contrast OPCPA/Yb:YAG hybrid laser system

Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Bolton, P.; Sugiyama, Akira; Kondo, Kiminori; Kawanishi, Shunichi*; Sato, Masatoshi*; Tamaoki, Yoshinori*; et al.

no journal, , 

At our Institute we are developing a compact ion accelerator for cancer therapy using a laser-driven plasma point source of ions. The laser system was consisted of an oscillator, Offner stretcher, optical parametric amplifier (OPCPA), LD pumped Yb:YAG amplifier, and compressor. In OPCPA the stretched laser pulse after the pulse stretcher was amplified to 3.8 mJ with only a 12.8 nJ input. After amplification in the OPCPA laser pulse was further amplified by an Yb:YAG thin disk module which was pumped by the Q-CW LD. The maximum output energy was about 80 mJ in a multi-pass scheme (20 pass) at 10 Hz. The compressed pulse duration is about 520 fs, and the contrast level before the main pulse is measured as 10$$^{-8}$$ at -150 ps. We have developed that new high intensity, high contrast femtosecond OPCPA/LD-pumped Yb:YAG hybrid laser system. This novel system might represent the driver in integrated, laser-driven ion accelerator systems.

Oral presentation

High-spatiotemporal-quality high-intensity laser system

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

no journal, , 

We report on a femtosecond high-intensity OPCPA/Ti:sapphire hybrid laser system that produces more than 30 J broadband output energy, indicating the potential for achieving petawatt-class peak powers. High temporal-contrast of 10$$^{-10}$$ to 10$$^{-11}$$ has been obtained with a near-perfect flat-topped spatial-profile of filling factor $$sim$$80%. We also present a compact, high-intensity OPCPA/Yb:YAG hybrid laser system that generates $$sim$$100 mJ output energy with a temporal contrast of better than 10$$^{-8}$$ and good spatial beam quality.

Oral presentation

Generation of low noise sub-picosecond laser pulses for investigating laser peening

Suzuki, Masayuki*; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Yoshii, Takehiro*; Tamaoki, Yoshinori*; Maeda, Junya*; Matsuoka, Shinichi*; et al.

no journal, , 

no abstracts in English

Oral presentation

Hundred mJ level OPCPA/Yb:YAG ceramic thin disk hybrid laser system

Suzuki, Masayuki*; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Yoshii, Takehiro*; Tamaoki, Yoshinori*; Maeda, Junya*; Matsuoka, Shinichi*; et al.

no journal, , 

no abstracts in English

Oral presentation

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

Kiriyama, Hiromitsu; Mori, Michiaki; Shimomura, Takuya; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Daito, Izuru; Suzuki, Masayuki*; Okada, Hajime; Ochi, Yoshihiro; et al.

no journal, , 

We describe two specific high intensity laser systems that are being developed in our laboratory for many applications such as high field science, nonlinear optics. We report on an ultra-high intensity petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of $$sim$$ 18 J with $$sim$$ 30 fs pulse duration for studying extremely high intensity laser matter interaction process and a small-scaled Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of $$sim$$ 100 m J of $$sim$$ 500 fs pulse duration for compact, high efficiency, high repetition system. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.

Oral presentation

Waste management scenario in hot cell for DEMO

Someya, Yoji; Tobita, Kenji; Kondo, Masatoshi*; Ueno, Kenichi; Yanagihara, Satoshi*; Matsuda, Shinzaburo*; Hatano, Yuji*; Masuzaki, Suguru*; Kato, Takashi*; Uto, Hiroyasu; et al.

no journal, , 

In the replacement period of a fusion power reactor, blanket and divertor modules should be removed from the reactor as an assembly for plant availability. It is assumed that the sector assembly is changed over at every two years during the operation. In the hot cell, the modules will be removed from the back plate of the assembly. Since the back plate made of F82H can be reused, the decay heat must be removed using active cooling to keep the temperature below 550 $$^{circ}$$C for structural strength of F82H. At the same time, the active cooling must not cause a contamination of the hot cell environment due to dispersion of tritium and tungsten dust. The cooling scenario is one of key points in the waste management. The problem is the space for storage. Breaking up the F82H into small pieces reduces the volume of the waste, contributing to a reduction of the storage space.

Oral presentation

Management strategy of radioactive waste in the fusion DEMO reactor

Someya, Yoji; Tobita, Kenji; Kondo, Masatoshi*; Yanagihara, Satoshi*; Uto, Hiroyasu; Sakamoto, Yoshiteru; Asakura, Nobuyuki; Hoshino, Kazuo; Nakamura, Makoto; Tokunaga, Shinsuke

no journal, , 

We are considering the reduction of radioactive waste which is generated in every replacement of an in-vessel component such as a blanket segment and divertor cassette for fusion DEMO reactor. Main parameters of DEMO reactor are 8.2 m of major radius and 1.35 GW of fusion output. Maintenance scheme is to replace the blanket segment and divertor cassette independently, as the lifetime of them is different. The blanket segment consists of some blanket modules mounted to back-plate. A conducting shell for plasma positional stability and high beta access is installed in between the blanket modules and back-plate. Total weight is estimated to amount to about 6,648 ton (1,575 ton of blanket module, 3,777 ton of back-plate, 372 ton of conducting shell and 924 ton of divertor cassette). The lifetimes of blanket segment and divertor cassette are assumed to be 4 years and 1 year, respectively, 9,420 ton wastes is generated in 4 years. Therefore, there is a concern that a contamination controlled area for the radioactive waste may increase because much the waste is generated in every replacement. In a hot cell, the blanket module is removed from the back-plate by a remote handing. A tritium, radioactive dust and decay heat are inherent in the in-vessel component. The hot cell environment for the maintenance is cooled by natural air convection to prevent diffusion of the tritium and radioactive dust. Since the hot cell made a concrete, on the other hand, the temperature of the hot cell must be maintained below 65$$^{circ}$$C for preventing water evaporation. As a result of thermal analysis, the maintenance of blanket segment is started after 6 years of storage until the temperature required for the concrete in the hot cell. 6 years after shutdown, a dominant contact dose rate of the component was 100 Sv/hour.

Oral presentation

Measurement of the free surface geometry on a curved open channel using color coding method

Ito, Takahiro*; Yamashita, Masatoshi*; Nishikawa, Masato*; Tsuji, Yoshiyuki*; Wakai, Eiichi; Kondo, Hiroo; Kanemura, Takuji; Nakaniwa, Koichi

no journal, , 

no abstracts in English

Oral presentation

Study on quantity fabrication and purity control of lithium-lead as fusion liquid breeder

Park, C.-H.; Kondo, Masatoshi*; Nozawa, Takashi; Tanigawa, Hiroyasu

no journal, , 

no abstracts in English

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