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Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Murai, Naoki; Kira, Hiroshi*; Nakatani, Takeshi; et al.
Journal of Physics; Conference Series, 1021(1), p.012030_1 - 012030_6, 2018/06
Times Cited Count：3 Percentile：88.67(Nuclear Science & Technology)Okubo, Seisuke*; Fukui, Katsunori*; Hashiba, Kimihiro*; Hikima, Ryoichi; Tanno, Takeo; Sanada, Hiroyuki; Matsui, Hiroya; Sato, Toshinori
JAEA-Research 2011-040, 54 Pages, 2012/02
JAEA-Research-2011-040.pdf:2.85MB
With respect to high-level radioactive waste disposal, knowledge of the long-term mechanical stability of shafts and galleries excavated in rock are required, not only during construction and operation but also over a period of thousands of years after closure. Therefore, it is very important to understand the time-dependent behavior of rock for evaluating long-term mechanical stability. This report describes the results of the activities in FY2010. In Chapter 1, we provide an overview and the background to this study. In Chapter 2, the results of a long-term creep test on Tage tuff, started in FY1997 are described. In Chapter 3, the relation of loading-rate dependency of strength and stress dependency of creep life, the relationship of time dependency and probability distribution of strength or creep life and size effects are discussed to indicate more clearly the meaning of the value of "n" to express the degree of time dependency of the rock. In Chapter 4, failure criterions of a rock mass considering time dependency are discussed. In Chapter 5, the FEM analysis implemented with a generalized variable-compliance-type constitutive equation considering the change of "n" in confining pressure and strength distribution of rock mass carried out to clarify the long-term behavior of Toki granite is described. Finally, based on the numerical analysis, an in situ testing method is proposed.
Okubo, Seisuke*; Hikima, Ryoichi; Hirano, Toru*; Matsui, Hiroya
JAEA-Research 2010-031, 45 Pages, 2010/10
JAEA-Research-2010-031.pdf:1.22MB
Rock shows time-dependent behavior such as creep/relaxation. With respect to high-level radioactive waste disposal, knowledge of the long-term mechanical stability of shafts and galleries excavated in rock are required, not only during construction and operation but also over a period of thousands of years after closure. Therefore, it is very important to understand the time-dependent behavior of rock for evaluating long-term mechanical stability. The purpose of this study is determining the mechanisms of time-dependent behavior of rock by the precise test, observation and measurement, to develop methods for evaluating long-term mechanical stability. In previous work, testing techniques have been established and basic evaluation methods were developed. Recently, some parameters needed for simulation of time-dependent behavior were determined at the Mizunami underground research facilities. However, we did not have enough data to check on the reliability of the evaluation method for these parameters. This report describes the results of the activities in fiscal year 2009. In Chapter 1, we provide an overview and the background to this study. In Chapter 2, the results of the long-term creep test on Tage tuff, started in fiscal year, 1997 are described. In Chapter 3, methods for obtaining parameters of the constitutive equation for rock are reviewed and summarized. The time dependent behavior of Toki granite and Inada granite (40-80 
C) are also summarized based on data obtained prior to the previous fiscal year. In Chapter 4, the FEM analysis implemented with a generalized variable-compliance-type constitutive equation carried out to clarify the long-term behavior of Toki granite is described. Finally, based on the numerical analysis, an in situ testing method is proposed.
crystalAkahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi
Optics Letters, 33(5), p.494 - 496, 2008/03
Times Cited Count：2 Percentile：14.69(Optics)A diode-pumped, cryogenically-cooled Yb:LuLiF regenerative amplifier has been developed for the first time to our knowledge. A chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated 
6-mJ, 13-ps pulses at 999 nm wavelength without a pulse compressor. Simultaneous lasing at 999 nm and 1024 nm, respectively, was demonstrated, which could be used for different frequency generation in the THz region.
Akahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi
no journal, ,
A diode-pumped, cryogenically-cooled Yb
:LuLiF
regenerative amplifier has been developed for the first time to our knowledge, which generated 6-mJ, 13-ps pulses at 999 nm wavelength without a pulse compressor.
:LuLiF crystalAkahane, Yutaka; Aoyama, Makoto; Kubo, Ryoichi; Sugiyama, Akira; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi
no journal, ,
A diode-pumped, cryogenically-cooled Yb:LuLiF regenerative amplifier has been developed for the first time to our knowledge, which generated 6-mJ, 13-ps pulses at 999 nm wavelength without a pulse compressor.
Akahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi; Tsuji, Koichi; Ogawa, Kanade; Yamakawa, Koichi
no journal, ,
We have developed a diode-pumped, cryogenically-cooled Yb:LuLiF regenerative amplifier, for the first time to our knowledge, which amplified 999 and 1024 nm chirped seed pulse to 6 and 8.5 mJ, respectively. Durations of amplified laser pulses in the regen were compressed to 13.2 ps and 27.4 ps in 999 and 1024 nm amplification, respectively, by gain-narrowing of chirped pulses, which enables us to apply output laser pulses to nonlinear applications directly without additional pulse compressor. We have also demonstrated simultaneous two-color lasing at 999 nm and 1024 nm, which could be used for different frequency generation in the THz region.
:LuLiF crystalAkahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi*; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi
no journal, ,
A diode-pumped regenerative amplification with cryogenically cooled Yb : LuLiF crystal has been demonstrated for the first time to our knowledge. A chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated 6 mJ, 13 ps pulses at 999 nm in wavelength and 8.5 mJ, 27 ps pulses at 1024 nm, respectively, without a pulse compressor. Simultaneous lasing at 999 and 1024 nm was demonstrated, which could be used for different frequency generation in the terahertz region.
:LuLiF crystalAkahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi*; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi
no journal, ,
We have performed chirped-pulse regenerative amplification at 999 nm and 1024 nm wavelengths with cryogenically-cooled Yb:LuLiF crystal. High-energy amplified pulses with energies of 6 mJ and 8.5 mJ were obtained at 999 nm and 1024nm wavelengths, respectively. In the regen durations of output pulses were compressed to 13 ps and 27 ps, respectively by gain-narrrwoing, so these pulses are available as pump sources for nonlinear effects without additional pulse compression devices. Simultaneous two-color lasing was also performed in this study, which is available for differential frequency generation in THz region.
Nakamura, Mitsutaka; Kajimoto, Ryoichi; Inamura, Yasuhiro; Aoyama, Kazuhiro; Kambara, Wataru*; Kawakami, Kazuhiro; Kubo, Naoya; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; et al.
no journal, ,
We have developed a newly designed Fermi chopper for MLF/BL01 4SEASONS, and has been open for users since March 2015. It was found that the gain factor achieved in the low-energy region is more than 10, thus, we succeeded to greatly improve the measurement efficiency of 4SEASONS. In this presentation we will show the details of both specification and design for a newly-developed Fermi chopper.
Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Nakajima, Kenji; Kawamura, Seiko; Nakatani, Takeshi; Kambara, Wataru*; Kubo, Naoya; Aoyama, Kazuhiro; Kawakami, Kazuhiro; et al.
no journal, ,
no abstracts in English
Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Nakajima, Kenji; Kawamura, Seiko; Nakatani, Takeshi; et al.
no journal, ,
no abstracts in English
Nakamura, Mitsutaka; Kajimoto, Ryoichi; Inamura, Yasuhiro; Aoyama, Kazuhiro; Kambara, Wataru*; Kawakami, Kazuhiro; Kubo, Naoya; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; et al.
no journal, ,
The chopper spectrometer 4SEASONS at J-PARC MLF had used a Fermi chopper borrowed from the SNS facility until 2014. A new Fermi chopper which reviewed the design of the slit package has recently started operation. As a result, we have succeeded in achieving the intensity gain up of to several tens of times in the low-energy region. In this presentation we will report the details of spec and design of a new Fermi chopper.
Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Kawakita, Yukinobu; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Aoyama, Kazuhiro; Kambara, Wataru*; Yamauchi, Yasuhiro; Kubo, Naoya
no journal, ,
AMATERAS is a cold-neutron multi disk-chopper spectrometer at Materials and Life Science Experimental Facility (MLF) in J-PARC. The spectrometer has had the first neutron beam in May 2009 and had the first user in December 2009. The user program on AMATERAS is running successfully for 5 years. In this presentation, we will present the current status of AMATERAS together with ideas of future upgrade plans.
Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Murai, Naoki; Nakatani, Takeshi; Kubo, Naoya*; et al.
no journal, ,
no abstracts in English
Ookubo, Manabu; Shimizu, Ryo; Hatori, Masakazu; Kobayashi, Takanori; Uekura, Ryoichi
no journal, ,
Under the circumstances where the fuel is disposed in the reactor core and the furnace fuel storage tank during the decommissioning measures of "Monju" where the decay heat is at an extremely low level, while preventing the sodium from being frozen by the preheater heater, It is desirable to continue operation of cooling the dissipated heat released into the compartment by ventilating air conditioning equipment. However, the operation of ventilation air conditioning equipment is designed for normal operation of nuclear reactors, and it is necessary to review the proper operation according to the situation at the stage of decommissioning. In this report, we will summarize the relationship between the actual load and the capacity of the ventilating and air conditioning equipment based on the past operation data and report on the status of consideration on rational ventilation air conditioning equipment operation at the decommissioning stage.
