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JAEA Reports

Studies on the design method of multi tunnels in geological disposal facility, 4

Hayashi, Katsuhiko; Kishi, Hirokazu; Kabayashi, Yasushi*; Takebe, Atsuji*; Fujiyama, Tetsuo*; Hiramoto, Masayuki*; Mizutani, Kazuhiko*; Morita, Atsushi*

JAEA-Research 2010-059, 92 Pages, 2011/03

JAEA-Research-2010-059.pdf:3.71MB

In this study, the first investigation is the order of the multi-tunnels excavation. The second is the strain-softening model for multi-tunnels which is based on test data at Horonobe site. As results of first investigation, we showed as 2 dimensional analyses that it was desirable to excavate the tunnel of the remote distance at first and excavate the tunnel between these tunnels next, and it is necessary for the examination that reflected a real plan, such as evacuation machine and actual multi tunnel layout. As the results of second investigation, we also showed the more reliable EDZ by using the strain-softening model that is based on test data at Horonobe site. Furthermore, we standardized the design method (draft) for the practical use by referring the past studies of multi tunnel design method.

JAEA Reports

A Study on the technology for reducing cement-type materials used for tunnel supports at high-level radioactive waste disposal sites (Joint research)

Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Kabayashi, Yasushi*; Nakama, Shigeo; Fujita, Tomo; Naito, Morimasa; Tada, Hiroyuki*; Kumasaka, Hiroo*; Goke, Mitsuo*; et al.

JAEA-Research 2010-057, 101 Pages, 2011/03

JAEA-Research-2010-057.pdf:7.47MB

Cement-type materials that are used for supports or grouting at high-level radioactive waste disposal facilities leach into the groundwater and create a highly alkaline environment. Of concern in highly alkaline environments are the alteration of bentonite used as buffers or backfill materials, and of surrounding rock mass, and the increased uncertainty regarding the provision of performance of the disposal system over a long period of time. In this study, to reduce the quantity of cement-type materials that cause highly alkaline environments, technical feasibility of the support structure including the materials which considered the long-term performance of the HLW disposal system are discussed by using knowledge and technology accumulated in JAEA and Shimizu Construction. Moreover, based on the results, the problems remained in the application to the future HLW disposal institution are summarized.

JAEA Reports

Studies about strength recovery and generalized relaxation behavior of rock, 3

Hayashi, Katsuhiko; Kishi, Hirokazu; Kabayashi, Yasushi*; Takebe, Atsuji*; Okubo, Seisuke*

JAEA-Research 2009-058, 106 Pages, 2010/02

JAEA-Research-2009-058.pdf:18.82MB

In this study, experimental studies on the strength recovery, the generalized stress relaxation behavior and the tensile strength were conducted using samples obtained from the Wakkanai-formation shale. As the results, the strength recovery has time-dependent characteristics. It was founded that the generalized stress relaxation behavior depends on the draining conditions. Furthermore, regarding the tensile strength, complete stress-strain curve under uniaxial tensile strength conditions was gotten and it was found that there is small residual strength. The results of uniaxial tensile strength in this year are almost same as the minimum value of splitting tensile strength test results.

JAEA Reports

Studies on the design method of multi tunnels in geological disposal facility, 3

Hayashi, Katsuhiko; Kishi, Hirokazu; Kabayashi, Yasushi*; Takebe, Atsuji*; Fujiyama, Tetsuo*; Hiramoto, Masayuki*; Mizutani, Kazuhiko*; Morita, Atsushi*

JAEA-Research 2009-056, 86 Pages, 2010/02

JAEA-Research-2009-056.pdf:9.96MB

In this study, the effect of constitutive models such as strain softening of rock masses for EDZ, and the stress relief ratio used for multi tunnels analysis were conducted. As the result, it is necessary to confirm mechanical behavior of in situ rock and it is important to choose suitable constitutive models, and it is possible for all tunnels in multi tunnels model to have same stress relief ratio.

JAEA Reports

Measurement of $$^{241}$$Am, $$^{243}$$Am Fission Cross Sections at YAYOI

Okawachi, Yasushi; Oki, Shigeo; Wakabayashi, Toshio; Yamaguchi, Kenji*; Yamawaki, Michio*

JNC TY9400 2004-004, 37 Pages, 2004/05

JNC-TY9400-2004-004.pdf:1.03MB

In the framework of the study on transmutation of minor actinide (MA) nuclides with fast reactors, the fission cross section ratios of MA (241Am, 243Am) relative to 235U have been measured by using a back-to-back (BTB) fission chamber at YAYOI fast neutron source reactor. The compact BTB fission chamber was prepared for the measurements in the main experimental hole (Glory hole) passing though the core of YAYOI. Dependence of fission cross section ratios on neutron spectrum was investigated by changing the measurement position in Glory hole from core center to depleted uranium blanket.The measured values of fission cross section ratios were compared with those calculated with the following nuclear data libraries: JENDL-3.2, ENDF/B-VI, and JEF-2.2. It was found that the calculated values for both 241Am and 243Am in the center of the core systematically underestimated the measurements by 10 to 20%. Dispersion of the calculated values among the nuclear data libraries was smaller than the above difference from the measured value. We also see the dependence of C/E value on the measurement position.The present result remained some issues in terms of the measurement accuracy. If we can get rid of those causes, for example, by means of the unfolding technique on pulse height distribution, the result could be utilized as expletive information in nuclear data validation not only for 241Am and 243Am but also for 235U and 238U which characterize the neutron spectrum.

Journal Articles

An Insight into the pathway of the amyloid fibril formation of hen egg white lysozyme obtained from a small-angle X-ray and neutron scattering study

Yonezawa, Yasushige*; Tanaka, Shimpei*; Kubota, Tomomi*; Wakabayashi, Katsuzo*; Yutani, Katsuhide*; Fujiwara, Satoru

Journal of Molecular Biology, 323(2), p.237 - 251, 2002/10

 Times Cited Count:71 Percentile:74.49(Biochemistry & Molecular Biology)

It is known that hen egg white lysozyme (HEWL) forms amyloid fibrils in highly concentrated ethanol solutions. In order to gain an insight into the mechanism of the amyloid fibril formation, the structures of HEWL in solutions of various protein and ethanol concentrations were investigated with small-angle X-ray and neutron scattering. It was shown that the structural states of HEWL were distinguished as the monomer state, the state of the dimer formation, the state of the protofilament formation, the protofilament state, and the state towards the formation of the amyloid fibrils. Circular dichroism measurements showed that the large changes in the secondary structures of HEWL occurred during the dimer formation. Structural characterization showed that the dimers had an elongated shape, the protofilaments were formed by stacking of the dimers with their long axis (nearly) perpendicular to the protofilament axis, and the changes of the structural states towards the amyloid fibril formation occurred via lateral association of the protofilaments.

Journal Articles

Measurements of neutron induced fission cross-section for $$^{242m}$$Am from 0.003eV to 10keV using lead slowing-down spectrometer, thermal neutron facility and time-of-flight method

Kai, Tetsuya; Kobayashi, Katsuhei*; Yamamoto, Shuji*; Cho, H.*; Fujita, Yoshiaki*; Kimura, Itsuro*; Okawachi, Yasushi*; Wakabayashi, Toshio*

Annals of Nuclear Energy, 28(8), p.723 - 739, 2001/05

 Times Cited Count:7 Percentile:50.11(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Design study on H.L.W. geologic repository, IV; for 1984

Ara, Hiroshige*; Fukumitsu, Kenji*; Iizuka, Yunosuke*; Ishii, Takashi*; Izumiya, Yasushi*; Imazu, Masanori*; Utsugida, Yoshizo*; Hasegawa, Makoto*; Maeda, Masaya*; Yabe, Yukio*; et al.

PNC TJ199 84-04VOL1, 20 Pages, 1984/03

PNC-TJ199-84-04VOL1.pdf:0.88MB

None

Oral presentation

Application of probability risk assessment in TRP and its capability to maintenance planning

Takase, Yuki; Miura, Yasushi; Nakabayashi, Hiroki

no journal, , 

Tokai Reprocessing plant (TRP), which temporarily suspended the reprocessing of spent fuel in 2007, moved to decommissioning in 2018 without restarting operations. Under the decommissioning situation, the high-level radioactive liquid waste generated in the past reprocessing operation is the highest potential risk in TRP. These high-level radioactive liquid wastes are stored in High Active Liquid Waste Storage Facility (HAW) and sequentially Vitrified in Tokai Vitrification Facility (TVF). The serious accident risk about evaporation accident of high radioactive liquid waste has been remained in both facilities. In this study, a loss of heat sink (LOHS) frequency of high radioactive liquid waste in HAW and TVF was assessed by Probability Risk Assessment (PRA). The risk information was extracted for the equipment of important of safety related system from the view point of maintaining the facility safety. Its capability to maintenance planning was evaluated.

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