Effects of heterogeneity of geomechanical properties on tunnel support stress during tunnel excavation

Okazaki, Yasuyuki*; Hayashi, Hisashi*; Aoyagi, Kazuhei; Morimoto, Shingo*; Shinji, Masato*

Proceedings of 5th ISRM Young Scholars' Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future (YSRM 2019 and REIF 2019) (USB Flash Drive), 6 Pages, 2019/12

In the design of tunnel support, the behavior of the rock mass around a tunnel and the stress acting on the tunnel support may be predicted using a numerical analysis. However, in such a numerical analysis, it is common to assume that each stratum comprises a homogeneous material, ignoring the heterogeneity of the geomechanical properties inherent to the rock mass. For this reason, it is not unusual for the results of the numerical analysis to differ from the actual behavior. We performed a tunnel excavation analysis considering the heterogeneity of the geomechanical properties in the rock mass to investigate the local increase in the tunnel support stress obtained in the 350 m gallery at the Horonobe Underground Research Laboratory. The results revealed that, in order to predict the locally increased support stress in advance, it is necessary to carry out a tunneling excavation analysis considering the heterogeneity of the geomechanical properties. It was also revealed that the scale at which the geomechanical properties fluctuate is an important factor.

High-precision mass analysis of RI sample for cross-section measurements

Nakamura, Shoji; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu

KURRI Progress Report 2016, P. 66, 2017/07

http://www.rri.kyoto-u.ac.jp/PUB/report/PR/ProgRep2016/CO2.pdf

In the ImPACT project, high-precision mass analysis was performed on a Cs standard solution for using Cs included in the standard solution as an impurity to measure the Cs cross-sections. A Cs standard solution of only 10Bq (pg order) was analyzed, and the isotope ratio of Cs and Cs was obtained with an accuracy of 0.5%.

Effects of secondary depressurization on core cooling in PWR vessel bottom small break LOCA experiments with HPI failure and gas inflow

Suzuki, Mitsuhiro; Takeda, Takeshi; Asaka, Hideaki; Nakamura, Hideo

Journal of Nuclear Science and Technology, 43(1), p.55 - 64, 2006/01

https://doi.org/10.3327/jnst.43.55

Effects of non-condensable gas from the accumulator tanks on secondary depressurization, as one of accident management (AM) measures in case of high pressure injection system failure, are studied at the ROSA-V/LSTF experiments simulating a ten instrument-tube break LOCA at the PWR vessel bottom. In an experiment with no gas inflow, the secondary depressurization at -55 K/h initiated by SI signal with 10 minutes delay succeeded in the LPI actuation. On the other hand, the gas inflow in another experiment degraded the primary depressurization and resulted in core uncovery before the LPI start. The third experiment with rapid secondary depressurization and continuous auxiliary feedwater supply, however, showed a possibility of long-term core cooling by the LPI actuation. RELAP5/MOD3 code analyses well predicted these experiment results and clarified that condensation heat transfer was largely degraded by the gas in the U-tubes. In addition, a primary pressure - coolant mass map was found to be useful for indication of key plant parameters of AM measures.

Development of frequency stabilized laser system for long-lived isotope analysis, 1; Development of Littrow configuration extended cavity diode laser

Miyabe, Masabumi; Oda, Koichi*; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo

JAERI-Tech 2004-064, 33 Pages, 2004/10

JAERI-Tech-2004-064.pdf:1.89MB

In nuclear waste materials there are various radionuclides to which standard analytical techniques are difficult to be applied. We are developing an analytical technique where such nuclides are analyzed using multi-step resonance ionization mass spectrometry. In this study, we have developed an external cavity diode laser applicable to the analysis. The wavelength and output power dependence on injection current and temperature were investigated for various types of laser diodes. Based on the data, we have obtained a suitable condition to operate the ECDL in stable single-mode oscillation, so that a continuous scanning range of about 100 GHz was realized. Additionaly, to evaluate the bandwidth of the developed ECDL, we have performed Doppler-free spectroscopy. The reasonable agreement of the measured isotope shift and HFS splitting with the reported values demonstrated that the developed ECDL is applicable to a precise laser spectroscopy as well as a laser trace analysis.

In the case of Japan Atomic Energy Research Institute

Azumi, Masafumi

Purazuma, Kaku Yugo Gakkai-Shi, 80(5), p.378 - 381, 2004/05

https://doi.org/10.1585/jspf.80.378

Progress of large scale scientific simulation environment in JAERI is briefly described. The expansion of fusion simulation science have been played a key role in the increasing performances of super computers and computer network system in JAERI. Both scalar parallel and vector parallel computer systems are now working in Naka and Tokai sites respectively and, particle and fluid simulation codes developed under the fusion simulation project, NEXT, are running on each system. The storage grid system has been also successfully developed for the effective visualization analysis by remote users. Fusion research is going to enter the new phase of ITER, and the need for the super computer system with higher performance are increasing more than as ever along with the development of reliable simulation models.

Replication of individual snow crystals for their subsequent chemical analysis using micro-PIXE

Kasahara, Mikio*; Ma, C.-J.*; Okumura, Motonori*; Kojima, Takuji; Hakoda, Teruyuki; Sakai, Takuro; Arakawa, Kazuo

JAERI-Review 2003-033, TIARA Annual Report 2002, p.270 - 272, 2003/11

https://jopss.jaea.go.jp/pdfdata/JAERI-Review-2003-033-p0188-p0390.pdf

A snow crystal scavenges earozol particles and trasfer various elements in atomosphere through heterogenious nucleation. The snow has many complicated crystal shapes which results in difficulty in comparison of its environmental purification function directly with that of raindrops. The replica of individual snow crystal grain was prepared by their immobilization on the collodion film. The replica samples were analized by micro-PIXE at JAERI and PIXE st Kyoto university. The following results are obtained: (1) Size(circumscribed diameter) of individual snow crystal are in the range of 0.12-2.5mm, (2)snow crystal grows from hexagnal plate to dendritic sectored plate, (3) major elements captured by a snow crystal are Si,S,K,Ca,Fe,S, (4)there is relation between snow crystal size and captured-element masses. The result leads us to presume the chemical inner-structure and the elemental mixing state in/on single snow crystal.

RELAP5/MOD3 analysis of a ROSA-IV/LSTF loss-of-RHR experiment with a 5% cold leg break

C.J.Choi*; Nakamura, Hideo

Annals of Nuclear Energy, 24(4), p.275 - 285, 1997/00

https://doi.org/10.1016/S0306-4549(96)00072-2

no abstracts in English

On the chemical sputtering of oxygen-exposed molybdenum

; H.Gnaser*; W.O.Hofer*

Applied Physics A, 40, p.197 - 202, 1986/00

https://doi.org/10.1007/BF00616594

no abstracts in English

Study on Porosity of Nuclear Graphite by Activation Analysis and Mass-Spectrometry

; ; ;

JAERI-M 7223, 22 Pages, 1977/08

JAERI-M-7223.pdf:0.88MB

no abstracts in English

High precision noble gas isotope measurement by NGX multi-collector noble gas mass spectrometer

Tamura, Hajimu; Kokubu, Yoko; Umeda, Koji

no journal, , 

JAEA installed an IsotopX NGX noble gas mass spectrometer with an water sample oriented preparation system in Tono Geoscience Center to measure helium accumulation age and neon isotope ratio of ground water for estimation of ground water stability on long term geological stability survay on geological disposal of nuclear waste. High precision isotope analysis by multi-collector mass spectrometer is neccessary tool for neon isotope analysis of young ground water due to small isotopic variation of neon for nucleogenic reaction or mixing of volcanic fluids in ground water. NGX-004 was configured for simultanous measurement of neon isotopes with 2 faradays for Ne and Ne, and 1 SEM for Ne spaced out 1 m/z each other. 10.084 0.002 of Ne/Ne and 0.02598 0.00004 of Ne/Ne were obtained by ohm faraday and ohm faraday, and ion count and ohm faraday, which is able to resolve 0.2% difference.