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Journal Articles

The Effect of oxidation-and-quenching process during a LOCA on the behavior of the oxidation and embrittlement of Zircaloy-4 cladding under reheating transients

Miwa, Hideki; Amaya, Masaki

Journal of Nuclear Science and Technology, 53(12), p.2090 - 2097, 2016/12

 Times Cited Count:5 Percentile:49.65(Nuclear Science & Technology)

Two-sided oxidation tests, ring compression tests and semi-integral quench tests on Zircaloy-4 cladding specimens were conducted under the temperature transient conditions simulating a post-quench reheat transient in order to evaluate the effect of high temperature oxidation and quenching during a LOCA on the behavior of the oxidation and embrittlement of the cladding under a loss of long-term-core-cooling condition. Test specimens prepared from non-irradiated Zircaloy-4 cladding tube were oxidized at a temperature between 1173 and 1473 K in steam flow and quenched by soaking the specimen in room temperature water. By using the test specimens, re-heating tests were performed in steam flow at a temperature between 1173 and 1473 K. The suppression of oxide layer growth and weight gain was observed under certain reheating-after-quenching conditions. Nevertheless, it seemed that the temperature transients including quenching-and-reheating process did not significantly affect the embrittlement of cladding. It was found that the embrittlement behavior of cladding during the temperature transients including quenching-and-reheating process could be dealt with on the basis of the ECR based on Baker-Just correlation.

Journal Articles

Fission-track ages of late Pliocene to Pleistocene strata around the eastern margin of the Yokote Basin active fault zone, northeast Japan

Kosaka, Hideki*; Kagohara, Kyoko; Miwa, Atsushi*; Imaizumi, Toshifumi*; Kurosawa, Hideki; Nohara, Tsuyoshi

Chigaku Zasshi, 117(5), p.851 - 862, 2008/10

To understand the development process of the fault zone, fission-track ages of rocks and rock facies are investigated in western margin of the Ou Backbone Range of Northeast Japan. Fission-track dating was carried out for 5 acid volcanic rocks from the late Pliocene to Pleistocene strata which were deposit associated with mountain belt growth. Statistically significant ages obtained are 1.5$$pm$$0.1 Ma (OB-03) and 1.85$$pm$$0.1 Ma (YG-01) for the Tazawa Formation, 1.6$$pm$$0.3 Ma (FT-01) for the Kurisawa Formation,0.93$$pm$$0.14 Ma (FT-02) and 2.7$$pm$$0.3 Ma (FT-03) for the Senya Formation. According to the fission-track dating in this study, ages of the mountain belt growth with acid volcanic activity are estimated to before 1 Ma.

Journal Articles

Crush zone structure in a compressional step; An Example of the western part of the Atotsugawa Fault, Hida City, Gifu Prefecture of Japan

Niwa, Masakazu; Shimada, Koji; Kurosawa, Hideki; Miwa, Atsushi*

Chishitsugaku Zasshi, 114(10), p.495 - 515, 2008/10

This paper provides a geological description of crush zones in the western part of the active Atotsugawa Fault, Gifu Prefecture of Japan, to understand crush zone structures in steps of strike-slip faults. By means of aerial photograph interpretation, we recognized that the occurrence of a step is suggestive in the Sangawara area, and that a long strand of the Atotsugawa Fault with ENE-WSW trend is traced in the Itani Area. On the Basis of the detailed geological observation, attitude and sense of shear planes, and thickness and clay mineral composition of fault gouge are different between crush zones of the Sangawara and Itani areas. In the Sangawara area, shear planes with NNE-SSW and NW-SE strikes, high-angle oblique to the trend of the Atotsugawa Fault, are characteristically developed. These shear planes can be a part of the composite planar fabric such as R2 surfaces which are dominantly developed within compressional steps.

Journal Articles

Grain boundary character of cracks observed in IASCC and IGSCC

Miwa, Yukio; Kaji, Yoshiyuki; Tsukada, Takashi; Kato, Yoshiaki; Tomita, Takeshi; Nagata, Nobuaki*; Dozaki, Koji*; Takiguchi, Hideki*

Proceedings of 13th International Conference on Environmental Degradation of Materials in Nuclear Power Systems (CD-ROM), 14 Pages, 2007/00

Grain boundary (GB) character of cracks observed in irradiation assisted stress corrosion cracking (IASCC) and in intergranular stress corrosion cracking (IGSCC) was examined using the orientation imaging microscope (OIM). IASCC were produced by constant load tests with 1/4T-CT specimens for pre-irradiated (1.8 dpa at 546 K) type 304 stainless steel. The tests for pre-irradiated specimens were performed by the post irradiation SCC test or the in-reactor SCC test at the Japan Materials Testing Reactor. In all specimens, cracks propagated mainly along random grain boundaries (GBs), and small amount of cracks propagated along low angle GBs ($$Sigma$$ 1), twin GBs ($$Sigma$$ 3) and coincidence site lattice (CSL) GBs ($$Sigma$$ 5-27). Fraction of the GB character was compared with the author's previous studies in which the fraction of IGSCC in thermally-sensitized type 304 stainless steel and unirradiated type 316L stainless steel were measured on CT specimens and a BWR shroud sample. The relationship between SCC behavior and the GB character was discussed. It was considered that the difference of the fraction of GB character between IASCC and IGSCC related to the deformation mode of irradiated stainless steel such as dislocation channelling.

Journal Articles

Active tectonics of the Senya Hills and evolution of the Senya Active Fault, Eastern margin of the Yokote Basin Fault Zone, Northeast Japan

Kagohara, Kyoko*; Imaizumi, Toshifumi*; Miyauchi, Takahiro*; Sato, Hiroshi*; Uchida, Takuma*; Echigo, Tomoo*; Ishiyama, Tatsuya*; Matsuta, Nobuhisa*; Okada, Shinsuke*; Ikeda, Yasutaka*; et al.

Chigaku Zasshi, 115(6), p.691 - 714, 2006/12

The eastern marginal fault zone of the Yokote Basin is one of seismogenic reverse faults developed in Northeast Japan, generating the 1896 Riku-u Earthquake (M7.2). We discussed the relationship among fault traces, geomorphic displacements and fault geometries on the Senya fault, based on a data from high-resolution seismic reflection profiling, investigations in tectonic geomorphology and structural geology, with the help of the balanced cross section method. By the restoring the balanced cross sections, the horizontal shortening amount is estimated to be totally 3 km through the thrust system, and the thrusting is retroactive to 2.4 Ma. Depending on the strike of fault traces and the morphotectonic features, the Senya fault is subdivided into three, the northern, central and southern portion. The initiation of thrust front migration is ca.1.6 Ma at the central portion and 0.6 Ma at the northern portion. This means that the central portion preceded the northern portion as an emergent fault, and suggests that the initial propagated fault extends from the fault end to the boundary fault.

Journal Articles

Preliminary report on a new fault exposure of the Senya fault associated with the Rikuu earthquake in 1896, Northeast Japan

Imaizumi, Toshifumi*; Kagohara, Kyoko*; Otsuki, Kenshiro*; Miwa, Atsushi*; Kosaka, Hideki*; Nohara, Tsuyoshi

Katsudanso Kenkyu, (26), p.71 - 77, 2006/06

no abstracts in English

Journal Articles

Behavior of free surface vortices in cylindrical vessel under fluctuating flow rate

Monji, Hideaki*; Akimoto, Toshinori*; Miwa, Daisuke*; Kamide, Hideki

Proceedings of 11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-11) (CD-ROM), 10 Pages, 2005/09

In this study, the unsteady flow structure of the free surface vortex was investigated under periodical flow fluctuating conditions in a cylindrical vessel. The gas core length of the free surface vortex and the velocity field in the vessel were measured by image processing. The experimental results showed that the gas core length under the fluctuating flow condition was shorter than that in the steady state having the same flow rate as the maximum rate of the fluctuating flow when the period of the flow fluctuation was short.

JAEA Reports

Investigation about long-term change of the water vein geological structure of the focus dislocation circumference

Miwa, Atsushi*; Kurosawa, Hideki*

JNC TJ7420 2005-122, 176 Pages, 2004/03

JNC-TJ7420-2005-122.pdf:54.84MB

In this study, we have investigated around the earthquake source fault of the Western Tottori Prefecture Earthquake 2000 in order to presume a long-term change of the groundwater structure.

JAEA Reports

Geological structure investigation for 3-dimensional geological structure modeling of a reversed fault belt

Miwa, Atsushi*; Kurosawa, Hideki*

JNC TJ7420 2005-108, 101 Pages, 2004/03

In the 3-dimensional geological structure model, the data of the interpretation of sectional view of the seismic reflecting method, a geologic map, active fault information, and the inversion tectonics of northeast Japan were made reference, and it created on the scale of 1/50,000. As a result of verifying the accuracy of the model as compared with a gravity inquiry result, the error of base rock form is less than 1km. However, base rock form is the accuracy of the synthetic model after the back-arc basin formative period after 15Ma In order for the influence range of an active fault belt to verify from now on, data, such as airborne geophysics and gravity of the accuracy which the modification after the east-and-west strong compression term (2.4Ma or subsequent ones) after inversion tectonics.

Journal Articles

Beam-palarization asymmetries for the $$p$$($$overrightarrow{gamma}$$,$$K$$$$^{+}$$)$$Lambda$$ and $$p$$($$overrightarrow{gamma}$$,$$K$$$$^{+}$$)$$Sigma$$$$^{0}$$ reactions for $$E$$$$_{gamma}$$=1.5-2.4 GeV

Zegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat$'e$, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.

Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08

 Times Cited Count:128 Percentile:94.91(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Evidence for a narrow $$S$$ = +1 Baryon resonance in photoproduction from the neutron

Nakano, Takashi*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Date, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; Fujiwara, Mamoru; et al.

Physical Review Letters, 91(1), p.012002_1 - 012002_4, 2003/07

 Times Cited Count:1003 Percentile:99.86(Physics, Multidisciplinary)

no abstracts in English

JAEA Reports

Groundwater behavior around of The Western Tottori prefecture Earthquake Source Fault in 2000

Miwa, Atsushi*; Kurosawa, Hideki*

JNC TJ7420 2005-121, 81 Pages, 2003/03

Drastic water level changes in wells near the epicenter were often observed with comparatively large inland earthquakes. Some mechanisms of the co-seismic groundwater level changes were reported. Rojstaczer, (1992) suggested that the earthquake increased rock permeability and temporarily enhanced ground-water flow rates. Sibson (1992) suggested that increase of the crustal strain causes the increase in pore water pressure. In this study, we have investigated the groundwater behaviors in and around the earthquake Source Fault of the Western Tottori prefecture earthquake 2000 by interview and analysis of observed values of the ground water level and of river level.

JAEA Reports

The Research of chemical composition in the rock near the fault

Miwa, Atsushi*; Kurosawa, Hideki*; Ichikawa, Yasuo*

JNC TJ7420 2005-097, 60 Pages, 2002/03

JNC-TJ7420-2005-097.pdf:18.2MB

Macro- and microscopic structures of the fault rocks included in the core from the 389.52m borehole across the Nojima Fault are described to show the groundwater flow model around the underground fracture zone.

JAEA Reports

None

Miwa, Atsushi*; Kurosawa, Hideki*

JNC TJ7420 2005-120, 77 Pages, 2001/03

None

Oral presentation

Distribution and feature of fracture zone in fault steps; An Eexample of the western part of the Atotsugawa Fault

Niwa, Masakazu; Shimada, Koji; Nohara, Tsuyoshi; Miwa, Atsushi*; Kurosawa, Hideki*

no journal, , 

Detailed topographical and geological researches for understanding fracture zone structures in fault steps are necessary to estimate the extent of the mechanical damage to basement rocks due to strike-slip fault activities. Our research of the western part of the Atotsugawa Fault in the Hida City, Gifu Prefecture shows that the faults high-angle oblique to the principal direction of the Atotsugawa Fault characteristically occur in fault steps, which effect that the fracture zone increases in width. The Atotsugawa fault, which is one of the Class A active faults, trends ENE-WSW and shows dextral strike-slip displacement. We firstly checked the occurrence of the fault step in the Miyagawa-cho area of the western part of the Atotsugawa Fault by way of aerial photograph interpretation. Then we researched the distribution and feature of fracture zone in the Kawai-cho area where the fault continues lineally and in the Miyagawa-cho area where the fault steps. In the Kawai-cho area, Fault planes mostly strike ENE-WSW to E-W and dip steeply N or S, subparallel to the principal direction of the Atotsugawa Fault. Width of the fracture zone is several tens meters. In the Miyagawa-cho area, NW-SE and N-S strike faults dominantly occur as well as ENE-WSW to E-W strike faults. Width of the fracture zone is more than a hundred meter. Remarkable existence of NW-SE and N-S strike faults distinguishes the fracture zone in the Miyagawa-cho area as that in the Kawai-cho area.

Oral presentation

In-pile IASCC study in Japan Materials Testing Reactor, 4; Water chemistry measurement by ECP under high neutron flux

Miwa, Yukio; Hanawa, Satoshi; Matsui, Yoshinori; Tsukada, Takashi; Nagata, Nobuaki*; Dozaki, Koji*; Takiguchi, Hideki*

no journal, , 

no abstracts in English

Oral presentation

Electrochemical potential measurement of stainless steel in BWR water environment under high radiation field at JMTR

Miwa, Yukio; Tsukada, Takashi; Sato, Tomonori; Hanawa, Satoshi; Matsui, Yoshinori; Nagata, Nobuaki*; Dozaki, Koji*; Takiguchi, Hideki*

no journal, , 

no abstracts in English

Oral presentation

Solid target performance against decay heat

Kikuchi, Kenji; Takenaka, Nobuyuki*; Kawai, Masayoshi*; Miwa, Hideki*

no journal, , 

Ta claded W generates decay heat after proton bombardment in the spallation target station. Assuming a loss of coolant, water feeding experiment was done and integrity of solid target was investigated if a peeling-off of claded material was caused or not.

Oral presentation

Investigation of crack initiation behavior using pre-irradiated austenitic stainless steel at JMTR

Tsukada, Takashi; Ugachi, Hirokazu; Kaji, Yoshiyuki; Miwa, Yukio; Nakano, Junichi; Matsui, Yoshinori; Endo, Shinya; Kato, Yoshiaki; Nagata, Nobuaki*; Dozaki, Koji*; et al.

no journal, , 

Irradiation Assisted Stress Corrosion Cracking (IASCC) has been regarded in recent years as the matter that is related to the reliability for core components of LWRs. The in-pile IASCC initiation tests were performed using of uniaxial constant load specimens pre-irradiated to about 5$$times$$10$$^{24}$$n/m$$^{2}$$ and 1$$times$$10$$^{25}$$n/m$$^{2}$$ at JMTR under the simulated BWR core condition. From the results of in-pile and out-of-pile tests of the irradiated specimens, we confirmed that any remarkable acceleration effect of synergy of neutron/$$gamma$$ radiation and stress/water environment on SCC initiation results was not observed under the test condition of this study. On the surface of in-pile test specimen, a micro crack was observed on the surface of specimen, and it was considered to be an initiation of SCC besed on the results of out-of-pile experiments.

Oral presentation

Examination of an investigation technique for activity on a fault-related fold in the Tenpoku region, northern Hokkaido, Japan

Nohara, Tsuyoshi; Kosaka, Hideki*; Kagohara, Kyoko*; Miwa, Atsushi*; Tokiwa, Tetsuya; Imaizumi, Toshifumi*

no journal, , 

Activity in the fault-related fold zone in the Tenpoku region, where the influence of the interplate coupling is comparatively small, has been investigated to explain the contradiction between geomorphological and geodetic information. Moreover, the actual average shortening rate of the Sarobetsu fault zone was investigated using the balanced cross section analytical method that used 2D Move. The results of this study show that the estimation of the long term crustal shortening rate in a fault-related fold zone, based on information from the geological structure, is important. In this study, it has been confirmed that information on the deformation of the geological structure is consistent to information on the tectonic landform. A multiple lines of evidence approach, including geomorphological, geological and geodetic investigation methods, will reduce uncertainty related to the average shortening rate along the fault of the fault-related fold.

Oral presentation

Effect of reheating on the oxidation behavior of Zircaloy-4 cladding quenched during LOCA

Miwa, Hideki; Amaya, Masaki

no journal, , 

no abstracts in English

21 (Records 1-20 displayed on this page)