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Ogawa, Yasuo*; Ichiki, Masahiro*; Kanda, Wataru*; Mishina, Masaaki*; Asamori, Koichi
Earth, Planets and Space (Internet), 66(1), p.158_1 - 158_13, 2014/12
Times Cited Count：77 Percentile：91.83(Geosciences, Multidisciplinary)We have analyzed three-dimensional resistivity structure around Naruko volcano, NE Japan. From the inversion of full tensor components, the following model features are found. Sub-vertical conductors exist at Naruko volcanoes below a depth of few kilometers. The conductor reaches to the surface of Naruko volcano and deepens southward away from the volcano along the backbone ranges. High seismicity in the upper crust is observed above and around the conductors. This implies that the seismicity is fluid-driven and also that the fluid trap is created by the precipitation of quartz due to loss of solubility at shallow depth.
Izawa, Kazuhiko; Aoyama, Yasuo; Sono, Hiroki; Ogawa, Kazuhiko; Yanagisawa, Hiroshi; Miyoshi, Yoshinori
Proceedings of 9th International Conference on Nuclear Criticality (ICNC 2011) (CD-ROM), 11 Pages, 2012/02
For reactor physics and criticality safety researches, the Static Experiment Critical Facility (STACY) will be modified. In the modification, the present STACY, solution-fuel-type homogeneous cores, will be converted to fuel-pin-type heterogeneous cores moderated by light water. For nuclear safety design of the modified STACY, computational analyses have been carried out by using a Monte Carlo code MVP and a transport code system DANTSYS with cross-section data based on the JENDL-3.3. In the analyses, basic nuclear characteristics have been evaluated, such as criticality, water-level worth and reactor shutdown margin. By the results of these analyses, the feasibility of reactivity control mechanism and the sufficiency of reactor shutdown margin of the modified STACY were confirmed. In addition, temperature and void coefficients of reactivity and kinetic parameters were obtained to comprehend nuclear characteristics of the modified STACY.
collisions at 
= 200 and 62.4 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.
Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06
Times Cited Count：184 Percentile：99.44(Physics, Nuclear)Transverse momentum distributions and yields for 
, and 
in collisions at = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different collisions. We also present the scaling properties such as 
and 
scaling and discuss the mechanism of the particle production in collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.
and Au+Au collisions at 
= 200 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.
Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04
Times Cited Count：8 Percentile：49.7(Physics, Nuclear)Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.
Asamori, Koichi; Umeda, Koji; Ogawa, Yasuo*; Oikawa, Teruki*
International Journal of Geophysics, 2010, 7 Pages, 2010/10
The two-dimensional electrical resistivity structure beneath Naruko Volcano was determined using magnetotelluric soundings. The resulting model shows that a prominent conductor exists in the crust beneath the volcano. The location of the conductor agrees closely with a seismic low-velocity zone. Hypocenters of low-frequency micro-earthquakes are located adjacent to the conductor. The cut-off depth of shallow micro-earthquakes becomes shallow toward the west side of the volcanic center and it is coincident with the upper boundary of the conductor. Furthermore, new helium isotope data from hot springs around the volcano were obtained. The high 
He/
He ratios are obtained near the volcano. The maximum He/He ratio is located in proximity to this peak and decrease toward away from the volcanic center. This supports the likelihood of mantle-derived materials supplying beneath the volcano. These results indicate that the conductor beneath the volcano is due to high-temperature fluids consisting of magma and related aqueous fluids.
-ray spectroscopy of 
Cf by neutron-transfer reactions using a Cf targetTakahashi, Ryuta; Ishii, Tetsuro; Asai, Masato; Nagae, Daisuke*; Makii, Hiroyuki; Tsukada, Kazuaki; Toyoshima, Atsushi; Ishii, Yasuo; Matsuda, Makoto; Makishima, Akiyasu*; et al.
Physical Review C, 81(5), p.057303_1 - 057303_4, 2010/05
Times Cited Count：13 Percentile：63.2(Physics, Nuclear)The ground-state bands of Cf have been established up to 10
, 12, and 10 states, respectively, by in-beam -ray spectroscopy using neutron-transfer reactions with a 
O beam and a highly radioactive Cf target. The deexcitation rays in Cf were identified by taking coincidences with outgoing particles of 
O measured with Si 
-
detectors, and by selecting their kinetic energies. This is the first in-beam -ray spectroscopy for Cf isotopes.
Shirasu, Noriko; Kuramoto, Kenichi; Nakano, Yoshihiro; Yamashita, Toshiyuki; Kimura, Yasuhiko; Nihei, Yasuo; Ogawa, Toru
Journal of Nuclear Materials, 376(1), p.88 - 97, 2008/05
Times Cited Count：13 Percentile：64.63(Materials Science, Multidisciplinary)The concept of the rock-like oxide (ROX) fuel has been developed for the annihilation of excess plutonium in light water reactors. Irradiation tests and post-irradiation examinations were carried out on candidate ROX fuels. The ternary fuel of YSZ-spinel-corundum system, the single-phase fuels of YSZ, the particle dispersed fuels of YSZ in spinel or corundum matrix, and the blended fuels of YSZ and spinel or corundum matrix were fabricated and submitted to irradiation tests. The fuels containing spinel showed chemical instabilities with the vaporization of MgO component, which caused fuel restructuring. The swelling behavior was improved with the particle-dispersed fuels. However, the particle-dispersed fuels showed higher fractional gas release (FGR) than blended type fuels. The FGR of YSZ single-phase fuels were comparable to what would be expected for UO
fuels. The YSZ single-phase fuel showed the best irradiation performance among the ROX fuels investigated.
Izawa, Kazuhiko; Aoyama, Yasuo; Sono, Hiroki; Ogawa, Kazuhiko; Yanagisawa, Hiroshi
JAEA-Technology 2007-001, 40 Pages, 2007/02
JAEA-Technology-2007-001.pdf:2.73MB
A series of critical experiments is conducted in FY 2006 using a heterogeneous core of the Static Experiment Critical Facility (STACY) in the Japan Atomic Energy Agency (JAEA). In the experiment, the core is composed of uranyl nitrate solution (
U enrichment 6wt%) containing soluble poison (gadolinium) and 333 pins of uranium dioxide (U enrichment 5wt%) loaded at a latticepitch of 1.5cm. Prior to the experiment, the following neutronic characteristics were analyzed to assess safety of the core and operation parametor limits: criticality, reactivity and reactor shutdown margins. In the analyses, a Monte Carlo code, MVP, and a neutronics code system, SRAC, were used with an evaluated nuclear data library, JENDL-3.3. From these analyses, it was confirmed that the reactor shutdown margins would comply with the safety criteria under all conditions of the fuel used in the experiments. Simplified formulas for criticality and reactivity were also evaluated based on the analyzed values which are utilized to confirm the operation parameter limits during operations of the core.
Umeda, Koji; Asamori, Koichi; Negi, Tateyuki*; Ogawa, Yasuo*
Geochemistry, Geophysics, Geosystems (Internet), 7(8), p.Q08005_1 - Q08005_8, 2006/08
Times Cited Count：37 Percentile：62.25(Geochemistry & Geophysics)Mesozoic crystalline mountains (Iide Mountains) in a non-volcanic region of the Northeast Japan arc were imaged by wide-band magnetotelluric soundings. A two-dimensional model shows that an anomalous conductive body is clearly visible beneath the Iide Mountains. The conductor widens with increasing depth, and extends from the near-surface down to the base of the crust and perhaps into the upper mantle. Considering several independent indications of the possibility of crustal magma storage, such as a high-temperature regime, hot spring gases with high He/He ratios, thinning of the brittle seismogenic layer and anomalous low seismic velocity, it is reasonable to suppose that the conductor reflects partial melt and/or high-temperature aqueous fluids in the crust, related to renewed magmatism in the present-day subduction system.
Izawa, Kazuhiko; Seki, Masakazu; Hirose, Hideyuki; Kaminaga, Jota; Aoyama, Yasuo; Yoshida, Hiroshi; Sono, Hiroki; Ogawa, Kazuhiko; Sakuraba, Koichi
UTNL-R-0453, p.9_1 - 9_10, 2006/03
no abstracts in English
He emanation and conductive anomaly in a non-volcanic region, Kii Peninsula, southwest JapanUmeda, Koji; Ogawa, Yasuo*; Asamori, koichi; Oikawa, Teruki
Journal of Volcanology and Geothermal Research, 149(1-2), p.47 - 61, 2006/01
Times Cited Count：44 Percentile：70.85(Geosciences, Multidisciplinary)Aqueous fluids derived from the subducting slab: observed high He emanation and cinductive anomaly in a non-volcanic region, Kii Peninsula, southwest Japan
Umeda, Koji; Uehara, Daijiro; Ogawa, Yasuo*; Kudo, Takeshi; Kakuta, Chifumi
Kazan, 48(6), p.461 - 470, 2003/12
None
Minato, Kazuo; Akabori, Mitsuo; Takano, Masahide; Arai, Yasuo; Nakajima, Kunihisa; Ito, Akinori; Ogawa, Toru
Journal of Nuclear Materials, 320(1-2), p.18 - 24, 2003/09
Times Cited Count：53 Percentile：94.59(Materials Science, Multidisciplinary)In the Japan Atomic Energy Research Institute, the concept of the transmutation of minor actinides (MA: Np, Am and Cm) with accelerator-driven systems is being studied. The MA nitride fuel has been chosen as a candidate because of the possible mutual solubility among the actinide mononitrides and excellent thermal properties besides supporting hard neutron spectrum. MA nitrides of AmN, (Am,Y)N, (Am,Zr)N and (Cm0.4Pu0.6)N were prepared from the oxides by the carbothermic reduction method. The prepared MA nitrides were examined by X-ray diffraction and the contents of impurities of oxygen and carbon were measured. The fabrication conditions for MA nitrides were improved so as to reduce the impurity contents. For an irradiation test of U-free nitride fuels, pellets of (Pu,Zr)N and PuN+TiN were prepared and a He-bonded fuel pin was fabricated. The irradiation test started in May 2002 and will go on for two years in the Japan Materials Testing Reactor.
Arai, Yasuo; Ogawa, Toru
Kaku Nenryo, p.33_9 - 33_10, 2000/06
no abstracts in English
Arai, Yasuo; Ogawa, Toru
Proceedings of 6th OECD/NEA International Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation, p.445 - 457, 2000/00
no abstracts in English
Suzuki, Yasufumi; Ogawa, Toru; Arai, Yasuo; Mukaiyama, Takehiko
Actinide and Fission Product Partitioning and Transmutation, p.213 - 221, 1998/00
no abstracts in English
; Ogawa, Toru; Osugi, Toshitaka; Arai, Yasuo; Mukaiyama, Takehiko
Proc. of 4th Int. Information Exchange Meeting on Actinide and Fission Product Partitioning and Transm, 0, p.178 - 188, 1997/00
no abstracts in English
Ogawa, Toru; Omichi, Toshihiko; Maeda, Atsushi; Arai, Yasuo;
Journal of Alloys and Compounds, 224, p.55 - 59, 1995/00
Times Cited Count：23 Percentile：78.26(Chemistry, Physical)no abstracts in English
Umeda, Koji; Asamori, Koichi; Negi, Tateyuki*; Ogawa, Yasuo*
no journal, ,
Mesozoic crystalline mountains (Iide Mountains) in a non-volcanic region of the Northeast Japan arc were imaged by wide-band magnetotelluric soundings. A two-dimensional model showed that an anomalous conductive body (
10 ohm-m) is clearly visible beneath the Iide Mountains. The conductor widens with increasing depth, and extends from the near-surface down to the base of the crust and perhaps into the upper mantle. Considering several signals imaging the presence of crustal magma storage, such as high-temperature regime, hot spring gases with high He/He ratio, thinning of the brittle seismogenic layer and anomalies of low seismic velocity, it is reasonable to suppose that the conductor reflects partial melt and/or high-temperature aqueous fluids in the crust, related to renewed magmatism in the present-day subduction system.
Asamori, Koichi; Umeda, Koji; Negi, Tateyuki*; Ogawa, Yasuo*
no journal, ,
no abstracts in English
