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Journal Articles

Hydrogen generation by water radiolysis with immersion of oxidation products of zircaloy-4

Matsumoto, Yoshinobu*; Do, Thi-Mai-Dung*; Inoue, Masao; Nagaishi, Ryuji; Ogawa, Toru

Journal of Nuclear Science and Technology, 52(10), p.1303 - 1307, 2015/10

 Times Cited Count:3 Percentile:32.14(Nuclear Science & Technology)

Effects of zirconium oxides and oxidation products of zircaloy-4 on water radiolysis were investigated to predict the hydrogen generation from the water-immersed debris after a severe accident of a nuclear power plant. Observed yields of hydrogen in water containing the oxides were measured as a function of their weight fractions. Assuming that energies of Co-60 $$gamma$$-ray deposited to water and the oxides brought about the water radiolysis to generate hydrogen independently, the radiolysis showed an additional term of hydrogen generation due to the energy deposition to the oxides. This term seemed to be dependent on the specific surface area or particle size of oxides, but not on the crystal structure of oxides in our experimental results. The oxides in distilled water gave the strong enhancement of term. The enhancement tended to saturate with increasing the weight fraction of oxides and was not apparent in the seawater.

Journal Articles

Consideration of radiolytic behavior in diluted and concentrated systems of seawater for computational simulation of hydrogen generation

Nagaishi, Ryuji; Inoue, Masao; Hino, Ryutaro; Ogawa, Toru

Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10

Since seawater has been used as a coolant for reactors and spent fuel pools in broken reactor buildings at Fukushima Daiichi NPS accident, radioactive contaminated water emitted following the accident has contained salt content of seawater at high concentrations, different from that at TMI-2 accident. Radiolysis of seawater leading to hydrogen generation and corrosion has been simulated and reported by several groups. However, the proposed radiolysis models cannot be always applied to water radiolysis at the wide range of salt concentrations present in the NPS, mainly because primary yields of radiolysis products of water and radiation-induced reactions are dependent on the salt concentration. In this study, the radiolytic behavior in diluted and concentrated systems of seawater was considered on the basis of results in steady state and pulse radiolysis experiments, in which the above salt effects were demonstrated from the obtained results.

Journal Articles

Development of divertor IR thermography for ITER

Takeuchi, Masaki; Sugie, Tatsuo; Ogawa, Hiroaki; Ishikawa, Masao; Shimada, Takahiko; Kusama, Yoshinori

Plasma and Fusion Research (Internet), 8(Sp.1), p.2402147_1 - 2402147_5, 2013/11

Divertor IR Thermography is one of the diagnostics which Japan is in charge of development in ITER project. The conceptual design has been performed so far, and the progress is reported here. By reducing the size of mirrors, and making the optical path a labyrinthine structure, the design of a new optics that fills requirements of both spatial resolution and neutron shielding has been advanced. To achieve the required measurement accuracy, the detected signal and the noises such as bremsstrahlung light, detector noise and thermal noise of optical components were evaluated. Higher photons than the bremsstrahlung light are obtained, excluding the low temperature range. The simulation calculation of reflection from wall was started. Detailed method of data processing of deriving the profiles of surface temperature in the divertor plates from the observed signals and in-situ calibration strategies of the optical system are important issues and will be discussed.

Journal Articles

In-beam $$gamma$$-ray spectroscopy of $$^{248,250,252}$$Cf by neutron-transfer reactions using a Cf target

Takahashi, 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:12 Percentile:64.15(Physics, Nuclear)

The ground-state bands of $$^{248,250,252}$$Cf have been established up to 10$$^{+}$$, 12$$^{+}$$, and 10$$^{+}$$ states, respectively, by in-beam $$gamma$$-ray spectroscopy using neutron-transfer reactions with a $$^{18}$$O beam and a highly radioactive Cf target. The deexcitation $$gamma$$ rays in $$^{248,250,252}$$Cf were identified by taking coincidences with outgoing particles of $$^{16-19}$$O measured with Si $$Delta E$$-$$E$$ detectors, and by selecting their kinetic energies. This is the first in-beam $$gamma$$-ray spectroscopy for Cf isotopes.

Journal Articles

Observation of high-$$j$$ quasiparticle states in $$^{249}$$Cm by in-beam $$gamma$$-ray spectroscopy using heavy-ion transfer reactions

Ishii, Tetsuro; Makii, Hiroyuki*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shigematsu, Soichiro*; Kaneko, Junichi*; Shizuma, Toshiyuki; et al.

Physical Review C, 78(5), p.054309_1 - 054309_11, 2008/11

 Times Cited Count:14 Percentile:67.09(Physics, Nuclear)

Journal Articles

In-beam $$gamma$$-ray spectroscopy of neutron-rich nuclei in the uranium region through the heavy-ion transfer reaction

Ishii, Tetsuro; Makii, Hiroyuki; Asai, Masato; Koura, Hiroyuki; Shigematsu, Soichiro*; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shizuma, Toshiyuki; et al.

Nuclear Physics A, 805(1-4), p.257 - 259, 2008/06

no abstracts in English

Journal Articles

Z dependence of the $$N = 152$$ deformed shell gap; In-beam $$gamma$$-ray spectroscopy of neutron-rich $$^{245, 246}$$Pu

Makii, Hiroyuki; Ishii, Tetsuro; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Kaneko, Junichi*; Tome, Hayato*; Ichikawa, Shinichi; et al.

Physical Review C, 76(6), p.061301_1 - 061301_5, 2007/12

 Times Cited Count:26 Percentile:83.64(Physics, Nuclear)

We have measured deexcitation $$gamma$$ rays for the first time in the neutron-rich nuclei of $$^{246}$$Pu$$_{152}$$ and $$^{245}$$Pu$$_{151}$$ produced by the ($$^{18}$$O, $$^{16}$$O) and the ($$^{18}$$O, $$^{17}$$O) reactions, respectively. The ground-state band of $$^{246}$$Pu was established up to 12$$^{+}$$ states. The systematics of the moments of inertia of $$_{94}$$Pu isotopes suggests that the $$N = 152$$ deformed subshell closure disappears in these isotopes. The measurements of deexcitation $$gamma$$ rays in $$^{245}$$Pu shows a small energy spacing between neutron orbitals at $$N = 152$$, which explans the disappearance of the subshell closure.

Journal Articles

In-beam $$gamma$$-ray study of the neutron-rich nuclei of $$^{240}$$U, $$^{246}$$Pu, and $$^{250}$$Cm produced by the ($$^{18}$$O, $$^{16}$$O) reaction

Ishii, Tetsuro; Shigematsu, Soichiro*; Makii, Hiroyuki; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shizuma, Toshiyuki; Kaneko, Junichi*; et al.

Physics of Atomic Nuclei, 70(8), p.1457 - 1461, 2007/08

 Times Cited Count:9 Percentile:58.39(Physics, Nuclear)

We have measured deexcitation $$gamma$$ rays in the neutron-rich nuclei of $$^{240}$$U, $$^{246}$$Pu and $$^{250}$$Cm. These nuclei were produced by the ($$^{18}$$O, $$^{16}$$O) two-neutron transfer reactions with a 200, 162 and 162 MeV $$^{18}$$O beams and a $$^{238}$$U, $$^{244}$$Pu and $$^{248}$$Cm targets, respectively, using the tandem accelerator at Tokai, Japan. The $$gamma$$ rays in residual nuclei were measured by taking coincidence with scattering particles using Si $$Delta E$$-$$E$$ detectors. We have identified $$gamma$$ rays in $$^{240}$$U, $$^{246}$$Pu and $$^{250}$$Cm by selecting the kinetic energies of $$^{16}$$O particles which correspond to the excitation energies in these nuclei below their neutron separation energies. The ground-state bands of $$^{240}$$U, $$^{246}$$Pu and $$^{250}$$Cm were established up to 12$$^{+}$$ states and the $$K^{pi}=0^{-}$$ octupole band of $$^{240}$$U was established up to 9$$^{-}$$ state. Because the deformations of these nuclei are well developed, the moments of inertia reflect the pairing gap, which is expected to be smaller, resulting in a larger moment of inertia, at the deformed shell closure. We have found that the moment of inertia of the ground-state band of $$^{248}$$Cm$$_{152}$$ is considerably larger than that of $$^{250}$$Cm$$_{154}$$. This fact supports the existence of the deformed subshell closure at $$N=152$$ in Cm isotopes. On the other hand, the moment of inertia of $$^{246}$$Pu$$_{152}$$ was found to be smaller than that of $$^{244}$$Pu$$_{150}$$, which suggests that the deformed subshell closure at $$N=152$$ weakens or disappears in Pu isotopes. These results are consistent with the prediction by a cranking model calculation.

Journal Articles

Magnetic fusion energy studies in Japan

Ogawa, Masao*; Iio, Shunji*; Komori, Akio*; Kawahata, Kazuo*; Kaneko, Osamu*; Inoue, Takashi; Kamada, Yutaka

Nuclear Instruments and Methods in Physics Research A, 577(1-2), p.30 - 36, 2007/07

 Times Cited Count:4 Percentile:36.92(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Ground-state bands of neutron-rich $$^{236}$$Th and $$^{242}$$U nuclei and implication of spherical shell closure at $$N=164$$

Ishii, Tetsuro; Makii, Hiroyuki; Asai, Masato; Koura, Hiroyuki; Shigematsu, Soichiro*; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Kaneko, Junichi*; et al.

Physical Review C, 76(1), p.011303_1 - 011303_5, 2007/07

 Times Cited Count:13 Percentile:67.67(Physics, Nuclear)

The ground-state bands of the neutron-rich $$^{236}$$Th and $$^{242}$$U nuclei were established up to spin 10 and 8, respectively, by in-beam $$gamma$$-ray spectroscopy using the ($$^{18}$$O, $$^{20}$$Ne) two-proton pickup reaction with a $$^{238}$$U and a $$^{244}$$Pu target. Deexcitation $$gamma$$ rays in $$^{236}$$Th and $$^{242}$$U were identified by selecting the kinetic energies of $$^{20}$$Ne using Si $$Delta E$$-$$E$$ detectors. The excitation energies of the first 2$$^{+}$$ states in U and Pu isotopes have local minima at $$N simeq 146$$, suggesting the possibility that nuclei with $$Z simeq 92$$ have a spherical shell closure of $$N=164$$. Calculation using the Koura-Yamada single-particle potential gives an energy gap of 1.8 MeV at $$N=164$$ for $$^{256}$$U.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 18

Kawahata, Kazuo*; Kawano, Yasunori; Kusama, Yoshinori; Mase, Atsushi*; Sasao, Mamiko*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(2), p.195 - 198, 2007/02

no abstracts in English

Journal Articles

Ground-state band of the neutron-rich transuranium nucleus $$^{250}$$Cm$$_{154}$$

Ishii, Tetsuro; Shigematsu, Soichiro; Makii, Hiroyuki; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shizuma, Toshiyuki; Kaneko, Junichi*; et al.

Journal of the Physical Society of Japan, 75(4), p.043201_1 - 043201_4, 2006/04

 Times Cited Count:19 Percentile:69.9(Physics, Multidisciplinary)

The ground-state band of the neutron-rich transuranium nucleus $$^{250}$$Cm was established up to spin 12 by in-beam $$gamma$$-ray spectroscopy using the two-neutron-transfer reaction with a $$^{248}$$Cm target and a 162 MeV $$^{18}$$O beam. Deexcitation $$gamma$$ rays in $$^{250}$$Cm were identified by selecting the kinetic energies of $$^{16}$$O particles with Si $$Delta E$$-$$E$$ detectors. The moment of inertia of $$^{250}$$Cm$$_{154}$$ is considerably smaller than that of $$^{248}$$Cm$$_{152}$$, which supports the existence of the deformed subshell closure at $$N=152$$ in Cm isotopes.

Journal Articles

In-beam $$gamma$$-ray spectroscopy of $$^{240}$$U using the ($$^{18}$$O,$$^{16}$$O) reaction

Ishii, Tetsuro; Shigematsu, Soichiro; Asai, Masato; Makishima, Akiyasu*; Matsuda, Makoto; Kaneko, Junichi*; Hossain, I.*; Ichikawa, Shinichi; Kono, Toshiyuki*; Ogawa, Masao*

Physical Review C, 72(2), p.021301_1 - 021301_5, 2005/08

 Times Cited Count:19 Percentile:76.78(Physics, Nuclear)

In the two-neutron-transfer reaction of a 200-MeV $$^{18}$$O beam with a $$^{238}$$U target, deexcitation $$gamma$$ rays in a neutron-rich nucleus of $$^{240}$$U were measured. The $$gamma$$ rays in $$^{240}$$U were identified by taking coincidence with $$^{16}$$O, using Si $$Delta E$$-$$E$$ detectors. The kinetic energies of $$^{16}$$O particles allowed us to select the excitation energies of $$^{240}$$U below the neutron separation energy. The ground-state band and the $$K^{pi}=0^{-}$$ octupole band of $$^{240}$$U were established up to 12$$^{+}$$ and 9$$^{-}$$, respectively. The octupole-band head of $$^{240}$$U is higher than those of $$^{236,238}$$U by about a hundred keV, suggesting that a secondary maximum of octupole correlations exists at $$N=144-146$$ in U isotopes.

Journal Articles

Impurity release and deuterium retention properties of a ferritic steel wall in JFT-2M

Ogawa, Hiroaki; Yamauchi, Yuji*; Tsuzuki, Kazuhiro; Kawashima, Hisato; Sato, Masayasu; Shinohara, Koji; Kamiya, Kensaku; Kasai, Satoshi; Kusama, Yoshinori; Yamaguchi, Kaoru*; et al.

Journal of Nuclear Materials, 329-333(Part1), p.678 - 682, 2004/08

 Times Cited Count:4 Percentile:30.82(Materials Science, Multidisciplinary)

no abstracts in English

JAEA Reports

Research and development of large current induction linac

Maebara, Sunao; Zheng, X.*; Watanabe, Akihiko*; Kishiro, Junichi*; Takayama, Ken*; Horioka, Kazuhiko*; Ogawa, Masao*; Kawasaki, Sunao*; Shiho, Makoto

JAERI-Research 2004-007, 40 Pages, 2004/03

JAERI-Research-2004-007.pdf:4.48MB

no abstracts in English

Journal Articles

Nanosecond isomers in neutron-rich N$$approx$$19 nuclei

Asai, Masato; Ishii, Tetsuro; Makishima, Akiyasu*; Ogawa, Masao*; Matsuda, Makoto

Fission and Properties of Neutron-Rich Nuclei; Proceedings of 3rd International Conference, p.295 - 297, 2003/10

Nanosecond isomers in neutron-rich N$$sim$$20 nuclei produced in the heavy-ion deep-inelastic collision have been searched for. Spin-parities of the isomers in $$^{32,33}$$Si and $$^{34}$$P have been identified through $$gamma$$-ray angular distribution and lifetime measurements. It has been found that these isomers arise from the neutron excitation on the $$f_{7/2}$$ orbitals.

Journal Articles

Impurity desorption behavior from low activation ferritic steel installed in the JFT-2M tokamak

Tsuzuki, Kazuhiro; Sato, Masayasu; Kawashima, Hisato; Ogawa, Hiroaki; Kimura, Haruyuki; Okano, Fuminori; Suzuki, Sadaaki; Komata, Masao; Sawahata, Masayuki; Shinohara, Koji; et al.

Journal of Nuclear Materials, 313-316, p.177 - 181, 2003/03

 Times Cited Count:9 Percentile:55.15(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Gamma-ray spectroscopy of the neutron-rich Ni region through heavy-ion deep-inelastic collisions

Ishii, Tetsuro; Asai, Masato; Makishima, Akiyasu*; Hossain, I.*; Kleinheinz, P.*; Ogawa, Masao*; Matsuda, Makoto; Ichikawa, Shinichi

European Physical Journal A, 13(1-2), p.15 - 19, 2002/01

no abstracts in English

Journal Articles

Nano-second isomers in neutron-rich Ni region produced by deep-inelastic collisions

Ishii, Tetsuro; Asai, Masato; Matsuda, Makoto; Ichikawa, Shinichi; Makishima, Akiyasu*; Hossain, I.*; Kleinheinz, P.*; Ogawa, Masao*

Acta Physica Polonica B, 32(3), p.739 - 746, 2001/03

no abstracts in English

Journal Articles

Nanosecond isomers in neutro-rich $$^{67}$$Cu and $$^{64}$$Co and a fast ${it E3}$ transition in $$^{67}$$Cu

Asai, Masato; Ishii, Tetsuro; Makishima, Akiyasu*; Hossain, I.*; Ogawa, Masao*; Ichikawa, Shinichi

Physical Review C, 62(5), p.054313_1 - 054313_7, 2000/11

 Times Cited Count:18 Percentile:68.98(Physics, Nuclear)

no abstracts in English

81 (Records 1-20 displayed on this page)