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Journal Articles

Dynamics of radiocaesium within forests in Fukushima; Results and analysis of a model inter-comparison

Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.

Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11

 Times Cited Count:8 Percentile:58.13(Environmental Sciences)

This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.

Journal Articles

Radionuclides from the Fukushima Daiichi Nuclear Power Plant in terrestrial systems

Onda, Yuichi*; Taniguchi, Keisuke*; Yoshimura, Kazuya; Kato, Hiroaki*; Takahashi, Junko*; Wakiyama, Yoshifumi*; Coppin, F.*; Smith, H.*

Nature Reviews Earth & Environment (Internet), 1(12), p.644 - 660, 2020/12

 Times Cited Count:66 Percentile:89.93(Environmental Sciences)

Journal Articles

Author correction; Radionuclides from the Fukushima Daiichi Nuclear Power Plant in terrestrial systems

Onda, Yuichi*; Taniguchi, Keisuke*; Yoshimura, Kazuya; Kato, Hiroaki*; Takahashi, Junko*; Wakiyama, Yoshifumi*; Coppin, F.*; Smith, H.*

Nature Reviews Earth & Environment (Internet), 1(12), P. 694_1, 2020/12

 Times Cited Count:0 Percentile:0.26(Environmental Sciences)

Journal Articles

Field-induced phenomena in ferromagnetic superconductors UCoGe and URhGe

Aoki, Dai*; Taupin, M.*; Paulsen, C.*; Hardy, F.*; Taufour, V.*; Kotegawa, Hisashi*; Hassinger, E.*; Malone, L.*; Matsuda, Tatsuma; Miyake, Atsushi*; et al.

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB002_1 - SB002_6, 2012/12

 Times Cited Count:3 Percentile:26.75(Physics, Multidisciplinary)

Journal Articles

Densified low-hygroscopic form of P$$_{2}$$O$$_{5}$$ glass

Brazhkin, V. V.*; Akola, J.*; Katayama, Yoshinori; Kohara, Shinji*; Kondrin, M. V.*; Lyapin, A. G.*; Lyapin, S. G.*; Tricot, G.*; Yagafarov, O.

Journal of Materials Chemistry, 21(28), p.10442 - 10447, 2011/07

 Times Cited Count:16 Percentile:46.21(Chemistry, Physical)

P$$_{2}$$O$$_{5}$$ compound is an archetypical glass-forming oxide with a high hygroscopicity. We found that the quenching from the P$$_{2}$$O$$_{5}$$melt under ultrahigh pressures enables obtaining densified P$$_{2}$$O$$_{5}$$ glasses with a residual densification up to 12% at normal conditions. These glasses have a low hygroscopicity and can exist under air conditions for several weeks. An examination of the structure of the new form of P$$_{2}$$O$$_{5}$$ glass reveals a cardinal decrease of the volume of nanovoids in the glassy matrix.

Journal Articles

Compressibility and polymorphism of $$alpha$$-As$$_{4}$$S$$_{4}$$ realgar under high pressure

Tuktabiev, M. A.*; Popova, S. V.*; Brazhkin, V. V.*; Lyapin, A. G.*; Katayama, Yoshinori

Journal of Physics; Condensed Matter, 21(38), p.385401_1 - 385401_7, 2009/08

 Times Cited Count:15 Percentile:57.98(Physics, Condensed Matter)

The energy-dispersive X-ray diffraction technique has been employed to study the structure and equation of state of realgar As$$_{4}$$S$$_{4}$$ under pressures up to 8 GPa at room temperature. We have obtained pressure dependences of the unit cell parameters and volume for the monoclinic structure of realgar. At a pressure of around 7 GPa, realgar showed a polymorph transition to a new molecular phase with a supposedly orthorhombic structure. The phase transition is likely to be associated with the removal of a monoclinic distortion in the unit cell.

Journal Articles

Nature of the structural transformations in B$$_{2}$$O$$_{3}$$ glass under high pressure

Brazhkin, V. V.*; Katayama, Yoshinori; Trachenko, K.*; Tsiok, O. B.*; Lyapin, A. G.*; Artacho, E.*; Dove, M.*; Ferlat, G.*; Inamura, Yasuhiro; Saito, Hiroyuki

Physical Review Letters, 101(3), p.035702_1 - 035702_4, 2008/07

 Times Cited Count:70 Percentile:90.25(Physics, Multidisciplinary)

We study polyamorphism of B$$_{2}$$O$$_{3}$$ glass using X-ray diffraction up to 10 GPa in the 300-700 K temperature range, in situ volumetric measurements up to 9 GPa, and first-principles simulations. The glass undergoes two-stage transformations under pressure including a gradual increase of the first B-O (O-B) coordination numbers above 5 GPa. The fraction of boron atoms in the fourfold-coordinated state at P$$<$$10 GPa is smaller than was assumed from inelastic X-ray scattering spectroscopy data, but is considerably larger than was previously suggested by the classical molecular dynamics simulations. The observed transformations under both compression and decompression are broad in hydrostatic conditions.

Journal Articles

Molecular-network-ionic structure transitions in liquid AlCl$$_{3}$$ and ZnCl$$_{2}$$ halogenides under pressure

Brazhkin, V. V.*; Lyapin, A. G.*; Popova, S. V.*; Katayama, Yoshinori; Saito, Hiroyuki; Utsumi, Wataru

Journal of Physics; Condensed Matter, 19(24), p.246104_1 - 246104_10, 2007/06

 Times Cited Count:23 Percentile:67.36(Physics, Condensed Matter)

Liquid AlCl$$_{3}$$ and ZnCl$$_{2}$$ halogenides are studied by ${it in-situ}$ high-pressure high-temperature X-ray diffraction measurements. These halogenides have a quasi-molecular network structure in liquid state at normal pressure. They are intermediate between pure covalent and ionic melts. The present study is indicative of a rapid and strong breakdown of an intermediate range order in a tetrahedral network of melts for the initial pressure range and points to rather sharp transitions in liquids with the formation of a short-range order structure similar to ionic melt structures. Such a two-stage structural transformation under pressure is the general feature for a wide class of simple melts, including most of the pseudo-covalent halogenides.

Journal Articles

Lattice parameters and thermal expansion of superconducting boron-doped diamonds

Brazhkin, V. V.*; Ekimov, E. A.*; Lyapin, A. G.*; Popova, S. V.*; Rakhmanina, A. V.*; Stishov, S. M.*; Lebedev, V. M.*; Katayama, Yoshinori; Kato, Kenichi*

Physical Review B, 74(14), p.140502_1 - 140502_4, 2006/10

 Times Cited Count:48 Percentile:84.61(Materials Science, Multidisciplinary)

Using two different high-pressure techniques, we have prepared boron-doped diamonds with atomic concentration of the dopant ranging from 0.04% to 4% (from 7$$times$$10$$^{19}$$ to 7$$times$$10$$^{21}$$ atom/cm$$^{3}$$) and studied the lattice constants and thermal expansion of the diamonds in the temperature range from 90 to 300 K. Both sets of samples demonstrate the same increasing concentration dependence of the lattice parameter with maximum shift of the lattice constant about 0.011${AA}$. We have established an abnormally high thermal expansion of the heavily boron-doped superconducting diamonds with respect to the undoped ones and a nearly linear correlation between lattice constant and critical temperature of the superconducting transition.

Journal Articles

Structural studies of phase transitions in crystalline and liquid Halides (ZnCl$$_{2}$$, AlCl$$_{3}$$) under pressure

Brazhkin, V. V.*; Katayama, Yoshinori; Lyapin, A. G.*; Popova, S. V.*; Inamura, Yasuhiro*; Saito, Hiroyuki; Utsumi, Wataru

JETP Letters, 82(11), p.713 - 718, 2005/12

 Times Cited Count:11 Percentile:55.67(Physics, Multidisciplinary)

The results of investigating the phase diagrams of ZnCl$$_{2}$$ and AlCl$$_{3}$$ halides, as well as the structure of the short range order of the corresponding melts under pressures up to 6.5 GPa, by the method of energy-dispersive X-ray diffraction are reported. When a ZnCl$$_{2}$$ crystal is compressed, a phase transition occurs from the $$gamma$$ phase (HgI$$_{2}$$ structure type) to the $$delta$$ phase (distorted CdI$$_{2}$$ structure, WTe$$_{2}$$ type). The structural studies of the liquid state of ZnCl$$_{2}$$ and AlCl$$_{3}$$ indicate that the intermediate-range order decreases rapidly in the tetrahedral network of both melts as the pressure increases to 1.8 and 2.3 GPa for ZnCl$$_{2}$$ and AlCl$$_{3}$$, respectively. With further compression, the transitions in both melts occur with a change in the structure of the short-range order and with an increase in the coordination number. In this case, the transition in AlCl$$_{3}$$ occurs at about 4 GPa and is a sharp first order transition, whereas the transition in ZnCl$$_{2}$$ occurs more smoothly in a pressure range of 2-4 GPa with a maximum intensity near 3 GPa. Thus the AlCl$$_{3}$$ and ZnCl$$_{2}$$ compounds exemplify the existence of two phenomena, gradual decay of intermidiate-range structural correlations and a sharper liquid-liquid coordination transition.

Journal Articles

External feedback effect on magnetic islands in tokamaks

Konovalov, S. V.; Mikhailovskii, A. B.*; Kovalishen, E. A.*; Kamenets, F. F.*; Ozeki, Takahisa; Shirokov, M. S.*; Takizuka, Tomonori; Tsypin, V. S.*

Doklady Physics, 49(7), p.405 - 408, 2004/07

 Times Cited Count:1 Percentile:11.8(Mechanics)

Effect of feedback system, placed outside the vacuum vessel, on neoclassical tearing modes (NTMs) in tokamaks is analytically studied. External matching parameters for magnetic island chain are derived for the simplest case of step profile of equilibrium parallel current. The structure of dynamical equations for the island width and island rotation frequency in terms of matching parameters is explained. It is shown that such a feedback system can lead to essential shift of the island rotation, in particular, for stabilization of NTMs by the polarization current effect.

Journal Articles

Microislands in tokamaks

Mikhailovskii, A. B.*; Kovalishen, E. A.*; Shirokov, M. S.*; Konovalov, S. V.; Tsypin, V. S.*; Kamenets, F. F.*; Ozeki, Takahisa; Takizuka, Tomonori

Physics of Plasmas, 11(2), p.666 - 676, 2004/02

 Times Cited Count:6 Percentile:20.05(Physics, Fluids & Plasmas)

Analytical treatment of magnetic islands with high poloidal mode numbers and widths smaller than ion Larmor radius (microislands) is presented. The profile functions and rotation frequencies of microislands are investigated with the two-fluid magnetohydrodynamics. The microislands are described in terms of two profile functions, one of which characterizes the electric field and perturbed plasma density, and second the perturbed electron temperature. The problem of rotation frequencies of microislands is discussed.

Journal Articles

Effects of parallel viscosity on rotation of magnetic islands in tokamaks

Konovalov, S. V.; Mikhailovskii, A. B.*; Tsypin, V. S.*; Kovalishen, E. A.*; Shirokov, M. S.*; Ozeki, Takahisa; Takizuka, Tomonori

Physics Letters A, 318(4-5), p.429 - 434, 2003/11

 Times Cited Count:7 Percentile:46.58(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Transport threshold model of subsonic neoclassical tearing modes in tokamaks

Mikhailovskii, A. B.*; Shirokov, M. S.*; Tsypin, V. S.*; Konovalov, S. V.; Ozeki, Takahisa; Takizuka, Tomonori; Galv$~a$o, R. M. 0.*; Nascimento, I. C.*

Physics of Plasmas, 10(10), p.3975 - 3983, 2003/10

 Times Cited Count:8 Percentile:25.91(Physics, Fluids & Plasmas)

A transport threshold model of subsonic neoclassical tearing modes (NTMs) in tokamaks is developed. The basic procedure is to include the velocity-dependent term into the single-fluid heat-conductivity equation. and to supply the parallel plasma motion equation. These equations permit the determination of the perturbed plasma temperature and the bootstrap current drive of NTMs, for both strong and weak perpendicular heat transport. It is shown that the subsonic NTMs transport threshold model can be more realistic than the standard transport threshold model of NTMs.

Journal Articles

Fluid treatment of convective-transport threshold model of neoclassical tearing modes in tokamaks

Mikhailovskii, A. B.*; Shirokov, M. S.*; Tsypin, V. S.*; Konovalov, S. V.*; Ozeki, Takahisa; Takizuka, Tomonori; Galv$~a$o, R. M. 0.*; Nascimento, I. C.*

Physics of Plasmas, 10(9), p.3790 - 3792, 2003/09

 Times Cited Count:5 Percentile:16.93(Physics, Fluids & Plasmas)

A fluid treatment of convective-transport threshold model of neoclassical tearing modes (NTMs) in tokamaks is developed. A system of moment equations of the drift kinetic equation with a model perpendicular transport is derived. The essence of this moment equation system is to allow for the parallel heat flux on an equal footing with pressure and temperature. The suggested moment equation system is applied for analyzing the bootstrap current drive of NTMs. As a result, a threshold model of these modes is derived, which coincides qualitatively with the convective-transport threshold model initially formulated by means of intuitive consideration.

Journal Articles

Drift stabilization of internal resistive-wall modes in tokamaks

Konovalov, S. V.; Mikhailovskii, A. B.*; Tsypin, V. S.*; Galv$~a$o, R. M. 0.*; Nascimento, I. C.*

Plasma Physics Reports, 29(9), p.779 - 784, 2003/09

 Times Cited Count:2 Percentile:6.18(Physics, Fluids & Plasmas)

The problem of drift stabilization of internal resistive-wall modes (RWMs) in tokamaks is theoretically investigated. The basic assumption of our model is that these modes are unstable in the absence of a conducting wall and stable in the presence of a close-fitting ideally conducting wall, when drift effects are neglected. Stability of the internal RWMs, was estimated for several existing tokamaks contributing to the ITER data base, namely, AUG (ASDEX-Upgrade), DIII-D, JET, TFTR and JT-60U, as well as for the projected ITER-FEAT. It is concluded that although drift effects do not stabilize the internal RWMs in current devices, they should be effective for suppressing these modes in reactor-grade tokamaks.

Journal Articles

Aqueous solutions of uranium(VI) as studied by time-resolved emission spectroscopy; A Round-robin test

Billard, I.*; Ansoborlo, E.*; Apperson, K.*; Arpigny, S.*; Azenha, M.-E.*; Birch, D.*; Bros, P.*; Burrows, H. D.*; Choppin, G. R.*; Couston, L.*; et al.

Applied Spectroscopy, 57(8), p.1027 - 1038, 2003/08

 Times Cited Count:50 Percentile:88.25(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Structural transformations in liquid, crystalline, and glassy B$$_{2}$$O$$_{3}$$ under high pressure

Brazhkin, V. V.*; Katayama, Yoshinori; Inamura, Yasuhiro; Kondrin, M. V.*; Lyapin, A. G.*; Popova, S. V.*; Voloshin, R. N.*

JETP Letters, 78(6), p.393 - 397, 2003/06

 Times Cited Count:29 Percentile:77.53(Physics, Multidisciplinary)

We present in situ (X-ray diffraction) and ex situ (quenching) structural studies of crystalline, liquid, and glassy B$$_{2}$$O$$_{3}$$ up to 9 GPa and 1700 K, drawing equilibrium and nonequilibrium phase diagrams of B$$_{2}$$O$$_{3}$$, Particularly, we have determined the melting curve, the stability regions for crystalline B$$_{2}$$O$$_{3}$$ and B$$_{2}$$O$$_{3}$$ II modifications, the regions of transformations, such as densification or crystallization, for both the liquid and glassy states, including the region of sharp first-order-like transition in liquid B$$_{2}$$O$$_{3}$$ to a high-density phase near 7 GPa. Quenching experiments also show that the transition to the high-density liquid can occur at much lower pressures in nonstoichiometric melts with an excess of boron. B$$_{2}$$O$$_{3}$$ is the first glassformer whose transformations in the disordered state have been comparatively studied for both liquid and glassy phases.

Journal Articles

Possible nature of nonideal perturbations limiting plasma pressure in Tokamaks

Mikhailovskii, A. B.*; Churikov, A. P.*; Konovalov, S. V.; Shirokov, M. S.*; Tsypin, V. S.*

Doklady Physics, 48(4), p.159 - 162, 2003/04

 Times Cited Count:1 Percentile:12.87(Mechanics)

It is shown that there is a new class of perturbations, limiting the pressure of ideally stable plasma in the conditions of fusion reactors of tokamak type. localization of such modes includes three characteristic regions: large-scale (MHD), Larmor and sub-Larmor ones. It is suggested that these modes can be responsible for spontaneous generation of neoclassical tearing modes observed experimentally.

Journal Articles

Phenomenon identification and ranking tables (PIRTs) for rod ejection accidents in pressurized water reactors containing high burnup fuel

Boyack, B. E.*; Motta, A. T.*; Peddicord, K. L.*; Alexander, C. A.*; Deveney, R. C.*; Dunn, B. M.*; Fuketa, Toyoshi; Higar, K. E.*; Hochreiter, L. E.*; Langenbuch, S.*; et al.

NUREG/CR-6742, 263 Pages, 2001/09

no abstracts in English

24 (Records 1-20 displayed on this page)