Positron annihilation study of hardening in Fe-Cu alloy during low temperature aging

Yamashita, Takako*; Katsuyama, Jinya; Sato, Kaoru*; Mizuno, Masataka*; Araki, Hideki*; Shirai, Yasuharu*

Tetsu To Hagane, 97(11), p.558 - 565, 2011/11

https://doi.org/10.2355/tetsutohagane.97.558

The hardness of Fe-Cu alloys is known to increase by the precipitation of Cu clusters during thermal aging. However, the mechanism of Cu precipitation has not been clarified yet. In this study, the positron lifetime and coincidence Doppler broadening techniques have been used to investigate the recovery behavior of lattice defects such as vacancies, vacancy clusters and dislocations as well as the diffusion behavior of Cu atoms of cold rolled and thermally-aged Fe-Cu alloys. Both vacancies and dislocations caused by cold rolling were reduced through the thermally aging process. Some dislocations remained even after aging at 550C, although the vacancies almost disappeared after aging at 300C. Cu clusters precipitate mainly on the dislocations, where is the sinks of the vacancies, caused by the diffusion of Cu atom and vacancies.

Effects of Kinetic Radionuclide Sorption onto Colloids for Radionuclide Transport in Fractured Rock; Experimental and Numerical Studies

Kurosawa, Susumi; Ibaraki, Motomu*; Yui, Mikazu; Ueta, Shinzo*; Yoshikawa, Hideki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(3), p.249 - 256, 2004/09

https://doi.org/10.3327/taesj2002.3.249

Colloidal effect is one of the major factors to enhance the transport of radionuclide in groundwater. In this study, the impact of kinetic reactions of radionuclide sorption onto both the fracture wall and colloid on the transport behavior of radionuclide were investigated by carrying out the transport experiment of the radionuclide with colloid through fractured rock. In the experiments, the Cs and clay colloid were used as moderately sorbing radionuclide and typical natural colloid by the concentration of 1.010 g/l (7.510 mol/l) and 3.510 g/l, respectively. The granodiorite with artificially the single fracture (dimension: 50500.5 mm) was used. The results of the transport experiments were analyzed by numerical simulation code of radionuclide transport COLFRAC which can model radionuclide transport based on either equilibrium or kinetic reaction of radionuclide sorption onto fracture wall and colloid. Consequently, it was indicated that calculated results strongly dep

Experimental and Numerical Studies on Colloid-Enhanced Radionuclide Transport; The Effect of Kinetic Radionuclide Sorption onto Colloidal Particles

Kurosawa, Susumi; Ibaraki, Motomu*; Yui, Mikazu; Ueta, Shinzo*; Yoshikawa, Hideki

Materials Research Society Symposium Proceedings, Vol.824, 473 Pages, 2004/00

We conducted a series of laboratory experiments to investigate the effects of radionuclide sorption onto colloids and the surfaces of rock fractures. We focused on overall effects related to the kinetic behavior of those sorption processes. A mixed solution of cesium and clay colloids was injected into an artificially-created single fracture in a granite column. Numerical simulations were conducted to analyze the experiment results using a numerical code COLFRAC which can simulate colloid-facilitated solute transport in discretely-fractured porous media. A series of experimental and numerical analyses show that migration of cesium is facilitated by mobile colloidal particles which can sorb cesium and migrate in the fracture. The analyses also demonstrate that cesium migration is significantly enhanced if desorption of cesium from the colloids is a slow kinetic process and illustrate the importance of evaluating the parameters which describe such kinetic processes. Furthermore, radionuclide transport is likely to be retarded if mobile colloidal particles which sorb radionuclides are vigorously filtered on the fracture surfaces.

The Study of highly sensitivity technique for sodium leak detection using laser resonance ionization mass spectrometry to improve fast reactor plant safety

Aoyama, Takafumi; Ito, Chikara; Araki, Yoshio; Naito, Hiroyuki; Okazaki, Koki*; Harano, Hideki*; Watanabe, Kenichi*; Iguchi, Tetsuo*; Takegawa, Nobuyuki*; Kondo, Yutaka*

no journal, , 

no abstracts in English

The Study of highly sensitivity technique for sodium leak detection using laser resonance ionization mass spectrometry to improve fast reactor plant safety

Aoyama, Takafumi; Ito, Chikara; Araki, Yoshio; Naito, Hiroyuki; Iwata, Yoshihiro; Okazaki, Koki*; Harano, Hideki*; Watanabe, Kenichi*; Iguchi, Tetsuo*; Takegawa, Nobuyuki*; et al.

no journal, , 

no abstracts in English

Real time reconstruction of spherical tokamak plasma shape by CCS method with eddy current in QUEST

Yi, J.*; Nakamura, Kazuo*; Liu, X.*; Mitarai, Osamu*; Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Hasegawa, Makoto*; Tokunaga, Kazutoshi*; Zushi, Hideki*; et al.

no journal, , 

no abstracts in English

Changes in the dynamics of human -synuclein and its relation to propensity for amyloid fibril formation

Fujiwara, Satoru; Araki, Katsuya*; Matsuo, Tatsuhito; Yagi, Hisashi*; Yamada, Takeshi*; Shibata, Kaoru; Mochizuki, Hideki*

no journal, , 

Changes in the dynamics of human -synuclein detected by neutron scattering

Fujiwara, Satoru; Araki, Katsuya*; Matsuo, Tatsuhito; Yagi, Hisashi*; Yamada, Takeshi*; Shibata, Kaoru; Mochizuki, Hideki*

no journal, ,