Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
-XRD with synchrotron radiationMotai, Satoko*; Mukai, Hiroki*; Watanuki, Tetsu; Owada, Kenji; Fukuda, Tatsuo; Machida, Akihiko; Kuramata, Chisaki*; Kikuchi, Ryosuke*; Yaita, Tsuyoshi; Kogure, Toshihiro*
Journal of Mineralogical and Petrological Sciences, 111(5), p.305 - 312, 2016/10
Times Cited Count：16 Percentile：51.74(Mineralogy)no abstracts in English
Takeda, Takeshi; Owada, Akihiko; Nakamura, Hideo
Experimental Thermal and Fluid Science, 51, p.112 - 121, 2013/11
Times Cited Count：12 Percentile：48.9(Thermodynamics)Takemura, Kenichi*; Watanuki, Tetsu; Owada, Kenji; Machida, Akihiko; Omura, Ayako*; Aoki, Katsutoshi
Journal of Physics; Conference Series, 215, p.012017_1 - 012017_4, 2010/03
Times Cited Count：17 Percentile：97.27(Instruments & Instrumentation)Powder X-ray diffraction experiments have been done on Ne up to 237 GPa at room temperature. Ne remains in the fcc phase up to the highest pressure. In order to observe the weak 200 reflection at ultrahigh pressure we have used the tube-cross slit at the exit side of X-rays, which effectively reduced the scattered X-rays by the diamond anvil. The lattice parameters obtained from the 111 and 200 reflections significantly differ each other, implying the existence of sizable uniaxial stress in Ne at ultrahigh pressure.
Kamiwaki, Tadayoshi; Owada, Akihiko; Takeda, Takeshi; Nakamura, Hideo
JAEA-Testing 2008-006, 77 Pages, 2008/07
JAEA-Testing-2008-006.pdf:6.32MB
Non-condensable gas for the pressurization of accumulator (ACC) tanks of emergency core cooling system may flow into the primary system during loss-of-coolant accidents (LOCAs) in a pressurized water reactor (PWR) after the ACC coolant injection is completed. Since the non-condensable gas may travel to and accumulates in steam generators (SGs) U-tubes, primary cooling and depressurization via SG secondary-side depressurization would become ineffective because of the degradation of condensation heat transfer in SG U-tubes. Since quantitative measurement of gas concentration is necessary to clarify the influences of non-condensable gas on the depressurization in ROSA/LSTF experiments that simulate PWR LOCAs and transients, an apparatus using a Zirconia oxygen sensor has been developed to directly measure the gas concentration in steam by introducing air as the non-condensable gas for the ACC pressurization. This apparatus is improved and applied to LSTF experiments where the gas concentration is measured directly in vessel upper head where gas may pass through with steam and in SG outlet plenum where gas accumulates. This report describes the improvement of the apparatus and the results of oxygen gas measurement characterization tests and the LSTF secondary-side depressurization experiments.
Aso, Naofumi*; Owada, Kenji; Watanuki, Tetsu; Machida, Akihiko; Omura, Ayako; Inami, Toshiya; Homma, Yoshiya*; Shiokawa, Yoshinobu*; Hirota, Kazuma*; Sato, Noriaki*
Journal of the Physical Society of Japan, 75(Suppl.), p.88 - 90, 2006/08
no abstracts in English
Takemoto, Masafumi; Nakamura, Hideo; Owada, Akihiko; Osaki, Hideki
JAEA-Research 2006-009, 48 Pages, 2006/03
JAEA-Research-2006-009.pdf:3.8MB
Nitrogen (N)gas used for the pressurization of accumulator (ACC) tanks may flow into the PWR primary system during LOCAs after the ACC coolant injection is completed. Since N gas may travel to and accumulates in reactor vessel top and U-tubes in steam generators (SGs), primary cooling and depressurization via SG secondary-side depressurization would become ineffective because of the degradation of condensation heat transfer in SG U-tubes. Quantitative measurement of gas accumulation is necessary to clarify the influences of gas onto such degradation in the heat transfer and thus the primary depressurization. However, direct measurement method of non-condensable gas concentration in steam has not been established. An apparatus to directly measure gas concentration in high-temperature steam was developed to measure gas concentration in vessel upper head and SG U-tubes during LOCA experiments using ROSA/LSFT. The developed apparatus is primarily composed of zirconia oxygen sensor and turbine meter, enabling to deal with small amount of steam-gas mixture at high temperature when air is used to pressurize ACC tanks instead of N gas. This report describes the developed apparatus and its operation method with several test results for the confirmation of oxygen gas measurement capability and applicability of the apparatus to the ROSA/LSTF experiments.
Takei, Akihiko*; Owada, Hitoshi*; Fujita, Hideki*; Negishi, Kumi*; Hibiya, Keisuke*; Yokozeki, Kosuke*; Watanabe, Kenzo*
JNC TJ8400 2003-047, 120 Pages, 2003/02
JNC-TJ8400-2003-047.pdf:4.46MB
We acquired the water permeation properties and also mechanical characteristics of the altered specimen that produced by permeation or immersing as the fundamental data.
Takei, Akihiko*; Owada, Hitoshi*; Fujita, Hideki*; Negishi, Kumi*; Hibiya, Keisuke*; Yokozeki, Kosuke*; Watanabe, Kenzo*
JNC TJ8400 2003-046, 282 Pages, 2003/02
JNC-TJ8400-2003-046.pdf:8.26MB
We acquired the water permeation properties and also mechanical characteristics of the altered specimen that produced by permeation or immersing as the fundamental data.
Takei, Akihiko*; Owada, Hitoshi*; Fujita, Hideki*; Negishi, Kumi*
JNC TJ8400 2003-042, 67 Pages, 2003/02
TRU waste includes various chemical compounds such as nitrates. The influence of the chemical compounds on the performance of the barrier system should be estimated. In this study, we estimated the influence of sodium nitrate and also that of the chemical compounds derived from the sodium nitrate to the degradation of the cementitious material. 1) Evaluation of the influence of nitrate ion on the alteration of the cementitious material Alteration of characteristics of cementitious material was evaluated by the water permeation test using sodium nitrate solution. The calcium concentration of sodium nitrate solution permeated sample was higher than that of blank. The result indicates that sodium nitrate solution will accelerate the alteration of cementitious material. the permeation test was continued by using the ion-exchanged water as the permeation-water. As the results, the chemical and physical characteristics of the samples approached to those of blanks.2) Evaluation of the influence of ammonia on the alteration of the cementitious material Alteration of characteristics of cementitious material in nitrate and ammonia solution was evaluated by the water permeation test using 1mol/liter-sodium-nitrate and 0.5mol/liter-ammonia solution (denoted as NH-solution in the following). The calcium concentration of NH-solution permeated sample was higher than that of blank and the value of the calcium concentration was almost the same as that of the sodium nitrate solution case. The alteration range by the calcium leaching of the solid phase of the NH-solution case shows similar trend to that of the sodium nitrate solution case. The acceleration of the calcium dissolution was considered from this result. And the change of the water-permeability indicated the same trend with sodium-nitrate-solution case. From these results we confirmed that ammonia solution would not influence the alteration of cementitious solution.
Takei, Akihiko*; Owada, Hitoshi*; Fujita, Hideki*; Negishi, Kumi*
JNC TJ8400 2003-041, 152 Pages, 2003/02
JNC-TJ8400-2003-041.pdf:7.93MB
TRU waste includes various chemical compounds such as nitrates. The influence of the chemical compounds on the performance of the barrier system should be estimated. In this study, we estimated the influence of sodium nitrate and also that of the chemical compounds derived from the sodium nitrate to the degradation of the cementitious material. 1) Evaluation of the influence of nitrate ion on the alteration of the cementitious material Alteration of characteristics of cementitious material was evaluated by the water permeation test using sodium nitrate solution. The calcium concentration of sodium nitrate solution permeated sample was higher than that of blank. The result indicates that sodium nitrate solution will accelerate the alteration of cementitious material. the permeation test was continued by using the ion-exchanged water as the permeation-water. As the results, the chemical and physical characteristics of the samples approached to those of blanks. 2) Evaluation of the influence of ammonia on the alteration of the cementitious material Alteration of characteristics of cementitious material in nitrate and ammonia solution was evaluated by the water permeation test using 1mol/liter-sodium-nitrate and 0.5mol/liter-ammonia solution (denoted as NH-solution in the following). The calcium concentration of NH-solution permeated sample was higher than that of blank and the value of the calcium concentration was almost the same as that of the sodium nitrate solution case. The alteration range by the calcium leaching of the solid phase of the NH-solution case shows similar trend to that of the sodium nitrate solution case. The acceleration of the calcium dissolution was considered from this result. And the change of the water-permeability indicated the same trend with sodium-nitrate-solution case. From these results we confirmed that ammonia solution would not influence the alteration of cementitious solution.
Watanuki, Tetsu; Machida, Akihiko; Omura, Ayako; Aoki, Katsutoshi; Owada, Kenji; Sato, Taku*; Tsai, A. P.*
no journal, ,
no abstracts in English
Nakamura, Hideo; Owada, Akihiko; Osaki, Hideki
no journal, ,
no abstracts in English
Watanuki, Tetsu; Machida, Akihiko; Omura, Ayako; Aoki, Katsutoshi; Owada, Kenji; Sato, Taku*; Tsai, A. P.*
no journal, ,
no abstracts in English
Watanuki, Tetsu; Machida, Akihiko; Omura, Ayako; Aoki, Katsutoshi; Owada, Kenji; Sato, Taku*; Tsai, A. P.*
no journal, ,
no abstracts in English
Watanuki, Tetsu; Machida, Akihiko; Omura, Ayako; Aoki, Katsutoshi; Owada, Kenji; Sato, Taku*; Tsai, A. P.*
no journal, ,
no abstracts in English
Owada, Akihiko
no journal, ,
no abstracts in English
