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Journal Articles

Formation process of swamp sediments of the Karako Lowland in northern Shimabara Peninsula, Western Japan

Nakanishi, Toshimichi*; Okuno, Mitsuru*; Yamasaki, Keiji*; Hong, W.*; Fujita, Natsuko; Nakamura, Toshio*; Horikawa, Yoshiyuki*; Sato, Eiichi*; Kimura, Haruo*; Tsutsumi, Hiroyuki*

Nagoya Daigaku Nendai Sokutei Kenkyu, 5, p.38 - 43, 2021/03

no abstracts in English

Journal Articles

A Geochemical approach for identifying marine incursions; Implications for tsunami geology on the Pacific coast of northeast Japan

Watanabe, Takahiro; Tsuchiya, Noriyoshi*; Yamasaki, Shinichi*; Sawai, Yuki*; Hosoda, Norihiro*; Nara, Fumiko*; Nakamura, Toshio*; Komai, Takeshi*

Applied Geochemistry, 118, p.104644_1 - 104644_11, 2020/07

 Times Cited Count:9 Percentile:65.99(Geochemistry & Geophysics)

Possible tsunami inundation areas can be predicted from the distribution of paleo tsunami deposits, which are mainly composed of marine-derived sands and muds on land. Such exotic sandy and muddy layers have been identified by multiple approaches. However, there still remain uncertainties and other useful proxies need to be investigated for the identification of tsunami deposits. Here we show the geochemical signatures of modern tsunami deposits from the Pacific coast of Northeast Japan (2011 Tohoku tsunami), as well as those paleo tsunami deposits, which were taken from the Tohoku District (Jogan, ca. 1080 calibrated ages before present [cal BP] and Yayoi, ca. 2000 cal BP). A geochemical ternary diagram (Seawater-Rock-(As+Metals)) enables the weathering trend of tsunami deposits over ca. 2000 years in the Sendai Plain in the Tohoku to be shown. In the paleo tsunami layers from the Tohoku, the Na/Ti atomic ratios markedly increased to 23.4, and the average values were 19.3$$pm$$3.0 (Jogan and Yayoi tsunami deposits), which were clearly higher than those of other layers (soil deposits, 10.3$$pm$$3.5 on average). These results show that the Na/Ti ratio is a useful indicator of marine incursions in our case. Our rapid and simple method using the Na/Ti ratio can be easily applied to the Tohoku, and it may contribute to the detection of unrecorded muddy tsunami deposits.

Journal Articles

Welding technology R&D on port joint of JT-60SA vacuum vessel

Shibama, Yusuke; Masaki, Kei; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira; Onawa, Toshio*; Araki, Takao*; Asano, Shiro*

Fusion Engineering and Design, 88(9-10), p.1916 - 1919, 2013/10

 Times Cited Count:2 Percentile:18.71(Nuclear Science & Technology)

This presentation focuses on the welding technology R&D between the JT-60SA vacuum vessel and the ports. The vacuum vessel is designed to allow port bore penetration to access the vessel inside for plasma diagnostics, and so on. There are various types of 73 ports and these are categorized by their locations; the upper/lower vertical, the upper/lower oblique, and the horizontal. Ports are onsite-welded onto the VV port stub after the assembly of the VV. This assembly sequence involves the out-vessel components such as VV thermal shield and toroidal field magnets, so that these ports welding are accessed from the inside of the vessel and limited by the internal port wall. The one of the most difficult ports are the upper vertical port with corner radius of 50 mm under narrow space, and it is necessary to clarify mobility of the weld torch head. The port weldability is discussed with the mock-up trial, which consists of the partial test pieces of the product size. The TIG welding manipulator, optimized for this R&D, is prepared by its operational simulation and examined not to interfere with the internal port wall.

Journal Articles

Fundamental welding R&D results for manufacturing vacuum vessel of JT-60SA

Asano, Shiro*; Okuyama, Toshihisa*; Onawa, Toshio*; Yanagi, Yutaka*; Ejiri, Mitsuru*; Kanahara, Toshio*; Ichihashi, Koji*; Kikuchi, Atsushi*; Mizumaki, Shoichi*; Masaki, Kei; et al.

Fusion Engineering and Design, 86(9-11), p.1816 - 1820, 2011/10

 Times Cited Count:12 Percentile:66.95(Nuclear Science & Technology)

The real vacuum vessel (VV) manufacturing of JT-60SA has started since Nov. 2009 at Toshiba. Prior to starting manufacturing, fundamental welding R&Ds had been performed by three stages. In the first stage, primary tests for screening welding method were performed. In the second stage, the trial welding for 1m-long straight and curved double shell samples were conducted. The dependences of welding quality and distortion on the welding conditions, such as arc voltage and current, setting accuracy, welding sequence, the shape of grooves, etc. were measured. In addition, welding condition with low heat input was explored. In the last stage, fabrication sequence was confirmed and established by the trial manufacturing of the 20$$^{circ}$$ upper half mock-up. This poster presents the R&D results obtained in the first and second stages.

Journal Articles

None

Masaki, Toshio; ; Kobayashi, Hiroaki; Kawamura, Kazuhiro; Igarashi, Hiroshi

NO.105 P.47-55, (105), p.47 - 55, 1998/03

None

JAEA Reports

The ninth test run of Joule-Heated cylindrical electrode melter on an engineering scale (JCEM-E9); Research report on solidification of high-level liquid waste

; ; *; *; Masaki, Toshio; Kobayashi, Hiroaki; *

PNC TN8410 98-041, 185 Pages, 1998/02

PNC-TN8410-98-041.pdf:7.51MB

The 9$$^{th}$$ test of Joule-Heated Cylindrical Electrode Melter - Engineering Scale (JCEM-E9 Test) was carried out from June to July 1996, as a part of the development program on an advanced glass melter. The principal purpose of the test was to estimate the effect of noble metal on operation of the melter with simulated high-level liquid waste. Besides, we also evaluated the basic operational characteristics with corrosion of electrodes, qualities of produced glass etc. JCEM-E is an electric glass melter with an internal electrode and an external electrode in a subsidiary furnace. The internal electrode is a rod inserted in the center of external electrode that is a cylindrical tank. The glass is melted by conducting electric current through the molten glass between the internal and external electrodes. The subsidiary furnace is composed of multi-layer refractories inside a metallic casing and is equipped with the resistance heaters. Melting surface area is 0.35 m$$^{2}$$ that i8 approximately half of 0.66 m$$^{2}$$ of TVF melter. In the test, 13 batches of glass was produced and total weight of produced glass was 3663kg. As a result, The maximum processing rate of JCEM-E with simulated HLLW including noble metals was 4.20$$sim$$5.60kg/h, and decreased to less than 80 percent compared with JCEM-E8 Test with non-noble metals HLLW. It was considered that the decrease of the rate arose from concentration of current due to non-uniform distribution of noble metals in molten glass. Judging from the balance of feed and draining, and as a consequence of the observation inside the melter after the test, the draining of noble metals from the nozzle was good. As for the quality of glass produced in the test, properties of concern were comparable with those of standard glass of TVF.

JAEA Reports

None

Kawamura, Kazuhiro; Masaki, Toshio; *; Kobayashi, Hiroaki; *; *

PNC TN8410 98-034, 110 Pages, 1998/02

PNC-TN8410-98-034.pdf:6.01MB

no

Journal Articles

Development of joule-heated cylindrical electrode melter (JCEM) to vitrify radioactive wastes

Igarashi, Hiroshi; Masaki, Toshio; Ouchi, Jin

SPECTRUM '94, 0 Pages, 1994/08

None

JAEA Reports

None

; Kobayashi, Hiroaki; Masaki, Toshio; *; Kawamura, Kazuhiro; ;

PNC TN8440 94-028, 173 Pages, 1994/06

None

JAEA Reports

None

Ouchi, Jin; Ayame, Yasuo; Terada, Akihiko; Masaki, Toshio; Kobayashi, Hiroaki; Igarashi, Hiroshi

PNC TN8410 94-219, 473 Pages, 1994/06

PNC-TN8410-94-219.pdf:8.56MB

None

Journal Articles

None

Masaki, Toshio; Igarashi, Hiroshi; Miyauchi, Tomoko*; Takahashi, Takeshi

Donen Giho, (84), p.60 - 64, 1992/12

None

Journal Articles

None

Igarashi, Hiroshi; Masaki, Toshio; Ouchi, Jin

NUC. & HAZADOUS WASTE MANAGEMENT INT. TOPICAL MEETI, , 

None

Oral presentation

Development of long-life vitrification melter, 4; Evaluation of fundamental performances of the melter

Yamashita, Teruo; Masaki, Toshio; Shiotsuki, Masao; Yamasaki, Akito*; Ito, Toshiyuki*; Ono, Isamu*; Matsumoto, Shiro*

no journal, , 

no abstracts in English

Oral presentation

Development of long-life vitrification melter, 13; Evaluation of temperature distribution of the melter

Yamashita, Teruo; Masaki, Toshio; Kojima, Keizo; Shiotsuki, Masao; Ito, Toshiyuki*; Ono, Isamu*; Matsumoto, Shiro*

no journal, , 

no abstracts in English

Oral presentation

Development of long-life vitrification melter, 14; Evaluation of temperature distribution by the small scale test melter

Yamashita, Teruo; Masaki, Toshio; Nakajima, Masayoshi; Shiotsuki, Masao; Kojima, Keizo; Toyoshima, Mikihiro; Matsumoto, Shiro*

no journal, , 

no abstracts in English

Oral presentation

Development of advanced vitrification melter, 15; Evaluation of temperature of wall by the small scale melter

Yamashita, Teruo; Masaki, Toshio; Nakajima, Masayoshi; Nakazaki, Katsutoshi; Toyoshima, Mikihiro

no journal, , 

no abstracts in English

Oral presentation

Study on Noble Metals sedimentation and viscosity of molten glass

Miyauchi, Atsushi; Nakajima, Masayoshi; Morikawa, Yo; Masaki, Toshio; Kobayashi, Hidekazu; Yamashita, Teruo; Komamine, Satoshi*; Ochi, Eiji*

no journal, , 

no abstracts in English

Oral presentation

Influence of long-term melting on the noble metals shape and glass viscosity

Morikawa, Yo; Miyauchi, Atsushi; Nakajima, Masayoshi; Masaki, Toshio; Kobayashi, Hidekazu; Yamashita, Teruo; Komamine, Satoshi*; Ochi, Eiji*

no journal, , 

no abstracts in English

Oral presentation

Fatigue behavior on welded joint for JT-60SA vacuum vessel

Yanagi, Yutaka*; Shibui, Masanao*; Kanahara, Toshio*; Mochida, Tsutomu*; Ejiri, Mitsuru*; Asano, Shiro*; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira

no journal, , 

JT-60SA Vacuum Vessel (VV) has D-shaped cross section and double-walled structure. It consists of the inner and outer wall reinforced by poloidal ribs and is made of SUS316L (Co$$<$$0.05wt%). The welding outer wall on rib (so called continuous plug) is performed from the outside of double-wall. Since it is difficult to confirm the penetration bead from the inside of double-wall, an incomplete penetration is assumed to be included in this welded joint. In this study, the fatigue test of continuous plug welded joint with an artificial incomplete penetration was performed to investigate the effect of the incomplete penetration on fatigue behavior and fatigue strength.

Oral presentation

The Millennium scale monsoon cycles recorded in a sediment core from alpine Tibetan lake

Watanabe, Takahiro; Nara, Fumiko*; Matsunaka, Tetsuya*; Minoura, Koji*; Kakegawa, Takeshi*; Yamasaki, Shinichi*; Tsuchiya, Noriyoshi*; Nakamura, Toshio*; Junbo, W.*; Liping, Z.*

no journal, , 

Understanding of past environmental and geochemical changes is significant issues to estimate global climate variation. Therefore, these changes have been studied by continuous terrestrial sediments. The high-time resolution past environmental changes, especially monsoon fluctuations, have been reported in previous studies using geochemical signatures in stalagmites from Asian caves. However, continuous climate records in Tibetan plateau have not yet been cleared, which a key area to understand mechanism of monsoon fluctuations. In this study, mean grain size and geochemical proxies from lake sediment cores from south Tibetan plateau were used for estimation of past monsoon changes during Holocene. Spectral analysis of the mean grain size in the Tibetan lake indicated 1000-1500 years climate cycles, which might be caused by the changes in solar activities. These monsoon fluctuations based on the mean grain size were also supported by geochemical proxies in this study.

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