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Journal Articles

Hydrological and climate changes in southeast Siberia over the last 33 kyr

Katsuta, Nagayoshi*; Ikeda, Hisashi*; Shibata, Kenji*; Kokubu, Yoko; Murakami, Takuma*; Tani, Yukinori*; Takano, Masao*; Nakamura, Toshio*; Tanaka, Atsushi*; Naito, Sayuri*; et al.

Global and Planetary Change, 164, p.11 - 26, 2018/05

 Times Cited Count:6 Percentile:46.34(Geography, Physical)

Paleoenvironmental and paleoclimate changes in Siberia were reconstructed by continuous, high-resolution records of chemical compositions from a sediment core retrieved from the Buguldeika Saddle, Lake Baikal, dating back to the last 33 cal. ka BP. The Holocene climate followed by a shift at ca. 6.5 cal. ka BP toward warm and dry, suggesting that the climate system transition from the glacial to interglacial state occurred. In the last glacial period, the deposition of carbonate mud from the Primorsky Range was associated with Heinrich events (H3 and H1) and the Selenga River inflow was caused by meltwater of mountain glaciers in the Khamar-Daban Range. The anoxic bottom-water during Allerod-Younger Dryas was probably a result of weakened ventilation associated with reduced Selenga River inflow and microbial decomposition of organic matters from the Primorsky Range. The rapid decline in precipitation during the early Holocene may have been a response to the 8.2 ka cooling event.

Journal Articles

Dismantlement of large fusion experimental device JT-60U

Ikeda, Yoshitaka; Okano, Fuminori; Sakasai, Akira; Hanada, Masaya; Akino, Noboru; Ichige, Hisashi; Kaminaga, Atsushi; Kiyono, Kimihiro; Kubo, Hirotaka; Kobayashi, Kazuhiro; et al.

Nihon Genshiryoku Gakkai Wabun Rombunshi, 13(4), p.167 - 178, 2014/12

The JT-60U torus was disassembled so as to newly install the superconducting tokamak JT-60SA torus. The JT-60U used the deuterium for 18 years, so the disassembly project of the JT-60U was the first disassembly experience of a fusion device with radioactivation in Japan. All disassembly components were stored with recording the data such as dose rate, weight and kind of material, so as to apply the clearance level regulation in future. The lessons learned from the disassembly project indicated that the cutting technologies and storage management of disassembly components were the key factors to conduct the disassembly project in an efficient way. After completing the disassembly project, efforts have been made to analyze the data for characterizing disassembly activities, so as to contribute the estimation of manpower needs and the radioactivation of the disassembly components on other fusion devices.

Journal Articles

Safe disassembly and storage of radioactive components of JT-60U torus

Ikeda, Yoshitaka; Okano, Fuminori; Hanada, Masaya; Sakasai, Akira; Kubo, Hirotaka; Akino, Noboru; Chiba, Shinichi; Ichige, Hisashi; Kaminaga, Atsushi; Kiyono, Kimihiro; et al.

Fusion Engineering and Design, 89(9-10), p.2018 - 2023, 2014/10

 Times Cited Count:2 Percentile:19.81(Nuclear Science & Technology)

Disassembly of the JT-60U torus was started in 2009 after 18-years D$$_{2}$$ operations, and was completed in October 2012. The JT-60U torus was featured by the complicated and welded structure against the strong electromagnetic force, and by the radioactivation due to D-D reactions. Since this work is the first experience of disassembling a large radioactive fusion device in Japan, careful disassembly activities have been made. About 13,000 components cut into pieces with measuring the dose rates were removed from the torus hall and stored safely in storage facilities by using a total wokers of 41,000 person-days during 3 years. The total weight of the disassembly components reached up to 5,400 tons. Most of the disassembly components will be treated as non-radioactive ones after the clearance verification under the Japanese regulation in future. The assembly of JT-60SA has started in January 2013 after this disassembly of JT-60U torus.

JAEA Reports

Storage management of disassembled and radioactive components of JT-60 tokamak device; Storage of radioactive components by containers

Nishiyama, Tomokazu; Miyo, Yasuhiko; Okano, Fuminori; Sasajima, Tadayuki; Ichige, Hisashi; Kaminaga, Atsushi; Miya, Naoyuki; Sukegawa, Atsuhiko; Ikeda, Yoshitaka; Sakasai, Akira

JAEA-Technology 2014-006, 30 Pages, 2014/03

JAEA-Technology-2014-006.pdf:4.87MB

JT-60 tokamak device and the peripheral equipment were disassembled so as to be upgraded to the superconducting tokamak JT-60SA. The disassembled components were stored into storage and airtight containers at the radioactive control area. The total weight and the total number of those components are about 1,100 tons and about 11,500 except for large components. Radiation measurements and records of the radioactive components were required one by one under the law of Act on Prevention of Radiation Disease Due to Radioisotopes, etc. for the control of transport and storage from the radioactive control area to the other area. The storage management of the radioactive components was implemented by establishing the work procedure and the component management system by barcode tags. The radioactive components as many as 11,500 were surely and effectively stored under the law. The report gives the outline of the storage of JT-60 radioactive components by the storage containers.

JAEA Reports

Disassembly of JT-60 tokamak device and ancillary facilities for JT-60 tokamak

Okano, Fuminori; Ichige, Hisashi; Miyo, Yasuhiko; Kaminaga, Atsushi; Sasajima, Tadayuki; Nishiyama, Tomokazu; Yagyu, Junichi; Ishige, Yoichi; Suzuki, Hiroaki; Komuro, Kenichi; et al.

JAEA-Technology 2014-003, 125 Pages, 2014/03

JAEA-Technology-2014-003.pdf:13.32MB

The disassembly of JT-60 tokamak device and its peripheral equipments, where the total weight was about 5400 tons, started in 2009 and accomplished in October 2012. This disassembly was required process for JT-60SA project, which is the Satellite Tokamak project under Japan-EU international corroboration to modify the JT-60 to the superconducting tokamak. This work was the first experience of disassembling a large radioactive fusion device based on Radiation Hazard Prevention Act in Japan. The cutting was one of the main problems in this disassembly, such as to cut the wielded parts together with toroidal field coils, and to cut the vacuum vessel into two. After solving these problems, the disassembly completed without disaster and accident. This report presents the outline of the JT-60 disassembly, especially tokamak device and ancillary facilities for tokamak device.

JAEA Reports

Disassembly of JT-60 tokamak device

Okano, Fuminori; Ikeda, Yoshitaka; Sakasai, Akira; Hanada, Masaya; Ichige, Hisashi; Miyo, Yasuhiko; Kaminaga, Atsushi; Sasajima, Tadayuki; Nishiyama, Tomokazu; Yagyu, Junichi; et al.

JAEA-Technology 2013-031, 42 Pages, 2013/11

JAEA-Technology-2013-031.pdf:18.1MB

The disassembly of JT-60 tokamak device and its peripheral equipments, where the total weight was about 6200 tons, started in 2009 and accomplished in October 2012. This disassembly was required process for JT-60SA project, which is the Satellite Tokamak project under Japan-EU international corroboration to modify the JT-60 to the superconducting tokamak. This work was the first experience of disassembling a large radioactive fusion device based on Radiation Hazard Prevention Act in Japan. The cutting was one of the main problems in this disassembly, such as to cut the wielded parts together with toroidal field coils, and to cut the vacuum vessel into two. After solving these problems, the disassembly completed without disaster and accident. This report presents the outline of the JT-60 disassembly, especially tokamak device.

Journal Articles

Recharge evaluation of northern area in Hokkaido, Japan

Ikeda, Makoto; Munakata, Masahiro; Sakai, Ryutaro; Kimura, Hideo; Jia, H.*; Matsuba, Hisashi*

Nihon Chikasui Gakkai 2011-Nen Shunki Koenkai Koen Yoshi, p.86 - 91, 2011/05

no abstracts in English

Journal Articles

Recharge evaluation using distributed tank model

Ikeda, Makoto; Munakata, Masahiro; Sakai, Ryutaro; Fuchiwaki, Hirotaka; Kimura, Hideo; Matsuba, Hisashi*

Nihon Chikasui Gakkai 2010-Nen Shuki Koenkai Koen Yoshi, p.282 - 287, 2010/11

no abstracts in English

Journal Articles

High-quality single crystal growth and physical properties in a ferromagnet UIr

Yamamoto, Etsuji; Haga, Yoshinori; Ikeda, Shugo; Matsuda, Tatsuma; Akazawa, Teruhiko*; Kotegawa, Hisashi*; Kobayashi, Tatsuo*; Onuki, Yoshichika*

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.e123 - e125, 2007/03

no abstracts in English

JAEA Reports

Development of Pu analysis in high active liquid waste (JASPAS JC-13)

; ; Jitsukata, Shu*; Kurosawa, A.; Ikeda, Hisashi

JNC TN8410 2001-017, 75 Pages, 2001/06

JNC-TN8410-2001-017.pdf:1.87MB

It has been required from IAEA to determine a small amount of plutonium in the high active liquid waste solutions (HALW) in the tokai reprocessing plant. High performance spectrophotometer (HPSP), which could be obtained lower detection limit than conventional spectrophotometer, is studied to be applied the inspection and verification analysis. The results of applicability test are described in this report, [Cold Test] Neodymium, showing an absorption peak near the absorption wavelength of plutonium (VI), was used as an alternative element to plutonium, in order to review the calculation method of the peak intensity. [Hot Test] Plutonium nitrate solution was used for the fundamental test of this method. Since the method is known to be influenced by acidity, suspended sludge and coexistent elements in a sample, each dependency was examined. It was found that measurement results varied about 14% at a nitric acid concentration of 2-4 mol/L. Sludge could be removed by filtration before the measurement. The effect of coexisting elements could be eliminated adjusting the optical balance between reference and sample beam intensity. In the case of measuring a low concentration plutonium solution, a ratio of the peak intensity to the background intensity (S/B ratio) was not enough to the measured low concentration of Plutonium. Therefore a method should be improved the S/B ratio by analyzing the obtained spectra. Data accumulation method, simple moving average method and Fourier transform analysis was tested. The results showed that a combination of the accumulated average method and the moving average method was the optimum method fbr the purpose. Linearity of the calibration curve was found between 0-11 mgPu/L. Synthetic sample solution, which simulated the actual constituents of the HALW with plutonium, showed a good linear relation at 0-11 mgPu/L. The detection limit for plutonium concentration was 0.07 mgPu/L. When the synthetic HALW solution containing plutonium was m

Journal Articles

Determination of Plutonium in High Active Liquid Waste by Spectrophotometry using Dysprosium as an Internal Standard

Kitao, Takahiko; Jitsukata, Shu*; Sato, Soichi; Ikeda, Hisashi ; Atsushi, Ishibashi,; Surugaya, Naoki

SYMPOSIUM ON SAFEGUARDS AND NUCLEAR MATERIAL MANAGEMENT, 0 Pages, 2001/00

None

Journal Articles

None

Kuno, Takehiko; ; Ikeda, Hisashi

Saikuru Kiko Giho, (9), p.57 - 63, 2000/12

None

JAEA Reports

Measurement of U and Pu concentration by X-ray fluorescence spectrometry using vertical irradiation system.

; ; ; Ikeda, Hisashi ; Jitsukata, Shu*; *

JNC TN8410 2000-022, 55 Pages, 2000/05

JNC-TN8410-2000-022.pdf:1.57MB

Measurement of U and Pu concentrations by wavelength dispersion type X-ray fluorescence spectrometry was studied. Sample holder was installed inside of glove box and other instruments, X-ray tube, monochromator and detectors were set out side of the glove box. X-rays was irradiated to sample though Be window. Fluorescent X-rays form sample were also passing though the same Be window and detected outside. Analytical conditions were optimized as follows. Sample thickness is 8 mm, which is 3ml of sample volume by the sample holder. Voltage and eurrent for X-ray tube is 50kV and 40 mA, respectively. Measurement was done twice, 60 seconds each, and averaged X-ray intensity was used to calculate elemental concentrations. Matrix correction was necessary to measure U and Pu concentration within 10% accuracy. Detection limits were calculated to 0.4 mg/L for U and 0.7mg/L for Pu. Calibration curve was liner up to 9 g/L fbr U and Pu. Two calculation methods, calibration curve method and standard addition method, were studied to measure Pu concentration in organic solution. Detection limit was 5.3 mg/L and 0.2 mg/L, respectively.

JAEA Reports

Determination of low concentration Pu by liquid scintillation and powdered solid scintillation counting method in spent fuel reprocessing solution

; ; Kurosawa, A.; Ikeda, Hisashi

JNC TN8400 99-026, 48 Pages, 1999/09

JNC-TN8400-99-026.pdf:7.97MB

Application of liquid and powdered solid scintillation alpha-counting method were studied for measurement of low concentration Pu in spent fuel reprocessing plant solution. Principle of those methods is count photons from mixture of scintillator and sample solution. Advantage of those methods is unnecessary of heating by high temperature, which is estimated to be main cause of analytical error and a fire, as the conventional ZnS(Ag) scintillation counting. Since liquid and solid scintillator are treated as a burnable waste, this method is effective concerning of reduction of wastes as well. Liquid scintillation method, whose sample volume is 0.5mL, is confirmed effectiveness for determination of Pu concentration in aqueous sample. Powdered solid scintillation method is applicable both aqueous and organic solutions. It is confirmed that this method is adopted in analysis of reprocessing solution instead of the conventional method. Pu concentration in actual reprocessing sample, 97-1 campaign, were measured by solid scintillation method. Results were agreed with those measured by the conventional method under the good precision. It is achieved sample, accurate and safety analytical procedure by applying powdered solid scintillation method.

JAEA Reports

Irradiation effects on plasma diagnostic components

Nishitani, Takeo; *; Ikeda, Yujiro; Ishitsuka, Etsuo; Kakuta, Tsunemi; Kasai, Satoshi; Kawamura, Hiroshi; Morita, Yosuke; Nagashima, Akira; Nakamichi, Masaru; et al.

JAERI-Research 98-053, 105 Pages, 1998/10

JAERI-Research-98-053.pdf:4.78MB

no abstracts in English

JAEA Reports

JASPAS JC-11(A556); Non-destructive Assay for Uranium and Plutonium in Reprocessing Input Solutions -Hybrid K-edge/XRF Densitometer- (JASPAS JC-11 Final)

Surugaya, Naoki; Abe, Katsuo; Kurosawa, A.; Ikeda, Hisashi ; Kuno, Yusuke

PNC TN8410 97-211, 156 Pages, 1997/05

PNC-TN8410-97-211.pdf:4.1MB

As a part of JASPAS programme, a non-radioactive assay system for the accountability of uranium and plutonium in input dissolver solutions of a spent fuel reprocessing plant, called Hybrid K-edge/XRF Densitometer, has been developed at the Tokai Reprocessing plant (TRP) since 1991. The instrument is the one of the hybrid type combined K-edge densitometry (KED) and X-ray fluorescence (XRF) analysis. The KED is used to determine the uranium concentration and the XRF is used to determine the U/Pu ratio. These results give the plutonium concentration in consequence. It is considered that the instrument has the capability of timely on-site verification for input accountancy. The instrument had been installed in the analytical hot cell at the TRP and the experiments comparing with Isotope Dilution Mass Spectrometry (IDMS) method have been carried out. As the results of measurements for the actual input solutions in the acceptance and performance tests, it was typically confirmed that the precision for determining uranium concentration by the KED was within 0.2%, whereas the XRF for Plutonium performed within 0.7%. This final report summarizes the design information and performance data so as to end the JASPAS programme.

JAEA Reports

Irradiation tests on diagnostics components for ITER in 1995

Nishitani, Takeo; *; Ikeda, Yujiro; Ishitsuka, Etsuo; Kakuta, Tsunemi; Kasai, Satoshi; Kawamura, Hiroshi; Maekawa, Fujio; Morita, Yosuke; Nagashima, Akira; et al.

JAERI-Tech 96-040, 22 Pages, 1996/10

JAERI-Tech-96-040.pdf:0.85MB

no abstracts in English

JAEA Reports

None

; *; Ikeda, Hisashi ; Kaminaga, Kazuhiro; ; ; Kuno, Yusuke

PNC TN8410 96-266, 67 Pages, 1996/05

PNC-TN8410-96-266.pdf:2.57MB

None

Journal Articles

None

; Yamada, Keiji; ; Ikeda, Hisashi ; Kuno, Yusuke

Donen Giho, (94), p.91 - 94, 1995/06

None

JAEA Reports

None

; ; Sugiyama, Toshihide; Ikeda, Hisashi ; ; ;

PNC TN8410 91-169, 166 Pages, 1991/05

PNC-TN8410-91-169.pdf:4.56MB

None

27 (Records 1-20 displayed on this page)