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Journal Articles

Development of a resonant laser ionization gas cell for high-energy, short-lived nuclei

Sonoda, Tetsu*; Wada, Michiharu*; Tomita, Hideo*; Sakamoto, Chika*; Takatsuka, Takaaki*; Furukawa, Takeshi*; Iimura, Hideki; Ito, Yuta*; Kubo, Toshiyuki*; Matsuo, Yukari*; et al.

Nuclear Instruments and Methods in Physics Research B, 295, p.1 - 10, 2013/01

 Times Cited Count:19 Percentile:12.05(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

Development of fuel microspheres fabrication by the external gelation process

Tomita, Yutaka; Morihira, Masayuki; Tamaki, Yoshihisa*; Nishimura, Kazuhisa*; Shoji, Shuichi*; Kihara, Yoshiyuki; Kase, Takeshi; Koizumi, Tsutomu

JAEA-Research 2006-088, 95 Pages, 2007/01

JAEA-Research-2006-088.pdf:23.02MB

JAEA has developed sphere-pac fuels in the feasibility study on commercialized FBR cycle systems as one of the candidates for low decontamination TRU fuels. Optimization of the fabrication condition for coarse spheres, development of an improved external gelation process, and examination of peculiar problems for the low decontamination fuel were carried out in Phase II. The results are shown as follows. (1) Fabrication condition of coarse spheres was optimized. (2) Feasibility of the improved external gelation process was confirmed. (3) Rare earth elements did not bring any problem for the characteristic of spheres and fabrication condition. (4) Radiation resistant data of the feed solution was acquired. Results of tests show the feasibility of the external gelation process for the low decontamination TRU fuel microsphere fabrication.

Journal Articles

Fuel microsphere fabrication tests for sphere-pac fuel by the external gelation process

Tomita, Yutaka; Morihira, Masayuki; Kihara, Yoshiyuki; Tamaki, Yoshihisa*

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 4 Pages, 2005/10

High economic competitiveness and low environmental impact are required for advanced FBR cycle systems. Sphere-pac fuel has been considered as promising fuel systems, due to its inherent advantage in remote operation, dustfree fuel fabrication process and cost reduction. Japan Nuclear Cycle Development Institute (JNC) has been investigated the external gelation process for sphere-pac fuel. In this report, the result of the sphere fabrication test by the external gelation process is reported.

Journal Articles

Fabrication of Sphere-pac Fuel and Vipac Fuel for Irradiation Tests (Collaboration Project among JNC, PSI and NRG)

Tomita, Yutaka; Shigetome, Yoshiaki; Kihara, Yoshiyuki

Saikuru Kiko Giho, (24), p.1 - 10, 2004/00

JNC has carried out the joint research project with PSI in Switzerland and NRG in Netherlands.In this project, three types of fuel segments (sphere-pac segments, vipac segments and pellet segments) were fabricated by PSI. They have been irradiated under same irradiation condition to compare their performances in the High Flux Reactor. This report describes the fabrication of sphere-pac segments and vipac segments for irradiation tests.

Oral presentation

Development on the purification technology in crystallization process, 3; Generation experiments of cesium plutonium nitrate

Nakahara, Masaumi; Tomita, Yutaka; Nomura, Kazunori; Washiya, Tadahiro

no journal, , 

Concerning the purification technology of UNH crystallization, cesium plutonium nitrate was obtained and was estimated by colorimetry, XRD, TG data. These experiments show cesium plutonium nitrate product increases with nitric acid concentration in the solution. This complex of XRD patterns was almost agreed with Cs$$_{2}$$U(NO$$_{3}$$)$$_{6}$$ of that. When Cs$$_{2}$$Pu(NO$$_{3}$$)$$_{6}$$ is heated for short periods, no change occurs up to 100 degrees C, after plutonium is oxidized to Cs$$_{2}$$PuO$$_{2}$$(NO$$_{3}$$)$$_{4}$$ above 245 degrees C. This observed mass loss step for TG curve of cesium plutonium nitrate was about 10%.

Oral presentation

Fundamental test of crystallization process; Evaluation of U solubility in solution of irradiated fuel

Kaji, Naoya; Nakahara, Masaumi; Nakamura, Kazuhito; Shibata, Atsuhiro; Tomita, Yutaka; Washiya, Tadahiro; Kitajima, Takafumi; Koizumi, Tsutomu

no journal, , 

Solubility obtained from the latest crystallization tests using irradiated fuel and the tests implemented before using U or Pu/U are compared with the data showed by Hart. Based on the result, availability of the data to estimate crystallization ratio is considered.

Oral presentation

Dissolution behavior of the irradiated fast reactor fuel powder; Influence of particle size

Hinai, Hiroshi; Tomita, Yutaka; Nomura, Kazunori; Oyama, Koichi; Kitajima, Takafumi; Koizumi, Tsutomu

no journal, , 

no abstracts in English

Oral presentation

Compensation of higher order dispersion on idler pulse compression scheme, 1; Phase measurement of interacting pulses on OPA

Akahane, Yutaka; Tomita, Hitoshi*; Ogawa, Kanade; Nishioka, Hajime*; Yamakawa, Koichi

no journal, , 

Spectral phases of interacting (signal, idler, pump) pulses on optical-parametric amplification process were measured, aimed for compensating higher order dispersion on compressed idler pulses by phase modulation on pump pulses in optical-parametric chirped-pulse amplification. An wide-time-range spectral-shearing interferometry developed very recently was applied to these phase measurement, which is capable for measuring picosecond chirped pulses unsuitable for SPIDER phase measurement formerly. In the measurement, some variations of spectral dispersions on idler pulses caused by phase modulation on pump pulses were observed, which enables us to control spectral dispersions of idler pulse by manipulating spectral phases of pump pulses.

Oral presentation

Development of robust intense femtosecond laser with positive dispersive media for both pulse stretcher and compressor

Akahane, Yutaka; Ogawa, Kanade; Tomita, Hitoshi*; Nishioka, Hajime*; Yamakawa, Koichi

no journal, , 

We have proposed and demonstrated a novel chirped-pulse amplification (CPA) scheme which idler pulses in optical-parametric chirped-pulse amplification have been compressed with an identical positive dispersive media as signal pulse stretcher. With this idler compression scheme simple, robust and efficient CPA laser can be realized for industrial applications. In the demonstration experiment, sub-100 fs compressed idler pulses successfully obtained.

Oral presentation

Station operation just after big earthquake in RN38, Takasaki, Japan

Kumata, Masahiro; Tomita, Yutaka

no journal, , 

A big earthquake occured in the eastern Japan on March 11, 2011. Operation and maintenance activities just after the big earthquake in RN38, Takasaki, Japan would be presented.

Oral presentation

Compensation of higher order dispersion on idler pulse compression scheme, 2; Idler dispersion compensation with pump phase modulation

Akahane, Yutaka; Tomita, Hitoshi*; Ogawa, Kanade; Nishioka, Hajime*; Yamakawa, Koichi

no journal, , 

For generation of intense few-cycle laser pulse with our idler pulse compression scheme, we have now been studying residual high-order dispersion compensation of idler pulses with pump phase modulation. The pump pulse has a narrow bandwidth with respect to signal or idler pulses, which you can easily control the pump phase by spatial light modulator or other conventional devices. And once a proper phase modulation is fixed, you can apply the modulation by some robust device such as such fiber Bragg grating or volume Bragg grating in practical use. From the first phase measurement of OPA interacting pulses, we have found that the sign of the 3rd order dispersion of the idler pulse have been inverted from the signal one and the sign of 4th order have not been inverted, which had not been expected from theory without considering the effect from pump phase modulation.

Oral presentation

SAUNA system upgrade for certification of the Takasaki IMS station

Tomita, Yutaka; Kumata, Masahiro; Wakabayashi, Shuji; Kijima, Yuichi; Yamamoto, Yoichi; Oda, Tetsuzo

no journal, , 

Oral presentation

Chemical state analysis of individual uranium particles with electron backscatter diffraction

Esaka, Fumitaka; Yomogida, Takumi; Tomita, Ryohei; Miyamoto, Yutaka

no journal, , 

Chemical state analysis is important to elucidate the origin of particles and its effect on the environment. However, the analysis is difficult because the amounts of elements in individual particles are considerably small. In the present study, electron backscatter diffraction (EBSD) is applied to the chemical state analysis of individual uranium particles. As a result, uranium particles with diameters of 1$$mu$$m were able to be measured and clear electron backscatter patterns were observed. In addition, the patterns of UO$$_{2}$$ particles were distinguished from those of U$$_{3}$$O$$_{8}$$ particles.

Oral presentation

The Determination of uranium ratios in individual environmental particles

Tomita, Ryohei; Esaka, Fumitaka; Miyamoto, Yutaka

no journal, , 

In the previous study, we developed a combination method of particle manipulation and secondary ion mass spectrometry (SIMS) for removing the interferences from other elements in other particles. Since the particles were selected randomly and manipulated, it caused the problem not to cover the range of $$^{235}$$U/$$^{238}$$U isotope ratio in the sample. In this study, we improved the procedure of analyzing uranium isotope ratios in individual particles by SIMS to cover the range of $$^{235}$$U/$$^{238}$$U in the sample.

Oral presentation

Detailed analysis of individual uranium particles in environmental sample by SIMS and pre-screening measurement introduced into the analysis procedure

Tomita, Ryohei; Esaka, Fumitaka; Miyamoto, Yutaka

no journal, , 

In the previous study, we developed a combination method of individual uranium particle manipulation in scanning electron microscope (SEM) and secondary ion mass spectrometry (SIMS) for removing the interferences from other elements in other particles. Since the particles were selected randomly and manipulated, it caused the problem not to cover the range of $$^{235}$$U/$$^{238}$$U isotope ratio in the sample. In this study, we introduced pre-screening measurement into the procedure of analyzing uranium isotope ratios in individual particles by SIMS to cover the range of $$^{235}$$U/$$^{238}$$U in the sample.

Oral presentation

JAEA's recent activities related to CTBT verification regime

Yamamoto, Yoichi; Kijima, Yuichi; Tomita, Yutaka

no journal, , 

This presentation summarizes JAEA's recent activities related to CTBT verification regime. To establish the global verification regime of CTBT for the nuclear tests, JAEA has been operating provisionally three facilities (two monitoring stations and one radionuclide laboratory) of the CTBT international monitoring system and a national data center for radionuclide monitoring. For the 6th nuclear test conducted by North Korea in September 2017, JAEA reported the analysis and evaluation results of data observed at the CTBT radionuclide monitoring stations to the national government etc. in a timely manner and thereby contributed to the evaluation by the national government based on the CTBT operation system in Japan. For the purpose of strengthening CTBTO's detection capability for nuclear tests, JAEA started new noble gas joint measurement project with CTBTO in Horonobe (Hokkaido) and Mutsu (Aomori) based on the Japanese government contribution in 2017.

Oral presentation

Japan Atomic Energy Agency's efforts to the CTBT verification regime

Yamamoto, Yoichi; Kijima, Yuichi; Tomita, Yutaka

no journal, , 

As a member of the CTBT National Operation System of Japan (NOSJ), JAEA monitors and evaluates radionuclides derived from nuclear tests. For this purpose, Takasaki and Okinawa radionuclide stations, Tokai radionuclide laboratory, and a national data center already were put in place and have been operated. This presentation introduces outline of NOSJ and each facility, the response to a nuclear test event, JAEA's recent activities etc.

Oral presentation

Status report on Japanese NDC-2; current status of Xenon joint measurement project at Horonobe and Mutsu

Yamamoto, Yoichi; Kijima, Yuichi; Tomita, Yutaka

no journal, , 

Based on repeated DPRK's nuclear tests, the Japanese government contributed funds for the noble gas measurement project in February 2017 for the purpose of strengthening CTBTO's detection capability for nuclear tests. The CTBTO decided to conduct measurements in Hokkaido and Tohoku regions of Japan for the time being, and to enhance JAEA with experiences and performance of measurements in Japan as the responsible organization. In response to this, the JAEA has installed two mobile noble gas measurement systems at Horonobe, Hokkaido and JAEA Ohminato site in Mutsu, Aomori, and been carrying out the joint measurement project with the CTBTO. The current status of this project will be presented.

Oral presentation

ATM analysis results on radioxenons detected in Japan by JAEA/NDC

Kijima, Yuichi; Yamamoto, Yoichi; Tomita, Yutaka

no journal, , 

Using the contribution from the Japanese government to the CTBTO for the purpose of strengthening of the CTBTO's detection capability for nuclear tests, the JAEA installed the Transportable Xenon Laboratories (TXLs) in collaboration with the CTBTO at Horonobe, Hokkaido and Mutsu, Aomori, and has been measuring radioxenon since 2018. Therefore, the measurements of radioxenon in Japan for monitoring nuclear tests are currently conducted at total 3 measuring points (Horonobe TXL, Mutsu TXL and Takasaki IMS station). In the past measurement results, the radioxenon isotopes with activity concentration above the background level were detected at these measuring points. The JAEA/NDC carried out the ATM analyses for the investigation of an emission source of the radioxenon isotopes for some detection cases. We report the measurement results of radioxenon and the ATM analysis results.

Oral presentation

Importance of noble gas monitoring in CTBT verification technology and observation results in Takasaki radionuclide monitoring station

Yamamoto, Yoichi; Kijima, Yuichi; Tomita, Yutaka

no journal, , 

Radionuclide monitoring is the only way to judge whether the target explosion event was a nuclear test. Among the radionuclides produced by the nuclear explosion, the noble gases are particularly important because they are inert and more likely to leak to the ground rather than other substances in an underground nuclear test. Only 4 radioxenon isotopes as the noble gases are monitored for the CTBT verification. It was after the first nuclear test of North Korea in October 2006, when a radioxenon monitoring system installed at the Takasaki radionuclide monitoring station in Japan and the radioxenon monitoring has been carried out since January 2007. We report on the past observation results of the radioxenon at the Takasaki radionuclide monitoring station and the characteristics of radioxenon background.

29 (Records 1-20 displayed on this page)