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Journal Articles

Analytical technique for isotope composition of nuclear micro particles

Miyamoto, Yutaka; Suzuki, Daisuke; Tomita, Ryohei; Tomita, Jumpei; Yasuda, Kenichiro

Isotope News, (786), p.22 - 25, 2023/04

no abstracts in English

Journal Articles

Variation of crystallinity and secondary ion quantity of uranium particles with heating temperature of Sample preparation

Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Yasuda, Kenichiro; Esaka, Fumitaka; Miyamoto, Yutaka

KEK Proceedings 2022-2, p.108 - 113, 2022/11

Automated Particle Measurement (APM) is the first measurement of environmental sample for safeguard purpose. APM tells us the number of particles in sample, their enrichment and their location. Precision and accuracy of APM is easily affected by particle condition. We have investigated how influential baking temperature in sample preparation are for uranium secondary ion quantity, uranium hydride generation and particle crystallinity. Our experimental results showed that baking temperature of 800$$^{circ}$$C reduced uranium secondary ion quantity to 33% compared with baking at 350$$^{circ}$$C. Uranium hydride generation ratio of the sample baked at 850$$^{circ}$$C was also 4 times higher than the sample baked at 350$$^{circ}$$C. Baking at 850$$^{circ}$$C raised only crystallinity of uranium particles. Baking sample at too high temperature caused less uranium secondary ion generation and much more uranium hydride generation. It made precision and accuracy of APM worse. In our experiment, baking at 350$$^{circ}$$C is suitable for uranium particles in the safeguards sample.

Journal Articles

Preparation of the particles containing isotope reference uranium for the determination of the low abundant U isotope ratios

Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka

KEK Proceedings 2022-2, p.154 - 158, 2022/11

Precise determination of minor U isotopes ($$^{233}$$U and $$^{236}$$U) of particles from the safeguard environmental samples is powerful method for detecting the undeclared nuclear activities. In this study, preparation method of U particle was examined to utilize for the minor U isotope determination. The porous silica particles were used as the particle matrix and lutetium was mixed to the impregnation solution as U impregnation indicator for the particle picking. The result of the Scanning Electron Microscope indicated that the contacting the solution with Si particles overnight gently could produce the impregnated particles effectively rather than the mixing them with PFA stick.

Journal Articles

An Examination of rapid analysis of $$^{226}$$Ra in natural water samples by ICP-MS

Tomita, Jumpei; Ozawa, Mayumi; Ohara, Yoshiyuki; Miyamoto, Yutaka

KEK Proceedings 2021-2, p.130 - 134, 2021/12

no abstracts in English

Journal Articles

Optimization of SIMS-APM for high enrichment uranium particles including higher uranium hydride

Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Yasuda, Kenichiro; Esaka, Fumitaka; Miyamoto, Yutaka

KEK Proceedings 2021-2, p.146 - 150, 2021/12

no abstracts in English

Journal Articles

Age determination analysis of a single uranium particle for safeguards

Suzuki, Daisuke; Tomita, Ryohei; Tomita, Jumpei; Esaka, Fumitaka; Yasuda, Kenichiro; Miyamoto, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 328(1), p.103 - 111, 2021/04

 Times Cited Count:3 Percentile:47.54(Chemistry, Analytical)

An analytical technique was developed to determine the age of uranium particles for safeguards. After the chemical separation of uranium and thorium, the $$^{230}$$Th/$$^{234}$$U ratio was measured using single-collector inductively coupled plasma mass spectrometry and a $$^{233}$$U-based reference material comprising a certain amount of $$^{229}$$Th as a progeny nuclide of $$^{233}$$U. The results allowed us to determine the purification age of two certified materials, i.e., U-850 and U-100, which was in good agreement with the reference purification age (61 y). Moreover, the age of a single U-850 particle was determined with a difference of -28 to 2 years from the reference date.

Journal Articles

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

Sonoda, Tetsu*; Wada, Michiharu*; Tomita, Hideki*; 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:20 Percentile:83.94(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.

56 (Records 1-20 displayed on this page)