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Journal Articles

Present status and issues of dosimetry for the lens of the eye at the MOX-fuel plant

Yamazaki, Takumi; Takada, Chie; Tsujimura, Norio; Okada, Kazuhiko

Hoken Butsuri, 52(3), p.167 - 170, 2017/09

At the JAEA MOX Fuel Facilities, a worker engaged in glove box operations uses two personal dosemeters, one worn on the trunk under a protective apron and the other at the collar over the apron. The recorded lens of the eye dose is based on the photon dose measured by the collar dosemeter plus the neutron dose measured by the under-apron dosemeter.

Journal Articles

The Evaluation of the 0.07 mm and 3 mm dose equivalent with a portable beta spectrometer

Hoshi, Katsuya; Yoshida, Tadayoshi; Tsujimura, Norio; Okada, Kazuhiko

JPS Conference Proceedings (Internet), 11, p.070009_1 - 070009_6, 2016/11

Beta spectra of various nuclide species were measured by commercially available compact spectrometer. The shape of spectra obtained from the spectrometer approximately agreed with that of theoretical spectra. The beta dose equivalent at any depths has been able to be obtained as a product of measured pulse height spectra and appropriate conversion coefficients of ICRP Publ. 74. The dose rates evaluated from the spectra were comparable to the reference dose rates of standard beta calibration sources. And, we were able to determine the dose equivalent with relative error of indication of 10% without the complicated correction.

Journal Articles

Structural analysis for assembly by integrating parts

Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Okada, Tatsuo*; Tsuruta, Osamu*; Sawa, Kazuhiro; Iigaki, Kazuhiko

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 9 Pages, 2014/07

Almost all industrial products are assembled from multiple parts. A nuclear facility is a large structure consisting of more than 10 million components. This paper discusses a method to analyze an assembly by gathering data on its component parts. Gathered data on component may identify ill conditioned meshes for connecting surfaces between components. These ill meshes are typified by nodal point disagreement in finite element discretization. A technique to resolve inconsistencies in data among the components is developed. By using this technique, structural analysis for an assembly can be carried out, and results can be obtained by the use of supercomputers, such as the K computer. Numerical results are discussed for components of the High Temperature Engineering Test Reactor.

Journal Articles

A Quake-proof analysis for a plant as an assembly in the next generation

Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Okada, Tatsuo; Tsuruta, Osamu; Sawa, Kazuhiro; Iigaki, Kazuhiko

Tabo Kikai, 42(5), p.332 - 338, 2014/05

K computer is one of the highest performance computers in the world. This paper discusses one of R&D issues in K computer national project. Industrial products are an artifact, which are assembly consisting of simple components more than at least two regardless of the big products and small products. In the nuclear industry, the facilities are large structures consisting of over 10 millions of components, since they are engaged with the highest technology and for safety sake. This paper introduces a method to analyze an assembly by gathering its components data. In the manner of gathering components data, it is raised many issues to concern among components. It is developed a technique to solve the inconsistent data among the components. By using this technique, a structural analysis for an assembly is done by using K computer. Numerical results are presented in the case of analysis for High Temperature engineering Test Reactor's components.

Journal Articles

Real-time X-ray diffraction of metastable phases during solidification from the undercooled LuFeO$$_{3}$$ melt by two-dimensional detector at 1 kHz

Kumar, M. V.*; Kuribayashi, Kazuhiko*; Nagashio, Kosuke*; Ishikawa, Takehiko*; Okada, Jumpei*; Yu, J.*; Yoda, Shinichi*; Katayama, Yoshinori

Applied Physics Letters, 100(19), p.191905_1 - 191905_4, 2012/05

 Times Cited Count:2 Percentile:9.6(Physics, Applied)

${it In-situ}$ identification of metastable phases formed from the undercooled LuFeO$$_{3}$$ melt under controlled oxygen partial pressure $$P$$o$$_{2}$$ was studied by X-ray diffraction measurements at a synchrotron radiation source. Real-time observation of the formation and growth of individual phases during the single recalescence of Lu$$_{3}$$Fe$$_{2}$$O$$_{7}$$ and LuFe$$_{2}$$O$$_{4}$$ phases at $$P$$o$$_{2}$$ of 1$$times$$10$$^{3}$$ Pa has been revealed by a high speed imaging system at 1 kHz. The obtained diffraction pattern of the metastable phase in the LuFeO$$_{3}$$ system was consistent with that of the metastable and stable phases reported in the Lu-Fe-O system.

Journal Articles

Observation of fast positron diffraction from a Si(111)7$$times$$7 surface

Kawasuso, Atsuo; Fukaya, Yuki; Hayashi, Kazuhiko; Maekawa, Masaki; Ishimoto, Takayuki*; Okada, Sohei; Ichimiya, Ayahiko*

Materials Science Forum, 445-446, p.385 - 389, 2004/02

We so far discovered the total reflection and the first Bragg peak in reflection high-energy positron diffraction (RHEPD). However, the fractional order diffractions from reconstructed surfaces have been eluded from the observation. We therefore attempted to get RHEPD patterns from a Si-7$$times$$7 surface. Consequently, the 1/7, 2/7 and 3/7 diffraction rings due to Si(111)-7$$times$$7 reconstruction were clearly found in addition to the zeroth and the first Laue zones. The specular intensity was measured as a function of glancing angle. A small structure was found in the total reflection region. The small structure was attributed to the interference of positron wavefunction because of adatoms. However, the overall intensity profile was not well reproduced using a model already determined in the electron diffraction studies. To reproduce the obtained intensity profile, we may need to modify the vertical positions of the topmost surface and/or the absorption potential due to inelastic scattering processes.

Journal Articles

Si(111)-7$$times$$7 surface probed by reflection high-energy positron diffraction

Kawasuso, Atsuo; Fukaya, Yuki; Hayashi, Kazuhiko; Maekawa, Masaki; Okada, Sohei; Ichimiya, Ayahiko

Physical Review B, 68(24), p.241313_1 - 241313_4, 2003/12

 Times Cited Count:25 Percentile:73.58(Materials Science, Multidisciplinary)

We report the first observation of reflection high-energy positron diffraction from a $$7times7$$ reconstructed Si(111) surface with an well-collimated 20 kV positron beam. The diffraction pattern clearly exhibited the 1/7-th to 3/7-th order Laue zones in addition to the zero-th and first Laue zones. From the dynamical calculation of the rocking curve in the total reflection region, the vertical position of adatom layer was determined to be 1.52 ${AA}$ relative to the stacking fault layer. This value is greater than that predicted in the first principles study suggesting a significant outward relaxation of adatoms.

Journal Articles

Design study on Reduced-Moderation Water Reactor (RMWR)

Okubo, Tsutomu; Iwamura, Takamichi; Yamamoto, Kazuhiko*; Okada, Hiroyuki*

Nihon Kikai Gakkai Dai-8-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.571 - 574, 2002/00

Based on the experienced light water reactor technology, conceptual design studies on advanced water-cooled reactors have been performed. They are named “Reduced-Moderation Water Reactor" (RMWR) with the high conversion ratio more than 1.0 and the negative void reactivity coefficients. Several concepts have been successfully established for them based on the neutronics calculations. Based on these concepts, detailed investigations on such as plutonium multiple recycling and control rod planning have been performed as well as improvement on core performances. Through these detailed core design investigation, the feasibility of those designs has been confirmed step by step.

Journal Articles

Critical heat flux experiment for Reduced-Moderation Water Reactor (RMWR)

Kureta, Masatoshi; Akimoto, Hajime; Yamamoto, Kazuhiko*; Okada, Hiroyuki*

Proceedings of International Congress on Advanced Nuclear Power Plants (ICAPP) (CD-ROM), 7 Pages, 2002/00

no abstracts in English

Journal Articles

Advanced concept of Reduced-Moderation Water Reactor (RMWR) for plutonium multiple recycling

Okubo, Tsutomu; Takeda, Renzo*; Iwamura, Takamichi; Yamamoto, Kazuhiko*; Okada, Hiroyuki*

Proceedings of International Conference on Back-End of the Fuel Cycle: From Research to Solutions (GLOBAL 2001) (CD-ROM), 7 Pages, 2001/09

An advanced water-cooled reactor concept named the Reduced-Moderation Water Reactor (RMWR) has been proposed to attain a high conversion ratio more than 1.0 and to achieve the negative void reactivity coefficient. At present, several types of design concepts satisfying both the design targets have been proposed based on the evaluation for the fuel without fission products and minor actinides. In this paper, the feasibility of the RMWR core is investigated and confirmed for the plutonium multiple recycling under advanced reprocessing schemes with low decontamination factors as proposed for the FBR fuel cycle.

Oral presentation

Design of a D$$_{2}$$O-moderated $$^{241}$$Am-Li neutron calibration field

Hoshi, Katsuya; Yoshida, Tadayoshi; Tsujimura, Norio; Okada, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

Study of method of measurement of the $$beta$$-ray 3mm dose equivalent and protection measures of the lens of eyes, 2; TL dosimeter

Yamazaki, Takumi; Takimoto, Misaki; Suga, Takumi; Hoshi, Katsuya; Yoshida, Tadayoshi; Takada, Chie; Tsujimura, Norio; Okada, Kazuhiko; Ishikawa, Hisashi

no journal, , 

no abstracts in English

Oral presentation

Study of method of measurement of the $$beta$$-ray 3mm dose equivalent and protection measures of the lens of eyes, 1; Ionization chamber

Takimoto, Misaki; Yamazaki, Takumi; Imahashi, Atsushi; Hoshi, Katsuya; Kawasaki, Takashi; Yoshida, Tadayoshi; Takada, Chie; Tsujimura, Norio; Okada, Kazuhiko; Ishikawa, Hisashi

no journal, , 

no abstracts in English

Oral presentation

Development of a deuterium oxide-moderated $$^{241}$$Am-Li neutron field to simulate spent nuclear fuel shipping cask spectra

Hoshi, Katsuya; Yoshida, Tadayoshi; Tsujimura, Norio; Okada, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

Determination of neutron emission rate associated with the replacement of Californium-252 neutron source at Nuclear Fuel Cycle Engineering Laboratories

Hoshi, Katsuya; Yoshida, Tadayoshi; Tsujimura, Norio; Nishino, Sho; Okada, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

The Replacement of californium-252 neutron source at Nuclear Fuel Cycle Engineering Laboratories

Hoshi, Katsuya; Yoshida, Tadayoshi; Tsujimura, Norio; Tsuchiko, Yasuhiro*; Suto, Yudai*; Okada, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

Study on the dose estimation method for skin contamination; Count rates of the end-window type GM tube against various contamination sizes and application of VARSKIN

Yoshida, Tadayoshi; Hoshi, Katsuya; Tsujimura, Norio; Okada, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

Study on the evaluation of energy spectra of a deuterium oxide-moderated $$^{241}$$Am-Li neutron field

Hoshi, Katsuya; Nishino, Sho; Yoshida, Tadayoshi; Tsujimura, Norio; Okada, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

The Evaluation of dose equivalent at any depth using a portable beta spectrometer

Hoshi, Katsuya; Yoshida, Tadayoshi; Tsujimura, Norio; Okada, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

Consideration of the applicability of the radiation protection clothes at nuclear facilities

Suga, Takumi; Yamazaki, Takumi; Takada, Chie; Takimoto, Misaki; Okada, Kazuhiko

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)