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Journal Articles

Remote maintenance technologies of equipment and analyzing apparatus in hot cell of Tokai Vitrification Facility, Tokai Reprocessing Plant

Aoya, Juri; Miyata, Katsuhiko*; Terakado, Akihito*; Otsuzumi, Yoji*; Kurosawa, Daiki*; Sunaba, Takanobu*; Oyama, Yuto*; Inada, Satoshi

Nihon Hozen Gakkai Dai-17-Kai Gakujutsu Koenkai Yoshishu, p.507 - 512, 2021/07

The high level radioactive liquid waste is analyzed for the vitrification process control and the vitrified waste quality in the hot cell of Tokai Vitrification Facility, Tokai Reprocessing Plant. There are 8 Master-slave manipulators, 7 lighting equipment, an electronic balance, and an inductively coupled plasma-optical emission spectrometer used for remote operation, securing visibility, total oxide analysis, and elemental analysis in the analytical hot cell. These equipment and analytical apparatus must be secured with the integrity all the time because the vitrification process cannot be proceeded without analysis of the high level radioactive liquid waste. We constructed the self-remote-maintenance technologies of these equipment and analytical apparatus which reduce the risks of radioactive contamination, radiation exposure, and injury of an operator and also were optimized with respect to a labor, time, and cost, based on the operation of approximately 20 years.

Journal Articles

Dose reduction measure in exchange work of valves used for agitation of highly active liquid waste in storage tank

Isozaki, Naohiko; Morimoto, Kenji; Furukawa, Ryuichi; Tsuboi, Masatoshi; Yada, Yuji; Miyoshi, Ryuta; Uchida, Toyomi; Ikezawa, Kazumi*; Kurosawa, Kenji*

Nihon Hozen Gakkai Dai-16-Kai Gakujutsu Koenkai Yoshishu, p.225 - 228, 2019/07

Highly active liquid waste, which is generated by the reprocessing of spent nuclear fuel, is stored in storage tank of Tokai Reprocessing Plant until it is vitrified. The waste solution in the tank is periodically agitated to avoid the precipitation of insoluble residues during the storage. Three way valves and ball valves have been located at the tank for agitation. Radiation dose rate at the valve location is high and operator's radiation exposure become a problem. Therefore, measures to reduce radiation exposure are performed and reported in this presentation.

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:140 Percentile:99.81(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2016

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nemoto, Masashi; Tobita, Keiji; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Nishimura, Tomohiro; Koike, Yuko; et al.

JAEA-Review 2017-028, 177 Pages, 2018/01


Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2016 to March 2017. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Current situations and discussions in Japan in relation to the new occupational equivalent dose limit for the lens of the eye

Yokoyama, Sumi*; Hamada, Nobuyuki*; Hayashida, Toshiyuki*; Tsujimura, Norio; Tatsuzaki, Hideo*; Kurosawa, Tadahiro*; Nabatame, Kuniaki*; Oguchi, Hiroyuki*; Ono, Kazuko*; Kawaura, Chiyo*; et al.

Journal of Radiological Protection, 37(3), p.659 - 683, 2017/09

 Times Cited Count:11 Percentile:84.86(Environmental Sciences)

Since the International Commission on Radiological Protection recommended reducing the occupational equivalent dose limit for the lens of the eye in 2011, there have been extensive discussions in various countries. This paper reviews the current situations in radiation protection of the ocular lens and the discussions on the potential impact of the new lens dose limit in Japan. Topics include historical changes to the lens dose limit, the current situations in occupational lens exposures (e.g., in medical workers, nuclear workers, and Fukushima nuclear power plant workers) and measurements, and the current status of biological studies and epidemiological studies on radiation cataracts. Our focus is on the situations in Japan, but we believe such information sharing will be useful in many other countries.

Journal Articles

Progress report of Japanese simulation research projects using the high-performance computer system Helios in the International Fusion Energy Research Centre

Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03

The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.

Journal Articles

Addendum report of the JHPS expert committee on radiation protection of the lens of the eye, 2; When and how should the dosimetry of beta $$H_{rm p}$$(3) be made?

Akahane, Keiichi*; Iimoto, Takeshi*; Ichiji, Takeshi*; Iwai, Satoshi*; Oguchi, Hiroyuki*; Ono, Kazuko*; Kawaura, Chiyo*; Kurosawa, Tadahiro*; Tatsuzaki, Hideo*; Tsujimura, Norio; et al.

Hoken Butsuri, 50(4), p.257 - 261, 2015/12

In a mixed field of photon and beta radiations, the same dose assigned to skin is normally assigned to the dose to the lens of the eye as a conservative estimate of H$$_{p}$$(3). In exceptional cases that a very high beta dose might be imparted of the same order with the dose limit, however, the conservatively biased dose must be too limiting, and thereby an accurate estimate of beta $$H_{rm p}$$(3) is desirable. This article presents a practical proposal of when and how the dosimetry of beta $$H_{rm p}$$(3) should be made.

Journal Articles

Increase in the beam intensity of the linac-based slow positron beam and its application at the Slow Positron Facility, KEK

Wada, Ken*; Hyodo, Toshio*; Yagishita, Akira*; Ikeda, Mitsuo*; Osawa, Satoshi*; Shidara, Tetsuo*; Michishio, Koji*; Tachibana, Takayuki*; Nagashima, Yasuyuki*; Fukaya, Yuki; et al.

European Physical Journal D, 66(2), p.37 - 40, 2012/02

 Times Cited Count:34 Percentile:86.14(Optics)

no abstracts in English

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:8 Percentile:52.71(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

Journal Articles

A Crossed photon-atom beam method for absolute measurement of total photoionization cross sections on isolated metal atoms; Measurements on Ba and Eu atoms

Obara, Satoshi*; Kobayashi, Ryoei*; Yagi, Shuichi*; Toyama, Yuko*; Kutluk, G.*; Osawa, Tetsutaro*; Ogura, Koichi; Shibata, Takemasa; Azuma, Yoshiro*; Nagata, Tetsuo*

Nuclear Instruments and Methods in Physics Research B, 269(3), p.263 - 271, 2011/02

 Times Cited Count:0 Percentile:0.01(Instruments & Instrumentation)

A crossed photon-atom beam apparatus has been constructed for absolute measurement of total photoionization cross sections of isolated and neutral metallic atoms. Using this apparatus, measurements on Ba and Eu atoms have been made at their 4d giant resonance regions 110-140 eV and 140-180 eV, respectively. The target atom density was determined using the deposition rate on a quartz crystal sensor and the average velocity of the atoms obtained by a time-of-flight method combined with a pulsed electron gun. The number of photons was determined with use of a double ion chamber. The comparison of the measured cross-section values with previous experimental and theoretical results is reasonable, indicating that the crossed photon-atom beam method is fairly promising technique.

Journal Articles

JENDL-4.0; A New library for nuclear science and engineering

Shibata, Keiichi; Iwamoto, Osamu; Nakagawa, Tsuneo*; Iwamoto, Nobuyuki; Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Furutaka, Kazuyoshi; Otsuka, Naohiko*; Osawa, Takaaki*; et al.

Journal of Nuclear Science and Technology, 48(1), p.1 - 30, 2011/01

 Times Cited Count:1249 Percentile:100(Nuclear Science & Technology)

The fourth version of Japanese Evaluated Nuclear Data Library has been produced. In the new library, much emphasis is placed on the improvements of fission product and minor actinoid data. Two nuclear model codes were developed to evaluate the cross sections of fission products and minor actinoids. Coupled-channel optical model parameters, which can be applied to wide mass and energy regions, were obtained for nuclear model calculations. Thermal cross sections of actinoids were determined by considering recent experimental data or by the systematics of neighboring nuclei. A simultaneous evaluation was performed for the fission cross sections of important uranium and plutonium isotopes above 10 keV. The data on FP were re-evaluated, and new evaluations were performed for 30 nuclides. The data on light elements and structural materials were partly re-evaluated. The new library was released as JENDL-4.0 in May 2010.

Journal Articles

Trapping of multiple hydrogen atoms in a tungsten monovacancy from first principles

Osawa, Kazuhito*; Goto, Junya*; Yamakami, Masahiro*; Yamaguchi, Masatake; Yagi, Masatoshi*

Physical Review B, 82(18), p.184117_1 - 184117_6, 2010/11

 Times Cited Count:92 Percentile:94.29(Materials Science, Multidisciplinary)

The configuration of multiple hydrogen atoms trapped in a tungsten monovacancy is investigated using first-principles calculations. Unlike previous computational studies, which have reported that hydrogen in BCC metal monovacancies occupies octahedral interstitial sites, it is found that the stable sites shift towards tetrahedral interstitial sites as the number of hydrogen atoms increases. As a result, a maximum of twelve hydrogen atoms can become trapped in a tungsten monovacancy.

Journal Articles

C-axis critical current of a PrFeAsO$$_{0.7}$$ single crystal

Kashiwaya, Hiromi*; Shirai, Kazumi*; Matsumoto, Tetsuro*; Shibata, Hajime*; Kambara, Hiroshi*; Ishikado, Motoyuki; Eisaki, Hiroshi*; Iyo, Akira*; Shamoto, Shinichi; Kurosawa, Itaru*; et al.

Applied Physics Letters, 96(20), p.202504_1 - 202504_3, 2010/05

 Times Cited Count:27 Percentile:73.57(Physics, Applied)

The ${it c}$-axis transport properties of a high-pressure synthesized PrFeAsO$$_{0.7}$$ single crystal are studied using s-shaped junctions. Resistivity anisotropy of about 120 detected at 50 K shows the presence of strong anisotropy in the electronic states. The obtained critical current density for the ${it c}$-axis of 2.9 $$times$$ 10$$^{5}$$ A/cm$$^{2}$$ is two orders of magnitude larger than that in Bi$$_{2}$$Sr$$_{1.6}$$La$$_{0.4}$$CuO$$_{6+delta}$$. The appearance of a hysteresis in the current-voltage curve below ${it T}$ $$_{c}$$ is the manifestation of the intrinsic Josephson effect similar to that in cuprate superconductors. The suppression of the critical current-normal resistance (${it I}$ $$_{c}$$ ${it R}$ $$_{n}$$) product is explained by an inspecular transport in ${it s}$ $$_{pm}$$ -wave pair potential.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

JAEA Reports

Study on the method of fault zone survey by use of in-situ hydrogen gas measurement

Kurosawa, Hideki; Ishimaru, Tsuneari; Shimada, Koji; Niwa, Masakazu; Kosaka, Hideki*; Saito, Satoshi*; Ninomiya, Atsushi

JAEA-Research 2009-043, 144 Pages, 2010/01


Research on the influence of fault activity on deep geological environments contributes to the reliability of geological disposal systems for HLW. In this study, preliminary test shows that measured value within 1 hour after measurement start is supposed to include hydrogen gas generated by rock fracturing during the drilling of sampling holes and that stored in surrounding disturbed rocks, though the monitoring from a hand-drilled hole is effective for a rapid measurement. We investigated the concentration of hydrogen gas emitted from the Yamasaki fault zone, in southeast Japan. In our survey, the points where high concentrations of hydrogen gas emission was detected were unevenly distributed along the active fault, and in the southeast portion of the study area where small earthquakes frequently occurred.

Journal Articles

JENDL actinoid file 2008

Iwamoto, Osamu; Nakagawa, Tsuneo; Otsuka, Naohiko*; Chiba, Satoshi; Okumura, Keisuke; Chiba, Go; Osawa, Takaaki*; Furutaka, Kazuyoshi

Journal of Nuclear Science and Technology, 46(5), p.510 - 528, 2009/05

JENDL Actinoid File 2008 (JENDL/AC-2008) was released in March 2008. It includes nuclear data for neutron-induced reactions for 79 nuclides from Ac ($$Z=89$$) to Fm ($$Z=100$$). The neutron energy range is $$10^{-5}$$ eV to 20 MeV. Almost all data for 61 actinoids in JENDL-3.3 were revised. New evaluations were performed for 17 nuclides which have half lives longer than 1 day. New comprehensive theoretical model code CCONE was widely used for the evaluation of cross sections and neutron emission spectra. Thermal cross sections for many nuclides were revised based on experimental data. Resonance parameters were readjusted to reproduce them. Simultaneous evaluations of fission cross sections were performed for six important nuclei. The least-squares fitting code GMA was used for evaluation of fission cross sections for minor actinoid. In this paper, we present the evaluation methods and results of the JENDL/AC-2008.

Journal Articles

Progress in R&D efforts on the energy recovery linac in Japan

Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06

Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.

JAEA Reports

Development of image-analysis method of plutonium samples by imaging plate; Measurement of plutonium samples in mixed oxide fuel fabrication facility

Takasaki, Koji; Sagawa, Naoki; Kurosawa, Shigeyuki*; Shioya, Satoshi; Suzuki, Kazunori; Horikoshi, Yoshinori; Mizuniwa, Harumi

JAEA-Technology 2008-028, 73 Pages, 2008/03


Recently, an imaging plate (IP) was developed. Pu analysis by an IP was studied in the JAEA Cooperative Research Scheme on the Nuclear Fuel Cycle, and the availability about detection of Pu and discrimination with radon progenies was shown. In order to apply these results to the radiation control, this research aims at evaluation of radioactivity, discrimination with radon progenies, and evaluation of AMAD by an IP. In the conventional autoradiography (ARG) by a ZnS and Polaroid film, Contamination of Pu can only be grasped by viewing. Since the digital data of the radiation and location is obtained by an IP, Pu can be detected quantitatively and radioactivity can be evaluated. As a result of this research, the image of alpha emitter on an IP is the same as that of the conventional ARG, and can be applied also to the ARG of beta and $$gamma$$ emitter. In measurement of Pu, the function of Image J (image-analysis software) was very available. Pu radioactivity was evaluated by an IP.

Journal Articles

Origin of the monoclinic-to-monoclinic phase transition and evidence for the centrosymmetric crystal structure of BiMnO$$_3$$

Belik, A. A.*; Iikubo, Satoshi; Yokosawa, Tadahiro*; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Azuma, Masaki*; Takano, Mikio*; Kimoto, Koji*; Matsui, Yoshio*; et al.

Journal of the American Chemical Society, 129(4), p.971 - 977, 2007/01

 Times Cited Count:167 Percentile:95.31(Chemistry, Multidisciplinary)

Structural properties of polycrystalline single-phased BiMnO$$_3$$ samples prepared at 6 GPa and 1383 K have been studied by selected area electron diffraction (SAED), convergent beam electron diffraction (CBED), and the Rietveld method using neutron diffraction data measured at 300 and 550 K. The SAED and CBED data showed that BiMnO$$_3$$ crystallizes in the centrosymmetric space group C2/c at 300 K. The analysis of Mn-O bond lengths suggested that the orbital order present in BiMnO$$_3$$ at 300 K melts above T= 474 K. The phase transition at 474 K is of the first order and accompanied by a jump of magnetization and small changes of the effective magnetic moment and Weiss temperature.

Journal Articles

Design of an injector for the ERL test facility

Hajima, Ryoichi; Nagai, Ryoji; Iijima, Hokuto; Nishitani, Tomohiro; Nishimori, Nobuyuki; Osawa, Satoshi*; Sakanaka, Shogo*; Miyajima, Tsukasa*

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.753 - 755, 2006/00

no abstracts in English

53 (Records 1-20 displayed on this page)