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Journal Articles

Calculating off-axis efficiency of coaxial HPGe detectors by Monte Carlo simulation

Omer, M.; Shizuma, Toshiyuki*; Hajima, Ryoichi*; Koizumi, Mitsuo

Radiation Physics and Chemistry, 198, p.110241_1 - 110241_7, 2022/09

JAEA Reports

Development of radiation hardened diamond image sensing devices (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; National Institute of Advanced Industrial Science and Technology*

JAEA-Review 2021-026, 47 Pages, 2021/11

JAEA-Review-2021-026.pdf:2.16MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Development of radiation hardened diamond image sensing devices" conducted in FY2020. The research objective of this project is to develop image sensing devices which work under the high radiation condition. The devices will be realized using radiation hardened diamond semiconductor devices as charge transfer devices and photodetectors. The research project has mainly two targets such as to confirm charge coupled devices operation on diamond unipolar devices and to characterize photo conductivity of diamond detectors.

JAEA Reports

Development of radiation hard diamond image sensing devices (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; National Institute of Advanced Industrial Science and Technology*

JAEA-Review 2020-027, 27 Pages, 2021/01

JAEA-Review-2020-027.pdf:2.98MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Development of radiation hard diamond image sensing devices". The research objective of this project is to develop image sensing devices which work under the high radiation condition. The devices will be realized using radiation hard diamond semiconductor devices as charge transfer devices and photodetectors. The research project has mainly two targets such as to confirm charge coupled devices operation on diamond unipolar devices and to characterize photo conductivity of diamond detectors.

Journal Articles

A Study of directional gamma-ray detector without shield by Monte Carlo simulation

Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki; Torii, Tatsuo

Proceedings of International Youth Nuclear Congress 2020 (IYNC 2020) (Internet), 4 Pages, 2020/05

Journal Articles

Repeatability and reproducibility of measurements of low dissolved radiocesium concentrations in freshwater using different pre-concentration methods

Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11

 Times Cited Count:2 Percentile:32.52(Chemistry, Analytical)

We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the $$^{137}$$Cs results were within $$pm$$2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.

Journal Articles

Reliability estimation of neutron resonance thermometry using tantalum and tungsten

Kai, Tetsuya; Hiroi, Kosuke; Su, Y.; Shinohara, Takenao; Parker, J. D.*; Matsumoto, Yoshihiro*; Hayashida, Hirotoshi*; Segawa, Mariko; Nakatani, Takeshi; Oikawa, Kenichi; et al.

Physics Procedia, 88, p.306 - 313, 2017/06

 Times Cited Count:3 Percentile:84.28

Journal Articles

Measurements and evaluations of air dose rates around Fukushima, 5; Characteristics of air dose rate distribution in the environment around the Fukushima Nuclear Power Plant site

Mikami, Satoshi; Matsuda, Norihiro; Ando, Masaki; Kinase, Sakae; Kitano, Mitsuaki; Kawase, Keiichi; Matsumoto, Shinichiro; Yamamoto, Hideaki; Saito, Kimiaki

Radioisotopes, 64(9), p.589 - 607, 2015/09

This article presents the features of regional distributions and temporal changes in air dose rate and radionuclide deposition densities in Fukushima on the basis of analyses on large-scale environmental monitoring results using diverse methods. The continuity of decontamination effects is discussed according to repeated monitoring data after the decontamination model project. Further, some examples are shown on the projection of air dose rates together with the ecological half lives for different land uses.

Journal Articles

Measurements and evaluations of air dose rates around Fukushima, 4; Practical aspects of air dose rate measurements in the environment

Tsuda, Shuichi; Yoshida, Tadayoshi; Ando, Masaki; Matsuda, Norihiro; Mikami, Satoshi; Tanigaki, Minoru*; Okumura, Ryo*; Takamiya, Koichi*; Sato, Nobuhiro*; Seki, Akiyuki; et al.

Radioisotopes, 64(4), p.275 - 289, 2015/04

This article provides practically useful information on air dose rate measurements in the environments. The basic requirements for the accurate measurements are described giving actual data. The characteristics and some measured results are shown for reliable methods which are widely used in the environmental radiation measurements. Further, information is given on internet sites where air dose rates and related data obtained by official organizations can be browsed.

Journal Articles

New approach to measure double-differential charged-particle emission cross sections of several materials for a fusion reactor

Kondo, Keitaro; Takagi, Satoshi*; Murata, Isao*; Miyamaru, Hiroyuki*; Takahashi, Akito*; Kubota, Naoyoshi; Ochiai, Kentaro; Nishitani, Takeo

Fusion Engineering and Design, 81(8-14), p.1527 - 1533, 2006/02

 Times Cited Count:12 Percentile:64.95(Nuclear Science & Technology)

In a fusion reactor development, double-differential charged-particle emission cross sections(DDXc) are necessary to estimate nuclear heating and material damages of candidate materials irradiated with neutrons. Especially in light nuclei such as Be, Li, and C, nuclear reactions are complicated and difficult to estimate energy spectra of emitted particles based only on theoretical calculations Therefore development of a new technique for precise measurements of DDXc is quite important. Recently we successfully developed a new spectrometer for measurement of DDXc using a pencil-beam DT neutron source of FNS in JAERI. In the present study we carried out measurements of DDXc of $$^{9}$$Be, $$^{12}$$C, $$^{19}$$F, and $$^{27}$$Al using the spectrometer. The present technique was valid from the result of measurement for the $$^{27}$$Al(n,x$$alpha$$) reactions. Slight differences appeared between measured data and evaluation or previous experimental values for $$^{9}$$Be(n,x$$alpha$$) reactions at backward scattering angle and in lower energy region.

Journal Articles

CsI(Tl)/Plastic phoswich detector enhanced in low-energy $$gamma$$-ray detection

Yamasoto, Kotaro; Tsutsumi, Masahiro; Oishi, Tetsuya*; Yoshizawa, Michio; Yoshida, Makoto

Nuclear Instruments and Methods in Physics Research A, 550(3), p.609 - 615, 2005/09

 Times Cited Count:3 Percentile:30.94(Instruments & Instrumentation)

A phoswich detector composed of a thin plate CsI(Tl) scintillator and a plastic scintillator (BC-400) has been designed and evaluated to improve the sensitivity in the low-energy region of large-area plastic scintillation detector. Applicability of the CsI(Tl)/Plastic phoswich detector was examined on radioactivity measurement of massive and large-area materials. The rise-time discrimination technique was applied in order to further improve the minimum detectable activity in the low-energy region. On the basis of the estimation of minimum detectable activity, it was made clear that the energy range of large-area plastic scintillation detector can be expanded down to a few tens of keV by adding a thin plate CsI(Tl) scintillator.

Journal Articles

Centralized radioactivity measurement system for radiation control in Tokai research establishment of JAERI

Kawasaki, Katsuya

Hoken Butsuri, 40(1), p.56 - 60, 2005/03

The centralized radioactivity measurement system has been used to carry out intensively measurements of a large number and variety of samples that are necessary for the control of radioactivity in the facilities of the JAERI Tokai Establishment and its environment. The operation of the system started in 1981, and presently the system processes more than 20,000 samples a year. However, the computers of the system have aged so much that the manufacturer's support and stable operation are no longer sure. Therefore, we renewed and restructured the computer system in 2003. A client-server system was adopted in the new system. The information of samples can be registered through the intranet. The clients can also confirm the progress of processing of their samples and browse the analytical results from their own computers. The renewed system can provide some convenience functions to the clients. This report is introduced about the centralized radioactivity measurement system.

JAEA Reports

Renewal of centralized radioactivity measurement system for radiation control

Kawasaki, Katsuya; Mochizuki, Kaoru*; Suzuki, Takehiko; Kinouchi, Nobuyuki

JAERI-Tech 2004-070, 50 Pages, 2004/12

JAERI-Tech-2004-070.pdf:18.19MB

The centralized radioactivity measurement system has been used to carry out intensively measurements of a large number and variety of samples that are necessary for the control of radioactivity in the facilities of the JAERI Tokai Establishment and its environment. The operation of the system started in 1981, and presently the system processes more than 20,000 samples a year. However, the computers of the system have aged so much that the manufacturer's support and stable operation are no longer sure. Therefore, we renewed and restructured the computer system in 2003. A client-server system was adopted in the new system. The information of samples can be registered through the intranet. The clients can also confirm the progress of processing of their samples and browse the analytical results from their own computers. The renewed system can provide some convenience functions to the clients.

Journal Articles

Determination of detection efficiency curves of HPGe detectors on radioactivity measurement of volume samples

Saegusa, Jun; Kawasaki, Katsuya; Mihara, Akira; Ito, Mitsuo; Yoshida, Makoto

Applied Radiation and Isotopes, 61(6), p.1383 - 1390, 2004/12

 Times Cited Count:27 Percentile:84.9(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Novel instrument system for discriminating secondary particles in high-spatial-resolution neutron detection

Yamagishi, Hideshi; Nakamura, Tatsuya; Soyama, Kazuhiko; Masaoka, Sei; Aizawa, Kazuya

Review of Scientific Instruments, 75(7), p.2340 - 2345, 2004/07

 Times Cited Count:9 Percentile:47.07(Instruments & Instrumentation)

A new instrument system with the capability of secondary-particle discrimination (InSPaD) was studied for the development of two-dimensional neutron detectors (2D-ND) filled with helium-3 gas and with high spatial resolution. The InSPaD can discriminate between the tracks of a proton and a triton created in the nuclear reaction $$^{3}$$He(${it n}$,${it p}$)${it T}$ by simply setting the level of discriminators appropriately in each signal channel, and the system exhibits a high spatial resolution, high counting rate, low background, and stability. The simulations of the 2D-ND equipped with the InSPaD revealed spatial resolutions of 0.46 mm in full width at half maximum for a 10% mixture of C$$_{2}$$H$$_{6}$$ with helium-3 at 0.3 MPa. The results of neutron-detection experiments using a microstrip gas chamber, including the range of the secondary particles and the pulse-height distribution, agreed well with the simulated results, indicating the feasibility of the InSPaD.

JAEA Reports

The Recovery from water leakage accident in JMTR

Ito, Haruhiko; Homma, Kenzo; Itabashi, Yukio; Tabata, Toshio; Akashi, Kazutomo; Inaba, Yukio; Kumahara, Hajime; Takahashi, Kunihiro; Kitajima, Toshio; Yokouchi, Iichiro

JAERI-Review 2003-024, 76 Pages, 2003/10

JAERI-Review-2003-024.pdf:8.35MB

no abstracts in English

JAEA Reports

Secondary $$gamma$$-ray measurements on the D-T neutron skyshine experiments

Tanaka, Ryohei*; Ochiai, Kentaro; Nakao, Makoto*; Yamauchi, Michinori*; Hori, Junichi; Wada, Masayuki*; Sato, Satoshi; Nishitani, Takeo

JAERI-Tech 2003-063, 62 Pages, 2003/07

JAERI-Tech-2003-063.pdf:3.41MB

no abstracts in English

Journal Articles

Development of micro-strip gas chamber with individual readout

Nakamura, Tatsuya; Masaoka, Sei; Yamagishi, Hideshi; Soyama, Kazuhiko; Aizawa, Kazuya

Proceedings of ICANS-XVI, Volume 1, p.441 - 446, 2003/07

Development of a Micro-Strip Gas Chamber(MSGC) in JAERI is presented. The performances we aim at are counting rate $$>$$10$$^{6}$$${it cps/mm}$$$^{2}$$, position resolution $$<$$1${it mm}$, detection efficiency $$>$$60% at thermal neutron and good n/gamma discrimination. Our two-dimensional gas detector consists of a micro strip plate printed on a polyimide substrate and a high pressure gas chamber which has all the signal lines are directly taken out (256ch individual readout) and withstands the pressure of 10bar $$^{3}$$${it He}$. The individual signal readout opens the way to realize high counting rate and high position resolution at the same time. We carried out range measurements of secondary particles to confirm the range measuring power of the MSGC with that read out method. The measured ranges in the gas of 3bar helium mixed with $$10%$$ ethane is 3mm, 9.5mm for triton and proton, respectively. Those values are well agreed with theoretical estimation and we could show the feasibility of the precise measurement of the ranges by the MSGC.

JAEA Reports

Research and development for the high-temperature helium-leak detection system, 2; Development of temperature sensors using optical fibre for the HTTR (Joint research)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*

JAERI-Tech 2003-041, 106 Pages, 2003/03

JAERI-Tech-2003-041.pdf:6.58MB

In the second stage of the research and development for a high-temperature helium-leak detection system, the temperature sensor using optical fibres was studied. The sensor detects the helium leakage by the temperature inclease surrounded opitical fibre with or without heat insulator. Moreover, the applicability of high temperature equipments as the HTTR system was studied. With the sensor we detected 5.0-20.0 cm$$^{3}$$/s helium leakages within 60 minutes. Also it was possible to detect earlier when the leakage level is at 20.0 cm$$^{3}$$/s.

JAEA Reports

Report on the water leakage from instrumentation pipe in JMTR

JMTR Pressure Measurement Pipe Investigation Committee

JAERI-Review 2003-014, 117 Pages, 2003/03

JAERI-Review-2003-014.pdf:27.62MB

On December 10、2002, the leak was found at the pressure measurement pipe attached to the exit pipe of No.1 filing pump of the refining system of a primary cooling system at JMTR in Oarai Research establishment JAERI. Investigation Committee for Water Leakage from Instrumentation Pipe in JMTR was established and organized by specialists from inside and outside JAERI on December 16 and its meeting was held in public 3 times by 6th January, 2003. They investigated the cause and countermeasures of cracks, and also investigated enhancement of safety management. This is the report on the cause and countermeasures of cracks and enhancement of safety management.

JAEA Reports

Research and development of a high-temperature helium-leak detection system, 1; Survey on leakage events and current leak detection technology (Joint research)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*

JAERI-Review 2002-041, 86 Pages, 2003/03

JAERI-Review-2002-041.pdf:3.21MB

In High Temperature Gas-cooled Reactors (HTGR), the detection of leakage of helium at an early stage is very important for the safety and stability of operations. Since helium is a colourless gas, it is generally difficult to identify the location and the amount of leakage when very little leakage has occurred. The purpose of this R&D is to develop a helium-leak detection system for the high temperature environment appropriate to the HTTR. This system can shorten the time of detection to several hours from about one week in the current detection time. In addition, it can also identify easily the leak location using the optical fibre network. As the first step in the development, this paper describes the result of surveying leakage events at nuclear facilities inside and outside Japan and current gas leakage detection technology to adapt optical fibre detection technology to HTGRs.

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