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Journal Articles

From recent RPT review articles; Medical application of particle and heavy ion transport code system PHITS

Furuta, Takuya

Igaku Butsuri, 41(4), P. 194, 2021/12

Number of medical uses of Particle and Heavy Ion Transport code System (PHITS) has been increased due to the recent high demands of medical use of radiations. The summary of such research works was described in the review article on medical application of Particle and Heavy Ion Transport code System PHITS published in Radiological Physics and Technology in 2021. There was a request from the editorial board of Japan Society of Medical Physics (JSMP) for writing an introductory article of this article in their internal journal. The research works on medical applications described in the review article, useful functions for medical application in PHITS, and newly opened user forum of PHITS have been introduced.

JAEA Reports

Report of the design examination and the installation work for the radiation shield at the beam injection area in the 3 GeV synchrotron

Nakanoya, Takamitsu; Kamiya, Junichiro; Yoshimoto, Masahiro; Takayanagi, Tomohiro; Tani, Norio; Kotoku, Hirofumi*; Horino, Koki*; Yanagibashi, Toru*; Takeda, Osamu*; Yamamoto, Kazami

JAEA-Technology 2021-019, 105 Pages, 2021/11

JAEA-Technology-2021-019.pdf:10.25MB

Since a user operation startup, the 3 GeV synchrotron accelerator (Rapid-Cycling Synchrotron: RCS) gradually reinforced the beam power. As a result, the surface dose rate of the apparatus located at the beam injection area of the RCS, such as the magnet, vacuum chambers, beam monitors, etc., increases year by year. The beam injection area has many apparatuses which required manual maintenance, so reducing worker's dose is a serious issue. To solve this problem, we have organized a task force for the installation of the shield. The task force has aimed to optimize the structure of the radiation shield, construct the installation procedure with due consideration of the worker's dose suppression. As the examination result of the shield design, we have decided to adopt removal shielding that could be installed quickly and easily when needed. We carried out shield installation work during the 2020 summer maintenance period. The renewal work required to install the shielding has been carried out in a under high-dose environment. For this reason, reducing the dose of workers was an important issue. So, we carefully prepared the work plan and work procedure in advance. During the work period, we implemented various dose reduction measures and managed individual dose carefully. As a result, the dose of all workers could be kept below the predetermined management value. We had installed removal shielding at the beam injection area in the 2020 summer maintenance period. We confirmed that this shield can contribute to the reduction of the dose during work near the beam injection area. It was a large-scale work to occupy the beam injection area during almost of the summer maintenance period. However, it is considered very meaningful for dose suppression in future maintenance works.

Journal Articles

Radiation shielding installation for beam injection section of 3GeV synchrotron

Nakanoya, Takamitsu; Kamiya, Junichiro; Yoshimoto, Masahiro; Takayanagi, Tomohiro; Tani, Norio; Kotoku, Hirofumi*; Horino, Koki*; Yanagibashi, Toru*; Takeda, Osamu*; Yamamoto, Kazami

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.238 - 242, 2021/10

Since a user operation startup, the 3GeV synchrotron accelerator (Rapid-Cycling Synchrotron: RCS) gradually reinforced the beam power. As a result, the surface dose rate of the apparatus located at the beam injection area of the RCS increases year by year. The beam injection area has many apparatuses which required manual maintenance, so reducing worker's dose is a serious issue. To solve this problem, we have decided to adopt removal shielding that could be installed quickly and easily when needed. We carried out shield installation work during the 2020 summer maintenance period. The installation work of the shield has been carried out in a under high-dose environment. For this reason, reducing the dose of workers was an important issue. So, we carefully prepared the work plan and work procedure in advance. During the work period, we implemented various dose reduction measures and managed individual dose carefully. As a result, the dose of all workers could be kept below the predetermined management value. We had installed removal shielding at the beam injection area in the 2020 summer maintenance period. We confirmed that this shield can contribute to the reduction of the dose during work near the beam injection area.

Journal Articles

Medical application of Particle and Heavy Ion Transport code System PHITS

Furuta, Takuya; Sato, Tatsuhiko

Radiological Physics and Technology, 14(3), p.215 - 225, 2021/09

Number of the PHITS users has steadily increased since 2010 from when it is officially counted. Among them, increase of new users in medical physics is outstanding. Many research works in medical physics using PHITS have been published and the applications are widely spread in different fields such as applications to different types of radiotherapy, shielding calculations of medical facilities, application to radiation biology, and research and development of medical tools. In this article, we will introduce useful functions for medical application in PHITS by referring to examples of various medical applications.

JAEA Reports

Study on the radioactivity evaluation method of biological shielding concrete of JPDR for near surface disposal

Kochiyama, Mami; Okada, Shota; Sakai, Akihiro

JAEA-Technology 2021-010, 61 Pages, 2021/07

JAEA-Technology-2021-010.pdf:3.56MB
JAEA-Technology-2021-010(errata).pdf:0.75MB

It is necessary to evaluate the radioactivity inventory in wastes in order to dispose of radioactive wastes generated from dismantling nuclear reactor in the shallow ground. In this report, we examined radioactivity evaluation method for near surface disposal about biological shield concrete near the core generated from the dismantling of JPDR. We calculated radioactive concentration of the target biological concrete using the DORT code and the ORIGEN-S code, and we estimated radioactivity concentration Di (Bq/t). For DORT calculation, the cross-section library created from the MATXSLIB-J40 file from JENDL-4.0 was used, and for ORIGEN-S, the attached library of SCALE6.0 was used. As a result of comparing the calculation results of the radioactivity concentration with the past measured values in the radial direction and the vertical direction, we found that the trends were generally the same. We calculated radioactive concentration of the target biological concrete Di (Bq/t), and we compared with the estimated Ci (Bq/t) equivalent to the dose criteria of trench disposal calculated for 140 nuclides. As a result we inferred that the except for about 2% of target waste could be disposed of in the trench disposal facility. We also preselected important nuclides for trench disposal based on the ratios (Di/Ci) for each nuclide, H-3, C-14, Cl-36, Ca-41, Co-60, Sr-90, Eu-152 and Cs-137 were selected as important nuclides.

JAEA Reports

Research and development of transparent materials for radiation shield using nanoparticles (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Kyushu University*

JAEA-Review 2020-036, 176 Pages, 2021/01

JAEA-Review-2020-036.pdf:9.55MB

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 FY2018, this report summarizes the research results of the "Research and Development of Transparent Materials for Radiation Shield Using Nanoparticles" conducted in FY2019. The present study aims to reduce radiation exposure of workers in debris retrieval/analysis and reduce deterioration of optical and electronic systems in remote cameras. For these purposes, we develop transparent radiation shield by making the shield materials into nanoparticles, and dispersing/solidifying them in epoxy resin. By making boride or heavy metal compounds into nanoparticles, we will also develop a radiation shield that shields both neutrons and gamma-rays, and also suppresses secondary gamma-rays produced from neutrons.

Journal Articles

Total cross section model with uncertainty evaluated by KALMAN

Hashimoto, Shintaro; Sato, Tatsuhiko

EPJ Web of Conferences, 239, p.03015_1 - 03015_4, 2020/09

 Times Cited Count:0 Percentile:0.19

Particle transport simulation codes based on the Monte Carlo technique have been successfully applied to shielding calculations in accelerator facilities. Estimation of not only statistical uncertainties, which depend on the number of trials, but also systemic uncertainties, which are caused by uncertainty of total cross section models, is required to confirm the reliability of the simulation results. We evaluated unclear quantities of internal parameters included in the total cross section model by the KALMAN code, which is based on the least squares technique, comparing with experimental data of the total cross section. The uncertainties in the total cross sections obtained by the new model are comparable to the experimental errors. In the present study, the systematic uncertainty included in the simulation results can be estimated by performing the transport calculations with variation of the internal parameters within their unclear quantities.

JAEA Reports

Research and development of transparent materials for radiation shield using nanoparticles (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

Collaborative Laboratories for Advanced Decommissioning Science; Kyushu University*

JAEA-Review 2019-039, 104 Pages, 2020/03

JAEA-Review-2019-039.pdf:5.57MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. 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 FY2018, this report summarizes the research results of the "Research and Development of Transparent Materials for Radiation Shield using Nanoparticles". The present study aims to reduce radiation exposure of workers in debris retrieval/analysis and reduce deterioration of optical and electronic systems in remote cameras. For these purposes, we develop transparent radiation shield by making the shield materials into nanoparticles, and dispersing/solidifying them in epoxy resin. By making B$$_{4}$$C and W into nanoparticles, we will also develop a radiation shield that shields both neutrons and gamma-rays, and also suppresses secondary gamma-rays produced from neutrons.

Journal Articles

Estimation method of systematic uncertainties in Monte Carlo particle transport simulation based on analysis of variance

Hashimoto, Shintaro; Sato, Tatsuhiko

Journal of Nuclear Science and Technology, 56(4), p.345 - 354, 2019/04

 Times Cited Count:1 Percentile:17.09(Nuclear Science & Technology)

Particle transport simulations based on the Monte Carlo method have been applied to shielding calculations. Estimation of not only statistical uncertainty related to the number of trials but also systematic one induced by unclear physical quantities is required to confirm the reliability of calculated results. In this study, we applied a method based on analysis of variance to shielding calculations. We proposed random- and three-condition methods. The first one determines randomly the value of the unclear quantity, while the second one uses only three values: the default value, upper and lower limits. The systematic uncertainty can be estimated adequately by the random-condition method, though it needs the large computational cost. The three-condition method can provide almost the same estimate as the random-condition method when the effect of the variation is monotonic. We found criterion to confirm convergence of the systematic uncertainty as the number of trials increases.

Journal Articles

Shielding

Maekawa, Fujio

Hamon, 28(4), p.208 - 211, 2018/11

Adequate shielding of neutrons and associated $$gamma$$-rays is of importance from viewpoints of the radiation safety of researchers and good experimental data taking by reducing the background. This article introduces basics of neutron shielding, physics and suitable materials for neutron and $$gamma$$-ray shielding, and an example of conceptual shielding design for the 1-MW spallation neutron source of J-PARC MLF.

Journal Articles

Review of reduction factors by buildings for gamma radiation from radiocaesium deposited on the ground due to fallout

Yoshida-Ouchi, Hiroko*; Matsuda, Norihiro; Saito, Kimiaki

Journal of Environmental Radioactivity, 187, p.32 - 39, 2018/07

 Times Cited Count:10 Percentile:18.19(Environmental Sciences)

Journal Articles

A Proposal of secure non-destructive detection system of nuclear materials in heavily shielded objects and interior investigation system

Seya, Michio; Hajima, Ryoichi*; Kureta, Masatoshi

Proceedings of INMM 58th Annual Meeting (Internet), 10 Pages, 2017/07

Large size freight cargo containers are the most vulnerable items from nuclear security points of view because of their large volume and weight of cargo inside for hiding heavily shielded objects. For strengthening nuclear security, secure detection of NMs in heavily shielded objects, and safe handling (dismantlement) of detected (suspicious) objects, are essential. These require secure detection of NMs, inspection of detailed interior structures of detected objects, rough characterization of NMs (for nuclear bomb or RDD etc.) and confirmation of existence of explosives etc. By using information obtained by these inspections, safe dismantlement of objects is possible. In this paper, we propose a combination of X-ray scanning system with NRF-based NDD system using monochromatic $$gamma$$-ray beam for a secure detection and interior inspections. We also we propose active neutron NDA system using a DT source for interior inspection of NM part.

JAEA Reports

Shielding calculation by PHITS code during replacement works of startup neutron sources for HTTR operation

Shinohara, Masanori; Ishitsuka, Etsuo; Shimazaki, Yosuke; Sawahata, Hiroaki

JAEA-Technology 2016-033, 65 Pages, 2017/01

JAEA-Technology-2016-033.pdf:11.14MB

To reduce the neutron exposure dose for workers during the replacement works of the startup neutron sources of the High Temperature Engineering Test Reactor, calculations of the exposure dose in case of temporary neutron shielding at the bottom of fuels handling machine were carried out by the PHITS code. As a result, it is clear that the dose equivalent rate due to neutron radiation can be reduced to about an order of magnitude by setting a temporary neutron shielding at the bottom of shielding cask for the fuel handling machine. In the actual replacement works, by setting temporary neutron shielding, it was achieved that the cumulative equivalent dose of the workers was reduced to 0.3 man mSv which is less than half of cumulative equivalent dose for the previous replacement works; 0.7 man mSv.

Journal Articles

Development of transportation container for the neutron startup source of High Temperature engineering Test Reactor (HTTR)

Shimazaki, Yosuke; Ono, Masato; Tochio, Daisuke; Takada, Shoji; Sawahata, Hiroaki; Kawamoto, Taiki; Hamamoto, Shimpei; Shinohara, Masanori

Proceedings of International Topical Meeting on Research Reactor Fuel Management and Meeting of the International Group on Reactor Research (RRFM/IGORR 2016) (Internet), p.1034 - 1042, 2016/03

In High Temperature Engineering Test Reactor (HTTR), three neutron holders containing $$^{252}$$Cf with 3.7 GBq for each are loaded in the graphite blocks and inserted into the reactor core as a neutron startup source which is changed at the interval of approximately ten years. These neutron holders containing the neutron sources are transported from the dealer's hot cell to HTTR using the transportation container. The holders loading to the graphite block are carried out in the fuel handling machine maintenance pit of HTTR. There were two technical issues for the safety handling work of the neutron holder. The one is the radiation exposure caused by significant movement of the container due to an earthquake, because the conventional transportation container was so large ($$phi$$1240 mm, h1855 mm) that it can not be fixed on the top floor of maintenance pit by bolts. The other is the falling of the neutron holder caused by the difficult remote handling work, because the neutron holder capsule was also so long ($$phi$$155 mm, h1285 mm) that it can not be pulled into the adequate working space in the maintenance pit. Therefore, a new and low cost transportation container, which can solve the issues, was developed. To avoid the neutron and $$gamma$$ ray exposure, smaller transportation container ($$phi$$820mm, h1150 mm) which can be fixed on the top floor of maintenance pit by bolts was developed. In addition, to avoid the falling of the neutron holder, smaller neutron holder capsule ($$phi$$75 mm, h135 mm) with simple handling mechanism which can be treated easily by manipulator was also developed. As the result of development, the neutron holder handling work was safely accomplished. Moreover, a cost reduction for manufacturing was also achieved by simplifying the mechanism of neutron holder capsule and downsizing.

Journal Articles

Design of "NeutrOn Beam-line for Observation & Research Use (NOBORU)" for JSNS of J-PARC

Maekawa, Fujio; Oikawa, Kenichi; Tamura, Masaya; Harada, Masahide; Ikeda, Yujiro; Watanabe, Noboru

LA-UR-06-3904, Vol.1, p.129 - 138, 2006/06

Total 23 neutron beam-lines will be installed for JSNS in the J-PARC project. One of them is assigned for the Materials and Life Science Facility (MLF), and the MLF will construct a neutron beam-line to demonstrate and monitor neutronic performance of JSNS. The neutron beam-line was accordingly named as "Neutron Beam-line for Obserbation and Research Use (NOBORU)". Major parts of the NOBORU, i.e., beam ducts, shield, a beam stop, slits, a cabin for measurement, a pillar crane, a sample table, etc., have been ordered in March 2004, and installation will be completed in 2007. A T0 chopper, a frame-overlap chopper, detector systems, samples, etc. will be ordered later on. The sample position is at 14 m from the decoupled moderator. Approximate sample room dimensions are 3 $$times$$ 2.5 m in area and 3 m in height. A shield structure was determined by shielding calculations in which detailed 3-D structure was considered. The design of NOBORU will be presented in the session.

Journal Articles

A Preliminaly investigation on the satellite building of MLF; Beamline shielding analysis

Oikawa, Kenichi; Maekawa, Fujio; Tamura, Masaya; Harada, Masahide; Kato, Takashi; Ikeda, Yujiro; Niita, Koji*

LA-UR-06-3904, Vol.2, p.139 - 145, 2006/06

A preliminary investigation on a satellite building for a long-beamline instrument of MLF is now in progress. In order to estimate the total cost of the building, we started the shielding analysis of the beamline using MCNPX and PHITS, where the latest beamline design and the neutron spectrum have been adopted.

Journal Articles

Neutronics design of the low aspect ratio tokamak reactor, VECTOR

Nishitani, Takeo; Yamauchi, Michinori*; Nishio, Satoshi; Wada, Masayuki*

Fusion Engineering and Design, 81(8-14), p.1245 - 1249, 2006/02

 Times Cited Count:13 Percentile:67.77(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Neutronics assessment of advanced shield materials using metal hydride and borohydride for fusion reactors

Hayashi, Takao; Tobita, Kenji; Nishio, Satoshi; Ikeda, Kazuki*; Nakamori, Yuko*; Orimo, Shinichi*; DEMO Plant Design Team

Fusion Engineering and Design, 81(8-14), p.1285 - 1290, 2006/02

 Times Cited Count:20 Percentile:80.39(Nuclear Science & Technology)

Neutron transport calculations were carried out to evaluate the capability of metal hydrides and borohydrides as an advanced shielding material. Some hydrides indicated considerably higher hydrogen content than polyethylene and solid hydrogen. The hydrogen-rich hydrides show superior neutron shielding capability to the conventional materials. From the temperature dependence of dissociation pressure, ZrH$$_{2}$$ and TiH$$_{2}$$ can be used without releasing hydrogen at the temperature of less than 640 $$^{circ}$$C at 1 atm. ZrH$$_{2}$$ and Mg(BH$$_{4}$$)$$_{2}$$ can reduce the thickness of the shield by 30% and 20% compared to a combination of steel and water, respectively. Mixing some hydrides with F82H produces considerable effects in $$gamma$$-ray shielding. The neutron and $$gamma$$-ray shielding capabilities decrease in order of ZrH$$_{2}$$ $$>$$ Mg(BH$$_{4}$$)$$_{2}$$ and F82H $$>$$ TiH$$_{2}$$ and F82H $$>$$ water and F82H.

Journal Articles

Comparison of thermal neutron distributions within shield materials obtained by experiments, SN and Monte Carlo code calculations

Asano, Yoshihiro; Sugita, Takeshi*; Suzaki,Takenori; Hirose, Hideyuki

Radiation Protection Dosimetry, 116(1-4), p.284 - 289, 2005/12

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

no abstracts in English

Journal Articles

Comparison of synchrotron radiation calculations between analytical codes(STAC8,PHOTON) and Monte Carlo codes (FLUKA,EGS4)

Liu, J. C.*; Fasso, A.*; Prinz, A.*; Rokni, S.*; Asano, Yoshihiro

Radiation Protection Dosimetry, 116(1-4), p.658 - 661, 2005/12

 Times Cited Count:6 Percentile:41.76(Environmental Sciences)

no abstracts in English

263 (Records 1-20 displayed on this page)