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Cs released by the Fukushima Daiichi Nuclear Power Plant to the coastal areaSato, Shun; Wakiyama, Yoshifumi*; Takahashi, Fumiaki; Takata, Hyoe*
Science of the Total Environment, 1000, p.180380_1 - 180380_14, 2025/10
We compared the ongoing direct release of Cs from the Fukushima Daiichi Nuclear Power Plant (FDNPP) and riverine inputs of Cs that have contributed to the persistent elevated Cs in coastal waters around the plant since 2012. The direct release of Cs clearly decreased from 17.5 TBq during 2012
2014 to 0.6 TBq during 20192021 because of measures implemented by the FDNPP. The riverine input decreased slightly from 2.2 TBq during 20122014 to 2.0 TBq during 20192021. The ratio of direct release to the total Cs flux into the coastal water around the FDNPP decreased from 89% during 20122014 to 23% during 20192021. This change resulted in part from a lowering of the limit of detection of Cs activities to avoid overestimation of Cs fluxes from the facility, but also from installation of an impermeable seaside wall. The trend of decreasing riverine Cs input might have been due entirely to environmental remediation. Our results indicate that the contribution of riverine input to the coastal waters will continue for a long time. Precise prediction of the long-term distribution of Cs in the marine environment will require consideration of a variety of environmental factors and anthropogenic effects.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：8 Percentile：71.12(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki
Journal of Nuclear Science and Technology, 59(5), p.656 - 664, 2022/05
Times Cited Count：1 Percentile：8.19(Nuclear Science & Technology)It is known that internal doses depend on the physical characteristics of an evaluation subject. Internal dose coefficients provided by the International Commission on Radiological Protection (ICRP) are evaluated using the characteristics of the standard Caucasian. It is important to grasp the variations of doses due to the differences in characteristics between Japanese and Caucasian when the dose coefficients of ICRP are applied to Japanese. This study evaluated dose coefficients using specific absorbed fraction (SAF) data based on the average adult Japanese physique which was developed by modification of the existing Japanese SAF data with additional calculations to make the existing data fit to the current dosimetric methodology of ICRP and compared them to those provided by ICRP. As a result, the discrepancies in dose coefficients were smaller than plus or minus 10% in most intake conditions. However, some intake conditions indicated varieties over 40% due to the differences in organ masses, amount of adipose tissues around the thoracic cavity, and so on. This information is useful in application of ICRP's dose coefficients to population of which physical characteristics are different from those of Caucasian. Further, the Japanese SAF data is published as an appendix of this paper.
Takahashi, Fumiaki; Manabe, Kentaro; Sato, Kaoru
JAEA-Review 2020-068, 114 Pages, 2021/03
JAEA-Review-2020-068.pdf:2.61MB
Radiation safety regulations have been currently established based on the 1990Recommendation by the International Commission on Radiological Protection (ICRP) in Japan. Meanwhile, ICRP released the 2007 Recommendation that replaces the 1990 Recommendation. Thus, the Radiation Council, which is established under the Nuclear Regulation Authority (NRA), has made discussions to incorporate the purpose of the 2007 Recommendation into Japanese regulations for radiation safety. As ICRP also has published effective dose coefficients for internal exposure assessment in accordance with the 2007recommendation, the technical standards are to be revised for the internal exposure assessment method in Japan. Currently, not all of the effective doses have been published to revise concentration limits for internal exposure protections of workers and public. The published effective dose coefficients are applied to radionuclides which are important in radiation protection for internal exposure of a worker. Thus, we review new effective dose coefficients as well as basic dosimetry models and data based upon Occupational Intakes of Radionuclides (OIR) parts 2, 3 and 4 that have been published from 2016 to 2019 by ICRP. In addition, issues are sorted out to provide information for revision of the technical standards for internal exposure assessment based on the 2007 Recommendations in future.
Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki
BIO Web of Conferences (Internet), 14, p.03011_1 - 03011_2, 2019/05
Times Cited Count：2 Percentile：82.95(Public, Environmental & Occupational Health)Dose coefficients, which are committed effective dose per unit intake of radionuclides, are fundamental amounts for dose estimation and protection standards against internal exposures. In this study, we built a calculation function of dose coefficients using the latest dosimetric models and data as a part of development of internal dosimetry code in accordance with 2007 Recommendations of the International Commission of Radiological Protection (ICRP). Quality of the function was assured by comparing the results generated by the function to values recorded in a database of dose coefficients for workers provided by ICRP. In the presentation, we will report the results of quality assurance and the future plans of code development.
Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki
Journal of Nuclear Science and Technology, 56(5), p.385 - 393, 2019/05
Times Cited Count：5 Percentile：37.86(Nuclear Science & Technology)At high energy accelerator facilities, various radionuclides are produced by nuclear reactions of high energy particles with structure and/or ambient air of the facilities. Consequently, the radionuclides are potential sources of internal exposure for works of the facilities. However, the International Commission on Radiological Protection (ICRP) do not provide dose coefficients, which are committed effective doses per intake, for the short-lived radionuclides whose half-lives are shorter than 10 minutes in accordance with the ICRP 2007 Recommendations. Then, we estimated the dose coefficients for inhalation and ingestion of these short-lived radionuclides in accordance with the ICRP 2007 Recommendations. In addition, we compared the dose coefficients with those in accordance with the ICRP 1990 Recommendations. As a result, a decreasing tendency was shown in the dose coefficients for inhalation cases; an increasing tendency was observed in those for ingestion cases. It was found that these changes in dose coefficients were mainly caused by the revision of the dose calculation procedures, alimentary tract models. The result of this study will be useful for planning of radiation protection at the high energy facilities.
Sato, Kaoru; Takahashi, Fumiaki
Hoken Butsuri, 52(4), p.247 - 258, 2017/12
Organ doses for dose assessment in radiation protection are derived from ICRP reference phantoms (Male:RCP-AM, Female:RCP-AF) with standard Caucasian physiques. In adult, Japanese are smaller than Caucasian. To study impact of differences in physiques between Caucasian and Japanese on organ doses, we previously constructed Japanese phantoms (Male:JM-103, Female:JF-103) with average adult Japanese physiques. In addition, adult Japanese physiques have also wide distribution. Thus, we newly modeled DJM (Male) and DJF (Female) with 8 physiques by changing the perimeters of JM-103 and JF-103. Organ doses due to external photon irradiation of DJM and DJF were calculated, and were compared with those of RCP-AM and RCP-AF. In ISO geometry at 0.3 MeV, it was found that doses of breast, colon, lung, stomach, gonad, urinary bladder, esophagus, liver and thyroid in DJM and DJF with physiques, which are applicable to most adult Japanese, agreed with those of RCP-AM and RCP-AF within 10%.
Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki
JAEA-Data/Code 2016-013, 48 Pages, 2016/12
JAEA-Data-Code-2016-013.pdf:1.3MB
JAEA-Data-Code-2016-013-appendix(CD-ROM).zip:0.47MB
In the 2007 Recommendations of the International Commission on Radiological Protection (ICRP), an effective dose is defined as a sum of equivalent doses which are calculated by using male and female reference phantoms based on Caucasian physiological data and averaged over the sexes by tissue weighting factors. Specific absorbed fractions (SAFs), which are essential for internal dosimetry, depend on the body weight and organ masses of phantoms. Then, the dose coefficients, which are committed effective doses per unit intake of radionuclides, developed by ICRP on the basis of the 2007 Recommendations reflect the physical characteristics of Caucasians and are averaged over the sexes. Meanwhile, the physiques of adult Japanese are generally smaller than those of adult Caucasians, and organ masses are also different from each other. Knowledge of the influence of race differences on dose coefficients is important to apply the sex averaged dose coefficients of ICRP to the Japanese system of radiation protection. In this study, SAFs for 25 kinds of mono-energetic electrons and photons ranging from 10 keV to 10 MeV were calculated about the combinations of 67 source regions and 42 target organs using the average adult Japanese female phantom, JF-103, incorporated with a general purpose radiation transport code, MCNPX 2.6.0. The data of this report and the previously published data of JM-103 are applicable to evaluate sex-specific and sex-averaged dose coefficients reflecting the physical characteristics of the average adult Japanese for intakes of all radionuclides not to emit other than photons and electrons.
Hori, Toshihiko; Shinozaki, Shinichi; Chishiro, Etsuji; Sato, Fumiaki; Kawamura, Masato*; Futatsukawa, Kenta*; Fukui, Yuji*; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 8, p.011010_1 - 011010_5, 2015/09
Hori, Toshihiko; Shinozaki, Shinichi; Sato, Fumiaki; Fukui, Yuji*; Futatsukawa, Kenta*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.643 - 646, 2015/09
We are making efforts to decrease the fault rate of the high voltage power supplies for 324 MHz klystron. A new Veto module has been developed to prevent the 25 Hz trigger fan out module from malfunction due to the klystron discharge. As the result of installing the Veto module to the SDTL#16 klystron station, the klystron had never stopped for two months operation although the discharge occurred forty-two times during the operation. It confirmed that the installation of the Veto module is extremely useful to operate the klystron stably.
Futatsukawa, Kenta*; Kobayashi, Tetsuya*; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; Hirano, Koichiro; Fang, Z.*; Fukui, Yuji*; Hori, Toshihiko; Michizono, Shinichiro*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1317 - 1320, 2015/09
In the J-PARC linac, an RF deflector installed in 3-MeV Medium Energy Beam Transport (MEBT1) is used to kick the unnecessary beam and the intermediate-pulse like a comb is created. The kicked beam leads to a scraper downstream the RF deflector and lose all kinetic energy. When the beam current increases to 50 mA of the design value, the heat load of a scraper to irradiate the kicked beam increases and its surface is predicted to be damaged. Therefore, we are preparing the tandem scrapers to reduce the damage. The half of the kicked beam leads to a scraper and the residual is to the other. The chopping operation is achieved by rotating the phase of the RF deflector in the periodic cycles by the LLRF system. We will introduce the phase rotation system and the test results.
Takahashi, Fumiaki; Sato, Kaoru; Endo, Akira; Ono, Koji*; Ban, Nobuhiko*; Hasegawa, Takayuki*; Katsunuma, Yasushi*; Yoshitake, Takayasu*; Kai, Michiaki*
Health Physics, 109(2), p.104 - 112, 2015/08
Times Cited Count：10 Percentile：61.98(Environmental Sciences)A dosimetry system, named WAZA-ARI, is developed to assess accurately radiation doses to persons from Computed Tomography (CT) examination patients in Japan. Organ doses were prepared to application to dose calculations in WAZA-ARI by numerical analyses using average adult Japanese human models with the Particle and Heavy Ion Transport code System (PHITS). Experimental studies clarified the radiation configuration on the table for some multi-detector row CT (MDCT) devices. Then, a source model in PHITS could specifically take into account for emissions of X-ray in each MDCT device based on the experiment results. Numerical analyses with PHITS revealed a concordance of organ doses with human body size. The organ doses by the JM phantoms were compared with data obtained using previously developed systems. In addition, the dose calculation in WAZA-ARI were verified with previously reported results by realistic NUBAS phantoms and radiation dose measurement using a physical Japanese model. The results implied that analyses using the Japanese phantoms and PHITS including source models can appropriately give organ dose data with consideration of the MDCT device and physiques of typical Japanese adults.
Ando, Masaki; Nakahara, Yukio; Tsuda, Shuichi; Yoshida, Tadayoshi; Matsuda, Norihiro; Takahashi, Fumiaki; Mikami, Satoshi; Kinouchi, Nobuyuki; Sato, Tetsuro*; Tanigaki, Minoru*; et al.
Journal of Environmental Radioactivity, 139, p.266 - 280, 2015/01
Times Cited Count：56 Percentile：80.88(Environmental Sciences)A series of car-borne surveys using the KURAMA and KURAMA-II systems was conducted in a wide area in eastern Japan from June 2011 to December 2012 to evaluate the distribution of air dose rates around the Fukushima Dai-ichi Nuclear Power Plant, and to determine the time-dependent trend of decrease in air dose rates. An automated data processing system was established, which enables analyses of large amounts of data obtained with the use of about 100 units of the measurement system in a short time. The initial data for studying the migration status of radioactive cesium was obtained in the first survey, followed by the other car-borne surveys having wider measurement ranges. Comparing the measured air dose rates obtained in each survey, it was found that the decreasing trend of air dose rates measured through car-borne surveys was larger than that expected from the physical decay of radioactive cesium and that measured using NaI (Tl) survey meters around the road.
Sato, Kaoru; Takahashi, Fumiaki; Endo, Akira; Ono, Koji*; Hasegawa, Takayuki*; Katsunuma, Yasushi*; Yoshitake, Takayasu*; Ban, Nobuhiko*; Kai, Michiaki*
RIST News, (58), p.25 - 32, 2015/01
The Japan Atomic Energy Agency (JAEA) are now developing WAZA-ARI for improvement of management of exposure doses due to CT examination under the joint research with the Oita University of Nursing and Health Sciences. The trial version of WAZA-ARI has been released on 21 December 2012. In trial version, users can perform dose assessment by using organ dose database based on the average adult Japanese male (JM-103) and female (JF-103) voxel phantoms and a 4 years old female voxel phantom (UFF4). The homepage of WAZA-ARI has been accessed over 1000 times per month and 28421 times by the end of September 2014. We are developing WAZA-ARI version 2 as the extension version of dose calculation functions of WAZA-ARI. WAZA-ARI version 2 will be released by the end of March 2015. In WAZA-ARI version 2. Users can upload dose calculation results to WAZA-ARI version 2 server, and utilize improvement of the dose management of patients and the optimization of CT scan conditions.
Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saishun; Hori, Toshihiko; Sawabe, Yuki; Chishiro, Etsuji; Fukuda, Shimpei; Hasegawa, Kazuo; Hirano, Koichiro; Kikuzawa, Nobuhiro; et al.
Physical Review Special Topics; Accelerators and Beams, 17(12), p.120101_1 - 120101_8, 2014/12
Times Cited Count：6 Percentile：40.35(Physics, Nuclear)We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.
Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki
JAEA-Data/Code 2014-017, 60 Pages, 2014/10
JAEA-Data-Code-2014-017.pdf:15.4MBJAEA-Data-Code-2014-017-appendix(CD-ROM).zip:0.62MB
International Commission on Radiological Protection (ICRP) determined reference phantoms based on physique and organ masses (physical characteristics) of Caucasian for dose assessment in the 2007 Recommendations. In internal dosimetry, the reference phantoms are used for calculation of specific absorbed fractions (SAFs). On the other hand, adult Japanese have smaller build than adult Caucasian, and organ masses are different from each other. SAFs depend on physical characteristics. Therefore, differences in physical characteristics between both races can influence dose coefficients. Then, SAFs of average adult Japanese male phantom, JM-103, were calculated by incorporating JM-103 into the general purpose radiation transport code, MCNPX2.6.0, and electron and photon SAFs were evaluated for 25 energies from 10 keV to 10 MeV and for combinations of 67 source regions and 41 target organs. The effect of the difference in build and organ masses between adult Japanese and Caucasian on SAFs was also examined by comparison between the calculated SAFs in this study and SAFs of the reference adult male phantom of ICRP. The SAFs of JM-103 calculated in this study are basic data for assessment of influence of difference in physical characteristics between the races on dose coefficients.
Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10
no abstracts in English
Fukui, Yuji*; Futatsukawa, Kenta*; Fang, Z.*; Kawamura, Masato*; Sato, Fumiaki; Shinozaki, Shinichi; Hori, Toshihiko; Chishiro, Etsuji; Suzuki, Hiroyuki
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1282 - 1284, 2014/08
In order to upgrade beam energy of linac from 181 MeV to 400 MeV, the ACS cavities and the new RF sources were installed in the maintenance period of summer of 2013. We started preparation of the 972 MHz RF Control systems, which consist of RF control network, Low Level RF control system, klystron power supply control system and cavity monitor system, from 2011 and had finished installing to all ACS stations in October, 2013. The ACS16 and 17 stations were used as a klystron test station and high power test for 972 MHz klystrons was done there for five months. The current status of RF control systems and the operating experience, mainly PLC control, are described on this report.
Sn conductor for ITER central solenoidTakahashi, Yoshikazu; Nabara, Yoshihiro; Ozeki, Hidemasa; Hemmi, Tsutomu; Nunoya, Yoshihiko; Isono, Takaaki; Matsui, Kunihiro; Kawano, Katsumi; Oshikiri, Masayuki; Uno, Yasuhiro; et al.
IEEE Transactions on Applied Superconductivity, 24(3), p.4802404_1 - 4802404_4, 2014/06
Times Cited Count：28 Percentile：74.04(Engineering, Electrical & Electronic)Japan Atomic Energy Agency (JAEA) is procuring all amounts of NbSn conductors for Central Solenoid (CS) in the ITER project. Before start of mass-productions, the conductor should be tested to confirm superconducting performance in the SULTAN facility, Switzerland. The original design of cabling twist pitches is 45-85-145-250-450 mm, called normal twist pitch (NTP). The test results of the conductors with NTP was that current shearing temperature (Tcs) is decreasing due to electro-magnetic (EM) load cycles. On the other hand, the results of the conductors with short twist pitches (STP) of 25-45-80-150-450 mm show that the Tcs is stabilized during EM load cyclic tests. Because the conductors with STP have smaller void fraction, higher compaction ratio during cabling is required and possibility of damage on strands increases. The technology for the cables with STP was developed in Japanese cabling suppliers. The several key technologies will be described in this paper.
Hori, Toshihiko; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; Oguri, Hidetomo; Futatsukawa, Kenta*; Fukui, Yuji*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1001 - 1003, 2014/06
no abstracts in English
