Omori, Yasutaka*; Hosoda, Masahiro*; Takahashi, Fumiaki; Sanada, Tetsuya*; Hirao, Shigekazu*; Ono, Koji*; Furukawa, Masahide*
Journal of Radiological Protection, 40(3), p.R99 - R140, 2020/09
UNSCEAR and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation and ingestion from natural sources. In this study, radiation doses from natural radiation sources in Japan were reviewed with the latest knowledge and data. Total annual effective dose from cosmic-ray exposure can be evaluated as 0.29 mSv. The annual effective dose from external exposure to terrestrial radiation for Japanese population can be evaluated as 0.33 mSv using the data of nationwide survey by the National Institute of Radiological Sciences. The Japan Chemical Analysis Center (JCAC) performed the nationwide radon survey using a unified method for radon measurements in indoor, outdoor and workplace. The annual effective dose for radon inhalation was estimated using a current dose conversion factor, and the values were estimated to be 0.50 mSv. The annual effective dose from thoron was reported as 0.09 mSv by UNSCEAR and then the annual effective dose from inhalation can be described as 0.59 mSv. According to the report of large scale survey of foodstuff by JCAC, the effective dose from main radionuclides due to dietary intake can be evaluated to be 0.99 mSv. Finally, Japanese population dose from natural radiation can be assessed as 2.2 mSv which is near to the world average value of 2.4 mSv.
Nippon Genshiryoku Gakkai-Shi, 61(4), p.270 - 272, 2019/04
no abstracts in English
Nippon Genshiryoku Gakkai-Shi, 61(4), p.347 - 348, 2019/04
This article is published in a special feature in commemoration of the 60th anniversary of the Atomic Energy Society of Japan. The article is the contents that "I look back on this, and surveys the future", by chairwoman of Ethics Committee.
Naraha Center for Remote Control Technology Development, Fukushima Research Insitute
JAEA-Review 2018-014, 52 Pages, 2018/12
The Naraha Remote Technology Development Center (Naraha Center) consists of a mock-up test building and a research management building, and various test facilities necessary for the decommissioning work after the accident of TEPCO Fukushima Daiichi Nuclear Power Station are installed. Using these test facilities, a wide range of users, such as companies engaged in decommissioning work, research and development institutions, educational institutions, etc., can efficiently develop robots through characterization and performance evaluation of remote-controlled robots. Furthermore, it is possible to make various uses such as exhibitions that many companies have met together, experts' meetings on decommissioning. This report summarizes the activities of the Naraha Center such as development of remote control technologies, maintenance and training of remote control equipment for emergency response, use of component test areas, and so on in FY2016.
Khim, B.-K.*; Otosaka, Shigeyoshi; Park, K.-A.*; Noriki, Shinichiro*
Ocean Science Journal, 53(1), p.17 - 29, 2018/03
Distribution of carbon and nitrogen stable isotope ratios (C, N) in sinking particles collected in four stations in the Japan Sea was summarized. The C and N values in the sinking particles showed a clear seasonal variation, which agreed well with the variation in the chlorophyll a concentration in the surface seawater and in the sinking flux of biogenic particles. In particular, during the highly productive season of phytoplankton, a remarkable isotopic fractionation of N was found in the sinking particles, and it was inferred that the fractionation indicates the degree of nitrogen uptake by diatoms in the surface layer. These results are helpful information for linking the phenomenon in the ocean surface and the isotopic information recorded in the seafloor.
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%.
Gijutsushi, 29(11), p.12 - 15, 2017/11
We visited Onagawa NPP and discussed with the workers, for study of good practices at this plant, avoided severe accident, when the 3.11 earthquakes and tsunami disaster occurred. It was learned a part of background of the good practices, by discussion about organizational culture included in attitude for safety, philosophy of management, inheritance technology, and so on. It is important that we inform the knowledge leading safety culture analyzed from their experience to public, as professional engineer.
Nippon Genshiryoku Gakkai-Shi, 59(4), p.192 - 193, 2017/04
The institution of Professional Engineers, Japan (lPEJ), and the activity of contribution to society of IPEJ after the Fukushima-Daiichi Nuclear Power Plant accident were described.
Ishihara, Keisuke; Kanazawa, Shingo; Kozawa, Masachiyo; Mori, Masakazu; Kawahara, Takahiro
JAEA-Technology 2017-002, 27 Pages, 2017/03
At radioactive waste management facilities in the Nuclear Science Research Institute, solid radioactive wastes are stored by using containers such as 200L drums and pallets to tier containers in 2 to 4 stacks in the height direction in waste storage facilities (Waste Storage Facility No.1, Waste Storage Facility No.2 and Waste Size Reduction and Storage Facility). On March 11, 2011, the Great East Japan Earthquake was happened, and some waste packages dropped from their pallets and large number of waste packages moved from their original position and inclined due to the influence of the earthquake in the waste storage facilities. There was no experience of rearrangement works to set those dropped and unbalanced waste packages in their original position and it was necessary to prepare detailed work procedures and progress for this task to prevent the occurrence of industrial accidents. Therefore, we prepared detailed work manual and repeatedly carried out mock-up test. And then, we started rearrangement work from April 2011 after confirmation of workers skill and adequacy of the work manual. Finally, all rearrangement works for stored waste packages took about four and half years and were completed in September 2015 without any accident and shutdown of storage function. This report summarizes the countermeasures to reduce exposure doses of workers and to prevent the occurrence of industrial accidents during the rearrangement works.
Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki
JAEA-Data/Code 2016-013, 48 Pages, 2016/12
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.
Hoshasen, 41(2), p.89 - 92, 2016/03
Professional Engineer is the national qualification stipulated by the Professional Engineer Act. A Professional Engineer in this Act means a person who conducts business on matters of planning, research, design, analysis, testing, evaluation or guidance thereof, which requires application of extensive scientific and technical expertise, and has three obligation and two responsibility related to engineer ethic. A technical discipline for nuclear and radiation technology in 2004, was established for the purpose of upgrading the skills of engineers in nuclear technology fields, utilizing their ability in nuclear safety regulation fields, and further strengthening safety management system in each entity. The activity of the nuclear and radiation professional engineers for the past 10 years was evaluated. For the next ten years, awareness of the role of the professional engineer to talk with general public is needed, and it is important to continue professional development.
Gijutsushi, 27(11), p.8 - 11, 2015/11
Various analysis reports focused on Fukushima Daiichi Nuclear Power Plant disaster have been published from government, national diet, private group and Tokyo electric power company. Japan Health Physics Society (JHPS) analyzed these reports on perspective of radiation protection, and has reported towards the national and international society as "second-order recommendation report". What are radiation protection issues that have been found from these analysis reports? What is the direction of the goal of radiation protection system at the time of nuclear accident? From the results of these analyzes, many challenges have been found in current nuclear disaster prevention system.
Takahara, Shogo; Iijima, Masashi; Shimada, Kazumasa
Hoken Butsuri, 50(3), p.172 - 181, 2015/09
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
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.
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.
Sato, Kaoru; Noguchi, Hiroshi; Emoto, Yutaka*; Koga, Sukehiko*; Saito, Kimiaki
Radiation Protection Dosimetry, 123(3), p.337 - 344, 2007/02
A Japanese adult male voxel (volume pixel) phantom (hereinafter referred to as the JM phantom) was constructed on the basis of CT images of a healthy Japanese adult male volunteer. Body characteristics of the JM phantom were compared with those of a voxelized MIRD5 type phantom and a Japanese adult male voxel phantom which was previously developed. The voxel size of the JM phantom is 0.980.981 mm. The shapes of organs of the JM phantom, even for small or complicated organs, such as thyroid and stomach, are more realistically reproduced as compared with the previous Japanese voxel phantom (voxel size: 0.980.9810 mm). Photon self-absorbed fractions for brain, kidneys, spleen, pancreas, thyroid and urinary bladder wall of JM were evaluated and were compared with those of the other phantoms. In consequence, it was suggested that the mass, shape and thickness of organs are important factors for the determination of self-absorbed fractions.
Otosaka, Shigeyoshi; Amano, Hikaru; Ito, Toshimichi; Kawamura, Hideyuki; Kobayashi, Takuya; Suzuki, Takashi; Togawa, Orihiko; Chaykovskaya, E. L.*; Lishavskaya, T. S.*; Novichkov, V. P.*; et al.
Journal of Environmental Radioactivity, 91(3), p.128 - 145, 2006/00
Distributions of radionuclides (Sr, Cs and Pu) in seabed sediment in the Japan Sea were observed during 1998-2002. Observed inventories of anthropogenic radionuclides in sediment ranged 0.1-86 Bq m for Sr, 23-379 Bq m for Cs and 0.1-86 Bq m for Pu. In the deep part ( 2 km depth) of the western Japan Basin, Pu/Cs inventory ratios were larger than those in the central Yamato Basin although inventories of radionuclides were not different between basins. The higher Pu/Cs ratios in the western Japan Basin were derived by the production of Pu-enriched particle in the surface layer and effective sinking of particulate materials in this region. In the marginal Yamato Basin and the Ulleung Basin, both inventories and Pu/Cs ratios in sediment were larger than those in the central Yamato Basin. In the eastern/southern Japan Sea, it was suggested that the supply of particulate radionuclides by the TWC enhanced accumulation of radionuclides in this region.
Senju, Tomoharu*; Isoda, Yutaka*; Aramaki, Takafumi*; Otosaka, Shigeyoshi; Fujio, Shinzo*; Yanagimoto, Daigo*; Suzuki, Takashi; Kuma, Kenshi*; Mori, Kosuke*
Journal of Oceanography, 61(6), p.1047 - 1058, 2005/12
The detail structure of the Bottom Water in the Japan Sea was revealed by the hydrographic observations. The Yamato Basin Bottom Water (YBBW) exhibits higher temperature, lower dissolved oxygen, and higher nutrients concentrations than those in the Japan Basin Bottom Water (JBBW). Both Bottom Waters meet around the boundary region between the Yamato and the Japan Basins, and form a clear benthic front. It is inferred from the property distributions that the JBBW flowing into the Yamato Basin is trapped by the cyclonic circulation in the basin, and modified to the YBBW in the course of the circulation through the vertical diffusion, geothermal heating and oxygen consumption. The thermal balance of in the YYBW was examined using a box-model. The results show that the effect of geothermal heating has about 70 per-cent of magnitude to the vertical thermal diffusion and both terms cancel the advection term of the cold JBBW from the Japan Basin. The box-model also estimated the averaged residence time for the YBBW was 9.1 years.
Isotope News, (617), p.20 - 24, 2005/09
no abstracts in English
Jikken Rikigaku, 5(1), P. 64, 2005/03
no abstracts in English