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JAEA Reports

Planning and implementation of environmental radiation monitoring

Takeishi, Minoru

JAEA-Review 2020-077, 388 Pages, 2021/05

JAEA-Review-2020-077.pdf:18.48MB

Japan Atomic Energy Agency (JAEA) have implemented environmental radiation monitoring since 1960s around different kinds of nuclear facilities such as research reactors, MOX fuel fabrication development facilities and the first spent fuel reprocessing facility for commercial NPPs and so on. I summarize the environmental monitoring methodology from planning to evaluation comprehensively as a guide book based on our experience and referring to the latest information. This guide book contained various basic knowledge about history of environmental radiation surveillances, techniques of radiation measurement and analysis of environmental samples such as airborne materials, precipitation, fallout, soil, sediment in river and lake, drinking water, terrestrial water, vegetables, milk, pasture, sea water, seabed sediment, marine product, index samples, and including with related to fundamental knowledges like an exposure evaluation for the public and quality assurance(QA), and some regulations. In particular, I include the emergency environmental radiation monitoring with response to the accident of Chernobyl Nuclear Power Plant and Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station. Finally, I note some topics on the environmental impact study that I have experienced.

Journal Articles

Rapid tritium analysis for marine products in the coastal area of Fukushima

Kuwata, Haruka*; Misono, Toshiharu; Fujiwara, Kenso; Takeishi, Minoru; Manabe, Sachi*; Kitamura, Akihiro

Radiation Environment and Medicine, 9(1), p.28 - 34, 2020/02

The analysis of tritium in aquatic biota is one of the most important research areas in Fukushima. The conventional method for measuring the concentration of tritium consists of complicated pretreatment procedures and requires skillful techniques as well as a significant amount of time. Consequently, there are only a few reports on tritium monitoring data in marine products from the coast of Fukushima. In this study, we measured the Tissue Free Water Tritium (TFWT) and Organically Bound Tritium (OBT) in flounders collected from the coast of Fukushima to examine the impacts of the nuclear accident on aquatic biota. The study was done for a period of 4 years; from 2015 to 2018. The conventional method of analysis was firstly used, after which the method was modified by improving the freeze-drying and combustion water recovery processes. Results from both methods show that the most of the concentrations of the TFWT and OBT in the flounder were below the detection or quantitative limit. The effect of the nuclear accident on humans, through internal exposure, was also examined and found to be negligible. Although some uncertainties exist due to the short cut of the processes, the modified version could be considered an effective and practical approximate method.

Journal Articles

Establishment of a Laboratory for $$gamma$$-ray Spectrometry of Environmental Samples Collected in Fukushima

Saegusa, Jun; Yoda, Tomoyuki; Maeda, Satoshi; Okazaki, Tsutomu; Otani, Shuichi; Yamaguchi, Toshio; Kurita, Yoshiyuki; Hasumi, Atsushi; Yonezawa, Chushiro*; Takeishi, Minoru

Proceedings of 14th International Congress of the International Radiation Protection Association (IRPA-14), Vol.3 (Internet), p.1078 - 1085, 2017/11

After the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in March 2011, the Japan Atomic Energy Agency has newly set up a laboratory for radioactivity analysis in Fukushima. At the laboratory, radioactivity concentrations of environmental samples such as soil, water, dust filter, plant, etc., approximately 1,000 samples in a month, are measured with high-resolution $$gamma$$-ray spectrometry systems. The systems employ n-type HPGe detectors from Ortec. Since September 2012, characterization and upgrade of the systems have been performed aimed at enhancing reliability of analysis and convenience of customers. Resolving both systematic and technical issues, the laboratory has been accredited the ISO/IEC 17025 standard as a testing laboratory for radioactivity analysis.

Journal Articles

Using two detectors concurrently to monitor ambient dose equivalent rates in vehicle surveys of radiocesium contaminated land

Takeishi, Minoru; Shibamichi, Masaru; Malins, A.; Kurikami, Hiroshi; Murakami, Mitsuhiro*; Saegusa, Jun; Yoneya, Masayuki

Journal of Environmental Radioactivity, 177, p.1 - 12, 2017/10

AA2016-0534.pdf:1.79MB

By convention radiation measurements from vehicle-borne surveys are converted to the dose rate at 1 m above the ground in the absence of the vehicle. To improve the accuracy of the converted results from vehicle-borne surveys, we investigated combining measurements from two detectors mounted on the vehicle at different heights above the ground. A dual-detector setup was added to a JAEA monitoring car and compared against hand-held survey meter measurements in Fukushima Prefecture. The dose rates obtained by combining measurements from two detectors were within $$pm$$20% of the hand-held reference measurements. The combined results from the two detectors were more accurate than those from either the roof-mounted detector, or the detector inside the vehicle, taken alone. When radiocesium is deficient on a road compared to the adjacent land, mounting detectors high on vehicles yields dose rates closer to the values adjacent to the road. We also investigated mounting heights for vehicle-borne detectors using Monte Carlo $$gamma$$-ray simulations.

Journal Articles

Analysis of ambient-dose-rate trends in Fukushima; Ecological half-life, effect of snow covering

Saegusa, Jun; Yoda, Tomoyuki; Murakami, Mitsuhiro; Takeishi, Minoru

Kankyo Hoshano Josen Gakkai-Shi, 5(2), p.79 - 93, 2017/06

After the Fukushima Daiichi Nuclear Power Plant (NPP) accident in March 2011, environmental radiation monitoring works have been continuously conducted throughout the Fukushima prefecture of Japan. Five-year transitions of ambient dose rates at 15 locations 20-60 km away from the NPPs were precisely analyzed to investigate their chronological change. Measured dose rates were successfully fitted into a function consisting of a factor reflecting the physical decay of radiocesium and the other component such as the weathering effect. The ecological half-lives derived from the function ranged from 3 to 27 years (average 10 years). The radiation shielding effect by snow covering was also studied with the obtained functions. Due to the effect, dose rates were lowered by 15-50% by 20-cm-deep snow covering, and the ambient doses integrated over the five years were found to decrease by up to 7% compared to those without the snow covering that can be predicted from the fit function.

Journal Articles

Coupling the advection-dispersion equation with fully kinetic reversible/irreversible sorption terms to model radiocesium soil profiles in Fukushima Prefecture

Kurikami, Hiroshi; Malins, A.; Takeishi, Minoru; Saito, Kimiaki; Iijima, Kazuki

Journal of Environmental Radioactivity, 171, p.99 - 109, 2017/05

 Times Cited Count:6 Percentile:31.3(Environmental Sciences)

A modified diffusion-sorption-fixation model (mDSF) is proposed to describe the vertical migration of radiocesium in soils following fallout. The model introduces kinetics for reversible sites, meaning that the exponential-shape radiocesium distribution can be reproduced immediately following fallout. The initial relaxation mass depth of the distribution is determined by the diffusion length, which depends on the distribution coefficient, sorption rate and dispersion coefficient. The model captures the long tails of the radiocesium distribution at large depths. These tails are caused by different rates for kinetic sorption and desorption.

Journal Articles

Study on pretreatment methods using a rapid combustion apparatus for the analyses of Organically Bound Tritium (OBT) in environmental samples

Manabe, Sachi; Matsubara, Natsumi; Saegusa, Jun; Takeishi, Minoru

KEK Proceedings 2016-8, p.281 - 285, 2016/10

no abstracts in English

Journal Articles

Environmental radiation monitoring

Takeishi, Minoru

Hosha Kagaku No Jiten, p.200 - 201, 2015/09

I described an environmental radiation monitoring in the radiochemical dictionary. The purpose of an environmental radiation monitoring is to evaluate radiation effect for the public through the measurements of radiation and radioactivity in the environment. There are two different situations regarding environmental radiation monitoring, in normal and in emergency. The purpose, method and notice are described in this explanation.

JAEA Reports

SIERRA-II; Simulation system (II) for emergency dose by released radioactive substances

Takeyasu, Masanori; Takeishi, Minoru*

JAEA-Data/Code 2011-019, 23 Pages, 2012/02

JAEA-Data-Code-2011-019.pdf:2.95MB

A computer code system (SIERRA-II) has been developed to estimate the environmental radiological impact of accidental releases of radionuclides from a nuclear facility in real time. The SIERRA-II is based on a three-dimensional mass-conserving wind field model and a particle dispersion model with a nesting function to calculate with high spatial resolution in the vicinity of the facility. Input includes on-line local meteorological and effluent data observed and monitored at the site of the facility, and local meteorological data as predicted by an atmospheric dynamic model. The SIERRA-II was validated using environmental monitoring data for ambient dose rate as observed at monitoring posts around the Tokai Reprocessing Plant when Kr-85 was discharged during its operation. The observed increase of the dose rate was simulated well. The agreement of calculated and observed dose rate was within a factor of 5 for 74 % of observations.

Journal Articles

Estimation of $$^{222}$$Rn concentration in the lower troposphere during precipitation using wet scavenging model for its decay products

Takeyasu, Masanori; Takeishi, Minoru

Asian Journal of Atmospheric Environment, 4(1), p.20 - 25, 2010/06

The atmospheric $$^{222}$$Rn concentration in rain clouds was estimated by using the wet scavenging model of its decay products with the observed data of the environmental radiation. The origin of the $$^{222}$$Rn was also discussed, when a large increase of the radiation was observed. The estimation was done for a rainfall event on Dec. 26-27, 2003, when a large increase of the radiation was observed in Tokai-mura in Ibaraki, Japan. From a backward trajectory analysis, the origin of $$^{222}$$Rn atoms for that event was back-tracked to the northeastern part of China, and it was expected that the large amount of $$^{222}$$Rn exhalated in the northeastern part of China was transported to Tokai-mura by the Eurasian continental air mass.

Journal Articles

Determination of the variation of environmental radiation due to the ground deposition of atmospheric $$^{222}$$Rn decay products during rainfall; Utilization of the correlation between the variations observed at neighboring monitoring posts

Takeyasu, Masanori; Onuma, Toshimitsu; Takeishi, Minoru

Journal of Radioanalytical and Nuclear Chemistry, 284(3), p.635 - 639, 2010/03

 Times Cited Count:2 Percentile:19.27(Chemistry, Analytical)

The increase of environmental radiation dose rate during rainfall at environmental monitoring posts (MPs) was calculated by using the correlation relationship with the dose rate at the neighboring MP. The calculated dose rate agreed with the observed one within less than 20% of the maximum increase height of the observed one for each rainfall. Furthermore, when the dose rate increased due to $$^{85}$$Kr discharged from the Tokai Reprocessing Plant (TRP) at the environmental monitoring station (MS) downwind of the stack during rainfall, the dose rate due to the $$^{85}$$Kr was tried to discriminate. The discriminated dose rate agreed with that calculated by the atmospheric dispersion calculation code system, SIERRA-II, using stack monitor data and local meteorological observation data.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2008

Takeishi, Minoru; Sumiya, Shuichi; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Isozaki, Hisaaki*; Isozaki, Tokuju; Morisawa, Masato; Fujita, Hiroki; et al.

JAEA-Review 2009-048, 177 Pages, 2009/12

JAEA-Review-2009-048.pdf:19.3MB
JAEA-Review-2009-048(errata).pdf:0.12MB

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 2008 to March 2009. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes.

JAEA Reports

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2008

Takeishi, Minoru; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Kono, Takahiko; Hiyama, Yoshinori; Fujii, Jun*; Kikuchi, Masaaki*; Sagawa, Fumiaki*; Otani, Kazunori*

JAEA-Review 2009-039, 131 Pages, 2009/12

JAEA-Review-2009-039.pdf:15.22MB

Based on the regulations (the safety regulation of Tokai reprocessing plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, and the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and byelaw of Ibaraki prefecture), this report describes the effluent control results of liquid waste discharged from the JAEA's Nuclear Fuel Cycle Engineering Laboratories in the fiscal year 2008, from 1st April 2008 to 31st March 2009. In this period, the concentrations and the quantities of the radioactive liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other facilities were much lower than the authorized limits of the above regulations.

Journal Articles

Monitoring of low-level radioactive liquid effluent in Tokai reprocessing plant

Mizutani, Tomoko; Koarashi, Jun; Takeishi, Minoru

Journal of Nuclear Science and Technology, 46(7), p.665 - 672, 2009/07

 Times Cited Count:8 Percentile:53.11(Nuclear Science & Technology)

Tokai reprocessing plant (TRP) has discharged low-level liquid-wastes to the Pacific Ocean since the start of its operation in 1977. We have performed the liquid effluent monitoring to realize an appropriate radioactive discharge control. Comparing simple and rapid analytical methods with labor-intensive radiochemical analyses demonstrated that the gross-alpha and gross-beta activities agreed well with the total activities of plutonium (Pu) isotopes and major beta-emitters (e.g. $$^{90}$$Sr and $$^{137}$$Cs), respectively. The records of the radioactive liquid discharge from the TRP showed that the normalized releases of all nuclides, except for $$^{3}$$H, were three or four orders of magnitude lower than those from the oversea reprocessing plants. This was probably due to the installation of multi-stage evaporators in the liquid waste treatment process in 1980. Plutonium radioactivity ratios ($$^{238}$$Pu/$$^{239+240}$$Pu) of the liquid effluents were determined to be 1.3-3.7, while those of the seabed sediment samples collected around the discharge point were 0.003-0.059, indicating no remarkable accumulation of Pu in the regional aquatic environment. The annual public doses were estimated to be less than 0.2 $$mu$$Sv y$$^{-1}$$ from the aquatic pathway. Thus, we concluded that there were no significant radiological effects on the aquatic environment and the public during the past 30-year operation of the TRP.

Journal Articles

Survey of transuranium nuclides in low level liquid effluents from the Tokai Reprocessing Plant

Kono, Takahiko; Hiyama, Yoshinori; Nakano, Masanao; Takeishi, Minoru

Hoken Butsuri, 44(2), p.209 - 217, 2009/06

We surveyed the concentration levels of TRU nuclides in the effluent discharged from the Tokai Reprocessing Plant (TRP) from 1998 to 2003 as the former stage of FBR cycle. It was confirmed that the TRU nuclides concentration discharged from the TRP was 1/150 $$sim$$ 1/10$$^{6}$$ much lower than the concentration limit authorized in governmental notification. Then, we compared the normalized discharge amounts from the TRP with those from the foreign reprocessing plants. As a result, the TRP has reduced the amounts of discharged nuclides, by the order of 1/100 $$sim$$ 1/10$$^{7}$$ compared with foreign ones. This survey provided the important and basic data in order to compare the liquid discharges of TRU nuclides in FBR and the present nuclear fuel cycles.

Journal Articles

Tritium concentration and diffusion in seawater discharged from Tokai reprocessing plant

Nakano, Masanao; Kokubun, Yuji; Takeishi, Minoru

Hoken Butsuri, 44(1), p.60 - 65, 2009/03

The tritium concentrations in seawater collected around the Tokai Reprocessing Plant (TRP) were measured for 10,800 samples in 30 years from 1978. The tritium concentration, dillution factor and diffusion situation were investigated. As a result, the tritium was occationaly detected due to the discharge from TRP. But it was considered to be the result of normal diffusion assumed in the safety assessment. It was confirmed that the tritium concentration was much lower than the concentration limit defined in the law and that it was not concern of environmental safety.

Journal Articles

Analytical method of $$gamma$$ emitters in seawater using coprecipitation with nickel hexacyanoferrate(II) and iron(III) hydroxide

Nakano, Masanao; Kokubun, Yuji; Sasaki, Takeshi*; Takeishi, Minoru

Radioisotopes, 58(2), p.61 - 69, 2009/02

The analytical yield of $$gamma$$ emitters in seawater by coprecipitation method with nickel hexacyanoferrate(II) and iron(III) hydroxide was confirmed using spiked radioisotope ($$^{137}$$Cs) and stable elements. Ninety-nine % of spiked $$^{137}$$Cs was adsorbed on nickel hexacyanoferrate(II), and 88 $$sim$$ 94% of spiked Ce, Co, Mn, Ru, Zn, Zr was adsorbed on iron(III) hydroxide. This analytical method is considered tobe very efficient and practical for environmental radiation monitoring from the view of quick and simple operation, especially easy analysis of plural samples.

JAEA Reports

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2007

Takeishi, Minoru; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Kono, Takahiko; Hiyama, Yoshinori; Fujii, Jun*; Kikuchi, Masaaki*; Sagawa, Fumiaki*; Otani, Kazunori*

JAEA-Review 2008-060, 131 Pages, 2008/12

JAEA-Review-2008-060.pdf:13.33MB

Based on the regulations (the safety regulation of Tokai reprocessing plant, the safety regulation of nuclear fuel material usage facilities, radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, and the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and byelaw of Ibaraki prefecture), this report describes the effluent control results of liquid waste discharged from the JAEA's Nuclear Fuel Cycle Engineering Laboratories in the fiscal year 2007, from 1st April 2007 to 31st March 2008. In this period, the concentrations and the quantities of the radioactive materials discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other facilities were much lower than the authorized limits of the above regulations.

Journal Articles

Tritium concentration in seawater and its diffusion around Tokai reprocessing plant

Nakano, Masanao; Kokubun, Yuji; Kono, Takahiko; Takeishi, Minoru

Dai-50-Kai Kankyo Hoshano Chosa Kenkyu Seika Rombun Shorokushu (Heisei-19-Nendo), p.53 - 54, 2008/12

The tritium concentrations in seawater collected around the Tokai Reprocessing Plant (TRP) were measured for 10,800 samples in 30 years from 1978. The tritium concentration, dillution factor and diffusion situation were investigated. As a result, the tritium was occationaly detected due to the discharge from TRP. But it was considered to be the result of normal diffusion assumed in the safety assessment. It was confirmed that the tritium concentration was much lower than the concentration limit defined in the law and that it was not concern of environmental safety.

Journal Articles

Rapid detection and estimation of an unexpected atmospheric release of $$^{129}$$I

Koarashi, Jun; Mikami, Satoshi; Akiyama, Kiyomitsu; Takeishi, Minoru

Hoken Butsuri, 43(4), p.366 - 370, 2008/12

A sampling system was designed to detect rapidly an unexpected release of $$^{129}$$I during a weekly batch-sampling of a stack gas. The system consisted mainly of a sampling unit and an iodine monitor with an NaI(Tl) scintillation detector. A relationship between in situ count rate of the monitor and $$^{129}$$I activity collected in the sampling unit was derived from several set of data obtained with the system in the Tokai reprocessing plant. The system and relationship allowed us to estimate the amount of $$^{129}$$I release at an arbitrary time during the batch-sampling. A different iodine monitor with a Ge detector was also tested to overcome a difficulty in selective measurement of $$^{129}$$I with the NaI(Tl) scintillation detector in the presence of $$^{85}$$Kr in the target gas. The test demonstrated a feasibility of the real-time, $$^{85}$$Kr-interference-free monitoring of atmospheric $$^{129}$$I release.

121 (Records 1-20 displayed on this page)