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Journal Articles

What can we measure by radiation measurement instruments?

Takeyasu, Masanori

Tomioka Hoshasen Joho Matome Saito (Internet), 2 Pages, 2017/01

Some radiation measurement instruments are lent out to the residents in Tomioka-machi, Fukushima. In this paper, it is explained that the kinds of those instruments, their purposes, the attention points on their uses and the interpretation of the measurement results by those instruments.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2014

Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Takeyasu, Masanori; Mizutani, Tomoko; Isozaki, Tokuju*; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; Nishimura, Tomohiro; et al.

JAEA-Review 2015-034, 175 Pages, 2016/03

JAEA-Review-2015-034.pdf:8.13MB

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 2014 to March 2015. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co. in March 2011.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2013

Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Takeyasu, Masanori; Mizutani, Tomoko; Isozaki, Tokuju; Morisawa, Masato; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; et al.

JAEA-Review 2014-042, 175 Pages, 2015/01

JAEA-Review-2014-042.pdf:10.89MB

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 2013 to March 2014. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Co. in March 2011.

Journal Articles

Estimation of dry deposition velocities of radionuclides released by the accident at the Fukushima Dai-ichi Nuclear Power Plant

Takeyasu, Masanori; Sumiya, Shuichi

Progress in Nuclear Science and Technology (Internet), 4, p.64 - 67, 2014/04

On the basis of I-131 measured after Fukushima primary nuclear power plant in nuclear fuel cycle engineering laboratory and atmosphere radioactive material concentration of cesium isotope and atmospheric deposition quantity data, the deposition velocity of atmosphere radioactive material to the surface was estimated. As the result, the deposition velocity was the 10$$^{-3}$$m/s order. It was the order equal to I-131 deposition velocity estimated after Chernobyl accident estimated from until now environmental radiation monitoring result around Tokai Nuclear Fuel Reprocessing Plant from the monitoring result in I-129 deposition velocity and this laboratory. It was guessed that it included the gaseous component for I-131 and cesium isotope discharged by Fukushima accident in atomic powered generation and that the deposition velocity varied by the ratio of the component.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2012

Sumiya, Shuichi; Watanabe, Hitoshi; Miyagawa, Naoto; Nakano, Masanao; Nakada, Akira; Fujita, Hiroki; Takeyasu, Masanori; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; et al.

JAEA-Review 2013-056, 181 Pages, 2014/03

JAEA-Review-2013-056.pdf:6.22MB

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 2012 to March 2013. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Co. in March 2011.

Journal Articles

Estimation of dose from the measurement results of airborne radionuclide concentrations following the Fukushima Dai-ichi Nuclear Power Plant accident; For the public around Tokai-mura, Ibaraki

Takeyasu, Masanori; Sumiya, Shuichi; Furuta, Sadaaki

Hoken Butsuri, 48(3), p.141 - 149, 2013/11

On the basis of airborne concentrations of radionuclides in the Nuclear Fuel Cycle Engineering Laboratories, JAEA, the committed effective dose to adult and committed equivalent dose to thyroid of infant by inhalation were estimated by setting the realistic parameters for indoor-outdoor air concentration ratio, inhalation rate and dose coefficient, and the margin of safety in projected dose was examined. As the results, the estimated doses were about 1/7 for the projected committed effective dose to adult and about 1/10 for the projected committed equivalent dose to thyroid of infant, respectively. These facts indicated that the projected dose had the degrees of safety margin of the factor of 7 for committed effective dose to adult and the factor of 10 for committed equivalent dose to thyroid of infant, respectively. It was the most important parameter for estimating the committed dose that the indoor-outdoor air concentration ratio.

JAEA Reports

Study on the determination of the variation of environmental $$gamma$$-ray dose rate due to radioactivity discharged from nuclear fuel cycle facility (Thesis)

Takeyasu, Masanori

JAEA-Review 2013-016, 92 Pages, 2013/07

JAEA-Review-2013-016.pdf:3.65MB

The following studies were carried out with the purpose that the variation of environmental $$gamma$$-ray dose rate was determined due to radioactivity released from nuclear fuel cycle facility; Development of calculation code system (SIERRA-II) in order to determine in quasi-real time the variation of environmental $$gamma$$-ray dose rate due to the operation of reprocessing facility, examination for determining the variation of the dose rate during the operation using SIERRA-II, measurement of the concentration of $$^{222}$$Rn decay products in rainwater, and construction of the wet scavenging model for the atmospheric $$^{222}$$Rn decay products, determination of the variation of environmental $$gamma$$-ray dose rate due to the released $$^{85}$$Kr during rainfall. By these studies, it became clear that the developed SIERRA-II could determined the variation of environmental $$gamma$$-ray dose rate during the operation of reprocessing plant with practical accuracy.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2011

Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Nagaoka, Mika; et al.

JAEA-Review 2013-009, 195 Pages, 2013/06

JAEA-Review-2013-009.pdf:3.35MB

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 2011 to March 2012. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in March 2011.

Journal Articles

Study of wet scavenging of atmospheric aerosols using $$^{222}$$Rn decay products in rainwater

Takeyasu, Masanori

Rainfall; Behavior, Forecasting and Distribution, p.105 - 121, 2012/10

The concentrations and the concentration ratios of individual short-lived $$^{222}$$Rn decay products ($$^{214}$$Pb and $$^{214}$$Bi) in rainwater were measured, and a scavenging model was designed for explaining the measurement results. The measurement was done at Kumatori-cho in Osaka, Japan by $$gamma$$-ray spectrometry using a low-background Ge detector. The dependence of the time variations of the concentrations and their ratios on rainfall rate was investigated. It was observed that the concentrations were negatively correlated with the rainfall rate in some rainfall events, and that there was no clear correlation in other rainfall events. The concentration ratios showed a weak negative correlation with the rainfall rate for most of the observed rainfall events.

JAEA Reports

ORION-WIN; A Computer code to estimate environmental concentration and radiation dose due to airborne discharge of radioactive materials from nuclear facilities

Takeyasu, Masanori; Onuma, Toshimitsu; Sumiya, Shuichi

JAEA-Data/Code 2012-021, 29 Pages, 2012/09

JAEA-Data-Code-2012-021.pdf:1.42MB

A computer code, ORION-WIN, has been developed to estimate environmental concentration and radiation dose to public due to airborne discharge of radioactive materials from multiple sources of nuclear fuel cycle facilities. The modified Gaussian plume model is applied to calculate atmospheric dispersion of the discharged radioactive material. The plume depletion processes such as gravitational settling, dry deposition, precipitation scavenging and radioactive decay are considered. Inhalation and oral intake are considered as internal pathways, and submersion in the radioactive cloud and external exposure to contaminated ground surface are considered as external pathways, respectively. Radiation dose to an individual is calculated. ORION-WIN is an updated version of ORION-II and runs on PC mounting Windows OS, and has a graphical user interface for inputting the parameters and referring output files.

JAEA Reports

ORION-WIN; A Computer code to estimate environmental concentration and radiation dose due to airborne discharge of radioactive materials from nuclear facilities

Takeyasu, Masanori; Onuma, Toshimitsu; Sumiya, Shuichi

JAEA-Data/Code 2012-011, 28 Pages, 2012/07

JAEA-Data-Code-2012-011.pdf:1.22MB

A computer code, ORION-WIN, has been developed to estimate environmental concentration and radiation dose to the public due to the airborne release of radioactive materials from multiple sources of nuclear fuel cycle facilities. The modified Gaussian plume model is applied to calculate atmospheric dispersion of the released radioactive material. The plume depletion processes such as gravitational settling, dry deposition, precipitation scavenging and radioactive decay are considered, and re-suspension from the ground and the produce of progeny from the parent radionuclides are also considered. Inhalation and oral intake are considered as internal pathways, and submersion in the radioactive cloud and external exposure to contaminated ground surface are considered as external pathways, respectively. Radiation dose to an individual is calculated.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2010

Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Kokubun, Yuji; et al.

JAEA-Review 2012-015, 166 Pages, 2012/05

JAEA-Review-2012-015.pdf:3.53MB

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 2010 to March 2011. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in 2011 March. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data exceeded the normal range of fluctuation by the accidental release was evaluated in the appendices.

Journal Articles

Special environmental monitoring around Tokai-mura after the accident of the Fukushima Dai-ichi Nuclear Power Station

Fujita, Hiroki; Nagaoka, Mika; Kono, Takahiko; Takeyasu, Masanori; Kawasaki, Masatsugu; Okura, Takehisa; Tsujimura, Norio; Sumiya, Shuichi; Momose, Takumaro; Furuta, Sadaaki

Proceedings of 13th International Congress of the International Radiation Protection Association (IRPA-13) (Internet), 7 Pages, 2012/05

The nuclear accident at Fukushima Dai-ichi Nuclear Power Station of Tokyo Electric Power Co. (TEPCO) was caused by the Tohoku District-off the Pacific Ocean Earthquake. Various kinds of radionuclides were released from the power station right after the accident occurred and then reached our laboratories. Therefore, environmental monitoring was reinforced by observation of air absorbed dose rate, periodic collection of airborne dust, precipitation. The collected samples were used to determine radioactivity of $$gamma$$ ray emitters by High pure Germanium semiconductor detector. Moreover, rainwater and humidity were collected to do the usual routine monitoring. In some samples, $$^{90}$$Sr, $$^{131}$$I, $$^{134}$$Cs and $$^{137}$$Cs were detected with radioactivity released from the Fukushima station. In other samples such as seawater, seabed soil and etc., similar radionuclides were detected including the influence of the accident.

Journal Articles

Results of environmental radiation monitoring at the Nuclear Fuel Cycle Engineering Laboratories, JAEA, following the Fukushima Daiichi Nuclear Power Plant accident

Takeyasu, Masanori; Nakano, Masanao; Fujita, Hiroki; Nakada, Akira; Watanabe, Hitoshi; Sumiya, Shuichi; Furuta, Sadaaki

Journal of Nuclear Science and Technology, 49(3), p.281 - 286, 2012/03

 Times Cited Count:18 Percentile:16.54(Nuclear Science & Technology)

As a response to the Fukushima Daiichi Nuclear Power Plant accident, emergency environmental radiation monitoring was performed at the Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency (JAEA). This paper provisionally describes the results of the monitoring including ambient radiation dose rate and radioactivity concentrations in airborne and fallout. The ambient radiation dose rate began to increase since about 1:00 on March 15 2011, and varied with three peak dose rate of several thousand $$mu$$Gy/h at 8:00 on March 15, at 5:00 on March 16, and at 4:00 on March 21. The variation over time in radioactivity concentrations in airborne and fallout almost showed the same tendency as that of the dose rate. The fallout of $$^{137}$$Cs for 1 month from March 15 to April 15 was about 120 times higher than that in May 1986 after the Chernobyl accident. The internal dose by inhalation was estimated from the airborne concentration observed.

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.

JAEA Reports

Results of the environmental radiation monitoring following the accident at the Fukushima Daiichi Nuclear Power Plant; Interim report (Ambient radiation dose rate, radioactivity concentration in the air and radioactivity concentration in the fallout)

Furuta, Sadaaki; Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Imaizumi, Kenji; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Mizutani, Tomoko; Morisawa, Masato; et al.

JAEA-Review 2011-035, 89 Pages, 2011/08

JAEA-Review-2011-035.pdf:2.97MB

As a correspondence to the accident at the Fukushima Daiichi Nuclear Power Plant, the environmental radiation monitoring was performed at the Nuclear Fuel Cycle Engineering Laboratories, JAEA. This report presented the measurement results of ambient radiation dose rate, radioactivity concentration in the air and radioactivity concentration in fallout and meteorological observation result until May 31, 2011. The ambient radiation dose rate increased, with the peak dose rate of several thousand nGy/h at 7 o'clock in March 15, at 5 o'clock in March 16, and at 4 o'clock in March 21. The variation on the radioactivity concentration in the air and in fallout showed the almost same tendency as that of the dose rate. The concentration ratio of I-131/Cs-137 in the air increased to about 100. The dose was estimated resulting from internal exposure due to inhalation.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2009

Sumiya, Shuichi; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Kokubun, Yuji; et al.

JAEA-Review 2011-004, 161 Pages, 2011/03

JAEA-Review-2011-004.pdf:4.09MB

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 2009 to March 2010. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes.

Journal Articles

Measurement of environmental $$gamma$$-ray dose rate around the Nuclear Fuel Cycle Engineering Laboratories, JAEA

Mizutani, Tomoko; Onuma, Toshimitsu; Sugai, Masamitsu*; Watanabe, Hajime*; Morisawa, Masato; Takeyasu, Masanori; Sumiya, Shuichi

Progress in Nuclear Science and Technology (Internet), 1, p.380 - 383, 2011/02

The Nuclear Fuel Cycle Engineering Laboratories (NCL), JAEA operates the Tokai Reprocessing Plant (TRP), plutonium fuel fabrication facilities and the supplemental facilities. In the terrestrial environment, environmental $$gamma$$-ray dose rate was measured continuously using an energy-thermo-compensation-type NaI(Tl) scintillation counter. The data of environmental dose rate measured in 5 monitoring stations and 8 monitoring posts were collected and analyzed to monitor on real-time. This paper summarizes the monitoring data of environmental dose rate around the NCL during the past 10 year (fiscal 1998-2007). The monthly average of the environmental dose rate for all monitoring stations and posts were in the range of 31-48 nGy h$$^{-1}$$, except the value influenced by the criticality accident at the JCO in 1999. The long-term variation in the environmental dose rate was not found. The cases of the short-term increases occurred by the operations of the facilities in the NCL were concluded by the discharges of $$^{85}$$Kr from the TRP, transportation of MOX fuels or radioactive solid wastes, X-ray generator to calibrate the radiation monitoring instruments. The other cases to affect the change of the environmental dose rate were the scavenging of the airborne natural radionuclides, a patient cured by the radiation therapy and the shield effect by cars.

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

Development of calculation code for estimating radiation dose for hypothetical accident of nuclear facility considering radioactive decay chain during atmospheric dispersion of released radionuclides

Takeyasu, Masanori; Nakano, Masanao; Sumiya, Shuichi; Nemoto, Hiromi*; Kanno, Mitsuhiro*; Kurosawa, Naohiro*

Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 4 Pages, 2010/05

The dose to the public at hypothetical accident of nuclear facility is estimated on the basis of the method described in the Japanese meteorological guideline. However, the radioactive decay during atmospheric dispersion of released radionuclide is not considered in the calculation formula in the guideline. Therefore, when the radionuclide of the half life such as a few min is released, the dose may be excessively over-estimated. In this study, the calculation code was developed which could consider the radioactive decay of the released radionuclide and the generation of the product. The dose calculated on the basis of the developed code was compared with that on the basis of the guideline.

60 (Records 1-20 displayed on this page)