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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.

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.

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

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

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

Re-evaluation of a method for monitoring airborne radioiodine discharge and its contribution to development of an advanced method

Koarashi, Jun; Mikami, Satoshi; Miyauchi, Toru; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Nakada, Akira; Akiyama, Kiyomitsu; Momose, Takumaro

JAEA-Technology 2010-039, 34 Pages, 2010/12

JAEA-Technology-2010-039.pdf:1.13MB
JAEA-Technology-2010-039(errata).pdf:0.08MB

The current methodology for monitoring airborne radioiodine at the Tokai reprocessing plant (TRP) was reviewed, and some investigations were made to re-evaluate collection and measurement techniques in the methodology. The investigations focused particularly on: (1) in situ collection efficiency of an iodine sampler for $$^{129}$$I and its dependence on sampling flow rate; (2) evaluation of $$^{129}$$I and $$^{131}$$I activities collected in an activated charcoal cartridge; (3) $$^{129}$$I collection capacity of an activated charcoal cartridge under reprocessing off-gas conditions; and (4) real-time monitoring system for $$^{129}$$I in airborne effluent. The results obtained gave not only the validity of the TRP's monitoring method, but also technical aspects required for establishing a more reliable and effective monitoring method for radioiodine isotopes.

Journal Articles

The Report of Health Physics 2010 Seminar

Nakada, Akira

Hoken Butsuri, 45(4), p.323 - 327, 2010/12

no abstracts in English

JAEA Reports

Radioactive airborne effluent discharged from Tokai reprocessing plant; 1998-2007

Nakada, Akira; Miyauchi, Toru; Akiyama, Kiyomitsu; Momose, Takumaro; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Otomo, Hiroyuki*

JAEA-Data/Code 2008-018, 134 Pages, 2008/10

JAEA-Data-Code-2008-018.pdf:3.23MB

This report provides the data set of atmospheric discharges from Tokai reprocessing plant in Tokai-mura, Japan over the period from 1998 to 2007. Daily and weekly data are shown for $$^{85}$$Kr that is continuously monitored and for the other nuclide (Alpha emitters, Beta emitters, $$^{3}$$H, $$^{14}$$C, $$^{129}$$I, $$^{131}$$I) whose activities are evaluated based on weekly batch-samplings, respectively. The data contained in this report are expected to apply for studying the behavior of the radioactive airborne effluent in the environment.

Journal Articles

Monitoring methodologies and chronology of radioactive airborne releases from Tokai reprocessing plant

Koarashi, Jun; Mikami, Satoshi; Nakada, Akira; Akiyama, Kiyomitsu; Kobayashi, Hirohide; Fujita, Hiroki; Takeishi, Minoru

Journal of Nuclear Science and Technology, 45(Suppl.5), p.462 - 465, 2008/06

 Times Cited Count:5 Percentile:60.16(Nuclear Science & Technology)

Tokai reprocessing plant (TRP) has released radionuclides such as $$^{3}$$H, $$^{14}$$C, $$^{85}$$Kr and $$^{129}$$I into the atmosphere since the start of operation in 1977. We have established the monitoring methodologies for these nuclides, to realize an appropriate and continuous radioactive discharge control. The methodologies having various special technical considerations for matching the monitoring of reprocessing off-gas, were summarized in this paper. Briefly, $$^{3}$$H was collected by a cold-trap technique and the concentration was evaluated being independent of the water collection efficiency; $$^{14}$$C was collected by a monoethanolamine bubbler and then measured by liquid scintillation counting without any interferences from $$^{3}$$H and $$^{85}$$Kr; $$^{85}$$Kr was continuously measured by combination of two kinds of detectors to cover very wide range of the concentration; and $$^{129}$$I was collected by a charcoal filter and a charcoal cartridge in series with a relatively high collecting performance.

Oral presentation

Influence of the radioactivities released from the accident of Fukushima Daiichi NPP on the monitoring of environmental $$gamma$$-ray dose rate around TRP

Mizutani, Tomoko; Onuma, Toshimitsu; Morisawa, Masato; Watanabe, Hajime*; Sugai, Masamitsu*; Nakada, Akira; Sumiya, Shuichi

no journal, , 

no abstracts in English

Oral presentation

Development and utilization of Web-based open system for CT dose calculator, WAZA-ARIv2

Koba, Yusuke*; Nakada, Yoshihiro*; Matsumoto, Shinnosuke*; Akahane, Keiichi*; Ono, Koji*; Sato, Kaoru; Takahashi, Fumiaki; Endo, Akira; Shimada, Yoshiya*; Kai, Michiaki*

no journal, , 

While CT scan is useful for diagnosis, exposure dose derived from CT scan is relatively high. Therefore, it is important to manage patient doses and to prevent the excess exposures in young patients. JAEA developed the CT dose calculator, WAZA-ARIv2 under the collaboration research project with the National Institute of Radiological Sciences and the Oita University of Nursing and Health Sciences. In WAZA-ARIv2, users can accurately calculate exposure doses through the browser under consideration of patients information about sexes, ages (0y, 1y, 5y, 10y, 15y and adult) and fatness (small, large and extra-large body sizes). The functions of registration and database compilation of CT scan conditions and patient doses are newly added to a WAZA-ARIv2. Users can compare the distribution of patient doses in Japan with those in user's medical institution. Therefore, it will be expected that WAZA-ARIv2 can contribute the management and optimization of patients doses due to CT scan.

Oral presentation

The Effect of leakage rates on the difference of states wearing respirator

Nakayama, Naoto; Yatsuda, Kazumi; Hamazaki, Masaaki; Usui, Toshihide; Nakada, Akira

no journal, , 

no abstracts in English

Oral presentation

Characterization of removal factor of materials used for smear method on house material

Hamazaki, Masaaki; Mori, Airi; Abe, Haruka; Goibuchi, Shota; Iwasa, Atsutoshi; Ishida, Keiichi; Usui, Toshihide; Eguchi, Kazutoshi; Nakada, Akira

no journal, , 

no abstracts in English

Oral presentation

Spectroscopic study of uranium materials for understanding chemical degradation of fuel debris

Kumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Akiyama, Daisuke*; Watanabe, Masayuki; Sasaki, Takayuki*; Sato, Nobuaki*; Kirishima, Akira*

no journal, , 

Since uranium (U) can take numerous chemical states depending on conditions to which it is exposed, the chemical behavior of fuel components is needed for fuel debris treatment generated by Fukushima Daiichi NPS accident. Therefore, understanding on the chemistry of the U materials is essential to estimate these materials' stabilities. One of the important chemical dynamics of uranium is oxidative dissolution of U(IV) materials. It is well known that under the action of ionizing radiation U(IV) oxide matrix of nuclear fuel is gradually oxidized to U(VI) that is fairly water-soluble as uranyl ion. Then, the dissolution of the matrix and the release of radionuclides take place by contact with water. Such chemical degradation may occur for the fuel debris in the Fukushima Daiichi NPS. Hence, we have been investigating the chemical stability of U materials which are anticipated to be included in the fuel debris. As a first step of the investigation, we applied spectroscopic analysis, namely Raman scattering and fluorescence microscopic spectroscopies and Fe-57 M$"o$ssbauer spectroscopy for chemical characterization of a pyrochemical product prepared from U(IV) oxide and stainless steel. We have employed these spectroscopic techniques since they are applicable for surface analysis. This is a specific advantage for the investigation of chemical degradation of solid U materials.

Oral presentation

Research on the stability of fuel debris consisting of oxides and alloys, 2; Analysis of chemical state of U-Fe-Cr-Ni oxide by spectroscopic method

Watanabe, Masayuki; Kumagai, Yuta; Kusaka, Ryoji; Yomogida, Takumi; Nakada, Masami; Kirishima, Akira*; Akiyama, Daisuke*; Sato, Nobuaki*; Sasaki, Takayuki*

no journal, , 

In this presentation, we will report the results related with the chemical states on the surface of the simulated fuel debris which is synthesized from uranium and stainless steel and single component of uranium oxides are identified by fluorescence microscopy, raman microscopy and M$"o$ssbauer spectroscopy.

Oral presentation

Uranium leaching from simulated fuel debris prepared from UO$$_{2}$$ and stainless steel

Kumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Kirishima, Akira*; Akiyama, Daisuke*; Sato, Nobuaki*; Sasaki, Takayuki*; Kobayashi, Taishi*

no journal, , 

Fuel debris generated due to nuclear severe accidents is expected to contain a wide variety of uranium compounds. In this project, we have investigated chemical stability of simulated fuel debris containing elements from stainless steel (Fe, Cr, and Ni) against exposure to water. The simulated debris was prepared from the powders of UO$$_{2}$$ and SUS304 by heating the mixed powder at 1200 $$^{circ}$$C for 1 h under continuous gas flow of 2% O$$_{2}$$ in Ar. The produced powder was characterized by XRD, SEM-EDX, Raman micro-spectroscopy, and M$"o$ssbauer spectroscopy. The series of characterization revealed that the simulated debris comprised U(Fe,Cr)O$$_{4}$$, U$$_{3}$$O$$_{8}$$, and Fe(III) oxides. Then, the simulated debris was exposed to pure water for 30 days. The same leaching test of U$$_{3}$$O$$_{8}$$ was performed for comparison. The chemical analysis of leached metals demonstrated that the U elution from the simulated debris was significantly lower than that from U$$_{3}$$O$$_{8}$$. In addition, Fe, Cr, and Ni were under quantitation limit as well. The Raman spectra showed that the exposure to water induced insignificant change in the spectra of the simulated debris, while the Raman band structure of U$$_{3}$$O$$_{8}$$ seemed to become slightly unclear after 30 days immersion.

Oral presentation

Research on the stability of fuel debris consisting of oxides and alloys, 4; Spectroscopic analysis for evaluation of the stability of simulated fuel debris in water

Kumagai, Yuta; Watanabe, Masayuki; Kusaka, Ryoji; Nakada, Masami; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Sasaki, Takayuki*

no journal, , 

Fuel debris generated in the accident at 1F NPS has been exposed to coolant water and the condition will change once the retrieval operation starts. In this situation, long-term chemical degradation is implied from previous studies on spent nuclear fuel. In this study, we have investigated chemical stability of simulated fuel debris containing elements from stainless steel (Fe, Cr, and Ni) against exposure to water. The simulated debris was prepared from the powders of UO$$_{2}$$ and SUS304 by heating the mixed powder at 1200 or 1600 $$^{circ}$$C for 1 h under continuous gas flow of 2% O$$_{2}$$ in Ar. The simulated debris was exposed to pure water for 30 days. The chemical analysis of leached metals demonstrated that the U elution from the simulated debris was significantly lower than that from U$$_{3}$$O$$_{8}$$. In addition, Fe, Cr, and Ni were under quantitation limit. The Raman spectra showed that the exposure to water induced insignificant change in the spectra of the simulated debris.

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