Spatial distribution of radionuclides in seabed sediments off Ibaraki coast after the Fukushima Daiichi Nuclear Power Plant accident

Nagaoka, Mika; Yokoyama, Hiroya; Fujita, Hiroki; Nakano, Masanao; Watanabe, Hitoshi; Sumiya, Shuichi

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1305 - 1308, 2015/02

https://doi.org/10.1007/s10967-014-3633-9

Various kinds of radionuclides were released into the atmosphere and the sea from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. (TEPCO) by the accident and then reached around our laboratories. Therefore the accident influence on our environment was investigated to measure the concentrations of cesium-134 (Cs), cesium-137 Cs, strontium-90 (Sr) and plutonium isotopes in seabed sediments. The values for Cs ranged from 6.1 to 300 Bq/kg (dry wt) and the ratio of Cs /Cs ranged from 0.48 to 0.77. The highest point of Cs concentration was observed at the northernmost station near Kitaibaraki City and the concentration was similar to report by MEXT.

Spatial distribution of radionuclides in seabed sediments off the Ibaraki coast

Nagaoka, Mika; Yokoyama, Hiroya; Fujita, Hiroki; Nakano, Masanao; Watanabe, Hitoshi; Sumiya, Shuichi

KEK Proceedings 2014-7, p.194 - 200, 2014/11

no abstracts in English

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2012

Sumiya, Shuichi; Watanabe, Hitoshi; Miyagawa, Naoto; Nakano, Masanao; Fujita, Hiroki; Kono, Takahiko; Inoue, Kazumi; Yoshii, Hideki; Otani, Kazunori*; Hiyama, Yoshinori*; et al.

JAEA-Review 2013-041, 115 Pages, 2014/01

JAEA-Review-2013-041.pdf:19.01MB

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 bylaw 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 2012, from 1st April 2012 to 31st March 2013. In this period, the concentrations and the quantities of the radioactivity in 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.

Examination on the long-term practicability of a Doppler Lidar; Data missing rate and comparison of wind direction and speed with the propeller type

Nakano, Masanao; Watanabe, Hitoshi; Sumiya, Shuichi

JAEA-Testing 2013-003, 29 Pages, 2013/11

JAEA-Testing-2013-003.pdf:11.89MB

Since the remote sensing technique for the meteorological observation has been developing these years, the Doppler Lidar is available in the commercial market. Although some investigation organization carried out the examination on the method and application of Doppler Lidars and had generally good results, the duration of the examination was limited in a short period. So it is unknown that the Doppler Lidar can be applicable to the long-term meteorological observation in the nuclear facilities to assess the public dose around nuclear facilities. In order to examine the long-term performance requested by the Japanese guideline for meteorological observation (i.e., the annual and the sequential 30-days missing rate should be less than 10% and 30%, respectively.) and the consistency with the data measured by conventional type, the wind direction and speed was measured by the Doppler Lidar (Windcube WLS7 made by Leosphere Co Ltd.) for one year, then compared with those by the propeller type installed at the top of the meteorological observation tower. As the result, the missing rate of the Doppler Lidar was satisfied with the guideline at the height less than 180 m, and the data at 68 m above the ground level (100 m above sea level) had a good relationship with the propeller data. From this fact, the Doppler Lidar used in this examination is considered to have a practicability for the dose assessment of the public.

The Result of radionuclide concentrations in fallout around Tokai Reprocessing Plant after Fukushima Daiichi Nuclear Power Plant accident

Nagaoka, Mika; Fujita, Hiroki; Nakano, Masanao; Watanabe, Hitoshi; Sumiya, Shuichi

Hoken Butsuri, 48(2), p.104 - 113, 2013/06

https://doi.org/10.5453/jhps.48.104

Monthly deposition samples were collected in the NCL which is located at about 115km south of the Fukushima Daiichi NPP, and the radioactive nuclides were analyzed. Although radionuclides such as I (T=8.02 days), Te-Te (T=33.6 days) and Te-I (T=3.2 days) with Cs and Cs were observed by spectrometry at the early time of the Fukushima Daiichi NPP accident, only Cs and Cs were detected as of September 2012. The annual deposition of Cs and Cs were about 19,000 and 17,000 Bq/m, respectively in March 2011 - February 2012 after the accident. Moreover, Sr was detected in some samples. Monthly Sr deposition in March 2011 was 5.1 Bq/m month and then decreased after that. On the other hand, Pu concentration was the same level with the concentration before the accident.

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

Nagaoka, Mika; Nakano, Masanao; Fujita, Hiroki; Watanabe, Hitoshi; Sumiya, Shuichi

Dai-55-Kai Kankyo Hoshano Chosa Kenkyu Seika Rombun Shorokushu (Heisei-23-Nendo), p.7 - 8, 2013/03

no abstracts in English

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2010

Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Kono, Takahiko; Hiyama, Yoshinori; Yoshii, Hideki*; Kikuchi, Masaaki*; Otani, Kazunori*; Goto, Ichiro*

JAEA-Review 2012-006, 114 Pages, 2012/03

JAEA-Review-2012-006.pdf:3.36MB

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 2010, from 1st April 2010 to 31st March 2011. In this period, the concentrations and the quantities of the radioactivity in 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.

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.

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2009

Sumiya, Shuichi; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Kono, Takahiko; Hiyama, Yoshinori; Yoshii, Hideki*; Fujii, Jun*; Kikuchi, Masaaki*; et al.

JAEA-Review 2010-072, 115 Pages, 2011/02

JAEA-Review-2010-072.pdf:2.1MB

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 2009, from 1st April 2009 to 31st March 2010. In this period, the concentrations and the quantities of the radioactivity in 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.

Rapid analysis method of Sr and Sr in effluent with a liquid scintillation counter

Nakano, Masanao; Hiyama, Yoshinori; Watanabe, Hitoshi; Sumiya, Shuichi

Radioisotopes, 59(5), p.319 - 328, 2010/05

https://doi.org/10.3769/radioisotopes.59.319

The rapid analysis method of Sr and Sr in effluent has been investigated by a liquid scintillation counter, which could distinguish the difference of beta energy. Analyzed the imitation effluent samples including interference radionuclides such as Mn, Co, Ru, Cs, the good accuracy, precision and chemical recovery were obtained in the analyses. It took only 3 or 4 days to analyze them by this method, though it took a few weeks by the conventional methods. These facts made it sure that this method was worth enough for the analysis of Sr and Sr in effluent.