Tokyo Nuclear Services Co.

Taitō-ku, Japan

Tokyo Nuclear Services Co.

Taitō-ku, Japan
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Fuma S.,Japan National Institute of Radiological Sciences | Ihara S.,Hokkaido University of Education | Takahashi H.,Tokyo Nuclear Services Co. | Inaba O.,Minamisoma City Museum | And 7 more authors.
Journal of Environmental Radioactivity | Year: 2017

To characterise the radioactive contamination of terrestrial and freshwater wildlife caused by the Fukushima Dai-ichi Nuclear Power Plant accident, biological samples, namely, fungi, mosses, plants, amphibians, reptiles, insects, molluscs, and earthworms, were collected mainly from the forests of the exclusion zone in the Fukushima Prefecture from 2011 to 2012. Caesium-134 and 137Cs were detected by gamma spectrometry in almost all the samples. Fungi, ferns, and mosses accumulated high amounts of radiocaesium, as they did in Chernobyl, with 134Cs + 137Cs activity concentrations of 104–106 Bq kg−1 fresh mass (FM). Earthworms, amphibians, and the soft tissue of the garden snail Acusta despecta sieboldiana, also had levels as high as 104–105 Bq kg−1 FM of 134Cs + 137Cs. Most of the estimated total (internal + external) dose rates to herbaceous plants, amphibians, insects, and earthworms were below the corresponding derived consideration reference levels (DCRLs) recommended by the ICRP. This suggests that, in most cases, there was little chance of deleterious effects of ionising radiation on these organisms in the exclusion zone for the first year after the accident, though the dose rates were underestimated mainly due to the lack of consideration of short-lived radionuclides. © 2017 Elsevier Ltd


Fuma S.,Japan National Institute of Radiological Sciences | Kubota Y.,Japan National Institute of Radiological Sciences | Ihara S.,Hokkaido University of Education | Takahashi H.,Tokyo Nuclear Services Co. | And 4 more authors.
Journal of Environmental Radioactivity | Year: 2016

Analysis of radioactivity data obtained under the food monitoring campaign in Japan indicates that elevated 134Cs+137Cs activity concentrations in wild boar meat remained constant or slowly decreased in Fukushima and surrounding prefectures from 2011 to 2015. The activity concentrations in some samples are still over the regulatory limit of 100 Bq kg−1 fresh weight, even in 2015. Activity concentrations of 137Cs in muscle of wild boars we captured in 2011 were higher than those in kidney, liver, spleen, heart and lung. A food processing retention factor, Fr, was 0.5 or 0.6 for 137Cs when the wild boar meat was boiled, suggesting that a parboiling process is effective for reduction of radiocaesium intake from wild boar meat. © 2016 Elsevier Ltd


PubMed | Tokyo Nuclear Services Co., Japan National Institute of Radiological Sciences, Hokkaido University of Education and National Institutes for Quantum and Radiological Science and Technology
Type: | Journal: Journal of environmental radioactivity | Year: 2016

Analysis of radioactivity data obtained under the food monitoring campaign in Japan indicates that elevated


PubMed | Japan National Institute of Radiological Sciences, Azabu University, Fukushima Wildlife Workshop, Tokyo Nuclear Services Co. and 2 more.
Type: | Journal: Journal of environmental radioactivity | Year: 2015

The radiological risks to the Tohoku hynobiid salamanders (class Amphibia), Hynobius lichenatus due to the Fukushima Dai-ichi Nuclear Power Plant accident were assessed in Fukushima Prefecture, including evacuation areas. Aquatic egg clutches (n = 1 for each sampling date and site; n = 4 in total), overwintering larvae (n = 1-5 for each sampling date and site; n = 17 in total), and terrestrial juveniles or adults (n = 1 or 3 for each sampling date and site; n = 12 in total) of H. lichenatus were collected from the end of April 2011 to April 2013. Environmental media such as litter (n = 1-5 for each sampling date and site; n = 30 in total), soil (n = 1-8 for each sampling date and site; n = 31 in total), water (n = 1 for each sampling date and site; n = 17 in total), and sediment (n = 1 for each sampling date and site; n = 17 in total) were also collected. Activity concentrations of (134)Cs + (137)Cs were 1.9-2800, 0.13-320, and 0.51-220 kBq (dry kg) (-1) in the litter, soil, and sediment samples, respectively, and were 0.31-220 and <0.29-40 kBq (wet kg)(-1) in the adult and larval salamanders, respectively. External and internal absorbed dose rates to H. lichenatus were calculated from these activity concentration data, using the ERICA Assessment Tool methodology. External dose rates were also measured in situ with glass dosimeters. There was agreement within a factor of 2 between the calculated and measured external dose rates. In the most severely contaminated habitat of this salamander, a northern part of Abukuma Mountains, the highest total dose rates were estimated to be 50 and 15 Gy h(-1) for the adults and overwintering larvae, respectively. Growth and survival of H. lichenatus was not affected at a dose rate of up to 490 Gy h(-1) in the previous laboratory chronic gamma-irradiation experiment, and thus growth and survival of this salamander would not be affected, even in the most severely contaminated habitat in Fukushima Prefecture. However, further studies of the adult salamanders may be required in order to examine whether the most severe radioactive contamination has any effects on sensitive endpoints, since the estimated highest dose rate to the adults exceeded some of the guidance dose rates proposed by various organisations and programmes for the protection of amphibians, which range from 4 to 400 Gy h(-1). Conversely, at one site in Nakadori, a moderately contaminated region in Fukushima Prefecture, the dose rate to the adult salamanders in spring of 2012 was estimated to be 0.2 Gy h(-1). Estimated dose rates to the overwintering larvae in spring of 2012 were 1 and 0.2 Gy h(-1) at one site in Nakadori, and in Aizu, a less contaminated region in Fukushima Prefecture, respectively. These results suggest that there is a low risk that H. lichenatus will be affected by radioactive contamination in these districts, though further studies on dose rate estimation are required for definitive risk characterisation.


Kubota Y.,Japan National Institute of Radiological Sciences | Takahashi H.,Tokyo Nuclear Services Co. | Watanabe Y.,Japan National Institute of Radiological Sciences | Fuma S.,Japan National Institute of Radiological Sciences | And 9 more authors.
Journal of Environmental Radioactivity | Year: 2015

The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium (134Cs and 137Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (<10% of the total absorbed dose rate). The average total absorbed dose rate to wild rodents inhabiting the sampling area was estimated to be approximately 52 μGyh-1 (1.2 mGyd-1), even 3 years after the accident. This dose rate exceeds 0.1-1mGyd-1 derived consideration reference level for Reference rat proposed by the International Commission on Radiological Protection (ICRP). © 2015 Elsevier Ltd.


PubMed | Japan Forestry and Forest Products Research Institute, Tokyo Nuclear Services Co., Japan National Institute of Radiological Sciences, Japan Wildlife Research Center and Japan NUS Co.
Type: | Journal: Journal of environmental radioactivity | Year: 2015

The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium ((134)Cs and (137)Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (<10% of the total absorbed dose rate). The average total absorbed dose rate to wild rodents inhabiting the sampling area was estimated to be approximately 52 Gy h(-1) (1.2 mGy d(-1)), even 3 years after the accident. This dose rate exceeds 0.1-1 mGy d(-1) derived consideration reference level for Reference rat proposed by the International Commission on Radiological Protection (ICRP).


Tagami K.,Japan National Institute of Radiological Sciences | Uchida S.,Japan National Institute of Radiological Sciences | Ishii N.,Japan National Institute of Radiological Sciences | Kagiya S.,Tokyo Nuclear Services Co.
Journal of Environmental Radioactivity | Year: 2012

An accident occurred at the Fukushima Dai-ichi Nuclear Power Plant in March 2011 at which time large amounts of radionuclides were released into the atmosphere and the sea. In early May 2011, it was found that newly emerged tea (Camellia sinensis) leaves contained radiocesium, both 134Cs and 137Cs in some areas more than 300 km away from the Fukushima plant. To understand the mechanisms of radiocesium transfer to newly emerged tissues (shoots, leaves and fruits) of other plants in the future, radiocesium concentrations in newly emerged leaves of 14 plant species collected from the sampling areas in and near National Institute of Radiological Sciences in Chiba, Japan. The studied plant types were: (1) herbaceous plants, (2) woody plants with no old leaves at the time of the March accident, and (3) woody plants with old leaves out before the accident. About 40-50 d after the start of the accident, newly emerged leaves from woody plant with old leaves tended to show higher values than other woody or herbaceous plants. Concentrations of radiocesium in newly emerged tissues of trees decreased with time, but they did not decrease to the level of herbaceous plants. The type of the plant and presence of old leaves at the time of the heavy deposition period affected the radiocesium concentrations in newly emerged tissues. © 2011 Elsevier Ltd.


Ishii N.,Japan National Institute of Radiological Sciences | Koiso H.,Tokyo Nuclear Services Co. | Takeda H.,Japan National Institute of Radiological Sciences | Uchida S.,Japan National Institute of Radiological Sciences
Journal of Nuclear Science and Technology | Year: 2010

The partitioning ratios of 14C in solid, liquid, and gas phases were determined by batch sorption tests using 97 paddy soil samples. Each of the soil samples was suspended in deionized water containing [1, 2- 14C] sodium acetate and shake-incubated for 7 days. More than 65% of the spiked 14C was released into the air, approximately 30% was partitioned into the solid phase, and the 14C remaining in the liquid phase was only a few percent. These results suggested that if the 14C incorporated into acetate migrated from a TRU repository site to paddy fields, most of the 14C would be released into the air and the rest would be partitioned into the soil phase. It is likely that microorganisms in the soils are responsible for these partitioning ratios because about 97% of the spiked 14C remained in the liquid phase in the microorganism-depleted sample. © Atomic Energy Society of Japan.


Takata H.,Japan National Institute of Radiological Sciences | Takata H.,Marine Ecology Research Institute | Aono T.,Japan National Institute of Radiological Sciences | Zheng J.,Japan National Institute of Radiological Sciences | And 3 more authors.
Analytical Methods | Year: 2013

A highly sensitive and simple analytical method is applied to the determination of Cs in estuarine and coastal waters. This analytical method combines adsorption of Cs on ammonium 12-molybdophosphate (AMP) and an ion exchange resin column, followed by subsequent ICPMS measurement. Significantly, the method requires a relatively small amount of sample volume (minimum volume: 20 mL) for the analysis by the selection of AMP with a low Cs impurity (0.02 ng-Cs mg-1-AMP). The method has a detection limit of 1.0 ng L -1 and a limit of quantification of 3.3 ng L-1 based on replicate analyses of purified water samples. A sample storage strategy is also investigated: no time dependent changes are found in the concentrations for acidified samples (pH 1.0-1.5) used immediately (storage: 0 day) to those stored for two months in a dark place at room temperature (4-20 °C) or in a freezer (ca. -20 °C). Respective Cs concentrations of 95.8 ± 0.9, 202.8 ± 3.6 and 197.0 ± 1.9 ng L-1 are obtained in estuarine water (SLEW-3), coastal seawater (CASS-4) and seawater (NASS-5) certified reference materials for heavy metals. In an application of the method to determination of Cs in estuarine and coastal regions of Japan, the obtained Cs concentrations vary from 11.2 to 306.4 ng L-1 at a salinity range of 0.1 to 33.6. This journal is © 2013 The Royal Society of Chemistry.


Kawamura K.,Japan National Institute of Radiological Sciences | Yamasaki T.,Japan National Institute of Radiological Sciences | Konno F.,Japan National Institute of Radiological Sciences | Yui J.,Japan National Institute of Radiological Sciences | And 8 more authors.
Molecular Imaging and Biology | Year: 2011

Purpose: GF120918 has a high inhibitory effect on P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). We developed [11C]GF120918 as a positron emission tomography (PET) probe to assess if dual modulation of P-gp and BCRP is useful to evaluate brain penetration. Procedures: PET studies using [11C]GF120918 were conducted on P-gp and/or Bcrp knockout mice as well as wild-type mice. Results: In PET studies, the AUCbrain [0-60 min] and K 1 value in P-gp/Bcrp knockout mice were nine- and 26-fold higher than that in wild-type mice, respectively. These results suggest that brain penetration of [11C]GF120918 is related to modulation of P-gp and BCRP and is limited by two transporters working together. Conclusions: PET using [11C]GF120918 may be useful for evaluating the function of P-gp and BCRP. PET using P-gp/Bcrp knockout mice may be an effective method to understand the overall contributions the functions of P-gp and BCRP. © 2010 Academy of Molecular Imaging and Society for Molecular Imaging.

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