Estimation of Effect of Radiation Dose Reduction for Internal Exposure by Food Regulations under the Current Criteria for Radionuclides in Foodstuff in Japan Using Monitoring Results

This study examined the effect of food regulations under the current criteria (e.g., 100 Bq/kg for general foods) established approximately a year after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Foods are monitored to ensure that foods exceeding the standard limit are not distributed; ~300,000 examinations per year have been performed especially since FY2014. This study comprehensively estimated the internal exposure dose resulting from the ingestion of foods containing radioactive cesium using the accumulated monitoring results. Committed effective dose was conservatively calculated as the product of the radioactive concentration randomly sampled from test results, food intake, and dose coefficient. The median, 95th, and 99th percentile of the dose were 0.0479, 0.207, and 10.6 mSv/y, respectively, in the estimation with all test results (without regulation), and 0.0430, 0.0790, and 0.233 mSv/y, respectively, in the estimation with results within the standard limits (with regulation) in FY2012. In FY2016, the dose with and without regulation were similar, except for high percentile, and those doses were significantly smaller than 1 mSv/y, which was adopted as the basis for the current criteria. The food regulation measures implemented in Japan after the FDNPP accident have been beneficial, and food safety against radionuclides has been ensured.

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Dissolution, Mechanical Properties, and Thermal Stability of Microparticles Containing Radioactive Cesium on Plant Litter Derived from the Fukushima Daiichi Nuclear Power Plant Accident, and Soil Decontamination Trials

10.5194/egusphere-egu21-2976 ◽

2021 ◽

Author(s):

Ichiro Tanaka ◽

Atsushi Yamaguchi ◽

Kenji Kikuchi ◽

Nobuo Niimura ◽

Yume Saeki ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Stability ◽

Power Plant ◽

Nuclear Power Plant ◽

Nuclear Power ◽

Plant Litter ◽

Radioactive Cesium ◽

Soil Decontamination ◽

Fdnpp Accident ◽

Fukushima Daiichi

The radioactive cesium (134Cs and 137Cs), which originated from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, has remained in the soil and on plants as water-insoluble microparticles (termed as CsMPs) to some extent, and maintained relatively high radioactivity levels in the district. However, it has been reported that the radioactive Cs has been absorbed by plants. To interpret this phenomenon, the authors investigated CsMPs to determine if they become soluble during filtration and dialysis experiments. Moreover, other physical properties, such as mechanical properties and thermal stability, were observed during the course of the relevant experiments. These properties can be obtained by using carbonized charcoal litter with CsMPs. And simple and economic decontamination trials of the soil were performed by sieving after drying and roughly crushing.

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Dissolution, Mechanical Properties, and Thermal Stability of Microparticles Containing Radioactive Cesium on Plant Litter Derived from the Fukushima Daiichi Nuclear Power Plant Accident

Radiology and Medical Diagnostic Imaging ◽

10.31487/j.rdi.2020.04.04 ◽

2020 ◽

pp. 1-8

Author(s):

Ichiro Tanaka ◽

Atsushi Yamaguchi ◽

Kenji Kikuchi ◽

Masakazu Komatsuzaki ◽

Ichiro Tanaka ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Stability ◽

Power Plant ◽

Nuclear Power Plant ◽

Nuclear Power ◽

Plant Litter ◽

Radioactive Cesium ◽

Fdnpp Accident ◽

Fukushima Daiichi ◽

Thermal Stability Of

Most of the radioactive cesium (134Cs and 137Cs), which originated from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, has remained in the soil and on plants as water-insoluble microparticles (termed as CsMPs) and maintained relatively high radioactivity levels in the district. However, it has been reported that the radioactive Cs has been absorbed by plants. To interpret this phenomenon, the authors investigated CsMPs to determine if they become soluble during filtration and dialysis experiments. Moreover, other physical properties, such as mechanical properties and thermal stability, were observed during the course of the relevant experiments. These properties can be obtained by using carbonized charcoal litter with CsMPs.

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Study of soil particles containing radioactive cesium in paddy field soil using an energy-dispersive X-ray spectroscopy and autoradiogram method

International Journal of PIXE ◽

10.1142/s0129083519500050 ◽

2018 ◽

Vol 28 (01n02) ◽

pp. 29-33

Author(s):

Tohru Ohnuma ◽

Keizo Ishii

Keyword(s):

Nuclear Power ◽

Energy Dispersive ◽

Radioactive Cesium ◽

Restricted Area ◽

Soil Particles ◽

X Ray ◽

Fdnpp Accident ◽

Paddy Field Soil ◽

Fukushima Daiichi ◽

Scanning Electron

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011 caused the widespread contamination of Fukushima Prefecture by radioactive cesium. The cesium radioisotopes are considered to have remained in the soil for seven years. We investigated this situation by analyzing soil from paddy fields in the area. We investigated the structure of soil particles using scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS) and autoradiogram (ARG). We estimated the percentage of clay in the soil based on its composition, and then obtained the radioactivity of the cesium radioisotopes for each soil particle size as a function of penetration. The cesium radioisotopes were exponentially distributed in soil containing a large proportion of clay. Hence, we confirmed that the quantity of clay in the soil is a very important factor with respect to the possibility of the resumption of agriculture in the restricted area.

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The Knowledge and Awareness for Radiocesium Food Monitoring after the Fukushima Daiichi Nuclear Accident in Nihonmatsu City, Fukushima Prefecture

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph15102289 ◽

2018 ◽

Vol 15 (10) ◽

pp. 2289 ◽

Cited By ~ 3

Author(s):

Nobuaki Kunii ◽

Maya Fujimura ◽

Yukako Komasa ◽

Akiko Kitamura ◽

Hitoshi Sato ◽

...

Keyword(s):

Nuclear Power ◽

Internal Exposure ◽

Wild Plants ◽

Fukushima Prefecture ◽

Edible Wild Plants ◽

Increased Risk ◽

Fdnpp Accident ◽

Food Monitoring ◽

Fukushima Daiichi ◽

The Government

On 11 March 2011, Japan experienced a massive earthquake and tsunami that triggered the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, resulting in the release of large amounts of cesium-134 and -137 into the atmosphere. In addition to the food radioactivity control in the markets throughout the country, radiocesium concentrations in locally grown foods were voluntarily inspected and the results were shown to the residents by the local government to raise their awareness of the internal radiation contamination risk from low knowledge in Nihonmatsu City, Fukushima Prefecture. In this longitudinal study, local food products for in-home consumption were evaluated by seven different food radioactivity measuring devices in Nihonmatsu City from 2011–2017. Radiocesium was detected in local foods in Nihonmatsu City even six years after the FDNPP accident. The highest number of products tested was in 2012, with the number steadily decreasing thereafter. Most foods had contamination levels that were within the provisional regulation limits. As edible wild plants and mushrooms continue to possess high radiocesium concentrations, new trends in radioactivity in foods like seeds were discovered. This study highlights that the increased risk of radiation exposure could possibly be due to declining radiation awareness among citizens and food distributors. We recommend the continuation of food monitoring procedures at various points in the food processing line under the responsibility of the government to raise awareness for the reduction of future risks of internal exposure.

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Monitoring of Tritium Internal Exposure Doses of Heavy-Water Reactor Workers in Third Qinshan Nuclear Power Plant

Dose-Response ◽

10.1177/1559325819890498 ◽

2019 ◽

Vol 17 (4) ◽

pp. 155932581989049

Author(s):

Kong-Zhao Wang ◽

Lei Sun ◽

Kou-Hong Xiong ◽

Wei-Bo Chen ◽

You-You Wang ◽

...

Keyword(s):

Power Plant ◽

Nuclear Power Plant ◽

Nuclear Power ◽

Health And Safety ◽

Exposure Dose ◽

Internal Exposure ◽

Plant Management ◽

Radiation Doses ◽

Collective Dose ◽

The Third

To analyze the tritium internal exposure dose of workers in the Third Qinshan Nuclear Power Plant over the past 15 years. Urine samples provided by workers are tested directly to analyze the tritium concentrations and estimate internal exposure dose. Since 2004, an average of approximately 1600 workers have been monitored annually, with an average annual monitoring frequency of approximately 11 000. Since 2004, the average annual collective dose of tritium internal exposure was 149.62 person·mSv, accounting for 19.07% of the total annual collective dose. A total of 18 workers’ annual individual internal tritium radiation doses exceeded 2 mSv, of which 5 workers’ internal tritium radiation doses in a single intake exceeded 2 mSv. The occupational population with the largest total internal tritium radiation doses consists of maintenance personnel, fuel operators, and radiation protection personnel, whose collective doses of internal exposure account for 75.51% of the total collective doses within the plant. Over 15 years of operation, the internal tritium radiation doses of workers in the Third Qinshan Nuclear Power Plant have been strictly controlled within the national regulatory limit and power plant management target, ensuring the health and safety of the workers.

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Analysis of radioactive cesium-enriched particles and measurement of their distribution in marine sediment near Fukushima Daiichi nuclear power plant

Journal of Nuclear Science and Technology ◽

10.1080/00223131.2021.1879688 ◽

2021 ◽

Vol 58 (4) ◽

pp. 482-492

Author(s):

Seiki Ohnishi ◽

Blair Thornton ◽

Toshikazu Koike ◽

Naoteru Odano ◽

Mitsufumi Asami ◽

...

Keyword(s):

Power Plant ◽

Nuclear Power Plant ◽

Marine Sediment ◽

Nuclear Power ◽

Radioactive Cesium ◽

Fukushima Daiichi

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Transition of Radioactive Cesium Deposition in Reproductive Organs of Free-Roaming Cats in Namie Town, Fukushima

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18041772 ◽

2021 ◽

Vol 18 (4) ◽

pp. 1772

Author(s):

Yohei Fujishima ◽

Yasushi Kino ◽

Takumi Ono ◽

Valerie Swee Ting Goh ◽

Akifumi Nakata ◽

...

Keyword(s):

Reproductive Organs ◽

137Cs Activity ◽

Control Group ◽

Radioactive Cesium ◽

Felis Silvestris Catus ◽

Dose Rates ◽

Fdnpp Accident ◽

Radioactivity Monitoring ◽

Adult Cats ◽

Ambient Dose

We investigated the internal contamination by radioactive cesium associated with the FDNPP accident, in the testes or uterus and ovaries of free-roaming cats (Felis silvestris catus), which were protected by volunteers in the Namie Town, Fukushima. A total of 253 samples (145 testes and 108 uterus and ovaries) obtained from adult cats and 15 fetuses from 3 pregnant female cats were measured. Free-roaming cats in Namie Town had a higher level of radioactive contamination in comparison to the control group in Tokyo, as the 134Cs + 137Cs activity concentration ranged from not detectable to 37,882 Bq kg−1 in adult cats. Furthermore, the radioactivity in the fetuses was almost comparable to those in their mother’s uterus and ovaries. The radioactivity was also different between several cats protected in the same location, and there was no significant correlation with ambient dose-rates and activity concentrations in soil. Moreover, radioactive cesium levels in cats decreased with each year. Therefore, it is likely that decontamination work in Namie Town and its surroundings could affect radioactive cesium accumulation, and thus possibly reduce the internal radiation exposure of wildlife living in contaminated areas. It is hence necessary to continue radioactivity monitoring efforts for the residents living in Namie Town.

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The moral construction of worry about radiation exposure: Emotion, knowledge, and tests

Discourse & Society ◽

10.1177/0957926517721081 ◽

2017 ◽

Vol 28 (6) ◽

pp. 635-656 ◽

Cited By ~ 3

Author(s):

Aug Nishizaka

Keyword(s):

Radiation Exposure ◽

Conversation Analysis ◽

Internal Exposure ◽

Test Results ◽

Communication Tool ◽

Work Related ◽

Video Recordings ◽

Moral Construction ◽

Fukushima Disaster ◽

Do So

In the analysis of video recordings of the interactions between a doctor and the examinees following internal radiation exposure tests at a hospital in Fukushima Prefecture, I explore how the participants address one of the most serious consequences of the Fukushima disaster, that is, their concerns about radioactive materials. To do so, this study employs conversation analysis. The doctor’s presentation of the test results provides the examinees with a place to express relief and also makes relevant the justification work related to the expression of relief. In conclusion, I consider how the internal exposure tests also function as a communication tool in the context in which residents from affected areas face potential difficulties in expressing their worry about radiation.

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