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For the purpose of determining a surface deposition density on soil for radio-cesiums, a CdZnTe (CZT) semiconductor detector whose crystal has dimensions of 1 cm cubic was applied to the in situ environmental radioactivity measurement in deeply contaminated areas in Fukushima region. Even in high–dose rate areas where pulse height spectra weren’t able to be properly obtained by the conventional high-purity Ge (Hp-Ge) semiconductor detector, proper pulse height spectra were obtained by the CZT detector with certain accuracy. Results of deposition density on soil for Cs and Cs derived from net peak areas by the CZT detector seemed consistent, comparing with those measured by the Japanese government. Air kerma rates were estimated by the same pulse height spectra for determining surface deposition density on soil for radio-cesiums. Estimated results showed almost the same values as obtained by the NaI(Tl) scintillation survey meter. The results indicate that the CZT detector can be applied to rapid and simple in situ gamma ray radioactivity measurement in higher–dose rate areas whose dose rates exceed several tenth μSv h. The study also strongly supports that the CZT detector is one promising candidate for the detector to be used for checking the effect of decontamination works and for long-term monitoring in heavily contaminated areas.

After the TEPCO Fukushima DAIICHI NPP accident, IAEA and ICRP advised accelerating the decontamination work to clean up the living environment of the areas where additional annual radiation exposure doses are beyond 1 mSv per year (i.e., 1 mSv/y) and to diminish radiation worries. However, the advice was not recognized well because it did not contain clearly understandable numerical data. In the present work, the ambient radiation dose rates in the Nakadori district have been investigated to clarify that the doses are lower than 1 mSv/y in the major part where the decontamination was completed. A part of the district and three municipalities in the special decontamination area have doses of 1.0–2.0 mSv/y. The country-averaged annual doses of natural radiation in the world have been evaluated using the basic data taken from the UNSCEAR 2000 report. The result shows that total annual exposure doses containing cesium and natural radiation contributions in Fukushima are 2–4 mSv/y, which are close to the natural radiation doses in Europe. The risk coefficient of the public exposure limits, 1 mSv/y, has also been evaluated to be 4.5 × 10 per year. It is lower than that of traffic accidents by two orders of magnitude. These results will be useful to judge how the safety of the Fukushima prefecture is secured.

The indoor deposition of radiocaesium was investigated for 27 wooden houses in eight areas of Kanaya, Mimigai, Ootawa, Ooi, Kamiyama, Kamiura, Ebizawa, and Yoshina in Odaka district of Minami-Soma, Fukushima Prefecture from November 2013 to January 2015. Odaka district is within a 20 km radius of the Fukushima Daiichi nuclear power plant (FDNPP), which used to be designated as a restricted area and has been designated as an evacuation area. Dry smear test was performed over an area of 100 cm on the surface of materials made of wood, glass, metal, and plastic in the rooms and the surface of wooden structure in the roof-space. Approximately 1000 smear samples were collected in total; 89% of the smear samples obtained in the rooms exceeded the detection limit (0.004 Bq/cm) and a maximum value was evaluated to be 1.54 Bq/cm; 77% of the smear samples taken from the wooden structure in the roof-space exceeded the detection limit and a maximum value was evaluated to be 1.14 Bq/cm. Area differences in surface contamination were observed. Assuming that two horizontal phases of the room have uniform surface contamination with the maximum median radioactivity observed in Kamiura (0.1 Bq/cm) for 27 houses investigated, the ambient dose equivalent rate for Cs and Cs in November 2013 was calculated as approximately 0.002 μSv/h.

This paper summarizes research carried out on fruits by the Università Cattolica del Sacro Cuore (UCSC) in Piacenza, Italy. Among the fruit crops studied, strawberry, blackberry, grapevine, apple, pear, and olive, research on strawberry and blackberry was funded by the Food Standard Agency (UK). Fruit plants were grown in pots, kept under tunnels or in open field, and contaminated with Cs and Sr via leaves or via soil. Interception in strawberry plants ranges 39–17 % for Cs, from anthesis (April) to predormancy (November). Leaf-to-fruit translocation occurs to a greater extent for Cs than for Sr. The distribution of contamination in fruit crops is an element-specific process: Cs is preferentially allocated to fruits and Sr to leaves. However, the activity in leaves is also species-specific: fruit species show different leaf-to-fruit translocation. Results on apple, pear, and grape crops indicate that the highest transfer from leaf to fruit occurs in apple crops. Olive plants also show Cs translocation from leaves to trunks. Grapevines grown on mineral soil show a root uptake higher for Sr than for Cs, while strawberries grown on a peat substrate show a root uptake higher for Cs than for Sr. Rinsing directly contaminated fruits removes Sr (36 %) to a greater degree than Cs (24 %). Transfer to olive oil is low. A 57 % of Cs is transferred from grapes to white wine.

Radioactive materials that were released during the nuclear accident contaminated the soil and agricultural products. It has become clear that potassium fertilization is effective for the reducing radiocesium concentrations in agricultural crops. However, apart from reports about potassium, few reports have examined how nitrogen (N), which has a large effect on crop growth, contributes to the radiocesium absorption. Focusing on this point, we studied the effect of nitrogen fertilizer on the radiocesium absorption in soybean seedlings. The concentration of radiocesium in the seed of soybean was higher in nitrogen-fertilized plants than in plants grown without fertilizer. The radiocesium concentration in the aboveground biomass increased as the amount of nitrogen fertilization increased. A comparison of the effects of the different forms of nitrogen treatment shows that the highest radiocesium concentration in the aboveground biomass occurred with ammonium sulfate (approximately 3.7 times the non-N), the next highest absorption occurred with ammonium nitrate (approximately 2.4 times the non-N treatment), followed by calcium nitrate (approximately 2.2 times the non-N treatment). Furthermore, the amount of radiocesium in soil extracts was highest with ammonium-nitrogen fertilization. Further study is required to clarify the factors that incur an increase in radiocesium concentration in response to nitrogen fertilization. Special care is required to start farming soybean on fallow fields evacuated after the accident or on fields where rice has been grown before, which tend to have higher available nitrogen than the regularly cultivated fields.

On April 1, 2012, new Standard Limits for radionuclide concentrations in food were promulgated, superseding the Provisional Regulation Values in Japan set in 2011. The new Standard Limits are calculated based on 1 mSv y of annual internal radiation dose through food ingestion of Cs, Cs, Sr, Pu and Ru, which were detected or possibly released into the environment from the accident at the TEPCO Fukushima Daiichi Nuclear Power Stations (FDNPS). The concentrations of the radionuclides were based on the values of radiocesium (Cs) and of the other radionuclides (Sr, Pu and Ru); the ratio observed in the determination or predicted concentrations in the soils from the FDNPS accident was used for estimating the concentration of the other radionuclides by means of the ratio against Cs. The new Standard Limit of radiocesium in general foods was defined to be 100 Bq kg fresh weight by the Ministry of Health, Labour and Welfare. In the present study the concentration of radiocesium was measured in agricultural products collected mostly in Fukushima-shi and Date-shi, Fukushima Prefecture, in 2012 and 2013. The average concentration of radiocesium in agricultural plants in 2012 was 7.6 (<0.2–40) Bq kg fresh weight, decreasing to 2.0 (<0.1–14) Bq kg fresh weight in 2013, which was approximately one-fourth of the concentration in 2012. The concentration of Sr in agricultural products collected in Fukushima Prefecture in 2013 was 0.0047–0.31 Bq kg fresh weight, which was a similar range to those collected throughout Japan. The concentration ratio of Sr/Cs in the agricultural plants collected from the area 5 km west from the Nuclear Power Stations (difficult-to-return zone) was lower than the predicted Sr/Cs ratio, which was calculated using the ratio in the soils and soil-to-plant transfer factors.

Despite a concentration of exchangeable K of >208 mg kg dry weight in soil, the brown rice grown in Minamisoma City in 2013 had a higher concentration of radiocesium than the new Japanese standard (100 Bq kg) for food. To analyze the factors affecting the radiocesium concentration in brown rice, we carried out pot tests using paddy soil and irrigation water collected in Minamisoma City. Rice seedlings were planted in 5-L pots containing Minamisoma soil, in which the exchangeable K was 125 mg kg dry weight, and were irrigated with tap water or irrigation water collected in Minamisoma City. There was no difference in the Cs-137 concentration in brown rice between the two types of irrigation. Then we grew rice in the Minamisoma soil and two soils collected in Nakadori, Fukushima Prefecture. Cs-137 uptake in the Minamisoma soil was intermediate between the uptake rates in the Nakadori soils, showing that the Minamisoma soil was not special in radiocesium uptake. Finally, we grew rice in soil without radiocesium near the Fukushima Daiichi Nuclear Power Plant in 2014. Although the maximum value of Cs-137 in brown rice was 18 Bq kg, below the standard, radiocesium was attached to the surface of the foliage.

It is more than 4 years since March 11, 2011, and, at this stage, foods that exceed the standard limits of radiocesium are mainly from the wild. Hence, one of the public’s main concerns is how to decrease ingestion of radiocesium from foods they have collected from the wild as well as from their home-grown fruits because radioactivities in these food materials have not been monitored. In this study, we focused on wild edible plants and fruits, and the effects of washing, boiling, and pealing to remove radiocesium were observed. Samples were collected in 2013 and 2014 from Chiba and Fukushima Prefectures, e.g., young bamboo shoots, giant butterbur, and chestnuts. Wild edible plants were separated into three portions to make raw, washed, and boiled samples. For fruit samples (i.e., persimmon, loquat, and Japanese apricot), fruit parts were separated into skin, flesh, and seeds.

It was found that washing of plants is not effective in removing both Cs and K, and that boiling provided different removal effects on plant tissues. The retention factors of Cs and K for thinner plant body sample (leaves) tended to be higher than those for thicker plant body types, e.g., giant butterbur petiole and bamboo shoots. Thus, the boiling time as well as the crop thickness affects radiocesium retention in processed foods. For fruits, Cs concentration was higher in skin than in fruit flesh for persimmon and loquat; however, Japanese apricot showed different distribution.

The role of this study in terms of health physics and radiation protection has been implemented to evaluate the internal dose (relative to the committed equivalent dose) and the dose distribution imaging due to gamma rays (photons) and beta particles emitted from the radioactive Cs-bearing particles in atmospheric aerosol dusts deposited in the lungs via pulmonary inhalation. The PHITS code combined with voxel phantom data (DICOM formats) of human lungs was used.We have dealt with the insoluble radioactive Cs-bearing particles of water (about 2.6 μm diameter) migrated onto any of six regions, ET1, ET2, BB, AI-bb, LNET, and LNTH, in a respiratory system until dropping into blood vessels. Source parameters were those of an adult male breathing a typical air volume outdoors; in the simulated atmosphere (such as systematically setting up a field) those particles would be released on 21:10 March 14 to 9:10 March 15, 2011 in Tukuba, Japan, as a filter sampling condition already reported by Adachi et al. In this chapter, we discuss the internal dose and the dose distribution imaging in each voxel phantom for human lung tissues corresponding to the respiratory tracts of BB and AI-bb, respectively.

After the Fukushima Nuclear Power Plant accident, one of the main issues at stake was the potential intake of contaminated foodstuff by residents of the affected areas. In this context, the importance of the management of the internal exposure by food intake has emerged. For this purpose, a system was developed for estimating the amount of the radioactivity ingested through the diet in order to manage the internal exposure evolution of exposed people. The ultimate goal of this system is to consider all the radiation exposure data including medical exposure in an integrated manner.

In this perspective, a tool that was used for internal exposure assessment in Europe after the Chernobyl disaster has been adapted to be suitable to Japanese diet behavior. The tool was implemented in a Web application in order to estimate the amount of radioactivity in the dish and to manage the internal exposure history of the individuals. This system automatically collects the test results of radionuclide in foods available on the web.

It manages the individual internal exposure history estimating the amount of radioactivity in the ingested dish. The developed application enables individual to manage his/her protection by checking radioactivity ingestion history and determining to eat or not the dish according to the amount of radioactivity in the dish. This system, which has the potential to contribute to the radiation protection culture of people living in the contaminated areas of Fukushima Prefecture, has been evaluated by specialists of radiation protection. The following step will be the test of the system by the individuals themselves.