Discussion; Making databases of parameter values of radionuclide transfer in environment and application for biospheric dose assessment

Takahashi, Tomoyuki*; Uchida, Shigeo*; Takeda, Seiji; Nakai, Kunihiro*

KURNS-EKR-11, p.97 - 102, 2021/03

https://www.rri.kyoto-u.ac.jp/PUB/report/09_kurns/temp/kurns-ekr-011.pdf

This paper outlines the status of IAEA database compilation for migration parameters depending elements in a biosphere such as soil-to-plant transfer factor and bioconcentration factor of marine products, and the status of utilization of the database in dose evaluation of radioactive waste disposal in Japan. Additionally, in the case of applying a new database to the dose evaluation for future radioactive waste disposal in a specific area. We summarized the opinions of specialists and result of general discussion about future strategies to make a new database for their parameters, perspectives to be considered in it, issues, etc.

Observation of morphological abnormalities in silkworm pupae after feeding CsCl-supplemented diet to evaluate the effects of low dose-rate exposure

Tanaka, Sota; Kinouchi, Tadatoshi*; Fujii, Tsuguru*; Imanaka, Tetsuji*; Takahashi, Tomoyuki*; Fukutani, Satoshi*; Maki, Daisuke*; Notomi, Akihiro*; Takahashi, Sentaro*

Scientific Reports (Internet), 10, p.16055_1 - 16055_7, 2020/09

https://doi.org/10.1038/s41598-020-72882-y

Since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, morphological abnormalities of the lepidopteran insects have been reported. However, it is unclear whether the abnormalities were caused directly by radiation because they did not study on absorbed dose and dose-effect relationship. In this study, we conducted an internal exposure experiment on silkworm using CsCl-supplemented artificial diet and estimated the absorbed dose to evaluate the morphological abnormalities in silkworm. The ratio of wing to whole body of pupae was compared between the CsCl-exposured and control groups and no significant differences were observed between the groups. This result suggest that morphological abnormalities in lepidopterans are unlikely due to direct radiation effects from Cs contamination after the FDNPP accident.

Radioactive cesium contamination of arthropods and earthworms after the Fukushima Daiichi Nuclear Power Plant Accident

Tanaka, Sota; Adachi, Taro*; Takahashi, Tomoyuki*; Takahashi, Sentaro*

Low-Dose Radiation Effects on Animals and Ecosystems; Long-Term Study on the Fukushima Nuclear Accident, p.43 - 52, 2020/00

https://doi.org/10.1007/978-981-13-8218-5_4

To understand the behavior of radiocesium in terrestrial invertebrates, chronological changes in the concentration of radiocesium in arthropods and earthworms from different trophic levels were investigated after the Fukushima Daiichi Nuclear Power Plant accident. The median radiocesium concentrations in the rice grasshopper, Oxya yezoensis, and the Emma field cricket, Teleogryllus emma, were 0.46 and 0.15 Bq/g fw in 2012, respectively, which dropped continuously to 0.05 and 0.01 Bq/g fw in 2016. In contrast, no significant reduction in radiocesium concentration was observed in the Joro Spider, Nephila clavata, in which the concentration was 0.31 Bq/g fw in 2012 and remained at 0.14 Bq/g fw in 2016. The comparison of radiocesium concentrations at each trophic level showed that the amount in detritivorous earthworms was 85 times higher than in herbivorous grasshoppers. This suggests that detritus food web could be a primary pathway of radiocesium through food webs.

Development of field estimation technique and improvement of environmental tritium behavior model

Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.

Plasma and Fusion Research (Internet), 14(Sp.2), p.3405099_1 - 3405099_4, 2019/06

https://doi.org/10.1585/pfr.14.3405099

The Large Helical Device of the National Institute for Fusion Science started D-D experiments in 2017. To ensure the safety of the facility, it is important to develop evaluation methods for environmental tritium transfer. Tritiated water (HTO) in atmosphere and soil is transferred to plants, and organically bound tritium (OBT) is formed by photosynthesis. Prediction of OBT formation is important, because OBT accumulates in plants and causes dose through ingestion. The objective of this study is to estimate environmental tritium transfer using a simple compartment model and practical parameters. We proposed a simple compartment model consisting of air-soil-plant components, and tried to validate the model by comparison with a sophisticated model, SOLVEG. In this study, we plan to add wet deposition to the model and obtain parameters from measurements of soil permeability and tritium concentrations in air, soil and plants. We also establish rapid pretreatment methods for OBT analysis.

Long-term predictions of ambient dose equivalent rates after the Fukushima Daiichi Nuclear Power Plant accident

Kinase, Sakae; Takahashi, Tomoyuki*; Saito, Kimiaki

Journal of Nuclear Science and Technology, 54(12), p.1345 - 1354, 2017/12

https://doi.org/10.1080/00223131.2017.1365659

Prediction of ambient dose equivalent rates for the next 30 years after the accident

Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi*; Yamamoto, Hideaki; Saito, Kimiaki

Proceedings of International Symposium on Radiological Issues for Fukushima's Revitalized Future, p.40 - 43, 2015/00

http://www.rri.kyoto-u.ac.jp/anzen_kiban/outcome/Symposium'15_Proceedings_EN.pdf#page=50

To support recovery and rehabilitation in Fukushima, prediction models have been developed for ambient dose equivalent rate distribution within the 80 km-radius around the Fukushima Daiichi Nuclear Power Plant. The prediction models that are based on bi-exponential functions characterized by ecological half-lives of radioactive caesium for land-use, enable Fukushima residents to obtain distribution maps of ambient dose equivalent rates for the next 30 years after the accident. Model parameters were evaluated using ambient dose equivalent rates through car-borne surveys. The model parameters in deciduous and evergreen forest areas were found to be different from those in other areas. In addition, it was found that distribution maps of ambient dose equivalent rates for the next 30 years after the accident, created by the prediction models would be useful for follow-up of the radiological situation.

Behavior of environmental tritium at NIFS Toki Site of Japan

Sugihara, Shinji*; Tanaka, Masahiro*; Tamari, Toshiya*; Shimada, Jun*; Takahashi, Tomoyuki*; Momoshima, Noriyuki*; Fukutani, Satoshi*; Atarashi-Andoh, Mariko; Sakuma, Yoichi*; Yokoyama, Sumi*; et al.

Fusion Science and Technology, 60(4), p.1300 - 1303, 2011/11

https://doi.org/10.13182/FST11-A12669

The purpose of this study is to develop the technique to evaluate the environmental tritium behavior of the nuclear facility origin. Tritium concentrations of river water, precipitation and ground water around the NIFS site were determined by low background liquid scintillation measurement system combined with the electrolysis using solid polymer electrolyte. The electric conductivity and flow rate of the river and isotopic ratio of oxygen and hydrogen of water samples were also measured. The tritium concentrations in precipitation showed the seasonal variation and the range were 0.09-0.78 Bq/L. The tritium concentrations of river water and ground water were almost constant, 0.34 and 0.24 Bq/L respectively. The simple dynamic model for the site around the NIFS facilities was developed using measured data, and the behavior of tritium was simulated.

MOGRA-DB; Database system for migration prediction code MOGRA

Amano, Hikaru; Ikeda, Hiroshi*; Sasaki, Toshihisa*; Matsuoka, Shungo*; Kurosawa, Naohiro*; Takahashi, Tomoyuki*; Uchida, Shigeo*

KEK Proceedings 2003-11, p.239 - 244, 2003/11

A Code MOGRA (Migration Of GRound Additions) is a migration prediction code for toxic ground additions including radioactive materials in a terrestrial environment, which consists of computational codes that are applicable to various evaluation target systems, and can be used on personal computers. The computational code has the dynamic compartment analysis block at its core, the graphical user interface (GUI) for model formation, computation parameter settings, and results displays. The code MOGRA has varieties of databases, which is called MOGRA-DB. Another additional code MOGRA-MAP can take in graphic map and calculate the square measure about the target land.

Application of MOGRA for migration of contaminants through different land utilization areas

Amano, Hikaru; Takahashi, Tomoyuki*; Uchida, Shigeo*; Matsuoka, Shungo*; Ikeda, Hiroshi*; Hayashi, Hiroko*; Kurosawa, Naohiro*

JAERI-Conf 2003-010, p.112 - 121, 2003/09

https://jopss.jaea.go.jp/pdfdata/JAERI-Conf-2003-010.pdf

The functionality of MOGRA is being verified by applying it in the analyses of the migration rates of radioactive substances from the atmosphere to soils and plants and flow rates into the rivers. This has been achieved by also taking their mode classifications into consideration. In this report, a hypothetical combination of land usage was supposed to check the function of MOGRA. The land usage was consisted from cultivated lands, forests, uncultivated lands, urban area, river, and lake. Each land usage has its own inside model which is basic module. Also supposed was homogeneous contamination of the surface land from atmospheric deposition of Cs-137 (1.0 Bq/m). The system can analyze the dynamic changes of Cs-137 concentrations in each compartment, fluxes from one compartment to another compartment.

Overview of the 3rd phase crossover research on migration of radionuclides in biosphere

Uchida, Shigeo*; Amano, Hikaru; Takahashi, Tomoyuki*; Chiba, Masaru*; Hisamatsu, Shunichi*; Enomoto, Shuichi*; Matsumoto, Shiro*

JAERI-Conf 2003-010, p.25 - 31, 2003/09

https://jopss.jaea.go.jp/pdfdata/JAERI-Conf-2003-010.pdf

In the 3rd Stage Crossover Research (1998 to 2003), a project on Development of a dynamic transfer model of radionuclides in the soil ecosphere,is currently being promoted. The following five researches are carried out in this project. 1) Research into the forms of existence of nuclides and their change in the soil (NIRS and JAERI), 2) Research into the transition behavior of radionuclides in plants (IES, RIKEN and NIRS), 3) Research into the relation to the microorganism and on environmental remediation (RIKEN, JAERI and NIRS), 4) Research on the migration of radionuclides from atmosphere to soil and plant (MRI and JAERI), and 5) Database construction on transfer parameters (JAERI, NIRS and MRI). JAERI, MRI and NIRS are working on the development of a dynamic transfer model such as MOGRA for radionuclides on the basis of a gained knowledge about the environmental behavior through cooperation with universities, etc. This model is also capable of the predicting the behavior of materials that are harmful to the environment such as hazardous heavy metals discharged in the soil ecosphere. In this presentation, we will overview the ourcome of the 3rd stage research.