Earticle

초록

영어

Massive environmental monitoring has been conducted continuously since the Fukushima Daiichi Nuclear Power accident in March of 2011 by different monitoring methods that have different features together with migration studies of radiocesium in diverse environments. These results have clarified the characteristics of radiological environments and their temporal change around the Fukushima site. At three months after the accident, multiple radionuclides including radiostrontium and plutonium were detected in many locations; and it was confirmed that radiocesium was most important from the viewpoint of long-term exposure. Radiation levels around the Fukushima site have decreased greatly over time. The decreasing trend was found to change variously according to local conditions. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2–3 on average; those in pure forest have decreased more closely to physical decay. The main causes of air dose rate reduction were judged to be radioactive decay, movement of radiocesium in vertical and horizontal directions, and decontamination. Land-use categories and human activities have significantly affected the reduction tendency. Difference in the air dose rate reduction trends can be explained qualitatively according to the knowledge obtained in radiocesium migration studies; whereas, the quantitative explanation for individual sites is an important future challenge. The ecological half-lives of air dose rates have been evaluated by several researchers, and a short-term half-life within 1 year was commonly observed in the studies. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of an extensive car-borne survey dataset, which enabled the prediction with confidence intervals. Different types of contamination maps were integrated to better quantify the spatial data. The obtained data were used for extended studies such as for identifying the main reactor that caused the contamination of arbitrary regions and developing standard procedures for environmental measurement and sampling. Annual external exposure doses for residents who intended to return to their homes were estimated as within a few millisieverts. Different forms of environmental data and knowledge have been provided for wide spectrum of people. Diverse aspects of lessons learned from the Fukushima accident, including practical ones, must be passed on to future generations.

목차

ABSTRACT
Introduction
Large scale environmental monitoring after Fukushima NPP accident
1. Air dose rate
2. Radionuclide ground deposition
Initial contamination conditions
Temporal change in radiological environments
1. Air dose rate
2. Deposited radionuclides
3. Causes of air dose rate reduction and influencing factors
4. Ecological half-life and prediction model
Extended studies of environmental monitoring
1. Integration of different monitoring results
2. Identification of origin of deposited radionuclides
3. Practical protocols for sampling and monitoring
External exposure dose evaluation for residents
1. Evaluation based on simple assumptions
2. Evaluation for residents returning to evacuation zone
3. Dose reduction factor by house
Preservation and provision of environmental data, information and samples
Summary and future challenges
Acknowledgment
References

키워드

저자

• Kimiaki Saito [ Japan Atomic Energy Agency ] Corresponding author
• Satoshi Mikami [ Japan Atomic Energy Agency ]
• Masaki Andoh [ Japan Atomic Energy Agency ]
• Norihiro Matsuda [ Japan Atomic Energy Agency ]
• Sakae Kinase [ Japan Atomic Energy Agency ]
• Shuichi Tsuda [ OECD Nuclear Energy Agency ]
• Tetsuro Sato [ Hitachi Solutions East Japan Ltd. ]
• Akiyuki Seki [ Japan Atomic Energy Agency ]
• Yukihisa Sanada [ Japan Atomic Energy Agency ]
• Haruko Wainwright-Murakami [ Lawrence Berkeley National Laboratory ]
• Kazuya Yoshimura [ Japan Atomic Energy Agency ]
• Hiroshi Takemiya [ Japan Atomic Energy Agency ]
• Junko Takahashi [ University of Tsukuba, Japan ]
• Hiroaki Kato [ University of Tsukuba, Japan ]
• Yuichi Onda [ University of Tsukuba, Japan ]

참고문헌

발행기관

간행물

표지보기 관심저널 등록

• 간행물명

  방사선방어학회지 [Journal of Radiation Protection and Research]

• 간기

  계간

• pISSN

  2508-1888

• 수록기간

  1976~2026

• 등재여부

  KCI 등재,SCOPUS

• 십진분류

  KDC 559 DDC 629