A Case Study about Counting Uncertainty of Radioactive Iodine (<sup>131</sup>I) in Public Waters by Using Gamma Spectrometry

Cho, Yoonhae; Seol, Bitna; Min, Kyoung Ok; Kim, Wan Suk; Lee, Junbae; Lee, Soohyung; Cho, Yoonhae; Seol, Bitna; Min, Kyoung Ok; Kim, Wan Suk; Lee, Junbae; Lee, Soohyung

doi:2016.38.1.42

The Korean text of this paper can be translated into multiple languages on the website of http://jksee.or.kr through Google Translator.

J Korean Soc Environ Eng > Volume 38(1); 2016 > Article

Original Paper

J Korean Soc Environ Eng 2016;38(1): 42-46. doi: https://doi.org/10.4491/KSEE.2016.38.1.42

감마분광분석을 이용한 환경 중 방사성요오드(¹³¹I)의 측정 불확도에 관한 사례 연구

조윤해, 설빛나, 민경옥, 김완석, 이준배, 이수형

국립환경과학원 금강물환경연구소

A Case Study about Counting Uncertainty of Radioactive Iodine (¹³¹I) in Public Waters by Using Gamma Spectrometry

Yoonhae Cho, Bitna Seol, Kyoung Ok Min, Wan Suk Kim, Junbae Lee, Soohyung Lee

Geum River Environment Research Center, National Institute of Environmental Research

Corresponding author

Yoonhae Cho ,Tel: 043-730-5655 , Fax: 043-733-9408, Email: yh.cho@korea.kr

Received: October 5, 2015; Revised: November 4, 2015; Accepted: January 25, 2016. Published online: January 31, 2016.

ABSTRACT

The radioactive iodine (¹³¹I) presents in the environment through the excrete process of nuclear medicine patients. In the detecting of low level of ¹³¹I in the public water, the counting uncertainty has an effect on the accuracy and reliability of detecting ¹³¹I radioactivity concentration. In this study, the contribution of sample amount, radioactivity concentration and counting time to the uncertainty was investigated in the case of public water sample. Sampling points are public water and the effluents of a sewage treatment plant at Sapkyocheon stream, Geumgang river. In each point, 1, 10 and 20 L of liquid samples were collected and prepared by evaporation method. The HPGe (High Purity Germanium) detector was used to detect and analyze emitted gamma-ray from samples. The radioactivity concentration of ¹³¹I were in the range of 0.03 to 1.8 Bq/L. The comparison of the counting uncertainty of the sample amount, 1 L sample is unable to verify the existence of the ¹³¹I under 0.5 Bq/L radioactivity concentration. Considering the short half-life of ¹³¹I (8.03 days), a method for measuring 1 L sample was used. However comparing the detecting and preparing time of 1, 10 L respectively, detecting 10 L sample would be an appropriate method to distinguish ¹³¹I concentration in the public water.

Key Words: Radioactive Iodine (¹³¹I), Counting Uncertainty, Environmental Radiation, Gamma Spectrometry