환경토양에서 몰리브도인산 암모늄을 이용한 세슘 동위원소 평가방법

최영훈; 서양곤; Yeong-hun Choe; Yang Gon Seo

Clean Technology, Vol.22, No.2, 122-131, June, 2016

DOI10.7464/ksct.2016.22.2.122 Export Citation

환경토양에서 몰리브도인산 암모늄을 이용한 세슘 동위원소 평가방법

Cesium Radioisotope Measurement Method for Environmental Soil by Ammonium Molybdophosphate

최영훈^{1, 2}, 서양곤^{3, †}

¹경상대학교 대학원 환경보전학과, 52828 경남 진주시 진주대로 501
²신고리원전환경감시센터, 45014 울산광역시 울주군 서생면 해맞이로 894
³경상대학교 화학공학과/공학연구원, 52828 경남 진주시 진주대로 501

Yeong-hun Choe^{1, 2}, and Yang Gon Seo^{3, †}

¹Department of Environment Protection, Graduate School, Gyeongsang National University, 501 Jinju-daero, Jinju-si, Gyeongnam 52828, Korea
²Environment Radiation Private Supervisory Cente, SIN Kori Nuclear Power Plant, 894 Haemaji-ro, Seosaeng-myeon, Ulju-gun, Ulsan 45014, Korea
³Department of Chemical Engineering, ERI, Gyeongsang National University, 501 Jinju-daero, Jinju-si, Gyeongnam 52828, Korea

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초록

세슘 동위원소, 134Cs와 137Cs는 대기 핵실험 및 원자력발전소의 배출물로부터 기인하는 인공방사성 핵종 연구에 매우 중요하다. 본 연구에서는 최소검출방사능(minimum detection activity, MDA)을 낮추기 위해 137Cs 및 화학적, 환경적 거동이 동일한 134Cs를 이용하여 환경측정실험실 절차서에 따른 일반적인 환경방사능 분석을 수행하였다. 원자력발전소 주변 고산지대 환경토양을 채취하였고, 세슘 동위원소를 화학적으로 추출.농축하기 위한 방법으로 세슘동위원소와 흡착특성이 높은 Ammonium Molybdophosphate (AMP) 공침법을 토양 전처리 과정에 도입하였다. 방사능 농도는 감마선 분광광도법을 이용하여 분석하였다. 감마 에너지 스펙트럼에서 40K 방사능 농도가 증가함에 따라 134Cs 및 137Cs의 MDA가 증가하였다. 따라서 토양으로부터 자연방사성 핵종이 제거된다면 세슘의 MDA가 줄어들 것이고, 환경토양에서 137Cs의 농도를 효과적으로 측정할 수 있다. 한국원자력안전기술원의 표준 토양 실험에서는 40K의 방사능 농도가 평균 84% 이상 제거되었고, 134Cs의 MDA는 2배 줄어들었다. 137Cs의 방사능 농도는 82% 이상 회수되었다. 한편 환경토양을 이용한 시료에서는 AMP 공침법이 직접법에 비해 40K는 최대 180배 제거되었고, 또한 134Cs의 MDA는 5배 감소하였다. 137Cs의 회수율은 54.54%에서 70.26%를 나타내었다. MDA와 회수율을 고려할 때 AMP 공침법은 매우 낮은 농도의 세슘분석에 효과적이다.

Caesium radioisotopes, 134Cs and 137Cs which come from the atmospheric nuclear tests and discharges from nuclear power plants, are very important to study artificial radioactivity. In this work, in order to lower the minimum detection activity (MDA) we investigated environmental radioactivity according to the Environment Measurement Laboratory procedure by 137Cs and 134Cs which is similar to chemical and environmental behaviors of 137Cs. The environmental soils in high mountain areas near nuclear power plant were collected, and an Ammonium Molybdophosphate (AMP) precipitation method, which showed high selectivity toward Cs+ ions, was applied to chemically extract and concentrate Caesium radioisotopes. Radioactivity was estimated by a gamma-ray spectrometry. In gamma energy spectrum, with an increasing of 40K radioactivity, it increased the MDA of 134Cs and 137Cs. Therefore, if the natural radionuclides were removed from the soil samples, the MDA of Caesium may be reduced, and the contents of 137Cs of in the environmental soils can effectively be estimated. In the standard soil sample of Korea Institute of Nuclear Safety, radioactivity of 40K was removed more than 84% on average, and the MDA of 134Cs was reduced 2 times. The content of 137Cs was recovered over 84%. On the other hand, in environmental soils, AMP precipitation method showed removal ratio of 40K up to 180 times, which reduced the MDA about 5 times smaller than those of Direct method. 137Cs recovery ratio showed from 54.54% to 70.06%. When considering the MDA and recovery ratio, AMP precipitation method is effective for detection of Caesium radioisotopes in low concentration.

Keywords:Environmental soil;Caesium radioisotope;Minimum detection activity;Ammonium molybdophosphate;Gamma-ray spectrometry

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[1] Perkins RW, Nielsen JM, Health Phys., 11(12), 1297 (1965)

[2] Lenerer CM, Shirley VS, Table of Isotopes, 7th ed., John Wiley and Sons, New York (1978).

[3] http://en.wikipedia.org/wiki/Nuclear_fission_product (Accessed Mar. 2016).

[4] http://global.britanica.com/science/nuclear-fission (Accessed Mar. 2016).

[5] Regulations on Radioactive Rays Environment Investigation and Environmental Impact Assessment of Radioactive Rays Around Nuclear Use Facilities, Korea (Nov. 2014).

[6] Environment Radiation Private Supervisory Center, Report No. 15 (Dec. 2004).

[7] Pusan National University, “Results of Service on Cesium Concentration Assessment ai Alpine Region Around Kori Nuclear Power Plant,” Report (Jun. 2008).

[8] EG&G ORTEC, “Modular Pulse-Processing Electronics and Semiconductor Radiation Detectors,” Oak Ridge (1998).

[9] Mimura H, Saito M, Akiba K, Onodera Y, J. Nucl. Sci. Technol., 38, 872 (2001)

[10] Senoh M, Abe M, Suzuki T, Ion Exchange, Kodansha, Tokyo (1991).

[11] Abe M, Japan Anal., 23, 1561 (1974)

[12] Moens L, Hoste L, Int. J. Appl. Radiat. Isot., 34, 1085 (1983)

[13] Friedmann H, Health Phys., 77(3), 309 (1999)

[14] Brodsky A, Gallagher RG, Radiat. Prot. Manag., 8, 64 (1991)

[15] Seymour R, Sergent F, Knight K, Kyker B, Radioactivity Radiochem., 3, 14 (1992)

[16] Cox FM, Guenther CF, Health Phys., 69(1), 121 (1995)

[17] Jang E, J. Korean Soc. Radiol., 5(1), 5 (2011)

[18] Currie LA, Anal. Chem., 40, 586 (1968)

[19] Korea Institute of Nuclear Safety, “The Annual Report on the Environmental Radiological Surveillance and Assessment around the Nuclear Facilities,” p. 46 (2008).

[20] Ahn JK, Kim JS, Lee HM, Kim H, Kim TH, Park JN, Kang YS, Lee HS, Kim SJ, Park JY, Ryu SY, Kim HC, Kang WG, Kim SK, Appl. Radiat. Isot., 69, 1294 (2011)