• Title/Summary/Keyword: 최소 검출 방사능 농도

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Determination of Minimum Detectable Activity in Environmental Samples (환경방사능 측정에서의 검출한계치의 정량적 고찰 및 최소검출방사능 농도 계산)

  • Lee, Myung-Ho;Shin, Hyun-Sang;Hong, Kwang-Hee;Cho, Young-Hyun;Lee, Chang-Woo
    • Journal of Radiation Protection and Research
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    • v.24 no.3
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    • pp.171-184
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    • 1999
  • In this paper, using statistical theory the basic concepts and the formulars of lower limit of detection were deasribed. Assuming that risks of 5% are acceptable (95% confidence level), lower limits of detection were calculated on the measuring apparatus for alpha, beta and gamma nuclides. Also, on the basis concepts of lower limit of detection, the MDA values were calculated for the radionuclides detected easily in the environment. These results make it possible to evaluate confidence limits on the radioanalytical results in the environmental sample.

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Survey Study on Radioactivity of Domestic Fishery Product (국내 시중 유통 수산물에 대한 방사능 농도 조사)

  • Kim, Chang-Jong;Lim, Chung-seop;Lee, Wanno;Jang, Mee;Ji, Young-Yong;Chung, Kun-Ho;Kang, and Mun-Ja
    • Korean Journal of Food Science and Technology
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    • v.47 no.6
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    • pp.789-792
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    • 2015
  • Samples of fishery products were tested for radioactivity by using the intake frequency data from Korea Health Statistics. The radioactivity of $^{40}K$, $^{137}Cs$, $^{134}Cs$, and $^{131}I$ was analyzed using gamma spectrometry with a simplified sample pre-treatment procedure. The radioactivity range for $^{40}K$ was 21.9-3050 Bq/kg, whereas the radioactivities of $^{137}Cs$, $^{134}Cs$, and $^{131}I$ were under minimum detectable activity which were in the range of 0.140-1.97, 0.0900-1.89 and 0.124-1.94 Bq/kg, respectively, for the three species. The results suggest that the Fukushima accident did not have a significant impact on domestic fishery products, which were analyzed during the period from 2013 to 2015. Additionally, there seemed to be no significant impact of additional exposure dose by the analyzed radionuclides.

Minimum Detectable Radioactivity Concentration of Atmospheric Particulate Measurement System for Nuclear Test Monitoring (핵활동 감시를 위한 대기 입자 측정시스템의 최소검출 방사능 농도 결정)

  • Kim, Jong-Soo;Yoon, Suk-Chul;Shin, Jang-Soo;Kwack, Eun-Ho;Choi, Jong-Seo
    • Journal of Radiation Protection and Research
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    • v.22 no.2
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    • pp.111-117
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    • 1997
  • Recently, the conclusion of Comprehensive Test Ban Treaty(CTBT) is globally constructing a network system for nuclear test monitoring. The radionuclide experts of the Conference on Disarmament recommended that the detection of nuclear debris in the atmosphere was an essential factor of nuclear test monitoring and proposed the technical requirements. Based on those requirements, atmospheric radionuclide monitoring system to detect nuclear debris generated from the nuclear explosion test was composed. The system is comprised of high volume air sampler(HVAS), filter paper presser and high purity germanium detector(HPGe). Minimum detectable concentrations(MDCs) of the key nuclides requiring in CTBT monitoring strategies are determined by considering of decay time, counting time and flow rate of the high volume air sampler for the rapid explosion and the optimum measurement condition. The results were selected $10{\pm}$2h, $20{\pm}$2h and $850{\pm}50m^3$/h as parameters, respectively. The relation between the natural air-borne radionuclide concentration of $^{212}Pb$ and MDC were calculated which gave effect in the Compton continuum baseline due to those nuclides in the gamma-ray spectroscopy. These results can be used as an actually tool in the CTBT monitoring strategies.

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Analysis of Minimum Detectable Activity Concentration of Water Samples and Evaluation of Effective Dose (물 시료의 최소검출가능 농도 분석과 유효선량 평가)

  • Jang, Eun-sung;Kim, Yang-su;Lee, Sun-young;Kim, Jung-Soo
    • Journal of the Korean Society of Radiology
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    • v.14 no.7
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    • pp.857-862
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    • 2020
  • In March 2011, a tsunami off Japan caused radioactive material that had seeped into the sea from the Fukushima nuclear accident to flow to the Pacific Ocean, causing pollution to sea life. For a comparative evaluation with the area surrounding the site of a nuclear power plant by the release of radioactive materials, an area 20 to 30 km away from the emergency protection plan area was selected as a comparative point considering weather conditions, population distribution, etc. In addition, the government intends to analyze the minimum detection radiation received by residents around the nuclear power plant and evaluate the effective dose. Analysis of tritium radiation from water samples showed that most of the samples were not detected and that 0.0014 % to 0.777 % of the annual legal standard of 1 mSv for the general public had little effect on the human body. Therefore, the measurement and analysis of water samples around the nuclear power plant site is expected to help relieve anxiety, such as exposure to the general public and neighboring residents due to radiation release.

A Study of Determination of Minimum Detectable Activity at Measuring of Pu Isotopes in Environmental Samples (환경시료 중 Pu 측정에서 최소검출방사능 농도 산출에 대한 연구)

  • Lee, Myung-Ho;Cho, Young-Hyun;Choi, Gun-Sik;Lee, Chang-Woo;Shin, Hyun-Sang
    • Analytical Science and Technology
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    • v.14 no.1
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    • pp.64-71
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    • 2001
  • In this paper, the formula of lower limit of detection considering the measuring time of sample and background was derived using the basic concepts of lower limit of detection. Among parameters affecting the determination of MDA value, the MDA values were calculated with variation of amount of sample and measuring time of sample and background. The results of adequate division between the measuring time of sample and that of background studied in this research make it possible to evaluate confidence limits on the radio analytical results in the environmental sample.

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Survey of radioactive contamination in imported foodstuffs (수입 식품중의 방사능 오염실태 조사)

  • Lee, Wan-No;Lee, Haeng-Pil;Chung, Kun-Ho;Kim, Hee-Reyoung;Cho, Young-Hyun;Choi, Geun-Sik;Lee, Chang-Woo;Chung, Hyung-Wook;Lee, Eun-Ju;Sho, You-Sup;Lee, Jong-Ok
    • Journal of Radiation Protection and Research
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    • v.31 no.3
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    • pp.141-148
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    • 2006
  • Surveys of radioactive contamination were performed for imported foodstuffs in 2003. The following samples among imported foodstuffs were selected from markets and Korea Food and Drug Administration(KFDA); the imported samples from country associated with the Chernobyl nuclear accident, the samples produced around the nuclear power plants or nuclear tests, the foodstuffs reported as radioacitive contamination materials in foreign country. After pretreatments such as drying and homogenization, samples were analyzed. The $^{137}Cs$ radionuclide was only measured among the regulation radionuclides($^{137}Cs,\;^{134}Cs,\;^{131}I$) of food code. All foodstuffs except Inonotus Obliquus(Chaga mushooms) are less than 17.0 Bq/kg or below the minimum detectable activity(MDA). The activity concentrations of Chaga mushrooms from Russia ranged up to 131.25 Bq/ltg which is almost 35 % of the maximum permitted level of food code. The fraction of imported foodstuffs having meaningful radioactivity is small, however, the radioactive contamination survey of imported foodstuffs is still needed.

Determination of 129I in simulated radioactive wastes using distillation technique (증류법을 이용한 모의 방사성폐기물 중 129I 의 정량)

  • Choi, Ke-Chon;Song, Byung-Cheol;Han, Sun-Ho;Park, Yong-Joon;Song, Kyu-Seok
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.9 no.3
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    • pp.141-148
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    • 2011
  • It is clarified in the radioactive waste transfer regulation that the concentration of radioactive waste for the major radio nuclide has to be examined when radioactive waste is guided to the radioactive waste stores. In case of the low level radioactive waste sample, the analytical results of radioactive waste concentration frequently show a value lower than minimum detectable activity (MDA). Since the MDA value basically depends on the amount of a sample, background value, measurement time, counting efficiency, and etc, it would be necessary to increase a sample amount with a intention of minimizing MDA. In order to measure a concentration of $^{129}I$ in low and medium level radioactive waste, $^{129}I$ was collected by using a distillation technique after leaching the simulated radioactive waste sample with a non-volatile acid. The recovery of $^{129}I$ measured was compared with that measured with column elution technique which is a conventional method using an anion-exchange resin. The recovery of inactive iodide by using the distillation method and column elution were found as $86.5{\pm}0.9%$ and $87.3{\pm}2.7%$, respectively. The recovery and MDA value calculated for distillation technique when 100 g of extracted solution of $^{129}I$ was taken, were found to be $84.6{\pm}1.6%$ and $1.2{\times}10^{-4}Bq/g$, respectively. Consequently, the proposed technique with simplified process lowered the MDA value more than 10 times compared to the column elution technique that has a disadvantage of limited sampling amount.

Cesium Radioisotope Measurement Method for Environmental Soil by Ammonium Molybdophosphate (환경토양에서 몰리브도인산 암모늄을 이용한 세슘 동위원소 평가방법)

  • Choe, Yeong-hun;Seo, Yang Gon
    • Clean Technology
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    • v.22 no.2
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    • pp.122-131
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    • 2016
  • 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.

Factors Affecting the Minimum Detectable Activity of Radioactive Noble Gases (방사성 노블가스 측정을 위한 최소검출방사능 산출의 조절인자)

  • Park, Ji-young;Ko, Young Gun;Kim, Hyuncheol;Lim, Jong-Myoung;Lee, Wanno
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.16 no.3
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    • pp.301-308
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    • 2018
  • Anthropogenic radioactive noble gases formed by nuclear fission are significant indicators used to monitor the nuclear activity of neighboring countries. In particular, radioactive xenon, owing to its abundant generation and short half-life, can be used to detect nuclear testing, and radioactive krypton has been used as a tracer to monitor the reprocessing of nuclear fuels. Released radioactive noble gases are in the atmosphere at infinitesimal amounts due to their dilution in the air and their short half-life decay. Therefore, to obtain reliable and significant data when performing measurement of noble gases in the atmosphere, the minimum detectable activity (MDA) for noble gases should be defined as low as possible. In this study, the MDA values for radioactive xenon and krypton were theoretically obtained based on the BfS-IAR system by collecting both noble gases simultaneously. In addition, various MDA methods, confidence level and analysis conditions were suggested to reduce and optimize MDA with an assessment of the factors affecting MDA. The current investigation indicated that maximizing the pretreatment efficiency and performance maintenance of the counter were the most important aspects for Xe. In the case of Kr, since sample activities are much higher than those of Xe, it is possible to change the target MDA or to simplification of the analysis system.