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Original Research

The Transport Characteristics of 238U, 232Th, 226Ra, and 40K in the Production Cycle of Phosphate Rock

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초록

영어

Background: Phosphate rock and its by-product are widely used in various industries to produce phosphoric acid, gypsum, gypsum board, and fertilizer. Owing to its high level of natural radioactive nuclides (e.g., 238U and 226Ra), the radiological safety of workers who work with phosphate rock should be systematically managed. In this study, 238U, 232Th, 226Ra, and 40K levels were measured to analyze the transport characteristics of these radionuclides in the production cycle of phosphate rock. Materials and Methods: Energy dispersive X-ray fluorescence and gamma spectrometry were used to determine the activity of 238U, 232Th, 226Ra, and 40K. To evaluate the extent of secular disequilibrium, the analytical results were compared using statistical methods. Finally, the distribution of radioactivity across different stages of the phosphate rock production cycle was evaluated. Results and Discussion: The concentration ratios of 226Ra and 238U in phosphate rock were close to 1.0, while those found in gypsum and fertilizer were extremely different, reflecting disequilibrium after the chemical reaction process. The nuclide with the highest activity level in the production cycle of phosphate rock was 40K, and the median 40K activity was 8.972 Bq·g-1 and 1.496 Bq·g-1, respectively. For the 238U series, the activity of 238U and 226Ra was greatest in phosphate rock, and the distribution of activity values clearly showed the transport characteristics of the radionuclides, both for the byproducts of the decay sequences and for their final products. Conclusion: Although the activity of 40K in k-related fertilizer was relatively high, it made a relatively low contribution to the total radiological effect. However, the activity levels of 226Ra and 238U in phosphate rock were found to be relatively high, near the upper end of the acceptable limits. Therefore, it is necessary to systematically manage the radiological safety of workers engaged in phosphate rock processing.

목차

ABSTRACT
 Introduction
 Materials and Methods
  1. Sample pretreatment
  2. Gamma spectrometry of NORM
  3. Analysis of the radioactivity using ED-XRF
 Results and Discussion
  1. Application of analytical methods considering disequilibrium
  2. Assessment of transfer characteristics and the radioactivity distribution in the production cycle of phosphate rock
 Conclusions
 References

저자정보

  • Yoonhee Jung Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, Daejeon, Korea
  • Jong-Myoung Lim Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, Daejeon, Korea
  • Young-Yong Ji Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, Daejeon, Korea
  • Kun Ho Chung Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, Daejeon, Korea
  • Mun Ja Kang Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, Daejeon, Korea

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