Earticle

초록

영어

Background: It is very difficult to distinguish between a radioactive contamination source and background radiation from natural radionuclides in the marine environment by means of online monitoring system. The objective of this study was to investigate a statistical process for triggering abnormal level of count rate data measured from our on-line seawater radioactivity monitoring. Materials and Methods: Count rate data sets in time series were collected from 9 monitoring posts. All of the count rate data were measured every 15 minutes from the region of interest (ROI) for 137Cs (Eγ = 661.6 keV) on the gamma-ray energy spectrum. The Shewhart (3σ), CUSUM, and Bayesian S-R control chart methods were evaluated and the comparative analysis of determination methods for count rate data was carried out in terms of the false positive incidence rate. All statistical algorithms were developed using R Programming by the authors. Results and Discussion: The 3σ, CUSUM, and S-R analyses resulted in the average false positive incidence rate of 0.164 ±0.047%, 0.064 ±0.0367%, and 0.030 ±0.018%, respectively. The S-R method has a lower value than that of the 3σ and CUSUM method, because the Bayesian S-R method use the information to evaluate a posterior distribution, even though the CUSUM control chart accumulate information from recent data points. As the result of comparison between net count rate and gross count rate measured in time series all the year at a monitoring post using the 3σ control charts, the two methods resulted in the false positive incidence rate of 0.142% and 0.219%, respectively. Conclusion: Bayesian S-R and CUSUM control charts are better suited for on-line seawater radioactivity monitoring with an count rate data in time series than 3σ control chart. However, it requires a continuous increasing trend to differentiate between a false positive and actual radioactive contamination. For the determination of count rate, the net count method is better than the gross count method because of relatively a small variation in the data points.

목차

ABSTRACT
INTRODUCTION
Materials and Methods
1. Count rate data for statistical analysis
2. Statistical control charts
Results and Discussion
1. Comparison of control chart methods
2. Net count rate and gross count rate
Conclusion
References

키워드

저자

• Dong-Myung Lee [ Korea Institute of Nuclear Safety, Daejeon, Korea ] Corresponding Author
• Binh Do Cong [ Vietnam Agency for Radiation and Nuclear Safety, Ha Noi, Vietnam ]
• Jun-Ho Lee [ University of Science and Technology, Daejeon, Korea ]
• In-Young Yeo [ Korea Institute of Nuclear Safety, Daejeon, Korea ]
• Cheol-Su Kim [ Korea Institute of Nuclear Safety, Daejeon, Korea ]

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