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Radionuclide identification based on energy-weighted algorithm and machine learning applied to a multi-array plastic scintillator

  • Hyun Cheol Lee (Korea Institute of Nuclear Nonproliferation and Control) ;
  • Bon Tack Koo (Department of Integrative Medicine Major in Digital Healthcare, Yonsei University College of Medicine) ;
  • Ju Young Jeon (Korea Institute of Nuclear Nonproliferation and Control) ;
  • Bo-Wi Cheon (Department of Radiation Convergence Engineering, Yonsei University) ;
  • Do Hyeon Yoo (Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School) ;
  • Heejun Chung (Korea Institute of Nuclear Nonproliferation and Control) ;
  • Chul Hee Min (Department of Radiation Convergence Engineering, Yonsei University)
  • Received : 2022.12.13
  • Accepted : 2023.07.05
  • Published : 2023.10.25

Abstract

Radiation portal monitors (RPMs) installed at airports and harbors to prevent illicit trafficking of radioactive materials generally use large plastic scintillators. However, their energy resolution is poor and radionuclide identification is nearly unfeasible. In this study, to improve isotope identification, a RPM system based on a multi-array plastic scintillator and convolutional neural network (CNN) was evaluated by measuring the spectra of radioactive sources. A multi-array plastic scintillator comprising an assembly of 14 hexagonal scintillators was fabricated within an area of 50 × 100 cm2. The energy spectra of 137Cs, 60Co, 226Ra, and 4K (KCl) were measured at speeds of 10-30 km/h, respectively, and an energy-weighted algorithm was applied. For the CNN, 700 and 300 spectral images were used as training and testing images, respectively. Compared to the conventional plastic scintillator, the multi-arrayed detector showed a high collection probability of the optical photons generated inside. A Compton maximum peak was observed for four moving radiation sources, and the CNN-based classification results showed that at least 70% was discriminated. Under the speed condition, the spectral fluctuations were higher than those under dwelling condition. However, the machine learning results demonstrated that a considerably high level of nuclide discrimination was possible under source movement conditions.

Keywords

Acknowledgement

This research was supported by the Nuclear Safety Research Program through the Korea Foundation Of Nuclear Safety (KoFONS) using financial resources granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea (No. 2106073).

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