Development of a phoswich detector for alpha, beta, and gamma-ray emitting radionuclide identification for decommissioning

Tateishi, Dai; Terasaka, Yuta   ; Morishita, Yuki   ; Sato, Yuki  

To ensure the safe decommissioning of the Fukushima Daiichi Nuclear Power Station, we developed a spectrum analysis method for the phoswich detector that can identify alpha-, beta-, and gamma-ray-emitting radionuclides, even in the presence of high gamma-ray backgrounds. The detector uses ZnS(Ag) and plastic scintillators to distinguish radionuclides by energy spectrum analysis. Tests with Am, Sr, Co, Cs (), Cs () revealed distinct spectral shapes and slopes, facilitating successful radionuclide identification of Am, Sr, Cs (),and Cs (). However, we found no observable difference in the energy spectral shapes between Co and Cs gamma-ray emissions, which limited our spectral analysis method's ability to distinguish between these two radionuclides. This method improves upon previous smear-based techniques by detecting fixed contamination and differentiating between beta and gamma sources. The approach holds promise for applications in the characterization and treatment of radioactive waste.