Radiological characteristics of CANDU spent fuel stacks using optical fiber probe

The Optical Fiber Probe System (OFPS) was developed for Physical Inventory Verification (PIV) of CANDU spent fuel pool. OFPS is consisted with an optical fiber with scintillator to react just gamma-ray from spent fuels. In this study, a couple of types of scintillation material are evaluated to be appropriate sensor for the physical inventory verification considering detection efficiency, resolution and also cost effectiveness and handling. The peaks from the plastic scintillator (BC-400) are higher compared to those of lithium-7 (Li-7) scintillator due to higher light yields, reduced decay time and larger volume. The sensibility of the plastic scintillators has ability to find hidden peaks between high peaks. BC-400 can be considered appropriate sensor substituting lithium glass scintillator.