Speaker
Description
On-site gamma spectroscopy enables real-time decision-making by measuring radionuclide concentrations without sample extraction, reducing environmental and human-induced errors. While NaI(Tl) scintillators are widely used for field applications, they suffer from poor energy resolution compared to High-Purity Germanium (HPGe) detectors, making isotope identification challenging. To overcome these limitations, LaBr₃(Ce) and CeBr₃ scintillators have been introduced. LaBr₃(Ce) offers superior energy resolution but has a higher intrinsic background due to naturally occurring radioisotopes, whereas CeBr₃ provides slightly lower resolution but reduced intrinsic background. This study evaluates the MDA of NaI(Tl), LaBr₃(Ce), and CeBr₃ to determine their suitability for in situ measurements of liquid radioactive waste.
MDA comparisons were conducted using 1-inch diameter NaI(Tl), LaBr₃(Ce), and CeBr₃ scintillators under identical conditions. Liquid waste samples containing 137Cs and 60Co were collected from KAERI’s research reactor operations. Three samples with varying concentrations were analyzed using a 3600-second measurement time in Marinelli beakers. The gamma-ray spectra were processed with Genie 2000 software, employing the Currie MDA method. Background measurements were taken for 600 seconds, and MDAs were calculated for energy levels of 661.7 keV, 1173 keV, and 1332 keV.
Across all samples and energy levels, LaBr₃(Ce) exhibited the lowest MDA, followed by CeBr₃, while NaI(Tl) consistently had the highest MDA, indicating lower detection sensitivity. Despite LaBr₃(Ce)’s higher intrinsic background, its superior energy resolution resulted in the best performance. CeBr₃ provided stable detection performance with lower intrinsic background, making it a viable alternative. In contrast, NaI(Tl)’s poor energy resolution hindered its ability to detect low-activity radionuclides effectively.
The study confirms that LaBr₃(Ce) is the most suitable scintillator for on-site liquid radioactive waste assessment due to its superior energy resolution and lowest MDA. CeBr₃ also demonstrated reliable performance with a lower intrinsic background. NaI(Tl), despite being widely used, showed the highest MDA, making it less effective for low-activity measurements. These findings highlight the importance of selecting appropriate scintillator materials to optimize field-based radiation monitoring.
| Workshop topics | Detector systems |
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