Development of Compton imaging system for nuclear material monitoring at pyroprocessing test-bed facility

The Korea Atomic Energy Research Institute (KAERI) has constructed a test-bed facility, named PRIDE (PyRoprocess Integrated inactive DEmonstration), for demonstration of pyroprocessing technology. Even though the PRIDE facility utilizes depleted uranium, instead of actual spent fuel, as process material, it will play an important role not only from the process perspective, but also from the safeguards standpoint. In the present study, a Compton imaging system based on pixelated GAGG:Ce scintillation detectors was constructed and tested to determine its utility for accurate imaging of nuclear material locations and, thus, its applicability as a safeguards monitoring system at the PRIDE facility. In a lab-scale performance evaluation, when the dose rate induced by a Cs-137 point-like source was approximate to 0.1 Sv/h, the source location was imaged within 5 min. The image resolutions were 22 degrees and 7.6 degrees for real-time monitoring using a back-projection algorithm and for near-real-time monitoring using a statistical iterative algorithm, respectively. The developed Compton imaging system was finally applied to low-enriched uranium and also to depleted uranium, which latter is the process material of the PRIDE facility, and it was indicated that the Compton imaging system can localize nuclear materials within a few minutes under conditions similar to those prevailing at the PRIDE facility. The results of this study show that the Compton imaging system, and Compton imaging technology in general, has a great potential for utilization as a nuclear material monitoring tool at the PRIDE facility.Ministry of Science, ICT and Future Planning 15ZC1810, NRF-2012M2A8A5025950, NRF-2015M2A2A6A01045241, NRF-2015M2C3A1028968