CASE STUDY ON PHYSICAL SECURITY ASSESSMENT OF A CATEGORY 1 GAMMA IRRADIATION FACILITY

Analysis and evaluation of a physical protection system (PPS) design begin with a review and thorough understanding of the protection objectives of the system. A physical protection system is deployed to prevent or mitigate loss of valuable assets (e.g., property or life). It consists of three important elements: detection, delay, and response. In our study, the asset is the Category I radioactive sources, which have high activity and need to have high security system to secure them. In Thailand, the Category 1 source facility is required to have effective PPS to protect people and environment from radiological hazards. This study focuses on the evaluation of a physical protection system of a Category 1 gamma source facility in Thailand against several potential cases of outsider intrusion, using the EASY model to calculate the probability of interruption (PI). The study includes 4 parts: collect data to determine system objectives, evaluate the collected data for the current design, design additional PPS, and analyze result and recommendation. Based on the current PPS design and the design basis threat data, there are 6 potential attack scenarios to evaluate the PPS against. Each consists of three modes of transportation potentially used by the adversary: running, motorcycle, truck. The result shows that the PI in several scenarios is in the range of 0.50-0.75, which is considered “too low” and something should be done to improve the PPS. After improving the PPS by installing a steel cage at the laboratory room door to increase delay, the PI for all scenarios is increased to above 0.90, meaning that the security system effectiveness is high.