Evaluation of Reinforcement Most Vulnerable Path to Enhance Physical Protection System for Radioactive Sources in Universitas Gadjah Mada’s Nuclear Engineering Department Using a Stochastic Approach

The increasing threat of the misuse of radioactive sources underscores the importance of nuclear security. To prevent physical threats, nuclear security relies on an effective Physical Protection System (PPS). The Department of Nuclear Engineering and Engineering Physics, Faculty of Engineering, Universitas Gadjah Mada (DTNTF FT UGM) as an educational institution uses radioactive sources for educational and research purposes. However, there are multiple paths leading to the radioactive source storage facility, making the radioactive sources vulnerable to theft. This study aims to evaluate the Most Vulnerable Path (MVP) toward the radioactive source storage facility at DTNTF FT UGM using a stochastic approach based on the Estimate of Adversary Sequence Interruption (EASI) model and Adversary Sequence Diagram (ASD). As a result, the second path is identified as the MVP with the lowest probability of interruption (PI). The enhancement of the PPS by adding physical protection elements for the second path has theoretically proven to be reliable. The PI value significantly increases by 33.18%, thereby improving PPS effectiveness. This study emphasizes the importance of periodic evaluation and optimization of PPS to mitigate threats to nuclear materials in any sector.