The design of a physical protection system for the 444TBq ⁶⁰Co Irradiation Source at the centre for applied radiation science and technology, Mafikeng, South Africa

Abstract

The accelerated technological change experienced by the world at the outset of the twenty-first century including technologies used in the nuclear field can pose serious risks to public health, property and the environment if not controlled and handled appropriately. Nuclear and other radioactive materials are being used in a growing variety of settings to advance development in most Countries. In total there are approximately 17,500 registered radioactive sources in South Africa and these sources need to be protected against adversaries coupled with several cases of infiltration of the Pelindaba nuclear research facility outside Pretoria means there should be a robust nuclear security regime put in place. This study designed a physical protection system (PPS) for the ⁶⁰Co irradiation source which will be used at the Centre for Applied Radiation Science and Technology (CARST) of the North-West University (Mafikeng Campus). The PPS effectiveness was analyzed and evaluated quantitatively by the use of the Estimate of Adversary Sequence Interruption (EASI) code and the Estimation of Adversary Sequence Interruption for Multiple Pathways (EASIM) code. These evaluations were done to calculate the Probability of effectiveness (PE from the Probability of Interruption (PI and the Probability of Neutralization (PN of a potential adversary attack scenario along a specific path for the EASI code and along multiple pathways simultaneously for the EASIM code. The PE values show the extent to which the security system is effective.

Results obtained from this study indicated low values of PE for the existing protection system and high values of PE for the proposed physical protection system design. This increase in the PE value indicates a potentially higher overall level of security for the proposed PPS of the center consisting of three buildings namely F2C, F2A and F2E. The effectiveness of the proposed PPS for the proposed paths increased from zero (0) to a minimum of 0.50 and a maximum of 0.80 for sabotage scenario of F2C and a minimum of 0.50 and a maximum of 0.85 for theft scenario of F2C, F2A and F2E using the EASI evaluation code. The EASIM code’s results increased from zero (0) to a minimum of 0.55 and a maximum of 0.69 for sabotage scenario of F2C and a minimum of 0.54 to a maximum of 0.80 for theft scenario of F2C, F2A and F2E, thus indicating an increased level of overall effectiveness for the proposed PPS.