Design Basis Threats and physical protection systems

Design Basis Threats (DBTs) are summarised statements derived from a threat assessment for which a physical protection system (PPS) is planned and designed. This article describes the development of a DBT for the Irradiation Facility at the Centre for Applied Radiation Science and Technology (CARST) in Mafikeng, based on its threat and its risk as a radioactive source. The purpose of the DBT was to serve as a threat assessment technique, providing a basis for planning a PPS by operators of the centre. A competent authority for nuclear security then gives approval for the implementation of the physical protection plan. The DBT assessment methodology is an International Atomic Energy Agency (IAEA) recommended method for designing security measures corresponding to the categories of radioactive sources. The higher the risk, the more secure the facility should be. (author)