The Tile-map Based Vulnerability Assessment Code of a Physical Protection System: SAPE (Systematic Analysis of Protection Effectiveness)

摘要

Nuclear facilities have a robust physical protection system (PPS) due to the potential threat of terrorism. A PPS includes detectors, door locks, fences, regular guard patrols, and a nearby military force. In order to fully operate a PPS, regular vulnerability assessments are essential. Evaluating the PPS of a nuclear facility is a complicated process; hence several computer codes (EASI and SAVI) have been developed to assess a PPS. Existing codes, however, have limitations in representing the position of a facility because they use a simplified model of a PPS - called the adversary sequence diagram (ASD). We suggest an intuitive and accurate vulnerability assessment code using a tile-map. Unlike an adversary sequence diagram, a tile-map provides a bird-eye view of a PPS, and thus an adversary's path is easier to understand. A tile-map also realistically represents relative positions between elements. For instance, it can reflect the decrease in detection probability of a passive infra-red sensor as the distance from the sensor is increased. We call this vulnerability assessment code, based on a tile-map, a systematic analysis of protection effectiveness (SAPE). The SAPE computer code finds the most vulnerable path of a tile-map as a measure of effectiveness. The SAPE code uses well known heuristic search algorithm to find the weakest path and calculates the probability of interruption. The SAPE also makes a sensitivity analysis of protection elements that are placed on the most vulnerable path. The sensitivity analysis will provide a guide for an efficient upgrade of a physical protection system.