Using the VISAC program to calculate the vulnerability of nuclear power plants to terrorism

Nuclear facilities are a vital part of the US infrastructure that also have the potential for serious radiological releases following an incident. The Oak Ridge National Laboratory (ORNL) is currently developing a novel graphical expert system, the Visual Interactive Site Analysis Code (VISAC), to address nuclear facility vulnerability. VISAC must integrate the three concepts of target geometric modelling, damage assessment capabilities, and an event/fault tree methodology similar to that used in the nuclear industry for evaluating accident consequences. VISAC is a Java-based graphical user interface that can analyse a variety of accidents/incidents at nuclear or industrial facilities, ranging from simple component sabotage to an attack with military or terrorist weapons. The list of damaged components from a scenario is then propagated through a set of event/fault trees to determine the overall facility kill probability, the probability of an accompanying radiological release, and the expected facility downtime.