A new security strategy for small medium sized reactor (SMR) plants

New methodologies to evaluate the reliability of physical protection in SMRs have been proposed in this study because small-scale facilities would quickly approach undesirable conditions under a small number of threats compared to large-scale systems in which multiple protection systems including security personnel are present. Threats and attacks can be categorized into two types: i) stealth threats and ii) violent and vehicle assaults - the given conditions for each threat are different. In the case of a stealth threat, on-site forces can defeat the threat without outside support. However, on-site forces may not be able to defeat a violent or vehicle assault alone because such threats might be stronger than the on-site forces in terms of the number of people and fire power. Detecting an adversary of stealth threat type could be crucial. However, in the case of a violent or vehicle assault, the time to protect the system should be more significant than the detection of such threats because on-site forces must delay the assault of an adversary until off-site forces arrive. In order to take into account those differences, the probabilities of system failure, which is evaluated by the probability of non-detection times the probability of pathway selection by an adversary, and the consequences of that are selected as critical parameters. For the second threat type, it is reckoned that the expected time for the protection system should be longer than the response time of off-site forces. The expectation of delay time in the system can be computed by the summation of a delay time of a protection system in a certain pathway weighted by the probability of that pathway selection by an adversary. Using these methodologies, the physical protection system could be more effectively established in a small-scale facility.