A new physical protection measure for evaluating risks at nuclear facilities

Abstract

The Physical Protection (PP) measures for evaluating risks at nuclear facilities have been developed. The developed measures can be used to not only evaluate the physical protection status of operational nuclear facilities, but also for the next generation of nuclear systems such as the SFR (Sodium Fast Reactor) and the VHTR (Very High Temperature Reactor). These measures can substitute those existing methodologies developed by the Gen-IV PR&PP group and the INPRO. These measures have been adapted to hypothetical nuclear facilities, and scenarios have been created to analyze PP risk quantitatively. The PP measures developed in this study contain Probability of Interruption (PI), Probability of Neutralization (PN), Consequences (C), Fissile Material Type (MT) and Effectiveness of Physical Protection Resources (EPR). In this paper, tools and tables for calculating each PP measure are suggested and illustrated in detail. The PI and PN measures can be calculated quantitatively using these tools. A new computer code for calculating PI has also been developed. The EPR, MT and C measures were obtained from tables developed by collecting and analyzing related information. Computational results of the PP measures in five different scenarios, and at three different facilities demonstrate the effectiveness of the methodology developed. The results obtained are represented in a spider diagram (after normalizing the measure calculated). The value of PI and C changed because of the scenario; but the other three measures, EPR, MT and PN (determined by the characteristics of the facility) did not vary. It is expected that by using a larger number of refined scenarios more reliable information will be provided. It is also anticipated that the PP measures developed in this study can be applied to operational nuclear facilities, as well as a future nuclear systems under development.