Multi-State Modeling in ASSESS

The Analytic System and Software for Evaluating Safeguards and Security (ASSESS) is an integrated safeguards evaluation tool focusing on theft and diversion of special nuclear material (SNM) by insiders, outsiders, and collusion between insiders and outsiders. ASSESS features a common Facility Description module that allows for defining a facility's safeguards and security system simultaneously for both insider and outsider threats. This Facility Description module supports defining safeguards during two states. The two states could represent \"day\" and \"night,\" or \"normal\" and \"emergency,\" or simply \"open\" and \"closed.\" A problem arises due to differences in the modi operandi of (and hence, evaluation approaches for) insider and outsider threats. This can lead to situations where it is impossible to simultaneously define states correctly to meet the needs of both the Insider and Outsider evaluation modules. We have developed and are currently implementing an approach to address this problem. This approach has required programming in four ASSESS modules. In this paper, we discuss the ASSESS state problem and give an overview of the solution, including the implementation in the Facility and Insider modules. A second paper discussing details of the implementation in the Outsider module is also being presented in this session.