Network deployment of radiation detectors with physics-based detection probability calculations

Abstract

We describe a model for deploying radiation detectors on a transportation network consisting of two adversaries: a nuclear-material smuggler and an interdictor. The interdictor first installs the detectors. These installations are transparent to the smuggler, and are made under an uncertain threat scenario, which specifies the smuggler's origin and destination, the nature of the material being smuggled, the manner in which it is shielded, and the mechanism by which the smuggler selects a route. The interdictor's goal is to minimize the probability the smuggler evades detection. The performance of the detection equipment depends on the material being sensed, geometric attenuation, shielding, cargo and container type, background, time allotted for sensing and a number of other factors. Using a stochastic radiation transport code (MCNPX), we estimate detection probabilities for a specific set of such parameters, and inform the interdiction model with these estimates.

Interdiction Models and Applications

“…The development of this model began as part of the DOE's Second Line of Defense Program [45,55] and later was coupled with physics-based estimates of detection probabilities and adapted for U.S. ports of entry [22]. The model we review here is the simplest of a family of models that has been developed.…”

“…While there are an enormous number of factors that affect the detection probability of an RPM, under mild assumptions, we can aggregate many of these and achieve an equivalent model [22]. This significantly reduces model complexity.…”

“…Additional, geographic structure of optimal solutions to model (12) exists as we parametrically range the budget, b [22]. In particular, as the budget grows, the checkpoints that receive detectors fall in geographic clusters.…”

Network routing for insurgency: An adversarial risk analysis framework

“…Traditional game theorists have treated somewhat similar games. Normal form network interdiction games have been studied by Dimitrov et al [10], Bayrak and Bailey [4], and Washburn and Wood [39], although these article make somewhat different assumptions and have different payoff criteria. Extensive form games, in which the route or the IED placement or both are decided adaptively, have been studied by Guttfraind, Hagberg and Pan [14], Israeli and Wood [20], and arise generally in Ref.…”

Rethinking the encounter probability for direct-to-target nuclear attacks for aviation security

“…A weapon can be transported in a cargo container, in a small vessel, on a general aviation aircraft, on a train, or on a large cargo ship, for example. Much research has focused on screening for nuclear material in cargo containers at domestic and foreign ports and at land border crossings (Wein et al 2007;Dimitrov et al 2011;McLay et al 2011).…”