Detecting nukes in transit: What can the newly-established DNDO do?

Just finished writing a paper with Sri and Tom Tisch - it's titled 'Nuclear Detection: Portals, fixed detectors, and NEST teams won't work on a national scale, so what's next?'. We analyze the *use* of nuclear detectors to help prevent terrorist nuclear attacks, and we conclude that fixed detector approaches (such as those currently being implemented) are unlikely to be that effective. Here's the executive summary of the paper:

Recognizing the need for detecting terrorist attempts to transport or use fissile nuclear materials, President Bush’s FY 2006 budget request includes $246 million to form a Domestic Nuclear Detection Office (DNDO) within the Department of Homeland Security (DHS). [1] “The DNDO will provide a single accountable organization with dedicated responsibilities to develop the global nuclear detection architecture, and acquire, and support the deployment of the domestic detection system…” [2] How can DNDO planners deliver a global nuclear detection architecture that works?

Nuclear detection systems, as architected and deployed today, leave loopholes in the transportation network that terrorists can easily exploit by making use of light road vehicles to private jets to oil tankers [3].  Progress can be made if we face up to three fundamental facts:

1. Terrorists will most likely try to use highly enriched uranium (HEU), not plutonium: assembly of a HEU bomb does not involve technically complex detonation as with a plutonium bomb.

2. Terrorists can circumvent a network of fixed detectors: fixed detectors not only lack sufficient proximity and exposure to the vehicle in transit but also do not screen many types of vehicles.

3. R&D breakthroughs cannot change the physics of detection: passive detection of HEU will always be limited by its natural rate of radioactivity, and the attenuation of radioactivity is very sharp with distance [4]. The gamma rays and neutrons useful for detecting shielded HEU permit detection only at short distances (2-4 feet or less) and require that there is sufficient time to count a sufficient number of particles (several minutes to hours).

Recommendation: Due to fundamental physical limits, the current trend toward a fixed detector infrastructure is a dead-end. The only way shielded HEU can be effectively detected is if commercially-available detector technology, rather than being kept at fixed locations, are directly integrated into vehicles themselves. Detectors would travel with vehicles and have enough time to record radioactivity before reporting their readings to a network of check-points (in the same way E-Z pass collects highway tolls).

Our paper, 'Nuclear Detection: Portals, fixed detectors, and NEST teams won't work on a national scale, so what's next?' explores tradeoffs in detecting HEU in transit, and analyzes its technical, operational, and economic feasibility.

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[1] “R&D in the Department of Homeland Security”, AAAS, http://www.aaas.org/spp/rd/06pch12.htm

[2] “Fact Sheet: Domestic Nuclear Detection Office,” http://www.dhs.gov/dhspublic/display?content=4474

[3] Medalia, J., 2005, “Nuclear Terrorism: A Brief Review of Threats and Responses,” CRS Report for Congress, The Library of Congress http://fpc.state.gov/documents/organization/43399.pdf

[4] attenuation of radioactivity with distance is subject to an inverse-square law in free-space and is exponential with shielding