Detecting weapons grade uranium: give up

Twice in the past 7 years, ABC news has smuggled depleted uranium, with a radioactivity signature comparable to highly enriched uranium (HEU), into the US. Despite packaging and address data designed to ensure maximal screening, the mild radioactivity was not detected.

HEU, like depleted uranium, is just not all that radioactive.

ABC received technical support from two scientists, one of whom was transiently assigned to a Homeland Security watch list as punishment for embarrassing the Bush administration. Last month the two published an article on the detection of smuggled HEU ...

Detecting Nuclear Smuggling: Scientific American

• Existing radiation portal monitors, as well as new advanced spectroscopic portal machines, cannot reliably detect weapons-grade uranium hidden inside shipping containers. They also set off far too many false alarms.
• So-called active detectors might perform better, but they are several years off and are very expensive.
• The U.S. should spend more resources rounding up nuclear smugglers, securing highly enriched uranium that is now scattered overseas, and blending down this material to low-enriched uranium, which cannot be fashioned into a bomb.

In addition to the above synopsis, the author's point out that it's fairly trivial with modern HEU to create a nuclear weapon. (The online version of the article includes a plaintive editor's note claiming all the information in the article is available from public sources.)

The NYT wrote about the detector program last March. The detectors are great at producing false alarms, it turns out that we live in fairly radioactive world*. Problem is, the best research tells us they're really lousy at finding minimally shielded weapons grade uranium.

It's reasonable to invest in better detectors, but the current generation are security theater with a high cost in false alarms. We should be focusing our efforts on restricting leakage of HEU from Russia and other sources. We won't get that kind of intelligent response from Bush or McCain, so all we can hope is that someone else wins the presidency.

On the other hand, I remain puzzled that five years after many experts agreed it was inevitable, we haven't seen nuclear terrorism in the US. It's not the detectors, and most reports indicate we're not doing enough to slow the HEU trade, so what's up?
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* Good thing that current medical research suggests we're more radiation resistant than we thought we were. Our DNA repair systems do relatively well with radiation.