Today there is a post on Port Security.

In the comments section, a discussion about how to prevent a small nuclear [or radiological] device from being brought into the United States via container ship.

What if a small test kit, similar to those used to test for radon in the home, was placed in US bound containers overseas. A container is brought into a port, the test kit analyzed, and a positive reading results in a more thorough search; geiger counters and what-not. Even if a COTS kit applicable for this type of work isn't available now, it could be ready quickly. Maybe three separate strips with each kit, with varying levels of sensitivity.

As IANAE, there will undoubtably be many holes in my proposal. The government would almost certainly eschew $50 detectors in favor of $1,500 detectors, because that's just how the government works.

Secondly, a schmart nuclear terrorist would follow the lead of the failed business-owner-turned-arsonist. If you want to burn down your business, set off a false alarm each night [3am works good] for a week or two. The response of the fire department will slow, and you might even succeed in getting the alarm turned off. Your odds of succeeding -- buring down the business, and destroying most of the evidence -- increases with this reverse boy-who-cried-wolf scnenario. Likewise, months of deliberate false alarms would weaken the program, making it easier to sneak that nuke in.

Also, this would only allow us to find a nuke [or nuke components] hidden in a container after it has reached a US port. This doesn't work if the weapon is to be denonated right there at the port. Components to be shipped separately and assembled later? We could catch it. Functional nuclear bomb with a timer, or triggered by a phone call? We'll probably see the mushroom cloud before we get a chance to check the test kit.

It's not a perfect idea. It would work better in concert with other measures. Inspections at the point of origin, robust intelligence work, and killing the bastards with the capability/desire to ship a nuke across the sea would remain important.

These kits might even work well if they were deployed against a specific overseas terminal, or a specific carrier that was under increased scrutiny.

Just a thought.