Detecting nuclear weapons

From: John Clark (
Date: Thu Nov 01 2001 - 11:29:40 MST

It's from a Time magazine a few years old but I found some interesting stuff about
NEST, a sort of high tech SWAT team that detects nuclear weapons:

Helicopters equipped with radiation detectors can sweep over a city but a nuclear
weapon gives off little telltale radiation and is nearly impossible to find from above
a dense, urban area. Most of the search must be conducted on the ground. Minivans
are rented at the local airport, the backseats removed and replaced with electronic
detectors that can sniff the neutrons and gamma radiation a nuclear device might emit.
The vans, however, are only good for use in large open areas like parking lots and highways.
To search narrow streets and buildings, as many as 100 two-person teams, dressed as
inconspicuously as possible, are sent on foot patrols. One team member carries a special
radiation detector designed to be hidden in briefcases, student backpacks, laptop computer
bags--even beer coolers, in the case of a threat to vaporize the Super Bowl.

One of the searchers, "Becky" (she asked that her real name not be used), described how
she made her rounds on a recent training exercise in a large city. A 31-year-old Energy
Department employee who began training as a nest searcher seven years ago, Becky and
10 colleagues were assigned to hunt for a simulated nuclear device in a hotel with 32 floors
and 2,052 rooms.

Walking down the corridors, Becky and her male partner looked like the typical tourist
couple on vacation, dressed in Bermuda shorts and T shirts, cameras slung over their
necks. But hidden in Becky's suitcase was a sophisticated sodium iodide crystal detector
to sniff minute amounts of gamma radiation from as far away as another room. Halfway
down a corridor, Becky suddenly heard "the voice," an irritating robotic message transmitted
from the suitcase to a wireless, button-sized beige receiver in her ear. "Gamma alarm four,"
the voice droned. That was a strong radiation signal. She glanced left at the room number on
the next door and subtracted three from it. The detector's microcomputer takes several
seconds to analyze the radiation and calculate its strength, so the room three doors behind
her must have been the one actually giving off gamma rays. Becky and her partner never
turned around or slowed their pace, lest they attract attention from other guests. At the end
of the corridor, they looked back nonchalantly, then ducked into the stairwell. Becky pulled
out a small radio from her purse. "We have a hit," she whispered, and relayed the room number.
The searchers had found the simulated nuclear device, which had been emitting a harmless
amount of radiation, in less than two hours.

As if the searching weren't nerve-racking enough, operating the detectors requires great skill
because the instruments, sensitive enough to home in on a bomb, can be confused by the
soup of a metropolis' naturally occurring radiation. Freshly paved roads, yellow rest-room tiles,
the Vermont granite used in some of Washington's federal buildings, a patient walking out of a
hospital after radiation therapy, even a bunch of bananas can set off the detectors. Finding a
nuclear bomb in a city, according to a searcher, "is like looking for a needle in a haystack of needles."

John K Clark

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