Inside the Pentagon


REPORT: SPONTANEOUS COMBUSTION OF CHEMICAL WEAPONS UNLIKELY

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Date: February 26, 2004

The likelihood of U.S. chemical weapon stockpiles spontaneously
combusting is very low, according to a National Academies of Sciences
report released this month.

The risk of autocatalytic explosion is often cited as a prime reason for
accelerating the destruction of chemical weapons by incineration.

Aging stockpiles of U.S. chemical weapons are vulnerable to internal
gaseous reactions that could lead to sudden explosions, but the
worst-case possibility of such an event occurring by 2010 is nine in 100
trillion, the report states.

A chemical stabilizing agent inside 40-year-old M55 rockets containing
sarin is meant to prevent the nerve gas from reacting with the aluminum
alloy warhead. Sometimes the stabilizer fails to prevent sarin from
corroding the metal, leading to the danger that sarin could react with
the rocket's propellant, causing a spontaneous explosion.

"You've got a better chance of a Metro train derailing and hitting you
on the platform," responded Craig Williams, director of the
Kentucky-based Chemical Weapons Working Group, a watchdog organization
that advocates non-incineration destruction.

The NAS report indicates "that the rhetoric used by the Army that these
particular rockets pose such a risk to the community" has been
exaggerated, Williams said Feb. 24. "The risk, although there -- and we
want to get rid of that risk -- is very small," he said, suggesting the
Army, which is executive agent for the chemical demilitarization
program, focus more on its alternative disposal programs.

The report states the risk of stabilizer degradation at the chemical
weapon depot in Anniston, AL -- where the majority of the remaining M55
rockets are kept -- "is less than 0.1 percent of the total assessed risk
from disposal operations," and "much less than 0.1 percent of the total
risk of storage."

But, autocatalysis is characterized by a slow induction rate followed by
a rapid acceleration. "There is a possibility that the rapidly rising
portion of the curve . . . is being approached," the report states.

Also, preventive measures taken by the Army to isolate leaky chemical
rockets actually increase the risk of spontaneous explosion. A corroding
M55 rocket is "overpackedâ"-- that is, encased in a new airtight
container, according to the NAS. But overpacking prevents heat inside
the rocket from dissipating, increasing the rate of stabilizer agent
degradation. Some leaky rockets "have been overpacked several times,"
the report states. Internal leaks are impossible to detect without
dismantling the rocket.

Since 1973, the Army has checked regularly for external gas leaks, the
report finds. Through June 2002, 4,789 chemical weapons of all varieties
had been found leaking. The vast majority of those were sarin munitions.
The report advises the Army to begin continuous temperature monitoring
of storage facilities.

The report also finds the stabilizing agent for VX nerve agent munitions
"may be dropping to critical levels." In addition, pressurized hydrogen
gas has formed in some mustard agent weapons, presenting a "significant
risk" of explosion to workers during disposal operations.

-- David Perera