Tuesday, December 19, 2006

America's Chernobyl Waiting to Happen

"Dallas, Texas, Mar. 30, 2005 (AP) --- An apparent nuclear explosion in Amarillo, Texas has cut off all communications with the West Texas city and regions in a fifteen-mile radius around the blast. Eyewitness accounts by airline pilots in the vicinity report an 'incredible flash' followed by a mushroom cloud reaching at least 35,000 feet. Speculation on the source of the explosion has centered on Amarillo's Pantex plant, the nation's only facility for construction and disassembly of nuclear weapons."

In case you think you missed something a year ago last March, the news item above is fiction. But according to some sources, it is plausible. It could have happened. And there is reason to believe that unless some serious housecleaning takes place in Amarillo, the chances that something like this might happen in the future are higher than any of us would like.

The end of the Cold War brought hopes that instead of piling up megaton after megaton
of mutually assured destructive power in the shape of thermonuclear weapons, the U. S. and the Soviet Union (or what was left of it) would begin to disassemble their nuclear stockpiles to make the world a safer place. Over the past fifteen years, international agreements have been reached to do exactly that. From a peak of over 30,000 nuclear warheads in 1965, the U. S. stockpile has declined to just a little over 10,000 as of 2002. And here is where the engineering issues come in, because for every downtick of that number, somebody somewhere has to disassemble a nuclear warhead.

A nuclear bomb or missile is not something that you just throw on the surplus market to dispose of. First it has to be rendered incapable of exploding. Then the plutonium and other dangerous explosive materials have to be removed in a way that is both safe to the technicians doing the work, and also to the surrounding countryside and population. As you might imagine, these operations are difficult, dangerous, and require secret specialized knowledge. For more than thirty years, the only facility in the U. S. where nuclear weapons were made or disassembled has been the Pantex plant outside Amarillo, Texas. It is currently operated by a consortium of private contractors including BWXT, Honeywell, and Bechtel, and works exclusively for the federal government, specifically the Department of Energy. If you want a nuclear weapon taken apart, you go to Pantex, period. And therein lies a potential problem.

Where I teach engineering, the job of nuclear weapon disassembler is not one that comes up a lot when students tell me what they'd like to be when they graduate. I imagine that it is hard to recruit and retain people who are both willing and qualified to do such work. But at the same time, it is not the kind of growth industry that attracts a lot of investment. So it is plausible to me that as the demand for disassembly increases, the corporate bosses in charge of the operation might tend to skimp on things like deferred maintenance, safety training and execution, and hiring of additional staff. That is the picture which emerges from an anonymous letter made public recently by the Project on Government Oversight, a government watchdog group.

Anonymous letters can contain exaggerations, but what is not in dispute is the fact that on three occasions beginning Mar. 30, 2005, someone at Pantex tried to disassemble a nuclear weapon in a way that set off all kinds of alarms in the minds of experts who know the details. I'm speculating at this point, but as I read between the lines and use my knowledge of 1965-era technology, something like this may have happened.

A nuclear weapon built in 1965 probably contained no computers, relatively few transistors, and a good many vacuum tubes. Any safety interlocks to prevent accidental detonation were probably mechanical as well as electronic, and consisted of switches, relays, and possibly some rudimentary transistor circuits. But somewhere physically inside the long cylindrical structure lies a terminal which, if contacted by a grounded piece of metal, will probably set the whole thing off and vaporize Amarillo and the surrounding area.

A piece of equipment that has been sitting around since 1965 in a cold, drafty missile silo is probably a little corroded here and there. Screws and plugs that used to come apart easily are now stubborn or even frozen in place. The technician in charge of beginning disassembly of this baby probably tried all the standard approaches to unscrewing a vital part in order to disable it, without success. At that point, desperation overcame judgment. The official news release from the National Nuclear Safety Agency puts it in bureaucratese thus: "This includes the failures to adhere to limits in the force applied to the weapon assembly and a Technical Safety Requirement violation associated with the use of a tool that was explicitly forbidden from use as stated in a Justification for Continued Operation." Maybe he whammed at it with a big hammer. Maybe he tried drilling out a stuck bolt with an electric drill. We may never know. But what we do know is, the reasons for all these Technical Safety Requirements is that if you violate them, you edge closer to setting off an explosion of some kind.

Not every explosion that could happen at Pantex would be The Big One with the mushroom cloud and a megaton of energy. The way nuclear weapons work is by using cleverly designed pieces of conventional high explosive to create configurations that favor the initiation of the nuclear chain reactions that produce the big boom. A lot of things have to go right (or wrong, depending on your point of view) in order for a full-scale nuclear explosion to happen. Kim Jong Il of North Korea found this out not too long ago when his nuclear test fizzled rather than boomed. But even if nothing nuclear happens when the conventional explosives go off, you've got a fine mess on your hands: probably a few people killed, expensive secret equipment destroyed, and worst from an environmental viewpoint, plutonium or other hazardous nuclear material spread all over the place, including the atmosphere.

This general sort of thing was what happened at Chernobyl, Ukraine in 1986, when some technicians experimenting late at night with a badly designed nuclear power plant managed to blow it up. The bald-faced coverup that the USSR tried to mount in the disaster's aftermath may have contributed to its ultimate downfall. So even if the worst-case scenario of a nuclear explosion doesn't ever happen at Pantex, a "small" explosion of conventional weapons could cause a release of nuclear material that could harm thousands or millions of people downwind. Where I happen to live, incidentally.

I hope the concerns pointed out by the Pantex employees who apparently wrote the anonymous letter are exaggerated. I hope that the statement from Pantex's official website that "[t]here is no credible scenario at Pantex in which an accident can result in a nuclear detonation" is true. But incredible things do happen from time to time. Let's just hope they don't happen at Pantex any time soon.

Sources: The Project on Government Oversight webpage citing the Pantex employees' anonymous letter is at http://www.pogo.org/p/homeland/hl-061201-bodman.html. The official Pantex website statement about a nuclear explosion not being a credible scenario is at http://www.pantex.com/currentnews/factSheets.html. Statistics on the U. S. nuclear weapons stockpile are from Wikipedia's article on "United States and weapons of mass destruction."

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