Hush-Hush Bomb Plant Chills Out : Texans get first look at ‘gravel gerties’ and ‘igloos’ as nuclear weapons come back for storage.

For the better part of four decades, everybody in the Texas Panhandle has known what was going on behind the razor wire fences out on Farm to Market Road 2373 east of Amarillo.

And some polls showed that 82% of the people hereabouts approved of it--which is not to say that they had any choice.

What was going on at the government’s Pantex plant from the 1950s through the ‘80s was the assembly of nuclear weapons--cigar-shaped gravity bombs with the wallop of a million tons of TNT, sleek models to be carried by cruise missiles, little fellas to be fired out of artillery pieces. Not much was said about it. The work went on as methodically as the nearby grain elevators were filled and steers were sent off to market.

An unmarked train loaded with warheads used to rumble away from the place occasionally, and year in and year out, tractor trailer rigs with bulletproof glass and government license plates were escorted out--on their way to the Dakotas, to a submarine base in Washington, or an air base in Nebraska.

The government still won’t say how many bombs have been put together at Pantex, but the number runs well into the tens of thousands, because it is now acknowledged that 50,000 later have been brought back and taken apart. And they were replaced by smaller, more modern, more lethal models.

Some 40 years after Pantex (which comes from the words Panhandle and Texas) sent its first hydrogen bomb to the Air Force, the United States has 30-odd different nuclear warheads in service.

But that figure is coming down--by the turn of the century, the number of warhead models is expected to be somewhere between five and 10.

Pantex is no longer assembling new bombs. But that does not mean business is drying up.

To the contrary. The 3,000 employees in the 16,000-acre complex are now heavily into the business of disassembling the weapons they have put together over the years.

Besides continuing to take apart and inspect randomly selected warheads still in the nuclear stockpile, they are retiring weapons at the rate of 2,000 per year, staying ahead of the goal the Energy Department and the Pentagon have set for them.

Working inside “Gravel Gerties,” steel and concrete structures hulled out of the ground and overlain by 17 feet of sand and gravel, technicians separate the guidance and triggering mechanisms from the “physics package” containing plutonium and/or uranium fuel and the high-energy conventional explosives that set them off.

Precious metals, such as gold, are saved. Some top-secret non-nuclear components are smashed, others carefully saved to be stored at still-secret repositories.

The nuclear materials are moved into “igloos,” bunkers covered with dirt, sealed with massive doors blocked by 5-ton slabs of concrete.

Sixty such bunkers provide temporary storage for weapons brought to Pantex for inspection, as they have in the past for those awaiting shipment to customers like the Strategic Air Command or to U.S. weapons depots in Germany.

They may also provide storage for six to 10 years or more for the weapons’ plutonium “pits,” or triggers.

In weapons, the hollow spheres of plutonium are filled with tritium and surrounded by high-energy conventional explosives that compress the sphere into a critical mass, triggering a thermonuclear explosion.

These cores present the most difficult problem in dismantling the thousands of weapons that will now be taken down as a result of arms accords ending the Cold War.

In the past, the plutonium components from dismantled weapons were sent back to the Rocky Flats weapons plant outside Denver where they were fabricated. But now, Rocky Flats is out of the weapons production business. Its only mission is to clean up massive pollution from its years of manufacturing triggers for thermonuclear warheads.

Pantex has just enough space to store these triggers until next summer at the present rate of disassembly. Unless it can get a go-ahead to stack them layer upon layer, the government will have a choice of either finding additional interim--six to 10 years--storage space or suspending the dismantling of warheads.

The issue has been presented to Texas environmental authorities for consideration before federal officials render a decision next summer.

Reflecting the depth of the change that has lately gone on behind the Pantex fences, officials of the Energy Department and Mason & Hangar-Silas Mason Co., the contractor that has long operated the complex, Wednesday, for the first time, escorted reporters through the plant.

They also have offered the public the opportunity to take a similar driving tour of the premises.

This opportunity to see life behind the razor wire fences seemed to strike a chord: Within days of the announcement of the public tours, all available space was spoken for through next June.