WASHINGTON -- A vestige of the Cold War may fade into history as government moves forward with plans to close the Tonopah Test Range, a central Nevada proving ground for ballistics and bombing experiments performed for the military and nuclear weapons managers.

Since the mid-1950s, the site about 30 miles south of Tonopah has been a test facility for weapons components developed by the Department of Energy and its predecessors, and artillery experiments conducted for the Pentagon.

What some experts consider the final U.S. atmospheric weapons tests were detonated there in 1962. A crash program tested "bunker busters" for Operation Desert Storm in the early 1990s.

But the federal agency that manages the nation's nuclear weapons complex is pursuing a reorganization and downsizing that includes ceasing operations at the highly instrumented 280-square-mile site adjacent to the Nellis Test and Training Range, according to officials and government documents.

"Just like the Nevada Test Site, it is a part of Cold War history, smaller but no less a part," said Troy Wade of Las Vegas, a former head of defense programs for the Department of Energy.

A shutdown "is significant, but there are other places where one can do the kinds of things that we have done at Tonopah for so many years," Wade said.

National Nuclear Security Administration officials cited budget costs. Figures were not available Thursday.

Thomas D'Agostino, deputy administrator for defense programs for the agency, said much data has been compiled from bomb drops and other Tonopah experiments.

Now, he said, "We don't believe it is necessary to fund a special range for that activity."

The NNSA will study whether the flight testing mission can be transferred to White Sands Missile Range in New Mexico or to the test site.

The plan surprised Nye County leaders.

"This is pretty dismaying to me," County Commissioner Joni Eastley said. "It could have a profound impact on the Tonopah community. There are quite a number of people from Tonopah who work there."

NNSA officials Thursday announced scoping meetings as the agency begins environmental studies for a sprawling reorganization also affecting weapons labs and factories in Tennessee, New Mexico, California, Texas, Missouri and South Carolina.

The reorganization could have other ramifications for Nevada. Over time, more plutonium and enriched uranium likely will be shipped for safekeeping at the Device Assembly Facility, the secured bunker in the interior of the test site.

The NNSA earlier this year completed the movement of roughly 2 tons of special nuclear materials to the test site bunker from the Los Alamos National Laboratory in New Mexico.

Studies also will examine the possible expansion of large scale non-nuclear hydrodynamic and high explosives testing, according to testimony D'Agostino gave to Congress earlier this year.

"We are going to be bringing new mission work there," D'Agostino said Thursday, although officials said details remain to be determined.

Officials haven't said whether that might mean more projects like the Divine Strake non-nuclear explosion that was shelved earlier this year in the wake of pressure from Nevada and Utah leaders and environmental groups.

A meeting on the NNSA reorganization will be held from 11 a.m. to 3 p.m. and from 6 p.m. to 10 p.m. Nov. 28 at the Cashman Center in Las Vegas.

A meeting also is set for 6 p.m. to 10 p.m. Nov. 29 at the Tonopah Convention Center.

Peggy Maze Johnson, director of the Citizen Alert nuclear watchdog group, said the National Nuclear Security Administration has revealed few details of its intentions in Nevada.

"We want to see what they have in mind," Johnson said. "There has been very little except it seems that they want to close down Tonopah."

Under the NNSA's preferred plan, the Tonopah site would close by the end of September 2010.

While the preferred option is to cease operations, NNSA also will look into keeping it open and boosting its resources, said Susan Lacy, environmental compliance officer for the NNSA's Sandia site office in New Mexico.

Lacy said the workforce at Tonopah was 150 to 154 people as of the most recent available count of September 2005. Some commute from Las Vegas.

The government conducted Operation Roller Coaster at the range, the last atmospheric weapons tests before the signing of the Atmospheric Test Ban Treaty in August 1963, said Bill Johnson, director of the Atomic Testing Museum in Las Vegas.

The joint U.S.- United Kingdom undertaking consisted of four detonations in May and June of 1962 that gathered safety data in the event of an accidental explosion.

The high explosive tests were designed to scatter plutonium but not to produce a nuclear reaction, and so were not officially counted as "nuclear tests."

Darwin Morgan, an NNSA spokesman, said cleanup of environmental damage from the test was completed.

According to Sandia National Laboratories, which manages the site, a typical test at Tonopah might involve dropping a bomb body from a plane to check its aerodynamics or the operation of its parachute.

Lacy said the National Nuclear Security Administration would work with the Nevada historic preservation office, "whether it be preserving facilities or photos and drawings. Just what we need to do to preserve the Cold War history."