Gerald Talbot listens to a question Thursday in his North Las Vegas office about the challenges he faces as the new manager of the National Nuclear Security Administration's Nevada Site Office. Photo by John Locher.

With a retired Navy rear admiral now charting the course for the Nevada Test Site, historians will look back at the first months of Gerald L. Talbot's turn at the wheel and see he navigated through a non-nuclear blast that was canceled, continued the quest for a reliable Trident submarine warhead and launched a new era for checking the integrity of plutonium in the stockpile.

From his office in North Las Vegas looking out at the tower where California's Lawrence Livermore National Laboratory once built diagnostic canisters for full-scale nuclear weapons tests, the 59-year-old Talbot, himself an engineer, pondered the prospects last week for what scientists are calling the "Thermos" experiments.

They are so small compared even to subcritical experiments that they can be conducted, as their name implies, in a vessel the size of a coffee thermos.

"I would say we have a number of experiments of varying magnitude that we will conduct," Talbot said Thursday.

At the time, scientists from the nuclear weapons lab in Los Alamos, N.M., were busy conducting Thermos-5 experiments in an underground chamber at the test site, 85 miles northwest of Las Vegas.

Subcritical experiments involve small amounts of nuclear materials and are designed to stop short of triggering nuclear chain reactions. They allow scientists to study how materials, such as plutonium, blow apart when detonated by explosives.

Thermos experiments are similar but smaller. They involve gram-size amounts of plutonium and are designed to produce data on temperatures and pressures instead of data about geometrical changes a chunk of aging plutonium undergoes when shocked by high explosives in a subcritical experiment.

Talbot said Thermos experiments let scientists explore what happens with plutonium immediately after it is detonated.

"There is no nuclear yield out of this. So, we're trying to determine what the material properties of plutonium are at higher temperatures and pressures," he said.

Darwin Morgan, spokesman for the National Nuclear Security Administration, said Thermos-5, the fourth in a series, was conducted Thursday. The first, Thermos-2, was set off Feb. 7.

Thermos-1 was damaged in transport from the Los Alamos lab, he said, explaining the difference in the numbering.

Talbot, a career nuclear Navy sailor, took over as manager of the National Nuclear Security Administration's Nevada Site Office on Dec. 11 while in Washington, D.C., and arrived for his first day at the North Las Vegas office on Jan. 8. He replaced Kathy A. Carlson, who retired as manager in May 2006.

Talbot on Thursday discussed the challenges of his new job overseeing the test site's $400 million budget and more than 125 federal employees, backed by 2,500 contractor personnel.

Only a week before, news that the Lawrence Livermore lab's design for the Reliable Replacement Warhead had been chosen over one by the Los Alamos lab made national headlines. Weighing heavily in the NNSA's decision was that the Livermore design required no full-scale testing.

Talbot said the design eventually will lead to development and production of the RRW-1, a single nuclear bomb, or "physics package," that will be delivered by D-5 missile systems on the nation's 14 Trident submarines.

The D-5 is an intercontinental, submarine-launched ballistic missile with a range of more than 4,000 miles.

"Since we eliminated testing as part of the test ban treaty back when we did our last test in September of 1992, we have accumulated a tremendous amount of science and understanding about the systems, not only the physics package but all the supporting infrastructure associated with that delivery system," Talbot said.

"That has provided for us the level of confidence and understanding of how to manufacture a nuclear weapon that doesn't require confirmatory testing.

"I think that is a real vote of confidence for the science program and the experimental program ... to make it very clear that we are actually not going to test RRW in its production cycle," he said.

Meanwhile, he said, work using the test site's high-tech physics tools and subcritical experiments will continue to ensure that the stockpile is safe and reliable.

"But the Nevada Test Site has a very diverse outlook," Talbot said. "The global war on terrorism and supporting homeland security is a tremendous amount of work that is uniquely done only at the Nevada Test Site."

He was referring to one project aimed at detecting nuclear material, say for a so-called dirty bomb, that a terrorist might try to sneak into the country.

"Homeland Security has made a very large investment out here in a facility, in fact two facilities, and we're continuing to support that effort," he said.

Another "customer" at the test site, Talbot said, is the Defense Threat Reduction Agency, the Pentagon agency that has conducted more than 40 non-nuclear tests in an effort to develop a bunker-buster bomb for crushing deep tunnels in limestone where an enemy could store weapons of mass destruction.

The agency abruptly canceled the final and largest test of the series, dubbed Divine Strake, on Feb. 22 amid opposition from downwinders, politicians and environmentalists. They feared the blast's mushroom cloud would carry dust laced with radioactive particles from historic nuclear tests off the Nevada Test Site.

In announcing the cancellation, agency chief James Tegnelia said his scientists will try to get the data that was expected from Divine Strake by conducting "confirmatory experiments at a much smaller scale."

"That's in the progress of being put together, and Dr. Tegnelia's organization is working on that right now. And that may be future work at the Nevada Test Site," Talbot said.

The series of smaller-scale tests hasn't been scheduled, he said. "But like everything else at the Nevada Test Site, it has to fit inside our environmental impact statement that the state of Nevada has endorsed and regulates and comes and visits and inspects us, too."