November 28, 2000
By JAMES GLANZ
LOS ALAMOS, N.M. They called it "shaking the desert." For 40 years,
the guardians of the nation's nuclear stockpile exploded bombs
beneath the arid ground at a test site in Nevada, both to test new
types of bombs and to be certain that old ones still worked as
designed. Many of those tests also shook the desert from above, in
the atmosphere, before a treaty banned the practice in 1963.
But since 1992, when the United States declared a moratorium on
all nuclear tests, the desert has been still. Since then the nation
has evaluated the thousands of warheads in its aging arsenal in a
program called science-based stockpile stewardship, using computer
simulations, experiments on bomb components and other methods to
assess the condition of the weapons without actually exploding
them.
Program officials have been confident that the stockpile is safe
and secure and that the stewardship program can fully maintain the
weapons. Now, however, some of the masters of nuclear weapons
design are expressing concern over whether this program is up to
the task.
Concerns about the program take a variety of forms, including
criticisms of its underlying technical rationale and warnings that
the program's base of talented scientists is eroding, and the
experts do not speak with a single voice.
Many program supporters complain that onerous new security rules
put in place after the arrest of Dr. Wen Ho Lee, the scientist who
pleaded guilty to one count of mishandling nuclear secrets, have
damaged the program by hampering research. They say the rules are
also discouraging young researchers from entering the field at a
time when weapons designers of the testing era are nearing
retirement and must transmit their knowledge to a new generation.
A number of other weapons experts go even further, saying the
concept of trying to assess the stockpile in the absence of nuclear
tests is intrinsically flawed. Without exploding a sample of the
bombs, they say, they can never reach clear-cut conclusions about
the continued reliability of a given weapon design.
A stewardship program with no testing is "a religious exercise,
not science," said Dr. Merri Wood, a senior designer of nuclear
weaponry at Los Alamos National Laboratory. Dr. Wood said that as
the weapons aged, it was becoming impossible to say with certainty
that the stockpile was entirely functional.
"I can't give anybody a safe period," she said of the possibility
that some weapons could become unreliable. "It could happen at any
time."
Dr. Charles Nakhleh, another weapons designer at Los Alamos, said
doubts about the stewardship program were widespread among weapons
designers. "The vast, vast majority would say there are questions
you can answer relatively definitively with nuclear testing that
would be very difficult to answer without nuclear testing," he
said.
Nuclear Politics
These comments provide an unusual glimpse into the secretive world
of the nation's weapons designers at a time of heightened political
awareness about the pros and cons of nuclear testing. Only a year
ago, doubts about the stewardship program helped defeat the
Comprehensive Test Ban Treaty, which would ban all nuclear tests.
During the treaty debate, the directors of the nation's three
major weapons laboratories testified that the program was working
well. But their testimony was widely viewed as lukewarm. Few
weapons designers spoke openly about the topic at the time, but the
treaty debate itself appears to have encouraged some scientists
within the program to begin to speak out.
Senator Pete V. Domenici, the New Mexico Republican who voted
against the treaty and whose state contains two of the three major
weapons laboratories, strongly praised the designers' willingness
to discuss their concerns. Stressing his own neutrality on the
issue, Mr. Domenici said he would consider holding hearings on
"possible shortcomings" in the stewardship program.
Beyond the treaty debate and the continuing fallout from the Wen
Ho Lee case, many weapons scientists say that the effects of
materials' aging, cracking and deteriorating in the stockpile
become increasingly apparent with each passing year, generating
intense scientific discussion and debate.
Jim Danneskiold, a spokesman for the Los Alamos laboratory,
acknowledged those findings. But in the laboratory's most recent
review of the stockpile at the laboratory, its director, Dr. John
Browne, concluded that despite the criticism of some lab scientists
the aging stockpile was safe and reliable. The review, called
certification, involves several labs and government agencies.
"Although there are a growing number of aging findings in the
stockpile, at present Los Alamos doesn't see a need to recommend a
return to underground testing," Mr. Danneskiold said.
Energy Secretary Bill Richardson said four formal certifications
from 1996 through 1999 had found that "the stockpile is safe and
secure."
Steve Andreasen, director of defense policy and arms control of
the National Security Council at the White House, said the
stewardship program was specifically designed to encourage
skepticism so that any possible problems would be found.
"I'm not surprised that there are people within the program who
are skeptical," he said. "They are working hard with the many who
are confident that we have the right program for stewardship. And
the fact remains we have four solid certifications under our belt."
Any proposal to resume nuclear testing would almost certainly
lead to a political and diplomatic firestorm. But in endorsing the
treaty, President Clinton pointed out that it contained a "supreme
national interest" clause that would allow the nation to resume
testing if at some point the safety and reliability of the nuclear
stockpile could no longer be certified.
Outguessing Nature
The program is a fiendish technical challenge, and even its
backers concede that science-based stockpile stewardship can never
offer the certainty of the big explosions.
The thousands of bombs in the stockpile are highly complex
devices. Each is made up of a forest of electronics and missile
components surrounding a sort of atomic fuse, or "primary," that
holds chemical explosives and a fission bomb containing a fuel like
plutonium. In addition, there is a "secondary," whose thermonuclear
fusion reaction is set off when the primary explodes.
Most of the weapons in the stockpile were not built with longevity
in mind. It was expected that they would be replaced by a
continuing stream of new and improved designs, checked in tests
until weapons production abruptly stopped in 1992. But the basic
design of the newest of the bombs, a version called the W-88,
received crucial tests in the 1970's and was fully designed by the
mid-1980's. Production of the weapon ended by 1991. The oldest of
the bombs date from 1970.
Assessing the changes can be bewilderingly difficult. The
degradation turns symmetrical components shaped like spheres or
cylinders into irregular shapes whose properties are a nightmare to
model in computer simulations. Inspectors, who typically tear apart
one weapon of each design per year and less intrusively check
others, find weapons components deteriorating in various ways
because the materials age, and because they are exposed to the
radioactivity of their own fuel. Even tiny changes in those
materials can lead to large changes in bomb performance, weapons
designers say.
Supporters of the program say that regular inspections of the
weapons will turn up any serious problems as the stockpile ages
and that those problems can be addressed.
"You'll get the warning bell and you'll know what to do," said Dr.
Sidney Drell, a physicist at the Stanford Linear Accelerator
Center, who led a study in 1995 that underlies the stewardship
program. Dr. Drell said he remained optimistic about scientists'
ability to limit that element of doubt, which he called "genuine
and serious."
But other experts at the nation's weapons laboratories are
challenging this view. Designers say the sensitivity of the bombs
to slight changes means that age could modify the bombs so that
they do not work as they are supposed to. While program supporters
believe those problems can be found and fixed, virtually everyone
agrees that if any major redesign is needed, those new bombs could
not be certified as reliable under the current program.
Dr. Harold Agnew, a former director of Los Alamos, said that "to
consider putting those things in the stockpile without testing is
nonsense." He is on the panel for a new study by the National
Academy of Sciences that will examine many of the issues
surrounding the Comprehensive Test Ban Treaty, including stockpile
stewardship.
"In a blink, I would prefer to go back to testing," said Dr. Carol
T. Alonso, a weapons designer for 20 years who is now assistant
associate director for national security at Lawrence Livermore
National Laboratory in California.
Thomas Thomson, a weapons designer at Livermore, said that under
the current program, "I think you just accept the fact that you're
going to have a decline" in the reliability of the stockpile. "You
try to make it as gradual as possible," he added.
Reid Worlton, a retired Los Alamos weapons designer who is still
involved in the program, said, "There's nothing that really can
replicate a nuclear test totally."
Big Bill, No Guarantees
The stockpile stewardship program will cost the nation about $5
billion in the fiscal year that started Oct. 1; since the
mid-1990's it has cost more than $20 billion. An official at the
Energy Department estimates that perhaps 25,000 workers of all
kinds, from guards to chemists, participate. That includes
thousands of scientists and engineers and roughly 50 senior
designers.
In addition to some of the most powerful computers in the world,
the program requires tests of bomb components and data like that
produced by the $260 million Dual-Axis Radiographic Hydrodynamic
Test center at Los Alamos, where flashes of X-rays study exploding
primaries from which the fission fuel has been removed. A $4
billion laser, under construction at Lawrence Livermore National
Laboratory, is expected to create even more extreme conditions by
crushing pellets of fusion fuel.
Even with all these tools, critics say, crucial questions about
the performance of aging bombs must still be answered directly by
data from old tests. Because bombs this old were never tested, they
say, computer simulations cannot definitively determine the
seriousness of new types of changes caused by continued aging.
Dr. Michael R. Anastasio, associate director of defense and
nuclear technologies at Livermore and a supporter of the stockpile
stewardship program, said it would be "at least 10 years" before
scientists would be able to say for sure whether the approach could
replace nuclear tests.
"We've said all along that the science-based stockpile stewardship
program is the best program we know how to construct to meet the
goals of sustaining confidence without nuclear testing," Dr.
Anastasio said. "But we've always said there's no guarantee that it
will work."
But Madelyn Creedon, the top official for day-to-day management of
the stewardship program at the Energy Department, said the new
computer simulations had already been able to answer questions
about the stockpile that in the past would have required tests. "We
keep pressing ahead and we keep having successes," she said. "The
evidence shows that stockpile stewardship is doing the job."
Policing the Stewards
But can it keep doing the job? Serious
questions about the operation of the stockpile program are being
heard at all three of the major American weapons laboratories: Los
Alamos, Livermore and Sandia. Open criticism of it appears to be
most widespread at Los Alamos, where the Wen Ho Lee case and a
later security lapse have led to an especially intense focus on
tightened security. While the case against Dr. Lee, a former Los
Alamos nuclear scientist, came to a close in September when he
pleaded guilty to a single count of mishandling nuclear data,
several investigations are still proceeding, including one
involving the apparent theft of plans for the nation's most
advanced warhead, the W-88.
Even weapons designers who support the stockpile stewardship
program say the new security restrictions have made what would have
been a difficult job under any circumstances even harder.
As an example of new security measures that have hindered bomb
stewards' work, Dr. Michael Bernardin, a senior weapons designer at
Los Alamos, cited the suspension of the so-called two-hour rule
involving computer security after an incident in June when two hard
drives containing nuclear data were lost and later recovered at Los
Alamos. The rule had allowed computers involved in classified
projects to remain running for up to two hours inside secure areas
of the lab as scientists left to get coffee or take a break.
When the rule was suspended, any break, no matter how brief, meant
the computers had to be shut down, halting work in midstream and
all but shutting down many research activities. (Mr. Danneskiold,
the Los Alamos spokesman, said a delay of more than a month in this
year's certification work at the lab was partly the result of the
suspension of the rule.)
"At that point, I and everybody else I know was ready to quit,"
said Dr. Nakhleh, the Los Alamos weapons designer. Security
officials later reinstated the two-hour rule, but scientists at Los
Alamos say other cumbersome procedures remain.
As a result of all this, according to officials at the weapons
labs and at the Energy Department, which runs them, there has been
a flight of scientific talent and a decline of top-flight
applicants, problems exacerbated by a rise in lucrative job offers
from the private sector.
Weapons experts say the frustration over tighter security
procedures comes at a particularly unfortunate time, as the
scientists who designed and tested the weapons in the stockpile try
to pass their knowledge and experience to new caretakers before
retiring or dying. "We have a five- year window to make this
transfer," Dr. Bernardin said.
Critics of the bomb culture say old- line weapons designers are
talking about nuclear testing now because they are unable to adapt
to new tools, like superfast computers, that may make testing
obsolete. Tom Z. Collina, director of the arms control and
international security program at the Union of Concerned
Scientists, said the mixed message from the laboratories suggested
"that they want to leave the door open to the resumption of testing
and at the same time continue to get stockpile stewardship funds."
But Dr. Nakhleh, who is one of the young scientists working full
time in the program, says testing is simply a more scientific
approach.
One way to get around all these criticisms of the program and
still avoid testing, some scientists outside the laboratories say,
would be simply to "remanufacture" new, nearly exact replicas of
existing weapons in the stockpile and replace them on a regular
basis as they age. Neither very much science nor underground
testing would be necessary.
But Dr. Jas Mercer-Smith, a former weapons designer who is deputy
associate director for nuclear weapons at Los Alamos, said that was
easier said than done, since many manufacturing techniques of the
past were no longer available, and the copies could in reality be
significantly different from the originals. Without the
sophisticated scientific analysis of the stockpile stewardship
program, he said, nuclear experts could not be sure what effects
the changes might have.
Dr. Bernardin of Los Alamos said possible new military needs,
anything from building nuclear-tipped missile interceptors to
replacing an existing weapon completely if it became too old to
function, could someday require entirely remade designs as well.
Supporters of remanufacture insist that no new designs are needed
because the nation's nuclear deterrent is sufficient. If they are
needed, however, the uncertainties and complexities involved in any
new designs would inevitably require underground tests, and not
just computer simulations, several weapons designers said. Those
complexities, Dr. Wood of Los Alamos said, mean that even existing
designs are now coming into question.
"If this was somebody's hair clip, I wouldn't mind as much," she
said. "But it's not."
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