Tuesday 07 February 2006
For the first time in more than 20 years, U.S. nuclear-weapons
scientists are designing a new H-bomb, the first of probably several new
nuclear explosives on the drawing boards.
If they succeed, in perhaps 20 or 25 more years, the United States
would have an entirely new nuclear arsenal, and a highly automated fac-
tory capable of turning out more warheads as needed, as well as new kinds
of warheads.
"We are on the verge of an exciting time," the nation's top nuclear
weapons executive, Linton Brooks, said last week at Lawrence Livermore
weapons design laboratory.
Teams of roughly
20 scientists and engineers at the nation's two laboratories for
nuclear-explosive design - Livermore and Los Alamos in New Mexico - are in
a head-to-head competition to offer designs for the first of the new
thermonuclear explosives, termed "reliable replacement warheads" or
RRWs.
Designers are aiming for bombs that will be simpler, easier to
maintain over decades and, if they fell into terrorists' hands, able to be
remotely destroyed or rendered useless. Once the designs are unveiled in
September, the Bush administration and Congress could face a major choice
in the future of the U.S. arsenal: Do they keep maintaining the existing,
tested weapons or begin diverting money and manpower to developing the
newly designed but untested weapons?
Administration officials see the new weapons and the plant to make
them as "truly transformative," allowing the dismantlement of thousands of
reserve weapons.
But within the community of nuclear weapons experts, the notion of
fielding untested weapons is controversial and turns heavily on how much
the new bombs would be like the well-tested weapons that the United States
already has.
"I can't believe that an admiral or a general or a future
president, who are putting the U.S. survival at stake, would accept an
untested weapon if it didn't have a test base," said physicist and Hoover
Institution fellow Sidney Drell, a longtime adviser to the government and
its labs on nuclear-weapons issues.
"The question is how do you really ensure long-term reliability of
the stockpile without testing?" said Hugh Gusterson, an MIT anthropologist
who studies the weapons labs and their scientists. "RRW is partly an
answer to that question and it's an answer to the question (by nuclear
weapons scientists) of 'What do I do to keep from being
bored?'"
The prize for the winning lab is tens, perhaps hundreds of million
of dollars for carrying its bomb concept into prototyping and production.
If manufactured, the first RRW would replace two warheads on
submarine-launched missiles, the W76 and W88, together the most numerous
active weapons and the cornerstone of the U.S. nuclear force.
Altogether, the nation has 5,700 nuclear bombs and warheads of 12
basic types, plus more than 4,200 weapons kept in reserve as insurance
against aging and failure of the active, fielded arsenal.
Most are 25-35 years old. All were exploded multiple times under
the Nevada desert before U.S. nuclear testing halted in 1992. It is in
most respects the world's most sophisticated nuclear arsenal, and beyond
opposition at home to continued testing, ending testing made sense to
discourage other nations from testing to advance their nuclear
capabilities.
Faced by the Soviet Union, Cold War weapons scientists devised
their bombs for the greatest power in the smallest, lightest package, so
thousands could be delivered en masse and cause maximum destruction.
Designers compare those weapons to Ferraris, sleek and finely
tuned.
Scientists at the weapons laboratories are laboring to keep the
bombs and warheads in working order, by examining them for signs of
deterioration and replacing parts as faithfully to the original
manufacturing as possible. It is an expensive and not especially
stimulating job.
Some worry that an accumulation of small changes could undermine
the bombs' reliability. So far, every year since 1995 directors of the
weapons labs and secretaries of defense and energy have assured two
presidents that the weapons are safe, secure and will detonate as
designed.
The new reliable replacement warheads are actually an old idea that
1950s-era weapons designers called, with some disdain, the "wooden bomb."
Bomb physicists were proud of their racier, more compact designs and
figured they were plenty dependable already. The wooden bomb by comparison
was boring.
"They said, 'Well heck, that isn't a challenge to anybody',"
recalled Ray Kidder, a former Livermore physicist who found a chilly
reception to proposals in the 1980s for clunkier, more reliable designs.
"It was like saying, 'Well, why don't you make a Model A
Ford.'"
Now the wooden bomb is back in vogue. With fewer, simpler kinds of
warheads, the argument goes, the arsenal could be maintained more
inexpensively and - assuming construction of a factory to turn out the new
bombs on demand - thousands of reserve warheads could be
scrapped.
But in a sharp break with the past, the new bombs would never be
exploded except in war. The only button-to-boom tests of the new arsenal
would be virtual - simulated detonations inside a
supercomputer.
Today's weaponeers say they've learned enough of the complex
physics of thermonuclear explosives to guarantee the bombs would deliver
precise explosive yields even after decades on the shelf. If military
leaders agreed, the most lethal and final resort of U.S. defenses would be
deployed without a test shot.
Ex-military leaders are split on accepting a new, untested nuclear
arsenal.
Former Deputy Secretary of Defense John Hamre told a House
appropriations committee last year that he thinks a new arsenal will be
needed some day. But he said, "I do believe we should test the new weapons
to demonstrate to the world that they are credible."
Eugene Habiger, the senior-most commander over U.S. nuclear forces
as chief of Strategic Command in the mid-1990s, said he would be inclined
to accept the new weapons.
"The science is pretty well understood," he said.
The Bush administration and weapons scientists say the warheads
will not have new military missions. They will ride on the same bombers
and missiles as today's nuclear explosives and strike the same targets.
But administration officials are talk of eventually wanting features
beyond the sizable array of explosive yields and delivery methods
available now: deep earth-penetrating bombs, enhanced radiation weapons
and "reduced collateral damage" bombs with lower fission
radiation.
Designers and executives at Lawrence Livermore are taking a
conservative line. The lab's weapons chief, Bruce Goodwin, talks of
starting with nuclear-explosive designs that are well tested and well
understood.
"Our plan is to develop a design that lies well within the
experience - and within what we call the 'sweet spot' - of our historical
test base," he said in a recent statement.
One candidate under consideration as a starting point is the W89, a
200-kiloton warhead designed for a short-range attack missile. It is
well-tested, plus it comes from a long line of well-understood designs and
uses every safety and security feature available at the time.
Yet weaponeers at Los Alamos lab and Brooks, as the head of the
National Nuclear Security Administration, have talked of a more
freewheeling design effort.
"This is not about going back to rake over old designs. That's why
I've got two different teams of weapons scientists at two labs working on
this," Brooks said. "There's never been anything tested that will do the
sorts of things we want to do."
Such talk alarms Stanford's Drell.
"How the hell do you make a new design without testing?" he said.
"Those kinds of flamboyant statements worry me because I don't believe we
could maintain a confident stockpile with new designs that haven't been
tested."
Some former weapons scientists say the wiser course is maintaining
the current arsenal and boosting its reliability in simple ways, such as
adding more tritium to "sweeten" the hydrogen gases at the very core of
the weapon.
"We've got a reliable stockpile. We have a test base for it. We
have now in the last 10 or 15 years far more sophisticated computational
abilities than we had doing these designs originally, so things are
extremely well understand in terms of the performance," said Seymour Sack,
once Livermore's most prolific designer, whose innovations are found in
nearly every U.S. weapon. "I don't see any reason you should change those
designs."
Lawmakers say they are watching carefully to make sure the new
warheads hew closely to existing, well-understood designs. But in a recent
report on the new warhead program for the Livermore watchdog group,
Tri-Valley CAREs, former White House budget analyst Bob Civiak said
Congress has a poor record of restraining the weapons design labs from
what after all they were built to do.
"Congress thinks it can allow the labs to design new nuclear
weapons but restrict them to existing designs," he said. "History shows
that cannot be the case."
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