By John Fleck
Los Alamos National Laboratory and the Department of Energy have draped
a veil of secrecy around plans to detonate plutonium at Los Alamos. Behind
the veil is the question of whether the department and the laboratory
plan to build and detonate full-scale replicas of nuclear weapons, down
to the radioactive plutonium at their cores.
The department and the lab acknowledge that they plan to use explosives
to detonate plutonium inside steel vessels. The purpose, they say, is
to study how the plutonium behaves at high temperatures and pressures.
The DOE also acknowledges plans to build mock bombs with uranium and other
metals substituting for the plutonium. But the DOE refuses to say
whether those two ideas will be combined -- tests using a full-scale plutonium
mockup of a nuclear weapon.
Arms control activists believe the agency is planning plutonium mock weapons
tests, which they say would have serious arms control implications. By
using a rare type of plutonium, lab scientists could avoid a nuclear blast
while getting extremely accurate data on the early stages of a bomb's
detonation, physicists say. The tests could be used not only to
study the existing U.S. arsenal but also to design new weapons, experts
say. Such tests would violate the spirit of a nuclear test ban being
negotiated in Geneva because the purpose of the ban would be to halt the
design of new weapons, said Christopher Paine, an arms control expert
with the Natural Resources Defense Council in Washington, D.C.
Energy Department documents don't answer the question of whether mock
weapon tests with plutonium are planned, and the department hasn't complied
yet with a Freedom of Information Act request the Journal filed 17 months
ago seeking documents that would answer the question. Asked directly
whether such tests are planned, a laboratory spokesman wouldn't answer.
The reason for the secrecy is that the DOE's Office of Nonproliferation
has blocked efforts to declassify information about the tests, said Bryan
Siebert, head of the DOE's office of classification. That allows
the DOE to avoid having a public discussion of such questions, said Steve
Aftergood, an analyst of government secrecy policies with the Federation
of American Scientists, a Washington, D.C., think tank.
It is no secret that Los Alamos wants to blow up some plutonium, the radioactive
metal at the heart of nuclear weapons. In documents made public
over the past year, laboratory officials acknowledge plans to conduct
explosive tests with plutonium to better understand how it behaves under
high temperatures and pressures during the first millionth of a second
of a nuclear blast. But it's unclear whether they plan to conduct
basic science experiments with it, slamming arbitrarily shaped pieces
of plutonium with high explosives to see what happens, or whether they
plan to assemble it into a simulated nuclear weapon.
The plutonium tests would be conducted at Los Alamos' Dual Axis Radiographic
Hydrodynamic Test Facility - DARHT. The partially built DARHT plays
a major part in the DOE's plans to replace underground nuclear blast tests
with non-nuclear experiments. Officials say the program's purpose is to
maintain the safety and reliability of existing U.S. weapons. DARHT's
construction was halted in January 1995 when anti-nuclear activists sued,
but U.S. District Judge E. L. Mechem issued an order recently allowing
construction to resume.
DARHT would take high-resolution X-rays of an explosive blast slamming
into plutonium or other metals, simulating the plutonium's behavior during
the first stages of a nuclear blast. In a nuclear weapon, a sphere
of plutonium is surrounded by high explosives. When detonated, the explosives
rapidly compress the plutonium, liquefying and squeezing it to the high
density needed to begin a nuclear chain reaction. That reaction releases
the bomb's tremendous explosive energy in an instant.
At DARHT, scientists plan to substitute materials that can be squeezed
without setting off a nuclear chain reaction, allowing them to study the
final instants before the nuclear explosion would begin in a real bomb.
Critics believe those plans include a rare type of plutonium being produced
in small quantities at the Energy Department's Savannah River factory
in South Carolina. Plans for the South Carolina plutonium are classified,
but independent scientists say the material would be perfect for such
tests because it wouldn't undergo the same nuclear chain reaction as weapons-grade
Weapons-grade plutonium is made primarily of plutonium-239. The number
identifies the element's atomic weight. The plutonium being produced
in South Carolina, plutonium-242, has the same physical and chemical properties
as weapons-grade plutonium. But it takes 10 times as much plutonium-242
to start a nuclear chain reaction, according to physicist Tom Cochran,
a nuclear weapons expert at the Natural Resources Defense Council.
That means a mock nuclear weapon made of plutonium-242 instead of weapons-grade
plutonium would behave like the real thing up to the time the bomb's nuclear
chain reaction begins. "You could exactly duplicate the weapon essentially
in all respects," Cochran said.
Pictures taken during that time would thus give scientists an accurate
picture of the weapons' behavior. DOE and laboratory officials won't
comment on whether they plan to do tests with plutonium-242, or whether
the plutonium will be assembled into a mock weapon. Siebert said
that Los Alamos is not to blame for the secrecy. "I don't think it's Los
Alamos' fault. They're just following the rules," he said.
While not commenting directly on the plutonium tests, Siebert said there
is a conflict within the DOE regarding whether information about "the
material being used in DARHT can be declassified." Officials in
the nuclear weapons program and Siebert's office support declassifying
it, while nonproliferation program officials are opposed. Classification
rules, Siebert acknowledged, have left "a road-block" in the way of a
public discussion of the question.
"I can't confirm or deny what's going to be used in the DARHT project
nor whether or not Savanna River's involved in a project to support the
DAHRT facility, and that's because the material involved is still classified,"
Siebert said. Details about the plutonium tests were included in
a classified appendix to the DOE's environmental study of DARHT. Mechem,
in his recent ruling, said that environmental laws didn't require the
information to be revealed to the public.
A multi-volume DOE environmental study of the U.S. nuclear weapons complex
released in February also segregates all information about "the purpose
of and need for the plutonium-242" in a classified appendix. According
to Princeton University physicist Frank von Hippel, there is no other
obvious use for plutonium-242 except conducting tests of full-scale weapon
configurations without inducing a nuclear blast. The secrecy surrounding
plutonium-242 puzzles von Hippel, a prominent member of the arms control
community, because the plutonium's usefulness as a surrogate weapons material
is common knowledge among nuclear scientists.
"They've been very reticent about talking about (plutonium-)242 although
everybody seems to know about it," he said. "I don't know what's so secret
about that. You'd have to be brain dead" not to figure out plutonium-242's
usefulness for weapons simulation. The real issue, said Paine, is
the role plutonium-242 tests might play in skirting the intent of the
Comprehensive Test Ban Treaty. Public acknowledgement of the tests
would make the United States look bad while it is arguing in favor of
a total ban on even modest tests with nuclear yields, Paine said.
Slight Chance of Big Mishap Worries Critics
The chances of a plutonium-scattering accident from explosive tests
at Los Alamos National Laboratory are small, but the risks, if one happens,
are large, supporters and critics of DARHT agree.
"An accident is very unlikely, but an accident would be very, very bad,"
said Santa Fe activist Greg Mello, a member of the Los Alamos Study
Group and one of DARHT's most vocal critics. The DOE contends, in a
detailed environmental study on the explosive tests, that the chances
of a plutonium-releasing accident are extremely small -- once every
thousand to million years of normal operations. Plutonium experiments,
in which the dangerous metal would be detonated with high explosives
to study it, would be conducted within double-walled steel containment
vessels, according to plans being formulated by Los Alamos National
Laboratory and the Department of Energy.
The chances of one of those containment vessels being breached is a
once-in-a-million years possibility, according to the DOE's analysis.
A more serious accident, in which a plutonium test device accidentally
went off before it was placed inside its containment vessel, is likely
to happen somewhere between once in a thousand years and once in a million
years, according to the DOE's study. Critics disagree with those
estimates. "I believe that these accidents are unlikely, but
not that unlikely," Mello said.
But both sides agree that an accident, if it happened, would be serious.
The most serious accident, with a plutonium device going off outside
its containment vessel, would cause an estimated 5 to 12 cancer deaths
in the downwind population, a calculation based on a computer simulation
of such variables as wind speed and direction, according to the DOE's