TIME: Almanac 1993/TIME Almanac 1993.iso/time/060490/0604107.000

Text File | 1992-08-28 | 5.6 KB | 118 lines

                                                                                NATION, Page 53

Accident-Prone -- and Lethal


Doubts rise on the safety of three types of nuclear warheads


     The W-79 is an artillery shell, the W-88 rides atop
missiles that would be fired from submarines and the W-69 is
the business end of missiles designed to be launched from
bombers at ground targets. Despite the diversity of their
delivery systems, these three weapons, which together make up
about 10% of the total U.S. inventory of nuclear warheads,
share a frightening characteristic: all are, or have been,
subject to safety problems that some experts fear just might
cause them to explode accidentally.

    Almost certainly, an unintentional blast would detonate only
the chemical explosives that, if fired deliberately, would
compress the warhead's plutonium cores and touch off an
unstoppable atomic chain reaction. Some experts see a slim
chance of a nuclear explosion in the case of the W-79 artillery
shell, but the far more likely result would be a chemical blast
that could release deadly radioactive plutonium or uranium from
the cores. The safety problems, disclosed last week by the
Washington Post, were promptly confirmed in public congressional
hearings. The difficulties seem sure to complicate immensely
a review under way of how many and what kind of nuclear weapons
the U.S. should deploy in the light of easing cold-war tensions
and prospective arms-control deals with the Soviets.

    The story begins in 1988, when scientists at the Lawrence
Livermore National Laboratory near San Francisco set some new,
supersophisticated computers to simulating the effects of
nuclear blasts. One unexpected conclusion: the chemical
explosives in a W-79 artillery shell could be detonated if the
shell were struck in a single sensitive spot, perhaps by a
stray bullet. One military official told the Washington Post,
"For a while, we were also worried that these things might go
off if they fell off the back of a truck." More than 300 of the
shells were reportedly shipped to the U.S. from West Germany,
the Netherlands and South Korea, where they had been deployed,
then repaired and sent back. Nebraska Democrat J. James Exon,
who chaired Senate Armed Services Sub-committee hearings last
week, accepts Pentagon assurances that the shells are now
entirely safe, but the Pentagon and State Department
nevertheless are bracing themselves for an outcry from
overseas.

    The W-79 problem prompted computer studies of other
warheads, which led to questions about the safety of a far more
important weapon, the brand-new W-88 warhead carried by D-5
missiles fired by Trident II submarines. The D-5 is one of the
principal weapons that would be launched at the Soviet Union
in a nuclear war. Some scientists contend that the design of
the third stage places too much rocket fuel too close to the
warheads. Conceivably the fuel could ignite and detonate
chemical explosives in the warhead while the missile was being
handled in port, producing a potentially heavy leakage of
cancer-causing plutonium dust near Trident bases in Washington
State and Georgia. Other experts furiously dispute these
findings, which will be examined by a panel of three scientists
appointed by Congress with Pentagon acquiescence.

    The panel will also look into a hot dispute about the SRAM-A
(for  Short-Range Attack Missile), another weapon that would be
launched in a nuclear war against the U.S.S.R.: it is carried
by bombers on airborne alert and designed to knock out Soviet
radar installations, defensive missiles and airfields. The fear
is that a fire aboard a bomber could ignite the missile's
volatile fuel, which in turn could detonate some of the
chemical explosives in its W-69 warhead.

    At last week's Senate hearings, directors of three
nuclear-weapons laboratories, including Livermore, unanimously
argued that the SRAM should be taken off the bombers flying on
alert, put into storage and made removable only at a base
commander's order. John Tuck, Under Secretary of the Department
of Energy, which builds nuclear weapons and shares
responsibility with the Pentagon for their safety, told the
subcommittee, "I think that's the direction we're going."
Pentagon spokesman Pete Williams, however, insisted that the
Air Force would keep the warheads on "alert" status, at least
until the safety study is completed. But the Pentagon may have
trouble maintaining that stand in the face of public pressure;
Secretary of Defense Dick Cheney scheduled a weekend meeting
with weapons-laboratory scientists and Energy Secretary James
Watkins to consider what to do. SRAM-A is scheduled to be
replaced eventually by a longer-range missile, SRAM-II.
However, the problems with the older weapon might keep NATO from
approving a future tactical version for use in Europe, the
SRAM-T, even though it may be safer. One congressional source
predicts that "there will never be a SRAM-T."

    "The common thread in the three systems," says Exon, "is the
problem of previous-generation high explosives." All three
weapons carry them, rather than a less volatile Insensitive
High Explosive, which is heavier and thus decreases the range
of a missile or artillery shell. By presidential order IHE
nonetheless has been used in all new weapons built since 1985
-- with, however, at least one exception. Even after that date,
defense planners decided not to switch to IHE in the Trident
W-88 warhead. That is a design trade-off that the Pentagon may
soon bitterly regret.


By George J. Church. Reported by Bruce van Voorst/Washington.