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Pentagon wants underground hydrogen bomb

25 March 2002

The Pentagon and the Energy Department have directed the nation's nuclear weapons laboratories in Livermore, Calif., and Los Alamos, N.M., to compete for the chance to design a hydrogen bomb that could destroy targets underground.

To the dismay of arms-control proponents, the Bush administration is advocating such weapons - which would slam into the earth at high speed and then explode underground - as a means of attacking command bunkers or biological and chemical weapons facilities possibly buried in such places as Iraq, Iran or North Korea.

Work on preliminary designs for the weapon - known as the Robust Nuclear Earth Penetrator - begins next month at Lawrence Livermore National Laboratory in northern California and Los Alamos National Laboratory in New Mexico.

Scientists at both labs will propose modifying weapons rather than designing a new bomb from scratch.

That distinction plays a role in arms-control debates in the post-Cold-War era. Arms-control advocates say designing and building new weapons provokes other nations to follow suit, at a time when the fear of ""rogue state'' nuclear weapons is growing.

The Bush White House, like the Clinton administration before it, says it has no plans for new nuclear weapons designs. But critics charge that extensively modifying an existing weapon for a new purpose is equivalent to a new design.

"If I take my Honda into the shop and it comes out a Ferrari, that's not a modification, it's a new car,'' said Marylia Kelley of Livermore, who leads Tri-Valley Communities Against a Radioactive Environment.

She and other opponents argue that producing such weapons blurs the line between nuclear and conventional weapons, increasing the chances that nuclear weapons will be used.

Proponents maintain that nuclear weapons could reach some buried targets that could not be destroyed by conventional bombs. Energy Department officials also say the preliminary design contest will help maintain the skills of scientists at the labs, 10 years after explosive testing of weapons in Nevada came to an end.

Lawrence Livermore's candidate is the B83, a hydrogen bomb designed for the B-1 bomber. Los Alamos will work on the B61, which already has been modified 11 times, including for earth-penetrating use.

The initial design work, officially called feasibility studies, was requested by the Nuclear Weapons Council, a coordinating body of military and Energy Department officials. The three members are Marine Corps Gen. Peter Pace, vice chairman of the Joint Chiefs of Staff; Pete Aldridge, the undersecretary of defense for acquisition, technology, and logistics; and John A. Gordon, the administrator of the Energy Department's National Nuclear Security Administration.

The Air Force, which would drop the Robust Nuclear Earth Penetrator from its airplanes, is also involved in the studies, which are to begin in April after Congress is notified.

"They would lay out the relative advantages or disadvantages of each,'' including cost, said Lisa Cutler of the National Nuclear Security Administration, a branch of the Energy Department. The decision to actually convert the weapons and build the Robust Nuclear Earth Penetrator has not yet been made, she said. But if the program goes forward, the next step would be to chose one of the two competing laboratories to design the weapon.

Lawrence Livermore officials said they could not comment on its feasibility study, the second step in the seven-step process to design and produce a nuclear weapon. Modification of the weapon would keep the nuclear explosives portion of the bomb - known as the "physics package" - largely intact. But the bomb's casing and interior supports would be strengthened.

The Bush administration nuclear weapons policy, laid out in January in the Pentagon's Nuclear Posture Review, de-emphasizes strategic nuclear weapons but promotes the development of "advanced concept'' battlefield weapons such as the earth penetrator.

Earth-penetrating weapons are built long and thin to smash through earth and rock at high speed. In some non-nuclear tests the weapon's exterior casing has melted from the friction. In tests to date, weapons have penetrated only a few dozen feet.

The B83 is 12 feet long and 18 inches in diameter. It was developed at Livermore in the 1980s and has the advantage of already being built to withstand impact. It was designed as a "lay down'' bomb, one that is dropped from an airplane at low altitude and high speed. It is constructed to smash into buildings, knock down trees or careen into cars, and still work. Its detonation is delayed to provide the plane time to clear the area; otherwise, the crew would be flying a suicide mission.

Livermore scientists have studied the B83 as a potential earth-penetrating weapon since the 1980s. Both the B83 and the B61 have a feature known as "dial-a-yield'' in which the bombs' explosive power, or yield, can be adjusted. The maximum yield is more than a megaton, the equivalent of a million tons of TNT, a mountain of conventional explosives. At high yield, the B83 would produce an explosion more than 2 million times more powerful than the "bunker buster'' bombs the Air Force has used against Taliban and al-Qaida caves in Afghanistan.

The B83 at high yield would be perhaps 100 times more powerful than "Little Boy,'' the atomic bomb that devastated Hiroshima in 1945. But by disabling some features, the yield can be reduced dramatically, by some accounts to only 300 tons.

It is believed this is done by switching off the "boosting'' function of the plutonium explosive that begins a series of blasts in a hydrogen bomb.

Despite their potential for low yield, modification of large bombs like the B83 and the B61 would apparently not be affected by a 1994 law prohibiting work on nuclear earth penetrators with yields less than 5,000 tons. That law blocked the development of so-called mini-nukes, but modification of existing weapons might be allowed.

Dan Stober
San Jose Mercury News © 2002 The San Jose Mercury News

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