H-bombs.

If approved by the nations chief weapons executive, over the next decade the lab could as much as double its plutonium inventory to

1.5 tons, enough in theory to make hundreds of nuclear weapons.

The lab also plans to double the plutonium that workers in a single room may handle to more than 80 pounds, so scientists can proceed with multiple projects simultaneously.

According to a new study of Livermores environmental impacts for the next decade, to be officially released next week, a major reason for enlarging plutonium storage at Livermore is building an experimental production line for casting plutonium pits. These hollow, usually oblong shells about the size of a softball, when wrapped in high explosive and plugged with detonators, serve as the miniature A-bombs that touch off modern thermonuclear weapons.

The United States lost its sole pit factory in 1989 with the forced closure of the Rocky Flats plant outside Boulder, Colo., and only recently has been making single warhead pits, one by one, at Los Alamos lab. Many weapons scientists say not having a pit factory is taking too much risk with the U.S. arsenal.

Arms-control and environmental activists portrayed the added plutonium work as risky for the health and security of the San Francisco Bay Area.

In a worst-case accident of a fire sweeping through an entire room fully stocked with plutonium at LivermoresSuperblock, the governments calculations predict one chance in 10 that a single person out of the Bays 7 million population would get cancer attributable to the fire.

Marylia Kelley, head of the Livermore-based watchdog group Tri-Valley CAREs, suspects thats an understatement of the risk from more plutonium, including that posed by terrorists and nearby earthquake faults.

Where theyve chosen to work the bugs out of the technology for a bomb factory is a highly populated area riddled with earthquake faults. Its crazy. If you tried, you could not find a more inappropriate location.

Arms-control groups and good-government watchdogs have pressed two U.S. energy secretaries to empty Livermore of its plutonium, arguing among other things that the close proximity of homes makes it impossible for security forces to use heavy weapons in defending the lab.

We believe plutonium cannot be made safe at Livermore, Kelley said. But she praised the National Nuclear Security Administration for scrapping plans to use exotic lasers to separate plutonium.

NNSA officials studied the proposal more closely and found it was unnecessary in light of a glut of plutonium in the U.S. nuclear weapons complex.

By eliminating laser isotopic separation, the NNSA cut by a third the amount of plutonium that workers might handle at any given time and cut the cancer risk from an accident at the plutonium Superblock facility almost in half.

We have a lower waste projection and a lower radiological risk to workers, said Tom Grim, NNSAs leader for the study.

In a new twist, his agency also is proposing to use small amounts of plutonium, uranium and lithium hydride — the essential ingredients to all modern H-bombs — in experiments at the National Ignition Facility, a Rose Bowl-size laser that focuses 192 beams on a space smaller than a thimble.

In December 1995, federal weapons officials said they had no plans to ever use those materials inside the giant laser. Nonproliferation experts worried their use could lead to new classes of extremely low-yield weapons and almost pure-fusion weapons.

But weapons scientists say the laser experiments on plutonium are strictly for generating neutrons to test their effects on weapons components or to improve understanding of basic plutonium physics, such as how the quirky metal behaves at high temperatures and pressures.

More than 9,000 people commented on the governments proposals, most of them highly critical of the plans in its 18-pound, four-volume study. Grim dismissed the majority as staged.

I think the general public understands that the NNSA is looking after homeland security and is improving security not only for them and their families but also the world, he said.

The study will be available by the end of next week at the Livermore and Tracy public libraries, in the lab reading room off Greenville Road and on the Web at www-envirinfo.llnl.gov

Contact Ian Hoffman at ihoffman@angnewspapers.com.