B etween 1951 and 1992, the United States set off nearly a thousand nuclear bombs
at the Nevada Test Site, an empty and awesome stretch of desert whose cratered surface resembles the face of the moon. Throughout the site's 1,350 square miles are the remains of houses, fortified bunkers, and parking garages, structures built to see how much damage bombs of various sizes could do. Visible amid the detritus of bomb blasts are simple examples of plutonium's power—telltale shards of the radioactive green glass that is created at ground zero during a nuclear explosion.
As I toured the desert recently with some of the men who specialize in the arcane art of detonating nuclear weapons, it occurred to me that the Americans who mastered plutonium had plenty in common with the smiths and chemists who first mastered iron, bronze, copper, and steel. Every great empire in history, from the Greeks to the British, has been founded on an ability to manipulate metal into new and ever more lethal forms.
Plutonium, the metal that made the American Century possible, was manufactured by thousands of people, organized by a rich, centralized democratic state devoted to the a
A pellet of plutonium-238 glows with the heat of its own radioactivity. The metal
does not occur naturally but is produced as a by-product of fission in nuclear reactors.
dvancement of military science. The deadliest products of this effort are thousands of hollow grapefruit-size plutonium "pits" that power America's nuclear weapons. Our arsenals house roughly 24,000 plutonium pits, of which some 10,600 are inside nuclear weapons. Each pit, slightly warm to the touch, has about 30 parts, which are often coated with nickel or beryllium. Engineered to extraordinary tolerances, the parts fit together like a three-dimensional puzzle.
Yet this metal largely remains a mystery even to the scientists who know it best. In "An Update," one of several dozen recently published papers on plutonium by scientists at Los Alamos National Laboratory, George Chapline and James L. Smith write: "After more than 50 years of plutonium research at Los Alamos, we might be expected to understand the strange properties of this metal. Instead, we are still stumped."
P lutonium, element 94 on the periodic table, is as old as the universe itself, formed
in the blowoff from ancient supernovas, massive stars that explode after exhausting their fuel. The thermonuclear reactions in the stars created extraordinary heat and pressures that ripped small atoms like hydrogen and lithium apart and recombined their parts to produce larger atoms like plutonium. Because plutonium has a half-life of 81 million years, nearly all traces of it had vanished by the time Earth cooled 4 billion years ago. Plutonium reappeared on Earth for a brief moment 2 billion years ago in Africa, in what is now Gabon, where plant life oxidized and reduced a deposit of 10 tons of uranium oxide to uranium ore. Fission in the uranium created a smaller deposit of plutonium, which decayed back into uranium.
The first meeting between plutonium and mankind occurred on February 23, 1941, when a young chemist named Glenn Seaborg used a chemical process to isolate a minute quantity of element 94 in a laboratory in Berkeley, California. Seaborg named it after Pluto, the most recently discovered and least-known planet in the solar system. Pluto is what the Romans called the Greek god Hades, lord of the underworld. Seaborg chose the letters Pu as a joke, which passed without notice into the periodic table.
Toxic, mysterious, and possessing the ability to combine with nearly every other element in the periodic table, plutonium would be at home in the underworld of the Greeks or in Dante's Inferno. It can be as brittle as glass or as malleable as aluminum. Plutonium-239, a variant of the element Seaborg discovered, is 1.7 times as likely as uranium to fission, making it the perfect fuel for a nuclear bomb. Two pounds of the metal contain the potential energy of 20,000 tons of high explosive, a millionfold increase over the power of chemical explosives like TNT.
The first usable quantities of plutonium were produced in February 1944. The metal delivered to Los Alamos was unlike any other on Earth. The plutonium corroded nearly every container it was put in. At only 300 degrees Fahrenheit, it could spontaneously ignite, making it all but impossible to shape or roll. Gallium was added to help it retain a cubic crystalline state. While pure plutonium at room temperature fractured like cast iron, the alloy resembled steel. It could be cast, pressed, machined, and assembled into shapes designed by the engineers of the Manhattan Project.
The basic idea that guided the working of the first bomb was so simple that any smart high school student could understand it. A sphere of plutonium was surrounded by a mantle of high explosives. Detonated, the explosive crushed in on the plutonium. As the density increased, the distance between the nuclei decreased, setting off a chain reaction. On July 16, 1945, the Trinity test at Alamogordo, New Mexico, proved the power of plutonium-based weapons. As the blast unfolded, physicist J. Robert Oppenheimer, leader of the Manhattan Project, quoted from the Bhagavad Gita: "Now I am become death, the destroyer of worlds."
R eligious references in the plutonium age were hard to avoid, even for die-hard
materialists like Oppenheimer. Plutonium-based weapons offered ultimate power and operated on a plane of existence not visible to the naked eye. Early prophets promised safe, cheap plutonium energy for all mankind. That vision never materialized. Instead, a vast weapons complex grew in the United States in great secrecy, a world of laboratories, testing sites, and production facilities that produced more than 100 tons of plutonium. The plutonium and tritium that fueled America's nuclear arsenal were cooled by the Savannah River at Aiken, South Carolina, and the Columbia River at Hanford, Washington. Pits for bombs and warheads were designed at Los Alamos and at the Lawrence Livermore National Laboratory in California. The Sandia National Laboratories in New Mexico and California designed the weapons systems that could carry the bombs to their targets.
Today the majority of America's plutonium arsenal is kept in sealed bunkers near Amarillo, Texas—the last stop on the assembly line that produced finished nuclear weapons. Plutonium pits were formerly made at the Rocky Flats Plant in Colorado, which was shut down in 1989 for gross violations of environmental law. Since then, the United States has lost the ability to mass-produce pits for weapons, and the reliability of some of our existing weapons has become questionable. As plutonium decays, it produces helium, which spreads through the lattice, causing the metal to swell. Over time, the explosive power of the plutonium decreases, and bombs stop working in the way they were designed.
In place of testing live warheads in the desert, our national laboratories now employ complex computer simulations to try to predict how aging plutonium-based weapons might behave. With the end of the test program, a degree of certainty has been lost. Would our nuclear warheads actually detonate if the president chose to use them? Probably—but it is impossible for us to know for sure. What is clear is that, in less than a decade, all the weapons in the American nuclear arsenal will have outlived their expected lifetimes, and the last American nuclear weapons designer with test experience will have retired from the laboratory. The end of the plutonium age may lie on the not-so-distant horizon.
The end of the plutonium age means the end of the stabilizing logic that followed World War II. In a world that has been remade by a band of fanatic hijackers, the notion of nuclear deterrence seems increasingly quaint. As the plutonium pits decay and the old security structures collapse, the apocalyptic potential inherent in the metal becomes more immediate and terrifying, and the illusion that we are its master becomes ever harder to sustain.
PLUTONIUM IS FOREVER
There are 260 tons of weapons-grade plutonium-239 in the world—enough to build 85,000 warheads. The United States has roughly 90 tons, most of which is stored at Department of Energy sites. Most information about plutonium storage remains classified. larger image
Nuclear Watch is a New Mexico–based watchdog group dealing with nuclear weapons policy and nuclear environmental issues: www.nukewatch.org.
The Institute for Science and International Security is a nonprofit, nonpartisan institution dedicated to informing the public about science and policy issues affecting international security: www.isis-online.org.
The Institute for Energy and Environmental Research provides activists, policymakers, and the public with understandable and accurate information about energy and environmental issues: www.ieer.org.
An independent federal agency established by Congress in 1988, the Defense Nuclear Facilities Safety Board provides safety oversight of the nuclear weapons complex operated by the Department of Energy: www.dnfsb.gov.
Tri-Valley CAREs is a California-based nuclear watchdog group: www.trivalleycares.org.