Amateur A-Bomb?

The carefully written note contained a message that was frighteningly clear. Unless city officials paid the letter writer $1 million and assured him safe passage out of the country, he would set off an H-bomb in the middle of town. To make matters worse, the note was accompanied by a credible-looking diagram of a thermonuclear weapon. Consulted by city officials, experts at the Atomic Energy Commission refused to say for certain that the would-be bomber was not fully capable of carrying out his threat.

This melodramatic incident was not conjured up by a TV scriptwriter or a science-fiction novelist. It actually occurred in Orlando, Fla., a few years ago. Only competent police work and a slip-up by the "bomber" revealed that he was in fact a 14-year-old high school honors student in science who was bent on nothing more than a spectacular hoax. What made the mischief so chilling was that nuclear blackmail by terrorist or criminal organizations is far from inconceivable. It is quite possible that a simple but devastating atomic weapon could now be made by one or more terrorists without advanced scientific and technical skills.

That is the conclusion of a growing number of nuclear experts. A report prepared for the Atomic Energy Commission and released last week by the Senate Subcommittee on Executive Reorganization labels the nation's safeguards against nuclear theft and blackmail as "entirely inadequate to meet the threat." A study conducted for the Ford Foundation by Atomic Physicist Theodore B. Taylor and Arms Control Expert Mason Willrich makes the point even more strongly. In "Nuclear Theft: Risks and Safeguards," Taylor and Willrich report that amateur bombmakers could probably put together weapons as small as one-tenth of a kiloton (equivalent to the explosive force of 100 tons of TNT). Such bombs, says Taylor, would be powerful enough to topple the twin towers of Manhattan's 110-story World Trade Center or destroy the U.S. Capitol building.

Greatest Deterrent. Physicist Taylor's warning has not been lightly taken; his credentials are impressive. During his seven years at the AEC's Los Alamos Scientific Laboratory, he specialized in the design of compact and efficient A-bombs. Though Taylor admits that the fabrication of such devices is beyond the capability of basement bombsmiths, he feels that the manufacture of less sophisticated and powerful weapons is not.

Until recently, the greatest deterrent to amateur bombmaking was the scarcity of the key ingredient. Both weapons and nuclear reactors need fissionable material to sustain a chain reaction --the familiar energy-producing process in which tiny, fast-moving neutrons released by the breakup (fission) of one unstable atom smash into the nuclei of neighboring atoms, causing them to split. The common reactor fuel--which was also used in the bomb that leveled Hiroshima--is a fissionable isotope of uranium called U-235. But U-235 accounts for only about one out of every 140 atoms of uranium in nature, and it takes enormously sophisticated methods to separate even a small amount of the isotope from the more common, nonfissionable uranium 238. Most of today's so-called light-water reactors run on a mix of only 3% U-235, which is far below the enrichment level needed by weapons makers. In the future, plutonium, which is far more efficient--and lethal--will largely replace U-235 as reactor fuel.

Easy Hijacking. The first man-made element ever to be manufactured in a quantity large enough to be seen with the naked eye, plutonium was used in the more devastating A-bomb dropped on Nagasaki. It is also a natural byproduct of the 20th century alchemy that occurs inside all nuclear reactors using uranium. But plutonium is difficult (and thus expensive) to handle; it is so toxic that the inhalation of only a few specks of dust is sufficient to cause cancer.

Until recently, there has been little peaceful use for plutonium, and most of the small amounts produced by utility companies has been either stockpiled or used for research. But as methods for using this material are perfected, plutonium will become an increasingly common reactor fuel. As a result, traffic in the stuff will swell. It will be shipped from processing plants to fabricating plants (where it is made into fuel rods that are unusable for weapons), to nuclear installations, and then back again for reprocessing. In addition, the AEC's highly touted "breeders," a new generation of reactors that produce considerable amounts of plutonium, will increase the "ploot" supply. According to some estimates, by the year 2000 the annual production of plutonium in the U.S. will be 600,000 Ibs.--and most of this will be in commercial rather than Government hands.

With so much of the material around, terrorists might not find it too difficult to get their hands on it. Hijacking could be relatively easy even though shipments are accompanied by armed guards. The AEC is tightening its security measures against theft, but some weapons-grade material is lost during processing and merely written off as MUF (materials unaccounted for). If an employee-conspirator decided to accumulate a critical amount of plutonium by helping himself to a little MUF at a time, the loss might never be detected. Weapons-grade material could also be taken by force in a direct assault on a storage, fabrication or reprocessing plant. Though protected by fences, electronic devices and armed guards, the plants are still far from impregnable. Last fall, for instance, the Government Accounting Office showed two of these buildings to be security nightmares. Among its findings: doors without alarms, gaps under fences, flimsy sheet-metal walls, plastic skylights that could be opened in one minute. They also found inadequate liaison with local authorities: when police were alerted in one test, they went to the wrong location 14 miles away.

Easier Than Heroin. Taylor, for one, is convinced that terrorists could actually fashion the stolen material into a bomb in a matter of weeks. To achieve the biggest bang, the bombmakers would probably choose to convert their purloined material into a metal. Plutonium and U-235 can be transported as compounds that do not readily lend themselves to the making of the most efficient weapons, but the techniques for purification are, says Taylor, in some respects no more difficult than refining heroin in an illicit laboratory.

As for the actual manufacture of the bomb, the basic information can be gleaned from any number of public documents, some of them published by the AEC. Essentially, all that is needed to achieve a blast is to bring together a sufficient amount of properly shaped fissionable material fast enough to initiate a massive chain reaction. To do that, the Hiroshima bomb used the so-called gunbarrel technique: both ends of a heavy metal pipe were stuffed with U-235 and the charge at one end was used as a projectile. To detonate the bomb, the U-235 projectile was hurled by conventional explosives down the barrel and into the mass at the other end. The density of the material in the combined masses of U-235 suddenly increased enough so that the fast-moving neutrons triggered a chain reaction and the bomb exploded. The Nagasaki bomb used a more efficient method: a hollow sphere of plutonium was enclosed by shaped explosive charges. When the explosive was detonated, it sent much of its force inward, crushing the plutonium into a solid ball, a "supercritical" mass that released even more energy than the Hiroshima bomb. With the proper explosive and some plutonium fashioned into the proper shape, a skilled amateur might well produce a powerful weapon.

To keep such potentially murderous materials out of the wrong hands, the AEC study recommends the establishment of a federal nuclear protection and transportation service, stronger links between the AEC and such intelligence-gathering agencies as the CIA and FBI, and tougher testing of the security measures taken by such "nuclear licensees" as fabricators, processors and storage depots. These measures could make it more difficult for do-it-yourself bombers. But perhaps no system is proof against Murphy's Law, which holds that if anything can possibly go wrong, it will. Back in the early 1950s, a routine inventory revealed that a U.S. A-bomb was missing, and no amount of searching succeeded in locating it. As the military sweated, a senior officer happened to visit a dump on a military base. He strolled between piles of discarded A-bomb casings that were about to be offered for sale as scrap. There among the rejects he found the missing bomb.

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