Armageddon Science (10 page)

For the next two weeks, the world teetered on the brink of nuclear war. President John Kennedy described the situation in an address to the nation as “standing before the abyss of destruction.” The United States set up a naval blockade of Cuba. Some of the President’s military advisers were recommending an immediate preemptive nuclear strike. If it were left to the Russians to attack first, it would be too late.

By the second week of the crisis, the United States was on DEFCON 2, the last state of alert before out-and-out war. Extra bombers took to the skies. In a situation that must have seemed like a living nightmare, the military command prepared to send out the messages that would precipitate nuclear Armageddon. In the end, on October 28, Soviet premier Nikita Khrushchev took a step back from disaster and announced that the missiles would be withdrawn. (The next year, the United States removed some missiles from Turkey that were equally close to the Soviet Union, though this was far less publicized.)

Although nothing came as close as this again, it is sobering to note that the Soviets also set up a doomsday system in the 1970s, designed to cope with the event of an overwhelming attack on the USSR. The idea, much like the hypothetical cobalt bomb doomsday device, was that if the Soviet Union were attacked, retaliation would be so swift and complete that there would be nothing left to fight over. This retaliation would happen even if the conventional Soviet command and control structure was wiped out.

This Perimetr system used a network of computers to assess the situation during a nuclear attack. Should communication with the Kremlin be lost, the system was capable of autonomously issuing the orders to retaliate massively. There was no requirement for human intervention, beyond a confirmation from a relatively junior level. Frighteningly, as far as we are aware, this system, dependent as it is on ancient 1970s computer technology, is still live, still capable of delivering a fatal counterblow to wipe out the Western world.

Despite the end of the cold war, nuclear warfare remains a danger, particularly in tense regions like the India/Pakistan border, and with concerns about development of nuclear weapons in countries like Iran and North Korea, we now also face a more subtle nuclear threat: nuclear terrorism.

The idea that terrorists could bring about nuclear destruction is a horrifying one. There is little doubt that those responsible for the devastation of September 11 would go ahead with a nuclear attack if they were capable of doing so. There seem to be three possibilities for this: building a true nuclear bomb from scratch, obtaining an existing nuclear bomb on the black market, or producing a so-called dirty bomb.

The first requirement to build your own bomb is to get hold of the materials. Occasionally you will see a scare in the press that this might be achieved by the unlikely mechanism of rounding up smoke detectors from stores across the country. Most smoke detectors contain a source of the element americium. Element 95 in the periodic table, americium sits in the detector, beaming out radiation as it slowly transforms to neptunium with a half-life of 432 years. The alpha particles radiating from the americium source (it’s a better alpha source than radium) pass through a small compartment where they ionize the air, allowing a tiny electrical current to cross the chamber. If smoke particles get in the chamber, they absorb the alpha particles before they can create ions, stopping the current flowing and setting off the alarm.

It’s certainly true that americium can be used to produce a nuclear weapon. Assemble enough of that americium 241 and it will go critical. But before any terrorist groups try to corner the market in smoke detectors it’s worth pointing out that it would take around 180 billion of them to have sufficient americium 241 assembled to produce a nuclear device. And even then it wouldn’t be enough to put the detectors together in the same place; you would have to painstakingly extract each of those 180 billion specks of the element and mold them together, an effort that would take thousands of years.

At first sight, a terrorist group building a nuclear weapon from scratch seems fairly unlikely even with more conventional radioactive materials. The resources required to build a nuclear weapon have traditionally been huge. Not only do we have the example of the amount of effort that went into the Manhattan Project during the Second World War; there is also the limited success so far from whole countries that have been trying and failing to join the nuclear powers. What hope could a terrorist group have, where an entire country has failed?

However, terrorists could have some advantages over a legitimate state, in that they could obtain fissile material—most likely plutonium, which is produced by the nuclear industries of several countries—illegally, by theft, rather than attempting to purchase it openly or manufacture it. The construction of a traditional bomb itself requires sophisticated engineering and explosives expertise to get the explosive “lenses” that concentrate the impact correctly if plutonium is used—but it is conceivable that a well-funded terrorist group with access to the right expertise could manufacture a crude weapon.

Although plutonium is probably easier to get hold of illegally, the technical problems of making a bomb operate with it are significantly greater than with enriched uranium. Here, to quote nuclear physicist Luis Alvarez, “if highly enriched uranium is at hand it’s a trivial job to set off a nuclear explosion…. There would be a good chance of setting off a high-yield explosion simply by dropping one half of the material on the other…A high school child could make a bomb in short order.”

While Alvarez was probably exaggerating a little for effect, a bomb based on enriched uranium could easily be assembled in a garage laboratory. Of course this still leaves a terrorist group with the need to get its hands on enriched uranium. As the Manhattan Project and twenty-first-century examples like the Iranian nuclear program have proved, producing this is nontrivial. But enriched uranium exists in a number of countries around the world, some of them more open to black market deals than others—and its very existence makes it a potential target for theft.

However, the one disadvantage the terrorists have is that enriched uranium, unlike plutonium, which is a natural by-product of electricity-generating nuclear reactors, tends to be in the hands of the military. Uranium enrichment is a tricky, expensive, high-tech process, and there is no reason to have the substance unless you are building a weapon. The confinement of enriched uranium to military establishments does mean it is likely to be more securely stored than plutonium. But there is still the potential for terrorist access where military personnel are susceptible to bribes or threats.

On at least two occasions, quantities of around three kilograms of enriched uranium have been seized from individuals from the former Communist bloc who were attempting to smuggle the materials into the West. Remember that there is no other use for this material than for making a bomb, though it would require around sixty kilograms of highly enriched uranium to make a weapon. We have no idea how many such attempts to smuggle the material have got through undetected.

It seems to some analysts more likely that an existing bomb, from the arsenal of the former Soviet Union or from an area with complex politics like Pakistan, could fall into the hands of terrorists. This is a frightening possibility, though there are some safeguards. Most existing weapons, both U.S. and Soviet, have sophisticated mechanisms to avoid their being used by anyone other than their owners. It’s not impossible, but the probability is relatively low. Even so, the chance that terrorists could let off such a nuclear device is one that the U.S. government takes seriously.

In July 2009, the Committee on the Medical Preparedness for a Terrorist Nuclear Event, a group set up by the Institute of Medicine at the government’s request, held a workshop that produced a number of recommendations for coping with the impact of a nuclear blast. Although they are eerily reminiscent of the civil defense instructions from the cold war (put tape on your windows, hide under a table), there are serious suggestions here for coping with a nuclear attack.

The point of this work is to make the public more aware of the nuclear threat and to be more prepared. If a nuclear device explodes without warning, there will be little time to issue instructions. It’s argued that the population, particularly in target cities like Washington and New York, needs to be aware of what actions they should take in the event of an attack.

The report from the workshop describes the impact of a ten-kiloton nuclear device—the scale of device that is most likely to be assembled by terrorists. Almost everyone within a one-kilometer radius of the blast would die—but outside that area there are possibilities for taking defensive action. Depending on which the way the wind is blowing, the fallout from the blast, a rain of highly radioactive rubble and ash, could plume out for miles from the center of the explosion. It’s up to the National Atmospheric Release Advisory Center at the Lawrence Livermore National Laboratory in its California base to predict how the fallout will spread.

It’s impractical to outrun this cloud even in a car, so the best advice seems to be to stay indoors with windows closed, where the exposure will be reduced by the building, and put as much masonry and numbers of rooms as possible between the people and the fallout. The best place to be will usually be a basement, followed by the central core of large buildings. According to the committee, just moving to such a protected spot could reduce the risk of immediate death by between a hundred and a thousand times.

However, a dirty bomb seems a more likely approach for terrorists than either building a true nuclear bomb from scratch or getting hold of an existing nuclear weapon. A dirty bomb uses conventional explosives, but instead of surrounding the charge with a payload of shrapnel from nails or similar chunks of metal, the bomb is encased in radioactive material, producing a fallout effect on the area where it is used.

This would deliver a much lower level of radioactivity than the hypothetical cobalt bomb, or even the fallout from conventional nuclear weapons, but would still cause fear and disruption over a wide area. The big advantage for those planning to use such bombs is the ready availability of radioactive material if they aren’t fussy about the type they use. No longer is the terrorist limited to fissile elements—the dirty bomb could contain a cocktail from many sources.

Radioactive materials are employed widely in medicine, in agriculture, and in industry for applications from radiotherapy to prospecting for oil. There are a good number of materials that have a long enough half-life to stay around and cause problems for months or longer and that pump out the high-energy gamma rays that cause cell damage and hence radiation sickness. As well as cobalt, the likes of strontium 90 and cesium 137 could all be added to the radiation-producing jacket of a dirty bomb.

There is no doubt that a dirty bomb would cause a terrible incident, and would produce deaths and injuries, but it’s probable that the biggest problem it would cause would be fear and disruption. Unlike the fallout from a thermonuclear weapon, a dirty bomb would spread a relatively small amount of radioactive material, and without the devastation of the nuclear explosion, many people would be able to get away before the radiation had a chance to have a serious impact on their health. With a reasonable level of radioactive content it would probably take weeks or months of exposure to provide any significant risk.

However, we can’t ignore dirty bombs as a threat. They would spark a huge amount of fear, and could result in devastating financial costs as areas of a city are forced out of use for many months while they are cleaned up, even though the direct threat of the radiation to citizens is relatively low. To give an idea, the level of radiation envisaged from a typical dirty bomb is comparable to the difference in natural radiation levels between Denver and New York. There
is
a relative health risk because of these natural levels. A few more people will get cancer in Denver as a result of it. But it’s not something we think of in terms mass destruction.

The U.S. government has taken the problems of nuclear terrorism seriously. Original concerns were mostly that the Soviets would smuggle atomic weapons into the United States or that there could be an accident with an atomic weapon, but in May 1974 the government received a first attempt at extortion based on the use of a nuclear device. A letter was sent to the FBI threatening to explode a nuclear bomb in the Boston area if $200,000 was not paid.

The first of many bluffing attempts to extract money, this helped trigger the government to respond; instead of occasionally using experts from the nuclear labs and the Atomic Energy Commission to assess these kinds of threats, the government set up an ad hoc unit that would be drawn when needed to form what was initially called the Nuclear Emergency Search Team, known as NEST.

Later renamed the Nuclear Emergency Support Team, to emphasize a role that was not just about searching for nuclear weapons but also about rendering them harmless should they be discovered, the team continues to be formed at short notice to the present day—for example, being deployed on a precautionary basis at the Beijing Olympics in 2008.

On the whole NEST activities have, thankfully, been drills or in response to false alarms. Apart from advising on appropriate checks and security, the team is often called in to verify the credibility of extortion attempts, many of which have followed the 1974 Boston incident. Usually the extortionists ask for much more cash, but (as yet) the schemes have never involved actual nuclear materials. This emphasizes once again the relatively low chance of the use of nuclear materials by terrorists (or extortionists)—but doesn’t make the vigilance any less necessary.

NEST’s role is not made easier by the need to keep what is happening out of the public’s awareness, to avoid panic, which could easily cause significantly more casualties than (for example) a dirty bomb. Although originally working on a make-do basis, NEST operatives now have access to a wide range of detectors, built into everything from attaché cases to vans, and airborne detectors in helicopters and planes. All these devices are designed to pick up the almost inevitable stray radiation that is emitted in different forms from a nuclear device.