Under a cloud

By Charles Seife in Washington DC and Michael Day The latest attempt to halt the spread of nuclear weapons, the Comprehensive Test Ban Treaty, lies dead on the floor of the US Senate. The CTBT, created back in 1996 to stop nuclear weapons proliferating throughout the world, still needed to be signed by another 18 countries—including the US—before it came into force. The US rejection effectively kills the agreement. Republicans who dominate the Senate claimed the CTBT was dangerous: not only was it impossible to detect rogue states’ clandestine tests, it threatened the reliability and safety of America’s nuclear arsenal. Dismayed Democrats and international observers dismissed the Senate’s move as reckless party politics. Thirty-two American Nobel prizewinning scientists attacked the logic of the decision, claiming that technology no longer required the US to explode weapons in order to test the reliability of its nuclear arsenal. The first nuclear weapon, the “Little Boy” that obliterated Hiroshima, was merely a modified anti-aircraft gun that smashed two chunks of the heavy metal uranium into each other. When the lumps of metal reached a critical mass, the atoms began splitting at an ever-increasing rate: a fission chain reaction. But more sophisticated and powerful bombs require nuclear fusion, the process whereby the nuclei of lighter atoms, such as hydrogen, stick together. It’s much harder to achieve than fission, because there’s no chain reaction to do all the work. Nevertheless, the US managed it in 1952, when it detonated the first hydrogen bomb. This redirected the radiation from an atomic bomb “primary” onto a flask full of deuterium (heavy hydrogen) to achieve fusion. At about 10 megatons, this was some 750 times more powerful than Little Boy. This hydrogen bomb and its ever more sophisticated descendants have required extensive testing as part of their development. Thus, the CTBT would theoretically have prevented nations like India and Pakistan from developing more powerful and more reliable weapons, and prevented rogue states from starting modern nuclear programmes. However, opponents of the CTBT say that if you want to test a weapon for safety (shooting a bullet into it and ensuring that it doesn’t blow up) or reliability (letting it sit in a hangar for 30 years and making sure it will still explode on command), nuclear tests are obviously a boon. But the 32 Nobel laureates noted that there were viable alternatives. Among them is the US Department of Energy’s Stockpile Stewardship Program, dedicated to keeping nuclear weapons safe and reliable without the use of nuclear tests. It has two major tools. The first is hydrodynamic testing, in which engineers check the plutonium part of the warhead. In the second, confinement fusion testing, engineers check the hydrogen component of the weapon. The Stockpile Stewardship Program can’t test a bomb from the explosion of its first stage to the ignition of its second stage. But it can verify that a bomb with a well-understood design is working because all its individual components are in good order. “We understand the weapons very well,” says engineer Frank Von Hippel, of Princeton University’s Program on Nuclear Policy Alternatives. This is why he says that non-nuclear testing is sufficient to ensure that a weapon will perform as advertised. “I think that the Stockpile Stewardship Program is even more than we need for reliability.” Jon Wolfsthal, of the Carnegie Endowment for International Peace in Washington DC, agrees. “The hawkish view is that our weapons will not remain reliable and safe, but they misunderstand that stockpile stewardship is actually working today.” International observers are also unconvinced by the argument for testing. Philip Towle, director of the Centre of International Studies at Cambridge University, says: “They’ve had a very long time to test the reliability of trigger systems, and there are some states like Israel that are at much greater risk from nuclear attack who have not needed to carry on testing.” Another objection by the opponents of the CTBT is the plan’s supposed inability to identify violators. “Well, this is kind of a distortion of the evidence,” says Jeffrey Park, a geophysicist at Yale University. “We do monitor, currently, known test sites at fairly low magnitudes—2.5 or 2 on the Richter scale—and a 1-kiloton nuclear blast is roughly equivalent to a magnitude 4 earthquake. We’ve got a good capability now.” The CTBT would have provided for an improved network of seismic sensors to plug holes in existing coverage. “The idea is not to give a potential tester any wiggle room,” says Park. It is possible that by hollowing out a large cavity, a state trying to evade the treaty might be able to set off a small nuclear blast—less than one kiloton—without being detected. But anyone testing a hydrogen bomb or a boosted weapon would need a yield much greater than that to collect the required data. “We thought you’d be able to detect tests down to about 1 kiloton,” says Von Hippel. “Below that, there isn’t much interesting you can do.” So if the stockpile is safe and geophysicists can detect significant tests, why was the CTBT kicked out by the Senate? Most believe the explanation is largely political, not scientific. The President is a Democrat and the Senate majority is Republican. “Half of the Republicans, really, are very sceptical of arms control,” says Von Hippel. “All of them hate Clinton.” US commentators note that, during the debate on CTBT ratification, Jesse Helms, the far-right chairman of the Senate’s Foreign Relations Committee, thought it relevant to include references to the Monica Lewinsky affair. But what effect will the death of the CTBT have on international security? According to Towle: “The Senate vote certainly makes it easier for the Indians to resume testing if they want. But whether it would tip the balance with a state that is considering the nuclear arena, such as Iran, is less likely.” The coup last month in Pakistan—India’s bitter regional enemy and itself an emerging nuclear power—has fuelled concern over the CTBT’s demise. The new regime in Islamabad, already under international pressure for introducing martial rule, is unlikely to start rattling nuclear sabres—at the moment. Others are more philosophical. L. K. Sharma, London correspondent of The Times of India and an authority on Indian defence and foreign policy, says: “Developing nations do not need encouragement by the US to develop nuclear weapons. If they have the means and desire they’ll do it anyway.” But according to Maleeha Lodhi, Pakistan’s ambassador to the US from 1994 to 1997: “It’s conceivable that before the year was out India and Pakistan would have been signed up.” India has declared a moratorium on nuclear tests. But some Western observers believe that India cannot credibly deliver even small nuclear weapons at the moment. And Pakistan is behind India. It’s distinctly possible that both states (with India taking the lead) may seek to refine their weapons. If Lodhi’s hunch is right, the Senate’s action represents a lost opportunity. But looking beyond domestic politics and the paranoia over warhead reliability, some observers detect more calculated thinking on the floor of the US Senate. There are commercial interests in weapons investment. And John Simpson, director of the Mountbatten Centre for International Studies in Southampton, notes that the ascendant “unilateralist movement” in US politics is talking up the issue of missile defence systems again. The Anti-Ballistic Missile Treaty looks vulnerable. He suspects some right-wingers are looking forward ten years to a time when the US may be in the position to test new devices powered by nuclear explosion. Indeed, senator John Warner, who chairs the Armed Services Committee, says: “Many of the nuclear systems that we developed to deter the Soviet Union are simply not suited to the subtle, and perhaps more difficult, task of deterring rogue states from nuclear, chemical or biological weapons . . . Such weapons do not exist today in the US arsenal.” Helms’s success in having the Arms Control and Disarmament Agency (effectively a watchdog to stop the Pentagon jeopardising international arms control agreements) abolished last year fuels such speculation. If we’re about to witness a new push on the part of the world’s only superpower to subvert science for dubious political ends, it won’t be the first time. In the meantime, according to observers like William Walker of St Andrew’s University:
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