Fallout
Strontium-90
The years following World War II saw rapid development of nuclear weapons, first by the United States, and then, with about a five year delay, by the Soviet Union. Testing of these A-bombs and H-bombs in the atmosphere produced "fallout", that is, radioactive elements dispersed through the upper atmosphere, settling down later at points far from the test site. In widespread protests, citizens expressed concern at the presence of radioactive elements such as strontium-90 (9038Sr). This isotope, with a 30-year half-life, is chemically similar to calcium, and so was incorporated at increased levels in dairy products at the market.
Although President Eisenhower, in the 1950s, initially favored an international ban on all nuclear testing, many in the U.S. believed that the Soviets could not be trusted. Above ground tests could be monitored, since a nuclear explosion would produce detectable radioactivity in the atmoshere, but the Soviets could cheat by testing in underground caverns.
The Limited Test Ban Treaty
Thus the first arms control measure was the Limited Test Ban Treaty, ratified in 1963, which prohibits testing in the atmosphere, in outer space, and under water. Underground testing continued through 1992, when President Bush ordered a moritorium on testing. This moratorium has been observed by both Russia and the U.S. since. Although testing underground was supposed to prevent the release of radioactivity to the environment, it has been learned recently that Soviet tests in Kazakhstan created large fissures in the earth's surface, and many cases of radiation-induced disease are documented among the population in that region.
Purposes of testing
Testing continued between the 1960s and the 1990s for a number of purposes:
- To periodically check the function of existing types of weapons in the stockpile; to verify that deterioration does not take place over time.
- To develop new types of weapons: for example, weapons that require less fission to produce fusion, or weapons that are smaller and lighter with the same yield.
Threshold treaty
The U.S. in 1974 negotiated and signed the Threshold Nuclear Test-Ban Treaty, prohibiting nuclear explosions greater than 150 kilotons, even underground. This treaty has never been ratified by the U.S. Senate, and so is not in force.
Comprehensive Test Ban Treaty
But there have consistently been calls for a Comprehensive Test Ban Treaty (CTBT), a ban on all nuclear testing, calls made by non-nuclear nations around the world, and by many citizens and groups in the U.S. and Europe. The argument is not primarily about the environmental hazard, but more political: A nation that maintains the right to test nuclear weapons is saying to the world that these weapons are an important part of its military posture -- that it seriously contemplates the use of nuclear weapons in cases of international tension. This makes it more difficult to persuade other nations to abstain from or curtail their own nuclear ambitions.
Link to the NPT
For many years the issue of nuclear testing was tied to the Non-Proliferation Treaty (NPT): Non-nuclear nations tried to make continuation of the NPT contingent upon progress by the nuclear nations toward a testing ban. At present the NPT has been extended indefinitely. But the lack of a ratified comprehensive test ban continues to make it more difficult for the U.S. to work against nuclear capability for countries like Iran and North Korea, as well as against increased nuclear sophistication in countries like China, India, and Pakistan.
Signing the treaty
During the 1960s and 1970s the U.S. often called for a comprehensive test ban, with a verification regime requiring independent inspection of sites in the Soviet Union and the U.S. The Soviets objected, claiming that inspection would be a cover for spying. Later in the 1980s, and especially with the end of the Soviet regime, the Russians urged a comprehensive test ban, but the U.S., under the Reagan and Bush administrations was opposed. President Clinton supported the test ban from the beginning of his administration, and in late 1996 the Comprehensive Test Ban Treaty (CTBT) was completed. As of December, 2000 it has been signed by 160 nations, including the U.S., Russia, England and France.
Weapons development
From the military point of view, the CTBT would restrain the U.S. and other countries from embarking on a number of possible nuclear projects:
- Directed energy weapons: devices such as the x-ray laser, which would focus explosive energy in narrow direction. (This device was a part of the Strategic Defense Initiative ("Star Wars") as originally envisaged by President Reagan in 1983. At the time it was found to be not technically feasible.)
- Enhanced radiation weapons: bombs that produce relatively little blast, but can render an area uninhabitable because of radiation, or can destroy communication/computer systems
- Low weight weapons: further maximization of the ratio of yield to weight, for more effective delivery
- Earth burrowing weapons: designed not to explode until the delivery system reaches a certain point underground. (The purpose would be to destroy underground shelters where an enemy command and control system, and leadership, might be located.)
Opponents of the CTBT would argue that the U.S. should maintain the option of developing these devices to meet future threats. Proponents of the treaty would argue that such developments by one nation would pressure its enemies to do the same, leading to a new arms race and a less stable world.
Verification
One of the issues exhaustively discussed during the CTBT negotiations was verification. Underground tests (except for very small explosives) set off seismic waves (sound waves that travel in the solid rock of the earth) that can be detected thousands of miles away. Thus, the U.S. could monitor whether or not underground testing is occurring in another nation by detecting these waves at seismographic stations outside that nation. Over the years there has been much argument over whether these signals could be distinguished from those caused by natural earthquakes -- but at this point geologists can make this distinction quite confidently.
Under the CTBT a network of 170 internationally monitored seismic stations would be distributed across Europe, Asia, and North America. These would be capable of detecting any explosion with a yield up to 1 kiloton (the equivalent of 1000 tons of TNT), and locating that explosion within a circle of diameter about 35 kilometers. A system would also be in place for inspection of the site of any suspected violation.
Stockpile stewardship
An important part of the discussion in this country has been the need for testing to assure reliability of the existing nuclear arsenal. The U.S. has a "Stockpile Stewardship Program", aimed at maintaining the reliability of its nuclear weapons. Although a single nuclear weapon has thousands of parts, most of these are electrical and mechanical units that are outside of the specifically nuclear explosive. These can be tested separately without detonating the bomb. The core of the fission explosive (so-called "plutonium pits") is believed to deteriorate gradually, but over many decades. Plans are being made now to re-manufacture and certify these without the necessity of explosions. Finally, computer modelling of a nuclear explosion can today provide a means of verifying how a given weapon will behave, without testing.
Rejection by the Senate
The CTBT has been ratified by 69 countries, including Russia, England, and France. It was submitted to the U.S. Senate in 1997, and in October 1999 was brought to the Senate floor. About 50% of the Senate voted in favor of ratification, but a two-thirds majority is required, and so the treaty fell far short of its needed votes. While some senators expressed concern about the verification plan, most of the opposition focussed on the question of testing for assuring reliability of the stockpile. Both sides would agree, I think, that the debate was lacking in depth and thoroughness.
Rejection by the Senate caused considerable dismay in capitals throughout the world, although the impact on the American public was not great. It is possible that ratification will be reconsidered at some point in the future.