The most difficult challenge for a country that seeks to build nuclear
weapons is obtaining the necessary highly enriched uranium or plutonium. In addition to access to uranium supplies, this requires considerable industrial and scientific capabilities. Even less developed countries, however, such as China, India, North Korea, and Pakistan, have succeeded by concentrating their resources on this effort and, in most cases, by obtaining help from governments or individuals in more advanced countries. For example,
China’s nuclear weapon program benefited from early assistance provided by the Soviet Union. India’s program took advantage of Canadian and U.S.
assistance provided for peaceful nuclear research, and Pakistan’s program relied on assistance from China, along with technology and equipment secretly obtained from Western European supplier companies. Without such assistance, nuclear weapon programs in these states would have been greatly delayed and might not have succeeded.
A -Enriched Uranium Bombs
Uranium can be enriched using several techniques. The United States nuclear weapons program has relied on the gaseous diffusion method,
invented during the Manhattan Project, in which uranium is transformed into a gas (uranium hexafluoride) and pumped through membranes that permit U-235 atoms to pass through slightly more often than other uranium atoms. By repeating this process through many cycles, concentrations of U-235 can
be increased to the level needed for nuclear weapons. Britain, France, and China also have relied exclusively on the gaseous diffusion method to
produce highly enriched uranium for nuclear weapons. The Soviet Union did so for many years before shifting to the gas centrifuge method.
The gaseous diffusion method uses great quantities of energy. Indeed, during the Manhattan Project, the United States built a hydroelectric dam, under the Tennessee Valley Authority, solely to power the gaseous diffusion enrichment facility at Oak Ridge, Tennessee. A country seeking to develop nuclear
weapons secretly would find it difficult to do so using this method today because the energy requirements would be nearly impossible to hide. Uranium enrichment using high-speed gas centrifuges is far more efficient than gaseous diffusion. In the gas centrifuge process, uranium is also first converted to gaseous uranium hexafluoride. It is then introduced into the centrifuges—rapidly spinning vertical cylinders—where it is swirled at great speed. Under the centrifugal forces created, the bulk of uranium atoms, which are heavier than U-235 atoms, move toward the outside of the
centrifuge, allowing product slightly concentrated in U-235 to remain at the center and be drawn off. By linking the gas centrifuges together in what is known as a cascade, this process is then repeated until weapons-usable material is created. Pakistan relies on this method of enrichment for producing highly enriched uranium for nuclear weapons. It is also used in India and, possibly, North Korea. Iran has also built a centrifuge uranium enrichment facility, which it states is intended for its peaceful nuclear energy program.
Other enrichment techniques are the jet nozzle process, used by South Africa, and the electromagnetic isotope separation process, which Iraq used in its unsuccessful effort to enrich uranium before the 1991 Persian Gulf War. Lasers can also be used to enrich uranium, although to date no country is known to have employed this method for the development of nuclear weapons. In this method, known as laser isotope separation, uranium is transformed into a metal, vaporized, and then targeted with specialized lasers that “excite” U-235 atoms differently from other uranium atoms,
permitting a concentrated product to be collected. The process is considered very difficult technically, but it can be conducted in small-scale facilities that can evade detection by the IAEA or foreign intelligence agencies. In 2004 South Korea acknowledged that in 2000 it had conducted secret laser enrichment experiments, creating a tiny amount of very highly enriched uranium. Because it is very hard to detect and can be extremely efficient,
the laser enrichment method could pose a significant proliferation risk in the future.
B -Plutonium Bombs
The technology to produce plutonium is technically simpler than that needed to enrich uranium. Nonetheless, plutonium production requires the
construction of a series of expensive and relatively complex facilities,
including a nuclear research, nuclear power, or plutonium-production reactor; a plant for the manufacture of uranium fuel or targets; and a reprocessing plant. The United States, the Soviet Union (now Russia), Britain, France, and China all produced plutonium for their nuclear weapons programs, in addition to highly enriched uranium. Plutonium is the principal nuclear weapon
material used in the Indian, North Korean, and presumed Israeli nuclear weapon programs. Pakistan is also believed to produce plutonium for nuclear weapons.
Because reactors and reprocessing plants, as well as large-scale enrichment plants, are difficult to hide, they may be discovered by other countries, which may attempt to halt their completion by diplomatic pressure or by military attack. In 1981 Israel launched a surprise air strike that destroyed an Iraqi reactor, which Israel feared would be used for plutonium production.
Nonmilitary programs for producing electricity using nuclear power reactors may also employ uranium enrichment and reprocessing. Most nuclear power reactors use uranium fuel that has been enriched to 3 to 5 percent, for
example. Today, this material is produced in commercial uranium enrichment plants in Britain, China, France, Germany, Japan, Netherlands, Russia, and the United States. In 2006 Iran declared that its gas centrifuges had enriched uranium to about 3.5 percent. Gas centrifuge enrichment facilities that
produce low-enriched uranium for fuel can be reconfigured to produce highly enriched uranium for weapons.
In addition, a number of countries are currently reusing, or plan to reuse, plutonium produced in nuclear power plant fuel. This requires separating the plutonium from the spent nuclear power plant fuel in a reprocessing facility and then mixing the plutonium with unenriched uranium to form new fuel, which is then used in a reactor instead of low-enriched uranium. Britain, France, India, Japan, and Russia are separating plutonium from spent nuclear power plant fuel.
Countries seeking to produce nuclear weapons must also develop a reliable design for the weapon. With computer simulations and extensive testing of the nonnuclear components, it is possible for a country to develop a reliable design for a fission weapon without the need for a full-scale nuclear
detonation. Some countries also benefit from nuclear weapon design assistance provided by other nations. For example, Pakistan is believed to have received a nuclear weapon design from China in the early 1980s. A senior Pakistani official is known to have provided a copy of this design to Libya and, possibly, Iran and North Korea. A country may wish to forgo a full- scale nuclear test because a test would be clear proof that it was developing nuclear weapons, which, in turn, could lead to international criticism and diplomatic isolation. Israel has adopted this strategy of nuclear ambiguity, as did Pakistan from the late 1980s, when it is believed to have produced its first nuclear weapons, until 1998, when it conducted its first nuclear tests. V -WHY PREVENTS THE SPREAD OF NUCLEAR WEAPONS?
Nuclear war would have devastating consequences. Even a conflict that involved only the use of one or two fission weapons could cause many hundreds of thousands of deaths and destroy the centers of major cities. Large-scale nuclear war, involving the use of hundreds of thermonuclear weapons, could cause many millions of casualties, destroy nations, and permanently affect the global environment. Although some scholars argue otherwise, virtually all governments believe that the spread of nuclear weapons to additional states will increase the likelihood of nuclear war.
Many of the nations that possess nuclear weapons or have sought to develop them have long had regional conflicts with each other. For example, India and Pakistan have had a serious border dispute over Kashmīr, China and India had a brief border conflict, Israel has fought several wars with neighboring nations in the Middle East, and Iran and Iraq fought an eight- year-long war. North and South Korea, now separated by a demilitarized zone, fought against each other in the Korean War (1950-1953). These regional conflicts and other potential conflicts provide the fundamental reason for the international community to seek to halt the spread of nuclear weapons.
The spread of nuclear weapons can also permit aggressor nations to intimidate neighbors and dominate their regions. Iraq under Saddam
Hussein, its former president, is believed to have sought nuclear weapons for this purpose prior to the 1991 Persian Gulf War. In addition, nuclear weapons could be used as a threat by a country seeking to advance a global
ideological cause, such as the spread of radical Islamic fundamentalism. A growing new danger is that a national government, or senior officials within that government, might provide nuclear weapons or the materials for making them to terrorist organizations whose views they shared. While nations differ on the particulars of such dangers, they generally agree that their own
security is best served by curbing the further spread of nuclear arms.
Nuclear proliferation also inevitably increases the risk of accidents involving nuclear weapons—for example, during transport—which could cause great devastation. This risk may be greatest in less technologically advanced countries whose weapons may not include the built-in safety features found in the nuclear weapons of the more advanced nuclear powers. In some
countries, nuclear weapon programs can divert scarce financial and technical resources from urgently needed development projects, a challenge that can be severely worsened for states engaged in open-ended nuclear arms races with rivals.