Nuclear proliferation means the uncontrolled spread of the technology, equipment and fissile materials that would alllow national or terroroist groups to fabricate and deliver nuclear weapons.

Nuclear proliferation was more a theory and concern for many years until the revelations in 2003 that Dr. A. Q. Khan, the leading nuclear weapons researcher in Pakistan was singlehandedly suppplying the information and equipment that moved North Korea, Libya and perhaps Iran much closer to their own nuclear arsenal. In exchange for house arrest and a pardon from the government of Pakistan, Dr. Khan's admitted his lucrative 15-year role in spreading nuclear technology. Dr. Khan offerd integrated nuclear information, sourced the centrifuges necessary for enrichment of Uranium to bomb quality and provided essential consulting services. Dr. Khan's motives are as yet unclear: his activities likely generated hundreds of millions of dollars of personal gain but he may well have had an imbedded belief in proliferation as a leveling of national interests and strengths.

Pakistan's Dr. A. Q. Khan

A nation or group seeking to produce nuclear weapons must complete the following basic steps:

• Develop design for the weapon or obtain the design from an external source.
• Produce fissionable uranium or plutonium for the core of the device or obtain this material from an external source. Once obtained, this material must be fabricated into the nuclear components for the weapon.
• Fabricate or obtain from external sources the non-nuclear components of the weapon. These include high explosives and a triggering mechanism to detonate the nuclear core.
• Verify the reliability of all components individually and as a system.
• Assemble the components into a deliverable weapon. The elements of design and fabrication are complex but are publically known.

Many of the requisite activities that must be taken to build a weapon have been provided by Dr. Khan. Detecting the development of nuclear weapons by non-nuclear states or rogue groups depends on information about all of these steps.

Delivery system for a nuclear weapon
(Courtesy of the Department of Energy)

The major barrier to producing a nuclear device is obtaining weapons-grade uranium or plutonium. The International Atomic Energy Agency (IAEA) states that 25 kg of HEU (Highly Enriched Uranium,, > 90% U-235) or 8 kg of plutonium are the minimum amounts required for a 20-kiloton explosion (equivalent to the Nagasaki bomb). However, a group with more sophisticated technology could build the same weapon with as little as 5 kg of HEU or 3 kg of plutonium.

Uranium enrichment is a complex industrial process requiring huge facilities that house sophisticated equipment and consume large quantities of electricity. However experts generally concede that a nation or group that possesses an amount of HEU sufficient to make a nuclear weapon will be able to amass the engineering and scientific skills to actually build the weapon.

Plutonium can be produced in a nuclear reactor by irradiating natural or slightly enriched uranium fuel with neutrons. Recovery of plutonium from the spent fuel is also a complex industrial process. In general, the uranium enrichment route is considered less likely for proliferation than the plutonium option for national states. But there is considerable HEU held by the nuclear powers and those interested in assembling a weapon might well look to gathering HEU from these sources through stealth and bribe and other illegal efforts.

To date, every nation that has developed nuclear weapons has also developed the capability for producing fissile materials. The first five nuclear weapon states (U.S., Russia, Great Britain, France and China) signed the 1968 Nuclear Non-Proliferation Treaty (NPT). Since that time, India, Pakistan, and Israel have developed nuclear weapons, but are not NPT member states. It is thought that Iran, Iraq (until its liberation in2003), Libya, and North Korea are seeking nuclear weapons. Algeria, Argentina, Belarus, Brazil, Kazakhstan, Romania, South Africa, and the Ukraine have all renounced their programs to develop or maintain nuclear weapons. Twenty-one countries with nuclear facilities and a significant industrial base have signed the NPT as non-nuclear-weapons states and have accepted IAEA inspections.

However, the lack of control of fissile materials and the economic conditions in the former Soviet Union have increased the possibility that HEU might be available on the international black market. Several instances involving smuggled plutonium and enriched uranium from the former Soviet Union have been observed since 1994. The United States and Russia have a "blend-down" agreement since 1993 that would render excess HEU incapable of being fabricated into nuclear weapons. This agreement has the United States purchasing from Russia uranium blended to below HEU concentration. The source of the HEU is dismantling of Russian nuclear weapons over a 20 year period. This program was meeting its targets through 2002 but the American Presidential campaign of 2004 urged that the blending of HEU be accelerated.

Complete Bibliography on Proliferation from the ALSOS Digital Library for Nuclear Issues