The maintenance of the non-proliferation regime is hampered by objective or artificial contradictions. The non-proliferation regime includes different aspects:
political (treaties, agreements, sanctions)
economic (fuel price, verification and security costs)
technological (proliferation resistance)
control (verification and inspection)
None of these aspects alone can ensure non-proliferation. It would be naïve to believe that, for example, some technology can guarantee non-proliferation and rule out the threat of nuclear terrorism.189 However the successive phase-out of the most hazardous technologies would certainly facilitate non-proliferation.
Uranium enrichment to weapons grade is the most hazardous technology. Most of the separation work is spent on the enrichment of natural uranium to the power reactor grade. Further enrichment to the weapons grade does not require modifications in technology or equipment and does not radically increase the costs. The cost of source uranium is small compared to the total cost of weapons development and it is therefore possible to use uranium from low-grade or alternative (even seawater) deposits. The complex needed to obtain weapons-grade uranium for a limited number of nuclear devices does not require enormous construction and can be arranged secretly. Weapons-grade plutonium can be obtained by replacing a number of standard fuel assemblies in a power reactor, by assemblies with natural or depleted uranium, or by extracting plutonium from fuel with the limited exposure period. It would seem wise to give more care to the proposals that could help rule out or at least strongly restrict the use of uranium enrichment and back-end technologies in the future (BREST type reactors, molten-salt reactors). Unfortunately the bounds between military and civil technologies are seen to be only quantitative, not qualitative. They can easily be overstepped if verification measures are disabled.
For terrorist groups interested in nuclear weapons, the transportation of the fresh and spent nuclear fuel of power reactors may become the most attractive stage of the nuclear fuel cycle. It is comparatively easy to finish the former and to extract plutonium from the latter. Transportation is much more difficult to secure than stationary objects. Recently the feasibility of using medium- and low-power reactors to supply small countries or hard-to-reach regions with energy has been widely discussed. Such stations may be very attractive to nuclear terrorists. Radioactivity which would accumulate with time due to operation would protect these stations against intrusion and theft, but during the start-up period this barrier would be absent.
Why do countries developing nuclear power aim to have a complete nuclear fuel cycle? There are both political and economic reasons. What attracts them is the independence of nuclear fuel supplies and the possibility to fabricate fuel at a price that would be lower than that in the highly-monopolized world market. A complete domestic cycle is estimated to become economic from a total nuclear power of 20 gigawatts, and changes in the cost of natural uranium and fuel cycle improvements may reduce this threshold. Some countries are certainly interested
The threat from low-enriched uranium (LEU) or spent nuclear fuel (SNF) usage can not be eliminated by simple organizational means. International Atomic Energy Agency (IAEA) control is not an absolute barrier although it hinders illegal LEU and SNF usage. Significant efforts by countries with nuclear power industries as well as those of the world community are required to eliminate these threats.