"The risks of nuclear proliferation--the further spread of nuclear weapons and weapons-usable material, technology, and expertise--derive in part from the technical characteristics of the nuclear fuel cycle and the national and international management of fuel cycle activities. Civilian nuclear power plants themselves are not considered a high proliferation risk because it is difficult to make weapons-usable material from reactor fuel. The principal proliferation risk is that states can use the civilian nuclear fuel cycle as a source for the material, technology, and expertise needed to develop nuclear weapons. A state's intent to develop a nuclear weapons capability can be concealed if its activities otherwise appear compliant with its obligations under the Nuclear Non-Proliferation Treaty (NPT). Creating more effective barriers to the diversion of civilian nuclear programs to military purposes--as North Korea has done and as Iran appears to be doing--is central to current efforts to strengthen the global nuclear nonproliferation regime."
National Defense University: http://www.ndu.edu/