So the nuclear share in electricity output would decline from its present 20 percent, but not disappear. Worldwide, the aggressive nuclear programs in Asia and France would offset retirement of nuclear plants elsewhere in Western Europe. Global nuclear power capacity is forecast to grow from 330 gigawatts now to 340 gigawatts in 2010. Thomas Cochran of the Natural Resources Defense Council discussed the proliferation concerns that nuclear power presents. The unanimous opinion of the arms control and weapons design communities is that the main constraint on a country's ability to produce nuclear weapons is the availability of fissile material, that is, plutonium or highly enriched uranium.
Plutonium is a by- product of nuclear power production.
Four countries the United Kingdom, France, Russia, and Japan have made heavy commitments to recycling and reprocessing plutonium from nuclear power reactors, to reuse as reactor fuel. Unfortunately, even a small amount of plutonium from a civilian reactor is sufficient to make a nuclear weapon. The existing international control regime over nuclear material is not adequate to monitor plutonium flows, much less to prevent diversion to weapons use. Cochran argued for an international agreement to forego production, separation, and isotropic enrichment of weapons-usable nuclear material. There is broad consensus that the United States must maintain a military readiness to defend oil supplies if needed.