A nuclear power plant complex in Cattenom, France. (Photo: By Stefan Kühn, from Wikimedia Commons)
As Tom Yulsman points out in his Feb. 5 posting, the tight connection between nuclear power and nuclear weapons is seriously underplayed and often ignored in discussions about the so-called “need” for nuclear power to help meet energy demand while addressing global warming concerns. (Issues including accidents, terrorism, high-level nuclear waste disposal and economic costs are also important, but I won’t deal with them in this brief commentary.) While Tom mentions the concern over plutonium, which I’ll return to momentarily in responding to the questions from the commenter on the Feb. 5 post, remember that the convergence between nuclear power and weapons occurs at two points in the nuclear “fuel cycle” — the cradle-to-grave process beginning with uranium mining and ending with nuclear waste or incredible explosions.
The first power-weapons crossover comes during uranium “enrichment,” after uranium ore is milled to extract uranium in the form called “yellow cake” that is then converted to uranium hexafluoride gas. Enrichment of the gas means increasing the amount of the fissile uranium-235 isotope, which comprises 0.7 percent of natural uranium, to the 3-6 percent needed to make fuel rods for commercial nuclear reactors. The same centrifuges (the modern technology of choice) that separate the U-235 from the U-238 can be kept running until the percentage of U-235 reaches about 90 percent and can be used for the kind of nuclear bomb that destroyed Hiroshima. Enrichment — low for nuclear power plants and high for bombs — is at the heart of the current controversy over Iran’s plans and capabilities.
The second power-weapons crossover comes when low-enriched uranium fuel is burned in nuclear reactors, whether military, civilian, or dual use. Neutrons produced in the chain reaction are captured by the U-238 to form U-239 then neptunium-239 which decays into plutonium-239, the key fissile isotope for nuclear weapons. Other plutonium isotopes, such as Pu-240, Pu-241, and Pu-242 are also produced. The extent to which the uranium fuel elements are irradiated is called “fuel burnup.” Basically, military reactors designed specifically to produce Pu-239 burn the fuel for shorter periods, a few weeks, before the fuel rods are removed from the reactors in order to minimize the buildup of Pu-240 and other elements. Commercial reactors, aimed at maximizing the energy output in order to produce electricity, burn the fuel for a year or so before the fuel rod assemblies are changed out. The used or “spent” fuel contains higher percentages of the undesirable (for bomb builders) plutonium isotopes. Dual-use reactors, such as the one that caused the Chernobyl accident in 1986, tend toward the shorter fuel burnup times.
The plutonium in the spent fuel is the 20,000 kilograms that the Federation of American Scientists estimates is produced each year by the world’s currently operating 438 reactors. Other sources estimate the amount of plutonium in spent fuel as much higher. For a good description of these issues, see David Albright, et. al., “Plutonium and Highly Enriched Uranium 1996: World Inventories, Capabilities and Policies,” SIPRI, Oxford U. Press, 1997.
Finally, before the plutonium-239 created in nuclear reactors can be used in weapons, it must first be separated from the uranium, transuranics and other fission products. This is done in “reprocessing” plants and is often benignly referred to as plutonium recycling. Currently there are only a handful of commercial reprocessing facilities, the one in France and the one in the United Kingdom having operated the longest. Much of the plutonium extracted by these plants is mixed with uranium and reused for nuclear fuel in commercial reactors. But reprocessing plants also exist in countries using plutonium for nuclear weapons. Thus, North Korea, the most recent country to join the nine-member nuclear weapons “club,” made weapons through its reprocessing facility.
The fact that a country like North Korea could accomplish the manufacture of nuclear weapons should give pause to those who advocate nuclear power plants as an answer to global warming. A plutonium economy and/or the presence of uranium enrichment facilities in many nations around the world are dangerous prospects. Even accepting the arguments that life-cycle analysis of nuclear plants — which takes into account the emissions from mining, construction and so forth — puts them on a par with renewable energy sources in terms of greenhouse gas emissions doesn’t overcome their disadvantages. And the assurance from nuclear advocates that the next generation of plants (Generation IV, still under development) will be more “proliferation resistant,” isn’t comforting given the technologists’ track record. And that still would be a long way from proliferation proof.
Both global warming and nuclear power pose risks to the world. But there are other ways to address the former without the nuclear weapons proliferation made possible by the latter. Keep in mind that nuclear power is the only energy source associated with weapons of mass destruction.