The world’s supply of uranium ore is mined primarily in Canada (40% of world supply) and Australia (20%). Because ore actually contains only 0.3% to 12% uranium, it is processed into a solid cake of 85% “natural uranium” (U3O8), which is a standardized commodity that sells for about $20/kg. Natural uranium is then converted into uranium hexafluoride (“hex,” UF6), in which format it can be enriched. Naturally-occurring uranium contains primarily stable U-238, and less than 1% of the fissile U-235 isotope; enrichment increases the U-235 percentage to between three and five percent. After enrichment, the hex is converted into solid pellets of uranium oxide (UO2), which are sealed inside helium-filled metal tubes and shipped to
Fuel is used for about four years in the reactor until it is spent. Then, it is either reprocessed for reuse, or stored as waste in concrete-lined ponds, pending final storage in a repository. Reprocessing is a controversial practice by which spent uranium fuel is transformed back into fissile uranium oxide (96% of the original waste), fissile plutonium oxide (1%), and “final waste” (3%). Reprocessing is appealing because it greatly extends the life of uranium fuel, resulting is less uranium mining and thus preventing the associated aquifer contamination. So why is the process controversial?
1. Proliferation. Plutonium is the fuel for nuclear weapons, and just a few kilos are required to arm a bomb. While the plutonium generated by reprocessing is not weapons-grade, it could be converted into such form if it fell into ill-intentioned hands. Reprocessed plutonium iseither used by governments for weapons, permanently stored in carefully-monitored
government facilities, or mixed with uranium to make a mixed-oxide “MOX” reactor fuel. The plutonium in MOX is rendered useless for weapons purposes after reuse.
2. Health impacts. Fuel is reprocessed by boiling it in nitric acid, generating significant amounts of sludge that is far more radioactive than the original nuclear waste. Existing reprocessing facilities release massive amounts of radioactive caesium and technetium into the ocean. As a result, concentrations of radionuclides several times higher than maximum recommended amounts can be found in lobsters, mussels, and seaweeds near the power plants. The amount of radioactivity in liquid
wastes stored at reprocessing plants can be up to 100 times the amount released by the Chernobyl disaster; a serious accident at one of these plants would result in more than one million new cancer deaths. Even under normal operations, cancer clusters have developed near many of the plants.
Currently, only France, Russia, India, and Japan reprocess waste, collectively treating about 10% of annual worldwide spent fuel. North Korea may also be reprocessing waste explicitly for weapons development; and the fear surrounding Iran’s plans to develop a nuclear power industry is that it will do the same. The UK is in the process of shutting down its reprocessing plant, and the U.S. shut down its facilities in the 1970s due to concerns about plutonium proliferation, worker safety, and waste generation. However, the U.S. and Russia are now developing a MOX fuel fabrication plant in South Carolina as part of a non-proliferation strategy.
In the 1950s, nuclear power was famously anticipated to be “too cheap to meter” (the then head of the Atomic Energy Commission used the phrase in a speech extolling the promise of the new U.S. nuclear power program). Yet today it is one of the more costly sources of electricity in the U.S. system. Given the affordability of uranium, and the small quantities needed to fuel a reactor, one might reasonably expect the power output to be cheap. However, the cost of managing spent fuel (which has a radioactive half-life of 100 years), the cost of safety monitoring, and the much-higher-than-expected capital costs of building each custom plant have driven the actual cost of power up substantially.
Research and development of next-generation nuclear power plants is ongoing in the U.S. and many other countries. Future nuclear reactors may use naturally-abundant thorium as a fuel, or use faster neutron movement to utilize normally non-fissile U-238. On a more experimental level, research into controlled fusion as an energy production means also continues (fusion
is how the sun produces energy, combining hydrogen to form helium).
Depending on whom you talk to, you will hear that the nuclear powerindustry is essentially “dead,” or that it is merely paused and may see renewed activity in the next few years:
Nuclear power has fallen out of favor...
• No new orders for nuclear plant construction have been placed in the U.S. since 1973
• Most of Europe is in the process of phasing out nuclear power: banning new plants and decommissioning existing ones
• Nuclear plants provide baseload power, but only because they take a long time to ramp on and off, not because they produce cheap power
• The problem of long-term storage problem of radioactive waste has not been solved: Yucca Mountain in Nevada has been designated as the US final repository; but concerns over groundwater contamination remain.
• Nuclear plants are horrific accidents waiting to happen (e.g. Chernobyl), and potential terrorist targets. Japan, for example, had to temporarily close down 17 plants for safety lapses in 2003.
...but still offers benefits to consider.
• Nuclear energy generates no direct air pollution or greenhouse gases (though the fuel mining and fabrication require energy expenditures that do have emissions themselves). If the U.S. were to replace all of its nuclear plants with gas plants, CO2 emissions would increase by more than 1%
• Meeting targets for reducing greenhouse gas emissions may be difficult via energy efficiency and renewable power development alone
• Until a new “surprise” technology appears, nuclear power can solve the problem of meeting exponentially-rising demand for electricity in the face of finite oil and gas supplies
• With respect to cost, France for one was able to set up its nuclear sector to produce cheap electricity by adopting just one type of nuclear technology for all of its plants