As I mentioned in “What’s the Alternative?“, Nuclear accounts for 6% of world wide energy production, the largest source after all the various fossil fuels. Nuclear is not a form of renewable energy, but it is a potential alternative to fossil fuel. Nuclear has a bad reputation, primarily due to potential hazards of the power plant and the waste, as well as the fear of nuclear weapons. I don’t believe these issues are sufficient to rule out a nuclear future.

Modern day nuclear energy utilizes a controlled fission reaction to generate heat. The heat is used to boil water, generating heat. The heat is used to drive a steam turbine which generates electricity. Fission is the splitting of an atom caused by striking it with neutrons. The splitting of the atom releases energy and additional neutrons which may strike other atoms, causing a chain reaction. The chain reaction is controlled by using materials that absorb (cadmium) and moderate (water) neutrons. A diagram of a light water reactor (LWR) can be seen below.

Thermal Reactor Diagram [Source: Wikipedia]

The most common fuel source for nuclear fission reactors is uranium-235. Naturally occurring uranium is less than 1% uranium-235, the rest being uranium-238. To maintain a sufficient chain reaction, most uranium is enriched to 3-4% uranium-235. One gram of uranium-235 has the energy potential of 3 metric tons of coal [Source: IEER]. The US currently produces 20% of its energy using nuclear power and France uses nuclear for 80% of its power. According to the Energy Blog, China is planning to quadruple their nuclear power by 2020.

One of the primary concerns with nuclear power plants is safety. There have been accidents at plants resulting in radiation contamination. The worst commercial nuclear reactor accident in the US, Three Mile Island (1979) is said to have produced less than 100 millirems of radiation exposure on site (less than annual exposure due to natural sources) and 1 millirem of exposure to nearly 2 million people ( a chest X-Ray is about 6 millirems). [Source: US Nuclear Regulatory Commission]

The destructive power of nuclear weapons also feeds the fear of nuclear power generation. A nuclear weapon utilized an uncontrolled chain reaction of weapons-grade uranium. Weapons-grade uranium is enriched to over 85% to achieve such a devastating result. Enriching uranium to weapons-grade level is not a trivial process, although knowledge of the enrichment process for nuclear power generation could lead to the knowledge of achieving weapons-grade uranium. Or so it is feared.

Uranium is a fairly common material in the Earth’s crust. While uranium-235 produces much more energy than coal, a lot of uranium ore is needed to produce the necessary uranium-235. However, many studies have shown the indirect emissions from nuclear power generation are many times less than fossil fuel plants. Nuclear generation does not produce most of the pollutants associated with the combustion of fossil fuels. Spent rods can be reprocessed to recover 95% of the remaining uranium, but the technology to achieve this is still in it’s early stages. France, the leading reprocessing country, recovers 28% of their spent fuel. The rest is placed in secure storage with the hope that the technology will arise which can reprocess the material further.

Nuclear technology continues to improve. Continued improvements in reactors and reprocessing will make nuclear even more viable. Research is still ongoing in the ever-elusive area of fusion reactors, which theoretically use and produce fairly harmless material, but they are not yet viable. In the mean time, concerns for safety will most likely relegate nuclear to a small role in world-wide energy production.