I’ve decided to start a short series on the different types of energy sources in use and their pros and cons. First, we’ll start with perhaps the most controversial energy source: nuclear. If you remember my Basic and Background Science post on Atoms and Elements, then you know that an atom is composed of a nucleus of protons and neutrons surrounded by an electron cloud. Isotopes of an element occur when the atom has more or less neutrons than normal. Nuclear energy is caused by splitting uranium isotopes within a reactor core.1
Called fission, this process can be used to produce steam, which nuclear energy plants use to spin a turbine, producing electricity. Uranium is present in two forms, Uranium 235 (an isotope) and uranium 238. During an induced nuclear fission reaction, a neutron is fired at an atom of Uranium 235, creating Uranium 236, an unstable isotope that quickly splits into smaller elements. This splitting releases energy in the form of heat.
(image: reference 2).2 Nuclear reactors both contain and control nuclear chain reactions. Within the reactor core is both the fuel (contained in fuel rods) and a neutron source. Heat produced by the nuclear splitting reaction is transferred from the fuel to the turbine by a coolant that runs through the core. The turbine then uses the heat to spin, generating electricity. For a more in-depth, but still simple explanation of a nuclear plant system, look at https://whatisnuclear.com/articles/nucreactor.html.
While we know nuclear energy can be used to produce electricity, we also tend to think of nuclear bombs, as well as nuclear plant meltdowns that have occurred, such as in Fukushima, Japan in 2011 and Chernobyl, Ukraine in 1986. While many focus on the extreme examples of disasters, proponents of nuclear energy encourage its use because of its 24-hour, clean air electricity production.
Clean: Generating nuclear energy requires processes upstream and downstream that utilize fossil fuels. While this produces some greenhouse carbon dioxide emission, it’s estimated to be only around 1/100th of the amount produced when using fossil fuels as primary energy.3
Constant Energy: nuclear energy isn’t dependent on the sun, or wind, so it could be produced even on cloudy, windless days, an advantage over solar and wind power.
Potential disaster: There is a lot of potential danger with a nuclear fission reaction. Chernobyl was evacuated and will be unlivable for 20,000 years. Two died in the explosion, and over 100 were exposed to enough radioactivity to be diagnosed with acute radiation syndrome. This disaster was attributed to flawed reactor design combined with human error. Proponents of nuclear energy are quick to point out that human error, rather than faulty design or process, is the cause of most nuclear reactor disasters, but that’s hardly reassuring. At any energy-generating plant, there will be a mistake made eventually. It’s the potential for disaster and destruction resulting from that mistake that should be taken into consideration before employing any type of energy production.
Waste: Radioactive waste is created through some of the processes of nuclear energy generation, such as the nuclear fuel cycle, and from spent fuel rods.3 This waste is first stabilized and then put into a strong, resistant materials, such as concrete and stainless steel cylinder that is then sealed. Typically these are placed underground. The radioactive waste will decay over time, but on a very long timescale of thousands of years. While studies have evaluated the effect of nuclear waste in a time period of 100 years, given the half-life of the waste materials, effects could extend past 100 years. With developing technologies, part of this waste can be recycled. However, even if the process is refined to have small amounts of waste, the cumulative mass of that waste will not be inconsequential.
Uranium Availability: It’s estimated that there is enough usable uranium to power nuclear energy for the next 85 years, if consumption rates and production processes remain the same.4 However, better practices for utilizing the uranium will be more efficient, allowing the uranium to last longer. Also, methods of using Thorium, an element 3 times more abundant than Uranium), for nuclear energy are being developed, as well as technologies that can use spend nuclear fuel, essentially recycling the Uranium or Thorium used. Recycling the material used would also decrease nuclear wastes. With these developing technologies, it’s estimated that there would be fuel materials for nuclear energy production for thousands of years.
- FAQ About Nuclear Energy. NEI. Accessed 28 July 2017. https://www.nei.org/Knowledge-Center/FAQ-About-Nuclear-Energy
- Spinka, K. The Future of Nuclear Energy: Forbidden Joules. Yale-New Haven Teachers Institute. 2016. Accessed 28 July 2017. http://teachersinstitute.yale.edu/curriculum/units/2011/4/11.04.05.x.html
- The Challenges of Nuclear Power. Nuclearinfor.net 2017. Accessed 28 July 2017. http://nuclearinfo.net/Nuclearpower/TheRisksOfNuclearPower
- The Benefits of Nuclear Power. Nucleoinfo.net 2017. Accessed 28 July 2017. http://nuclearinfo.net/Nuclearpower/TheBenefitsOfNuclearPower