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| Fig. 1: Proposed Design for Yucca Mountain, Nevada (Source: Wikimedia Commons). |
Most people define nuclear waste as fuel that has been used in a reactor once. It is found in solid form, and continues to be useable for energy extraction for up to five years. [1] Nuclear waste is not produced at nearly the same rate as any other form of energy production, such as coal plants. In fact, generating enough electricity for use by one person produces only 30 grams of spent fuel in a year. [2] In total, US nuclear reactors produce about 2,000 metric tons of waste a year. [3]
There are three types of nuclear waste: high-level, intermediate-level and low-level waste. High-level waste has the highest radioactive content at approximately 95%. Intermediate-level waste makes up about 7% of all waste and usually consists of used filters, steel components from the reactor and some effluents used in reprocessing. Low-level waste includes lightly-contaminated items such as work clothing and tools used from operating nuclear plants; this type of waste makes up the bulk of waste. [2]
Low- and medium-level waste is generally easy to dispose. If not disposed of like normal trash, it is safely transported to one of four repositories in South Carolina, Utah, Washington or Texas. [1]
High-level used fuel is extremely hot and radioactive, so it must be stored in a concrete and steel pools between 2-5 years. [1] Once cooled, the waste can be safely transferred and stored using the dry cask method for at least a century. Steel containers encased in concrete immerse radioactive rods in helium or another inert gas. This is not a long-term solution, and costs upwards of $1 million per cask. More importantly, radiation still escapes the casing at a rate of 1 millirem of radiation per hour and warms the outside of the 100-ton concrete to about 90 degrees Fahrenheit. While physicists celebrate the success and stability of this method, politicians and environmentalists decry the dry cask method because it could become an easy target for terrorists or a potential environmental catastrophe if breeched. [3]
A more permanent solution for all of the spent fuel from US nuclear reactors is Yucca Mountain in Nevada (see Fig. 1). Since 1987, this mountain has been a planned project by the US government and Department of Energy, both of whom have collectively invested over 11 billion dollars to build a mine deep within the mountain to prepare it for storage. [3] Yet, this solution has many other disadvantages. Critics point out that the site's close proximity to fault lines, given recent earthquake damage to buildings near Yucca, makes it an unsuitable location. In addition, water flowing through the rock will inevitably transfer radioactive waste into the soil or drinking water. Despite these obvious flaws, the amount of time and energy devoted to preparing Yucca makes the US government less eager to seek out an alternate solution. [3]
Countries like France and Russia recycle spent nuclear fuel by extracting the necessary elements still capable of producing new fuel, yet this is rarely used as a method of dealing with used fuel in the United States. [2] However, there are recent plans for advanced reactor designs that would allow sites to run on used fuel sometime in the near future. [1]
One such idea involves fast-breeder reactors. They use leftover plutonium to generate electricity and continue to the process of nuclear fission, which in turn produce more plutonium. While theoretically hailed as an inexhaustible source of energy capable of making reactors self-sustainable, fast-breeder reactors have not worked in practice. Their complexity and costliness make them susceptible to leakages and shut downs, and as a result they are just not economical at the moment. More importantly, even if this method were to eventually work, it offers no solution to the thousands of tons of nuclear waste still in need of permanent storage. [3]
With the future of nuclear waste disposal still highly uncertain, the easiest and safest way to store used fuel is dry casks at sites made of concrete and steel and heavily armed with security officers. As universities, governments and research centers dump billions of dollars into finding alternate methods to deal with radioactive residue, all that can be done right now is hide it deep within the many new armed concrete fortresses scattered across the country.
© Alexandra Hellman. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] S. B. Ostarić and F. Neubauer, "Principle Rock Types For Radioactive Waste Repositories," Rud Geol. Naft. Zb. 24, 11 (2012).
[2] "Radioactive Waste: Production, Storage, Disposal," US Nuclear Regulatory Commission, NUREG/BR-0216, May 2002.
[3] D. Biello, "Spent Nuclear Fuel: A Trash Heap Deadly for 250,000 Years or a Renewable Energy Source?" Scientific American, 28 Jan 09.
