The United States currently has 104 operational nuclear power plants. [1] As part of the nuclear fuel cycle process, radioactive waste is produced that needs to be safely dealt with in order to avoid permanent damage to the surrounding environment. Nuclear waste can be temporarily treated on-site at the production facility using a number of methods, such as vitrification, ion exchange or synroc. Although this initial treatment prepares the waste for transport and inhibits damage in the short-term, long-term management solutions for nuclear waste lie at the crux of finding a viable solution towards more widespread adoption of nuclear power. Specific long-term management methods include geological disposal, transmutation, waste re-use, and space disposal. It is also worth noting that the half-life of certain radioactive wastes can be in the range of 500,000 years or more. [2]
The process of geological disposal centers on burrowing nuclear waste into the ground to the point where it is out of human reach. There are a number of issues that can arise as a result of placing waste in the ground. The waste needs to be properly protected to stop any material from leaking out. Seepage from the waste could contaminate the water table if the burial location is above or below the water level. Furthermore, the waste needs to be properly fastened to the burial site and also structurally supported in the event of a major seismic event, which could result in immediate contamination. Also, given the half-life noted above, a huge concern centers around how feasible it would be to even assume that nuclear waste could simply lie in repository that far below the ground. Concerns regarding terrorism also arise. [3]
A noted geological disposal project that was recently pursued and could possible still be pursued in the future by the United States government is the Yucca Mountain nuclear waste repository. The federal government has voted to develop the site for future nuclear storage. Although the Obama administration has been adamant in stating that Yucca Mountain is "off the table," Congress voted by a margin of 10 to 1 in 2009 to keep funding the project as part of the federal budget. A number of concerns surround this project and the ultimate long-term viability of it are yet to be seen given the political uncertainty surrounding it. [4]
Reprocessing has also emerged as a viable long term method for dealing with waste. As the name implies, the process involves taking waste and separating the useful components from those that aren’t as useful. Specifically, it involves taking the fissionable material out from the irradiated nuclear fuel. Concerns regarding re-processing have largely focused around nuclear proliferation and how much easier re-processing would allow fissionable material to spread. [5]
Transmutation also poses a solution for long term disposal. It specifically involves converting a chemical element into another less harmful one. Common conversions include going from Chlorine to Argon or from Potassium to Argon. The driving force behind transmutation is chemical reactions that are caused from an outside stimulus, such as a proton hitting the reaction materials. Natural transmutation can also occur over a long period of time. Natural transmutation also serves as the principle force behind geological storage on the assumption that giving the waste enough isolated time will allow it to become a non-fissionable material that poses little or no risk. [6]
Space disposal has emerged as an option, but not as a very viable one. Specifically, space disposal centers around putting nuclear waste on a space shuttle and launching the shuttle into space. This becomes a problem from both a practicality and economic standpoint as the amount of nuclear waste that could be shipped on a single shuttle would be extremely small compared to the total amount of waste that would need to be dealt with. Furthermore, the possibility of the shuttle exploding en route to space could only make the matter worse as such an explosion would only cause the nuclear waste to spread out far beyond any reasonable measure of control. The upside would center around the fact that launching the material into space would subvert any of the other issues associated with the other disposal methods as the decay of the material would occur outside of our atmosphere regardless of the half-life. [7]
Various methods exist for the disposal of nuclear waste. A combination of factors must be taken into account when assessing any one particular method. First, the volume of nuclear waste is large and needs to be accounted for. Second, the half-life of nuclear waste results in the necessity for any policymaker to view the time horizon as effectively being infinite as it is best to find a solution that will require the least intervention once a long-term plan has been adapted. Last, the sustainability of any plan needs to be understood. Reducing the fissionability of the material and dealing with adverse effects it can have on the environment and living beings needs to be fully incorporated. Ultimately, nuclear waste is a reality with nuclear power and needs to be properly addressed in order to accurately assess the long-term viability of this power source.
© Subhan Ali. 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] "Annual Energy Review 2009," U.S. Energy Information Agency.
[2] R. C. Ewing, "Nuclear Waste Forms for Actinides," Proc. Natl. Acad. Sci. 96, 3432 (1999).
[3] R. L. Murray and K. L. Manke, Understanding Radioactive Waste (Battelle Press, 2003).
[4] A. Macfarlane, "Underlying Yucca Mountain: The Interplay of Geology and Policy in Nuclear Waste Disposal," Social Studies of Science 33, 783 (2003).
[5] A. Andrews, "Nuclear Fuel Reprocessing: U.S. Policy Development," CRS Report for Congress RS22542, 27 Mar 08.
[6] S. Charalambus, "Nuclear Transmutation by Negative Stopped Muons and the Activity Induced by the Cosmic-Ray Muons," Nucl. Phys. A 166 145 (1971).
[7] J. Coopersmith, "Nuclear Waste Disposal in Space: BEP's Best Hope?" AIP Conference Proceedings 830, 600 (2005).