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| Fig. 1: Yucca Mountain is a location in Nevada that is home to a deep geological repository. (Source: Wikimedia Commons) |
In a world where nuclear energy has become one of the biggest power sources across the world, it is important to understand and develop efficient methods of disposing of the matter once it becomes waste. The main goal when storing and disposing of nuclear waste is to avoid and prevent any type of exposure to any people. The disposal of low-level waste can really be very simple; the process just takes time because the radioactivity of the nuclear waste decays over time. The time it takes for nuclear waste to decay varies because certain elements have different half-lives. For example, Pu-239 has a half life of approximately 24,000 years while the half life of Radium is approximately 1600 years. There are various forms of effective nuclear waste disposal that are already in use, it is just a matter of determining what is the best long term method for disposal.
The main methods of disposal are near surface disposal and deep geological disposal.
Near surface disposal refers to storage units that are found a few tens of meters below the ground level surface. [1] These units are typically used for short term disposal or for waste with half- lives of thirty years or less. [1] Ground level facilities can be found today in the UK, Spain, USA, France, and Japan. Sweden implemented similar facilities but these facilities are found 50m under the Baltic seabed. These facilities are only used for short term periods because in the long term, they are threatened by climate change, specifically glaciation. [1] This factor alone is what potentially makes the idea of solely using deep geological disposal more attractive.
A deep geological repository is a type of facility in the geological substratum which can be sealed and can provide long-term protection for the people on earth as well as protect the environment. [2] These repositories are created with the hope that they will be able to contain the waste passively, which means that there should be no need for supervision. These facilities are designed so that the waste stored within them can decay into harmless substances over long periods of time. [2] The idea for constructing deep geological repositories in has been introduced in Sweden. As seen in Fig. 1, there is also a deep geological repository in Yucca Mountain. One of the most important factors for designing a deep geological repository is identifying an appropriate site for said repository. Even after a site is found, the process of completing the storage of nuclear waste is a long and monotonous one. This process includes the construction, storage, observation and finally sealing of the facility. [2]
Countries that have successfully been able to utilize nuclear energy have found effective ways of storing and disposing of the nuclear waste but not all countries use the same techniques. It is agreed upon by most people that deep geological disposal is the best method to use because of the minimal risk that comes along with it. While near surface disposal is completely safe and feasible, deep geological repositories provide far more protection and provide this protection for much longer periods of time than the near surface facilities are capable of providing. With the effects of climate change rapidly changing the Earth, a decision may need to be made soon considering deep geological disposal as the sole method for nuclear waste disposal.
© Curtis Robinson. 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] I. W. Donald, B. I. Metcalfe, and R. J. J. Taylor, "The Immobilization of High Level Radioactive Wastes Using Ceramics and Glasses," J. Mater. Sci. 32, 5851 (1997).
[2] R. W. Alexander and L. E. McKinley, eds., Deep Geological Disposal of Radioactive Waste (Elsevier, 2007).
