Nuclear waste is the hazardous by-product of nuclear fission and consists of several radioactive elements. These by-products are formed by the splitting of Uranium (U-235) and Plutonium (Pu-239) nuclei. Each element has its own half-life i.e. the time taken for the element to loose half its radioactivity. The half-life can vary from a day to five billion years. Generally elements with lower half-lives have a greater radioactivity. [1]
There are three categories of nuclear waste: low-level waste, intermediate-level waste and high-level waste. Low- level waste includes material with very short-lived radioactivity and similar to the waste of any other industry. Intermediate-level waste has a hazardous amount of radioactivity but do not require to be cooled before it is stored. [2] High-level waste accounts for 95% of radioactivity and is generally extremely hot. The annual low and intermediate-level waste production is 200,000 cubic meters while the high-level waste production is 10,000 cubic meters. Yet the hardest part is the disposal of the high-level waste. [3]
The waste first undergoes processes such as vitrification, ion exchange and synroc, which are necessary in the short term but not sufficient for a long-term treatment. The long-term management techniques include:
This method involves storing the waste in a dry-cask concrete cylinder along with an inert gas. It is inexpensive and can be implemented adjacent to the plant. This method has not had any issues since it was first implemented in 1986. [4]
This method involves mining underground into stable geological formations and storing the waste there. The aim is to go as deep as 500 to 1000 meters and completely isolate the radioactive waste. A variant of this technique is to store the waste beneath the ocean surface. [5]
This method involves taking the nuclear waste produced by the reactor and allowing it to go a further nuclear process to change into a less radioactive element. Transmutation cannot eliminate the need for isolated waste storage but it can reduce the length of the radioactivity of the waste. [6]
The method involves using the waste in other useful processes. Countries such as France and UK have been implementing this technique for decades. However the process is costly and technologically challenging. [7]
This method involves launching the waste into space thus eliminating all risk of the radioactive leak. However this could be susceptible to launch failures, which would have a drastic effect. Furthermore this method can prove to be very costly. [8]
© Shiv Parekh. 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] R. C. Ewing, "Nuclear Waste Forms for Actinides," Proc. Natl. Acad. Sci. 96, 3432 (1999).
[2] P. Vankerckhoven, "Radioactive Waste Categories - Current Powition (1998) in the EU Member States and in the Baltic and Central European Countries," European Commission, EUR 18324, 1998.
[3] Disposition of High-Level Waste and Spent Nuclear Fuel: The Continuing Technical and Societal Challenges (National Academies Press, 2001).
[4] "Backgrounder on Dry Cask Storage of Spent Nuclear Fuel," U.S. Nuclear Regulatory Commission, February 2013.
[5] "Geological Disposal of Radioactive Wastes Produced by Nuclear Power," European Commission, EUR 21224, 2004.
[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] A. Andrews, "Nuclear Fuel Reprocessing: U.S. Policy Development," CRS Report for Congress, RS22542, 27 Mar 08.
[8] R. E. Burns et al., "Nuclear Waste Disposal in Space," U.S. National Aeronautics and Space Administration, NASA Technical paper 1225, May 1978.