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| Fig. 1: Government Officials Examine Nuclear Containers. (Source: Wikipedia Commons) |
The earth is continuously producing carbon dioxide into the atmosphere from the energy production of fossil fuels and this carbon dioxide will remain for at least one hundred years, causing "global warming" that will increase the temperature of our planet, causing many weather alterations and other environmental disasters. One solution to the issue is to replace and retrofit current technologies with alternate energy sources that have comparable or better performances, but do not emit carbon dioxide. Every form of alternate energy resource has its strengths and weaknesses, its pros and cons but nuclear energy is one option that is clean, efficient, has a reasonable EROI and a good yield. [1]
Nuclear energy is used to generate around 11% of the world's electricity, with almost no greenhouse gas emissions. Nuclear power plants use the heat produced by nuclear fission to generate steam that drives turbines. The largest advantage is that nuclear power plants can run for months without interruption, providing predictable and reliable electricity in a safe and non-environmentally damaging manner. Nuclear fuel can be used in a reactor for several years; the remaining used fuel must either be recycled or stored or got rid of in a careful and strategic manner. A single uranium fuel pellet has as much energy as 807 kilos of coal or 149 gallons of oil. The uranium is converted to uranium dioxide powder, which is pressed into pellets, which are inserted into fuel rods in the nuclear reactor. [2]
There are three levels of nuclear wastes: the low level waste, that makes up about 90% by volume of the waste and 1% by radioactivity and consists of the items like tools and clothing from the operation of the power plant; the intermediate level waste that comprises about 7% by waste volume and 4% by radioactivity and includes used components from within the reactor and some effluents and the high level waste that is about 3%of the waste volume and 95% of the radioactivity. The high level waste is the most significant waste and includes the spent nuclear fuel after it has been used for about three years in the reactor; it can be reprocessed or recycled. High-level radioactive wastes are highly radioactive materials produced as a byproduct of the reactions occurring within nuclear reactors. High-level wastes take one of two forms: "Spent (used) reactor fuel when it is accepted for disposal and Waste materials remaining after spent fuel is reprocessed. Spent nuclear fuel is used fuel from a reactor that is no longer efficient in creating electricity, because its fission process has slowed. However, it is still thermally hot, highly radioactive, and potentially harmful. Until a permanent disposal repository for spent nuclear fuel is built, licensees must safely store this fuel at their reactors." [3]
Intermediate and low level nuclear wastes can be disposed of in repositories that are specially constructed like normal municipal waste sites, closer to the earth's surface but high level waste requires cooling, shielding and storage until they can be suitably disposed. High-level waste can remain radioactive for a very long time and this is the challenge in their disposal. They need to be stored in deep underground facilities that have been engineered to be stable in geological formations. Such facilities do not currently exist but many countries are involved in designing and constructing such a facility because it has been shown to be feasible to construct such a structure. Used nuclear fuel is very hot and radioactive and has to be cooled down, prior to any storing or treatment, and the workers must be shielded from radiation. Dense concrete or steel can perform the shielding while water can do both cooling and shielding. Nuclear energy is not the only industry that creates radioactive waste, others being space research, medical research, pharmacological products, mining, particle science studies and oil and gas research. The management and finally disposal of nuclear wastes by these industries follows a protocol that is standardized and well established. The unique characteristic of nuclear waste that distinguished it from all other types of toxic waste is that the radioactivity decays and reduces until it reaches a value that is much easier to handle and much less difficult for disposal. [4]
Many scientists and environmentalists believe that it is not ethical to burden future generations with the risks associated with underground, untreated nuclear waste. It is irresponsible for countries to produce nuclear waste until a safe, tested strategy has been developed for the permanent treatment of the waste. The government of some countries have been careless in handling this waste and that adds to the concerns that have been voiced by many scientists. This is further complicated by the fact that nuclear wastes may need to be isolated for long periods of time, may be even a thousand years, and it is extremely challenging to ensure a stable monitoring system across several political institutions. Additionally, the geological behavior of the area has to be studied in great detail and predicted over the next hundreds of years. [5]
The U.S government claims that no major accidents have occurred and the probability of a severe nuclear accident is low but this technology has not been regulated. The present design for fuel containers are not adequate to protect the public and impact and test standards can be exceeded in an accident. [6]
© Caleb Kumar. 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] D. Bodansky, Nuclear Energy: Principles, Practices, and Prospects, 2nd Ed. (Springer, 2008).
[2] S. J. Zinkle and G. S. Was, "Materials Challenges in Nuclear Energy," Acta Mater. 61, 735 (2013).
[3] B. L. Cohen, "High Level Radioactive Waste," Nat. Resour. J. 21, 703 (1981).
[4] C. D. Bowman et al., "Nuclear Energy Generation and Waste Transmutation Using an Accelerator-Driven Intense Thermal Neutron Source," Nucl. Instrum. Meth. A 320, 336 (1992).
[5] P. Slovic et al., "Perceived Risk, Stigma, and Potential Economic Impacts of a High-Level Nuclear Waste Repository in Nevada," Risk Anal. 11, 683 (1991).
[6] R. C. Ewing, W. J. Weber, and F. W. Clinard Jr., "Radiation Effects in Nuclear Waste Forms for High-Level Radioactive Waste," Prog. Nucl. Energy 29, 63 (1995).
