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| Fig. 1: A transport tank for nuclear waste on the Nevada roads. (Source: Wikimedia Commons). |
Nuclear waste is waste that contains any spent radioactive material from a nuclear process. Nuclear waste is a byproduct of various nuclear processes occurring in the medical, research, or nuclear power generation industries. Management of nuclear waste and practices in order to mitigate the possible dangers of nuclear waste are a continually evolving process.
Most of the radioactive waste produced comes from spent nuclear fuel cycles and nuclear electricity production and military activities. [1] It is also generated from research activities in universities in the study of biology, engineering, and chemistry and in hospitals from sterilizing medical devices and products as well as in the treatment and diagnosing of patients. [1] It is also produced in agriculture in the fabrication of genetically modified organisms (GMO's) that are more disease and drought resistant as well as crops that have shorter growth and yield times. [1]
In regards to spent nuclear fuel the radioactive waste comes both the front end of the nuclear fuel cycle and the back end, this is where the major hazard occurs. The front end involves the mining through the use of uranium use in the reactor. [1] Waste from this end of the cycle usually emits alpha radiation and contains radium and its decay products. [1] On the other side is the back end of the cycle that involves byproduct removal from the reactor to the disposal and subsequent treatment of the used fuel. [1] On the back end, most of the spent fuel rods contain fission products which emit alpha, beta, and gamma radiation.
One major concern that comes from spent nuclear waste is the proliferation of nuclear weapons since uranium and plutonium are possible materials for weapons. [2] A solution that has been suggested is to recycle the plutonium and use it as a fuel in fast reactors. [2]
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| Fig. 2: An aerial view of Yucca Mountain, NV. (Courtesy of the USGS. Source: Wikimedia Commons) |
In the United States there are certain regulated types of nuclear waster. These include Low-level waste (LLW), waste incidental to reprocessing (WIR), High-level waste (HLW), and Uranium mill tailings. [3] LLW includes radioactively contaminated rags, clothing, medical tubes, filters, tools, and many other items. [3] WIR refers to the various waste byproducts that come from the reprocessing of nuclear spent fuel. High level waste (HLW) is an irradiated or spent nuclear reactor fuel. [3] Uranium mill tailings are the residues remaining after the mining of natural ore from to extract thorium and uranium. [3]
Low-level waste disposal happens at commercially operated low level waste disposal sites licensed by the US National Regulatory Commission (NRC). [3] These facilities must be able to perform for thousands of years in the future due to the long half-lives of nuclear isotopes. In the US there are three existing LLW disposing facilities. There is no current HLW disposal site in the US. Proposals and plans for a deep geologic depository of HLW in Yucca Mountain, Nevada were ultimately suspended and withdrawn after comprehensive reports and studies determined possible safety and risk concerns with the site. Current storage for spent nuclear fuel involves two acceptable storage methods: spent fuel pools and dry cask storage. [3] Currently most of the spent nuclear reactor fuel is stored in these specially designed pools at the various individual reactor sites. [3] If the capacity of the nuclear pools is reached spent fuel may also be stored in dry storage systems. [3] Fig. 1 displays a transport tank for spent fuel or nuclear waste. Fig. 2 displays the proposed Yucca Mountain site for a HLW facility.
Another important concern regarding spent nuclear waste is its transportation to the disposal sites. Due to the hazardous radiation and heat produced the spent fuels must be transported in specially shielded casks or containers that contain the radioactivity and dissipate the heat. [3] Since the start of the shipment of nuclear waste there has never been a single reported incident of any radiological releases to the environment of public due to commercial shipping of nuclear waste. [3] Most of the shipments are transported between various reactors owned by the same utility company in order to share storage, or they may be shipped to a research facility where tests are conducted on the spent fuel itself. [3] Increases to the number of commercial shipments of spent fuel are expected to increase in the near future due to the potential of a HLW repository being built. [3]
Since the advent of nuclear technology's use in the U.S. the management and practices of how nuclear waste is stored or disposed of has been at the forefront of many minds. With the possible increase of nuclear technology this discussion of nuclear waste management will continue to become louder and it is important that it is done correctly. Whether the main concerns be the potential for damage to the environment or the general public, or the possible security risks, nuclear waste management is a high level concern in the U.S. and will continue to impact the lives of the U.S.' general population for many years to come.
© David Llanos. 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. G. Cochran, N. Tsoulfanidis, and W. F. Miller, The Nuclear Fuel Cycle: Analysis and Management (American Nuclear Society, 1993).
[2] "Current Issues in Nuclear Energy: Radioactive Waste," International Nuclear Societies Council, August 2002.
[3] "Radioactive Waste: Production, Storage, Disposal," U.S. Nuclear Regulatory Commission, NUREG/BR-0216, May 2002
