Audeen W. Fentiman
Joyce E. Meredith
Ronald J. Veley
In the United States radioactive waste is divided into two major categories, high-level radioactive waste and low-level radioactive waste. There are two other very narrowly defined special categories which will be discussed later. Low-level waste is generally defined as any radioactive waste that does not belong in any of the other categories. As a result, low-level waste is a very broad category containing many different types of waste and a wide range of concentrations of radioactive materials. Low-level waste is divided into four classes with specific regulations for the disposal of each class.
This fact sheet defines low-level radioactive waste, gives examples of low-level waste, discusses the classes of low-level waste, and provides some information on the volumes of low-level waste generated.
As mentioned above, low-level radioactive waste is defined as any radioactive waste that does not belong in one of the other three categories. Those three categories are (1) high-level waste (spent nuclear fuel or the highly radioactive waste produced if spent fuel is reprocessed), (2) uranium milling residues, and (3) waste with greater than specified quantities of elements heavier than uranium.
Spent nuclear fuel is used fuel from nuclear power plants. Spent fuel contains some reusable material that may be recovered. That recovery process is called reprocessing, and everything left over after the reusable material has been recovered is classified as high-level radioactive waste. The United States is not presently reprocessing spent nuclear fuel.
Uranium milling residues are the rock and soil that remain after uranium has been removed from the ore that was mined from the earth. These milling residues are also known as mill tailings.
Radioactive waste that contains more than a specified concentration of elements heavier than uranium, known as transuranics, is not classified as low-level radioactive waste.
All other radioactive waste is low-level radioactive waste.
Low-level radioactive waste is generated at commercial facilities such as nuclear power plants, hospitals, and research institutions. It includes radioactive materials used in various processes as well as supplies and equipment that have been contaminated with radioactive materials. Low-level waste can include:
These items are just a few of the materials categorized as low-level radioactive waste.
Low-level radioactive waste is generated by both "commercial" operations and U.S. Department of Energy operations. The federal government is responsible for disposal of low-level waste generated by the Department of Energy including wastes from the atomic weapons program and from the decommissioning of nuclear reactors which power naval vessels. The states are responsible only for disposal of low-level waste from (1) commercial operations such as utilities, industries, hospitals, and research institutions, and (2) government facilities such as veterans' hospitals and non-weapons related government facilities.
The concentration of radioactive material in low-level radioactive waste can vary. Precautions that must be taken when handling low-level waste depend on the radionuclides present and their concentrations. Because of this, low-level waste is divided into four classes with specific regulations for each class.
Three classes of commercial low-level radioactive waste are defined in the Code of Federal Regulations, Title 10, Part 61 (10 CFR 61) . Those classes are Class A, Class B, and Class C. Section 10 CFR 61.55 lists the limits on concentrations of specific radioactive materials allowed in each low-level waste class. Radioactive waste not meeting the criteria for these classes falls into a fourth class, known as Greater Than Class C.
Class A low-level radioactive waste contains the lowest concentration of radioactive materials, and most of those materials have half-lives of less than five years. Class B contains the next lowest concentration of radioactive materials, and it contains a higher proportion of materials with longer half-lives. Class C low-level waste has the highest concentration of radioactive material allowed to be buried in a low-level waste disposal facility. The concentration of radioactive materials in Greater Than Class C exceeds the limits for Class C waste specified in 10 CFR 61.55. All Greater Than Class C waste is the responsibility of the federal government and must be disposed of in a geologic repository such as the high-level waste repository planned for Nevada.
The amount of low-level radioactive waste produced is usually described in one of two ways. One way is to give the volume of the waste (in cubic feet or cubic meters). The other way is to give the activity. Activity is a measure of the rate at which radiation is given off by the material in the waste and is measured in curies. The volumes and activities of commercial low-level waste disposed of in 1987 through 1991 are illustrated by Figure 1 and listed in Table 1. Data are presented for Ohio, the Midwest Compact, and the United States.
Figure 1. Volume and Activity of Commercial Low-Level Radioactive Waste for 1987 through 1991
| Table 1. Volume and Activity of Commercial Low-Level Radioactive Waste for 1987 through 1991 | |||
|---|---|---|---|
| Ohio | Midwest Compact | United States | |
| Volume (in cubic feet) | |||
| 1987 | 18662 | 125930 | 1844504 |
| 1988 | 22585 | 96808 | 1429016 |
| 1989 | 58866 | 157821 | 1627813 |
| 1990 | 24147 | 123349 | 1142810 |
| 1991 | 24336 | 112679 | 1369303 |
| Activity (in Curies) | |||
| 1987 | 309 | 9443 | 269550 |
| 1988 | 837 | 9474 | 259658 |
| 1989 | 1211 | 88234 | 866898 |
| 1990 | 4316 | 66212 | 547902 |
| 1991 | 3840 | 12828 | 799811 |
The majority of commercial low-level radioactive waste, by volume, is Class A; this large volume contains a small fraction of the activity. Class C waste, on the other hand, is less than one percent of the volume but contains more than half of the activity. The percentages of volume and activity of low-level waste by class (A, B, C) are presented in Table 2. These data are for all commercial low-level waste shipped for disposal in the United States in 1987, the last year for which data are available on the activity by class.
| Table 2. Volume and Activity of Low-Level Radioactive Waste by Class for 1987 | ||
|---|---|---|
| Volume % | Activity % | |
| Class A | 97.4 | 9.7 |
| Class B | 2.1 | 24.8 |
| Class C | 0.5 | 65.5 |
It is important to note that the volume and activity of low-level radioactive waste generated and shipped in the United States each year can vary significantly, depending upon the operations conducted by the waste generators during that year.
If you would like to read more about low-level radioactive waste, some of the references listed below and other fact sheets in this series may be helpful.
1991 State-by-State Assessment of Low-Level Radioactive Wastes Received at Commercial Disposal Sites, DOE/LLW-152, National Low-Level Radioactive Waste Management Program, EG&G Idaho, Inc., Idaho Falls, 1992. (Similar volumes are available for 1986-1990.)
Code of Federal Regulations, Title 10, Part 61, "Licensing Requirements for Land Disposal of Radioactive Waste", 1992.
Edward L. Gershey et.al., Low-Level Radioactive Waste From Cradle to Grave, Van Nostrand Reinhold, New York, 1990.
Isabelle P. Weber and Susan D. Wiltshire, The Nuclear Waste Primer: A Handbook for Citizens, The League of Women Voters Education Fund, Nick Lyons Books, New York, 1985.
Michael E. Burns, ed., Low-Level Radioactive Waste Regulation: Science, Politics and Fear, Lewis Publishers, Inc., Chelsea, Michigan, 1988.
Public Law 99-240, "Low-Level Radioactive Waste Policy Amendments Act", 1985.
Dr. Audeen W. Fentiman is an Assistant Professor in Nuclear Engineering at The Ohio State University. Joyce E. Meredith and Ronald J. Veley are Graduate Research Associates, Ohio State University Extension.
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Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.
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