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Radio Active Waste

Primer on Radioactive Waste*

radsign What is radiation? Radiation is energy in the form of high speed particles or electromagnetic waves. It can be ionizing or non-ionizing. Non-ionizing radiation lacks the energy to alter atoms (e.g., visible light and microwaves). Ionizing radiation has enough energy to change normal cellular functioning. Ionizing radiation may cause cells to die or transform into a cancerous cell. Ionizing radiation is categorized by its strength or energy level into three main categories:
  • Alpha particles, although the most densely ionizing, are the weakest form of ionizing radiation. They can travel a few inches through the air but can be stopped by something as thin as a sheet of paper. This means that cells can be protected or shielded from damage by alpha particles by clothing. Even your skin will protect you from damage from alpha particles. However, if alpha particles are inhaled or ingested or get into a cut on the skin, they can cause damage to cells. As alpha particles decay inside the body, the surrounding cells absorb the radiation.
  • Beta particles contain more energy than alpha particles. These particles are able to travel several feet through the air, but can be stopped with denser materials such as wood, glass or aluminum foil.
  • Gamma rays are high-energy electromagnetic energy waves and the most penetrating type of radiation. They travel at the speed of light through the air. Cells must be shielded from gamma rays with concrete, lead or steel.

Radsignred.gif (58695 bytes)What is a Half-Life? Radioactive elements are unstable and spontaneously decay, causing them to emit radiation. The speed at which radionuclides decay is measured in "half-lives." A half-life is the time it takes for one-half of the radioactive atoms to decay into another form. Sometimes the form that the atoms decay into are also radioactive elements. After several half-lives only a fraction of the original radionuclides exist. Depending on the type of radionuclide, half-lives range from a few seconds to hundreds of millions and even billions of years. The type of ionizing radiation (i.e., alpha, beta, gamma) is NOT related to an element's half-life. For example, some alpha emitters, such as Uranium-234, have half-lives of hundreds of thousands of years. The Uranium-238 Decay Chain illustrates this point.

What is Radioactive Waste? Radioactive or nuclear wastes are the wastes that result from nuclear weapons production, nuclear power generation and other uses of nuclear materials. These wastes are usually categorized by their level of radioactivity (i.e., High-Level Waste, Transuranic Wastes, and Low-Level Waste). These waste also can be categorized by source. Defense-related radioactive wastes are those resulting from the research and development of nuclear weapons. Civilian or commercial nuclear wastes are the result of nuclear energy production, radioactive materials used in medical treatments and research and in certain commercial goods.

  • High-Level Wastes are very radioactive (gamma emitters). They require heavy shielding and remote handling. High-level wastes include spent (or used) nuclear fuel from nuclear reactors and wastes resulting from reprocessing of spent nuclear fuel. Fuel assemblies in nuclear reactors must be replaced after several years, when they are no longer efficient in producing electricity. Spent nuclear fuel is more radioactive than new fuel. Most spent nuclear fuel in the United States is currently located at nuclear generating plants across the country in pools of water to protect workers from radiation. Spent fuel also can be stored in large concrete casks.

    Reprocessing of spent nuclear fuel, which is the chemical separation of plutonium and uranium from other elements, is no longer done in the United States with spent fuel from commercial nuclear reactors. Almost all high-level wastes from reprocessing come from the reprocessing of fuel from weapons production reactors to obtain materials to make nuclear weapons. This waste is primarily in liquid form and can be "vitrified" into a glass or other solid substance.

    High-level radioactive waste is stored at nuclear power plants and DOE facilities across the country. DOE's Office of Civilian Radioactive Waste Management is charged with identifying and developing a suitable site for deep geologic disposal of this waste. They are currently conducting research to determine the suitability of a site for such disposal at Yucca Mountain, Nevada. Check out DOE's Yucca Mountain web site and the State of Nevada's Nuclear Waste Project web site.
  • Transuranic (TRU) wastes include laboratory clothing, tools, plastics, rubber gloves, wood, metals, glassware and solidified waste contaminated with man-made radioactive materials including plutonium, americium and neptunium. Some of these wastes, known as "mixed" transuranic waste, also contain hazardous chemical constituents that are regulated under the Resource Conservation and Recovery Act.  (TRU waste that does not contain regulated amounts of hazardous chemicals are called "non-mixed" TRU wastes.)   TRU wastes were created in the research, development and fabrication of nuclear weapons. They include all wastes contaminated with radionuclides possessing atomic numbers greater than uranium (which is 92) and half-lives greater than 20 years and are in concentrations greater than 100 nanocuries per gram.

    TRU waste is usually classified as either "contact-handled" (CH) or "remote-handled" (RH). CH-TRU emits mostly alpha radiation and therefore does not require heavy lead shielding. The primary radiation hazard posed by this waste is through inhalation or ingestion. Inhalation of certain transuranic materials, such as plutonium, even in very small quantities, could deliver significant internal radiation doses. RH-TRU wastes are primarily gamma emitters; consequently they require heavy shielding and must be handled robotically. RH-TRU present a much more significant external radiation hazard than CH-TRU waste.

    Currently most TRU is stored in 55-gallon drums or other containers at DOE facilities across the country. TRU wastes generated prior to 1970 are in shallow burial at these sites. While there is no plan to move currently buried wastes, DOE plans to dispose of some transuranic waste in the Waste Isolation Pilot Plant (or WIPP) in southeastern New Mexico. However, by law WIPP will be able to accept only a portion of the TRU waste that currently exists and will be generated in the future.

    Find out more about about plutonium from the Institute for Energy and Environmental Research.
  • Low-Level Wastes are those radioactive wastes that are not high-level and not transuranic. Most low-level waste (classified by the NRC as A, B or C) has relatively low levels of radioactivity, relatively short half-lives and can be disposed of by shallow burial. Wastes that are "greater than class C" require deep geologic disposal in specially licensed facilities.

* References used to generate this page:

The Nuclear Waste Primer: Handbook for Citizens, Revised Edition, by the League of Women Voters, Published by Lyons & Burford, 1993.

"What is Radiation? How Do We Measure It?" Backgrounder #4, produced by the National Safety Council's Environmental Health Center, December 12, 1996.

Contact Information
WIPP Transportation Safety Program
Coordinator, Eletha J. Trujillo
New Mexico Radioactive Waste Consultation Task Force
1220 South St. Francis Drive
Santa Fe, NM 87505
P: (505) 476-3224
F: (505) 476-3322

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