Low-level waste

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NRC Graphic of a low-level waste facility. Low-Level Waste Facility Graphic.jpg
NRC Graphic of a low-level waste facility.

Low-level waste (LLW) or Low-level radioactive waste (LLRW) is nuclear waste that does not fit into the categorical definitions for intermediate-level waste (ILW), high-level waste (HLW), spent nuclear fuel (SNF), transuranic waste (TRU), or certain byproduct materials known as 11e(2) wastes, such as uranium mill tailings. In essence, it is a definition by exclusion, and LLW is that category of radioactive wastes that do not fit into the other categories. If LLW is mixed with hazardous wastes as classified by RCRA, then it has a special status as mixed low-level waste (MLLW) and must satisfy treatment, storage, and disposal regulations both as LLW and as hazardous waste. While the bulk of LLW is not highly radioactive, the definition of LLW does not include references to its activity, and some LLW may be quite radioactive, as in the case of radioactive sources used in industry and medicine.

Contents

LLW includes items that have become contaminated with radioactive material or have become radioactive through exposure to neutron radiation. This waste typically consists of contaminated protective shoe covers and clothing, wiping rags, mops, filters, reactor water treatment residues, equipments and tools, luminous dials, medical tubes, swabs, injection needles, syringes, and laboratory animal carcasses and tissues. The radioactivity can range from just above background levels found in nature to very highly radioactive in certain cases such as parts from inside the reactor vessel in a nuclear power plant.

The definition of low-level waste is set by the nuclear regulators of individual countries, though the International Atomic Energy Agency (IAEA) provides recommendations. [1] Some countries, such as France, specify categories for long-lived low- and intermediate-level waste. U.S. regulations do not define the category of intermediate-level waste.

Disposal

Low-level waste storage pit at the Nevada National Security Site. NTS - Low-level radioactive waste storage pit.jpg
Low-level waste storage pit at the Nevada National Security Site.

Depending on who "owns" the waste, its handling and disposal is regulated differently. All nuclear facilities, whether they are a utility or a disposal site, have to comply with Nuclear Regulatory Commission (NRC) regulations. The four low-level waste facilities in the U.S. are Barnwell, South Carolina; Richland, Washington; Clive, Utah; and as of June 2013, Andrews County, Texas. [2] [3] The Barnwell and the Clive locations are operated by EnergySolutions, the Richland location is operated by U.S. Ecology, and the Andrews County location is operated by Waste Control Specialists. Barnwell, Richland, and Andrews County accept Classes A through C of low-level waste, whereas Clive only accepts Class A LLW. The DOE has dozens of LLW sites under management. The largest of these exist at DOE Reservations around the country (e.g. the Hanford Reservation, Savannah River Site, Nevada Test Site, Los Alamos National Laboratory, Oak Ridge National Laboratory, Idaho National Laboratory, to name the most significant).

Classes of wastes are detailed in 10 C.F.R. § 61.55 Waste Classification, [4] enforced by the Nuclear Regulatory Commission, reproduced in the table below. These are not all the isotopes disposed of at these facilities, just the ones that are of most concern for the long-term monitoring of the sites. Waste is divided into three classes, A through C, where A is the least radioactive and C is the most radioactive. Class A LLW is able to be deposited near the surface, whereas Classes B and C LLW have to be buried progressively deeper.

In 10 C.F.R. § 20.2002, the NRC reserves the right to grant a free release of radioactive waste. The overall activity of such a disposal cannot exceed 1 mrem/yr and the NRC regards requests on a case-by-case basis. Low-level waste passing such strict regulations is then disposed of in a landfill with other garbage. Items allowed to be disposed of in this way are: glow-in-the-dark watches (radium) and smoke detectors (americium) among other things.

RadionuclideClass A (Curies/m3)Class B (Ci/m3)Class C (Ci/m3) (upper limit for LLW)
Total of all nuclides with less than 5-year half life 700No limitNo limit
Tritium (3H)40No limitNo limit
Cobalt-60 (60Co)700No limitNo limit
Nickel-63 (63Ni)3.570700
Ni-63 in activated metal357007000
Strontium-90 (90Sr)0.041507000
Cesium-137 (137Cs)1444600
Carbon-14(14C)0.88
C-14 in activated metal880
Nickel-59 (59Ni) in activated metal22220
Niobium-94 (94Nb) in activated metal0.020.2
Technetium-99 (99Tc)0.33
Iodine-129 (129I)0.0080.08
Alpha emitting transuranic nuclides
with a half life greater than 5 years
10 nCi/g100 nCi/g
Plutonium-241 (241Pu)350 nCi/g3500 nCi/g
Curium-242 (242Cm)2000 nCi/g20000 nCi/g

LLW should not be confused with high-level waste (HLW) or spent nuclear fuel (SNF). C Class low level waste has a limit of 100 nano-Curies per gram of alpha-emitting transuranic nuclides with a half life greater than 5 years; any more than 100 nCi, and it must be classified as transuranic waste (TRU). These require different disposal pathways. TRU wastes from the U.S. nuclear weapons complex is currently disposed at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico, though other sites also are being considered for on-site disposal of particularly difficult to manage TRU wastes.

See also

Related Research Articles

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Hazardous waste

Hazardous waste is waste that has substantial or potential threats to public health or the environment.

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Radioactive contamination, also called radiological contamination, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids or gases, where their presence is unintended or undesirable.

Waste Isolation Pilot Plant deep geological repository for radioactive waste

The Waste Isolation Pilot Plant, or WIPP, is the world's third deep geological repository licensed to store transuranic radioactive waste for 10,000 years. The waste is from the research and production of United States nuclear weapons only. The plant started operation in 1999, and the project is estimated to cost $19 billion in total.

High-level waste

High-level waste (HLW) is a type of nuclear waste created by the reprocessing of spent nuclear fuel. It exists in two main forms:

Deep geological repository Radioactive and hazardous waste long term storage

A deep geological repository is a way of storing hazardous or radioactive waste within a stable geologic environment. It entails a combination of waste form, waste package, engineered seals and geology that is suited to provide a high level of long-term isolation and containment without future maintenance. This will prevent any radioactive dangers. A number of mercury, cyanide and arsenic waste repositories are operating worldwide including Canada and Germany and a number of radioactive waste storages are under construction with the Onkalo in Finland being the most advanced.

EnergySolutions, headquartered in Salt Lake City, Utah, is one of the largest processors of low level waste (LLW) in America, making it also one of the world's largest nuclear waste processors. It was formed in 2007 when Envirocare acquired three other nuclear waste disposal companies: Scientech D&D, BNG America, and Duratek.

Spent nuclear fuel

Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor. It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and depending on its point along the nuclear fuel cycle, it may have considerably different isotopic constituents.

Nuclear flask

A nuclear flask is a shipping container that is used to transport active nuclear materials between nuclear power station and spent fuel reprocessing facilities.

Maxey Flats

The Maxey Flats low-level radioactive waste (LLRW) disposal site is a Superfund site in Kentucky which served as a disposal site for low-level nuclear waste from 1963 to 1977. Investigations by the Environmental Protection Agency, among others, determined that plutonium stored at the site had migrated beyond the site's trenches, and the site was closed in 1977.

Transuranic waste (TRU) is stated by U.S. regulations, and independent of state or origin, to be waste which has been contaminated with alpha emitting transuranic radionuclides possessing half-lives greater than 20 years and in concentrations greater than 100 nCi/g (3.7 MBq/kg).

Nuclear entombment is a method of nuclear decommissioning in which radioactive contaminants are encased in a structurally long-lived material, such as concrete. This prevents radioactive material and other contaminated substances from being exposed to human activity and the environment. Entombment is usually applied to nuclear reactors, but also some nuclear test sites. Nuclear entombment is the least used of three methods for decommissioning nuclear power plants, the others being dismantling and safe enclosure. The use of nuclear entombment is more practical for larger nuclear power plants that are in need of both long and short term burials, as well as for power plants which seek to terminate their facility licenses. Entombment is used on a case by case basis because of its major commitment with years of surveillance and complexity until the radioactivity is no longer a major concern, permitting decommissioning and ultimate unrestricted release of the property. Considerations such as financial backing and the availability of technical know-how are also major factors.

Hazardous waste in the United States

Under United States environmental policy, hazardous waste is a waste that has the potential to:

High-level radioactive waste management Management and disposal of highly radioactive materials

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Waste management law

Waste management laws govern the transport, treatment, storage, and disposal of all manner of waste, including municipal solid waste, hazardous waste, and nuclear waste, among many other types. Waste laws are generally designed to minimize or eliminate the uncontrolled dispersal of waste materials into the environment in a manner that may cause ecological or biological harm, and include laws designed to reduce the generation of waste and promote or mandate waste recycling. Regulatory efforts include identifying and categorizing waste types and mandating transport, treatment, storage, and disposal practices.

Waste Control Specialists LLC (WCS) is a treatment, storage, & disposal company dealing in radioactive, hazardous, and mixed wastes. Developed and controlled by Texas billionaire investor Harold Simmons until his death at the end of 2013, the company was founded in Dallas, Texas in 1989 as a landfill operator, and awarded a unique license for disposal of low level radioactive waste in 2009. Its main operations are in remote West Texas.

Radioactive waste is generated from the nuclear weapons program, commercial nuclear power, medical applications, and corporate and university-based research programs. Some of the materials LLW consists of are: "gloves and other protective clothing, glass and plastic laboratory supplies, machine parts and tools, and disposable medical items that have come in contact with radioactive materials". Waste is generally categorized as high level waste (HLW) and low-level waste (LLW). LLW contains materials such as irradiated tools, lab clothing, ion exchanger resins, animal carcasses, and trash from defense, commercial nuclear power, medical, and research activities. These materials usually have radioactivity that have short half lives—from ranges of multiple days to several hundred years. In 1990, 1.1 million cubic feet of LLW was produced. Currently, U.S. reactors generate about 40,000 cubic meters of low-level radioactive waste per year, including contaminated components and materials resulting from reactor decommissioning.

From 1946 through 1993, thirteen countries used ocean disposal or ocean dumping as a method to dispose of nuclear/radioactive waste. The waste materials included both liquids and solids housed in various containers, as well as reactor vessels, with and without spent or damaged nuclear fuel. Since 1993, ocean disposal has been banned by international treaties.

The U.S. Nuclear Waste Technical Review Board was established in the 1987 Nuclear Waste Policy Amendments Act (NWPAA) to "...evaluate the technical and scientific validity of activities [related to managing and disposing of spent nuclear fuel and high-level radioactive waste] undertaken by the Secretary [of Energy], including

  1. site characterization activities; and
  2. activities relating to the packaging or transportation of high-level radioactive waste or spent nuclear fuel."

The advanced reprocessing of spent nuclear fuel is a potential key to achieve a sustainable nuclear fuel cycle and to tackle the heavy burden of nuclear waste management. In particular, the development of such advanced reprocessing systems may save natural resources, reduce waste inventory and enhance the public acceptance of nuclear energy. This strategy relies on the recycling of major actinides and the transmutation of minor actinides. In order to fulfill this objective, selective extracting agents need to be designed and developed by investigating their complexation mechanism.

References

Notes

  1. "Classification of Radioactive Waste : a Safety Guide. Safety Series No. 111-G-1.1" (PDF). RADWASS Programme. Vienna: IAEA. 1994. Archived from the original (PDF) on 15 May 2005.
  2. "Disposal of Commercial Low-Level Radioactive Waste". Nuclear Energy Institute. April 2014. Retrieved 8 May 2015.
  3. "New Federal Waste Facility Opens with Ribbon Cutting Ceremony" (PDF). Waste Control Specialists. 6 June 2013. Archived from the original (PDF) on 23 May 2014. Retrieved 9 May 2015.
  4. official online version of 10 C.F.R. § 61.55 Waste Classification

General references