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PART 20—STANDARDS FOR PROTECTION AGAINST RADIATION
Subpart K--Waste Disposal
§ 20.2001 General requirements.
(a) A licensee shall dispose of licensed material only--
(1) By transfer to an authorized recipient as provided in § 20.2006 or in the regulations in parts 30, 40, 60, 61, 63, 70, and 72 of this chapter;
(2) By decay in storage; or
(3) By release in effluents within the limits in § 20.1301; or
(4) As authorized under §§ 20.2002, 20.2003, 20.2004, 20.2005, or 20.2008.
(b) A person must be specifically licensed to receive waste containing licensed material from other persons for:
(1) Treatment prior to disposal; or
(2) Treatment or disposal by incineration; or
(3) Decay in storage; or
(4) Disposal at a land disposal facility licensed under part 61 of this chapter; or
(5) Disposal at a geologic repository under part 60 or part 63 of this chapter.
§ 20.2002 Method for obtaining approval of proposed disposal procedures.
A licensee or applicant for a license may apply to the Commission for approval of proposed procedures, not otherwise authorized in the regulations in this chapter, to dispose of licensed material generated in the licensee's activities. Each application shall include:
(a) A description of the waste containing licensed material to be disposed of, including the physical and chemical properties important to risk evaluation, and the proposed manner and conditions of waste disposal; and
(b) An analysis and evaluation of pertinent information on the nature of the environment; and
(c) The nature and location of other potentially affected licensed and unlicensed facilities; and
(d) Analyses and procedures to ensure that doses are maintained ALARA and within the dose limits in this part.
§ 20.2003 Disposal by release into sanitary sewerage.
(a) A licensee may discharge licensed material into sanitary sewerage if each of the following conditions is satisfied:
(1) The material is readily soluble (or is readily dispersible biological material) in water; and
(2) The quantity of licensed or other radioactive material that the licensee releases into the sewer in 1 month divided by the average monthly volume of water released into the sewer by the licensee does not exceed the concentration listed in table 3 of appendix B to part 20; and
(3) If more than one radionuclide is released, the following conditions must also be satisfied:
(i) The licensee shall determine the fraction of the limit in table 3 of appendix B to part 20 represented by discharges into sanitary sewerage by dividing the actual monthly average concentration of each radionuclide released by the licensee into the sewer by the concentration of that radionuclide listed in table 3 of appendix B to part 20; and
(ii) The sum of the fractions for each radionuclide required by paragraph (a)(3)(i) of this section does not exceed unity; and
(4) The total quantity of licensed and other radioactive material that the licensee releases into the sanitary sewerage system in a year does not exceed 5 curies (185 GBq) of hydrogen-3, 1 curie (37 GBq) of carbon-14, and 1 curie (37 GBq) of all other radioactive materials combined.
(b) Excreta from individuals undergoing medical diagnosis or therapy with radioactive material are not subject to the limitations contained in paragraph (a) of this section.
§ 20.2004 Treatment or disposal by incineration.
(a) A licensee may treat or dispose of licensed material by incineration only:
(1) As authorized by paragraph (b) of this section; or
(2) If the material is in a form and concentration specified in § 20.2005; or
(3) As specifically approved by the Commission pursuant to § 20.2002.
(b) (1) Waste oils (petroleum derived or synthetic oils used principally as lubricants, coolants, hydraulic or insulating fluids, or metalworking oils) that have been radioactively contaminated in the course of the operation or maintenance of a nuclear power reactor licensed under part 50 of this chapter may be incinerated on the site where generated provided that the total radioactive effluents from the facility, including the effluents from such incineration, conform to the requirements of appendix I to part 50 of this chapter and the effluent release limits contained in applicable license conditions other than effluent limits specifically related to incineration of waste oil. The licensee shall report any changes or additions to the information supplied under §§ 50.34 and 50.34a of this chapter associated with this incineration pursuant to § 50.71 of this chapter, as appropriate. The licensee shall also follow the procedures of § 50.59 of this chapter with respect to such changes to the facility or procedures.
(2) Solid residues produced in the process of incinerating waste oils must be disposed of as provided by § 20.2001.
(3) The provisions of this section authorize onsite waste oil incineration under the terms of this section and supersede any provision in an individual plant license or technical specification that may be inconsistent.
§ 20.2005 Disposal of specific wastes.
(a) A licensee may dispose of the following licensed material as if it were not radioactive:
(1) 0.05 microcurie (1.85 kBq), or less, of hydrogen-3 or carbon-14 per gram of medium used for liquid scintillation counting; and
(2) 0.05 microcurie (1.85 kBq), or less, of hydrogen-3 or carbon-14 per gram of animal tissue, averaged over the weight of the entire animal.
(b) A licensee may not dispose of tissue under paragraph (a)(2) of this section in a manner that would permit its use either as food for humans or as animal feed.
(c) The licensee shall maintain records in accordance with § 20.2108.
§ 20.2006 Transfer for disposal and manifests.
(a) The requirements of this section and appendix G to 10 CFR Part 20 are designed to--
(1) Control transfers of low-level radioactive waste by any waste generator, waste collector, or waste processor licensee, as defined in this part, who ships low-level waste either directly, or indirectly through a waste collector or waste processor, to a licensed low-level waste land disposal facility (as defined in Part 61 of this chapter);
(2) Establish a manifest tracking system; and
(3) Supplement existing requirements concerning transfers and recordkeeping for those wastes.
(b) Any licensee shipping radioactive waste intended for ultimate disposal at a licensed land disposal facility must document the information required on NRC's Uniform Low-Level Radioactive Waste Manifest and transfer this recorded manifest information to the intended consignee in accordance with appendix G to 10 CFR Part 20.
(c) Each shipment manifest must include a certification by the waste generator as specified in section II of appendix G to 10 CFR Part 20.
(d) Each person involved in the transfer for disposal and disposal of waste, including the waste generator, waste collector, waste processor, and disposal facility operator, shall comply with the requirements specified in section III of appendix G to 10 CFR Part 20.
(e) Any licensee shipping byproduct material as defined in paragraphs (3) and (4) of the definition of Byproduct material set forth in § 20.1003 intended for ultimate disposal at a land disposal facility licensed under part 61 of this chapter must document the information required on the NRC’s Uniform Low-Level Radioactive Waste Manifest and transfer this recorded manifest information to the intended consignee in accordance with appendix G to this part.
§ 20.2007 Compliance with environmental and health protection regulations.
Nothing in this subpart relieves the licensee from complying with other applicable Federal, State, and local regulations governing any other toxic or hazardous properties of materials that may be disposed of under this subpart.
§ 20.2008 Disposal of certain byproduct material.
(a) Licensed material as defined in paragraphs (3) and (4) of the definition of Byproduct material set forth in §20.1003 may be disposed of in accordance with part 61 of this chapter, even though it is not defined as low-level radioactive waste. Therefore, any licensed byproduct material being disposed of at a facility, or transferred for ultimate disposal at a facility licensed under part 61 of this chapter, must meet the requirements of § 20.2006.
(b) A licensee may dispose of byproduct material, as defined in paragraphs (3) and (4) of the definition of Byproduct material set forth in § 20.1003, at a disposal facility authorized to dispose of such material in accordance with any Federal or State solid or hazardous waste law, including the Solid Waste Disposal Act, as authorized under the Energy Policy Act of 2005.
§ 20.2108 Records of waste disposal.
(a) Each licensee shall maintain records of the disposal of licensed materials made under §§ 20.2002, 20.2003, 20.2004, 20.2005, 10 CFR part 61 and disposal by burial in soil, including burials authorized before January 28, 1981. 6
(b) The licensee shall retain the records required by paragraph (a) of this section until the Commission terminates each pertinent license requiring the record. Requirements for disposition of these records, prior to license termination, are located in §§ 30.51, 40.61, 70.51, and 72.80 for activities licensed under these parts.
Subpart C—General Technical Requirements
§ 35.92 Decay-in-storage.
(a) A licensee may hold byproduct material with a physical half-life of less than or equal to 120 days for decay-in-storage before disposal without regard to its radioactivity if it—
(1) Monitors byproduct material at the surface before disposal and determines that its radioactivity cannot be distinguished from the background radiation level with an appropriate radiation detection survey meter set on its most sensitive scale and with no interposed shielding; and
(2) Removes or obliterates all radiation labels, except for radiation labels on materials that are within containers and that will be managed as biomedical waste after they have been released from the licensee.
(b) A licensee shall retain a record of each disposal permitted under paragraph (a) of this section in accordance with § 35.2092.
Subpart L—Records
§ 35.2092 Records of decay-in-storage.
A licensee shall maintain records of the disposal of licensed materials, as required by § 35.92, for 3 years. The record must include the date of the disposal, the survey instrument used, the background radiation level, the radiation level measured at the surface of each waste container, and the name of the individual who performed the survey.
PART 61—LICENSING REQUIREMENTS FOR LAND DISPOSAL OF RADIOACTIVE WASTE
Subpart A--General Provisions
§ 61.1 Purpose and scope.
(a) The regulations in this part establish, for land disposal of radioactive waste, the procedures, criteria, and terms and conditions upon which the Commission issues licenses for the disposal of radioactive wastes containing byproduct, source and special nuclear material received from other persons. Disposal of waste by an individual licensee is set forth in part 20 of this chapter. Applicability of the requirements in this part to Commission licenses for waste disposal facilities in effect on the effective date of this rule will be determined on a case-by-case basis and implemented through terms and conditions of the license or by orders issued by the Commission.
(b) Except as provided in part 150 of this chapter, which addresses assumption of certain regulatory authority by Agreement States, and § 61.6 "Exemptions," the regulations in this part apply to all persons in the United States. The regulations in this part do not apply to--
(1) Disposal of high-level waste as provided for in part 60 or 63 of this chapter;
(2) Disposal of uranium or thorium tailings or wastes (byproduct material as defined in § 40.4 (a-1) as provided for in part 40 of this chapter in quantities greater than 10,000 kilograms and containing more than 5 millicuries of radium-226; or
(3) Disposal of licensed material as provided for in part 20 of this chapter.
(c) This part also gives notice to all persons who knowingly provide to any licensee, applicant, contractor, or subcontractor, components, equipment, materials, or other goods or services, that relate to a licensee's or applicant's activities subject to this part, that they may be individually subject to NRC enforcement action for violation of § 61.9b
Backgrounder on Radioactive Waste
· Responsibilities of Other Government Agencies
Background
Radioactive (or nuclear) waste is a byproduct from nuclear reactors, fuel processing plants, hospitals and research facilities. Radioactive waste is also generated while decommissioning and dismantling nuclear reactors and other nuclear facilities. There are two broad classifications: high-level or low-level waste. High-level waste is primarily spent fuel removed from reactors after producing electricity. Low-level waste comes from reactor operations and from medical, academic, industrial, and other commercial uses of radioactive materials.
The NRC regulates the storage and disposal of all commercially generated radioactive wastes in the United States. The NRC also regulates high-level wastes generated by the Department of Energy that are subject to long-term storage and not used for, or part of, research and development activities. Regulations establish minimum acceptable performance criteria for licensees managing wastes, while providing for flexibility in technological approach.
High-Level Waste
High-level radioactive waste primarily is uranium fuel that has been used in a nuclear power reactor and is "spent," or no longer efficient in producing electricity. Spent fuel is thermally hot as well as highly radioactive and requires remote handling and shielding. Nuclear reactor fuel contains ceramic pellets of uranium 235 inside of metal rods. Before these fuel rods are used, they are only slightly radioactive and may be handled without special shielding.
During the fission process, two things happen to the uranium in the fuel. First, uranium atoms split, creating energy that is used to produce electricity. The fission creates radioactive isotopes of lighter elements such as cesium-137 and strontium-90. These isotopes, called "fission products," account for most of the heat and penetrating radiation in high-level waste. Second, some uranium atoms capture neutrons produced during fission. These atoms form heavier elements such as plutonium. These heavier-than-uranium, or "transuranic," elements do not produce nearly the amount of heat or penetrating radiation that fission products do, but they take much longer to decay. Transuranic wastes, sometimes called TRU, account for most of the radioactive hazard remaining in high-level waste after 1,000 years.
Radioactive isotopes eventually decay, or disintegrate, to harmless materials. Some isotopes decay in hours or even minutes, but others decay very slowly. Strontium-90 and cesium-137 have half-lives of about 30 years (half the radioactivity will decay in 30 years). Plutonium-239 has a half-life of 24,000 years.
High-level wastes are hazardous because they produce fatal radiation doses during short periods of direct exposure. For example, 10 years after removal from a reactor, the surface dose rate for a typical spent fuel assembly exceeds 10,000 rem/hour – far greater than the fatal whole-body dose for humans of about 500 rem received all at once. If isotopes from these high-level wastes get into groundwater or rivers, they may enter food chains. The dose produced through this indirect exposure would be much smaller than a direct-exposure dose, but a much larger population could be exposed.
Reprocessing separates residual uranium and plutonium from the fission products. The uranium and plutonium can be used again as fuel. Most of the high-level waste (other than spent fuel) generated over the last 35 years has come from reprocessing fuel from government-owned plutonium production reactors and from naval, research and test reactors. A small amount of liquid high-level waste was generated from reprocessing commercial power reactor fuel in the 1960s and early 1970s. There is no commercial reprocessing of nuclear power fuel in the United States at present; almost all existing commercial high-level waste is unreprocessed spent fuel.
Storage and Disposal
All U.S. nuclear power plants store spent nuclear fuel in "spent fuel pools." These pools are made of reinforced concrete several feet thick, with steel liners. The water is typically about 40 feet deep and serves both to shield the radiation and cool the rods.
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Dry Cask Storage of Spent Fuel |
As the pools near capacity, utilities move some of the older spent fuel into "dry cask" storage. These casks are stainless steel canisters surrounded by concrete. Fuel is typically cooled at least five years in the pool before transfer to cask. NRC has authorized transfer as early as three years; the industry norm is about 10 years. The NRC certifies cask designs and licenses dry cask storage facilities for up to 40 years. The certifications and licenses can be renewed.
The NRC believes spent fuel pools and dry casks both provide adequate protection for public health and safety and the environment. Therefore there is no pressing safety or security reason to mandate earlier transfer of fuel from pool to cask.
Spent fuel storage at power plant sites is considered temporary, with the ultimate goal being permanent disposal. However, at this time there are no facilities for permanent disposal of high-level waste. In the Nuclear Waste Policy Act of 1982, amended in 1987, Congress directed the Department of Energy to design and construct an underground geologic repository at Yucca Mountain, Nevada. DOE applied to the NRC for a construction authorization in 2008; however, DOE canceled the project in 2010 before the NRC completed its review. The NRC closed out its review and the associated adjudicatory hearing in 2011. The NRC resumed its review in late 2013 to comply with an appeals court ruling. For more information on this process, see the backgrounder on Licensing Yucca Mountain.
NRC Responsibilities
The NRC licenses and regulates the receipt and possession of high-level waste at privately-owned facilities and at certain DOE facilities. The DOE facilities subject to NRC regulation are defined by law to include: (1) facilities used primarily for receiving and storing high-level waste from activities licensed under the Atomic Energy Act and (2) facilities other than Research and Development facilities authorized for the express purpose of long-term storage of DOE-generated waste. Facilities for permanent disposal will require a license from NRC under these provisions.
Currently, facilities at reactor sites and at Morris, Illinois, and the Idaho National Engineering and Environmental Laboratory are licensed by NRC for temporary storage of spent fuel.
By law, the Commission is not authorized to license:
· Receipt or possession of high-level waste used for or part of DOE activities in a DOE research and development facility;
· DOE facilities for the short-term storage of high-level waste from DOE activities (such as existing DOE high-level waste storage tanks);
· Operating DOE facilities for the storage or disposal of transuranic contaminated waste, foreign high-level waste not resulting from a licensed activity, and low-level wastes;
· Decommissioned DOE facilities, except those covered under Section 202 of the Energy Reorganization Act. (Section 202 authorizes NRC to license certain DOE facilities, including not only the high-level waste storage facilities noted above, but also certain demonstration reactors);
· DOE high-level waste processing facilities, such as those for solidification, strontium and cesium extraction, and waste crystallization.
Responsibilities of Other Government Agencies
Other government agencies play a role in managing high-level waste.
The Department of Energy plans and carries out programs for safe handling of DOE-generated radioactive wastes, develops waste disposal technologies, and will design, construct and operate disposal facilities for DOE-generated and commercial high-level wastes. DOE has completed solidifying the liquid wastes that are currently in storage at West Valley in New York State. The Nuclear Waste Policy Act of 1982 sets specific roles and schedules for the DOE to follow in developing high-level waste repositories. (The repositories will be licensed by the NRC.)
The Environmental Protection Agency develops environmental standards and federal radiation protection guidance for offsite radiation due to the disposal of spent nuclear fuel and high-level and transuranic radioactive wastes. The standards limit the amount of radioactivity entering the biosphere outside the boundaries of the facility and also limit the radiation exposure to the public from management of spent fuel and waste prior to disposal. The guidance establishes criteria for disposing of waste.
The Department of Transportation regulates both the packaging and carriage of all hazardous materials including radioactive waste. Packaging must meet NRC regulations, which are compatible with internationally developed standards, and the package design must be reviewed and certified by NRC. DOT sets limits for external radiation levels and contamination, and controls the mechanical condition of carrier equipment and qualifications of carrier personnel.
The Department of the Interior , through the U.S. Geological Survey, conducts laboratory and field geologic investigations in support of DOE's waste disposal programs and collaborates with DOE on the earth science technical activities. The Bureau of Land Management, within DOI, manages certain public lands. DOI may withdraw such public lands for the limited exclusive use of DOE in support of radioactive waste disposal actions.
LOW-LEVEL WASTE
Low-level wastes, generally defined as radioactive wastes other than high-level and wastes from uranium recovery operations, are commonly disposed of in near-surface facilities rather than in a geologic repository. There is no intent to recover the wastes once they are disposed of.
Low-level waste 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, equipment 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 much higher levels in certain cases such as parts from inside the reactor vessel in a nuclear power plant.
Low-level waste is typically stored on-site by licensees, either until it has decayed away and can be disposed of as ordinary trash, or until amounts are large enough for shipment to a low-level waste disposal site in approved containers.
The NRC's regulations (10 CFR Part 61) establish procedures, criteria, terms and conditions for licensing low-level waste disposal sites. Part 61 also provides the basis for Agreement State regulations, since state rules must be compatible with NRC requirements. Additionally, licensees may use 10 CFR 20.2002 to dispose of low-level wastes that typically are a small fraction of the Class A limits in Part 61. The extensive controls in Part 61 are not needed to ensure protection of public health and safety and the environment from such wastes.
There have been eight operating commercial facilities in the United States licensed to dispose of low-level radioactive wastes. They are located at (1) West Valley, New York; (2) Maxey Flats near Morehead, Kentucky; (3) Sheffield, Illinois; (4) Beatty, Nevada; (5) Hanford, Washington; (6) Clive, Utah; (7) Barnwell, South Carolina; and (8) Andrews, Texas. At the present time, only the latter four sites are receiving waste for disposal; they are regulated by the states. Burial of transuranic waste is limited at all of the sites. Transuranic waste includes material contaminated with radioactive elements (e.g., neptunium, americium, plutonium) that are artificially made and is produced primarily from reprocessing spent fuel and from use of plutonium in fabrication of nuclear weapons.
Mill Tailings
Another type of radioactive waste consists of tailings generated during the milling of certain ores to extract uranium or thorium. These wastes have relatively low concentrations of radioactive materials with long half-lives. Tailings contain radium (which, through radioactive decay, becomes radon), thorium, and small residual amounts of uranium left over from during the milling process. Part 40 Appendix A of the NRC's regulations sets procedures and criteria for disposing of mill tailings and maintaining the disposal site.
Nuclear Materials
· Special Nuclear Material consists of plutonium, uranium-233 or uranium with U233 or U235 content greater than that found in nature (i.e., >0.71% U235)
· Source Material is thorium or uranium with a U235 content equal to or less than that found in nature (i.e., ≤ 0.71% U235)
· Byproduct Material , in general, is radioactive material other than source or special nuclear material. Specifically, by-product material is (a) isotopes produced or created in a nuclear reactor; (b) the tailings and waste produced by extracting or concentrating uranium or thorium from an ore processed primarily for its source material content; (c) discrete sources of radium-226 and (d) discrete sources of naturally occurring or accelerator-produced isotopes that pose a threat equal to or greater than a discrete source of radium-226.
· Radium is a radioactive substance found in nature. Radium is produced by the radioactive decay of uranium. The intensity of radiation from radioactive materials decreases over time. The time required for the intensity to decrease by one-half is referred to as the half-life. The half-life of radium is approximately 1,600 years.
Types of radioactive waste
http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-wastes/radioactive-waste-management.aspx
Radioactive waste includes any material that is either intrinsically radioactive, or has been contaminated by radioactivity, and that is deemed to have no further use. Government policy dictates whether certain materials – such as used nuclear fuel and plutonium – are categorised as waste.
Every radionuclide has a half-life – the time taken for half of its atoms to decay, and thus for it to lose half of its radioactivity. Radionuclides with long half-lives tend to be alpha and beta emitters – making their handling easier – while those with short half-lives tend to emit the more penetrating gamma rays. Eventually all radioactive waste decays into non-radioactive elements. The more radioactive an isotope is, the faster it decays. Radioactive waste is typically classified as either low-level (LLW), intermediate-level (ILW), or high-level (HLW), dependent, primarily, on its level of radioactivity.
Low-level waste
Low-level waste (LLW) has a radioactive content not exceeding four giga-becquerels per tonne (GBq/t) of alpha activity or 12 GBq/t beta-gamma activity. LLW does not require shielding during handling and transport, and is suitable for disposal in near surface facilities.
LLW is generated from hospitals and industry, as well as the nuclear fuel cycle. It comprises paper, rags, tools, clothing, filters, etc., which contain small amounts of mostly short-lived radioactivity. To reduce its volume, LLW is often compacted or incinerated before disposal. LLW comprises some 90% of the volume but only 1% of the radioactivity of all radioactive waste.
Intermediate-level waste
Intermediate-level waste (ILW) is more radioactive than LLW, but the heat it generates (<2 kW/m3) is not sufficient to be taken into account in the design or selection of storage and disposal facilities. Due to its higher levels of radioactivity, ILW requires some shielding.
ILW typically comprises resins, chemical sludges, and metal fuel cladding, as well as contaminated materials from reactor decommissioning. Smaller items and any non-solids may be solidified in concrete or bitumen for disposal. It makes up some 7% of the volume and has 4% of the radioactivity of all radioactive waste.
High-level waste
High-level waste (HLW) is sufficiently radioactive for its decay heat (>2kW/m3) to increase its temperature, and the temperature of its surroundings, significantly. As a result, HLW requires cooling and shielding.
HLW arises from the 'burning' of uranium fuel in a nuclear reactor. HLW contains the fission products and transuranic elements generated in the reactor core. HLW accounts for just 3% of the volume, but 95% of the total radioactivity of produced waste. There are two distinct kinds of HLW:
•Used fuel that has been designated as waste.
•Separated waste from reprocessing of used fuel.
HLW has both long-lived and short-lived components, depending on the length of time it will take for the radioactivity of particular radionuclides to decrease to levels that are considered non-hazardous for people and the surrounding environment. If generally short-lived fission products can be separated from long-lived actinides, this distinction becomes important in management and disposal of HLW.
HLW is the focus of significant attention regarding nuclear power, and is managed accordingly.
Very low-level waste
Exempt waste and very low-level waste (VLLW) contains radioactive materials at a level which is not considered harmful to people or the surrounding environment. It consists mainly of demolished material (such as concrete, plaster, bricks, metal, valves, piping, etc.) produced during rehabilitation or dismantling operations on nuclear industrial sites. Other industries, such as food processing, chemical, steel, etc., also produce VLLW as a result of the concentration of natural radioactivity present in certain minerals used in their manufacturing processes (see also information page on Naturally-Occurring Radioactive Materials). The waste is therefore disposed of with domestic refuse, although countries such as France are currently developing specifically designed VLLW disposal facilities.
What is low-level radioactive waste?
Low-level radioactive waste streams contain source , special nuclear , or byproduct material that are acceptable for disposal in a near-surface (i.e., within the upper 30 meters of the earth's surface) land disposal facility. For the purposes of this definition, low-level waste has the same meaning as in the Low-Level Radioactive Waste Policy Act , that is, radioactive waste not classified as high-level radioactive waste , transuranic waste , spent nuclear fuel , or byproduct material as defined in section 11e.(2) of the Atomic Energy Act (i.e., uranium or thorium tailings and waste).
Industries; hospitals and medical, educational, or research institutions; private or government laboratories; and nuclear fuel cycle facilities (e.g., nuclear power reactors and fuel fabrication plants) that use radioactive materials generate low-level wastes as part of their normal operations. These waste streams are generated in many physical and chemical forms and levels of contamination.
Which regulations apply to land disposal of low-level radioactive waste?
Regulations issued by the U.S. Nuclear Regulatory Commission (NRC) are found in Chapter I of Title 10, "Energy," of the Code of Federal Regulations ( 10 CFR ). Chapter I is divided into Parts 1 through 199, which contain requirements that are binding for all individuals and entities that possess, use, or store nuclear materials or operate nuclear facilities under the NRC's jurisdiction. Of these, the regulations that are most relevant to land disposal of radioactive waste are contained in 10 CFR Part 61 , "Licensing Requirements for Land Disposal of Radioactive Waste."
4.4.1.3 Mixed Waste (LLRMW)
Mixed wastes are defined by the Low Level Radioactive Waste Policy Act (NRC), Public Law 96-573, and it’s implementing regulations, as containing radioactive material not classified as high-level radioactive waste, transuranic waste, spent nuclear fuel, or by-product material as defined by Section 11e.(2) of the AEA (NRC) as well as hazardous waste under RCRA, 40 CFR 239-282 (EPA) (and the State equivalent thereof).
Low-level radioactive mixed waste (LLRMW), which contains both radioactive and hazardous wastes, is now banned from shallow land burial by federal and state regulations. At present, it can only be disposed of in a specially designed facility as outlined in a joint U.S. Nuclear Regulatory Commission and Environmental Protection Agency guidance document. This facility consists of a double-linear leachate collection system (DLLS) with a 30-yr design life. The guidance document also allows alternate design proposals by a licensed applicant for their site-specific needs. Taking advantage of this clause, Westinghouse Hanford Company has designed and fabricated a Hanford alternate liner leachate (HALL) system for the disposal of LLRMW. This design meets and exceeds all the requirements stipulated in the state and federal regulations and has many advantages over the DLLS. https://www.osti.gov/scitech/biblio/6927290-disposal-low-level-mixed-waste
EPA: Low-Activity Radioactive Wastes
"Low-Activity" Radioactive Wastes (LARW) are informally defined as radioactive wastes that contain very small concentrations of radionuclides Help. The concentrations are small enough that protection of public health and the environment from these wastes may not require all of the radiation protection measures necessary to manage higher-activity radioactive material. At this time, “low-activity” itself is a concept, not a definition. Among the wastes that could be addressed as “low-activity” are mixed wastesHelp (chemically hazardous and radioactive), wastes containing natural radioactivityHelp, cleanup wastes and other low-level radioactive wastes. Present regulation of “low-activity” radioactive waste is inconsistent, often based on the origin of the waste. Besides inconsistent regulation, cost and availability of disposal affect the way low-activity wastes are managed.
What are unique waste streams?
Depleted uranium is unique because the relatively high concentration and large quantity generated by uranium enrichment facilities were not considered by the U.S. Nuclear Regulatory Commission (NRC) in the Final Environmental Impact Statement ( NUREG-0945 ) supporting regulations in 10 CFR Part 61 , "Licensing Requirements for Land Disposal of Radioactive Waste." The NRC recognizes that the analysis supporting the criteria did not address the disposal of significant quantities of depleted uranium, and that there may be a need to place additional restrictions at a specific site or deny such disposal based on unique site characteristics.
Therefore, the NRC will update the regulations in 10 CFR Part 61 to specify a requirement for a site-specific analysis that demonstrates unique waste streams, including significant quantities of depleted uranium, can be disposed of safely. As currently envisioned, unique waste streams could include those that emerge in the future from new facilities that generate significantly different concentrations or quantities of waste not previously considered in NUREG-0945. As part of the rulemaking process for 10 CFR Part 61 , NRC will be soliciting public comment on defining unique waste streams.
What are some of the key issues with disposal of unique waste streams?
The U.S. Nuclear Regulatory Commission (NRC) staff has identified several key issues for initial discussion with stakeholders. These include defining key regulatory terms such as unique waste streams and significant quantities of depleted uranium as well as technical parameters of a site-specific analysis including a time period of performance, appropriate exposure scenarios for protection of the public and individuals from inadvertent intrusion. The NRC staff is also soliciting stakeholder views on technical issues for a site-specific analysis of near-surface disposal of significant quantities of depleted uranium. These technical issues include appropriate considerations for depleted uranium waste form(s), uranium geochemistry, and radon migration and exposure. These issues arose from the results of the NRC staff's technical analysis ( SECY-08-0147 ) that was submitted to the Commission on October 7, 2008, in response to Commission Order CLI-05-20 regarding depleted uranium. Given those issues, the Commission's related Staff Requirements Memorandum ( SRM-SECY-08-0147 ), dated March 18, 2009, instructed the staff to begin engagement with stakeholders and interested parties to initiate development of the technical basis for possible revision of the 10 CFR Part 61 , "Licensing Requirements for Land Disposal of Radioactive Waste." Toward that end, the staff has scheduled public workshops to discuss the benefits and impacts of revising 10 CFR Part 61 . In so doing, the staff hopes to identify potential conflicts and gain an understanding of any unintended consequences that may result from drafting and implementing related changes to the NRC's existing regulations
Agreement State Program
NRC provides assistance to States expressing interest in establishing programs to assume NRC regulatory authority under the Atomic Energy Act of 1954, as amended. Section 274 of the Act provides a statutory basis under which NRC relinquishes to the States portions of its regulatory authority to license and regulate byproduct materials (radioisotopes); source materials (uranium and thorium); and certain quantities of special nuclear materials. The mechanism for the transfer of NRC's authority to a State is an agreement signed by the Governor of the State and the Chairman of the Commission, in accordance with section 274b of the Act.
NRC assistance to States entering into Agreements includes review of requests from States for 274b Agreements, or amendments to existing agreements, meetings with States to discuss and resolve NRC review comments, and recommendations for Commission approval of proposed 274b agreements. Additionally, NRC conducts training courses and workshops; evaluates technical licensing and inspection issues from Agreement States; evaluates State rule changes; participates in activities conducted by the Conference of Radiation Control Program Directors, Inc.; and provides early and substantive involvement of the States in NRC rulemaking and other regulatory efforts. The NRC also coordinates with Agreement States the reporting of event information and responses to allegations reported to NRC involving Agreement States.
On March 26, 1962, the Commonwealth of Kentucky became the first Agreement State. In December 1964, the U.S. Atomic Energy Commission hosted the first annual joint meeting with a group of these States. Today, 37 States have entered into Agreements with NRC. The States of Wyoming and Vermont are currently pursuing Agreements with the NRC.
Atomic Energy Act of 1954, as Amended in NUREG-0980
This Act is the fundamental U.S. law on both the civilian and the military uses of nuclear materials. On the civilian side, it provides for both the development and the regulation of the uses of nuclear materials and facilities in the United States, declaring the policy that "the development, use, and control of atomic energy shall be directed so as to promote world peace, improve the general welfare, increase the standard of living, and strengthen free competition in private enterprise." The Act requires that civilian uses of nuclear materials and facilities be licensed, and it empowers the NRC to establish by rule or order, and to enforce, such standards to govern these uses as "the Commission may deem necessary or desirable in order to protect health and safety and minimize danger to life or property." Commission action under the Act must conform to the Act's procedural requirements, which provide an opportunity for hearings and Federal judicial review in many instances.
Under section 274 of the Act, the NRC may enter into an agreement with a State for discontinuance of the NRC's regulatory authority over some materials licensees within the State. The State must first show that its regulatory program is compatible with the NRC's and adequate to protect public health and safety. The NRC retains authority over, among other things, nuclear power plants within the State and exports from the State.
A major amendment to the Act established compensation for, and limits on, licensee liability for injury to off-site persons or damage to property caused by nuclear accidents.
§ 35.92 Decay-in-storage.
(a) A licensee may hold byproduct material with a physical half-life of less than or equal to 120 days for decay-in-storage before disposal without regard to its radioactivity if it—
(1) Monitors byproduct material at the surface before disposal and determines that its radioactivity cannot be distinguished from the background radiation level with an appropriate radiation detection survey meter set on its most sensitive scale and with no interposed shielding; and
(2) Removes or obliterates all radiation labels, except for radiation labels on materials that are within containers and that will be managed as biomedical waste after they have been released from the licensee.
(b) A licensee shall retain a record of each disposal permitted under paragraph (a) of this section in accordance with § 35.2092.
§ 35.2092 Records of decay-in-storage.
A licensee shall maintain records of the disposal of licensed materials, as required by § 35.92, for 3 years. The record must include the date of the disposal, the survey instrument used, the background radiation level, the radiation level measured at the surface of each waste container, and the name of the individual who performed the survey
§ 30.18 Exempt quantities.
(a) Except as provided in paragraphs (c) through (e) of this section, any person is exempt from the requirements for a license set forth in section 81 of the Act and from the regulations in parts 30 through 34, 36, and 39 of this chapter to the extent that such person receives, possesses, uses, transfers, owns, or acquires byproduct material in individual quantities, each of which does not exceed the applicable quantity set forth in § 30.71, Schedule B.
(b) Any person, who possesses byproduct material received or acquired before September 25, 1971, under the general license then provided in § 31.4 of this chapter or similar general license of a State, is exempt from the requirements for a license set forth in section 81 of the Act and from the regulations in parts 30 through 34, 36 and 39 of this chapter to the extent that this person possesses, uses, transfers, or owns byproduct material.
(c) This section does not authorize for purposes of commercial distribution the production, packaging, repackaging, or transfer of byproduct material or the incorporation of byproduct material into products intended for commercial distribution.
(d) No person may, for purposes of commercial distribution, transfer byproduct material in the individual quantities set forth in § 30.71 Schedule B, knowing or having reason to believe that such quantities of byproduct material will be transferred to persons exempt under this section or equivalent regulations of an Agreement State, except in accordance with a license issued under § 32.18 of this chapter, which license states that the byproduct material may be transferred by the licensee to persons exempt under this section or the equivalent regulations of an Agreement State.
(e) No person may, for purposes of producing an increased radiation level, combine quantities of byproduct material covered by this exemption so that the aggregate quantity exceeds the limits set forth in § 30.71, Schedule B, except for byproduct material combined within a device placed in use before May 3, 1999, or as otherwise permitted by the regulations in this part.
What is Superfund?
Thousands of contaminated sites exist nationally due to hazardous waste being dumped, left out in the open, or otherwise improperly managed. These sites include manufacturing facilities, processing plants, landfills and mining sites.
In the late 1970s, toxic waste dumps such as Love Canal and Valley of the Drums received national attention when the public learned about the risks to human health and the environment posed by contaminated sites.
In response, Congress established the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) in 1980.
CERCLA is informally called Superfund. It allows EPA to clean up contaminated sites. It also forces the parties responsible for the contamination to either perform cleanups or reimburse the government for EPA-led cleanup work.
When there is no viable responsible party, Superfund gives EPA the funds and authority to clean up contaminated sites.
Superfund’s goals are to:
· Protect human health and the environment by cleaning up polluted sites ;
· Make responsible parties pay for cleanup work ;
· Involve communities in the Superfund process ; and
· Return Superfund sites to productive use .
Superfund History
Since 1980, EPA's Superfund program has helped protect human health and the environment by managing the cleanup of the nation's worst hazardous waste sites and responding to local and nationally significant environmental emergencies. Below you will find a timeline highlighting some of the most notable milestones in the history of the Superfund and other cleanup programs. Click on the links for more information about a particular topic or event.
Superfund Success Stories
It′s easy to forget that there was a time in the United States when EPA lacked the legal authority to clean up hazardous waste sites like Love Canal, New York, or to respond to emergencies such as train derailments involving dangerous chemicals. Even though the EPA had been established for ten years, it was not until December 11, 1980, that President Jimmy Carter signed into law the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund). This historic new statute gave EPA the authority to clean up uncontrolled hazardous waste sites and spills.
Contaminants at Superfund Sites
Lead - Lead contamination at Superfund sites presents a threat to human health and the environment. This website describes EPA's approach to addressing those risks, and the challenges of remediating lead contamination at Superfund sites, and includes information on human health effects, lead risk assessment, software, user manuals, guidance, frequent questions, and technical assistance.
Asbestos - This page contains information regarding addressing asbestos contamination at Superfund sites, which includes policy and guidance, technical assistance, health effects, and naturally occurring asebestos.
Dioxin - Provides information on characterization of dioxin contaminated soil.
Soil Bioavailability - This Web area describes how EPA is incorporating relative bioavailability information for human exposures at Superfund sites exposed to soil contaminants via oral pathway.
Radiation - This page contains information regarding addressing radiation contamination at
Radiation at Superfund Sites
This page provides EPA remedial project managers with information and guidance on the cleanup of radioactive contamination at Superfund sites, including:
· Superfund radiation guidance and reports
· Risk Assessment
· Community Involvement
· Radiation reports from non-Superfund EPA programs and offices
· EPA's Memorandum of Understanding (MOU) with the Nuclear Regulatory Commission (NRC)
What is a Radiation Safety Committee?
The Radiation Safety Committee is responsible for policies and practices regarding the use of radioactive materials and radiation producing machines; to review all license applications and human use research protocols using radioisotopes or radiation producing machines for research purposes only. http://research.uthscsa.edu/safety/radiationcommittee.shtml
Subpart B--General Administrative Requirements
§ 35.24 Authority and responsibilities for the radiation protection program.
(f) Licensees that are authorized for two or more different types of uses of byproduct material under Subparts E, F, and H of this part, or two or more types of units under Subpart H of this part, shall establish a Radiation Safety Committee to oversee all uses of byproduct material permitted by the license. The Committee must include an authorized user of each type of use permitted by the license, the Radiation Safety Officer, a representative of the nursing service, and a representative of management who is neither an authorized user nor a Radiation Safety Officer. The Committee may include other members the licensee considers appropriate.
RMW
Regulated medical waste (RMW), also known as ‘biohazardous’ waste or 'infectious medical’ waste, is the portion of the waste stream that may be contaminated by blood, body fluids or other potentially infectious materials, thus posing a significant risk of transmitting infection. The following six medical wastes are commonly regulated by states:
· Pathological waste . Tissues, organs, body parts, and body fluids removed during surgery and autopsy.
· Human blood and blood products . Waste blood, serum, plasma and blood products.
· Cultures and stocks of infectious agents (microbiological waste). Specimens from medical and pathology laboratories. Includes culture dishes and devices used to transfer, inoculate, and mix. Also includes discarded live and attenuated vaccines.
· Contaminated sharps . Contaminated hypodermic needles, syringes, scalpel blades, Pasteur pipettes, and broken glass.
· Isolation waste . Generated by hospitalized patients isolated to protect others from communicable disease.
· Contaminated animal carcasses, body parts and bedding . From animals intentionally exposed to pathogens in research, biologicals production, or in vivo pharmaceuticals testing.
http://www.hercenter.org/rmw/rmwoverview.cfm
Detecting Radiation
Although many radioactive materials are silver-colored, metallic solids in their pure state, they can vary in color and exist in different physical states, including liquids and gases. They are also physically indistinguishable from other (nonradioactive) metals. In addition, ionizing radiation is not detectable by one's senses. It cannot be seen, heard, smelled, tasted, or felt. For these reasons, simple visual inspection is insufficient to identify radioactive materials, and radiation sources can be virtually impossible to recognize without special markings. To address these problems, scientists have developed the following four major types of instruments to detect and identify radioactive materials and ionizing radiation:
· Personal Radiation Detector (PRD)
· Radiation Isotope Identification Device (RIID)
· Radiation Portal Monitor (RPM)
Personal Radiation Detector (PRD)
A PRD is a wearable gamma and/or neutron radiation detector, approximately the size of a pager. When exposed to elevated radiation levels, the device alarms with flashing lights, tones, and/or vibrations. Most PRDs numerically display the detected radiation intentisty (on a scale of 0 to 9) and, thus, can be used to locate a radiation source; however, they typically are not as sensitive as handheld survey meters and cannot identify the type of radioactive source.
Handheld Survey Meter
As the name implies, the survey meter is a handheld radiation detector, which typically measures the amount of radiation present and provides this information on a numerical display in units of counts per minute, counts per second, or microroentgen (µR) or microrem (µrem) per hour. Most of these devices detect beta and gamma radiation only. However, some models can detect alpha, beta, gamma, and/or neutron radiation emitted from radioactive materials.
One particular meter, known as a teletector, is specifically designed to detect gamma and x-ray radiation. Named for its "telescoping" ability, this device can be extended to about 4 meters (13 feet) to measure very high dose rates without subjecting the user to unnecessary exposure. In addition, these devices typically have the ability to measure dose rates ranging from 0 to 1,000 rad per hour.
Survey meter
Any portable radiation detection instrument especially adapted for inspecting an area or individual to establish the existence and amount of radioactive material present
Radiation Isotope Identification Device (RIID
A RIID is a radiation detector with the ability to analyze the energy spectrum of radiation, in order to identify the specific radioactive material (radionuclide) that is emitting the radiation. In addition, these devices can be used as survey instruments to locate radioactive material.
Radiation Portal Monitor (RPM)
An RPM is a large pass-through radiation monitor (or "portal") for personnel, vehicles, container boxes, or trains. Typically, these devices consist of two pillars containing radiation detectors, which are remotely monitored from a display panel. These monitors alarm to indicate the presence of radioactive materials, including low-radiation materials like uranium.
Ionization Chamber
http://www.radiationanswers.org/radiation-introduction/detecting-measuring/ionization-chamber.html
An ionization chamber (or ion chamber) is often portable. An ion chamber is used to measure the rate of radiation exposure (how much radiation exposure is being received in a specified period of time). The ability of the ion chamber to measure the exposure rate from a radionuclide is based upon the ability of the emission to reach the active portion of the meter and the energy of the emission. Ion chambers are used where there is measurable exposure to or potential for measurable exposure to x and gamma rays.
Ionization chamber
An instrument that detects and measures ionizing radiation by measuring the electrical current that flows when radiation ionizes gas in a chamber, making the gas a conductor of electricity.
An ionization chamber measures the charge from the number of ion pairs created within a gas caused by incident radiation.[2] It consists of a gas-filled chamber with two electrodes; known as anode and cathode. The electrodes may be in the form of parallel plates (Parallel Plate Ionization Chambers: PPIC), or a cylinder arrangement with a coaxially located internal anode wire. A voltage potential is applied between the electrodes to create an electric field in the fill gas. When gas between the electrodes is ionized by incident ionizing radiation, Ion-pairs are created and the resultant positive ions and dissociated electrons move to the electrodes of the opposite polarity under the influence of the electric field. This generates an ionization current which is measured by an electrometer circuit. The electrometer must be capable of measuring the very small output current which is in the region of femtoamperes to picoamperes, depending on the chamber design, radiation dose and applied voltage. Each ion pair created deposits or removes a small electric charge to or from an electrode, such that the accumulated charge is proportional to the number of ion pairs created, and hence the radiation dose. This continual generation of charge produces an ionization current, which is a measure of the total ionizing dose entering the chamber. However, the chamber cannot discriminate between radiation types (beta or gamma) and cannot produce an energy spectrum of radiation.
LSC
Liquid Scintillation Counter
http://www.radiationanswers.org/radiation-introduction/detecting-measuring/liquid-scintillation.html
A liquid scintillation counter generally is not portable. Liquid scintillation counting is the most widely used technique for the detection and quantification of radioactivity. This measurement technique is applicable to all types of emissions, though it is most often used for beta particles. Liquid scintillation counting is an analytical technique that measures activity of radionuclides from the rate of light photons emitted by a sample.
Samples to be counted are prepared by adding a scintillation fluid (cocktail) to the beta emitter. As beta particles are released and interact with the fluid, photons of light are produced and measured. The intensity of the light is proportional to the energy of the beta particle; therefore, the spectra for different-energy beta emitters are somewhat unique.
https://www.nrc.gov/docs/ML1122/ML11229A718.pdf
A scintillating liquid, referred to as the “cocktail,” serves as the detector.
The cocktail (perhaps 10 ml) is inside a plastic or glass vial that is transparent to the light emitted by the cocktail. Ideally, the sample (e.g., 1 ml) is dissolved in the cocktail. Failing that, the sample might be suspended as an emulsion or suspended in a gel. In some cases, a large solid sample (e.g., a smear) is simply placed into the cocktail with no attempt at dissolving it.
Liquid scintillation counting is primarily used to quantify pure beta emitters, e.g., H-3, Ni-63, C-14, S-35, P-32
It is also used to quantify alpha emitters and nuclides that decay by electron capture (e.g., Fe-55, Cr-51, I-125). LSC incorporates elements of spectroscopy, but it is rarely used to identify radioactive material. As a rule, LSC is used to quantify the activity of a known nuclide
Three Important Characteristics of LSC:
1. High counting efficiency: 100% for many nuclides. Efficiencies as high as 70% for H-3
2. No backscatter
3. Low background
1. High Counting Efficiency
There are two reasons for the high counting efficiency:
• There is no window through which the radiation must pass in order to reach the sensitive part of the detector
• The system employs “four pi” geometry. No matter which direction the radiation is emitted in, it will interact with the cocktail (assuming we are talking about charged particle radiation).
2. No Backscatter
When proportional counters or GM detectors count beta particles, backscatter directs some betas towards the detector that otherwise would have gone in a different direction.
While this increases the detector counting efficiency, it makes our estimate of the counting efficiency less certain!
LSC involves no source support in which backscatter can occur.
3. Low Background
The LSC vials (glass or plastic) are made of materials with very low levels of naturally occurring radionuclides.
When positioned inside the counting chamber, the LSC vial is shielded from background rays Otherwise gamma rays. Otherwise, these gamma rays could interact with the vial wall or the cocktail (primarily via Compton scattering) and transfer their energy to electrons which could produce a signal indistinguishable from that produced by the betas being counted.The shield might be passive (e.g., lead) or active (e.g., an anticoincident BGO guard detector)
LSC systems use coincidence counting to reduce the number of spurious counts produced by electronic noise. When a beta particle is emitted in the cocktail, a single scintillation event (flash) occurs in which light photons are emitted in all directions.
The two photomultiplier tubes react to the scintillation at the same moment in time in coincidence) and each PMT generates a pulse that travels to the coincidence and summation circuits.
The coincidence circuit “recognizes” that this represents a legitimate decay event and it sends a logic pulse to the summation circuit telling it to sum the two pulses and open its electronic gate to allow the resulting pulse through.
Liquid scintillation counting theory
Liquid scintillation counting (LSC) is the standard laboratory method to quantify the radioactivity of low energy radioisotopes, mostly beta-emitting and alpha-emitting isotopes. The sensitive LSC detection method requires specific cocktails to absorb the energy into detectable light pulses. In order to efficiently transfer the emitted energy into light, LSC cocktails must consist of two basic components:
· The aromatic, organic solvent
· The scintillator(s) or fluors
As the majority of samples applied in LSC are aqueous-based, most of the LSC cocktails consist of:
· The aromatic, organic solvent
· The scintillator(s) or fluors
· The surfactants
Principle of LSC
After excitation of the aromatic solvent molecules through the energy released from a radioactive decay, the energy is next transferred to the scintillator (also sometimes referred to as the "phosphor" or "fluor"). The energy absorbed through the scintillators produces excited states of the electrons, which decay to the ground state and produce a light pulse characteristic for the scintillator. The light is detected by the photomultiplier tube (PMT) of the liquid scintillation counter.
Gamma Counter
http://www.radiationanswers.org/radiation-introduction/detecting-measuring/gamma-counter.html
A gamma counter often is not portable. Gamma counters do just as the name implies—quantify the activity of a gamma-emitting sample. In principle, the gamma counter is like a scintillation detector with the exception that with a gamma counter the scintillation crystal surrounds the sample. The gamma rays interact with the crystal, are absorbed, and produce light. As with the scintillation detector survey meter, if the energy of the interacting photons is too low, the photons of light that are produced may be absorbed in the scintillation crystal and never be detected. If the energy is too high, the incoming photons may just pass right through without interacting. The thickness of the crystal is critical and the efficiency of the instrument for detecting certain gamma-ray energies is dependent upon the thickness of the crystal
MDA- Minimum detectable activity
The Minimum Detectable Activity, or MDA, represents the smallest quantity of a radioisotope which can be detected with 95% confidence
Minimum Detectable Activity (MDA)
MDA is the minimum detectable (quantifiable) activity in dpm at a specified confidence level. Additional conversion factors (C) may be applied to convert dpm to any other activity units that may be desired (e.g., μCi, kBq, etc.). MDA depends on the counting device, counting times (controllable by procedure) and background counting rate. It is not specific to an individual sample. The MDA of a detection system can be prospectively established in the sample collection and counting procedure by specifying sample and background counting times, and by specifying some maximum acceptable background counting rate. Detector efficiency is established during calibration.
Where:
Rb = background count rate in cpm
ts = sample count time in minutes
tb = background count time in minutes
E = detector efficiency in counts per disintegration
A = area wiped
C = conversion factor from dpm to other desired activity unit, if applicable
k1= the one-sided confidence factor = 1.645 at 95% confidenceIn nuclear counting programs, MDA is usually calculated at the 95% confidence level (k1 = 1.645).
Geiger-Mueller counter
http://www.radiationanswers.org/radiation-introduction/detecting-measuring/geiger-mueller.html
A radiation detection and measuring instrument. It consists of a gas-filled tube containing electrodes, between which there is an electrical voltage, but no current, flowing. When ionizing radiation passes through the tube, a short, intense pulse of current passes from the negative electrode to the positive electrode and is measured or counted. The number of pulses per second measures the intensity of the radiation field. It was named for Hans Geiger and W. Mueller, who invented it in the 1920s. It is sometimes called simply a Geiger counter or a G-M counter and is the most commonly used portable radiation instrument. For related information, see Detecting Radiation.
Geiger-Mueller (GM) Meter
The GM survey meter is the most common device used for the detection of radioactive contamination. You might hear this meter referred to as a “pancake” or “GM pancake” because of the look of the device. A GM meter is often portable, and the efficiency of a GM for detecting radiation depends on four factors:
1. The type of radiation.
2. The energy of the radiation.
3. The amount of activity in the source.
4. The direction of the source relative to the instrument detector active area.
If a beta particle or gamma ray can enter the active portion of a GM meter and interact, it can be detected. Because the detection efficiency of the GM meter is dependent upon the energy of the particle or ray, the efficiency of a GM meter is much higher for detecting beta particles than it is for detecting gamma rays. Beta particles do not travel far, so if they are able to enter the active portion of the meter, they have a high probability of interacting and being detected. Gamma rays, on the other hand, have enough energy to enter the active portion, but may exit without interacting.
WHAT IS RADIATION?
Radiation is the process by which energy is emitted as either particles or waves. Broadly, it can take the form of sound, heat, or light. However, most people generally use it to refer to radiation from electromagnetic waves, ranging from radio waves, though the visible light spectrum, and up through to gamma waves.
ATOMS AND THEIR Parts
Most of the discussion about radiation, how it works, and what its effects are boil down to the interaction of radiation with atoms (and molecules) that it comes into contact with. Atoms form the basic building blocks of all matter. They consist of a nucleus, made of positively-charged protons (and sometimes neutrally-charged neutrons), and an outer cloud of electrons, which have a negative charge. The positive charge of a single proton is equal to the negative charge of a single electron.
Protons and neutrons have a relatively large size and atomic weight, whereas electrons are extremely small and light by comparison. Due to the nature of opposite charges attracting, atoms tend to have an equal number of protons and electrons, leaving the atom as a whole having a net charge of zero. However, if the atom either loses or gains an electron, it becomes an ion, and carries a charge.
It will seek bonds with other charged particles in order to regain a neutral balance, potentially leading to new molecules being formed.
IONIZING VS NON-IONIZING RADIATION
Radiation is generally classified ionizing or non-ionizing, based on whether it has enough energy to knock electrons off atoms that it interacts with, as well as being able to do lower-energy damage such as breaking chemical bonds in molecules. Ionizing radiation, which is caused by unstable atoms giving off energy to reach a more stable state, is more of a health threat to humans because it involves changing the basic makeup of atoms in cells, and more specifically the DNA molecules inside of cells. It does, of course, take a very strong dose of radiation to substantially damage a cell’s structure, as there can be trillions of atoms in a single cell.
The scale of electromagnetic radiation, broken down into categories of ionizing and non-ionizing radiation
Most non-ionizing radiation, such as radio and microwave energy, is considered harmful only to the extent of the amount of heat energy it transfers to whatever it hits. This is, in fact, the way that microwaves cook food. UV light is unique in that while it is non-ionizing, it does have the capacity to cause harmful effects similar to what ionizing radiation can create, such as an increased risk of cancer due to damage to DNA molecules.
How is radiation measured?
The radioactivity of a substance, or how “active” it is radioactively, is measured in either curies (Ci) or Becquerel’s (Bq). Both are measures of the number of decays per second, or how often an atom in a given sample will undergo radioactive decay and give off a particle or photon of radiation. The curie (1 Ci equals about 37,000,000,000 decays per second) is named after Marie and Pierre Curie, and is equal to roughly the activity of one gram of radium, which they studied. The Becquerel is the SI unit for radioactivity. One Bq equals one decay per second. The Bq is the SI unit, though the curie remains widely used throughout the US in both government and industry.
Types of Ionizing Radiation
Alpha, Beta, Gamma, X-Ray and Neutron Radiation
ALPHA, BETA, GAMMA, X-RAY, AND NEUTRON RADIATION
Ionizing radiation takes a few forms: Alpha, beta, and neutron particles, and gamma and X-rays. All types are caused by unstable atoms, which have either an excess of energy or mass (or both). In order to reach a stable state, they must release that extra energy or mass in the form of radiation.
Alpha Radiation
Alpha radiation: The emission of an alpha particle from the nucleus of an atom
Alpha radiation occurs when an atom undergoes radioactive decay, giving off a particle (called an alpha particle) consisting of two protons and two neutrons (essentially the nucleus of a helium-4 atom), changing the originating atom to one of an element with an atomic number 2 less and atomic weight 4 less than it started with. Due to their charge and mass, alpha particles interact strongly with matter, and only travel a few centimeters in air. Alpha particles are unable to penetrate the outer layer of dead skin cells, but are capable, if an alpha emitting substance is ingested in food or air, of causing serious cell damage. Alexander Litvinenko is a famous example. He was poisoned by polonium-210, an alpha emitter, in his tea.
Beta Radiation
Beta radiation: The emission of a beta particle from the nucleus of an atom
Beta radiation takes the form of either an electron or a positron (a particle with the size and mass of an electron, but with a positive charge) being emitted from an atom. Due to the smaller mass, it is able to travel further in air, up to a few meters, and can be stopped by a thick piece of plastic, or even a stack of paper. It can penetrate skin a few centimeters, posing somewhat of an external health risk. However, the main threat is still primarily from internal emission from ingested material.
Gamma Radiation
Gamma radiation: The emission of an high-energy wave from the nucleus of an atom
Gamma radiation, unlike alpha or beta, does not consist of any particles, instead consisting of a photon of energy being emitted from an unstable nucleus. Having no mass or charge, gamma radiation can travel much farther through air than alpha or beta, losing (on average) half its energy for every 500 feet. Gamma waves can be stopped by a thick or dense enough layer material, with high atomic number materials such as lead or depleted uranium being the most effective form of shielding.
X-Rays
X-Rays: The emission of a high energy wave from the electron cloud of an atom
X-rays are similar to gamma radiation, with the primary difference being that they originate from the electron cloud. This is generally caused by energy changes in an electron, such as moving from a higher energy level to a lower one, causing the excess energy to be released. X-Rays are longer-wavelength and (usually) lower energy than gamma radiation, as well.
Neutron Radiation
Neutron radiation: The emission of a neutron from the nucleus of an atom
Lastly, Neutron radiation consists of a free neutron, usually emitted as a result of spontaneous or induced nuclear fission. Able to travel hundreds or even thousands of meters in air, they are however able to be effectively stopped if blocked by a hydrogen-rich material, such as concrete or water. Not typically able to ionize an atom directly due to their lack of a charge, neutrons most commonly are indirectly ionizing, in that they are absorbed into a stable atom, thereby making it unstable and more likely to emit off ionizing radiation of another type. Neutrons are, in fact, the only type of radiation that is able to turn other materials radioactive.
Exposure
Absorption of ionizing radiation or ingestion of a radioisotope. Acute exposure is a large exposure received over a short period of time. Chronic exposure is exposure received over a long period of time, such as during a lifetime. The National Council on Radiation Protection and Measurements (NCRP) estimates that an average person in the United States receives a total annual dose of about 0.62 rem (620 millirem) from all radiations sources, a level that has not been shown to cause humans any harm. Of this total, natural background sources of radiation—including radon and thoron gas, natural radiation from soil and rocks, radiation from space and radiation sources that are found naturally within the human body—account for approximately 50 percent. Medical procedures such as computed tomography (CT scans) and nuclear medicine account approximately for another 48 percent. Other small contributors of exposure to the U.S. population includes consumer products and activities, industrial and research uses, and occupational tasks. The maximum permissible yearly dose for a person working with or around nuclear material is 5 rem. For additional detail, see Doses in Our Daily Lives and Measuring Radiation.
Dose
A general term, which may be used to refer to the amount of energy absorbed by an object or person per unit mass. Known as the “absorbed dose,” this reflects the amount of energy that ionizing radiation sources deposit in materials through which they pass, and is measured in units of radiation-absorbed dose (rad). The related international system unit is the gray (Gy), where 1 Gy is equivalent to 100 rad. By contrast, the biological dose or dose equivalent, given in rems or sieverts (Sv), is a measure of the biological damage to living tissue as a result of radiation exposure. For additional information, see Doses in Our Daily Lives and Measuring Radiation.
A common misconception is the idea that exposure to radiation in turn makes someone radioactive. This is, usually, not the case. It’s important, then, to understand the differences between radiation, and radioactivity.
What does it mean to be radioactive?
https://www.mirion.com/introduction-to-radiation-safety/radiation-vs-contamination/
An atom is said to be “radioactive” if it is unstable due the excess of either energy or mass, and is therefore likely to decay at some point and give off radiation. A substance or material is said to be “radioactive” if it is made up of or contains a large quantity of a radioactive material. These radioactive materials, such as bananas, the uranium glaze in vintage fiestaware, or NORM generated in the process of natural gas exploration, give off radiation over time as the radioactive atoms in them decay.
Uranium Ore, a naturally radioactive substance
Over time, as the number of unstable atoms decreases, the material becomes less radioactive. This time is measured by the “half life” of different radioactive elements. This is the amount of time it takes for half of the atoms in a given sample to decay and give off radiation. For example, carbon-14 has a half-life of 5730 years, so after that amount of time, a quantity of 100 atoms of C-14 would have turned into 50 C-14 atoms and 50 Nitrogen-14 atoms. Iridium-11, a radioactive isotope used in medicine as a tracer, has a half-life of 2.8 hours; whereas another isotope of iridium at the other end of the scale, iridium-115 has a half-life of 441 trillion years. It’s commonly held that a sample of radioactive material will be completely decayed after 7 half lives, though after that time there would still be about 0.78% left, which with a large enough starting sample would still be significant. For smaller samples like those typically used in medicine, though, it’s a good rule of thumb.
What is contamination?
Put simply, radioactive contamination is just radioactive material somewhere it shouldn’t be. This could be anything from nuclear fallout from a dirty bomb (the whole purpose of which would be to disperse radioactive contaminant), to a lab worker splashing some of a radioactive solution on his pants and taking them home. The most common source of contamination is from mistakes or accidents in the production of radionuclides, like those used in the medical field.
Pripyat in Ukraine had to be abandoned after the Chernobyl accident due to the high amount of radioactive contamination
Contamination on or in a surface can be either “fixed” or “removable.” An example of fixed contamination, or contamination that isn’t able to be removed, would be in metal recycling: If a batch of recycled metal included something with radioactive material in it, the final product would have that radioactive material mixed in and permanently part of it. Removable contamination is, of course, removable, such as a loose powder or something that can be cleaned and safely disposed of. Disposal of radioactive waste can consist of reprocessing it for commercial use, though in some cases where this isn’t possible the best solution is burying it in concrete, rock, as this helps prevent the spread of the contamination any further.
Does being exposed to radiation make me radioactive?
Exposure to radiation does not immediately make a person radioactive. The only type of radiation that is capable of directly causing other material to become radioactive is neutron radiation, which is generally only found inside nuclear reactors or in a nuclear detonation. Anyone in those conditions is, put plainly, going to have bigger problems.
CT Scans and other routine medical procedures expose someone to radiation without leaving that person radioactive afterward
However, the ingestion of radioactive material does have the potential of making a person radioactive, at least on a temporary basis. This is the principle behind the medical use of many radioactive materials, as it aids in imaging, diagnosis, and other areas. Between the short half-lives of the elements involved and the body’s natural means of disposing of many radioactive elements, a person’s individual radioactivity is usually short-lived. However, certain types of contamination, depending on the isotopes involved and the availability of treatment, can become more permanently deposited in a person’s organs or bones.
