Information about source points of anthropogenic radioactivity
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SECTION 4: DEFINITIONS AND CONVERSION FACTORS
This section is sub-divided into three sections. If you don't find the definition you are looking for in the first section, please refer to the following ones. All definitions are listed in alphabetical order within the sections.
A. Basic definitions
B. Definitions and acronyms pertaining to biological monitoring of anthropogenic radioactivity (source points and accidents)
C. Conversion factors and other useful information
|A. Basic Definitions|
ACTIVATION PRODUCTS: nuclides formed through transformation of stable reactor components into radioactive isotopes after intense bombardment with fission products. Radioactivity is thus induced through neutron bombardment or other types of radiation in reactor vessel components and corrosion products (and also in weapons casings) which were stable before the reactor vessel went on-line. The transuranic nuclides plutonium, americium, curium, etc., are also neutron activation products, originating from neutron capture in uranium nuclides rather than from the fission of these nuclides. Other important activation products include carbon-14 and tritium as well as activation products derived from activated stainless steel and carbon steel, activated sludge, corrosion deposits and concrete, and contaminated building products e.g. 55Fe, 54Mn, 65Zn, 58Co and 60Co. An additional listing of activation products and corrosion products can be found after the checklist of biologically significant nuclides (see RADNET Section 5).
BECQUEREL (Bq): a less unwieldy measurement of radioactivity than curies: one disintegration per second (d.p.s.). A picocurie is 0.037 d.p.s. or 0.03 Bq. The most common reporting unit outside the United States for radionuclide air concentrations is µBq/m3 (microbecquerels).
CRUD: "...an acronym for 'Chalk River Unidentified Deposits.' ...black, highly radioactive substances found on the inside of piping and components at the Chalk River nuclear reactor ... CRUD has now become a standard industry term referring to minute, solid, corrosion products that travel into the reactor core, become highly radioactive, and then flow out of the reactor into other systems in the plant. ... CRUD can settle out in crevices or plate-out on the inside of piping in considerable quantities ... The major components of CRUD are iron, cobalt, chrome, and manganese ... CRUD is a concentrated source of radiation and represents a significant radiological risk because of its insolubility." (United States Federal Energy Regulatory Commission, Testimony of James K. Joosten, September 15, 1997, pg. 13-14).
CURIE: a measurement of radioactivity: the amount of radioactive material giving off 3.7 x 1010 d.p.s., or 37 billion disintegrations per second. In the United States, the picocurie (1 pCi = 0.037 d.p.s. or 1 x 10-12 of a curie) is the unit used for many measurements of radioactive contamination.
ELECTROMAGNETIC RADIATION (E.M.R.): energy radiated in the form of a wave which can accelerate charged particles. Electromagnetic radiation can travel through a vacuum. Its energy varies greatly; radio waves have the longest wavelengths and the lowest frequency and energy (1.2398 x 10-10 to 1.2398 x 10-5electron volts. X-rays and gamma rays have the shortest wavelengths and highest frequencies and energies (up to and above 6 x 106 electron volts). For a comprehensive explanation of the public health consequences of ionizing radiation, i.e. electromagnetic radiation above 155 ev, see Gofman, 1981, Section 10.
FISSION: a process, which, along with fusion, releases energy stored in separated nuclei. During fission, a fissionable nucleus such as plutonium absorbs a neutron, becomes unstable and splits into two nuclei, releasing energy. Nuclear power is a controlled, self-sustaining fission process; nuclear explosions are an uncontained chain reaction version of the fission process. In the detonation of thermonuclear (fusion or hydrogen) bombs, the fission process is the trigger for the more powerful fusion event. Fission products are the artificial radioactive offspring of nuclear industries and accidents; their inventories and pathways in the environment are the subject of this Website (Also see activation products, and naturally occurring radiation).
Gamma Camera: Remotely operated gamma ray imaging system that generates photos showing radiation areas within the hot side of a nuclear power plant, fuel reprocessing facility or other nuclear installation. The gamma camera is particularly useful during decommissioning and remediation activities for identifying major hot spots in equipment such as reactor vessels, steam generators, or reactor water systems which may contribute to worker exposure.
Greater Than Class C (GTCC): low-level waste disposal criteria specified by the NRC based on concentration of radionuclides (classes A, B and C) that exceed the low-level waste limits for class C and that are used to designate the waste as generally unacceptable for near-surface disposal. (BEMR, June 1996, pg. GL-4).
HIGHLY ENRICHED URANIUM: uranium with more than 20 percent of the 235U isotope, used for making nuclear weapons and also as fuel for some isotope production, research and power reactors. Weapons grade uranium is a subset of this group. (BEMR, June 1996, pg. GL-4).
IONIZING RADIATION: radiation with energy above 155 ev which has the ability to knock other electrons out of the orbits of atoms and molecules, often creating more ionizing radiation and adversely affecting living tissues. Biologically significant radiation is an ionizing dose of radiation above 155 ev which may have carcinogenic, mutagenic, or teratogenic health effects in humans.
ISOTOPES: forms of the same chemical element that differ only by the number of neutrons in their nucleus. Most elements have more than one naturally occurring isotope. Many isotopes have been produced in reactors and scientific laboratories. (BEMR, June 1996, pg. GL-5).
NATURALLY OCCURRING RADIATION: cosmogenic (extraterrestrial) and terrestrial radiation usually but not always with an activity range of 5-10 micro roentgens per hour (µRh-1), and having the same biological consequences as artificial radiation (fission and activation products). Radon (1/2T = 3.82 d), one of many naturally occurring radionuclides, has been recently recognized as a significant source of exposure particularly in well insulated homes overlying geological formations which produce large quantities of radon within the uranium decay series. Radon achieves biological significance when inhaled if, instead of being exhaled, it decays into four short-lived nuclides followed by the long-lived 210Pb; all of which are surface seeking particulates which become lodged in the lung. The daughter products in the uranium-radon decay series then become the source of the radiation dose from radon.
The term "naturally occurring" needs to be differentiated from "background radiation," which now includes the impact of the cumulative deposition from stratospheric fallout and nuclear accidents such as Chernobyl. In some contaminated areas, such accumulations of long-lived artificially produced radionuclides exceed natural background radiation levels. The term "background radiation," particularly when used by spokespersons for nuclear industries, can no longer be equated with the natural radiation background as it was before the advent of the nuclear age.
NUCLEAR FUEL CYCLE: the primary source of the anthropogenic radionuclides documented in RADNET. The nuclear fuel cycle, which includes the WEAPONS PRODUCTION CYCLE, has eight primary components, all of which result in the accumulation or release of significant quantities of radioactivity. The cycle begins with the exploitation of a naturally occurring radionuclide, uranium-238. The resulting contamination is "anthropogenic" in that it derives from human activities. The nuclear fuel cycle involves the following steps:
PLUME: the concentration profile of an airborne or waterborne release of material as it spreads from its source. (Center for Disease Control (CDC), Savannah River Site (SRS) dose reconstruction, 1999).
RADIOACTIVE HALF-LIFE (1/2T): the time required for one half the atoms in a radioactive substance to decay. For example, the radioactive half-life of cesium is 30.174 years, 1/2T = 30.174 y. Radionuclides with short half-lives are hot, emitting large amounts of radiation but decaying quickly and contrast with radionuclides with longer half-lives whose energy is emitted over a longer period of time. The biological half-life is the time required for the body to eliminate 1/2 of a radioactive substance by regular physiological processes of elimination. This definition differs slightly from effective half-life which is the time required for 50% of the radioactive contamination to be diminished by both radioactive decay and biological elimination.
RADIOACTIVITY: spontaneous decay of the nucleus of an atom by the emission of particles, usually accompanied by electromagnetic radiation. It is also defined as the mean number of nuclear transformations occurring in a given quantity of radioactive material per unit time, expressed in either becquerels (Bq) or curies (Ci). Most radionuclides (radioactive nuclides in contrast to stable nuclides) have multiple forms of radioactive emissions, and are classified according to their principal decay modes. The most common types of radiation are:
BETA RADIATION: e.g. emitted by tritium: a high speed electron, small in mass, moderate penetrating abilities, e.g. unable to penetrate more than a few millimeters of biological tissue.
GAMMA RADIATION: e.g. emitted by zirconium-95: electromagnetic radiation; highly penetrating, very energetic x-rays emitted by an excited nucleus. Will often but not always exit living tissues without depositing its biologically significant electron voltage (ev).
In the European community, a different set of reporting units are used as a component SI system (see definition of "becquerel"). The most common reporting units are Bq/kg for contamination of sediment and the biotic environment and microbecquerels per cubic meter (µBq/m3) for air concentration. The use of the cubic meter, a large reporting unit, allows observation of small changes in air concentrations which might be indicative of an active source point whose effluents are much more difficult to detect when the smaller reporting unit of µCi/mL, often utilized by the DOE, is used. (1 mL = 1 millionth of a cubic meter). Organizations, such as the DOE, responsible for environmental remediation in locations where hundreds of millions to billions of curies of radioactive wastes have been released to the natural environment, find it very useful to employ the smaller reporting unit which helps in obfuscating changing levels of environmental radiation.
SOURCE TERM: the quantity, chemical and physical form and time history (release duration) of contaminates released to the environment from a facility. (Center for Disease Control (CDC), Savannah River Site (SRS) dose reconstruction, 1999). Also see source term release.
TRANSURANIC ELEMENTS: all elements beyond uranium on the periodic table, that is, all elements with a number greater than 92. All transuranic elements are manmade. They include neptunium, plutonium, americium and curium. (BEMR, June 1996, pg. GL-9).
TRANSURANIC WASTE: waste material contaminated with 233U and its daughter products, certain isotopes of plutonium, and nuclides with an atomic number greater than 92 (uranium); each with half-lives greater than 20 years and in concentrations of more than one ten-millionth of a curie per gram of waste. It is produced primarily by reprocessing spent fuel, by using plutonium to fabricate nuclear weapons and during commercial nuclear electricity production. (BEMR, June 1996, pg. GL-9).
TRANSURANIUM NUCLIDES: elements of a higher atomic number than uranium (92), most transuranic isotopes are highly toxic alpha-emitting radionuclides with great biological significance which do not occur naturally in any significant quantities, but which are an artificial product of the fission process and emit radiation having much higher energy than other radionuclides which are also produced in the fission process; e.g. tritium, carbon-14 and strontium-90 . The transuranic nuclides of the greatest significance are neptunium-237, plutonium-238, 239, 241, americium-241, and curium-242, 244 (See checklist of biologically significant radionuclides).
TRITIUM: the heaviest isotope of the element hydrogen. It is three times heavier than hydrogen. Tritium gas is used to boost the explosive power of most modern nuclear weapons and has a half-life of over 12 years.
URANIUM: the basic material for nuclear technology. It is a slightly radioactive naturally occurring heavy metal that is more dense than lead. Uranium is 40 times more common than silver. (BEMR, June 1996, pg. GL-9).
VITRIFICATION: the process by which waste is transformed from a liquid or sludge into an immobile solid that traps radionuclides and prevents waste from contaminating soil, ground water and surface water. (BEMR, June 1996, pg. GL-10).
VOC: Volatile Organic Compounds. The generic name
for a variety of toxic chemicals utilized in the reprocessing of spent
nuclear fuel as well as in other industrial applications pertaining to
weapons production. The principal chemicals of interest include: trichloroethylene,
carbon tetrachloride, benzene, acetone, toluene, methalene chloride, xylenes,
chlorobenzene, naphthalene, etc. etc. These and other chemicals characterize
the hydrologic plumes of weapons production derived wastes now being monitored
in confined and unconfined aquifers at many U.S. weapons production facilities.
The large quantities of VOC's released to surface water supplies and evaporating
ponds and pits were subject to rapid evaporation and redistribution as
chemical fallout; only those VOC's which seeped into the soil and underlying
aquifers, or which were deliberately released as shallow well or deep well
injections, remain in the underground plumes now a component of DOE environmental
remediation efforts and USGS ground water monitoring programs. See RAD
11: Sections 1 and 5: major plume source points. See especially the
citations documenting the Hanford and Savannah River plumes.
|B. Definitions and acronyms pertaining to biological monitoring of anthropogenic radioactivity (source points and accidents)|
Agency for Toxic Substances and Disease Register (ATSDR): THE ATSDR was established as a component of the Superfund Act of 1980 (CERCLA) and has the mission of preparing toxicological profiles for hazardous substances most commonly found at facilities on the CERCLA National Priorities List. The ATSDR recently issued a draft for public comment of Toxicological Profile for Ionizing Radiation and is a well-spring of important information on toxic substances in general.
Airborne Multisensor Pod System (AMPS): A recent technological innovation for the collection of multisensor data for a variety of national security purposes. One component of remote sensing efforts, the AMPS is of particular interest because one of the pods to be used in aircraft utilizing this system will have high resolution spectral analysis capabilities pertaining to ground deposition of radioactivity deriving from nuclear accidents and nuclear waste plume source points. The following acronyms are of interest in defining and understanding remote sensing technologies which relate to radiological surveillance programs.
BIOINDICATORS: biological media which are the most susceptible to the accumulation of biologically significant radionuclides. Many bioindicators are in pathways to human consumption, allowing rapid transfer of radioactivity from the abiotic environment (air, precipitation, freshwater, sea water, soil and marine sediments) to sentinel organisms as well as crops and crop products such as milk, cheese and meat. Most pathway analyses for the ecological cycling of radionuclides begin with soil or sediment as the repository of radioactive contamination. The process by which living organisms absorb radioactive contamination is called bioaccumulation; bioaccumulation may also be defined as the assimilation of contamination prior to its movement up the food chain. Among the most significant bioindicators are:
CERCLA: Comprehensive Environmental Response, Compensation, and Liability Act. A federal law enacted in 1980 that governs the cleanup of hazardous, toxic, and radioactive substances. The Act and its amendments created a trust fund, commonly known as Superfund, to finance the investigation and cleanup of abandoned and uncontrolled hazardous waste sites. (BEMR, June 1996, pg. GL-2).
CHARACTERIZATION SURVEY: a type of survey that includes facility or site sampling, monitoring and analysis activities to determine the extent and nature of contamination. (MARSSIM, pg. GL-3).
CHELATION: the process by which both naturally occurring and artificial agents can be used as sequestering agents, thereby making radionuclides and other chemicals in a particular media available for transfer to another environment. Artificial chelating agents such as EDTA have a wide variety of industrial uses, and are often used to remove radioactive contamination. Unfortunately, natural chelating agents and chelating processes make plutonium oxide from stratospheric fallout and nuclear accidents which is usually in a biologically unreactive state in soils and sediment much more biologically available for uptake in pathways to human consumption. Almost no information is available about the long-term mobilization of plutonium isotopes by naturally occurring chelating agents (See Hanson, 1980, Section 10).
CONCENTRATION RATIOS: the tendency for many radionuclides to uniformly migrate in one proportion or another in various media in the biotic and abiotic environments. Sediment is the repository of radioactive fallout in abiotic media and thus the point of origination for many pathway analyses. Biological media either concentrate radionuclides as they pass through water to sediment or concentrate radionuclides after they have been remobilized from sediment by various biogeochemical processes (water = 1).
DAUGHTER PRODUCTS: a synonym for decay products, resulting from the radioactive disintegration of a radionuclide. Daughter products can either be stable or radioactive. Many important radionuclides are components of other nuclides' decay series: e.g. niobium-95 is a decay product of zirconium-95; neptunium-237 is a decay product of americium-241; americium-241 is a decay product of plutonium 241. Plutonium-238, the third most common constituent in spent fuel, is a decay product of neptunium 238. All curium nuclides decay to plutonium isotopes. Also called "growing in." An important daughter product of ubiquitous gaseous stack releases of nuclear reactors is 134Cs, a daughter product of 133Xe.
DECAY IN STORAGE (DIS): An idea whose time has not yet come: instead of dumping virtually uncontained 137Cs (1/2 T = 30 yr) and other intermediate-level wastes into near surface landfills, these wastes would be stored onsite at their point of generation for periods of 50 to 300 years. Now widely accepted by the European community as the only viable waste storage option for intermediate wastes, DIS is only coming to the US as a result of failure of the US government to develop a viable waste disposal policy for high-level wastes. As ISFSIs are constructed for spent fuel, it's only a small step to expand these facilities to add intermediate-level waste storage including GTCC wastes.
DOSE RECONSTRUCTION: a study process in which historical information is used to estimate the amounts of toxic materials released from a facility, how the materials could have moved offsite and the exposure of the public to those materials. Dose reconstruction involves past releases, not present or future releases. (Center for Disease Control (CDC), Savannah River Site (SRS) dose reconstruction, 1999).
EFFECTIVE ACTION LEVEL (FDA): Following the Chernobyl accident, the Food and Drug Administration implemented an unofficial protection action guideline when it observed high levels of Chernobyl-derived radiocesium contaminating imported foods approximately one year after the accident. THe FDA seized and destroyed foods contaminated in excess of 10,000 pCi/kg (370 Bq/kg) thereby setting an EFFECTIVE ACTION LEVEL which was significantly more conservative (lower) than the protection action guidelines promulgated by various U.S. government agencies before and after the Chernobyl accident. See RAD 6 for a more complete description of the wide variety of protection action guidelines.
EXPOSURE PATHWAY: the route that links radioactive contamination from a specific source point to a receptor population in a specific ecosystem.
Formerly Utilized Sites Remedial Action Program (FUSRAP): a federal program initiated in 1974 to identify and remediate sites around the country that were contaminated during the 1940's and 1950's as a result of researching, developing, processing and producing uranium and thorium and storing processing residues. (BEMR, June 1996, pg. GL-4).
FRENCH DRAINS: Chemical disposal wells utilized between 1945 and the late 1960's at most US weapons productions facilities involving fuel fabrication and spent fuel reprocessing. These wells were utilized for the quick and convenient disposal of highly toxic mixed waste streams which included large quantities of radioactive effluents mixed with volatile organic compounds (VOC's). For national security reasons no (known) recordkeeping was maintained of the volume or curic content of the mixed wastes disposed of by this method. The resulting plumes, many in either perched aquifers or in underlying aquifers, are frequently referenced in the DOE BEMR as well as in the extensive groundwater surveys of the USGS.
FUEL CLADDING FAILURE: The most probable kind of nuclear accident (as in "probabilistic risk assessment") and one that characterizes the operations of most nuclear reactors. Cladding failure begins with pin hole leaks that release some of the gasses within the fuel rods (called gap release; 3H, noble gasses, gaseous 131I are the most common stack effluents.) The most common cause of fuel failure is (fuel assembly) grid-to-(fuel)rod fretting that results from (a) vibrations within the reactor containment (b) differences in pressure caused by use of different types of fuel and (c) deformations in or damage to fuel assembly grids that then result in fuel failure which allows the spread of spent fuel pellets throughout the reactor containment. As fuel ages and undergoes long periods of burnup, it becomes much more vulnerable to fuel failure. Fuel failure can also result from defects in the manufacture of fuel rods; in the early days of the nuclear industry, aluminum cladding resulted in frequent fuel cladding failure in both DOE weapons production reactors and facilities such as the notorious Connecticut Yankee reactor at Haddam Neck. The cumulative effect of fuel cladding failure at CT Yankee constitutes the largest known accident since the Three Mile Island LORCA. The NRC has made every effort to cover-up the ubiquitous nature of fuel cladding failure by labeling all failure as "leakage" and then asserting that this is a normal part of reactor operations. A more truthful way of stating the matter is that fuel failure is the most probable form of nuclear accident and can range from a few failed rods with small openings to large numbers of failed rods including those which split open and spill their entire contents in the reactor containment. What happens to the spilled fuel pellets after their release from the failed fuel rods is one of the most important issues facing the nuclear industry as it decommissions its aging reactors. For more information on the relatively small fuel failure accident at MYAPC see RAD12-5E: Maine Yankee Decommissioning Debacle: Decommissioning Chronicle Continued (January 1999 onward).
HISTORICAL SITE ASSESSMENT (HSA): a detailed investigation to collect existing information, primarily historical information, on a site and its surroundings. (MARSSIM, pg. GL-8).
HOT PARTICLES: air-borne particles of partly volatilized fuel from nuclear accidents or from defective fuel cladding which can also be carried by liquid effluents. Hot particles from leaking reactor fuel are also known as "fuel fleas" because they become electrically charged as a result of radioactive decay and "hop" from one surface to another. Typical hot particles are ~10 µm in size and can contain nuclides ranging from activation products to reactor derived fission products (e.g. 95Nb, 95Zr, 103,106Ru, 141,144Ce, etc.) which were widely dispersed after the Chernobyl accident. (For a bibliography of articles on Chernobyl derived hot particles, see RADNET Section 10.) CRUD is another type of hot particle.
INDICATOR NUCLIDES: The principle radioactive products of nuclear industries or accidents. In the first few days of a nuclear accident, radioiodine-131 dominates the activity release profile. Other longer-lived radionuclides such as 106Ru, 137Cs, 239Pu dominate the later time compartments of the release pulse, producing exposure long after media coverage of a nuclear accident has faded and radioiodine-131 levels have subsided (See plume pulse pathways, RADNET Section 7). Cesium-137 is the most significant of the many nuclides which remain after the short-lived radionuclides have decayed.
"IRON FENCE": the most restricted alternative case for land use. It is characterized by containing, rather than actively remediating, contaminated sites. This means that soil and buried waste sites would be capped, ground-water contamination would be controlled from spreading by hydraulic controls and barriers, and facilities would be entombed. (BEMR, June 1996, pg. GL-5).
INDEPENDENT SPENT FUEL STORAGE INSTALLATION (ISFSI): These are onsite dry cask storage facilities built at nuclear reactors to hold spent fuel when the spent fuel pool gets too full. ISFSIs are one of the expensive and unfortunate consequences of the failure of the federal government to develop a safe and practical way to dispose of spent fuel wastes. Another word for the term ISFSI could be monitored retrievable storage, the only probable future solution to storing intermediate and high-level wastes that is safe, economical, politically viable, practical and likely to provide jobs for the next 10,000 years to former employees of nuclear power reactors and their descendants.
LIFE CYCLE COST ESTIMATE: a term used by the Department of Energy to designate the cost of complete remediation of weapons production facilities within the Environmental Management program. This term also applies to the decommissioning of nuclear power facilities. It may also be used in reference to the life cycle disposal costs of specific components in a contaminated site, e.g. spent fuel from a nuclear power plant, GTCC reactor vessel wastes, etc.
LORCA (LOSS OF REACTOR COOLANT ACCIDENT): LORCAs occur when the cooling water in the reactor containment drops below the level of the fuel and the fuel overheats and melts. A LORCA can result in a catastrophic accident if enough overheating occurs and the containment fails. Three Mile Island is the most well known example of a LORCA in the United States. The accident was discovered in enough time to halt the melting process. Most of the radioactivity released in this accident remains within the reactor containment. It appears that the NRC does not yet have an accurate understanding of how much radioactivity was released due to this accident.
NATIONAL IMAGERY AND MAPPING AGENCY (NIMA): Established within the Department of Defense on October 1, 1996 as a component of the US intelligence community, NIMA represents a consolidation of previously existing intelligence agencies into one centralized agency. NIMA incorporates the Defense Mapping Agency, the Central Imagery Office (CIO), and other agencies as well as the functions of the CIA's National Photographic Interpretation Center. Also incorporated in NIMA are the imagery processing elements of the Defense Intelligence Agency, the National Reconnaissance Office (NRO), and the Defense Airborne Reconnaissance. All these agencies are of particular interest with respect to radiological monitoring because they incorporate sophisticated remote sensing technologies, including remote sensing of spectral data that document the plume pulse movement of nuclear accidents-in-progress. Up to October 1, 1996, much of the remote sensing data of interest to RADNET had been collected by the NRO and collated by the CIO (until recently the existence of both of these offices had been classified information). The remote sensing data which documents the plume pulse movement of nuclear accidents-in-progress (and the presence of any above ground source point) is still classified information. Most remote sensing data in the electromagnetic energy spectrum between ultraviolet and microwave regions is becoming available to the general public through electronic means; only spectral data pertaining to national security concerns (nuclear data) remains classified (+155 Mev). How long can the intelligence community keep their fingers in the dike? RADNET warning: any person disseminating classified information is subject to prosecution and maximum sentence of life imprisonment. For more information on remote sensing technologies, visit RAD 13: RADLINKS: Part II-D: 1. US Intelligence Community Links and 2. US Department of Energy Laboratory Servers. See especially Sandia National Laboratory, Argonne National Laboratory, Pacific Northwest Laboratory and the Lawrence Livermore National Laboratory. Visitors to these sites will quickly discover the obstacle of "access denied"; nonetheless, the remote sensing technologies pertaining to radiological surveillance are often referenced in these sites.
NATIONAL PRIORITIES LIST: The EPA's list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial action under the CERCLA. (BEMR, June 1996, pg. GL-6).
NEUTRON SOURCE: The catalyst needed to begin a chain reaction at a nuclear power plant. After a few months, the neutrons emitted by irradiated fuel continue the chain reaction. Neutron sources eventually are removed from the core and end up in the spent fuel pool and constitute one more component of "orphan" high-level waste (not spent fuel and not high-level waste either.)
NUCLEAR WEAPONS COMPLEX: the chain of foundries, uranium enrichment plants, reactors, chemical separation plants, factories, laboratories, assembly plants and test sites that produced nuclear weapons. Sixteen major U.S. facilities in 12 states formed the nuclear weapons complex. (BEMR, June 1996, pg. GL-6).
PEAK CONCENTRATION / MEAN CONCENTRATION: the peak concentration is the highest reading in a series of samples; the mean concentration is the average of readings in a series of samples.
RADIOLYSIS: a process by which radioactivity breaks down and hence changes chemical compounds. It is a principal cause of certain kinds of waste management problems, notably in relation to liquid radioactive wastes and wastes containing mixtures of radioactive materials and non-radioactive chemicals. Chemicals present in the waste break down over time due to the action of radiation unless they are in very stable forms. The breakdown products in turn create new chemical reactions with each other and with pre-existing chemicals. These processes make estimation of the chemical make-up of the waste very difficult. They also frequently result in the generation of hydrogen gas. (Science for Democratic Action, January 1999, pg. 21).
RADIOMETRIC SURVEY: a radiological survey of a contaminated site, especially sediments, soil or other media containing sufficient data points to characterize the spread of contamination from a particular source point isometrically, i.e. via contour maps using isopleths which express the values of the data points. Aerial radiometric surveys have been utilized since the 1950's to characterize oil bearing geological formations; by the defense department for analyses of Russian and other weapons production facilities, and after the Chernobyl accident to characterize fallout in Russia, Sweden and England.
RESIDUAL CONTAMINATION STANDARDS: the amount and concentrations of contaminants in soil, water and other media that will remain following environmental management activities. (BEMR, June 1996, pg. GL-8).
RESOURCE CONSERVATION AND RECOVERY ACT (RCRA): a federal law enacted in 1976 to address the treatment, storage and disposal of hazardous waste.
RUBBLE-IZATION: The most recent NRC and nuclear industry technique for decommissioning nuclear reactors, rubble-ization is the deconstruction and onsite burial of reactor constituents such as the dome and other concrete structures as well as slightly to moderately contaminated steel beams and other equipment. This option is now well within dose based regulatory requirements for decommissioning nuclear reactors, and is currently proposed for decommissioning Maine Yankee Atomic Power Company in Wiscasset, Maine, as well as other New England reactors. There are now no volumetric contamination guidelines that would prevent onsite burial of reactor components possibly even including highly radioactive reactor vessels and their contents provided sufficient quantities of uncontaminated topsoil are utilized to block the shine from the contaminated burial site. Current NRC regulations now theoretically permit onsite burial of an intact reactor vessel at the Wiscasset radioactive waste site, in the back yard of Governor King in Brunswick, Maine, or dumping the reactor vessel overboard in the Gulf of Maine or Cape Cod Bay.
SAMPLE: (as used in MARSSIM) a part or selection from a medium located in a survey unit or reference area that represents the quality or quantity of a given parameter or nature of the whole area or unit; a portion serving as a specimen. (MARSSIM, pg. GL-15). RADNET note: another controversial MARSSIM definition.
STEAM GENERATOR TUBES: These tubes are part of pressurized water reactors. The following subset of definitions are used by the NRC in Draft Regulatory Guide DG-1074 for inspecting the integrity of these tubes.
WASTE ISOLATION PILOT PLANT: a geologic repository intended to provide permanent deep underground disposal for transuranic waste. If approved, the Waste Isolation Pilot Plant is expected to open in 1998. (BEMR, June 1996, pg. GL-10).
WET/DRY: a reference to characterization of contamination
within a sample of any media during laboratory analysis, especially spectroanalysis.
Specimens being analyzed are either wet weight (ww) or dry weight (dw),
meaning the wet samples have been ashed to remove all water. This results
in dry samples having much more contamination per unit weight than wet
samples: a convenient conversion factor is 8; that is, a dry sample will
generally have 8 times the contamination per kg than a wet sample.
|C. Conversion factors and other useful information|
See RADNET Section 5 for a checklist of biologically significant radionuclides.
TABLE OF PREFIXES:
|Multiply||By||To Obtain||Multiply||By||To Obtain|
|Ci||3.7 x 1010||Bq||Bq||2.7 x 10-11||Ci|
|dpm||0.0167||dps or Bq||dps or Bq||60.0||dpm|
|mCi km-2||37.0||Bq m-2||Bq m-2||0.027||mCi km-2|
|pCi L-1||37.0||mBq L-1||mBq L-1||0.027||pCi L-1|
|fCi m-3||0.037||mBq m-3||mBq m-3||27.027||fCi m-3|
|gray (Gy)||100||rad||rad||0.01||gray (Gy)|
|km||0.621||mile (mi)||mile (mi)||1.61||km|
|m2||3.861 x 10-7||sq. mile (mi2)|
|km2||0.386||sq. mile||sq. mile||2.59||km2|
|liter (L)||0.001||m3||m3||1000||liter (L)|
|liter (L)||33.814023||ounce (fluid)||ounce (fluid)||0.039572702||liter (L)|
|liter (L)||1.057||quart (liquid-US)||quart (liquid-US)||0.946||liter (L)|
to a page at Queen's University at Kingston also gives some radiation measurement
units conversion factors.
(1)This table is adapted from
UNSCEAR (1982), Annex F, Table 37, pg. 312.
|Material||Plutonium||Americium, curium and neptunium|
|Benthic algae and macrophytes||5,000||50,000|
|Piscivorous (fish eaters)||5||50|
(2) Taken from Hanson, W.C. ed. (1980). Transuranic Elements in the Environment. pg. 620
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