GLOSSARY
A-D
91b material: Any special nuclear material identified under Section 91b of the Atomic Energy Act of 1954 (42 U.S.C. Section 2121), as amended, exempted from NRC regulation.
Amin: The smallest area of elevated activity identified using the DQO Process that is important to identify.
action level: The numerical value that will cause the decision maker to choose one of the alternative actions. It may be a regulatory threshold standard (e.g., Maximum Contaminant Level for drinking water), a dose- or risk-based concentration level (e.g., DCGL), or a reference-based standard. See investigation level.
activity: See radioactivity.
ALARA (acronym for As Low As Reasonably Achievable): A basic concept of radiation protection which pecifies that exposure to ionizing radiation and releases of radioactive materials should be managed to reduce collective doses as far below regulatory limits as is reasonably achievable considering economic, technological, and societal factors, among others. Reducing exposure at a site to ALARA strikes a balance between what is possible through additional planning and management, remediation, and the use of additional resources to achieve a lower collective dose level. A determination of ALARA is a site-specific analysis that is open to interpretation, because it depends on approaches or circumstances that may differ between regulatory agencies. An ALARA recommendation should not be interpreted as a set limit or level.
alpha (a): The specified maximum probability of a Type I error. In other words, the maximum probability of rejecting the null hypothesis when it is true. Alpha is also referred to as the size of the test. Alpha reflects the amount of evidence the decision maker would like to see before abandoning the null hypothesis.
alpha particle: A positively charged particle emitted by some radioactive materials undergoing radioactive decay.
alternative hypothesis (Ha): See hypothesis.
area: A general term referring to any portion of a site, up to and including the entire site.
area of elevated activity: An area over which residual radioactivity exceeds a specified value DCGLEMC Glossary
area factor (Am): A factor used to adjust DCGLW to estimate DCGLEMC and the minimum detectable concentration for scanning surveys in Class 1 survey units - DCGLEMC = DCGLW · AM. AM is the magnitude by which the residual radioactivity in a small area of elevated activity can exceed the DCGLW while maintaining compliance with the release criterion. Examples of area factors are provided in Chapter 5 of this manual.
arithmetic mean: The average value obtained when the sum of individual values is divided by the number of values.
arithmetic standard deviation: A statistic used to quantify the variability of a set of data. It is calculated in the following manner: 1) subtracting the arithmetic mean from each data value individually, 2) squaring the differences, 3) summing the squares of the differences, 4) dividing the sum of the squared differences by the total number of data values less one, and 5) taking the square root of the quotient. The calculation process produces the Root Mean Square Deviation (RMSD).
assessment: The evaluation process used to measure the performance or effectiveness of a system and its elements. As used in MARSSIM, assessment is an all-inclusive term used to denote any of the following: audit, performance evaluation, management systems review, peer review, inspection, or surveillance.
attainment objectives: Objectives that specify the design and scope of the sampling study including the radionuclides to be tested, the cleanup standards to be attained, the measure or parameter to be compared to the cleanup standard, and the Type I and Type II error rates for the selected statistical tests.
audit (quality): A systematic and independent examination to determine whether quality activities and related results comply with planned arrangements and whether these arrangements are implemented effectively and are suitable to achieve objectives.
background reference area: See reference area.
background radiation: Radiation from cosmic sources, naturally occurring radioactive material, including radon (except as a decay product of source or special nuclear material), and global fallout as it exists in the environment from the testing of nuclear explosive devices or from nuclear accidents like Chernobyl which contribute to background radiation and are not under the control of the cognizant organization. Background radiation does not include radiation from source, byproduct, or special nuclear materials regulated by the cognizant Federal or State agency. Different definitions may exist for this term. The definition provided in regulations or regulatory program being used for a site release should always be used if it differs from the definition provided here.
Becquerel (Bq): The International System (SI) unit of activity equal to one nuclear transformation (disintegration) per second. 1 Bq = 2.7x10-11 Curies (Ci) = 27.03 picocuries (pCi).
beta (b): The probability of a Type II error, i.e., the probability of accepting the null hypothesis when it is false. The complement of beta (1-b) is referred to as the power of the test.
beta particle: An electron emitted from the nucleus during radioactive decay.
bias: The systematic or persistent distortion of a measurement process which causes errors in one direction (i.e., the expected sample measurement is different from the sample's true value).
biased sample or measurement: See judgement measurement.
byproduct material: Any radioactive material (except special nuclear material) yielded in or made radioactive by exposure to the radiation incident to the process of producing or utilizing special nuclear material.
calibration: Comparison of a measurement standard, instrument, or item with a standard or instrument of higher accuracy to detect and quantify inaccuracies and to report or eliminate those inaccuracies by adjustments.
CDE (committed dose equivalent): The dose equivalent calculated to be received by a tissue or organ over a 50-year period after the intake into the body. It dose not include contributions from radiation sources external to the body. CDE is expressed in units of Sv or rem.
CEDE (committed effective dose equivalent): The sum of the committed dose equivalent to various tissues in the body, each multiplied by the appropriate weighting factor (Wt ). CEDE is expressed in units of Sv or rem. See TEDE.
chain of custody: An unbroken trail of accountability that ensures the physical security of samples, data, and records.
characterization survey: A type of survey that includes facility or site sampling, monitoring, and analysis activities to determine the extent and nature of contamination. Characterization surveys provide the basis for acquiring necessary technical information to develop, analyze, and select appropriate cleanup techniques.
Class 1 area: An area that is projected to require a Class 1 final status survey.
Class 1 survey: A type of final status survey that applies to areas with the highest potential for contamination, and meet the following criteria: (1) impacted; (2) potential for delivering a dose above the release criterion; (3) potential for small areas of elevated activity; and (4) insufficient evidence to support reclassification as Class 2 or Class 3.
Class 2 area: An area that is projected to require a Class 2 final status survey.
Class 2 survey: A type of final status survey that applies to areas that meet the following criteria: (1) impacted; (2) low potential for delivering a dose above the release criterion; and (3) little or no potential for small areas of elevated activity.
Class 3 area: An area that is projected to require a Class 3 final status survey.
Class 3 survey: A type of final status survey that applies to areas that meet the following criteria: (1) impacted; (2) little or no potential for delivering a dose above the release criterion; and (3) little or no potential for small areas of elevated activity.
classification: The act or result of separating areas or survey units into one of three designated classes: Class 1 area, Class 2 area, or Class 3 area.
cleanup: Actions taken to deal with a release or threatened release of hazardous substances that could affect public health or the environment. The term is often used broadly to describe various Superfund response actions or phases of remedial responses, such as remedial investigation/feasibility study. Cleanup is sometimes used interchangeably with the terms remedial action, response action, or corrective action.
cleanup standard: A numerical limit set by a regulatory agency as a requirement for releasing a site after cleanup. See release criterion.
cleanup (survey) unit: A geographical area of specified size and shape defined for the purpose of survey design and compliance testing.
coefficient of variation: A unitless measure that allows the comparison of dispersion across several sets of data. It is often used in environmental applications because variability (expressed as a standard deviation) is often proportional to the mean. See relative standard deviation.
comparability: A measure of the confidence with which one data set can be compared to another.
completeness: A measure of the amount of valid data obtained from a measurement system compared to the amount that was expected to be obtained under correct, normal conditions.
composite sample: A sample formed by collecting several samples and combining them (or selected portions of them) into a new sample which is then thoroughly mixed.
conceptual site model: A description of a site and its environs and presentation of hypotheses regarding the contaminants present, their routes of migration, and their potential impact on
sensitive receptors.
confidence interval: A range of values for which there is a specified probability (e.g., 80%, 90%, 95%) that this set contains the true value of an estimated parameter.
confirmatory survey: A type of survey that includes limited independent (third-party) measurements, sampling, and analyses to verify the findings of a final status survey.
consensus standard: A standard established by a group representing a cross section of a particular industry or trade, or a part thereof.
contamination: The presence of residual radioactivity in excess of levels which are acceptable for release of a site or facility for unrestricted use.
control chart: A graphic representation of a process, showing plotted values of some statistic gathered from that characteristic, and one or two control limits. It has two basic uses: 1) as a judgement to determine if a process was in control, and 2) as an aid in achieving and maintaining
statistical control.
core sample: A soil sample taken by core drilling.
corrective action: An action taken to eliminate the causes of an existing nonconformance, deficiency, or other undesirable situation in order to prevent recurrence.
criterion: See release criterion.
critical group: The group of individuals reasonably expected to receive the greatest exposure to residual radioactivity for any applicable set of circumstances.
critical level (Lc): A fixed value of the test statistic corresponding to a given probability level, as determined from the sampling distribution of the test statistic. L c is the level at which there is a statistical probability (with a predetermined confidence) of correctly identifying a background value as "greater than background."
critical value: The value of a statistic (t) corresponding to a given significance level as determined from its sampling distribution; e.g., if Pr ( t > t o) = 0.05, to is the critical value of t at the 5 percent level.
curie (Ci): The customary unit of radioactivity. One curie (Ci) is equal to 37 billion disintegrations per second (3.7 x 1010 dps = 3.7 x 1010 Bq), which is approximately equal to the decay rate of one gram of 226Ra. Fractions of a curie, e.g. picocurie (pCi) or 10-12 Ci and microcurie (µCi) or 10-6 Ci, are levels typically encountered in decommissioning.
cyclotron: A device used to impart high energy to charged particles, of atomic weight one or greater, which can be used to initiate nuclear transformations upon collision with a suitable target.
D: The true, but unknown, value of the difference between the mean concentration of residual radioactivity in the survey unit and the reference area.
DQA (Data Quality Assessment): The scientific and statistical evaluation of data to determine if the data are of the right type, quality, and quantity to support their intended use.
DQOs (Data Quality Objectives): Qualitative and quantitative statements derived from the DQO process that clarify study technical and quality objectives, define the appropriate type of data, and specify tolerable levels of potential decision errors that will be used as the basis for establishing the quality and quantity of data needed to support decisions.
Data Quality Objectives Process: A systematic strategic planning tool based on the scientific method that identifies and defines the type, quality, and quantity of data needed to satisfy a specified use. The key elements of the process include:
· concisely defining the problem
· identifying the decision to be made
· identifying the inputs to that decision
· defining the boundaries of the study
· developing the decision rule
· specifying tolerate limits on potential decision errors
· selecting the most resource efficient data collection design
DQOs are the qualitative and quantitative outputs from the DQO process. The DQO process was
developed originally by the U.S. Environmental Protection Agency, but has been adapted for use
by other organizations to meet their specific planning requirement. See also graded approach.
data quality indicators: Measurable attributes of the attainment of the necessary quality for a particular decision. Data quality indicators include precision, bias, completeness, representativeness, reproducibility, comparability, and statistical confidence.
data usability: The process of ensuring or determining whether the quality of the data produced meets the intended use of the data.
DCGL (derived concentration guideline level): A derived, radionuclide-specific activity concentration within a survey unit corresponding to the release criterion. The DCGL is based on the spatial distribution of the contaminant and hence is derived differently for the nonparametric statistical test (DCGL W) and the Elevated Measurement Comparison (DCGL EMC). DCGLs are derived from activity/dose relationships through various exposure pathway scenarios.
decay: See radioactive decay.
decision maker: The person, team, board, or committee responsible for the final decision regarding disposition of the survey unit.
decision rule: A statement that describes a logical basis for choosing among alternative actions.
decommission: To remove a facility or site safely from service and reduce residual radioactivity to a level that permits release of the property and termination of the license and other authorization for site operation.
decommissioning: The process of removing a facility or site from operation, followed by decontamination, and license termination (or termination of authorization for operation) if appropriate. The objective of decommissioning is to reduce the residual radioactivity in structures, materials, soils, groundwater, and other media at the site so that the concentration of each radionuclide contaminant that contributes to residual radioactivity is indistinguishable from the background radiation concentration for that radionuclide.
decontamination: The removal of radiological contaminants from, or their neutralization on, a person, object or area to within levels established by governing regulatory agencies. Decontamination is sometimes used interchangeably with remediation, remedial action, and cleanup.
delta (d): The amount that the distribution of measurements for a survey unit is shifted to the right of the distribution of measurements of the reference area.
delta ()): The width of the gray region. ) divided by s, the arithmetic standard deviation of the measurements, is the relative shift expressed in multiples of standard deviations. See relative shift, gray region.
derived concentration guideline level: See DCGL.
design specification process: The process of determining the sampling and analysis procedures that are needed to demonstrate that the attainment objectives are achieved.
detection limit: The net response level that can be expected to be seen with a detector with a fixed level of certainty.
detection sensitivity: The minimum level of ability to identify the presence of radiation or radioactivity.
direct measurement: Radioactivity measurement obtained by placing the detector near the surface or media being surveyed. An indication of the resulting radioactivity level is read out directly.
distribution coefficient (Kd): The ratio of elemental (i.e., radionuclide) concentration in soil to that in water in a soil-water system at equilibrium. Kd is generally measured in terms of gram weights of soil and volumes of water (g/cm3 or g/ml).
dose commitment: The dose that an organ or tissue would receive during a specified period of time (e.g., 50 or 70 years) as a result of intake (as by ingestion or inhalation) of one or more radionuclides from a given release.
dose equivalent (dose): A quantity that expresses all radiations on a common scale for calculating the effective absorbed dose. This quantity is the product of absorbed dose (rads) multiplied by a quality factor and any other modifying factors. Dose is measured in Sv or rem.
double-blind measurement: Measurements that cannot be distinguished from routine measurements by the individual performing the measurement. See non-blind measurement and single-blind measurement.
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