Section II - Definitions
I. DEFINITIONS
acceptance testing: Evaluation or measurement of performance
characteristics to verify that certain stated specifications and
contractual requirements are met.
accuracy: The closeness of agreement between the result of a
measurement and the true value of the measurand.
adjust: To alter the response by means of a variable, built-in control,
such as a potentiometer.
as low as reasonably achievable (ALARA): The "approach" to radiation
protection to manage and control exposures (both individual and
collective) to the work force and to the general public to levels as low
as is reasonable, taking into account social, technical, economic,
practical, and public policy considerations. "ALARA is not a dose limit
but a process" which has the objective of attaining doses as far below
the applicable limits of 10 CFR 835 as is reasonably achievable.
bias: A deviation, always of the same magnitude and direction, of
measurement value from the "true value".
calibration: To adjust and/or determine either:
(1) The response or reading of an instrument relative to a
standard (e.g., primary, secondary, or tertiary) or to a
series of conventionally true values; or
(2) The strength of a radiation source relative to a standard
(e.g., primary, secondary, or tertiary) or conventionally true
value.
Also see "instrument calibration" or "source calibration."
calibration points: The distances from a source at which the reference
values for the field intensity (exposure rates) are known or evaluated
for fixed conditions of collimation, attenuation and scatter.
check source: A radioactive source, not necessarily calibrated, used to
confirm an acceptable level of instrument response to radiation exposure.
coefficient of variation (relative error): The standard deviation
expressed as a percentage of the mean (i.e., (standard
deviation/x)(100)).
consistency: Agreement of a measurement's result with the appropriate
standard to within a specified level.
consistency demonstration: Use of a comparative device to directly
obtain measurement results that are demonstrated to be sufficiently in
agreement with the appropriate standard.
control chart: A plot of the results of a quality control action to
record and demonstrate that control is being maintained within expected
statistical variation or to indicate when control is or will be lost
without intervention.
conventionally true value of a quantity: The commonly accepted, best
estimate of the true value of a quantity. The conventionally true value
and the associated uncertainty will normally be determined by comparison
with a national or transfer standard, using a reference instrument that
has been calibrated against a national, or transfer standard.
correction factor: The factor by which the reading of an instrument is
multiplied to obtain the conventionally true value of the quantity.
decade: A range of values for which the upper value is a power of ten
above the lower value.
demonstrated consistency: See "consistency demonstration".
detector: A device or component that produces a measurable response to
ionizing radiation.
energy dependence: A change in instrument response with respect to the
specific energy of the radiation being measured for a constant exposure
rate.
free-space geometry: A calibration geometry in which the radiation
emitted from a bare or collimated source in air reaches the instrument
under calibration with minimal scatter from nearby structures.
functional tests: Tests (often qualitative) to determine that an
instrument is operational and capable of performing its intended
function. Such tests include examination of voltage settings, zero
settings, response to radiation, etc.
geotropism: A change in the instrument's reading, as its orientation
changes, due to gravitational effects.
instrument (radiation detection): A complete system consisting of one
or more subassemblies (e.g., detector, readout, etc.) designed to
quantify, when exposed to radiation, one or more characteristics of
ionizing radiation or radioactive material.
instrument calibration: (1) Adjustment of the response of a given
instrument to agree with the response of a standard instrument when both
are used to measure the same quantity under the same conditions; or (2)
determination of the response of a given instrument when measuring a
physical standard under well-defined conditions.
laboratory, secondary: A laboratory that maintains and uses a secondary
standard as its reference standard.
laboratory, tertiary: A laboratory that maintains and uses a tertiary
standard as its reference standard.
overload response: The behavior of an instrument when exposed to
radiation intensities greater than the upper measurement limit.
portable survey instrument: An instrument intended to be operated while
being carried by an individual.
precision: The degree of agreement of repeated measurements of the same
parameter.
proficiency test: A test of laboratory performance by intercomparison
of results obtained from calibration of a common instrument or radiation
source by both the laboratory under evaluation and a reference
laboratory.
quality assurance program: A program for achieving and verifying
quality.
quality control: Quality assurance actions that achieve and sustain
attributes of the material, process, component, system, or facility in
accordance with predetermined requirements.
range: All values between the lower detection limit and the upper
measurement limit.
reading: The indicated value of the readout.
readout: The device that conveys visual information regarding the
measurement results to the user.
reference field: Radiation fields in which reference values for the
field intensity have been established.
reference point: The geometrical center of the sensitive volume of the
detector which is generally located by a mark (or marks) on the detector
housing or instrument case.
reference value: The value of a particular quantity (e.g., exposure
rate) that characterizes a laboratory's radiation field. It is the
value to which the reading of an instrument under calibration is
compared.
response: The instrument indication produced as a result of some
influence.
scale: A sub-range of the total range of measurement.
sensitivity: For a given value of the measured quantity, the ratio of
the variation of the observed variable to the corresponding variation of
the measured quantity.
shall: Within the context of this Guide the word "shall" is used to
designate requirements from 10 CFR 835, DOE Orders, the RCM, and
secondary documents invoked by them.
should and may: Within the context of this Guide, the words "should" and
"may" are used to represent optional program recommendations and allowable
alternatives, respectively. Deviations generally require no specific
approval or justification; however exceptions or deviations to "should"
provisions referenced directly from the RCM require specific justification
and approval in accordance with Article 113.3 of that manual (i.e., RCM
113.3).
standard (instrument or source):
-- primary (or national) standard: An instrument, source, or other
system or device maintained by the National Institute of Standards
and Technology (NIST) (formerly the U.S. National Bureau of
Standards).
-- secondary standard: An instrument, source, or other system or
device that has been compared directly with a national standard.
Generally reserved for use as a laboratory standard.
-- tertiary standard: An instrument, source, or other system or
device that has been compared directly with a secondary standard.
Generally reserved for use as a laboratory standard.
-- transfer standard: A physical measurement device, typically a
measurement instrument or a radiation source specifically designed
for transport, that has been compared directly or indirectly with a
national standard. This standard may be used as a laboratory
standard.
-- working standard: An instrument, source, or other system or device
calibrated by comparison with a standard other than a National
Standard.
test: A procedure whereby the instrument, component, or circuit is
evaluated against certain criteria for satisfactory operation.
traceability: The ability to show, through documentation, that a
particular instrument or radiation source has either been calibrated
using the national standard or has been calibrated using a transfer
standard in a chain or echelon of calibrations, ultimately leading to a
comparison with the national standard.
type test: A test of one or more production instruments, of the same
design, to verify the actual operational performance characteristics
against the expected or advertised performance specifications.