V
Volumetric flow rate (in mL s-1) of inspired air.
(ICRP 66)
VD (BB)
Anatomical dead space (in L) of the trachea and bronchi.
(ICRP 66)
VD (bb)
Anatomical dead space of the bronchioles (L).
(ICRP 66)
Vm
Component of the total volumetric flow rate (in mL s-1) that is inspired through the mouth.
(ICRP 66)
Vn
Component of the total volumetric flow rate (in mL s-1) that is inspired through the nose.
(ICRP 66)
VT
Tidal volume (in L) of exposed subject.
(ICRP 66)
Vadose zone
The unsaturated region of subsurface soil where the interstitial pores between the soil particles are only partially filled with water.
(10CFR834.2)
Valence
Number representing the combining or displacing power of an atom; number of electrons lost, gained or shared by an atom in a compound; number of hydrogen atoms with which an atom will combine, or which it will displace.
(RHH)
Validation
Defining the process of the method capability and determining whether it can be properly applied as intended (ASTM 1995b).
(HPS N13.30-1996)
Value (isotope separation)
A measure of the difficulty of preparing a given quantity of one isotopic composition from a given quantity of another isotopic composition.
(ANSI N1.1-1976)
Valve (air or oxygen)
A device which controls the pressure, direction, or rate of flow of air or oxygen.
(ANSI Z88.2-1980)
Valve (air or oxygen)
A device which controls the direction of air or oxygen flow or the rate and pressure at which air or oxygen is delivered, or both.
(ANSI Z88.2-1969)
Van de Graff accelerator
An electrostatic machine in which electrical charge is carried into the high voltage terminal by a belt made of an insulating material moving at high speed. The particles are then accelerated along a discharge path through a vacuum tube by the potential difference between the insulated terminal and the grounded end of the accelerator.
(RHH)
Van de Graff generator (accelerator)
An electrostatic machine in which electrically charged particles are sprayed on a moving belt and carried by it to build up a high potential on an insulated terminal. Charged particles are then accelerated along a discharge path through a vacuum tube by the potential difference between the insulated terminal and the opposite end of the machine. A Van de Graaff accelerator is often used to inject particles into larger accelerators. Named after R.S. Van de Graaff, who invented the device in 1931. (See accelerator.)
(USAEC-1974)
Vapor
The gaseous state of a substance that is solid or liquid at ordinary temperature and pressure.
(ANSI Z88.2-1980)
Vapor
The gaseous form of materials which are liquids or solids at room temperature, as distinguished from non-condensable gases. (Vapors are gases but carry the connotation of having been released or volatilized from liquids or solids.)
(ANSI N13.1-1969)
Vapor
The gaseous state of a substance that is solid or liquid at ordinary temperature and pressure.
(ANSI Z88.2-1969)
Vapor pressure
Partial pressure of a liquid's vapor required to maintain the vapor in equilibrium with the condensed liquid or solid; also referred to as saturation vapor pressure.
(AM-1993)
Vapor suppression
A safety system that can be incorporated in the design of structures housing water reactors. In the system, the space surrounding the reactor is vented into pools of water open to the outside air. If surges of hot vapors should be released from the reactor in an accident, their energy (pressure) would be dissipated in the pools of water. Gases not condensed would be scrubbed clean of radioactive particles by the bubbling. Another system uses a suppression pool in a separate pressure vessel that can be vented through a stack. Also called pressure suppression.
(USAEC-1974)
Vapors
The gaseous form of substances which are normally in the solid or liquid state and which can be changed to these states either by increasing the pressure or decreasing the temperature alone. Vapors diffuse.
(ANSI Z9.2-1971)
Variability
Measure of spread of repeated measurements of a parameter.
(AM-1993)
Variable
A quantity or condition that is subject to change or a quantity that can assume any of a given set of values.
(ANSI/ANS-3.8.1-1987)
Variance
Square of the standard deviation; a measure of variability.
(AM-1993)
Vault
A windowless enclosure with walls, floor, roof and door(s) designed and constructed to delay penetration from forced entry.
(10CFR74.4)
Vault
A windowless enclosure with walls, floor, roof and door(s) designed and constructed to delay penetration from forced entry.
(10CFR73.2)
Vault-type room
A room with one or more doors, all capable of being locked, protected by an intrusion alarm which creates an alarm upon the entry of a person anywhere into the room and upon exit from the room or upon movement of an individual within the room.
(10CFR73.2)
Vena contracta
Flow contraction with flow separation from the wall, usually occurring after constriction of a flow channel or just downstream of the entry point of an inlet.
(AM-1993)
Ventilation
The act of admitting fresh air into a space in order to replace stale or contaminated air, achieved by blowing air into the space. Ventilation can be achieved both naturally and mechanically.
(RRM)
Ventilation exhaust
The air and gas discharge from building spaces including: air supplied to the building for cooling and life support; air supplied to cells for cooling and purging hazardous materials; and gases that leak into building spaces from process equipment. After adequate treatment, offgas-system effluent may be combined with ventilation exhaust or may be discharged separately.
(ANSI N303-1978)
Ventilation rate
See minute volume.
(NCRP 76)
Ventricular zone
The ventricular zone contains only ventricular cells; the latter are simply mitotic and intermitotic forms of a single pseudostratified columnar epithelial cell. The ventricular cells are the ultimate progenitors of all neurons and macroglial cells of the central nervous system, and the zone itself becomes attenuated and eventually disappears as its cells become transformed.
(ICRP 49)
Venturi meter
A device used to measure flow rate in a duct by measuring the pressure drop across a calibrated streamlined constriction.
(AM-1993)
Verification
An act of confirming, substantiating, or assuring that an action, condition, or goal has been implemented, completed, or accomplished according to the specified requirements.
(HPS N13.30-1996)
Verification
An act of confirming, sustaining, or assuring that an action, condition, or goals has been implemented, completed, or accomplished according to the specified requirements.
(ANSI N13.30-1989D)
Verification
The establishing of the validity of data or documentation.
(ANSI N15.37-1981)
Verification
The act of reviewing, inspecting, testing checking, auditing, or otherwise determining and documenting whether items, processes, services, or documents conform to specified requirements.
(ANSI N46.2-1978)
Vertical elutriator
A vertical channel that gravitationally retains or removes particles above a given size or size range and emits the remaining airborne particles.
(AM-1993)
Very high radiation area
An area accessible to individuals, in which radiation levels could result in an individual receiving and absorbed dose in excess of 500 rads (5 grays) in 1 hour at 1 meter from a radiation source or from any surface that the radiation penetrates.
(10CFR20.1003)
Very high radiation area
Any area accessible to individuals in which radiation levels could result in an individual receiving an absorbed dose in excess of 500 rads (5 grays) in one hour at 1 meter from a radiation source or from any surface that the radiation penetrates.
(10CFR835.2-1993)
Vessel design pressure
A pressure at least 10% higher than the maximum difference in pressure between the inside and outside of the containment vessel which exists under the most severe loadings, as specified by the cask designer.
(ANSI N14.19-1986)
Vial
A glass or plastic sample container which meets the dimensional specifications of the International Electrotechnical Commission IEC 582-77.
(ANSI N42.15-1980)
Virtual impactor
A device in which particles are removed by impacting them through a virtual surface into a stagnant volume, or a volume with a slowly moving airflow, so that large particles remain in this volume while smaller particles are deflected with the bulk of the original air flow; the dichotomous impactor is a frequently used virtual impactor.
(AM-1993)
Virus
A microorganism that needs a complete cell to reproduce.
(AM-1993)
Visitor
A member of the general public. Visitors are individuals who do not work at a facility; however, radiation records are maintained for visitors who are monitored for the purpose of compliance with the radiation protection program.
(NCRP 114)
Vital area
Any area which contains vital equipment.
(10CFR73.2)
Vital Capacity
Maximum amount of air breathed in during inspiration.
(NCRP 125)
Vital capacity
Maximum volume of gas that can h exhaled from the lung after maximum inhalation.
(AM-1993)
Vital equipment
Any equipment, system, device, or material, the failure, destruction, or release of which could directly or indirectly endanger the public health and safety by exposure to radiation. Equipment or systems which would be required to function to protect public health and safety following such failure, destruction, or release are also considered to be vital.
(10CFR73.2)
Vitreous
The semifluid, transparent substance which lies between the retina and the lens of the eye.
(NCRP 98)
Void coefficient
The partial derivative of reactivity with respect to a void (i.e., the removal of the material) at a specified location within a reactor. It is equal to the reactivity coefficient of the material removed.
(ANSI N1.1-1976)
Void coefficient
A rate of change in the reactivity of a water reactor system resulting from a formation of steam bubbles as the power level and temperature increase.
(USAEC-1974)
Volatile
Having a high vapor pressure at room temperature.
(ANSI N13.1-1969)
Volt
The unit of electromotive force (1 V = 1 W/1 A).
(RHH)
Voltage, operating
As applied to radiation detection instruments, the voltage across the electrodes in the detecting chamber required for proper detection of the ionizing event.
(RHH)
Voltage, starting
For a counter tube, the minimum voltage that must be applied to obtain counts with the particular circuit with which it is associated.
(RHH)
Volume activity, activity concentration
Activity per unit volume.
(IEC 50-393-1993)
Volume ion density
Number of ion pairs per unit volume.
(IEC 50-393-1993)
Volume, sensitive
The portion of a counter tube or ionization chamber which responds to a particular radiation.
(RHH)
Volume-seeking radionuclide
See surface-seeking radionuclide.
(FGR 11)
Voxel
A volume element in the object being imaged. The mean attenuation coefficient of the voxel determines the CT (Hounsfield) number of the pixel.
(NCRP 102)
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