A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
1. The process of determining whether a practice is, overall, beneficial, as required by ICRP’s System of Radiological Protection, i.e. whether the benefits to individuals and to society from introducing or continuing the practice outweigh the harm (including radiation detriment) resulting from the practice.
2. The process of determining whether a proposed intervention is likely, overall, to be beneficial, as required by ICRP’s System of Radiological Protection, i.e. whether the benefits to individuals and to society (including the reduction in radiation detriment) from introducing or continuing the intervention outweigh the cost of the intervention and any harm or damage caused by the intervention.
The quantity K, defined as:
where dEtr is the sum of the initial kinetic energies of all charged ionizing particles liberated by uncharged ionizing particles in a material of mass dm. 
Unit: gray (Gy).
Originally an acronym for kinetic energy released in matter, but now accepted as a word.
air kerma: The kerma value for air.
Under charged particle equilibrium conditions, the air kerma (in gray) is numerically approximately equal to the absorbed dose in air (in gray).
reference air kerma rate: The kerma rate to air, in air, at a reference distance of one metre, corrected for air attenuation and scattering. 
This quantity is expressed in µGy/h at 1 m.
Any organization, corporation, partnership, firm, association, trust, estate, public or private institution, group, political or administrative entity or other persons designated in accordance with national legislation, who or which has responsibility and authority for any action having implications for protection or safety.
Contrasted in legal texts with natural person, meaning an individual.
action level: The level of dose rate or activity concentration above which remedial actions or protective actions should be carried out in chronic exposure or emergency exposure situations. 
emergency action level (EAL): A specific, predetermined, observable criterion used to detect, recognize and determine the emergency class of an event.
An EAL could represent an instrument reading, the status of a piece of equipment or any observable event, such as a fire. In this sense, it is not strictly an action level as defined above, but has essentially the same function.
clearance level: A value, established by a regulatory body and expressed in terms of activity concentration and/or total activity, at or below which a source of radiation may be released from regulatory control.
See also clearance (1).
exemption level: A value, established by a regulatory body and expressed in terms of activity concentration and/or total activity, at or below which a source of radiation may be granted exemption from regulatory control without further consideration.
In the BSS , the term exemption levels is used, and values are specified in Table I-1 of Schedule I, but neither exemption nor exemption level is defined in the BSS glossary.
guidance level: A level of a specified quantity above which appropriate actions should be considered. In some circumstances, actions may need to be considered when the specified quantity is substantially below the guidance level. 
guidance level for medical exposure: A value of dose, dose rate or activity selected by professional bodies in consultation with the Regulatory Authority to indicate a level above which there should be a review by medical practitioners in order to determine whether or not the value is excessive, taking into account the particular circumstances and applying sound clinical judgement. 
intervention level: The level of avertable dose at which a specific protective action or remedial action is taken in an emergency exposure situation or a chronic exposure situation. 
operational intervention level (OIL): A calculated level, measured by instruments or determined by laboratory analysis, that corresponds to an intervention level or action level.
OILs are typically expressed in terms of dose rates or of activity concentrations of radionuclides in environmental, food or water samples. In this sense, they are not strictly intervention levels as defined above, but have essentially the same function.
investigation level: The value of a quantity such as effective dose, intake, or contamination per unit area or volume at or above which an investigation should be conducted. 
recording level: A level of dose, exposure or intake specified by the Regulatory Authority at or above which values of dose, exposure or intake received by workers are to be entered in their individual exposure records. 
reference level: An action level, intervention level, investigation level or recording level. 
1. A legal document issued by the regulatory body granting authorization to perform specified activities related to a facility or activity.
The holder of a current licence is termed a licensee. Other derivative terms should not be needed; a licence is a product of the authorization process (although the term licensing process is sometimes used), and a practice with a current licence is an authorized practice.
Authorization may take other forms, such as registration.
2. [Any authorization granted by the regulatory body to the applicant to have the responsibility for the siting, design, construction, commissioning, operation or decommissioning of a nuclear installation.] 
3. [Any authorization, permission or certification granted by a regulatory body to carry out any activity related to management of spent fuel or of radioactive waste.] 
! The definitions (2) and (3) from the Conventions are somewhat more general in scope than the normal Agency usage in definition (1). In Agency usage, a licence is a particular type of authorization, normally representing the primary authorization for the operation of a whole facility or activity. The conditions attached to the licence may require that further, more specific, authorization or approval be obtained by the licensee before carrying out particular activities.
See licence (1).
See licence (1).
The value of a quantity used in certain specified activities or circumstances that must not be exceeded. 
! The term limit should only be used for a criterion that must not be exceeded, e.g. where exceeding the limit would cause some form of legal sanction to be invoked. Criteria used for other purposes — e.g. to indicate a need for closer investigation or a review of procedures, or as a threshold for reporting to a regulatory body — should be described using other terms, such as reference level.
acceptable limit: A limit acceptable to the regulatory body.
The term acceptable limit is usually used to refer to a limit on the predicted radiological consequences of an accident (or on potential exposures if they occur) that is acceptable to the relevant regulatory body when the probability of occurrence of the accident or potential exposures has been taken into account (i.e. on the basis that it is unlikely to occur). The term authorized limit should be used to refer to limits on doses or risks, or on releases of radionuclides, which are acceptable to the regulatory body on the assumption that they are likely to occur.
annual limit on intake (ALI): The intake by inhalation, ingestion or through the skin of a given radionuclide in a year by Reference Man which would result in a committed dose equal to the relevant dose limit. 
The ALI is expressed in units of activity.
See ICRP .
authorized limit: A limit on a measurable quantity, established or formally accepted by a regulatory body.
Equivalent in meaning to prescribed limit, authorized limit has been more commonly used in radiation and waste safety, particularly in the context of limits on discharges.
Wherever possible, authorized limit should be used in preference to prescribed limit.
derived limit: A limit on a measurable quantity set, on the basis of a model, such that compliance with the derived limit may be assumed to ensure compliance with a primary limit.
dose limit: The value of the effective dose or the equivalent dose to individuals from controlled practices that shall not be exceeded. 
operational limits and conditions: A set of rules setting forth parameter limits, the functional capability and the performance levels of equipment and personnel approved by the regulatory body for safe operation of an authorized facility.
prescribed limit: A limit established or accepted by the regulatory body.
The term authorized limit is preferred.
primary limit: A limit on the dose or risk to an individual.
safety limits: Limits on operational parameters within which an authorized facility has been shown to be safe.
Safety limits are operational limits and conditions beyond those for normal operation.
secondary limit: A limit on a measurable quantity, which corresponds to a primary limit.
e.g. the annual limit on intake, a secondary limit, corresponds to the primary limit on annual effective dose for a worker.
Such a limit meets the definition of derived limit, and therefore derived limit should be used.
linear energy transfer (LET), LD:
Defined generally as:
where dE is the energy lost in traversing distance dl and D is an upper bound on the energy transferred in any single collision.
A measure of how, as a function of distance, energy is transferred from radiation to the exposed matter. A high value of LET indicates that energy is deposited within a small distance.
LY (i.e. with D = Y) is termed the unrestricted linear energy transfer, in defining quality factor.
LD is also known as the restricted linear collision stopping power.
The generation of a required binary output signal from a number of binary input signals according to predetermined rules, or the equipment used for generating this signal.
low dispersible radioactive material:
Either a solid radioactive material or a solid radioactive material in a sealed capsule, that has limited dispersibility and is not in powder form. 
A slightly less restrictive category than special form radioactive material.
low toxicity alpha emitters:
Natural uranium; depleted uranium; natural thorium; uranium-235 or uranium-238; thorium-232; thorium-228 and thorium-230 when contained in ores or physical and chemical concentrates; or alpha emitters with a half-life of less than 10 days.