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

E

effective dose:
See dose quantities.

emergency action:
An action performed to mitigate the impact of an emergency on human health and safety, property or the environment.

emergency action level (EAL)::
See action level.

emergency arrangements:
The set of tools, materials, plans, procedures, agreements and protocols needed to perform emergency actions.

emergency class:
A set of events that warrant similar immediate emergency response.
Used for communicating to the response organizations and the public the level of response needed. The events that belong to a given emergency class are defined by installation-, source- or practice-specific criteria, which if exceeded trigger classification at the prescribed level.  For each emergency class, the initial actions of the response organizations are predefined.
The Agency defines three emergency classes, namely (in order of increasing severity) alert, site area emergency and general emergency.

emergency classification:
The process whereby an authorized official decides to which emergency class an event belongs, and declares that the relevant level of emergency exists.
Upon declaration of the emergency class, the response organizations initiate the predefined response actions for that emergency class.

emergency plan:
1.   A document describing the organizational structures, roles and responsibilities, concept of operation, means and principles for intervention during an emergency.
Emergency plans are prepared at several different levels: national, local and facility.  They may include all activities planned to be carried out by all relevant organizations and authorities, or may be primarily concerned with the actions to be carried out by a particular organization.  The term overall emergency plan is sometimes used for clarification when the former meaning is intended.
Details regarding the accomplishment of specific tasks outlined in an emergency plan are contained in emergency procedures.
2.   A set of procedures to be implemented in the event of an accident. [40]

emergency planning:
The process of developing and maintaining the capability to take actions that will mitigate the impact of an emergency on human health and safety, property or the environment.

emergency preparedness:
The capability to promptly take actions that will effectively mitigate the impact of an emergency on human health and safety, property or the environment.

emergency procedures:
A set of documents describing the detailed actions to be taken by response personnel during an emergency.

emergency response:
The performance of actions to mitigate the impact of an emergency on human health and safety, quality of life, property or the environment.

employer:
A legal person with recognized responsibility, commitment and duties towards a worker in his or her employment by virtue of a mutually agreed relationship. [40]

! A self-employed person is regarded as being both an employer and a worker.

endpoint:
1.   The final stage of a process, especially the point at which an effect is observed.
Used, somewhat loosely, to describe a range of different results or consequences.  For example, the term ‘biological endpoint’ is used to describe a health effect (or a probability of that health effect) that could result from exposure.
2.   A radiological or other measure of protection or safety that is the calculated result of an analysis or assessment.
Common endpoints include estimates of dose or risk, estimated frequency or probability of an event or type of event (such as core damage), expected number of health effects in a population, predicted environmental concentrations of radionuclides, etc.
3.   A predetermined criterion defining the point at which a specific task or process will be considered completed.
This usage often occurs in contexts such as decontamination or cleanup, where the endpoint is typically the level of contamination beyond which further decontamination or cleanup is considered unnecessary.  (In such a context, this criterion may also be an endpoint in the sense of definition (2) — such criteria are often calculated on the basis of a level of dose or risk that is considered acceptable — but its application to the actual decontamination or cleanup operations is in the sense of definition (3))

enforcement:
The application by a regulatory body of sanctions against an operator intended to correct and, as appropriate, penalize non-compliance with conditions of an authorization.

environmental monitoring:
See monitoring (1).

equipment qualification:
See qualification.

equivalent dose:
See dose quantities.

evacuation:
The rapid, temporary removal of people from an area to avoid or reduce short term radiation exposure in an emergency situation.
Evacuation is an urgent protective action (a form of intervention).  If people are removed from the area for a longer period of time (more than a few months), the term relocation is used.
Evacuation may be performed as a precautionary action based on plant conditions within the precautionary action zone.

event:
In the context of the reporting and analysis of events, an event is any unintended occurrence, including operating error, equipment failure or other mishap, the consequences or potential consequences of which are not negligible from the point of view of protection or safety.

! As with INES, the terminology related to the reporting and analysis of events is not always consistent with the terminology used in safety standards, and great care should be taken to avoid confusion.  In particular, the definition of event given above is identical in essence to the safety standards definition (1) of accident.  This difference derives from the fact that event reporting and analysis is concerned directly with the question of whether an event that could develop into an accident with significant consequences actually does so; terms such as accident are used only to describe the end result and therefore other terms are needed to describe the earlier stages.

exclusion:
The deliberate exclusion of a particular category of exposure from the scope of an instrument of regulatory control on the grounds that it is not considered amenable to control through the regulatory instrument in question.  Such exposure is termed excluded exposure.
This term is most commonly applied to those exposures from natural sources that are least amenable to control, such as cosmic radiation at sea level or potassium-40 in the human body.
The concept is related to those of clearance (which is normally used in relation to materials) and exemption (which relates to practices or sources).

exemption:
The determination by a regulatory body that a source or practice need not be subject to some or all aspects of regulatory control on the basis that the exposure (including potential exposure) due to the source or practice is too small to warrant the application of those aspects.
Some references (e.g. ICRP 60 [48]) extend the scope of exemption to include any sources and practices for which exemption is the optimum protection option, i.e. where the reduction in doses or risks that could be achieved through regulatory control are disproportionately small in relation to the costs associated with such regulatory control (irrespective of the actual level of the doses or risks).  The preferred Agency usage is restricted to the cases where the doses and risks are very low.
See also clearance (1) and exclusion.

exposure:
1.   The act or condition of being subject to irradiation.
The term is also used in a more general sense to describe the act or condition of being in contact with certain radioactive materials, particularly radon or other airborne radionuclides (resulting in exposure to the radiation emitted by those radionuclides).  Care should be taken if the term is used in this way.

! Exposure should not be used as a synonym for dose.  Dose is a measure of the degree of exposure.

Exposure can be divided into categories according to its nature and duration (see exposure situations) or according to the source of the exposure, the people exposed and/or the circumstances under which they are exposed (see exposure, types of).

2.   The sum of the electrical charges of all of the ions of one sign produced in air by X rays or gamma radiation when all electrons liberated by photons in a suitably small element of volume of air are completely stopped in air, divided by the mass of the air in the volume element.
Unit: C/kg (in the past, the roentgen (R) was used).

exposure, types of:

exposure pathway:
A route by which radiation or radionuclides can reach humans and cause exposure.
An exposure pathway may be very simple, e.g. external exposure from airborne radionuclides, or a more complex chain, e.g. internal exposure from drinking milk from cows that ate grass contaminated with deposited radionuclides.

exposure situations:

  • acute exposure: Exposure received within a short period of time.
    Normally used to refer to exposure of sufficiently short duration that the resulting doses can be treated as instantaneous (e.g. less than an hour).
    Usually contrasted with chronic exposure and transitory exposure.
  • chronic exposure: Exposure persisting in time. [40]
    Normally used to refer to exposures persisting for many years as a result of long lived radionuclides in the environment.  Exposure that is too protracted to be described as acute exposure, but does not persist for many years, is sometimes described as transitory exposure.<
    ICRP uses the term prolonged exposure to describe the same concept.  Both terms are contrasted with acute exposure (and transitory exposure).

! The adjective ‘chronic’ relates only to the duration of exposure, and does not imply anything about the magnitude of the doses involved.

external event:
Events unconnected with the operation of a facility or activity which could have an effect on the safety of the facility or activity.
Typical examples for nuclear facilities include earthquakes, tornadoes, tsunamis, aircraft crashes, etc.