REGDOC-3.6, Glossary of CNSC Terminology - Glossary - E


E (E)

See effective dose.

EA (EE)

See environmental assessment.

EA report (rapport d’EE)

See environmental assessment (EA) report under the NSCA or environmental assessment (EA) report under CEAA 2012.

ECCS (SRUC)

See emergency core cooling system.

effective dose (E) (dose efficace[E])

The sum of the products, in sievert, obtained by multiplying the equivalent dose of radiation received by and committed to each organ or tissue set out in column 1 of an item of Schedule 1 by the weighting factor set out in column 2 of that item. (Source: Radiation Protection Regulations)

Note 1: Effective dose is a measure of the total detriment, or risk, due to an exposure to ionizing radiation. If the exposure to different organs or tissues is not uniform (as is the case when radionuclides are deposited in the body), the concept of effective dose is used. The basic idea is to express the risk from the exposure to a single organ or tissue in terms of the equivalent risk from an exposure to the whole body. The unit of effective dose is the sievert.

Note 2: Equivalent dose and effective dose are protection quantities used to reflect how radiation exposure can affect overall health of the human body. They specify dose values, which are derived from the body’s absorbed dose, for limiting the occurrence of stochastic health effects below acceptable levels and avoiding tissue reactions. The effective dose is designed to reflect these differences and how exposure can affect overall health of the whole body.

Note 3: The term weighting factor refers to the tissue weighting factor, which takes into account that different organs and tissue have different radiation sensitivities. For example, bone marrow is much more radiosensitive than muscle or nerve tissue. Effective dose is the summation of the tissue equivalent doses, each multiplied by the appropriate tissue weighting factor. It is defined by:

E = T w T R w R D T , R

where wT is the tissue weighting factor with ∑wT = 1. The sum is performed over all organs and tissues considered in the definition of E.

Note 4: Use of absorbed dose alone is not valid for estimating risk, as radiation effects depend not only on the absorbed dose but also on a) the type of radiation, b) the distribution of energy absorption in time and space within the human body and c) the radiosensitivity of the exposed tissues or organs.

See also absorbed dose, equivalent dose.

effective full power hour (EFPH) (heure équivalente pleine puissance HEPP])

See equivalent full power hour (EFPH).

effective half‑life (demi‑vie effective)

The time required for a radionuclide deposited in the body to decrease to one‑half of its initial quantity as a result of the combined action of radioactive decay and biological elimination.

effective intervention (défense efficace)

An intervention that is timely and powerful enough to prevent a person or a group of persons, including those equipped with weapons or explosive substances, from committing sabotage or from removing Category I, II or III nuclear material otherwise than in accordance with a licence. (Source: Nuclear Security Regulations)

effective kilogram (Ekg) (kilogramme effectif [kgE])

A unit of measurement used in accounting and reporting of safeguarded nuclear material. The quantity in effective kilograms is obtained by taking:

  • for plutonium, its weight in kilograms
  • for uranium with an enrichment of 0.01 (1%) and above, its weight in kilograms multiplied by the square of its enrichment
  • for uranium with an enrichment below 0.01 (1%) and above 0.005 (0.5%), its weight in kilograms multiplied by 0.0001
  • for depleted uranium with an enrichment of 0.005 (0.5%) or below, and for thorium, its weight in kilograms multiplied by 0.00005
effective multiplication factor (keff) (facteur de multiplication effectif [keff])
  • Physically, the ratio of the total number of neutrons produced during a time interval (excluding neutrons produced by sources whose strengths are not a function of fission rate) to the total number of neutrons lost by absorption and leakage during the same interval.
  • Mathematically (computationally), the eigenvalue number that, when divided into the actual mean number of neutrons emitted per fission in an assembly of materials, would make the calculated result for the nuclear chain reaction of that assembly critical.

Also called effective neutron multiplication factor.

effluent (effluent)

A waterborne release of a hazardous or nuclear substance to the environment.

Note: This definition differs from that in CSA N288.6, Environmental risk assessments at Class I nuclear facilities and uranium mines and mills [5], which defines effluent as “the release of contaminants into the environment (including both air and water) as a result of a licensed activity during normal operations”. See also emission.

EFPD (JEPP)

equivalent full-power day

EFPH (HEPP)

See equivalent full power hour.

EHRS (SEUC)

emergency heat removal system

EIR (RIE)

event initial report

EIS (EIE)

See environmental impact statement.

Ekg (kgE)

See effective kilogram.

electrical interaction (interaction électrique)

A force of repulsion acting between electric charges of like sign (charge), or a force of attraction acting between electric charges of unlike sign (charge).

electron volt (eV) (électronvolt [eV])

A unit of energy employed in radiation physics. An eV is equal to the energy that an electron gains when it passes through a potential difference of 1 volt. 1 eV = 1.6 x 10‑19 joules.

EME (EAU)

emergency mitigating equipment

emergency coordinator (coordonnateur des mesures d’urgence)

A person authorized to direct an overall emergency response.

emergency core cooling system (ECCS) (système de refroidissement d’urgence du cœur [SRUC])

A safety system that transfers heat from a reactor core, following a loss of reactor coolant or certain other accidents that exceed makeup capability.

emergency drill (manœuvre d’urgence)

Supervised instruction intended to test, develop, maintain and practise the skills required in a particular emergency response activity.

emergency exercise (exercice d’urgence)

Simulation of emergency events to test the integrated performance of an emergency response scenario. With respect to nuclear criticality safety, this term means an activity that tests one or more portions of the integrated capability of emergency response plans, equipment and organizations.

emergency management and fire protection SCA (DSR Gestion des urgences et protection-incendie)

A safety and control area (SCA) that covers emergency plans and emergency preparedness programs that exist for emergencies and for non‑routine conditions. This area also includes any results of participation in exercises. This SCA is one of the 14 within the CNSC SCA Framework.

emergency plan (plan d’urgence)

The documented measures required of applicants and licensees under the Class I Nuclear Facilities Regulations and Uranium Mines and Mills Regulations. Accordingly, an emergency plan for a Class I nuclear facility or a uranium mine or mill consists of a proposed or actual program to cope with accidental releases. This program encompasses both emergency preparedness and emergency response measures.

emergency response (intervention d’urgence)

The integrated set of equipment, procedures and personnel necessary for performing a specified function or task required for preventing, mitigating or controlling the effects of an accidental release.

OR

With respect to nuclear criticality safety, actions taken from the time of identification of a suspected, imminent or actual criticality accident until stabilization of the event. These actions include the assumption that an accident has occurred, there has been a response to the emergency, and actions to begin subsequent recovery operations have taken place.

emergency response facility (installation d’intervention d’urgence)

An area or room that can be immediately activated when required during an emergency/incident.

emergency response organization (ERO) (organisation d’intervention d’urgence [OIU])

A group of interrelated responders with predefined roles and responsibilities, who work together to mitigate the consequences of an emergency.

emission (émission)

An airborne release of a hazardous or nuclear substance to the environment. An emission may include point sources, fugitive emissions or area sources. See also effluent.

EMS (SGE)

See environmental management system.

enabling objective (EO) (objectif de base)

A principal learning unit that constitutes a major step towards achieving one or more associated terminal learning objectives. The EO consists of a performance statement, condition statement and a standard.

end state (état final)

With respect to decommissioning, the proposed physical, chemical and radiological condition of a facility at the end of the decommissioning program. Note: Where a decommissioning program is to take place in discrete phases, the interim end‑state objectives for each phase should be defined.

end-use controls (contrôles de l’utilisation ultime)

Controls over items that are not otherwise listed in the Nuclear Non-proliferation Import and Export Control Regulations, when such items may be intended for use in connection with a nuclear weapons program or nuclear explosive device. Also called catch-all controls.

enforcement (application de la loi)

All activities to compel a licensee back into compliance and to deter further non‑compliances with the Nuclear Safety and Control Act (NSCA), the regulations made under the NSCA, and licences, decisions, certificates and orders made by the CNSC.

engineered (nuclear) criticality safety control (contrôle technique de sûreté‑criticité [nucléaire])

Either an active or passive engineered control:

  • active engineered control: a physical device that uses active sensors, electrical components or moving parts to maintain safe process conditions without any required human action
  • passive engineered control: a device that uses only fixed physical design features to maintain safe process conditions without any required human action
enhanced administrative control (contrôle administratif amélioré)

See administrative (nuclear) criticality safety control.

enriched uranium (uranium enrichi)

Uranium having a higher abundance of the fissile isotopes (uranium‑235, uranium‑233 or a combination of both) than natural uranium. Note: In the context of packaging and transport of nuclear substances, enriched uranium means uranium containing a greater mass percentage of uranium‑235 than 0.72 percent.A very small mass percentage of uranium‑234 is present.

environment (environnement)

The components of the Earth:

  • land, water and air, including all layers of the atmosphere
  • all organic and inorganic matter and living organisms
  • the interacting natural systems that include the above components
environmental assessment (EA) report for an EA under CEAA 2012 (rapport d’évaluation environnementale [EE] pour une EE en vertu de la LCEE 2012)

A document summarizing the EA process [under the Canadian Environmental Assessment Act, 2012] that takes into consideration the analysis by the proponent and associated perspectives of expert federal authorities, the public, Aboriginal groups, the province (as appropriate) and the responsible authority. (Source: Practitioners Glossary for the Environmental Assessment of Designated Projects under the Canadian Environmental Assessment Act, 2012 [1]) See also environmental assessment (EA) report for an EA under the NSCA.

environmental assessment (EA) report for an EA under the NSCA (rapport d’évaluation environnementale [EE] pour une EE en vertu de la LSRN)

A report prepared by CNSC staff, for the Commission or a designated officer, which documents the findings of an EA under the Nuclear Safety and Control Act (NSCA). Note: On a case-by-case basis, CNSC staff determine the content and appropriate level of detail of this type of report, based on and commensurate with the scale and complexity of the facility or activity and taking into consideration Indigenous, public and regulatory interest. This type of EA report describes and summarizes the results of environmental monitoring, effluent and emissions monitoring and the risks to the environment and the public. Where available, environmental compliance monitoring data and the results of any sampling and analysis activities of the Independent Environmental Monitoring Program (IEMP) conducted near facilities are also included. In particular, the EA report for an EA under the NSCA covers those elements of the facility or activity that are deemed to be of Indigenous, public or general interest. See also environmental assessment (EA) report for an EA under CEAA 2012.

environmental assessment (EA) under CEAA 2012 (évaluation environnementale [EE] en vertu de la LCEE 2012)

An assessment of the environmental effects of a designated project that is conducted in accordance with [the Canadian Environmental Assessment Act, 2012]. (Source: Canadian Environmental Assessment Act, 2012))

Note: As further described in the Practitioners Glossary for the Environmental Assessment of Designated Projects Under the Canadian Environmental Assessment Act, 2012 [1], “An [environmental assessment (EA) under CEAA 2012] predicts the environmental effects of a designated project, identifies mitigation measures, assesses whether the designated project is likely to cause significant adverse environmental effects taking into account identified mitigation measures, and ensures a follow‑up program is designated to verify the accuracy of the EA of the designated project and effectiveness of any mitigation measures.” Compare to environmental protection review (EPR) under the NSCA.

environmental assessment (EA) under the NSCA (évaluation environnementale [EE] en vertu de la LSRN)

See environmental protection review (EPR) under the NSCA. Compare to environmental assessment (EA) under CEAA 2012.

environmental control (contrôle environnemental)

Environmental management procedures or engineering technology and/or techniques that prevent or minimize the release of nuclear and hazardous substances to the environment.

environmental effects (effets environnementaux)

Any change to the environment, whether adverse or beneficial, wholly or partly resulting from a licensed activity or facility, including:

  1. any change that an activity, substance, equipment, facility or prescribed information may cause in the environment, including any change it may cause to a listed wildlife species, its critical habitat or the residences of individuals of that species, as those terms are defined in subsection 2(1) of the Species at Risk Act
  2. any effect of any change referred to in (a) on:
    • health and socio-economic conditions
    • physical and cultural heritage
    • the current use of lands and resources for traditional purposes by Indigenous peoples
    • any structure, site or thing that is of historical, archaeological, paleontological or architectural significance whether any such change or effect occurs within or outside Canada

OR

With respect to an environmental assessment under the Canadian Environmental Assessment Act, 2012 (CEAA 2012), the environmental effects described in section 5 [of that Act]. (Source: Canadian Environmental Assessment Act, 2012))

Note: Section 5 of CEAA 2012 describes environmental effects as follows:

  1. For the purposes of this Act, the environmental effects that are to be taken into account in relation to an act or thing, a physical activity, a designated project or a project are
    1. a change that may be caused to the following components of the environment that are within the legislative authority of Parliament:
      1. fish and fish habitat as defined in subsection 2(1) of the Fisheries Act,
      2. aquatic species as defined in subsection 2(1) of the Species at Risk Act,
      3. migratory birds as defined in subsection 2(1) of the Migratory Birds Convention Act, 1994, and
      4. any other component of the environment that is set out in Schedule 2;
    2. a change that may be caused to the environment that would occur
      1. on federal lands,
      2. in a province other than the one in which the act or thing is done or where the physical activity, the designated project or the project is being carried out, or
      3. outside Canada; and
    3. with respect to aboriginal peoples, an effect occurring in Canada of any change that may be caused to the environment on
      1. health and socio-economic conditions,
      2. physical and cultural heritage,
      3. the current use of lands and resources for traditional purposes, or
      4. any structure, site or thing that is of historical, archaeological, paleontological or architectural significance.
  2. However, if the carrying out of the physical activity, the designated project or the project requires a federal authority to exercise a power or perform a duty or function conferred on it under any Act of Parliament other than this Act, the following environmental effects are also to be taken into account:
    1. a change, other than those referred to in paragraphs (1)(a) and (b), that may be caused to the environment and that is directly linked or necessarily incidental to a federal authority’s exercise of a power or performance of a duty or function that would permit the carrying out, in whole or in part, of the physical activity, the designated project or the project; and
    2. an effect, other than those referred to in paragraph (1)(c), of any change referred to in paragraph (a) on
      1. health and socio-economic conditions,
      2. physical and cultural heritage, or
      3. any structure, site or thing that is of historical, archaeological, paleontological or architectural significance.
  3. The Governor in Council may, by order, amend Schedule 2 to add or remove a component of the environment.
environmental impact statement (EIS) (étude d’impact environnemental (EIE)

A detailed technical document prepared by the proponent of a designated project to be assessed pursuant to [the Canadian Environmental Assessment Act, 2012]. The environmental impact statement identifies the potential adverse environmental effects of a designated project including cumulative effects, measures to mitigate those effects, and an evaluation of whether the designated project is likely to cause any significant adverse environmental effects. (Source: Practitioners Glossary for the Environmental Assessment of Designated Projects Under the Canadian Environmental Assessment Act, 2012 [1])

environmental management system (EMS) (système de gestion de l’environnement [SGE])

The part of an organization’s management system used to develop and implement its environmental policy and manage its environmental aspects. An EMS consists of policies and procedures forming an integrated set of documented activities to provide a framework for effective environmental protection measures.

environmental protection review (EPR) under the NSCA (examen de la protection de l’environnement [EPE] en vertu de la LSRN)

A science-based environmental technical assessment by CNSC staff as set out in the Nuclear Safety and Control Act (NSCA) for all licence applications with potential environmental interactions in accordance with the CNSC’s mandate under the NSCA to ensure the protection of the environment and the health of persons.

Note: Where there are potential environmental interactions, an EPR under the NSCA is conducted for projects not subject to the Impact Assessment Act or other applicable environmental assessment legislation. An EPR describes the outcome of CNSC staff’s review of licensing and environmental compliance activities conducted under the NSCA. This review serves to assess whether the applicant or licensee will, in carrying on a licensed activity, make adequate provision for the protection of the environment and health of persons. This assessment is commensurate with the scale and complexity of the environmental risks associated with the nuclear facility or activity.

environmental protection SCA (DSR Protection de l’environnement)

A safety and control area (SCA) that covers programs that identify, control and monitor all releases of radioactive and hazardous substances and effects on the environment from facilities or as the result of licensed activities. This SCA is one of the 14 within the CNSC SCA Framework.

environmental review (évaluation environnementale)

See environmental assessment (EA) under CEAA 2012 or environmental protection review (EPR) under the NSCA.

environmental risk assessment (ERA) (évaluation des risques environnementaux [ERE])

A process that identifies, quantifies and characterizes the risk posed by contaminants (nuclear or hazardous substances) and physical stressors in the environment. An ERA is a practice or methodology primarily developed by regulatory agencies to provide scientific input to decision makers. In this way, ERAs commonly serve as a supportive tool providing technical information in a manageable form to a larger EA.

EO

See enabling objective.

EPREV (EPREV)

Emergency Preparedness Review (an IAEA service

EPS (AEU)

emergency power supply

EQ (QE)

environmental qualification

equipment qualification (qualification de l’équipement)

The process for certifying equipment as having satisfied the requirements for operability under conditions relevant to its safety functions. Equipment qualification includes the generation and maintenance of evidence to ensure that equipment will operate on demand, under specified service conditions, to meet system performance requirements.

equivalent dose (HT) (dose équivalente [HT])

The product, in sievert, obtained by multiplying the absorbed dose of radiation of the type set out in column 1 of an item of Schedule 2 by the weighting factor set out in column 2 of that item. (Sources: Radiation Protection Regulations; Packaging and Transport of Nuclear Substances Regulations, 2015)

Note 1: Equivalent dose and effective dose are protection quantities used to reflect how radiation exposure can affect overall health of the human body. They specify dose values, which are derived from the body’s absorbed dose, for limiting the occurrence of stochastic health effects below acceptable levels and avoiding tissue reactions. The equivalent dose (multiplying the radiation type by its radiation weighting factor) is designed to reflect the amount of harm caused, regardless of the type of radiation. Values (expressed in seiverts) of equivalent dose to a specified tissue or organ from any type(s) of radiation can be compared directly.

Note 2: The term weighting factor refers to the radiation weighting factor. The equivalent dose is the radiation-weighted dose in an organ or tissue. This value is based on the mean absorbed dose, DT,R, due to radiation of type R and averaged over the volume of a specific organ or tissue T and is defined by:

H T = R w R D T , R

Note 3: Use of absorbed dose alone is not valid for estimating risk, as radiation effects depend not only on the absorbed dose but also on a) the type of radiation, b) the distribution of energy absorption in time and space within the human body and c) the radiosensitivity of the exposed tissues or organs.

See also absorbed dose, effective dose.

equivalent full power hour (EFPH) (heure équivalente pleine puissance [HEPP])

The period over which a component sees service that equals the amount of full service the component would have experienced if it had been operated continuously over a full hour.

ERA (ERE)

See environmental risk assessment.

ERO (OIU)

See emergency response organization.

ESC (CSU)

emergency support centre

escort (escorte)

An individual (normally a staff member or a nuclear security officer) who is authorized by the Commission and licensee to enter the protected or inner area of a nuclear facility and who has been assigned to accompany persons granted escorted entry to the area by the licensee. The escort is expected to maintain control over the activity of the person(s) under escort at all times.

OR

Any person who accompanies a consignment of nuclear material to provide protection against compromise or attack.

ESWS (SSUAE)

emergency secondary water supply system

eV (eV)

See electron volt.

evaluator (évaluateur)

In an emergency exercise, a person who observes, evaluates and critiques the emergency responders’ actions.

event (événement)

Any unintended occurrence, including operating error, equipment failure or another mishap, or deliberate action on the part of others, the consequences or potential consequences of which may be significant from the point of view of protection or safety.

event category (catégorie d’événement)

A group of events characterized by the same or similar cause and similarity in the governing phenomena.

event review (examen d’événement)

All verification activities related to reviewing, assessing and trending of event reports.

excavation site (site d’excavation)

A place at which uranium is moved by means of underground activities for the purpose of evaluating a potential ore body. (Source: Uranium Mines and Mills Regulations)

excepted package (colis excepté)

A package that is designed in accordance with the applicable requirements of the IAEA Regulations. (Source: Packaging and Transport of Nuclear Substances Regulations, 2015)

excessive radiation dose (dose de rayonnement excessive)

In a nuclear criticality accident, any dose to personnel corresponding to an absorbed dose from neutrons and gamma rays equal to or greater than 0.12 gray in free air.

excited state (état excité)

A state of energy of an electron or nucleus when its energy level is higher than in the ground state.

exclusion zone (zone d’exclusion)

A parcel of land within or surrounding a nuclear facility on which there is no permanent dwelling and over which a licensee has the legal authority to exercise control. (Source: Class I Nuclear Facilities Regulations)

exclusive use (utilisation exclusive)

Has the same meaning as in the IAEA Regulations. (Source: Packaging and Transport of Nuclear Substances Regulations, 2015)

excretion function (m) (fonction d’excrétion [m])

A mathematical expression for the fractional excretion of a radionuclide from the body at any time following intake, generally expressed as becquerels excreted per day, per becquerel taken in.

exempted material (matière exemptée)

With respect to nuclear material accounting, any nuclear material that was initially classified as Group 1A and has been granted a temporary classification to Group 1B. The material remains classified as Group 1B until it is reclassified to Group 1A. Material may be exempted on the basis of non‑nuclear use or by a quantity less than 1 effective kilogram.

exemption quantity (quantité d’exemption)

Any of the following:

  1. in respect of a radioactive nuclear substance set out in column 1 of Schedule 1,
    1. if the radioactive nuclear substance is uniformly distributed in material and not in bulk quantity, the corresponding activity concentration set out in column 2, or
    2. the corresponding activity set out in column 3;
  2. in respect of a radioactive nuclear substance that is not set out in column 1 of Schedule 1,
    1. if the atomic number of the substance is equal to or less than 81,
      1. 10 Bq/g if the radioactive nuclear substance is uniformly distributed in material and not in bulk quantity, or
      2. 10,000 Bq,
    2. if the atomic number of the substance is greater than 81 and the substance, or its short-lived radioactive progeny, does not emit alpha radiation,
      1. 10 Bq/g if the radioactive nuclear substance is uniformly distributed in material and not in bulk quantity, or
      2. 10,000 Bq, or
    3. if the atomic number of the substance is greater than 81 and the substance, or its short-lived radioactive progeny, emits alpha radiation,
      1. 1 Bq/g if the radioactive nuclear substance is uniformly distributed in material and not in bulk quantity, or
      2. 1,000 Bq; or
  3. in respect of more than one radioactive nuclear substance,
    1. if the radioactive nuclear substances are uniformly distributed in material and not in bulk quantity, the quotient obtained by dividing the total activity concentration by the sum of quotients obtained by dividing the activity concentration of each radioactive nuclear substance by its corresponding exemption quantity as referred to in paragraph (a) or (b), or
    2. the quotient obtained by dividing the total activity by the corresponding sum of quotients obtained by dividing the activity of each radioactive nuclear substance by its corresponding exemption quantity as referred to in paragraph (a) or (b).

(Source: Nuclear Substances and Radiation Devices Regulations)

Note: Bq/g means becquerels/gram.

exempt material (matière exemptée)

With respect to the packaging and transport of a nuclear substance, a nuclear substance having an activity concentration that does not exceed the values for an exempt material specified in paragraphs 401 to 406 of the IAEA Regulations.

exercise (exercice)

See emergency exercise.

explosive substance (substance explosive)

Includes:

  1. anything intended to be used to make a substance capable of producing an explosion, a detonation or a pyrotechnic effect;
  2. anything, or any part of any thing, used or intended to be used or adapted to cause, or to aid in causing, an explosion in or with a substance referred to in paragraph (a); and
  3. an incendiary grenade, firebomb, Molotov cocktail or other similar incendiary substance or device and a delaying mechanism or other thing intended for use in connection with such a substance or device.

(Source: Nuclear Security Regulations)

export (exportation)

The transfer of a nuclear substance, prescribed equipment or prescribed information from Canada to a foreign destination.

exposure (exposition)

See irradiation.

exposure container (radiography camera) (projecteur [caméra de gammagraphie])

A shield, in the form of a container, designed to allow the controlled use of gamma radiation and employing a sealed source assembly.

exposure device (appareil d’exposition)

A radiation device that is designed for carrying out gamma radiography, and includes any accessory to the device such as a sealed source assembly, a drive mechanism, a sealed source assembly guide tube and an exposure head. (Sources: Nuclear Substances and Radiation Devices Regulations; Packaging and Transport of Nuclear Substances Regulations, 2015)

exposure device source path (organe de transmission de la source de l’appareil d’exposition)

A hollow tunnel inside an exposure container where the sealed source resides when not in use. Also called S‑tube.

exposure head (tête d’exposition)

A device that locates the sealed source included in the sealed source assembly, in the selected working position, and prevents the sealed source assembly from projecting out of the projection sheath. A beam limiter may also serve as an exposure head. Also called source stop.

exposure hours (heures d’exposition)

The total number of hours of employment of all employees for each member utility for each reporting period. Note: Employees include regular hires and direct contractors / augmented / supplemented staff. Contractors working through a separate company are not counted.

extended loss of AC power event (perte prolongée d’alimentation en CA)

See station blackout.

extended shutdown (arrêt prolongé)

A reactor shutdown lasting longer than planned.

external dosimetry (dosimétrie externe)

See dosimetry types.

external event (événement externe)

An event, unconnected with the operation of a facility or conduct of an activity, that could have an effect on the safety of the facility or activity. Some examples are earthquakes, floods, hurricanes, explosions and airplane crashes.

external hazard (danger externe)

An event of natural or human-induced origin that originates outside a site and whose effects on the facility are considered as potentially hazardous.

external worker (travailleur externe)

A person, employed by a firm or organization other than the licensee, who performs work that is referred to in a licence.

extremities (extrémités)

Each part of the human body that is furthest from the head and torso, and that shares similar sensitivities to ionizing radiation. The extremities are further defined as each part of the anatomy from and including the elbows to the tips of the fingers (the upper extremities) and from and including the knees to the tips of the toes (the lower extremities).

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