Language selection


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

I (I)

The activity, in becquerel, of any radionuclide that is taken into the body, excluding the radon progeny and the activity of other radionuclides accounted for in the determination of E. (Source: Radiation Protection Regulations)

Note: E is the effective dose.


See International Atomic Energy Agency.

IAEA Agreement (Accord avec l’AIEA)

The Agreement between the Government of Canada and the International Atomic Energy Agency for the Application of Safeguards in Connection with the Treaty on the Non‑proliferation of Nuclear Weapons, effective on February 21, 1972; INFCIRC/164; UNTS vol. 814, R. No. 11596. (Sources: General Nuclear Safety and Control Regulations; Class I Nuclear Facilities Regulations)

IAEA inspector (inspecteur de l’AIEA)

See International Atomic Energy Agency inspector.

IAEA Regulations (Règlement de l’AIEA)

The Regulations for the Safe Transport of Radioactive Material, published by the IAEA, as amended from time to time. (Source: Packaging and Transport of Nuclear Substances Regulations, 2015)

I&C (IC)

instrumentation and control


International Civil Aviation Organization


See International Commission on Radiological Protection.


International Commission on Radiation Units and Measurements


See Independent Environmental Monitoring Program.

IFB (piscine de stockage du combustible usé)

irradiated fuel bay; see wet storage bay


See integrated implementation plan.


See investigational level.

immediate evacuation zone (zone d’évacuation immédiate)

With respect to nuclear criticality safety, the area surrounding a potential criticality accident location that must be evacuated without hesitation if a criticality accident alarm signal is activated.

immediate rapid deployment (IRD) (déploiement rapide immédiat [DRI])

With respect to security, the start of an immediate pursuit to make direct contact with an active threat as soon as possible, so as to stop the threat by containment, physical arrest or by use of the appropriate level of force.

impairment (déficience)

With respect to nuclear power plants’ safety-related systems, a failure such that a safety-related system would operate with reduced redundancy or margin of safety, or would fail to meet its design intent. Level 1 impairment describes a system state that is impaired to the extent that it would provide inadequate protection. Level 2 impairment describes a system state that is impaired to the extent that it would provide some, but not complete, protection for a worst‑case process failure. Level 3 impairment describes a system state where the level of redundancy or margin of safety is reduced but the system is still fully capable of meeting its design intent.

import (importation)

The transfer of a nuclear substance, prescribed equipment or prescribed information into Canada from a foreign location.

importer (importateur)

A person authorized under the Nuclear Safety and Control Act to import a nuclear substance, prescribed equipment or prescribed information.

importance measures (mesures d’importance)

With respect to probabilistic safety assessments (PSAs), indices on the importance of an event or group of events, comprising:

  • Fussell‑Vesely importance: for a specific basic event, the fractional contribution to PSA results for all accident sequences containing that basic event
  • risk increase ratio (RIR), also called risk achievement worth (RAW): the factor by which the PSA results would increase if the basic event is assumed to happen with certainty (failure probability = 1.0)
  • risk decrease ratio (RDR), also called risk reduction worth (RRW): the amount of reduction in the PSA results to be gained if the basic event is assumed to be available (failure probability = 0.0)

intensity modulated radiation therapy

incident (incident)

See event.

incipient failure (début de la défaillance)

A condition of a component that, if left unremedied, could ultimately lead to a degraded or unavailable component state.

Independent Environmental Monitoring Program (IEMP) (Programme indépendant de surveillance environnementale (PISE))

A CNSC program that complements CNSC staff reviews and approvals of licensees’ environmental monitoring programs and confirms that the public and environment around CNSC-regulated nuclear facilities are not adversely affected by radiological (nuclear) and non-radiological (hazardous) substances released to the environment from the facilities. Note: CNSC staff sample air, water, soil, sediment, vegetation (such as grass) and foodstuffs (such as meat and produce) in public areas outside but in the vicinity of a selected facility. They then analyze the samples and compare contamination levels to federal and/or provincial guidelines to confirm that the public and the environment in the vicinity are safe and there are no health effects as a result of facility operations. Some examples of facilities where IEMP occurs includeuranium mines and mills, processing facilities, nuclear power plants, research reactors and waste management facilities.

independent system (système indépendant)

A system capable of performing its required function while remaining unaffected by the operation or failure of another system.

Indian (Indien)

See Aboriginal peoples of Canada.

indictable conviction (condamnation pour acte criminel)

A category of conviction under Canada’s Criminal Code reserved for more serious offences such as murder, acts of terrorism, robbery, drug trafficking, treason and certain types of sexual assaults.

Indigenous peoples (Autochtones)

Includes the First Nations, Inuit and Métis people of Canada. See also Aboriginal peoples of Canada.

indirect (in vitro) radiobioassay (essai biologique indirect [mesures in vitro])

See bioassay.

indirect bioassay (essai biologique indirect)

See bioassay.

indirect effect (effet indirect)

A secondary environmental effect that occurs as a result of a change that a project may cause in the environment. An indirect effect is at least one step removed from a project activity in terms of cause–effect linkages.

indirect regulatory activities (activités de réglementation indirectes)

Those activities that are in support of direct regulatory activities, such as management, training, administration, human resources, finance, information technology services and the preparation of documents, including policies, standards, guides, procedures and notices. (Source: Canadian Nuclear Safety Commission Cost Recovery Fees Regulations)

industrial or research accelerator (accélérateur industriel ou de recherche)

A particle accelerator that is used solely for industrial or research purposes. Note: In instances where research is to be conducted using an accelerator that is primarily being used for other applications, the accelerator should be licensed according to its primary intended use.

industrial radiography (gammagraphie industrielle)

The use of certified exposure devices to conduct the non‑destructive examination of the structure of welds, castings and building components. Also called gamma radiography.

industrial safety accident rate (ISAR) (taux d’accident de travail)

A measure of the number of lost-time injuries for a defined number of hours worked. Note: In the Canadian nuclear power industry, the defined number is 200,000 hours worked by nuclear power plant personnel. See also lost-time injury.


See International Nuclear and Radiological Event Scale.


Information Circular (IAEA publication)

initial conditions (conditions initiales)

The values of variables in a mathematical model that are assumed at the beginning of the time period considered in the model.

initiating event (événement initiateur)

An event that initiates a sequence of events that could lead to a severe accident in the absence of action by a system important to safety, or an event involving a system important to safety that initiates a sequence of events that could have led to a severe accident if other systems important to safety had not functioned. See also postulated initiating event.

initiating parameter (paramètre initiateur)

The physical property being measured or monitored by the triggering device for a special safety system or its subsystems.

inner area (zone intérieure)

An area inside a protected area that is surrounded by a barrier or structure that meets the requirements of section 13. (Source: Nuclear Security Regulations)

inner maze entrance (entrée du labyrinthe interne)

The point at which the entrance maze merges with the treatment room containing Class II prescribed equipment.


See Institute of Nuclear Power Operations.

in‑service inspection (ISI) (inspection en service)

Non‑destructive examination of structures, systems and/or components, performed to provide information about their current condition and identify any damage, defect or degradation that may have occurred. See also periodic inspection.

in‑service verification (vérification en service)

With respect to nuclear criticality safety, periodic verification of the integrity of a neutron absorber system subsequent to installation.

in situ experiment (expérience in situ)

Neutron multiplication or other nuclear reactivity-determining measurement on a subcritical fissile assembly where protection of personnel against the consequences of a criticality accident is not provided. This definition applies to nuclear criticality safety.

in vitro bioassay (essai biologique in vitro)

See bioassay.

in vivo bioassay (essai biologique direct [mesures in vivo])

See bioassay.

insider threat(menace interne)

An individual with authorized access to a nuclear facility or a means of transportation, who might attempt unauthorized removal or sabotage, or who could aid outsiders to do so.

inspection (inspection)

For maintenance purposes, an examination, observation, measurement or test undertaken to assess the condition of a structure, system or component.


A form of compliance verification independently carried out by the CNSC during which it gathers information, analyzes data and records results for the purpose of evaluating whether an activity is in compliance with regulatory requirements.

Note: The Commission may designate non‑CNSC persons as inspectors; IAEA inspection teams may also participate in this process.

inspector (inspecteur)

A person designated as an inspector under section 29. (Source: Nuclear Safety and Control Act)

Note: Inspectors lead inspections of licensed activities. An inspector may be a CNSC employee or a person otherwise employed under an arrangement with the CNSC.


For safeguards, see International Atomic Energy Agency inspector.

install (installer [montage/démontage])

Mount and dismount a radiation device into its measuring position within a location authorized by a licence (part of the licensed activity of servicing, installation and dismantling of devices containing radioisotopes).

Institute of Nuclear Power Operations (INPO) (Institute of Nuclear Power Operations [INPO])

A not-for-profit organization with the stated mission of promoting the highest levels of safety and reliability in the operation of commercial nuclear power plants. INPO was established by the nuclear power industry in 1979.

institutional controls (contrôles institutionnels)

The control of residual risks at a site after it has been decommissioned. Institutional controls can include active measures (those requiring activities on the site such as water treatment, monitoring, surveillance and maintenance) and passive measures (those not requiring activities on the site, such as land use restrictions or markers).

instruction (instruction)

See training.

instructional program (programme d’enseignement)

See training program.

instructional strategy (stratégie d’enseignement)

The combination of media, methods and environment used in the delivery of training:

  • method: the type of learning activity or instructional event
  • media: the means of delivering instructional activities to the trainee, such as computers or printed texts
  • environment: the learning activity’s location, such as a classroom, workplace or home
instrument or article (appareils ou objets)

Any tool, implement or object, or its components, that encloses nuclear substances and that is fabricated for a particular use other than solely for enclosing those nuclear substances. (Source: Packaging and Transport of Nuclear Substances Regulations, 2015)

intake (incorporation)

The amount of a radionuclide, measured in becquerels, taken into a body by inhalation, absorption through the skin, injection or ingestion, or through wounds.

integrated implementation plan (IIP) (plan intégré de mise en œuvre [PIMO])

A plan that considers the scope and schedule of safety improvements to support continued operation of a facility, based on the results of a periodic safety review.

integrated system validation (validation des systèmes intégrés)

An evaluation, using performance-based tests, to determine whether an integrated system’s design (that is, hardware, software and personnel elements) meets performance requirements and supports the facility’s safe operation.

intended end use (utilisation ultime prévue)

The declared purpose or use of an imported or exported good or service (for example, industrial irradiation, industrial radiography, teletherapy, blood irradiation).

intermediate bulk container (IBC) (grand récipient pour vrac [GRV])

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

Note: In the IAEA Regulations, an intermediate bulk container means a portable packaging that has a capacity of not more than 3 m3; is designed for mechanical handling; and is resistant to the stresses produced in handling and transport, as determined by tests.

intermediate consignee (destinataire intermédiare)

A person who is not the importer but who acts to facilitate the transfer of a nuclear substance, prescribed equipment or prescribed information to the importer within the recipient jurisdiction. However, a person associated solely with the transport of the nuclear substance, prescribed equipment or prescribed information (for example, a carrier or freight forwarder) is not considered an intermediate consignee.

intermediate-level waste (déchet de moyenne activité)

Radioactive solid waste that typically exhibits levels of penetrating radiation sufficient to require shielding during handling and interim storage.

internal dosimetry (dosimétrie interne)

See dosimetry types.

internal event (événement interne)

Any event that proceeds from a human error or from a failure of a structure, system or component.

internal hazard (danger interne)

A hazard that originates from the sources located on the site of a nuclear facility (both inside and outside facility buildings). Some examples of internal hazards are internal fires, internal floods, turbine missiles, onsite transportation accidents and releases of toxic substances from onsite storage facilities.

International Atomic Energy Agency (IAEA) (Agence internationale de l’énergie atomique [AIEA])

An independent international organization related to the United Nations system. The IAEA works with its Member States and multiple partners worldwide to promote safe, secure and peaceful nuclear technologies. The IAEA reports annually to the UN General Assembly and, when appropriate, to the Security Council regarding non‑compliance by States with respect to their safeguards obligations, as well as on matters relating to international peace and security.

International Atomic Energy Agency inspector (inspecteur de l’Agence internationale de l’énergie atomique)

An International Atomic Energy Agency (IAEA) officer appointed by the IAEA Director General, approved by the IAEA Board of Governors to perform safeguards inspections, and proposed to and accepted by the Government of Canada to perform safeguards inspections in Canada. IAEA inspectors are granted privileges and immunities necessary for the performance of their functions. See also inspector.

International Atomic Energy Agency seal (sceau de l’Agence internationale de l’énergie atomique)

A tamper-indicating device used to join moveable segments of a containment in a way that makes it difficult to access its contents without opening the seal or breaking the containment. See also containment.

International Commission on Radiological Protection (ICRP) (Commission internationale de protection radiologique)

The international organization that has developed standards and concepts for ionizing radiation protection.

International Maritime Dangerous Goods Code (Code maritime international des marchandises dangereuses)

The document of that name published by the International Maritime Organization, as amended from time to time. (Source: Packaging and Transport of Nuclear Substances Regulations, 2015)

International Nuclear and Radiological Event Scale (INES) (Échelle internationale des événements nucléaires et radiologiques [INES])

A seven‑point scale used to promptly and consistently classify nuclear events into safety-significant ratings.

International Reporting System for Operating Experience (IRS) (Système international de notification des incidents [IRS])

A platform for the collection, processing and effective dissemination of construction, operating and decommissioning experience information among regulators in IAEA Member States.

interoperability (interopérabilité)

The capacity to manage and communicate electronic product and project detail between collaborating firms and within individual companies’ design, construction, operations, maintenance, and business process systems.

intervenor (intervenant)

A person who is permitted to intervene at a public hearing under rule 19. (Source: Canadian Nuclear Safety Commission Rules of Procedure).

Note: The intervenor is a person who has an interest, expertise or information useful to the Commission in coming to a decision.

interviewer (intervieweur)

With respect to security, a qualified person, representing a licensee, who conducts investigations and/or security interviews to gather information from an applicant for, or holder of, site access security clearance (SASC), for the purpose of granting, renewing, denying or revoking the SASC.

Inuit (Inuit)

See Aboriginal peoples of Canada or Indigenous peoples.

inventory change (variation de stock)

With respect to safeguards, means an increase or decrease of nuclear material, in terms of batches, in a material balance area. An internal inventory change affects only one material balance area. See also material balance area.

inventory difference (différence d’inventaire)

With respect to nuclear material accounting, the difference between book-adjusted inventory and the physical inventory as reported in the reconciliation statement. Also called material unaccounted for.

inventory verification (vérification du stock)

See physical inventory verification.

investigational level (IL) (niveau d’enquête [NE])

An indicator of intake (in becquerels) of a radioactive substance that requires special monitoring of a worker. Typically the level is expressed as a fraction of the annual limit on intake.

ion exchange process (procédé d’échange d’ions)

A usually reversible exchange of one ion with another, either on a solid surface or within a lattice. Ion exchange is a commonly used method for treating liquid waste.

ionizing radiation (rayonnement ionisant)

For the purposes of radiation protection, radiation capable of producing ion pairs in biological material(s). Note: Ionizing radiation is constantly present in the environment and includes the radiation that comes from both natural and artificial sources, such as cosmic rays, terrestrial sources (radioactive elements in the soil), ambient air (radon), and internal sources (food and drink).

IP‑1 package (colis CI‑1)

See Type IP‑1.

IP‑2 package (colis CI‑2)

See Type IP‑2.

IP‑3 package (colis CI‑3)

See Type IP‑3.


International Physical Protection Advisory Service


See immediate rapid deployment.

irradiated fuel bay (piscine de combustible usé)

See wet storage bay.

irradiated nuclear fuel (combustible nucléaire irradié)

See used nuclear fuel.

irradiation (irradiation)

Exposure to radiation. Note: “exposure” is commonly used to describe radiation doses to people while “irradiation” is more often used for radiation doses to food or industrial objects.

irradiator (irradiateur)

A device that is designed to contain a nuclear substance and to deliver controlled doses of radiation to any target material except persons. (Source: General Nuclear Safety and Control Regulations)


A device that is designed to contain a nuclear substance and to deliver controlled doses of radiation from that substance to any target except persons. (Source: Class II Nuclear Facilities and Prescribed Equipment Regulations)


Integrated Regulatory Review Service


See International Reporting System for Operating Experience.


See industrial safety accident rate.

ISI (inspection en service)

See in‑service inspection.

island load (îlotage)

See house load operation.

island operation (fonctionnement en îlotage)

See house load operation.


International Organization for Standardization

isocentre (isocentre)

For teletherapy equipment, the intersection between the central axis of the primary beam and the axis of gantry rotation.

isolation (isolement)

With respect to radioactive waste, means the physical separation of this waste from people and the environment to make access to the waste difficult.
Note: For deep geological disposal, isolation is provided mainly by the depth of the repository.

isotope (isotope)

A variation in the form of atoms, of the same chemical element, which are distinguished by the number of neutrons in the nucleus. The number of protons remains the same, but the number of neutrons differs. For example, uranium has 16 different isotopes.

isotope production accelerator (accélérateur pour la production d’isotopes)

A particle accelerator that is designed and used for producing nuclear substances by irradiating a target material.


integrated safety review; see periodic safety review

item (article)

With respect to nuclear material accounting, an individually identifiable unit of nuclear material (for example, a fissile assembly or material in bulk form in a container, such as a tank or box, that is kept intact while stored in the material balance area).

items important to safety (dispositifs importants pour la sûreté)

An item that is part of a safety group and/or whose malfunction failure could lead to radiation exposure.

Page details

Date modified: