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REGDOC-3.6, Glossary of CNSC Terminology- Glossary - Q-R


See quality management.

qualification (qualification)

A recognized level of mastery of task performance in a work-related field, which is normally acquired through successful completion of training. Qualification involves mastery of all the knowledge, skills and safety-related attributes required for successful task performance on the job.

qualified (qualifié)

With respect to personnel certification, being eligible and meeting the requirements to be a successful applicant for certification as an RSO.

qualified technician (technicien qualifié)

See breath alcohol technician.

quality management (QM) (gestion de la qualité [GQ])

With respect to nuclear criticality safety, a planned and systematic pattern of all means and actions designed to provide adequate confidence that items or services meet specified requirements and will perform satisfactorily in service.

R (R)

See response.

radiation (rayonnement)

The emission by a nuclear substance, the production using a nuclear substance, or the production at a nuclear facility of, an atomic or subatomic particle or electromagnetic wave with sufficient energy for ionization. (Source: Nuclear Safety and Control Act)

radiation device (appareil à rayonnement)


  1. a device that contains more than the exemption quantity of a nuclear substance and that enables the nuclear substance to be used for its radiation properties; and
  2. a device that contains a radium luminous compound.

(Source: Nuclear Substances and Radiation Devices Regulations)

radiation protection SCA (DSR Radioprotection)

A safety and control area (SCA) that covers the implementation of a radiation protection program in accordance with the Radiation Protection Regulations. The program must ensure that contamination levels and radiation doses received by individuals are monitored, controlled and maintained ALARA. This SCA is one of the 14 within the CNSC SCA Framework.

radiation safety officer (RSO) (responsable de la radioprotection [RRP])

A radiation safety specialist who implements and administers a radiation safety program on a day-to-day basis. Note: As specified in subsection 15.04 of the Class II Nuclear Facilities and Prescribed Equipment Regulations, the Commission or a designated officer may certify a person for the position of radiation safety officer if the person has successfully completed an examination that is recognized by the Commission and, in the opinion of the Commission or designated officer, the person is capable of performing the duties of the position.

radiation survey meter (radiamètre)

An instrument that is capable of measuring radiation dose rates. (Sources: Class II Nuclear Facilities and Prescribed Equipment Regulations; Nuclear Substances and Radiation Devices Regulations)

radiation weighting factor (wR) (facteur de pondération radiologique [wR])

A number by which the absorbed dose in a tissue or organ is multiplied to reflect the relative biological effectiveness (harm) of the radiation in inducing stochastic effects at low doses, the result being the equivalent dose.

radioactive atmosphere (atmosphère radioactive)

See dosimetry types.

radioactive decay (désintégration radioactive)

The spontaneous transformation of one radioisotope into one or more different isotopes (known as decay products or daughter products), accompanied by a decrease in radioactivity (compared to the parent material). This transformation takes place over a defined period of time (known as a half-life), as a result of electron capture; fission; or the emission of alpha particles, beta particles, or photons (gamma radiation or X‑rays) from the nucleus of an unstable atom. Each isotope in the sequence (known as a decay chain) decays to the next until it forms a stable, less energetic end product. In addition, radioactive decay may refer to gamma‑ray and conversion electron emission, which only reduces the excitation energy of the nucleus.

radioactive material (matière radioactive)

A nuclear substance that is a radioactive material, as defined in the IAEA Regulations. (Source: Packaging and Transport of Nuclear Substances Regulations, 2015)

Note: The IAEA Regulations identify this substance as any material containing radionuclides where both the activity concentration and the total activity in a consignment exceed the values further specified by the IAEA Regulations.


For purposes of nuclear security, any material that emits one or more types of ionizing radiation, such as alpha or beta particles, neutrons or gamma rays.

radioactive source (source radioactive)

Radioactive material that is permanently sealed in a capsule or closely bonded in a solid form, and which is not exempt from regulatory control. This term also means any radioactive material released if the radioactive source is leaking or broken, but does not mean material encapsulated for disposal, or nuclear material within the nuclear fuel cycles of research and power reactors.

radioactive source teletherapy machine (appareil de téléthérapie à source radioactive)

A teletherapy machine that is designed to deliver doses of radiation produced by a nuclear substance. (Sources: General Nuclear Safety and Control Regulations; Class II Nuclear Facilities and Prescribed Equipment Regulations)

radioactive waste (déchets radioactifs)

For the purposes of waste management, any material (liquid, gaseous or solid) that contains a radioactive nuclear substance, as defined in section 2 of the Nuclear Safety and Control Act, and which the owner has declared to be waste. In addition to containing nuclear substances, radioactive waste may also contain non‑radioactive hazardous substances, as defined in section 1 of the General Nuclear Safety and Control Regulations.

radioactivity (radioactivité)

The spontaneous transformation of an atom’s nucleus by expulsion of particles. Radioactivity can be accompanied by electromagnetic radiation. Solids, liquids or gases can be radioactive.

radiography camera (caméra de gammagraphie)

See exposure container.

radioiodine (iode radioactif)

A substance containing radioactive iodine in a chemical form that has a metabolic pathway similar to iodide, such as inorganic compounds and metabolic forms of organic iodine that are broken down in a living organism. Some examples are the radioisotopes iodine‑125 and iodine‑131.

radioiodine bioassay (essai biologique visant à détecter l’iode radioactif)

The measurement of the amount of radioiodine in the body, for the purpose of finding out the associated committed effective dose.

radioisotope (radio‑isotope)

See isotope.

radioisotope laboratory (laboratoire de radio‑isotopes)

See nuclear substance laboratory.

radionuclide (radionucléide)

A material with an unstable atomic nucleus that spontaneously decays or disintegrates, producing radiation. Nuclei are distinguished by their mass and atomic number.

radiosensitivity (radiosensibilité)

The relative susceptibility to damage from radiation for cells, tissues, organs and organisms. Not to be confused with radiosusceptibility, which is the relative susceptibility to develop genomic instability and cancer.

radon decay product (produit de désintégration du radon)

See radon progeny.

radon progeny (produit de filiation du radon)

The following radioactive decay products of radon‑222: bismuth‑214, lead‑214, polonium‑214 and polonium‑218. (Sources: Radiation Protection Regulations; Packaging and Transport of Nuclear Substances Regulations, 2015)

Note: These nuclear substances are emitted when radon gas undergoes radioactive decay. Polonium‑218 and polonium‑214 emit alpha particles and are responsible for the bulk of the dose to the respiratory tract resulting from inhaled radon. All four of these short-lived radon progeny have half-lives of less than 30 minutes. Also known as radon decay product.

random testing (test aléatoire de dépistage)

With respect to fitness for duty, a statistically random and unannounced basis for selecting which workers designated in safety-critical positions will be subject to alcohol and drug testing, so that each worker has an equal probability of being selected and tested. See also safety-critical position.

Raschig ring (anneau de Raschig)

A small, hollow, borosilicate-glass cylinder having approximately equal length and diameter.


risk achievement worth; see importance measures

RCA (analyse des causes fondamentales)

See root-cause analysis.


See reliability-centred maintenance.


reactor coolant system


risk decrease ratio; see importance measures

reactivity (réactivité)

The quantity (keff ‑ 1) / keff, where keff is the effective neutron multiplication factor. The reactivity of a subcritical assembly is a negative quantity indicating the degree of subcriticality. The reactivity of a critical assembly is zero.

reactivity addition (addition de réactivité)

A modification of a fissile assembly that results in a positive incremental change of reactivity.

reactor containment (confinement du réacteur)

See containment.

reactor coolant system (système de refroidissement du coeur)

See primary heat transport system.

reactor facility (installation dotée d’un réacteur)

Any fission or fusion reactor, including structures, systems and components:

  • that are necessary for shutting down the reactor, ensuring that it can be kept in a safe shutdown state
  • that may contain radioactive material and which cannot be reliably isolated from the reactor
  • whose failure can lead to a limiting accident for the reactor
  • that are tightly integrated into the operation of the nuclear facility
  • that are needed to maintain security and safeguards
reactor operator (opérateur de réacteur)

The person in a reactor facility who is responsible for operating and monitoring the systems of a reactor unit, in accordance with the licence, policies and procedures. Also called authorized nuclear operator; control room operator.

reactor state (état du réacteur)

See plant state.

reactor trip (arrêt automatique du réacteur)

A reduction in reactor power initiated by any of a reactor’s safety circuits. A reactor trip rapidly shuts down the reactor in response to the detection of certain abnormal and potentially dangerous conditions or by operator decision.

reasonable grounds testing (test de dépistage pour motifs raisonnables)

With respect to fitness for duty, an element of for-cause testing, where workers in safety-critical or safety-sensitive positions are required to submit to testing when there is reasonable cause to believe, through observed behaviour, physical condition or after receiving credible information, that the individual is unfit to perform their duties, due to the adverse effects of alcohol or drug use. See also fitness for duty; for-cause testing; post-incident testing; pre-placement testing.

re‑batching (remise en lots)

With respect to nuclear material accounting, accounting for changes to the physical inventory (such as chemical and physical form, irradiation status) of an individual batch of nuclear material.

receptor (récepteur)

Any person or environmental entity that is exposed to radiation, a hazardous substance, or both. A receptor is usually an organism or a population, but it could also be an abiotic entity such as surface water or sediment.

recognized educational institution (institution reconnue)

A Canadian educational institution with a federal or provincial charter, or a foreign educational institution whose diplomas are accepted by a recognized Canadian institution or university.

recognized university (université reconnue)

A Canadian university with a federal or provincial charter, or a foreign university whose degrees are accepted by a recognized Canadian university.

record (document)

Has the meaning assigned to that word by section 3 of the Access to Information Act. (Source: Nuclear Safety and Control Act)

Note: The Access to Information Act states that a record means any documentary material, regardless of medium or form.

redundancy (redondance)

The provision of alternative (identical or diverse) structures, systems and components (SSCs), so that any one can perform the required function regardless of the state of operation or failure of any other SSC.

reference value (valeur de référence)

See conventionally true value.

refresher training (formation de recyclage)

See continuing training.

region (région)

With respect to site evaluation for a new nuclear facility, a specific area to be studied. The spatial characteristics of a region will vary for each hazard being studied. For example, the region being investigated for groundwater effects of a nuclear power plant may be substantially different from the region being investigated for effects due to atmospheric releases.

registered user (usager inscrit)

A person who has received confirmation under subsection 19(3) from the Commission that their use of a package has been registered. (Source: Packaging and Transport of Nuclear Substances Regulations, 2015)

Registrar (registraire)

The Registrar of the Commission.

(Sources: Canadian Nuclear Safety Commission Rules of Procedure; Canadian Nuclear Safety Commission By-laws)

Note: The Canadian Nuclear Safety Commission Rules of Procedure further state that the Registrar is appointed under section 16 of the NSCA.

regulation (règlement)

The “operational” part of a law. In Canada, a regulation is made under a specified Act, the means by which Parliament makes laws. A regulation commonly deals with matters such as what is meant by certain terms used in the Act, procedures and processes that must be followed or standards that must be met in order to comply with the Act. Often referred to as delegated legislation or subordinate legislation, a regulation is not made by Parliament but by someone to whom Parliament has delegated the authority to make it. The Commission has the authority under the Nuclear Safety and Control Act (NSCA) to make regulations, with the approval of the Governor in Council, for matters related to its mandate.

regulatory hold point (point d’arrêt réglementaire)

A commissioning activity that requires approval of the Canadian Nuclear Safety Commission in order for commissioning to proceed.

regulatory scrutiny (contrôle réglementaire)

A regulator’s enforcement option to focus efforts on specific areas of non‑compliance. This scrutiny may include:

  • increasing the frequency of inspections or of meetings with the licensee
  • adding more reporting requirements
  • broadening the scope of inspections
  • modifying inspection techniques/strategies (for example, root-cause analysis, augmented inspections)
regulatory undertaking (travail réglementaire)

Outage work required by a code or a standard that is referenced in a licence (mandatory work) or other work that was committed by the licensee to the CNSC through formal correspondence (committed work) including:

  • periodic inspection program (PIP) inspections in the last outage of a PIP cycle
  • PIP work that is required to allow the extension of an existing disposition that will expire before the next planned outage
related experience (expérience pertinente)

For certification purposes, the experience a person has gained in performing duties related to those of the position being sought.

reliability (fiabilité)

The ability of a structure, system or component to perform, in accordance with its defined specifications, its required function under given conditions for a defined time period or upon demand.

reliability-centred maintenance (RCM) (entretien axé sur la fiabilité)

A series of orderly steps for identifying system and subsystem functions, functional failures and dominant failure modes; prioritizing them; and selecting applicable and effective preventive maintenance tasks to address the classified failure modes.

reliability monitoring (surveillance de la fiabilité)

Direct monitoring of reliability parameters of a structure, system or component (for example, failure frequency, downtime due to the maintenance activities, or outage rate).

reliability targets (objectifs de fiabilité)

The reliability goals to be achieved by the plant systems. The purpose of these targets is to compare them with actual plant performance, in order to identify deviations from expected performance.

remediation (remise en état)

Any measures that may be carried out to reduce the radiation exposure due to contamination of land areas through actions applied to the contamination itself (the source) or to the exposure pathways to humans.
Note: Often remediation is used to restore land areas to conditions suitable for limited use under institutional control.

remote control (télécommande)

For exposure devices, a device that enables the sealed source assembly to be moved to and from a working position by the operator while at a safe distance from the exposure container. Note: The remote control includes the control mechanism and also, where applicable, the control cable, control cable sheath and necessary connections and attachments. Also called control mechanism; cranking mechanism; drive mechanism.

removal site (site d’extraction)

A place at which uranium is removed from its place of natural deposit by means of surface activities for the purpose of evaluating a potential ore body. (Source: Uranium Mines and Mills Regulations)

repair (réparation)

Any activity that allows a failed or degraded structure, system or component to function as per original design; repair may be permanent or temporary.

replacement (remplacement)

For reactor facilities, the substitution of a structure, system or component (SSC) with an identical SSC or with an SSC that has been approved as equivalent through an equivalency process.

representative nuclear criticality accident (accident de criticité nucléaire représentatif)

A postulated nuclear criticality accident that is used to demonstrate compliance with the CNSC criticality safety requirements on the mitigation of nuclear criticality accident consequences.

requalification training (formation de requalification)

See continuing training.

residual heat (chaleur résiduelle)

The sum of heat originating from radioactive decay, fission in the fuel in the shutdown state, and the heat stored in structures, systems and components.

response (R) (réponse [R])

With respect to dosimetry, the result of a dose measurement under defined conditions divided by the conventionally true dose that would be received under those conditions.


See emergency response.

response unit (unité d’intervention)

With respect to nuclear security, a team that comprises members of the onsite nuclear response force at a nuclear facility and is assigned to mount an effective intervention there.

responsible designer (concepteur responsable)

An organization to which the design authority has assigned responsibility for the design of specific parts of a nuclear facility.

responsible health physicist (spécialiste principal en radioprotection)

See senior health physicist.

restricted area (zone à accès restreint)

An area to which public access is controlled in order to protect individuals from exposure to radiation and radioactive materials. Also called controlled area.

retained waste (déchets conservés)

With respect to nuclear material accounting, a subset of Group 1A nuclear material that has been identified as unrecoverable and is stored in the material balance area. This Group 1A nuclear material may be transferred to retained waste upon approval of CNSC staff. After transfer, the only reporting requirement is to provide an inventory listing upon request.


risk increase ratio; see importance measures

risk (risque)

The chance of injury or loss, defined as a measure of the probability and severity of an adverse effect (consequence) to health, property, the environment or other things of value; mathematically, risk is the probability of occurrence (likelihood) of an event multiplied by its magnitude (severity).

risk achievement worth (RAW) (rapport d’augmentation du risque [RAR])

See importance measures.

risk assessment (évaluation du risque)

An assessment of the radiological risks associated with normal operation and potential accidents involving a nuclear substance or licensed activity. A risk assessment will normally include consequence assessment and associated probabilities.

risk decrease ratio (RDR) (rapport de réduction du risque [RRR])

See importance measures.

risk increase ratio (RIR) (rapport d’augmentation du risque [RAR])

See importance measures.

risk-informed approach (approche en fonction du risque)

An approach to decision making that includes risk insights as one of the factors in determining a course of action.

risk reduction worth (RRW) (rapport de réduction du risque [RRR])

See importance measures.

risk-significant radioactive sources (sources radioactives à risque élevé)

Any radionuclide identified as a Category 1 or Category 2 radioactive source in table 1 of annex I of the International Atomic Energy Agency’s Code of Conduct on the Safety and Security of Radioactive Sources [8].

root-cause analysis (RCA) (analyse des causes fondamentales)

An objective, structured, systematic and comprehensive analysis for determining the underlying causes of a situation or event.

routine bioassay (essai biologique courant)

Any bioassay that involves collecting and analyzing samples or taking measurements on a body at scheduled intervals, or at predetermined times, during normal operations.


radiation personal protective equipment


risk reduction worth; see importance measures


radiation safety data sheets (associated with the Workplace Hazardous Materials Information System)


See radiation safety officer.

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