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

National Dose Registry (NDR) (Fichier dosimétrique national [FDN])

The centralized database of occupational radiation exposure records, managed, updated and maintained by the Radiation Protection Bureau of Health Canada. The NDR publishes annual reports on occupational dose information and trends, according to job type, over the lifetime of registered individuals.

National Non‑Destructive Testing (NDT) Certification Body (NCB) (Organisme de certification national [OCN] en essais non destructifs [END])

The division of Natural Resources Canada that administers, on behalf of the CNSC, the written examination for candidates for the position of exposure device operator.

natural analogues (analogues naturels)

Natural conditions or processes, occurring over long periods of time, that are the same as or similar to those known or predicted to occur in some part of a waste management system.

natural phenomenon event (phénomène naturel)

An earthquake, flood, tornado, tsunami, hurricane or other event that occurs in the natural environment and could adversely affect safety. Natural phenomenon events may be credible or incredible, depending on their likelihood of occurrence.

natural uranium (uranium naturel)

Uranium that contains uranium‑235 in a concentration that is normally found in nature. (Source: Nuclear Substances and Radiation Devices Regulations)

Note 1: With respect to nuclear criticality safety, this concentration of this isotope is equal to or less than 0.71 percent by weight.

Note 2: With respect to packaging and transport of nuclear substances, natural uranium means uranium (which may be chemically separated) containing the naturally occurring distribution of uranium isotopes (approximately 99.28 percent uranium‑238, and 0.72 percent uranium‑235 by mass). A very small mass percentage of uranium‑234 is present.


See National Non‑Destructive Testing (NDT) Certification Body.


See nuclear criticality safety.


nuclear criticality safety evaluation

NCS staff (personnel de SCN)

See nuclear criticality safety staff.


See National Dose Registry.


non‑destructive testing; see also National Non‑Destructive Testing (NDT) Certification Body


See nuclear emergency management.


See Nuclear Emergency Organization.

neutron (neutron)

A subatomic particle found in the nucleus of atoms. A neutron has a mass of about 1.6 x 10‑27 kg and no electric charge.

neutron absorber (absorbeur de neutrons)

A neutron-capture material; that is, asubstance with a large neutron absorption cross-section. When neutron absorption is not desired, a neutron absorber may be called a neutron poison. Some examples of neutron absorbers are:

  • boron, used in some shutdown systems
  • some of the products generated during fission that have a high neutron absorption cross-section, such as xenon‑135 and samarium‑149
neutron absorber system (système absorbeur de neutrons)

Any combination of fixed neutron absorbers, fixed moderators, and other materials with an assigned nuclear criticality safety function.

neutron multiplication (multiplication des neutrons)

The process in which a neutron produces on the average more than one neutron in a medium containing fissile material.

neutron poison (poison neutronique)

See neutron absorber.

neutron radiation (rayonnement neutronique)

Radiation that involves free neutrons (unstable subatomic particles with no electric charge) released from atoms during the nuclear fission or fusion process. When absorbed into an atom, the free neutrons can make that atom unstable, and more likely to decay and produce ionizing radiation. Neutron radiation has a high penetrating capability.


See nuclear energy worker.

night shift (quart de nuit)

Shift that includes any time at work between 2 a.m. and 6 a.m.

NOA (avis d’évaluation – RIEN À SIGNALER )

See NOA – NO ADVERSE INFO or Notice of Assessment (NOA) – INSUFFICIENT INFO.

NOA – NO ADVERSE INFO (avis d’évaluation – RIEN À SIGNALER)

A notice of assessment issued by the Canadian Security Intelligence Service, indicating that there is no adverse information regarding an applicant’s loyalty to Canada.

non‑fixed contamination (contamination non fixée)

As defined in the IAEA Regulations. (Source: Packaging and Transport of Nuclear Substances Regulations, 2015)

Note: In the IAEA Regulations, non‑fixed contamination means contamination that can be removed from a surface during routine conditions of transport.

non‑ionizing radiation (rayonnement non ionisant)

Radiation that has a lower energy level than ionizing radiation and cannot remove an electron from an atom and produce ions. Examples include ultraviolet (UV), visible light, infrared, microwaves and radio waves. This type of radiation is not regulated by the Nuclear Safety and Control Act.

non‑routine bioassay (essai biologique spécial)

Any bioassay that is implemented as part of an ad hoc response to a particular circumstance, such as a known or suspected intake of radioactive material due to an abnormal incident in the workplace. Also called ad hoc bioassay; special bioassay.

non‑safeguarded material (matières non visées par les garanties)

Source material and special fissionable material under IAEA safeguards (agreement INFCIRC/164) that has not reached the stage of the nuclear fuel cycle as described in article 34(c) of the agreement.

non‑stochastic effect (effet non stochastique)

See deterministic effect.

normal operation (exploitation normale)

The operation of a nuclear facility within specified operational limits and conditions, including (where applicable) start‑up, power operation, shutting down, shutdown, maintenance, testing and refuelling. In nuclear reactors, normal operation is a plant state.

Notice of Assessment (NOA) – INSUFFICIENT INFO (avis d’évaluation – RENSEIGNEMENTS INSUFFISANTS)

A notice of assessment issued by the Canadian Security Intelligence Service (CSIS) indicating that there is insufficient information for CSIS to provide a meaningful assessment on the loyalty to Canada of an applicant for site access security clearance, usually due to lack of traceable history or residency.

NPP (centrale nucléaire)

See nuclear power plant.


Treaty on the Non-Proliferation of Nuclear Weapons (also referred to as the Non-Proliferation Treaty or the Nuclear Non-Proliferation Treaty).

NRC (CNRC ou NRC des États‑Unis)

National Research Council or see U.S. Nuclear Regulatory Commission.


See Nuclear Safety and Control Act.


See Nuclear Suppliers Group.


See nuclear security officer.

nuclear activity

See activity or licensed activity.

Categories in the Nuclear Non-proliferation Import and Export Control Regulations that group controlled nuclear substances, equipment and information. Part A of the schedule in the Regulations lists nuclear items under each of these three categories, and Part B lists nuclear-related dual-use items under the same categories. Note: The term dual use refers to the potential for a nuclear-related item to be used not only in civilian applications, but also in a nuclear weapons program. Also called controlled nuclear substances, equipment and information. See also controlled nuclear equipment; controlled nuclear information; controlled nuclear substance.

nuclear criticality (criticité nucléaire)

A self-sustaining chain reaction of nuclear fission. (Source: Nuclear Substances and Radiation Devices Regulations)

Note: With respect to nuclear criticality safety, pertaining to a system that supports a sustained fission chain reaction.

nuclear criticality process evaluation (évaluation de procédé en matière de criticité nucléaire)

A document that identifies and defines all known nuclear criticality safety concerns; documents nuclear criticality safety assumptions, requirements, limits and controls; and demonstrates subcriticality. Also called process evaluation.

nuclear criticality safety (NCS) (sûreté‑criticité nucléaire [SCN])

Protection against the consequences of a criticality accident, preferably by prevention of the accident.

nuclear criticality safety control (contrôle de sûreté‑criticité nucléaire)

Structures, systems, equipment, components, and activities of personnel that are relied on to prevent accidents at a facility or to mitigate their potential consequences. Also called criticality safety control. Note: This control does not limit the licensee from identifying additional structures, systems, equipment, components, or activities of personnel (that is, beyond those in the minimum set necessary for compliance with the performance requirements) as items relied on for safety. All safety controls (active engineered control, passive engineered control, simple administrative control and enhanced administrative control) are nuclear criticality safety controls.

nuclear criticality safety staff (NCS staff) (personnel de sûreté‑criticité nucléaire [personnel de SCN])

Specialists skilled in the techniques of nuclear criticality safety assessment and familiar with plant operations while, to the extent practicable, administratively independent of process supervision. Also called criticality safety staff.

nuclear emergency (urgence nucléaire)

An abnormal situation that may increase the risk of harm to the health and safety of persons, the environment or national security, and that requires the immediate attention of the CNSC. Some examples are an emergency at a nuclear facility; an emergency involving a nuclear-powered vessel in a Canadian port; an emergency involving the loss, theft or discovery of radioactive material; or a terrorist attack using radioactive material.

nuclear emergency management (NEM) (gestion des urgences nucléaires [GUN])

The organized effort to prevent, prepare for, respond to and recover from a nuclear emergency.

nuclear emergency management program (programme de gestion des urgences nucléaires)

The comprehensive program described by the CNSC’s nuclear emergency management policy document together with the nuclear emergency management plan and approved supporting procedures, guidelines and other documents.

Nuclear Emergency Organization (NEO) (Organisation d’urgence nucléaire [OUN])

A CNSC body that carries out all CNSC activities needed to effectively respond to a nuclear emergency.

nuclear energy (énergie nucléaire)

Any form of energy released in the course of nuclear fission or nuclear fusion or of any other nuclear transmutation. (Source: Nuclear Safety and Control Act)

Nuclear Energy Agency (NEA) (Agence pour l’énergie nucléaire [AEN])

A specialized agency within the Organisation for Economic Co‑operation and Development. The mission of the NEA is to assist its member countries in maintaining and further developing, through international cooperation, the scientific, technological and legal bases required for the safe, environmentally friendly and economical use of nuclear energy for peaceful purposes.

nuclear energy worker (NEW) (travailleur du secteur nucléaire [TSN])

A person who is required, in the course of the person’s business or occupation in connection with a nuclear substance or nuclear facility, to perform duties in such circumstances that there is a reasonable probability that the person may receive a dose of radiation that is greater than the prescribed limit for the general public. (Source: Nuclear Safety and Control Act)

nuclear facility (installation nucléaire)

Any of the following facilities, namely,

  1. a nuclear fission or fusion reactor or subcritical nuclear assembly,
  2. a particle accelerator,
  3. a uranium or thorium mine or mill,
  4. a plant for the processing, reprocessing or separation of an isotope of uranium, thorium or plutonium,
  5. a plant for the manufacture of a product from uranium, thorium or plutonium,
  6. a plant for the processing or use, in a quantity greater than 1015 Bq per calendar year, of nuclear substances other than uranium, thorium or plutonium,
  7. a facility for the disposal of a nuclear substance generated at another nuclear facility,
  8. a vehicle that is equipped with a nuclear reactor, and
  9. any other facility that is prescribed for the development, production or use of nuclear energy or the production, possession or use of a nuclear substance, prescribed equipment or prescribed information, and includes, where applicable, the land on which the facility is located, a building that forms part of, or equipment used in conjunction with, the facility and any system for the management, storage or disposal of a nuclear substance.

(Source: Nuclear Safety and Control Act)


[Any of the following:]

  1. any nuclear reactor, including a reactor installed on a vessel, vehicle, aircraft or space object for use as an energy source in order to propel the vessel, vehicle, aircraft or space object or for any other purpose, and
  2. any plant or conveyance used for the production, storage, processing or transport of nuclear material or radioactive material

(Source:Criminal Code)


With respect to safeguards, see facility.

nuclear facility perimeter (périmètre de l’installation nucléaire)

The outer boundary of a geographical area that contains the licensed facility and within which the management of the licensed facility may directly initiate emergency actions. The nuclear facility perimeter typically encloses the area within the security fence or other designated property marker.

nuclear loss (consommation)

The loss of nuclear material due to its transformation into other element(s) or isotope(s) as a result of nuclear reactions. Nuclear loss also includes burnup of nuclear material in a reactor and radioactive decay (for example, plutonium‑241).

nuclear material (matières nucléaires)

With respect to safeguards, means plutonium‑239, uranium‑233, uranium enriched in the isotopes of 235 or 233, uranium containing the mixture of isotopes occurring in nature, uranium depleted in isotope 235 and thorium. The term nuclear material does not apply to uranium or thorium in ore, ore residue or other naturally occurring materials.

nuclear medicine room (salle de médecine nucléaire)

Any area or enclosure where nuclear substances are prepared for or administered to a person (via injection, inhalation or ingestion) for the purpose of diagnosing or treating disease and for human research studies (excluding medical diagnostic X‑rays or the medical use of sealed sources for brachytherapy or teletherapy treatments).

nuclear medicine technologist (technologue en médecine nucléaire)

A medical radiation technologist certified by the Canadian Association of Medical Radiation Technologists. Working in the field of nuclear medicine, this technologist performs various duties. For example, the technologist prepares and administers radiopharmaceuticals, takes images of different organs and bodily structures, uses computers to process data and enhance images, analyzes biological specimens and works closely with all members of the healthcare team.

nuclear poison (poison nucléaire)

See neutron absorber.

nuclear power plant (NPP) (centrale nucléaire)

A nuclear facility consisting of any fission-reactor installation that has been constructed to generate electricity on a commercial scale. (Source: Nuclear Security Regulations)

Note 1: An NPP may include more than one nuclear reactor.

Note 2: An NPP may also be constructed with the intent to provide heat or steam on a commercial scale.

nuclear production (production nucléaire)

The generation of special fissionable material through the irradiation of fertile material in a reactor.

Nuclear Regulatory Commission (NRC) (Nuclear Regulatory Commission [NRC])

See U.S. Nuclear Regulatory Commission.

Nuclear Safety and Control Act (NSCA) (Loi sur la sûreté et la réglementation nucléaires [LSRN])

An Act of Parliament that came into force on May 31, 2000, replacing the Atomic Energy Control Act. The NSCA provides the Canadian Nuclear Safety Commission with its regulatory authority.

nuclear security officer (NSO) (agent de sécurité nucléaire [ASN])

A person whose function is to provide security at a high-security site and to whom an authorization referred to in subsection 18(2) has been issued. (Source: Nuclear Security Regulations)

nuclear substance (substance nucléaire)


  1. deuterium, thorium, uranium or an element with an atomic number greater than 92;
  2. a derivative or compound of deuterium, thorium, uranium or of an element with an atomic number greater than 92;
  3. a radioactive nuclide;
  4. a substance that is prescribed as being capable of releasing nuclear energy or as being required for the production or use of nuclear energy;
  5. a radioactive by‑product of the development, production or use of nuclear energy; and
  6. a radioactive substance or radioactive thing that was used for the development or production, or in connection with the use, of nuclear energy.

(Source: Nuclear Safety and Control Act)

nuclear substance laboratory (laboratoire de substances nucléaires)

A laboratory in which unsealed sources are used. Also called radioisotope laboratory.

Nuclear Suppliers Group (NSG) (Groupe des fournisseurs nucléaire (GFN))

A multilateral export control regime of nuclear supplier countries which seeks to contribute to the non-proliferation of nuclear weapons through the implementation of International Atomic Energy Agency Guidelines (INFCIRC/254, Communications Received from Certain Member States Regarding Guidelines for the Export of Nuclear Material, Equipment or Technology [6]) for supply of nuclear and nuclear-related dual-use items.

nucleus (noyau)

The very dense region at the centre of an atom that consists of protons and neutrons.

nuisance actors (personnes nuisent)

With respect to emergency preparedness, any group of individuals, from the curious to the malevolent, whose presence outside the protected zone may interfere with emergency response activities.

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