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

obligations (obligations)

Legally binding commitments regarding nuclear material, non-nuclear material, nuclear equipment and nuclear information (sometimes referred to as “flags”). Obligations arise most commonly from the requirements of government-to-government nuclear cooperation agreements, wherein the parties to the agreements are bound to fulfill those requirements before authorizing the transfer of the obligated items.

observed reliability (fiabilité observée)

A reliability measure that is calculated using actual operating performance.

observer (observateur)

In an emergency exercise, a person who is authorized to witness the exercise but who is not a participant, controller or evaluator.

obsolescence (obsolescence)

With respect to structures, systems and components, the process of becoming out of date in comparison with current knowledge, standards and technology.


organically bound tritium

occupancy factor (facteur d’occupation)

The fraction of total time during which a radiation field is present at a particular location, for which any one individual would reasonably be expected to be present at that location. This factor (≤1) is multiplied by the total radiation dose at that location, to derive the maximum personal dose any single person would be expected to receive.

offsite (hors site)

The facilities and organizations outside the juridical consideration of the licensed facility, including the various federal, provincial and municipal organizations that are required to communicate with and respond to a facility accident in accordance with the facility accident management procedures.

offsite power (alimentation électrique hors site)

Power supplied from an electrical grid.

offsite response force (force d’intervention externe)

A local, provincial or federal police service whose members are not located at a nuclear facility. (Source: Nuclear Security Regulations)

OJT (formation en cours d’emploi [FCE] ou formation en milieu de travail)

See on-the-job training.


See operational limits and conditions.

one‑year dosimetry period (période de dosimétrie d’un an)

The period of one calendar year beginning on January 1 of the year following the year in which these Regulations come into force, and every period of one calendar year after that period. (Source: Radiation Protection Regulations)

Note: These Regulations came into force in May 2000; therefore the first dosimetry period began on January 1, 2001.

onsite (sur le site)

The physical domain of the facility to which a licence is granted.

onsite nuclear response force (force d’intervention nucléaire interne)


  1. a team of nuclear security officers whose members are
    1. trained in the use of firearms, authorized to carry firearms in Canada and qualified to use them, and
    2. permanently located at a high-security site; or
  2. a local, provincial or federal police service, a Canadian Forces unit or any other force
    1. under contract to a licensee,
    2. whose members are trained in the use of firearms, authorized to carry firearms in Canada and qualified to use them, and
    3. whose members are permanently located at a high-security site

(Source: Nuclear Security Regulations)

onsite power (alimentation électrique sur le site)

Power supplied from a nuclear power plant’s alternating current (AC) power systems, direct current (DC) power systems and uninterruptible AC power systems.

on-the-job evaluation (évaluation en cours d’emploi)

Performance demonstration by a trainee of knowledge, skills, safety-related attributes and work practice standards required to perform a task using the approved procedure and the prescribed standards. The evaluation is conducted on the job.

on-the-job training (OJT) (formation en cours d’emploi [FCE]ou formation en milieu de travail)

The training undertaken in the actual work environment to obtain required job-related knowledge and skills.


See operating policies and principles.

open source (source non scellée)

See unsealed source.

operate (faire fonctionner)

Includes, in respect of an exposure device, coupling the drive mechanism to the exposure device, uncoupling the drive mechanism from the exposure device, locking or unlocking the exposure device, and all activities involving the device that take place while the sealed source assembly is not locked inside the device in the fully shielded position. (Source: Nuclear Substances and Radiation Devices Regulations)


For other devices, equipment or facilities, operate means turning on and using the device, equipment or facility for its intended purpose and in accordance with the manufacturer’s instructions. Operate includes minor upkeep as per the operating manual.

operating experience (OPEX) (expérience d’exploitation [OPEX])

Pertinent internal and external information, gained through practical experience, used to learn about and improve the safety and reliability of nuclear facilities.

operating organization (exploitant)

The responsible organization that operates, or will operate, a facility. This organization may be the licensee, the applicant or an organization that will operate the facility on behalf of the applicant.

operating performance SCA (DSR Conduite de l’exploitation)

A safety and control area (SCA) that includes an overall review of the conduct of the licensed activities and the activities that enable effective performance. This SCA is one of the 14 within the CNSC SCA Framework.

operating policies and principles (OP&P) (lignes de conduite pour l’exploitation [LCE])

The boundaries within which a nuclear power plant must be operated, maintained and modified, to keep the risk to workers, the public and the environment acceptably low.

operating states (états de fonctionnement)

See operational states.

operation (exploitation)

All activities performed to achieve the purpose for which a nuclear facility was constructed. For example, at reactor facilities, operation includes maintenance, refuelling, in‑service inspection and other associated activities.

operational limits and conditions (OLC)(limites et conditions d’exploitation [LCE])

A set of rules setting forth parameter limits and the functional capability and performance levels of equipment and personnel for safe operation of a nuclear facility. This set of limits and conditions is monitored by or on behalf of the operator and can be controlled by the operator.

operational mode (mode d’exploitation)

In a reactor facility, a mode of operation that may include start‑up, operation at various power levels, shutting down, shutdown, maintenance, testing and refuelling.

operational parameters (paramètres d’exploitation)

See plant parameters.

operational states (états de fonctionnement)

Plant states defined under normal operation and anticipated operational occurrences.

operations with fissionable materials (activités comportant des matières fissiles)

Any activity involving the handling, use, processing, movement and storage of fissionable materials within nuclear facilities and the long‑term management of nuclear waste containing fissionable materials.

operator (exploitant)

A person who is designated by a regulation made under section 7 as an operator. (Source: Nuclear Liability and Compensation Act)


The holder of a subsisting licence issued pursuant to the Nuclear Safety and Control Act for the operation of a nuclear installation or, in relation to any nuclear installation for the operation of which there is no subsisting licence, the recipient of the licence last issued pursuant to the Nuclear Safety and Control Act for the operation of that nuclear installation.


operator (opérateur)

An industrial device operator.


A person responsible for nuclear material inventory.


See certified exposure device operator.


See reactor operator.


See unit 0 operator.


See operating experience.

oral fluid specimen collector (personne chargée du prélèvement des échantillons de sécrétions orales)

A trained person who instructs and assists workers at an oral fluid collection site, receives the specimen provided by each worker and performs an initial inspection of that specimen, and initiates and completes a custody control form for that specimen.

order (ordre)

One of the regulatory tools the CNSC uses to compel someone to do something in the interests of health, safety, the environment, national security or compliance with Canada’s international obligations. Failure to comply with an order can lead to further regulatory measures, including prosecution or licensing actions.

ore (minerai)

A mineral or chemical aggregate containing uranium in a quantity and of a quality that makes mining and extracting the uranium economically viable. (Source: Uranium Mines and Mills Regulations)

Note: Ore may also include thorium.

organically bound tritium (OBT) (tritium lié aux composés organiques [TLCO])

Tritium that is bound to an organic molecule. For dosimetry purposes, OBT is carbon-bound tritium formed in living systems through natural biological processes.

orphaned source (source orpheline)

A radioactive source that is found in the public domain, and for which no responsible owner can be established, or which is in the possession of a person who cannot be held responsible for the source’s safe storage or disposal.

other person (autre personne)

With respect to a location where licensed activity is carried out, a person who is present at the location but does not perform work referred to in the licence.

other worker (autre travailleur)

A worker who has not been designated as a nuclear energy worker and is subject to the prescribed dose limit for the general public.

overburden (morts‑terrains)

For uranium mining purposes, generally the material overlying the ore deposit, including rock as well as soil and other unconsolidated (loose) material, such as glacial deposits, sand and sediment.

overhaul (remise en état)

The comprehensive inspection and restoration of a structure, system or component to maintain it in good operating condition or to restore its ability to function as per design. Overhaul includes such actions as disassembly, cleaning, lubrication, adjustments, parts inspection or replacement, and testing.

overpack (suremballage)

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

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