Language selection


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

HAC (conditions d’accident hypothétique)

hypothetical accident conditions

half‑life (période radioactive)

For a radionuclide, the time required for the activity to decrease, by a radioactive decay process, by half. Note: Half‑lives vary from a fraction of a second to billions of years. For example, the half‑lives of cobalt‑60 and of iridium‑192 are 5.3 years and 74.2 days, respectively.

half‑value layer (HVL) (couche de demi‑atténuation [CDA])

The thickness of a shield or absorber (such as uranium, tungsten or lead) that reduces the amount of radiation to one half of its initial intensity. Also called half‑value thickness.

half‑value thickness (HVT) (épaisseur de demi‑atténuation)

See half‑value layer.

handheld tool (outils portatifs)

A portable tool. Some handheld tools, in the context of nuclear security, may be used by an adversary to penetrate a security system or barrier. Some examples of handheld tools are bolt cutters, pliers or hacksaw blades, power tools, burn bars and cutting torches.

hazard analysis (analyse des dangers)

The process used to systematically identify and assess hazards to evaluate the potential internal, external, human-made and natural events that can cause the identified hazards to initiate faults that develop into accidents.

hazardous substance (substance dangereuse)

A substance, other than a nuclear substance, that is used or produced in the course of carrying on a licensed activity and that may pose a risk to the environment or the health and safety of persons. (Sources: Class II Nuclear Facilities and Prescribed Equipment Regulations; Uranium Mines and Mills Regulations)

hazardous substance or hazardous waste (substance dangereuse ou déchet dangereux)

A substance or waste, other than a nuclear substance, that is used or produced in the course of carrying on a licensed activity and that may pose a risk to the environment or the health and safety of persons. (Sources: General Nuclear Safety and Control Regulations; Class I Nuclear Facilities Regulations)

HCLPF (faible probabilité de défaillance avec niveau de confiance élevé [HCLPF])

high confidence of low probability of failure


See high dose rate (HDR) brachytherapy remote afterloader.

head leakage (fuite de la tête de source)

All radiation coming from within teletherapy source housing or accelerator target housing, other than the primary beam.

heat sink (source froide)

A system or component that provides a path for heat transfer from a source, such as heat generated in the fuel, to a large heat-absorbing medium, such as water. See also ultimate heat sink.

heat transport system (HTS) (circuit caloporteur)

See primary heat transport system.

heatup rate (taux de chauffe)

The rate at which the temperature of an object increases when heated.


See high-enriched uranium.


See highly enriched uranyl nitrate liquid.


See human factors.


human factors engineering; see human factors in design

high dose rate (HDR) brachytherapy remote afterloader (appareil de curiethérapie à projecteur de source télécommandé à débit de dose élevé)

A brachytherapy machine that uses a sealed source activity that, if exposed, will produce a dose rate in air of 10 milligrays per hour or greater at a distance of 1 metre from the source(s).

high‑enriched uranium (HEU) (uranium hautement enrichi [UHE])

Uranium containing 20 percent or more by weight of isotope uranium‑235, isotope uranium‑233, or combined uranium‑233 and uranium‑235. Also called highly enriched uranium.

highly enriched uranyl nitrate liquid (HEUNL) (nitrate d’uranyle liquide hautement enrichi [NULHE])

Liquid containing high‑enriched uranium.

high-power reactor facilities (installations dotées de réacteurs de haute puissance)

Power production and research reactors greater than 10 MWt.

hold point (point d’arrêt)

A commissioning activity that requires approval of the designated authority in order for commissioning to proceed.

high‑security site (site à sécurité élevée)

A nuclear power plant or a nuclear facility where Category I or II nuclear material is processed, used or stored. (Source: Nuclear Security Regulations)

hold point (point d’arrêt)

An activity that requires approval of the Commission or designated authority before the activity may proceed.

holding account (compte de dépôt)

A holding area at an identified foreign facility to which unallocated Canadian-origin nuclear material can be exported and temporarily held pending the conclusion of a commercial arrangement for nuclear material held in the account.


human and organizational performance

house load operation (fonctionnement en îlotage)

Operation of a nuclear facility that is isolated from the grid and is supplying power only to its own auxiliary electric loads. Also called island load; island operation.


See equivalent dose.


hydrogenated tritium oxide; also called tritiated water


See primary heat transport system.

human error (erreur humaine)

Inappropriate or inadequate human action, including failure to take action when required, which can arise from problems in sequencing, timing, knowledge, interfaces, procedures and other sources.

human factors (HF) (facteurs humains [FH])

Factors that influence human performance as it relates to the safety of a nuclear facility or activities over all phases, including design, construction, commissioning, operation, maintenance and decommissioning. Some examples are organizational and management structures; policies and programs; allocation of functions to humans and machines; the design of user interfaces; staffing provisions; job-design features; work schedules; design of procedures; training; and the physical work environment.

human factors engineering (HFE) (ingénierie des facteurs humains)

See human factors in design.

human factors in design (facteurs humains dans la conception)

The application of knowledge about human capabilities and limitations to a plant, facility, system or equipment design. Human factors in design ensure that the plant, facility, system or equipment design, human tasks and work environment, are compatible with the sensory, perceptual, cognitive and physical attributes of the personnel who operate, maintain and support it. Also called human factors engineering.

human performance (performance humaine)

The outcomes of human behaviours, functions and actions, in a specified environment, that reflect the ability of workers and management to meet a system’s defined performance under the conditions in which the system will be employed.

human performance management SCA (DSR Gestion de la performance humaine)

A safety and control area (SCA) that covers activities that enable effective human performance through the development and implementation of processes that ensure a sufficient number of licensee personnel are in all relevant job areas and have the necessary knowledge, skills, procedures and tools in place to safely carry out their duties. This SCA is one of the 14 within the CNSC SCA Framework.

human research study (étude sur des êtres humains)

The administration of unsealed sources (nuclear substances) to, or external irradiation of, humans for purposes not related to their personal healthcare; includes processing of radiopharmaceuticals and laboratory studies that are part of the human research study.


See half‑value layer.


half‑value thickness; see half‑value layer

H/X (H/X)

hydrogen-to-fissile atomic ratio

Page details

Date modified: