Quick Links

Appendix N

Appendix N

Glossary

Action Level
A specific dose of radiation or other parameter that, if reached, may indicate a loss of control of part of a licensee's radiation protection program and triggers a requirement for specific action to be taken.

Activation
The process of inducing radioactivity by irradiation; for example, absorption of neutrons by a stable isotope to give a radioactive isotope of the same atomic number but higher mass number.

Activity
Rate at which atoms are disintegrating. Strictly, the number of nuclear transformations in a given quantity of material per unit time.

Activity Concentration
Activity per unit volume (or mass).

ALARA
As Low As Reasonably Achievable. All doses must be kept below dose limits and as low as achievable, economic and social factors being taken into account.

Alpha-rays
Radiation consisting of 4He nuclei ejected from atomic nuclei during radioactive decay (alpha-decay).

Annihilation
Occurs when a particle and anti-particle meet. For the positron and electron, the result is two photons at 0.511 Mev.

Annual Limit of Intake
The annual limit of intake (ALI) corresponds to the activity in Becquerel of a radionuclide that, when taken into the body (by inhalation and/or ingestion), will deliver an effective dose of 20 milliSievert over the next 50 years. One ALI corresponds to the handling in a single instance of the following amounts of the listed isotopes.

Atomic Number
Number of protons in the nucleus of an atom. Defines the chemical identity of the atom.

Becquerel
S.I. Unit of Activity = 1 disintegration per second.

Beta-rays
Radiation consisting of free electrons ejected from atoms by radioactive decay (beta-decay).

Bremsstrahlung
Photon radiation produced by charged particles subject to rapid deceleration. Most often seen with electrons, producing X-rays.

Collective Dose Equivalent
The sum of the individual dose equivalents for the members of the population. Sometimes taken as a measure of the detrimental effect of low doses of radiation upon a population. Usual unit is man/rem. (S.I. unit not defined — could be man.Sv, person.Sv or just Sv).

Compton Scattering
Interaction between a photon (gamma-ray) and an electron in which part of the photon energy is transferred to the electron and the rest forms a new photon of lower energy travelling in a different direction.

Cosmic Rays
Very energetic radiations received from outer space, part of the natural radiation background.

Curie
Old unit of activity = 3.7 X 1010 disintegrations per second.

Decommission
A thorough decontamination procedure and removal of nuclear substances, certifying that the area or laboratory is free from radioactivity or radioactive surface contamination.

Delta-rays
Short range secondary electrons produced along the track of a primary ionising particle.

Deuterium
Special name for 2H, often given the chemical symbol, D.

Device
For the purposes of this guide and the application form, a device is any piece of equipment designed to use a sealed source(s) with the sealed source(s) installed and for which a Device Certification has been issued by the CNSC.

Diagnostic Nuclear Medicine
Administration of unsealed nuclear substances to humans for diagnostic purposes related to their health care; processing of radio pharmaceuticals and laboratory studies which are part of the diagnostic studies are included.

Dismantle
To take apart prescribed equipment for the purpose of repairing, replacing, removing faulty components, which may include the nuclear substance of that device (part of the licensed activity of servicing, installation and dismantling of devices containing radioisotopes). Dose
A measure of the amount of radiation absorbed per unit mass of material (often tissue).
Old unit: rad = 100 erg/g
S.I. unit: gray = J/kg = 100 rad.

Effective Dose
The weighted average of the dose equivalent over the major organs of the body using published tables of weighting factors for the different organs (see ICRP report #60). It is the dosimetric quantity that is intended to reflect the risk of long-term effects from low doses of radiation for use in cases of non-uniform exposure. See Manual section 3.7.

Electron
A stable elementary particle associated with negative electrical charge, with the passage of electrical currents and with the chemical activity of atoms.

Electron Capture
Radioactive decay mode in which one of the orbital electrons of an atoms is absorbed by the nucleus, reducing the atomic number by 1. Usually results in the emission of characteristic X-rays.

Electron Volt (eV)
The kinetic energy acquired by an electron in passing through a potential difference of 1 volt in vacuum. 1 eV = 1.6 X 10-19 J (approx.)

Equivalent Dose
The radiation dose weighted to account for the different biological effectiveness of radiations = Dose X Quality Factor. Old unit: rem (dose in rads) S.I. unit: Sievert (dose in Gy). See Appendix B.

Excited State
Temporary state of a nucleus, atom or molecule intermediate in potential energy between the normal stable state and compete disintegration, ionisation or decomposition respectively

Exemption Quantity
A quantity of a radioactive nuclear substance as defined Nuclear Substances and Radiation Devices Regulations.

Export
To send a nuclear substance or prescribed equipment out of Canada.

Exposure
A measure of the amount of ionising radiation present. See Roentgen.

Fission
Splitting of an atomic nucleus into two or more lighter nuclei (fission products). Can either be spontaneous or induced (by neutron capture).

Five-Year Dosimetry Period
The period of five calendar years beginning on January 1 of the year following the year in which the CNSC Regulations come into force, and every period of five years thereafter.

Flux
Number of particles crossing a unit area, or Flux Rate the number crossing unit area in unit time. The units used distinguish the two cases.

Gamma Radiation
High energy electromagnetic (photon) radiation emitted by an atomic nucleus.

Gamma Ray Constant
Empirical quantity (K) that allows one to predict the exposure rate at a distance from a source of activity A. Exposure = AK/d2. If exposure is measured in R/h, activity in Curies and d in metres the K = 0.6 X E (approx.) where E is the total gamma ray energy per disintegration in Mev.

Gray (Gy)
S.I. unit of radiation dose = J/kg.

Half-life
Time for the activity of an isotopically pure radioactive source to fall to half its initial value.

Half Value Layer
Thickness of material required to halve the intensity of X- or gamma-ray beam.

Heavy Water
Deuterium oxide, D2O = 2H2O

Human Research Studies
Administration of unsealed nuclear substances to or external irradiation of humans for purposes not related to their personal health care; processing of radio pharmaceuticals and laboratory studies which are part of the human research study are included.

ICRP, ICRU
International committees concerned with recommending practices in radiation protection. See Bibliography.

Internal Conversion
Atomic process whereby a nucleus in an excited state decays to its stable state by transferring the excess energy to one of the orbital electrons of the atom. Usually results in the emission of characteristic X-rays as well as the conversion electron.

Import
To bring a nuclear substance or prescribed equipment into Canada.

Internal Conversion
Atomic process whereby a nucleus in an excited state decays to its stable state by transferring the excess energy to one of the orbital electrons of the atom. Usually results in the emission of characteristic X-rays as well as the conversion electron.

Ion, Ionisation
An ion is an atom or molecule with more (negative ion) or less (positive ion) electrons than needed for electric neutrality. The process of creating ions is ionisation.

Isotopes
Atomic species (nuclides) with the same atomic number (chemical identity) and differing mass numbers. The singular, isotope, is also used as an equivalent of nuclide (q.v.).

LET
Linear Energy Transfer = density of ionisation along the track of radiation.

Licensed Activity

For the purpose of this licensing guide an activity, in relation to a nuclear substance or a radiation device described below, that a licence authorises the licensee to:
(a) possess, transfer, import, export, use or abandon a nuclear substance, prescribed equipment or prescribed information;
(b) mine, produce, refine, convert, enrich, process, reprocess, package, transport, manage, store or dispose of a nuclear substance; or
(c) produce or service prescribed equipment.

Licensed Use Type
A particular use of nuclear substances as described in the Cost Recovery Fees Regulations.

Location
Any land, base(s) of operations, or premises the licensee occupies, where the licensee uses or stores nuclear substances for more than 90 consecutive days.

M-Isomer
Long-lived excited state of an atomic nucleus. Usually decays to the normal (ground) state by emission of a gamma-ray.

Man.rem
Commonly used unit for Collective Dose Equivalent (q.v.).

Mass Number
Total number of nucleons (protons and neutrons) in the nucleus of an atom.

Maximum Specific Activity
Specific activity of pure isotope in elemental form = gammaNBq/mol, where

gamma = .693/T1/2 (S-1)
N = 6 X 1023 mol-1
T1/2 = half life (q.v.)

Meson
General term for particles with a mass intermediate between an electron and a proton or neutron. Produced by accelerators and cosmic rays.

Nuclear Energy Worker (NEW)
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.

Nuclear Substance
(a) deuterium, thorium, uranium or an element with an atomic number greater than 92;
(b) a derivative or compound of deuterium, thorium, uranium or of an element with an atomic number greater than 92;
(c) a radioactive nuclide;
(d) a substance that is prescribed as being capable of releasing nuclear energy or as being required for the production or use of nuclear energy;
(e) a radioactive by-product of the development, production or use of nuclear energy; and
(f) a Radioactive substance or radioactive thing that was used for the development or production, or in connection with the use, of nuclear energy.

Nucleus
Central volume of an atom, consisting of protons and neutrons and accounting for most of the atomic mass.

Nuclide
A particular atomic species distinguished by both its atomic number and mass number.

Neutrino
Light unchanged particle emitted during alpha-decay.

Neutron
One of three elementary particles, which is part of all nuclei heavier than hydrogen.

One-year Dosimetry Period
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 thereafter.

Package
To put a nuclear substance or prescribed equipment into a form of containment for purposes of transport.

Pair Production
The reverse of annihilation. An interaction between a gamma-ray and an atomic nucleus in which 1.022 MeV of the photon energy is used to form an electrons-positions pair.

Photo-electron
Produced when an electron totally absorbs a high energy photon (gamma-ray) and acquires sufficient energy to escape from its atoms.

Photon
Particle of electromagnetic radiation.

Planck's Law
E = hf
where E = energy of photon; f = frequency of electromagnetic radiation; and h = Planck's constant = 4.14 X 10-15 v.s.

Positron
Light positively charged particle, anti-particle of the electron, emitted during beta-decay.

Possess
To have the care and control of a nuclear substance or prescribed equipment.

Proton
Elementary particle, part of the mass of an atomic nucleus, associated with the positive electrical charge.

Quality Factor
Nominal biological effectiveness of radiation as set by regulatory bodies. Value is 1 for beta, gamma and X-rays; 20 for alpha; depends on energy for neutrons.

Rad
Old unit of radiation dose = 100 erg/gram.

Radiation Device
(a) 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
(b) a device that contains a radium luminous compound.

Radiation Survey Metre
An instrument that is capable of measuring radiation dose rates (mrem/h or mSv/h).

Relative Biological Effectiveness (RBE)
Ratio of the doses of different radiations required to give the same biological effect. Reference radiation is usually X-rays or gamma-rays.

Rem
Old unit of Dose Equivalent

Roentgen
Unit of exposure; that quantity of X- or gamma-radiation that results in the production of 1 e.s.u. of charge in 1 cm3 of air at S.T.P. = 258 mC/kg air (S.I. definition).

Sealed Source
A radioactive nuclear substance in a sealed capsule or in a cover to which the substance is bonded, where the capsule or cover is strong enough to prevent contact with or the dispersion of the substance under the conditions for which the capsule or cover is designed.

S.I.
Système International. Internationally-agreed system of metric units.

Sievert (Sv)
S.I. unit of dose equivalent.

Source in Device
A sealed source which remains in a device giving mechanical protection from damage during use

Specific Activity
Ratio of radioactive atoms (or molecules) to total of chemically similar atoms (or molecules) [Ci/mole or Bq/mol).

Store
To lay away for future purposes.

Therapeutic Nuclear Medicine
Administration of unsealed nuclear substances to humans for therapeutic purposes related to their health care; processing of radio pharmaceuticals and laboratory studies which are part of the therapy are included.

Transfer
To change the possession of a nuclear substance or prescribed equipment from one person to another.

Transport
To handle, carry, store in transit and receive goods at the final destination. Transport includes normal and accident conditions encountered in carriage and in storage during transit.

Tritium
Special name for 3H, often given the chemical symbol T.

Ultra-violet
Electromagnetic radiation more energetic (higher frequency) than visible light but insufficiently energetic to cause ionisation.

Unsealed Source
A source other than a sealed source.

Use
To put into operation.

Worker
A person who performs an activity that is referred to in the licence.

Working Level
A special unit to describe the activities of the short-lived daughters of radon in air. Defined as any combination that results in emission of 1.3 X 105 MeV/L of alpha energy in decaying to lead-210.

X-rays
High energy electromagnetic (photon) radiation emitted by electrons: -when changing energy levels within an atom (characteristic or fluorescence X-rays) -when rapidly decelerated, usually by hitting a solid target (conventional X-ray set — Brensstrahlung).