RPS G-2 - Glossary

Accident

Any unintended event, including operating errors, equipment failures and other mishaps, the consequences or potential consequences of which are not negligible from the point of view of protection and safety. 

Authorisation 

The granting by a relevant regulatory body of written permission for a Responsible Person to conduct specified activities. 

Biota

See wildlife

Contamination

Radioactive substances on surfaces or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable, or the process giving rise to their presence in such places.

Cosmic radiation

See source

Derived reference level

Numerical value expressed in an operational or measurable quantity, corresponding to the reference level set in dose.

Dose 

  1. A measure of the energy deposited by radiation in a target.
  2. Absorbed dose, committed dose (i.e. committed equivalent dose or committed effective dose), effective dose, equivalent dose or organ dose, as indicated by the context.

Dose limit

The value of a quantity used in certain specified activities or circumstances that must not be exceeded.

Effective dose, E

The quantity E, defined as a summation of the tissue or organ equivalent doses, each multiplied by the appropriate tissue weighting factor:

Effective dose equation 1 weighting factor

where:

HT is the equivalent dose in tissue or organ T, and

wT is the tissue weighting factor for a tissue or organ T

From the definition of equivalent dose, it follows that:

Equivalent dose equation 2 definition RPS G-2

where

wR is the radiation weighting factor for radiation type R, and

DT,R is the average absorbed dose in the tissue or organ T delivered by radiation type R.

The SI unit for effective dose is joule per kilogram (J kg-1), termed the sievert (Sv). An explanation of the quantity is given in Annex B of the ICRP Publication 103 (ICRP 2007).

Effective dose is a measure of dose designed to reflect the amount of radiation detriment likely to result from the dose.

Effective dose cannot be used to quantify higher doses or to make decisions on the need for any medical treatment relating to tissue reactions effects.

Values of effective dose from exposure for any type(s) of radiation and any mode(s) of exposure can be compared directly.

Emergency exposure situation

A situation of exposure that arises as a result of an accident, a malicious act, or any other unexpected event, and requires prompt action in order to avoid or reduce adverse consequences.

Emergency

A non-routine situation that necessitates prompt action, primarily to mitigate a hazard or adverse consequences for human health and safety, quality of life, property or the environment. This includes nuclear or radiological emergencies and conventional emergencies such as fires, release of hazardous chemicals, storms or earthquakes. It includes situations for which prompt action is warranted to mitigate the effects of a perceived hazard.

Exposure pathway

A route by which radiation or radionuclides can reach humans and cause exposure. 

Nuclear or radiological emergency 

An emergency in which there is, or is perceived to be, a hazard due to:

  1. the energy resulting from a nuclear chain reaction or from the decay of the products of a chain reaction, or
  2. radiation exposure.

Environment

The conditions under which people, animals and plants live or develop and which sustain all life and development, especially such conditions as affected by human activities. Protection of the environment includes the protection and conservation of:  

  • non-human species, both animal and plant, and their biodiversity
  • environmental goods and services such as the production of food and feed
  • resources used in agriculture, forestry, fisheries and tourism
  • amenities used in spiritual, cultural and recreational activities
  • media such as soil, water and air
  • natural processes such as carbon, nitrogen and water cycles.

Environmental exposure

The exposure of animals, plants and other organisms in the natural environment.

Equivalent dose 

Equivalent dose equation 1

where

DT,R is the absorbed dose delivered by radiation type R averaged over a tissue or organ T, and 
wR is the radiation weighting factor for radiation type R.

When the radiation field is composed of different radiation types with different values of wR, the equivalent dose is:

Equivalent dose equation 2 RPS G-2

The SI unit for equivalent dose is joule per kilogram (J kg-1), termed the sievert (Sv). An explanation of the quantity is given in Annex B of the ICRP Publication 103 (ICRP 2007).

Equivalent dose is a measure of the dose to a tissue or organ designed to reflect the amount of harm caused.

Equivalent dose cannot be used to quantify higher doses or to make decisions on the need for any medical treatment relating to tissue reactions effects.

Values of equivalent dose to a specified tissue or organ from any type(s) of radiation can be compared directly.

Existing exposure situation

A situation of exposure that already exists when a decision on the need for control needs to be taken. Existing exposure situations include exposure to natural background radiation that is amenable to control, exposure due to residual radioactive material that derives from past practices that were never subject to regulatory control, and exposure due to residual radioactive material deriving from a nuclear or radiological emergency after an emergency has been declared to be ended.

Exposure 

The state or condition of being subjected to radiation. External exposure is exposure to radiation from a source outside the body. Internal exposure is exposure to radiation from a source within the body.

Graded approach

For a system of control, such as a regulatory system or a safety system, a process or method in which the stringency of the control measures and conditions to be applied is commensurate, to the extent practicable, with the likelihood and possible consequences of, and the level of risk associated with, a loss of control.

Incident 

Any unintended event, including operating errors, equipment failures, initiating events, accident precursors, near misses or other mishaps, or unauthorised act, malicious or non-malicious, the consequences or potential consequences of which are not negligible from the point of view of protection and safety. 

Ionising radiation 

For the purposes of radiation protection, radiation capable of producing ion pairs in biological material(s).

Justified 

See ‘Justification

Justification

For a planned exposure situation, the process of determining whether a practice is beneficial overall, i.e. whether the expected benefits to individuals and to society from introducing or continuing the practice outweigh the harm (including radiation detriment) resulting from the practice.

Medical exposure 

Exposure incurred by patients as part of their own medical or dental diagnosis (diagnostic exposure) or treatment (therapeutic exposure) by persons, other than those occupationally exposed, knowingly, while voluntarily helping in the support and comfort of patients, and by volunteers in a program of biomedical research involving their exposure.

Natural background

The doses, dose rates or activity concentrations associated with natural sources, or any other sources in the environment that are not amenable to control.

Natural Occurring Radioactive Material (NORM)

Radioactive material containing no significant amounts of radionuclides other than naturally-occurring radionuclides. 

Nuclear or radiological emergency

See 'emergency'.

Occupancy factor

A typical fraction of the time for which a location is occupied by an individual or group.

Occupational exposure 

Exposure of workers incurred in the course of their work. 

Occupationally exposed person

A worker who is exposed to ionising radiation arising from work undertaken within a practice. 

Optimisation 

For existing exposure situations, optimisation of protection and safety is the process of determining what level of protection and safety would result in the magnitude of individual doses, the number of individuals (workers and members of the public) subject to exposure and the likelihood of exposure being ‘as low as reasonably achievable, economic and societal factors being taken into account’ (ALARA). 

Optimised 

See ‘Optimisation’. 

Planned exposure situation

The situation of exposure that arises from the planned operation of a source or from a planned activity that results in an exposure due to a source. Since provision for protection and safety can be made before embarking on the activity concerned, associated

exposures and their probabilities of occurrence can be restricted from the outset. The primary means of controlling exposure in planned exposure situations is by good design of installations, equipment and operating procedures. In planned exposure situations, a certain level of exposure is expected to occur. 

Practice 

Any human activity that introduces additional sources of radiation or additional exposure pathways, or that modifies the network of exposure pathways from existing sources, so as to increase the exposure or the likelihood of exposure of people or the number of people exposed. 

Protection and safety

The protection of people against exposure to ionising radiation or exposure due to radioactive material and the safety of sources, including the means for achieving this, and the means for preventing accidents and for mitigating the consequences of accidents if they do occur. 

For the purposes of this Guide, ‘protection and safety’ includes the protection of people against ionising radiation and safety. It does not include non-radiation-related aspects of safety. ‘Protection and safety’ is concerned with both radiation risks under normal circumstances and radiation risks as a consequence of incidents, as well as with other possible direct consequences of a loss of control over a nuclear reactor core, nuclear chain reaction, radioactive source or any other source of radiation. Safety measures include actions to prevent incidents and arrangements put in place to mitigate their consequences if they were to occur.

Protective actions

A response action for the purposes of avoiding or reducing doses that might otherwise be received in an existing exposure situation.

Protective measures

Reasonably measures to be taken to reduce radiation exposures to the public, wildlife and workers using remedial actions and or protective actions to adverse conditions.

Public exposure 

Exposure incurred by members of the public due to sources in planned exposure situations, emergency exposure situations and existing exposure situations, excluding any occupational exposure or medical exposure.

Radiation 

In this Guide, the term ‘radiation’ refers only to ionising radiation unless otherwise stated. For the purposes of radiation protection, ionising radiation is capable of producing ion pairs in biological material(s).

For most practical purposes, it may be assumed that weakly penetrating radiation includes photons of energy below about 12 keV, electrons of energy less than about 2 MeV, and massive charged particles such as protons and alpha particles.

Radiation protection 

The protection of people and the environment from harmful effects of exposure to ionising radiation, and the means for achieving this.

Radiation risk

Detrimental health effects of exposure to ionising radiation including the likelihood of such effects occurring, and other risks including environmental risks, that might arise from exposure to ionising radiation; the presence of radioactive material (including radioactive waste) or its release to the environment; or a loss of control over a nuclear reactor core, nuclear chain reaction, radioactive source or any other source of radiation; alone or in combination.

Radioactive material 

Scientific meaning: Material exhibiting radioactivity, emitting or relating to the emission of ionising radiation or particles.

Legal meaning: Material designated by the relevant regulatory body as being subject to regulatory control because of its radioactivity. 

Radionuclides of natural origin

Radionuclides that occur naturally on Earth in significant quantities.

The term is usually used to refer to the primordial radionuclides 40K, 235U, 238U, 232Th and their radioactive decay products.

Contrasted with radionuclides of artificial origin; artificial radionuclides, anthropogenic radionuclides and human-made radionuclides.

Radioactive waste

For legal and regulatory purposes, material for which no further use is foreseen that contains, or is contaminated with, radionuclides at activity concentrations greater than clearance levels (refer to RPS C-1 for more information on the clearance process) as established by the regulatory body.

Radon

Any combination of isotopes of the element radon.

For the purposes of this Guide, radon refers to 220Rn and 222Rn.

Radon progeny

The short-lived radioactive decay products of 220Rn and of 222Rn.

For 222Rn, this includes the decay chain up to but not including 210Pb, namely 218Po, 214Pb, 214Bi and 214Po, plus traces of 218At, 210Tl and 209Pb. 210Pb, which has a half-life of 22.3 y, and its radioactive progeny — 210Bi and 210Po, plus traces of 206Hg and 206Tl — are, strictly, progeny of 222Rn, but they are not included in this listing because they will not normally be present in significant amounts in airborne form. For 220Rn, this includes 216Po, 212Pb, 212Bi, 212Po and 208Tl.

Reference level

For an emergency exposure situation or an existing exposure situation, the level of dose, risk or activity concentration above which it is not appropriate to plan to allow exposures to occur and below which optimisation of protection and safety would continue to be implemented.

Regulatory body

An authority or a system of authorities designated by the government as having legal authority for conducting the regulatory process, including issuing authorisations, and thereby regulating nuclear, radiation, radioactive waste and transport safety. A list of relevant radiation regulatory authorities in Australia can be found on ARPANSA’s website at www.arpansa.gov.au/regulation-and-licensing/regulation/state-territory-regulators.

Remedial action

The removal of a source or the reduction of its magnitude (in terms of activity or amount) for the purposes of preventing or reducing exposures that might otherwise occur in an existing exposure situation.

Remedial actions could also be termed longer term protective action, but longer term protective actions are not necessarily remedial actions.

Remediation

Any measures that may be carried out to reduce the radiation exposure due to existing contamination of land areas through actions applied to the contamination itself (the source) or to the exposure pathways to humans and the environment.

Representative person 

An individual receiving a dose that is representative of the more highly exposed individuals in the population (see Publication 101a, ICRP 2006). 

Residual radioactive material 

Residual radioactive material is radioactive material that remains in the environment following some past practice including a past remediation. 

Safety

For the purposes of this Guide, ‘safety’ means the protection of people and the environment against radiation risks, and the safety of facilities and activities that give rise to radiation risks. ‘Safety’ as used here includes the safety of nuclear installations, radiation safety, the safety of radioactive waste management and safety in the transport of radioactive material. It does not include non-radiation related aspects of safety.

Safety is concerned with both radiation risks under normal circumstances and radiation risks as a consequence of incidents, as well as with other possible direct consequences of a loss of control over a nuclear reactor core, nuclear chain reaction, radioactive source or any other source of radiation. Safety measures include actions to prevent incidents and arrangements put in place to mitigate their consequences if they were to occur.

Safety assessment

Assessment of all aspects of a practice that are relevant to protection and safety. For an authorised facility, this includes siting, design and operation of the facility.

Soil amendments

Soil amendments are materials which are worked into the soil to enhance the soil’s physical properties. Soil amendments are any material such as lime, gypsum, sawdust, compost, animal manures, crop residue or synthetic soil conditioners that is worked into the soil or applied on the surface to enhance plant growth. Amendments may contain important fertiliser elements but the term commonly refers to added materials other than those used primarily as fertilisers.

Source

1. Anything that may cause radiation exposure — such as by emitting ionising radiation or by releasing radioactive substances or radioactive material — and can be treated as a single entity for purposes of protection and safety.

Natural source. A naturally occurring source of radiation, such as the sun and stars (sources of cosmic radiation), rocks and soil (terrestrial sources of radiation), or any other material whose radioactivity is for all intents and purposes due only to radionuclides of natural origin, such as products or residues from the processing of minerals, but excluding radioactive material for use in a nuclear installation and radioactive waste generated in a nuclear installation.

2. Radioactive material used as a source of radiation.

Stochastic health effect

A radiation induced health effect, the probability of occurrence of which is greater for a higher radiation dose and the severity of which (if it occurs) is independent of dose. Stochastic effects may be somatic effects or hereditary effects, and generally occur without a threshold level of dose. Examples include solid cancers and leukaemia.

Tissue reactions

Harmful reaction to radiation in a population of cells (tissue) where a threshold dose has to be exceeded for it to be expressed in a clinically relevant form, and where the severity of harm increases with the dose. Often used as synonymous to ‘deterministic effects’. Tissue reactions is the preferred term as the effect is susceptible to a range of modifiers, i.e. is not strictly pre-determined.

Wildlife

Any wild animal or plant living within its natural environment. This excludes stock, farmed, feral or domesticated species. The objects of environmental protection and used interchangeably with non-human biota, plants and animals, and flora and fauna in this Guide.