DEFINITIONS OF TERMS USED IN PROTECTION AGAINST IONISING RADIATION
The terms “radioactive substance”, “radioactive material” and “radioactive waste” are defined in article L. 542-1-1 of the French Environment Code.
Accelerator: equipment or installation in which particles are subjected to acceleration, emitting ionising radiation with an energy greater than one mega-electronvolt (MeV).
Malicious act: theft, misappropriation, deliberate deterioration of a source of ionising radiation or any other act intended to intentionally cause risks or inconveniences for the interests mentioned in article L. 1333-7.
Activation: a process by which a stable nuclide is transformed into a radionuclide by irradiating the substance containing it with high-energy particles or photons;
Activity (A): the activity A of a quantity of a radionuclide in a given energy state and at a given time is the quotient of dN by dt, where dN is the probable number of spontaneous nuclear transitions with the emission of ionising radiation from this energy state in the time interval dt.
A = dN/ dt
The unit of activity of a radioactive source is the becquerel (Bq).
Becquerel (Bq): name of the unit of activity. One becquerel is equivalent to one nuclear transition per second.
Category of nuclear activities: a group of nuclear activities using similar techniques for the same purpose and presenting an equivalent level of risk.
Category of a source of ionising radiation: the intrinsic level of danger posed by a source of ionising radiation. A source is classified in category A, B, C or D as follows:
-Category C if it is a high activity sealed source whose activity is less than the activity level defined in the sixth column of table 2 of appendix 13-8 of part one of this code;
Category B in the case of a high-activity sealed source whose activity is less than the activity level defined in the seventh column of Table 2 of Annex 13-8 to Part I of this Code and which meets at least one of the following two conditions: the activity is greater than or equal to the activity level defined in the sixth column of the same table or the source is contained in a portable or mobile device;
-Category A in other cases if it is a high activity sealed source;
-Category D in all other cases.
Ionising radiation sources meeting the exemption conditions mentioned in article R. 1333-106 are not categorised.
Transfer of an ionising radiation source: any change in the holder of an ionising radiation source, whether temporary or permanent, involving a transfer of custody of the said source for any purpose whatsoever.
Dose constraint: a restriction defined prospectively in terms of individual dose, used to define the options considered in the optimisation process when carrying out a nuclear activity.
Defaulting party: a person responsible for a nuclear activity who is or has been the subject of compulsory liquidation and who, as a result, is unable to fulfil his or her obligations in terms of the return or take-back of sealed radioactive sources, the management of radioactive waste or the management of sites polluted by radioactive substances resulting from the exercise of his or her activity.
Holding ionising radiation sources: temporary or permanent custody of ionising radiation sources for any purpose whatsoever, including warehousing and storage, with the exception of the custody of sites polluted by radioactive substances and the transport of radioactive substances.
Distribution of sources of ionising radiation: action of transferring a source of ionising radiation, temporarily or permanently, whether in return for payment or free of charge, with the exception of transfers between users, the return of sealed radioactive sources to a supplier at the end of their useful life and the transfer of sites polluted by radioactive substances.
Absorbed dose (D): energy absorbed per unit mass:
D = dE/ dm
where
-dE is the average energy imparted by ionising radiation to matter in a volume element ;
-dm is the mass of the material contained in this volume element.
The term “absorbed dose” refers to the average dose received by a tissue or organ. The unit of absorbed dose is the gray (Gy).
Effective dose (E): sum of the weighted equivalent doses delivered to the various tissues and organs of the body as a result of internal and external exposure. It is defined by the formula :
E = Sum wTHT = Sum wT Sum wRDT, R
where :
-DT, R is the average absorbed dose of radiation R for organ or tissue T ;
-wR is the weighting factor for radiation R ;
-wT is the weighting factor for the tissue or organ T.
The appropriate values for wT and wR are set in the order referred to in Article R. 1333-24. The unit of effective dose is the sievert (Sv).
Committed effective dose [E (t)]: sum of the equivalent doses committed to the various tissues or organs [HT (t)] following an intake, each multiplied by the appropriate tissue weighting factor wT. It is given by the formula :
E (t) = Sum of wTHT (t)
The unit of effective dose is the sievert (Sv).
Equivalent dose (HT): dose absorbed by the tissue or organ T, weighted according to the type and energy of the radiation R. It is given by the formula:
HT, R = wR DT, R
where :
-DT, R is the average absorbed dose of radiation R for the organ or tissue T ;
-wR is the weighting factor for radiation R.
When the radiation field includes radiations of types and energies corresponding to different values of wR, the total equivalent dose HT is given by the formula :
HT = Sum wRDT, R
The appropriate values of wR are set in the order referred to in Article R. 1333-24. The unit of equivalent dose is the sievert (Sv).
Committed equivalent dose [HT (t)]: integral over time (t) of the equivalent dose rate to tissue or organ T that will be received by an individual following an intake. For an intake of activity at time t0, it is defined by the formula :
HT (t) = Integral HT (t) dt
where :
-HT (t) is the equivalent dose rate to organ or tissue T at time t ;
-t is the period over which the integration is performed.
In HT (t), t is given in years. If the value of t is not given, it is implicitly, for adults, 50 years and, for children, the number of years between the age at incorporation and the age of 70. The unit of equivalent dose is the sievert (Sv).
Exposure: the act of being exposed to ionising radiation.
Terms used:
-External exposure: exposure resulting from ionising radiation sources outside the body;
-Internal exposure: exposure resulting from sources of ionising radiation inside the body;
-Total exposure: sum of external and internal exposure;
-Overall exposure: exposure of the whole body considered as homogeneous;
-Partial exposure: exposure mainly affecting one part of the body or one or more organs or tissues.
Manufacture: any operation aimed at manufacturing or producing a source of ionising radiation.
Supplier: any person involved in the distribution of ionising radiation sources.
Gray (unit of absorbed dose): one gray (Gy) corresponds to one joule per kilogram (1 Gy = 1 J. kg-1).
Incorporation: total activity of a radionuclide entering the body from the surrounding environment.
Dose limits: maximum reference values for doses resulting from exposure to ionising radiation of workers, pregnant or breast-feeding women, apprentices and students, as well as other persons mentioned in article R. 1333-11 and which apply to the sum of the doses concerned resulting from external sources of ionising radiation during the specified period and the committed doses resulting from incorporation during the same period.
Batch of radioactive sources: a set of sealed radioactive sources contained in the same product or device or which are protected against malicious acts only by common means and whose ratio :
You can consult the full text with its images from the authenticated electronic extract of the Official Journal accessible at the following address https :// www. legifrance. gouv. fr/ jo _ pdf. do ? id = JORFTEXT000036984723
is greater than or equal to 1,
where
-n is the number of different radionuclides contained in the sources in the batch ;
-i is the number of sources in the batch containing radionuclide j ;
-Ak, j is the activity of each source k containing radionuclide j. Unless otherwise specified, the activity taken into account takes radioactive decay into account;
-Sj is the activity level defined in the second column of Table 2 of Annex 13-8 to Part I of this Code for radionuclide j.
A batch of radioactive sources is classified as category C if the batch contains no high activity sealed source contained in a mobile or portable device and if the ratio :
You can consult the full text with its images from the authenticated electronic Official Journal extract accessible at the following address https :// www. legifrance. gouv. fr/ jo _ pdf. do ? id = JORFTEXT000036984723
is greater than or equal to 1,
and if the ratio :
You can consult the full text with its images from the authenticated electronic Official Journal extract accessible at the following address https :// www. legifrance. gouv. fr/ jo _ pdf. do ? id = JORFTEXT000036984723
is less than 1,
where
-n is the number of different radionuclides contained in the sources in the batch ;
-i is the number of sources in the batch containing radionuclide j ;
-Ak, j is the activity of each source k containing radionuclide j. Unless otherwise specified, the activity taken into account takes radioactive decay into account;
-SCj is the activity level defined in the fifth column of Table 2 of Annex 13-8 to Part I of this Code for radionuclide j ;
-SBj is the activity level defined in the sixth column of Table 2 of Annex 13-8 to Part I of this Code for radionuclide j.
A batch of radioactive sources is classified in category B if the :
You can consult the full text with its images from the authenticated electronic Official Journal extract accessible at the following address https :// www. legifrance. gouv. fr/ jo _ pdf. do ? id = JORFTEXT000036984723
is greater than or equal to 1,
and if the ratio :
You can consult the full text with its images from the authenticated electronic Official Journal extract accessible at the following address https :// www. legifrance. gouv. fr/ jo _ pdf. do ? id = JORFTEXT000036984723
is less than 1,
where
-n is the number of different radionuclides contained in the sources in the batch ;
-i is the number of sources in the batch containing radionuclide j ;
-Ak, j is the activity of each source k containing radionuclide j. Unless otherwise specified, the activity taken into account takes radioactive decay into account;
-SBj is the activity level defined in the sixth column of Table 2 of Annex 13-8 to Part I of this Code for radionuclide j ;
-SAJ is the activity level defined in the seventh column of Table 2 of Annex 13-8 to Part I of this Code for radionuclide j.
A batch of radioactive sources is classified in category A if the :
You can consult the full text with its images from the authenticated electronic Official Journal extract accessible at the following address https :// www. legifrance. gouv. fr/ jo _ pdf. do ? id = JORFTEXT000036984723
is greater than or equal to 1,
where
-n is the number of different radionuclides contained in the sources in the batch ;
-i is the number of sources in the batch containing radionuclide j
-Ak, j is the activity of each source k containing radionuclide j. Unless otherwise specified, the activity taken into account takes radioactive decay into account.
-SAj is the activity level defined in the seventh column of Table 2 of Annex 13-8 to Part I of this Code for radionuclide j.
A batch of radioactive sources is classified in category D in all other cases.
Reference level: value used in the situations mentioned in Article L. 1333-3 to define the level of effective dose or equivalent dose or activity concentration above which it is deemed inappropriate to allow exposure to ionising radiation resulting from the said situation, even if it is not a limit that cannot be exceeded. Optimisation of protection focuses on exposures above the reference level and continues to be implemented below it to reduce exposures as low as reasonably achievable.
Diagnostic reference level: dose level for types of radiological procedures and radioguided interventional practices or, in the case of radiopharmaceuticals, activity levels, for typical groups of patients or typical phantoms, for categories of equipment.
Nucleide: atomic species defined by its mass number, atomic number and nuclear energy state.
Representative person: a person receiving a dose who is representative of the most exposed people in the population, excluding people with extreme or rare habits.
Radon potential: the radon potential of geological formations is determined by the uranium content of the underlying soil, which is the primary factor influencing the concentration levels measured in buildings. In a given geographical area, the higher the potential, the greater the likelihood of high levels of radon in buildings.
Radioguided interventional practices: all imaging techniques using ionising radiation to perform invasive medical or surgical procedures for diagnostic, preventive or therapeutic purposes, as well as surgical and medical procedures using ionising radiation for guidance or control purposes.
Radioactivity: phenomenon of spontaneous transformation of a nuclide with emission of ionising radiation.
Radionuclide: radioactive nuclide.
Ionising radiation: transport of energy in the form of particles or electromagnetic waves with a wavelength of 100 nanometres or less, or a frequency of 3 x 1015 hertz or more, which can produce ions directly or indirectly.
Sievert: the name of the unit of equivalent dose or effective dose (one sievert is equivalent to one joule per kilogram).
Site polluted by radioactive substances: site which, as a result of former deposits of radioactive substances or waste, use or infiltration of radioactive substances or radiological activation of materials, presents a radioactive pollution likely to cause a nuisance or a lasting risk for people or the environment.
Source of ionising radiation: entity likely to cause exposure, for example by emitting ionising radiation or releasing radioactive substances.
Natural source of ionising radiation: source of ionising radiation of natural terrestrial or cosmic origin.
Radioactive source: source of ionising radiation containing radioactive substances.
Orphan radioactive source: radioactive source that is not covered by an exemption and is not or has never been under regulatory control.
Sealed radioactive source: radioactive source in which the radioactive substances are permanently enclosed in a capsule or incorporated in solid form in order to prevent, under normal conditions of use, any dispersion of radioactive substances.
High activity sealed source: sealed radioactive source containing a radionuclide whose activity is equal to or greater than the activity level defined for this radionuclide in the fifth column of Table 2 of Annex 13-8 of Part I of this Code. Unless otherwise specified, the classification of a radioactive source as a high activity sealed source is established taking into account radioactive decay.
Naturally-occurring radioactive substance: any substance containing one or more naturally-occurring radionuclides not used for their radioactive, fissile or fertile properties, the mass activity concentration(s) of which exceed(s) one or more exemption limit values defined in Table 1 of Annex 13-8 to Part I of this Code.
Use: any treatment, handling or use of a source of ionising radiation or, more generally, any operation carried out on or with the aid of a source of ionising radiation, with the exception of its manufacture and the transport of radioactive substances.
