3. Framework for managing existing exposure situations
The framework for managing existing exposure situations is derived from the requirements of GSR Part 3 (IAEA 2014) and is based on the most recent Recommendations of the ICRP, as laid out in Publication 103 (ICRP 2007).
3.1 General guidance
|Responsibilities specific to existing exposure situations|
When an existing exposure situation is identified, responsibilities for protection and safety should be assigned and appropriate reference levels should be established (see Annex A).
The legal and regulatory framework for protection and safety should include provision for the management of existing exposure situations. The legal and regulatory framework, should as appropriate:
An established protection strategy for an existing exposure situation should ensure that it specifies
The implementation of the protection strategy should include:
3.2 Guidance for public exposure
The clauses in respect of public exposure in existing exposure situations (clauses 3.2.1-3.2.17) apply to any public exposure arising from the situations specified in Section 1.4.
|Justification for protective actions and optimisation of protection and safety|
A protection strategy for the management of existing exposure situations should be established in accordance with clauses 3.1.1 and 3.1.3, commensurate with the radiation risks associated with the existing exposure situation, and that remedial actions or protective actions are expected to yield sufficient benefits to outweigh the detriments associated with taking them, including detriments in the form of radiation risks.3
Remedial actions or protective actions should ensure that the form, scale and duration of such actions are optimised. While this optimisation process is intended to provide optimised protection for all individuals and non-human biota subjected to exposure, priority must be given to those groups for whom the dose exceeds the reference level. All reasonable steps should be taken to prevent doses from remaining above the reference levels. Reference levels should typically be expressed as an annual effective dose to the representative person in the range of 1-20 mSv or other corresponding quantity, the actual value depending on the feasibility of controlling the situation and on experience in managing similar situations in the past. For non-human biota, general guidance outlined in RPS G-1 (ARPANSA 2015) can be applied, as appropriate.
There should be a periodic review of reference levels to ensure that they remain appropriate in the light of the prevailing circumstances
|Responsibilities for remediation of areas with residual radioactive material|
For the remediation of areas with residual radioactive material deriving from past activities or from a nuclear or radiological emergency (Section 1.4(a)), provisions should be made in the framework for protection and safety for:
A strategy for radioactive waste management should be put in place to deal with any waste arising from the remedial actions, ensuring that provision for such a strategy is made in the framework for protection and safety.
The persons or organisations responsible for the planning, implementation and verification of remedial actions should, as appropriate, ensure that:
The relevant regulatory body should take responsibility for:
The person or organisation responsible for carrying out the remedial actions should:
After the remedial actions have been completed, the relevant regulatory body should:
The person or organisation responsible for post–remediation control measures should establish and maintain, for as long as required by the relevant regulatory body, an appropriate program, including any necessary provision for monitoring, to verify the long term effectiveness of the completed remedial actions for areas in which controls are required after remediation
For those areas with long lasting residual radioactive material, in which a decision has been made to allow habitation and the resumption of social and economic activities, the relevant regulatory body, in consultation with interested parties should ensure that arrangements that are in place, as necessary, for the continuing control of exposure with the aim of establishing conditions for sustainable living, including:
The conditions prevailing after the completion of remedial actions, if no restriction or controls have been imposed, should be considered to constitute the background radiation conditions for the purpose of assessing the radiological impact resulting from any future use of the site.
|Public exposure due to radon indoors|
As stated in clause 3.1.2, there should be assurance that:
Where activity concentrations of radon, that are of concern for public health and workers that are not considered occupationally exposed, are identified on the basis of the information gathered as required in clause 3.2.13 (a), an action plan should be established comprising coordinated actions to reduce activity concentrations of radon in existing buildings and in future buildings, which includes5
|3.2.15||An Responsibility should be assigned for:|
|Exposure due to radionuclides in commodities|
There should be established specific reference levels for exposure due to radionuclides in commodities such as construction materials, food, animal feed and drinking water, each of which should typically be expressed as, or be based on, an annual effective dose to the representative person that generally does not exceed a value of about 1 mSv (see Annex A).
Consideration should be given to the guideline levels for radionuclides in food traded internationally that could contain radioactive substances as a result of a nuclear or radiological emergency, which have been published by the Joint Food and Agriculture Organization of the United Nations, and the World Health Organization Codex Alimentarius Commission (FAO/WHO 2016). Consideration should be given to the guideline levels for radionuclides contained in drinking water that have been published by the World Health Organization (WHO 2011) (see Annex A).
3.3 Guidance for occupational exposure
The clauses in respect of occupational exposure in existing exposure situations (clauses 3.3.1-3.3.8) apply to any occupational exposure arising from the situations specified in Section 1.4.
|Exposure in occupationally exposed workplaces|
The clauses in respect of public exposure stated in clauses 3.2.1-3.2.3 should be applied to protection and safety for workers in existing exposure situations, other than in those specific situations identified in clauses 3.3.2-3.3.8.
|Remediation of areas with residual radioactive material|
Employers should ensure that the exposure of workers undertaking remedial actions is controlled in accordance with the relevant clauses on occupational exposure in planned exposure situations as established in Section 3 of the Code for Radiation Protection in Planned Exposure Situations, RPS C-1 (ARPANSA 2016).
|Exposure due to radon in workplaces|
A strategy for protection against exposure due to ²²²Rn in workplaces should be established, including the establishment of an appropriate reference level for ²²²Rn. The derived reference level for ²²²Rn should be set at a value which does not exceed an annual average activity concentration of ²²²Rn of 1000 Bq m-3, with account taken of the prevailing social and economic circumstances8 (see Annex A).
Employers should ensure that activity concentrations of ²²²Rn in workplaces are as low as reasonably achievable below the derived reference level established in accordance with clause 3.3.3, and should ensure that protection is optimised.
If, despite all reasonable efforts by the employer to reduce activity concentrations of radon, the activity concentration of ²²²Rn in workplaces remains above the derived reference level established in accordance with clause 3.3.3, the relevant clauses for occupational exposure in planned exposure situations as stated in Section 3 of the Code for Radiation Protection in Planned Exposure Situations, RPS C-1 (ARPANSA 2016) must apply.
|Exposure of aircrew due to cosmic radiation|
A determination should be made of whether an assessment of the exposure to aircrew due to cosmic radiation is warranted (see Section 4.3).
Where such assessment is deemed to be warranted, there should be an established framework which should include a reference level of dose and a methodology for the assessment and recording of doses received by aircrew from occupational exposure to cosmic radiation (see Annex A).
In accordance with clause 3.3.7:
- In the case of exposure due to radon, the types of situations that are included in the scope of existing exposure situations will include exposure in workplaces for which the exposure due to radon is not required by or directly related to the work and for which annual average activity concentrations due to 222Rn might be expected not to exceed the derived reference level established in accordance with clause 3.3.3.
- Such actions include remedial actions such as the removal or reduction of the source giving rise to the exposure, as well as other longer term protective actions such as restriction of the use of construction materials, restriction of the consumption of foodstuffs and restriction of land use or of access to land or buildings.
- The implementation of remedial actions (remediation) does not imply the elimination of all radioactivity or all traces of radioactive substances. The optimisation process may lead to extensive remediation but not necessarily to the restoration of previous conditions.
- Buildings with high occupancy factors for members of the public including kindergartens, schools and hospitals.
- Guidance on the preparation of an action plan for radon is provided by the World Health Organization (WHO 2009).
- On the assumption of an equilibrium factor for 222Rn of 0.4 and an annual occupancy of 7000 h, the value of activity concentration due to 222Rn of 200 Bq m-3 corresponds to an annual effective dose of 10 mSv.
- Examples of giving priority to reducing activity concentrations of 222Rn in those situations for which such action is likely to be most effective include (i) specifying the levels of activity concentrations of 222Rn in dwellings and other buildings with high occupancy factors at which protection can be considered optimised; (ii) identifying radon prone areas; (iii) identifying characteristics of buildings that are likely to give rise to elevated activity concentrations of 222Rn; and (iv) identifying and requiring preventative measures for radon in future buildings that can be introduced at relatively low cost.
- On the assumption of an equilibrium factor for 222Rn of 0.4 and an annual occupancy of 2000 h, the value of activity concentration due to 222Rn of 1000 Bq m-3 corresponds to an annual effective dose of 10 mSv.