RPS G-2 - Framework for managing existing exposure situations

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

3.1.1

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).

3.1.2

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:

  1. specify the types of exposure situations that are included in the scope of existing exposure situations1
  2. specify the general principles underlying the protection strategies developed to reduce exposure when remedial actions and protective actions have been determined to be justified2
  3. assign responsibilities for the establishment and implementation of protection strategies to the relevant authorities and, as appropriate, to registrants, licensees and other parties involved in the implementation of remedial actions and protective actions
  4. provide for the involvement of interested parties in decisions regarding the development and implementation of protection strategies

3.1.3

An established protection strategy for an existing exposure situation should ensure that it specifies

  1. the objectives to be achieved by means of the protection strategy
  2. appropriate reference levels (see Annex A)

3.1.4

The implementation of the protection strategy should include:

  1. arrangements for evaluation of the available remedial actions and protective actions for achieving the objectives, and for evaluation of the efficacy of the actions planned and implemented
  2. ensuring that information is available, to individuals subject to exposure, on potential health risks and on the means available for reducing their exposures and the associated risks.
  3. consideration of environmental exposures and risks to non-human biota.

 

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

3.2.1

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

3.2.2

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.

3.2.3

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
3.2.4

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:

  1. the identification of those persons or organisations responsible for the contamination of areas and those responsible for financing the remediation program, and the determination of appropriate arrangements for alternative sources of funding if such persons or organisations are no longer present or are unable to meet their liabilities
  2. the designation of persons or organisations responsible for planning, implementing and verifying the results of remedial actions
  3. the establishment and ongoing review of any restrictions on the use of or access to the areas concerned before, during and, if necessary, after remediation
  4. an appropriate system for maintaining, retrieval and amendment of records which cover: the nature and the extent of contamination; the decisions made before, during and after remediation; and information on verification of the results of remedial actions, including the results of all monitoring programs after completion of the remedial actions
3.2.5

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.

3.2.6

The persons or organisations responsible for the planning, implementation and verification of remedial actions should, as appropriate, ensure that:

  1. a remedial action plan, supported by a safety assessment, is prepared and is submitted to the regulatory body for approval
  2. the remedial action plan is aimed at the timely and progressive reduction of the radiation risks and eventually, if possible, the removal of restrictions on the use of or access to the area
  3. any additional doses received by members of the public as a result of the remedial actions are justified on the basis of the resulting net benefit, including consideration of the consequent reduction of the annual dose
  4. in the choice of the optimised remediation option:
    1. radiological impacts on people and the environment are considered together with non–radiological impacts on people and the environment, including technical, societal and economic factors
    2. the costs of the transport and management of radioactive waste, the radiation exposure of and health risks to the workers managing the radioactive waste, and any subsequent public or environmental exposure associated with its disposal are all taken into account.
  5. a mechanism for public information is in place and interested parties are involved in the planning, implementation and verification of the remedial actions, including any monitoring following remediation
  6. a monitoring program is established and implemented
  7. a system is in place for maintaining adequate records relating to the existing exposure situation and for actions taken for protection and safety is in place
  8. procedures are in place for reporting to the relevant regulatory body on any abnormal conditions relevant to protection and safety.
3.2.7

The relevant regulatory body should take responsibility for:

  1. review of the safety assessment submitted by the responsible person or organisation, approval of the remedial action plan and of any subsequent changes to the remedial action plan, and granting of any necessary authorisation
  2. establishment of criteria and methods for assessing safety
  3. review of work procedures, monitoring programs and records
  4. review and approval of significant changes to procedures or equipment that may have radiological environmental impacts or that may alter the exposure conditions for workers taking remedial actions or for members of the public
  5. where necessary, establishment of regulatory requirements for control measures following remediation.
3.2.8

The person or organisation responsible for carrying out the remedial actions should:

  1. ensure that the work, including management of the radioactive waste arising from that work, is conducted in accordance with the remedial action plan
  2. take responsibility for all aspects of protection and safety, including undertaking a safety assessment
  3. monitor the area regularly during remediation so as to verify levels of contamination, to verify compliance with the requirements for radioactive waste management, and to enable any unexpected levels of radiation to be detected and the remedial action plan to be modified accordingly, subject to the approval of the relevant regulatory body
  4. perform a radiological survey after completion of remedial actions to demonstrate that the end point conditions, as established in the remedial action plan, have been met
  5. prepare and retain a final remediation report and should submit a copy to the relevant regulatory body.
3.2.9

After the remedial actions have been completed, the relevant regulatory body should:

  1. review, amend as necessary, and formalise the type, extent and duration of any post–remediation control measures already identified in the remedial action plan, with due consideration of the residual radiation risks
  2. identify the person or organisation responsible for any post–remediation control measures
  3. where necessary, impose specific restrictions for the remediated area to control:
    1. access by unauthorised persons or for unauthorised activities
    2. removal of radioactive material or use of such material, including its use in commodities
    3. future use of the area, including the use of water resources and its use for the production of food or animal feed, and the consumption of food from the area
  4. periodically review conditions in the remediated area and, if appropriate, should amend or remove any restrictions.
3.2.10

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

3.2.11

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:

  1. establishment of reference levels for protection and safety that are consistent with day-to-day life
  2. establishment of an infrastructure to support continuing ‘self-help protective actions’ in the affected areas, such as by the provision of information and advice, and by monitoring.
3.2.12

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
3.2.13

As stated in clause 3.1.2, there should be assurance that:

  1. information is gathered on activity concentrations of radon in dwellings and other buildings with high occupancy factors for members of the public4, through appropriate means, such as representative radon surveys (see Section 4.2)
  2. relevant information on exposure due to radon and the associated health risks, including the increased risks related to smoking, is provided to the public and other interested parties.
3.2.14

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

  1. establishing an appropriate derived reference level for ²²²Rn for dwellings and other buildings with high occupancy factors for members of the public, with account taken of the prevailing social and economic circumstances that in general will not exceed an annual average activity concentration due to ²²²Rn of 200 Bq m-36 (see Annex A)
  2. reducing activity concentrations of ²²²Rn and consequent exposures to levels at which protection is optimised
  3. giving priority to actions to reduce activity concentrations of ²²²Rn in those situations for which such action is likely to be most effective7
  4. amending building codes to include appropriate preventive measures and corrective actions to prevent the ingress of ²²²Rn and to facilitate further actions wherever necessary.
3.2.15 An Responsibility should be assigned for:
  1. establishing and implementing the action plan for controlling public exposure due to ²²²Rn indoors
  2. determining the circumstances under which actions are to be mandatory or are to be voluntary, with account taken of legal requirements and of the prevailing societal and economic circumstances.

 

Exposure due to radionuclides in commodities
3.2.16

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).

3.2.17

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
3.3.1

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
3.3.2

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
3.3.3

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).

3.3.4

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.

3.3.5

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
3.3.6

A determination should be made of whether an assessment of the exposure to aircrew due to cosmic radiation is warranted (see Section 4.3).

3.3.7

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).

3.3.8

In accordance with clause 3.3.7:

  1. where the doses of aircrew are likely to exceed the reference level, employers of aircrew should:
    1. assess and keep records of doses
    2. make records of doses available to aircrew
    3. apply 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).
  2. employers should:
    1. inform female aircrew of the risk to the embryo or foetus due to exposure to cosmic radiation and of the need for early notification of pregnancy
    2. apply clause 3.2.12 in the Code for Radiation Protection in Planned Exposure Situations, RPS C-1 (ARPANSA 2016) in respect of notification of pregnancy

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Footnotes:

  1. 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.
  2. 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.
  3. 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.
  4. Buildings with high occupancy factors for members of the public including kindergartens, schools and hospitals.
  5. Guidance on the preparation of an action plan for radon is provided by the World Health Organization (WHO 2009).
  6. 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.
  7. 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.
  8. 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.