1. Introduction

1.1 Citation

This publication may be cited as the Existing Exposure Guide (2017).

1.2 Background

The International Commission on Radiological Protection (ICRP) in its 2007 Recommendations of the International Commission on Radiological Protection, ICRP Publication 103 (ICRP 2007), takes a consistent approach for all types of radiation exposure situations, with the central consideration being the optimisation of radiation protection.

This Guide applies to existing exposure situations and aims to promote the implementation of the relevant requirements of the International Atomic Energy Agency (IAEA) General Safety Requirements Part 3, Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards (GSR Part 3) (IAEA 2014). Appendix 1 lists the guidance contained in this publication, cross–referenced to GSR Part 3. GSR Part 3 is published on the IAEA website.

1.3 Purpose

The purpose of this Guide is to provide guidance on protection of occupationally exposed persons, members of the public, and of the environment; from the harmful effects of ionising radiation in existing exposure situations.

1.4 Scope

This Guide applies to existing exposure situations, for the control of occupational exposure, public exposure and environmental exposure. Existing exposure situations are exposure situations that already exist when a decision on the need for control has to be taken, including prolonged exposure situations after emergencies. The Guide establishes a framework for existing exposure situations within Australia and is derived from recent ICRP and IAEA recommendations, in particular the requirements of GSR Part 3. These clauses in this Guide largely paraphrase GSR Part 3, to promote consistency with best practice for existing exposure situations.

Existing exposure situations in this Guide apply to exposure due to:

  1. contamination of areas by residual radioactive material deriving from:
    1. past activities that were never subject to regulatory control or that were subject to regulatory control but which resulted in situations that, if they were being controlled today, do not meet current radiation protection standards
    2. a nuclear or radiological emergency, after the response to the emergency has been declared to be ended
  2. commodities, including food, animal feed, drinking water and construction materials, that incorporate radionuclides deriving from, or contaminated by, material stated in (a) above or contaminated by radioactive material
  3. natural sources, including:
    1. radon and radon progeny in workplaces, other than those workplaces for which exposure due to other radionuclides in the uranium decay chain or the thorium decay chain is controlled as a planned exposure situation, in dwellings, and in other buildings with high occupancy factors for members of the public and workers who are not considered occupationally exposed
    2. radionuclides of natural origin, regardless of activity concentration, in commodities including food, animal feed, drinking water, agricultural fertiliser and soil amendments, construction materials, and residual radioactive material in the environment
    3. materials, other than those stated in (c)(ii) above, in which the activity concentration of no radionuclide in either the uranium decay chain or the thorium decay chain exceeds 1 Bq g-1 and the activity concentration of 40K exceeds 10 Bq g-1. When these conditions are exceeded in any practice, treatment as a planned exposure situation is required
    4. exposure of aircrew to cosmic radiation.

The application of this guidance is intended to ensure that suitable protective measures are taken to reduce any adverse health effects, by preventing tissue reactions (deterministic effects) and by reducing the risk of stochastic health effects to both members of the public and workers, in existing exposure situations. It therefore considers all hazard types in Australia regardless of potential consequences. This guide applies a risk based approach when considering justification and optimisation of strategies for managing existing exposure including remedial actions and protective actions.

Wildlife may require protection in order to maintain biological diversity, conservation of species, or the health and status of natural habitats, communities or ecosystems, or anything that may be otherwise required from a conservation point of view in accordance with relevant legislation.

1.5 Interpretation

This Guide is explanatory in nature and is not required to be complied with per se. Jurisdictions may, at their discretion, mandate clauses in Section 3 within their respective legal and regulatory framework. While clauses in the Code for Radiation Protection in Planned Exposure Situations (RPS C‑1) (ARPANSA 2016) do not apply directly to existing exposure situations, some remedial or protective actions may trigger relevant clauses in RPS C-1.

1.6 Structure

This Guide consists of four Sections, an Annex, two Appendices, a Glossary and References.

  • Section 1 describes the background, purpose and scope of the Guide.
  • Section 2 describes the radiation protection principles for existing exposure situations.
  • Section 3 describes the framework for managing existing exposure situations.
  • Section 4 describes considerations for radiation protection in existing exposure situations.
  • Annex A provides guidance on the implementation of reference levels in existing exposure situations in Australia.
  • Appendix 1 provides the existing exposure guide clauses from the GSR Part 3 Requirements.
  • Appendix 2 provides the ten principles of radiation risk management from the fundamentals for protection against ionising radiation (RPS F-1).

The meanings of technical terms used in this Guide are defined in the Glossary. Terms defined in the Glossary appear in bold type on first mention in the text. Publications underpinning this Guide are listed in the References section.

Additional guidance relating to specific scenarios can be found with electronic versions of this Guide on the ARPANSA website, www.arpansa.gov.au.

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