7.6.1 System for radiation protection

The system for managing risks from radiation (ARPANSA 2014) aims to assess, manage and control exposure to radiation so that radiation risks, including risks of health effects and risks to the environment, are reduced to the extent reasonably achievable.

The system for radiation protection and safety considers the following principles: justification, optimisation and dose limitation. In existing exposure situations, the principle of justification is applied in making the decision as to whether to take action to reduce the exposure. Once the decision to reduce the exposure has been made, optimisation of doses to the exposed group is carried out taking into consideration any economic and societal factors.

Australia implements a system of radiation protection in line with the International Atomic Energy Agency (IAEA) requirements. These are reflected in Radiation Protection Series (RPS) documents published by ARPANSA and developed jointly with states and territories. Exposure to radiation from drinking water meets the requirements of being an ‘existing exposure’ and is dealt with according to RPS G-2 Guide for Radiation Protection in Existing Exposure Situations.

Naturally occurring radionuclides and human-made radionuclides present in drinking water should not be managed differently. Radiation dose associated with the intake of a radionuclide into the body from drinking water does not depend on its source. Accordingly, the World Health Organization (WHO 2017) do not differentiate between radionuclides that occur naturally and those that arise from human activities in terms of the criteria included to assess health risks.

However, in terms of risk management, there is a difference because human-made (i.e. anthropogenic) radionuclides are often controllable through regulation before the point at which they may enter the water supply. Similarly, decisions to select between available water source options, such as which aquifers to draw from, are human-made and are often controllable through preventive risk management, keeping in mind the need to reduce health risks to the extent reasonably achievable. In contrast, naturally occurring radionuclides usually enter the water supply from the surrounding rocks and soil and are therefore often less amenable to control. This may influence the actions that are taken in the event that the criteria in the Guidelines are exceeded (more information can be found in Information Sheet 2.2).

For emergency exposure situations, the international guidance in the IAEA Safety Standards Series on preparedness and response for a nuclear or radiological emergency is used (IAEA 2015, IAEA 2011). In Australia, management of drinking water in emergency exposure situations is conducted in accordance with ARPANSA publication RPS G-3 Guide for Radiation Protection in Emergency Exposure Situations (ARPANSA 2019).