Working with radiation
ANSTO has strong systems in place to ensure operations are safe for employees and the community, and in line with international best practice. International standards for the safety of workers and members of the public are set by bodies such as the International Commission on Radiological Protection and the International Atomic Energy Agency.
The recommendations of both the ICRP and IAEA form the basis of Australian legislation on the use of radiation and radioactivity (see Regulations governing ANSTO).
The key principles for radiation protection by ICRP are:
- Justification: All activities involving exposure to radiation, or radioactive materials, must be justified as producing a positive net benefit. That is, the benefits from an activity must always outweigh the risks to those carrying out the activity.
- Optimisation: All exposures to radiation or radioactive material must be minimised. ANSTO applies the principle that all radiation exposures shall be maintained As Low As Reasonably Achievable. In line with ANSTO's commitment to continuous improvement, this means that, as new technologies become available, the organisation will seek to continuously reduce radiation exposures associated with its activities.
- Limitation: All exposures must be kept below the statutory dose limits specified in the ARPANS Act.
Current mandated annual limits for occupational exposures are 20 millisieverts (mSv) for workers. ANSTO self-imposes a stricter annual dose constraint of 15 mSv for workers, and, on average our employees classified as "radiation workers" receive less than five per cent of this.
ANSTO has a target that the annual dose to the most potentially exposed member of the public from all routine discharges shall be less than 0.02 mSv (1/50th of the annual statutory dose limit), and recent estimates consider that the doses are around 1/5th of this target value.
In controlling the risks associated with radiation and radioactive material, ANSTO applies the general safety management principles described in How ANSTO manages safety. In particular, quantities of radioactive material are strictly controlled and exposures limited by engineered means.
Specific means of controlling the radiation hazard include the use of shielding materials such as lead, concrete or, in the case of OPAL, water to reduce the radiation field in working areas to acceptably low levels.
Shielding requirements are defined at the planning stages of new facilities and shielding is integrated into the design. Radiopharmaceutical production takes place in shielded hot cells, where operators utilise remote handling techniques to avoid direct exposure to radioactive material.
Active ventilation systems ensure that radioactive material is contained within defined enclosures and that any discharges to the environment are passed through high efficiency filter media, aimed at removing 99.99 per cent of respirable airborne particulate.
The engineering controls are supported by robust administrative controls which include the restriction of work with radiation, or radioactive material, to authorised areas and prior approval for all such activities.
All radiation workers undergo prior training and all occupational exposures and environmental discharges are monitored and reported both internally and to the relevant regulatory bodies.
The effectiveness of controls is kept under regular review to ensure that the level of radiological risks to staff and members of the public remains low.