Case Studies in Existing Exposure Situations ARPS Conference, Adelaide, September 2016 Fiona Charalambous, Geoff Williams, Rick Tinker and Stephen Solomon
Purpose To discuss and examine the different types of existing exposure situations according to the IAEA Basic Safety Standards (GSR Part 3) To update the public and stakeholders on ARPANSA s progress towards the development of the Code for Radiation Protection in Existing Exposure Situations
Exposure Situations Existing Planned Emergency Already there when a decision on control needs to be made Deliberately introduced and fully under control Loss of control or unexpectedly introduced
Types of Existing Exposure Situations Radon in homes and workplaces Legacy sites Commodities Aircrew and Space crew Existing Exposure A situation that already exists when a decision on the need for control needs to be taken Bulk material from natural sources
Reference Levels Reference levels, in existing exposure situations are defined as the level of individual dose above which it is judged to be inappropriate to allow exposures to occur, and below which the goal is to reduce all doses ALARA
Key factors informing the selection of the reference level Remediation is almost always justified 20 msv/y Factors tending to increase the reference level: Benefits to individuals arising from more limited remediation such as quicker return to normal living Practicability / Availability of resources Higher uncertainty Preservation and use of environmental, social and cultural resources Large quantities of residual material or waste anticipated Remediation is almost always justified Factors tending to decrease the reference level: Detriment to health caused by radiation Difficulty of implementing self-help measures Public perception / fear of radiation Remediation measures that are easily achieved / low cost Lower uncertainty Remediation is unlikely to be justified 20 msv/y Reference Level 1 msv/y Remediation is unlikely to be justified 1 msv/y 6
Aircrew and Cosmic Radiation Pilots and aircrew are exposed to elevated levels of cosmic radiation while flying at high altitude Monitoring records show that exposures are up to a third the occupational dose limit of 20 msv per year that applies to planned exposure situations These doses are similar to those experienced by aircrew in other countries The airline industry mitigates the risk of exposure by restricting staff flying hours Cosmic radiation exposure to aircrew is currently selfregulated by the airline industry by using reference levels according to international best practice The reference level for aircrew is 6 msv y -1
Exposure to Radon in Homes Radon is a naturally occurring radioactive gas and is present outdoors and indoors The result of a nationwide survey of radon in Australian homes, indicated the average concentration of radon in Australian homes was low, approximately one quarter the worldwide average The current Australian action level for radon in homes is 200 Bq m -3 A small number of homes have been identified with radon levels above the reference level, but to date no remediation to reduce radon levels has been undertaken in Australia
Exposure to Radon in Workplaces The current Australian action level for radon in workplaces is 1000 Bq m -3 There are workplace environments where radon levels can be very high Levels of exposure to radon in an cave can be mitigated by reducing staff time underground
Past Practices / Legacy Sites Some past activities, practices and or accidents have resulted in contamination of the environment with radioactive material For current work practices, a post operations plan is required in order to obtain a licence from the regulators within Australia A remediation process will include the establishment of a reference level in the range 1 to 20 msv y -1
Maralinga A legacy site requiring major remediation is the former nuclear weapons testing site at Maralinga A monument of the Taranaki nuclear test site Between 1955 and 1963, the United Kingdom conducted a program of nuclear weapons testing in Australia at Maralinga and Emu Field in the remote outback of South Australia and the Western Australian Montebello Islands One Tree (12.9 kt) The testing led to widespread dispersal of radioactive contamination to the local environment Friable Uranium
Maralinga Legacy Site Following a detailed analysis, a reference level of 5 msv y -1 was set For the remediation strategy, a variety of stakeholders were consulted Once remediation was completed verification monitoring was performed A post - remediation dose assessment was completed Remediation of the Maralinga site was completed in 2000 The remediated site has been returned to the traditional owners The remediation of Maralinga is seen internationally as best practice
Update on the Existing Exposure Code A Preliminary Assessment was to submit to the Office of Best Practice Regulation Regulatory Impact Statement is not required for the Existing Exposure Code A draft document has been circulated to the Radiation Health Committee for comment
Questions? Email: fiona.charalambous@arpansa.gov.au Website: www.arpansa.gov.au Telephone: +61 3 9433 2404 (direct) General Fax: +61 3 9432 1835