Rehabilitation of the former Maralinga and Emu nuclear test sites
The following points provide information regarding rehabilitation of the Maralinga and Emu nuclear test sites, prior to its return in 2009 to the traditional owners, the Maralinga Tjarutja Aborigines.
About the Maralinga Rehabilitation Project
The Maralinga Rehabilitation Project successfully remediated the former British atomic test sites at Maralinga and Emu in South Australia.
A preferred rehabilitation option from a range of options developed by the Technical Assessment Group was agreed to in 1991 by the Australian and South Australian governments and the traditional owners.
Work commenced on the Project in 1996 and was completed in 2000.
The project was conducted in accordance with International Atomic Energy Agency and International Commission on Radiological Protection guidelines on rehabilitation of contaminated sites, and relevant Australian codes of practice. The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) monitored the project, and issued clearance certificates for the remediated areas.
The project was successful, and surpassed the clean-up standards set at its commencement. Most of the former Maralinga test site (approximately 3200 square kilometres) is now safe for unrestricted access. As a precautionary measure, approximately 120 square kilometres, enclosed within an area of 412 square kilometres delineated by marker posts, is considered safe for access but not for permanent occupancy.
In November 2009 the Australian and South Australian Governments and Maralinga Tjarutja signed the Maralinga Nuclear Test Site Handback Deed, which gave effect to the return of the test site to traditional owners. The handback was celebrated at a ceremony at Maralinga Village on 18 December 2009.
Why was rehabilitation of the Maralinga test sites necessary?
Between 1953 and 1957, the British Government conducted nine nuclear weapon tests in the north of South Australia with the support of the Australian Government. Following two tests at Emu, Maralinga was developed as a permanent nuclear test site and was the site of the Operation Buffalo (1956) and Operation Antler (1957) nuclear weapons tests.
Two nuclear devices were detonated at Emu and seven at Maralinga. Most of the nuclear devices at Maralinga were detonated on 30-metre towers, with some others detonated at higher altitude (from balloons) and at ground level. These nuclear explosions were not the major cause of contamination at Maralinga, as the heat and energy of the fission explosions drew much of the contamination up into the atmosphere.
The major cause of contamination at Maralinga was the minor trials. The minor trials did not involve nuclear explosions. They were weapons development trials to investigate the performance of various components of a nuclear device. Almost all involved use of radioactive materials in conjunction with conventional high explosives. The British Government conducted about two hundred minor trials between 1953 and 1963. Many of the minor trials involved short-lived radionuclides, but the trials at three sites Taranaki, TM100/101 (TMs), and Wewak dispersed long-lived plutonium over the surrounding land which presented a significant health hazard to any future occupants.
Maralinga was officially closed following a British clean-up operation (Operation Brumby) in 1967.
Types of contamination at the sites
Plutonium was the major radiological contaminant at Maralinga. It was dispersed into the surrounding area by the minor trials and detonation of nuclear devices.
Plutonium is a hazard to humans if inhaled, ingested, or absorbed through breaks in the skin. External exposure to plutonium does not pose a health risk, as the element emits alpha particles which do not pass through unbroken skin.
There were small quantities of other radiological contaminants and uranium fragments. Uranium is not a radiological hazard, but can be toxic to humans if ingested in large enough quantities.
The decision to undertake a rehabilitation plan
In 1985, the Royal Commission into British Nuclear Tests in Australia recommended that the test sites at Maralinga and Emu be remediated to be fit for unrestricted habitation by the traditional owners.
To read the Royal Commission into British Nuclear Test in Australia, see Related documents.
The Technical Assessment Group (TAG) was established in 1986 to advise the Australian Government on rehabilitation options and their costs.
TAG was comprised of Australian, British and American scientists with expertise in radiological protection, nuclear engineering and radiological decontamination. An extensive program of scientific and engineering studies was conducted, which showed that residual plutonium contamination of soil from the minor trials and the consequent risk of inhalation of contaminated dust was the predominant contributor to potential radiation dose at Maralinga. TAG assessed the level at which the risks became unacceptable for Aborigines living a semi-traditional lifestyle.
The 1990 TAG Report presented the Australian Government with a range of costed options for rehabilitating the Maralinga lands. In 1991, the Australian Government, the South Australian Government, and the traditional owners, Maralinga Tjarutja, reached agreement on a preferred option, which permitted unrestricted access to all but an approximately 120 square kilometre area of test site land. To make the whole of the site available for unrestricted access would have required removal of a large area of surface soil. This option was rejected by Maralinga Tjarutja because of the potential environmental damage that it would have caused.
Maralinga Tjarutja was paid $13.5 million by the Australian Government in settlement of its claims concerning contamination and denial of access to test site land. As part of this settlement the Government agreed to provide training and employment opportunities to Maralinga Tjarutja during the Maralinga Rehabilitation Project.
What rehabilitation work was conducted at Maralinga?
Rehabilitation at Maralinga consisted of two parts.
The first part was removal of surface soil from the more contaminated areas. Over 350 000 cubic metres of contaminated soil and debris was removed from the surface of just over two square kilometres of land. This contaminated soil was then buried in trenches 10–15 metres deep, under a capping of at least five metres of clean soil.
The second part was treatment of contaminated debris pits, left over from the 1967 British clean-up. Eleven pits were treated by in situ vitrification, a process that involved passing an electric current through electrodes in the ground to melt soil and debris and incorporate contaminants in a vitrified monolith (a glass/ceramic block), thereby immobilising the radiological contaminants. This process ended following an explosion of unknown cause during melting operations in 1999. Debris from the remaining pits was excavated and buried in trenches.
Marker plinths and signs were erected to mark the location of each burial trench. A revegetation program was conducted in areas where major earthworks were carried out. Boundary markers discouraging permanent habitation were erected where necessary.
What rehabilitation work was conducted at Emu?
Two atomic explosions and some minor trials were undertaken at Emu in the 1950s, 190 kilometres north-east of Maralinga. The main contaminant was plutonium incorporated in fused soil close to the detonation sites.
Because of the low level of radiological hazard presented by contamination at Emu, no major remedial work was undertaken at the site. Access tracks were removed and a revegetation program was conducted. Boundary markers discouraging permanent habitation were erected approximately 1 km from the detonation sites.
British responsibility for the contamination
The British Government conducted a series of clean-up operations at Maralinga and Emu between 1963 and 1967.
These clean-up operations were based on inaccurate measurements and a series of assumptions now recognised to be flawed. They did not rehabilitate the site to the standard now accepted as necessary for adequate protection of people and the environment. After the final clean-up operation, which was accepted by the Australian Government of the time, the British Government was largely released from any future liability.
In 1985, the Royal Commission into British Nuclear Tests in Australia recommended that the British Government should bear all costs for a future rehabilitation of Maralinga. In 1993, representations from the Australian Government and the traditional owners of the Maralinga lands resulted in the British Government making an ex-gratia payment of £20 million to the Australian Government. This amount was accepted as a significant contribution to the cost of the planned rehabilitation project.
To read the Royal Commission into British Nuclear Test in Australia, see Related documents.
Safety of the project
The project maintained an excellent safety record. Strict procedures consistent with best international practice were followed throughout the project to ensure that all works were undertaken safely and that workers were protected from radiological and other hazards.
No worker received a measurable uptake of plutonium during the project.
The involvement of Maralinga Tjarutja workers in the rehabilitation project
Maralinga Tjarutja workers were employed on the project—erecting boundary marker signs around restricted access areas, collecting native seeds for revegetation, and non-radiological hazard reduction works.
Indigenous workers were also employed by some subcontractors on the project to assist with earthworks, camp management and health physics.
Cost of the Maralinga rehabilitation project
The project was completed on time and within budget, for a little under $108 million in 1999 dollars.
The Royal Commission is published as three documents:
For more information about Maralinga, see Maralinga and British nuclear testing in Australia.