Aboriginal children would receive doses of radiation more than 300 times the accepted limit if they were to live in the most highly contaminated regions of the former British nuclear test site at Maralinga in South Australia. This is revealed in a series of reports released in Canberra this week after a three-year study into levels of contamination at Maralinga and the costs of cleanup.
The cost of cleaning up could be as much as A $700 million (280 million Pounds), if the top-soil were removed. A much cheaper option, costing about A $13 million (5 million Pounds), would be simply to fence off the worst contaminated areas and keep people out.
The reports, which were presented to the Australian parliament on Wednesday, are likely to lead to a heated debate between the two national governments and the South Australian state government over which option to adopt and who should pay. Aboriginal groups will also demand compensation for land now denied them.
In 1985, a Royal Commission in Australia said that the contaminated lands should be made habitable again and that Britain should pay for the cleanup, but Britain rejected the finding. Britain may try to dodge responsibility again by claiming that it cleaned up when the forces left the area in 1967. However, the latest studies reveal that the cleanup, called Operation Brumby, was not as effective as claimed at the time by Noah Pearce, from the Atomic Weapons Research Establishment at Aldermaston, who investigated the operation for the British government.
‘Pearce reported that a person could spend 900 hours in the most contaminated areas before reaching the maximum concentration of plutonium,’ said Keith Lokan, director of the Australian Radiation Laboratory (ARL). ‘His report suggested that it was perfectly safe for the casual visitor. We wouldn’t agree with that now. The figure is more like nine hours.’ A report from the ARL says that only ‘intermittent forays’ should be allowed into the worst contaminated areas.
Australian scientists believe that ploughing or turning over the soil was not effective because contaminated fragments of material glazed by the intense heat were not removed first. The soil was not uniformly mixed, and instead has areas of high concentration of plutonium. The soils near Taranaki, the worst affected area, contain an estimated 3.3 terabecquerels (1012) of plutonium-239. Between 85 and 99 per cent of the radioactivity is in the top 20 millimetres of soil.
The main report was written by five radiation specialists from Britain, Australia and the US, who formed the Technical Assessment Group (TAG). Their estimates of the costs of cleaning up are based on reports from six other groups. These groups looked at the ways people could be exposed to the radiation, including ingestion of food and inhalation, the extent of contamination, and the lifestyle of the people most likely to use the area – the Maralinga Tjarutja aborigines.
Experiments done as part of the TAG study show that the worst exposure comes from breathing in dust. Aboriginal children are exposed to about 20 times as much airborne dust as city children.
The aborigines regularly travel between Oak Valley, Emu and Yallata. These settlements are well away from the worst contamination at Taranaki, but, on occasions, they travel across areas where plumes of plutonium settled. Scientists from the ARL say that these areas are not dangerous unless the aborigines stay for long periods.
Doses would be much higher near Taranaki, however. The ARL estimates that a child at Taranaki would be exposed to 306 millisieverts over a period of a year – 306 times the generally accepted limit. For an adult aborigine the dose would be 273 mSv per year.
To block off the most hazardous area of Taranaki would require a fence of about 25 kilometres by 15 kilometres. A few smaller pockets would also have to be fenced.