b'FeatureAirborne radiometrics over Maralinga - call for a new survey In a report published in 2021, a Monash University team led by Megan Cook concluded that plutonium rich nano particles are quite likely to become available to humans at Maralinga, not only by inhalation in windy, dusty conditions but also through ingestion if plants and animal from the area are eaten. They also concluded that the smaller the particles the greater the toxicity (Cook et al. 2021).In 1987 The Australian Radiation Laboratories conducted ground-based surveys along the Oak Valley Road and Western Avenue using a high purity germanium detector to ascertain, among other things, the level of plutonium likely to a\x1fect Aboriginal township of Oak Valley. Measurements were con\x1ened mostly to roads and tracks and no grid pattern was attempted. They reported that these traverses were di\x1bcult to establish, and positions estimated along them must be considered approximate with a likely accuracy of plus or minus 500 m, see Figure 17 (Johnson et al. 1989).Johnson at al.s 1989 map guides the monitoring of the site today. The ten observation points are visited annually, and americium levels are obtained (Long and Green 2012):Of the \x1eve surveys reviewed over Maralinga, none wereFigure 17. Map of the Americium plumes used for rehabilitation and testing showing ten sampling points and plume contours compiled by Johnson et al completely \x1et for the purpose. The EG&G survey su\x1fered fromin1989.antiquated equipment and primitive processing techniques. The World Geoscience survey su\x1fered from ignorance of tracking anthropogenic radioisotopes. The other (government) surveys were designed for acquisition of regional data for geological mapping. The remarkable results from the Thomson Aviation survey point to what could be possible if a modern survey was \x1cown with speci\x1ecations designed to detect man-made isotopes. Now is the optimum time for such a survey, as the plutonium marker isotope Am 241 has been increasing for about 70 years and is at or near its maximum (Table 3).Unfortunately, the recommendations of the Australian Governments Technical Advisory Group report were onlyFigure 18. Cessna 206 engaged in Airborne Radiometric/Magnetic survey partially followed through. No airborne magnetometer surveyCoober Pedy South Australia (Source SADME).was conducted. No systematic ground geophysical surveys wereconducted.Todays GPS based positioning would provide, via these new surveys, an accurate set of maps suitable for soil geochemistry Conclusion sampling and analysis and other studies. The present system of relating samples to roads and tracks is just too antiquated. The regional information that the authorities responsible forThe readings may be accurate, but they are only as good as Maralinga are forced to use is seriously de\x1ecient. Toxic plutoniumtheirpositioning.239 is e\x1fectively with us forever. An airborne magnetic/ radiometric survey should be \x1cown to Geoscience Australia standards at a \x1cying height of 40 m and a line spacing of 40 m.AcknowledgementsThis could be economically performed by a light aircraft such as a Cessna 206 (Figure 18) with an across-ground speed of60 m/s. Bob Pavlik, Joe Kita, Pavel Jurza, Jane Cunneen, Bob Timmins and Greg Street gave generously of their time and expertise, Selective helicopter surveys over major contamination shouldbutI thank them mostly for their patience, which, Im afraid, follow. The position and activity concentration of the plumesIsorely tested.would be known for the \x1erst time as would the e\x1fectiveness of the various clean-up e\x1forts. The value of Maralinga as an historical area in a stable pristine environment for the study ofReferencesanthropogenic radioisotopes is rarely appreciated. It should be regarded as a place for the study of radioisotopes. Australian Atomic Energy Commission (AAEC). 1985. Options for clean-up of the Maralinga test site. AAEC/DR20.A helicopter electromagnetic survey should also be \x1cown overAustralian Ionising Radiation Advisory Council (AIRAC). 1979. Radiological the area of the pits, containing as they do many hundredssafety and future land use at the Maralinga atomic weapons test range. Report of tonnes of steel. In addition, a ground based, fully griddedNo. 4, AGPS, Canberra.electromagnetic, magnetic and radiometric survey over selectedBurns, P.A., M.B. Cooper and K.H. Lok. 1995.Characteristics of plutonium pits and plumes should be conducted to give custodians of theand americium contamination at the former U.K. atomic weapons ranges at range, now and in the future, the management tools they need. Maralinga and Emu. Applied Radiation. 46 (11): 1099APRIL 2024PREVIEW 55'