Mapping Nuclear Fallout Patterns over Maralinga, South Australia, more than Sixty Years after Atomic Bomb Testing

Nuclear bombs were detonated in trial conducted at Maralinga, Soth Australia in the 1950s and 60s. The radioactive fallout from the atomic bomb sites has not been adequately surveyed. In this study, we use airborne gamma ray spectrometry data, collected in surveys conducted between 1993 and 2018. The distribution of 137Cs following the seven nuclear test blasts at Maralinga can be mapped after 60 years and several NE to E-trending plumes of 137Cs contamination are visible for at least 70 km. A clear signature for 241Am, a daughter product of the plutonium dispersed by so-called “minor” trials was also extracted. Our results show that, despite several official attempts at remediation of contaminated ground at Maralinga, radioactive material remains over an area of approximately 3000 km2. We suggest that a properly calibrated, high resolution airborne gamma ray spectrometry survey over Maralinga is necessary to map the full extent of radioactive fallout, and to provide guidance regarding safe access for the traditional owners.