Ground truthing of an airborne gamma survey and assessment of the radiological conditions of the Sleisbeck mine area

Department of the Environment and Heritage, 2007

Internal Report 526
A Bollhöfer, K Pfitzner, B Ryan & M Fawcett
Supervising Scientist Division

About the report

This report describes the results of the radiological characterisation of the Sleisbeck mine, one of the many small abandoned uranium mine sites located in and around the South Alligator River Valley in the remote Northern Territory of Australia. The mine site is situated in the Katherine River catchment, ~30 km south east of Coronation Hill. This report is part of a larger study aimed at characterising the extent and intensity of radiological contamination in the area as a result of mining in the 1950s and 60s, and to assist in determining rehabilitation requirements. Although there is no reason for intervention on radiological grounds as annual radiation doses are low, the area is sparsely populated and access to many of the sites, including Sleisbeck, is restricted on cultural grounds, rehabilitation works have begun at the request of the Traditional Owners of the area.

A high resolution airborne gamma survey (AGS) of the Sleisbeck site was commissioned in 2002 to provide information about the extent of residual radiological contamination. The survey resulted in the collection of airborne radiometric data (eU, eTh, K and total count rates), magnetic, and digital elevation data. A NaI(Tl) detector with a 48 litre detector volume was used, with sampling occurring every 1 second. A flight line spacing of 25 m, with 250 m tie line spacing, and an aircraft height of 40 m were chosen for the survey, providing unusually high spatial resolution of the images.