CHARACTERIZATION OF PLUTONIUM CONTAMINATION AT THE FORMER NUCLEAR-WEAPONS TESTING RANGE AT MARALINGA IN SOUTH-AUSTRALIA

Re-suspension studies on soils contaminated with plutonium during nucl ear weapons tests were performed by use of a mechanical dust-raising a pparatus. Airborne dust was analyzed in terms of mass and Am-241 activ ities for particle sizes less than 7 mum. The AMAD was determined as 4 .8 to 6 mum for re-suspended soil. Also, surface soil was characterize d in the laboratory by means of sieving and microparticle classificati on, yielding mass and Am-241 activity distributions with respect to si ze. Data indicate the granularity of plutonium contamination at both m ajor and minor trial sites. Depth profile analyses for undisturbed are as demonstrate that most (74% on average) of the americium and plutoni um activity is found in the top 10 mm of soil. Plutonium and americium activities were found to be enhanced in the inhalable fraction over t heir values in the total soil, arid the enhancement factors were simil ar in re-suspended dust and surface soil. Observed enhancement factors ranged from 3.7 to 32.5.