Evaluation of two procedures for assaying Uranium in soil

This research project evaluated two procedures for preparing soil samples for alpha counting. The first procedure is the Environmental Protection Agency's (EPA) procedure which is an adsorption precipitation method. The soil is digested with acid and the uranium is coprecipitated with a lanthanum fluoride precipitation. The lanthanum fluoride precipitation is filtered out of solution and counted. The second is a potassium fluoride (KF) fusion procedure which was developed from papers written by Drs. Claude and David Sill. The soil is fused into a pyrosulfate cake which is subsequently dissolved in 2M hydrochloric acid. The uranium is coprecipitated out of solution with barium sulfate and redissolved into solution. Then it is precipitated out of solution in a lanthanum fluoride coprecipitation. The precipitant is filtered and counted. A byproduct of this research was the setting up of a alpha counting laboratory and a chemistry laboratory.

Three different soil samples were analyzed with both the EPA and the potassium fluoride fusion procedures. The soil samples are from Fernald and were part of a blind test of laboratories in the United States. Both the EPA and the potassium fluoride fusion procedures yielded results which were statistically equivalent to the results obtained from the laboratories in the blind test.

Both procedures yielded results which were statistically equivalent for these soil samples. The EPA procedure takes approximately three days to prepare a sample for alpha counting. The potassium fluoride fusion procedure can prepare a sample for alpha counting in approximately six hours. Thus, the potassium fluoride fusion procedure has the advantage of being much quicker than the EPA procedure.