A Simplified Method to Create Quantitative, "Fixed" Uranyl-Contaminated Metal Coupons

A method was developed and validated to quantitatively apply and "fix" uranyl contamination onto a metal surface (steel). Simple approaches are needed to create test surfaces in order to quantify contaminant removal or "decon" methods. We used steel discs sized to allow direct and accurate alpha counting in a Ludlum scanner from radioactive contaminants. A typical 3.8-cm-diameter coupon had a depleted uranyl loading of about 0.1 mg U cm^-2 with a count of 980 dpm. The resulting alpha radiation was measured with a precision of >97% for the same coupon. The alpha concentration on replicate coupons differed by as much as 9% (standard deviation). This method, based on earlier methods, required a uranyl solution to be dried but lowers the baking temperature to less than 100°C to increase safety in a typical radiological laboratory. A dike was used to provide a uniform coating of the uranyl solution.