Determination of Sr-90 in liquid power-plant wastes.

The topic of this paper is the method, results and experiences of Sr-90 analysis performed on aqueous radwaste samples from the NPP Paks. The analysis is based on a combined separation method, which results in the separation and detection of radiostrontium (Sr-89 and Sr-90) and or Y-90. After suitable pretreatment of the samples, radiostrontium is concentrated using a Sr.Spec(R) chromatographic column. The eluted radiostrontium is precipitated in thin layer and its activity measured in low-background, gamma-ray compensated alpha-beta detector. The chemical yield is determined by AES. The Y-90 activity of the samples is also measured using the procedure described elsewhere. This is based on the selective adsorption properity of the yttrium-ammonium-oxalate and yttrium-oxalate double salt mixture towards yttrium. In proper conditions (pH, oxalate anion activity, mass ratio of the salts) quantitative yield of Y-90 can be achived which is determined using Y-88 internal standard. As a result, the radioactive concentration of Sr-90 in the samples could be calculated. It was concluded that Sr-89 was not present in the samples, which is due to the relatively long (years) storage life of these samples.