Determination of the radioactive concentration of 90Sr in soil

A standardized method was developed to determine the radioactivity of 90Sr in soil based on the activity measurement of equilibrium amount of 90Y daughter isotope. After the wet destruction of the sample, strontium and yttrium ions are precipitated with oxalate ions. The precipitate is dissolved with cc. HNO3. Yttrium ions are selectively extracted from alkaline earth metal ions with TBP. The reextracted yttrium is precipitated with oxalate ions and the beta-radiation of the 'infinitely thin' layer is measured by a low-background beta-counter. (V.N.)