Determination of the Strontium-90 concentration in soils and sediments

The Nuclear Regulatory Authority in Argentina carries out environmental radiological monitoring as part of its control tasks at the country's nuclear facilities. This monitoring is carried out independently of the monitoring that each facility must carry out and is used to verify the results reported by them. Within the framework of the Environmental Radiological Monitoring Plan of the Nuclear Regulatory Authority, samples are taken from different matrices such as water, plants, fish, sediments from surface water courses and samples from the soils near the facilities. One of the radionuclides whose presence is regularly monitored in the environment is strontium 90. This radionuclide is a fission product; it can be produced by emissions in accidental situations or found in the environment due to nuclear tests carried out in the past. The objective of this work is to describe a method applied to determine the concentration of strontium-90 activity in soils and sediments, by means of the organic phase extraction of its daughter, yttrium-90, and subsequent measurement of the Cerenkov effect in a liquid scintillation equipment. Said procedure makes it possible to obtain an appropriate detection limit, with a high chemical yield.