C. Söderström1 , J.L. Kastlander1 , P. Lagerkvist1 , S. Jonsson1
1Swedish Defence Research Agency (FOI)
Abstract:
As a complement to measurement of radioactivity in air, collection and measurement of radioactivity in deposition is performed within many national surveillance systems. Deposited radioactivity can give an estimate of external dose to the public and can also be used to calculate transport factors for radionuclides. The system used in Sweden consists of a collection funnel, from which the precipitation is passed through an ion-exchange column. The contents of the column are ashed and measured by gamma spectroscopy to determine deposited radioactivity. In order to have control of the method used within the national surveillance system, and a possible future modification of the method, the collection efficiency of the ion exchange columns has been investigated together with tests of a new ion exchange resin. The effects of ashing at different temperatures have also been investigated for the two types of ion exchange columns. The collection efficiency was high for all tested nuclides. For most nuclides, losses during ashing were small, but loss of iodine could be seen at temperatures as low as 60 °C. Deposition of Ru-106 during autumn 2017 revealed that activity can remain in the funnel and lead to cross-contamination of subsequent samples.
