Determination of radioactivity of concrete samples with transversal direction of the biological shield of the ASTRA - reactor Seibersdorf

A method to determine the radioactivity of samples from the biological shield of research reactors (ASTRA - reactor Seibersdorf) was developed. Drill core samples exhibit a special radioactivity direction, because research reactors have two different radiation sources. The samples activation through the beam holes is 1000 times higher than the activation through the reactor core. Samples with a cylindrical form were taken from the concrete shield and activated with longitudinal and transversal radioactivity direction. The radioactivity direction of the sample was determined trough the position in the shield and lateral measurements. Afterwards the radioactivity in the sample was determined with help of a reference method. Finally the samples were homogenized in order to eliminate the orientation and again the radioactivity was measured. These new values were used as a control for the first results. Only samples with transversal direction were considered in this report. (nevyjel)