Measurement of nuclear reactor neutron flux with glass track detectors

Abstract

ABSTRACT Integrated reactor neutron flux must be measured when samples to be dated or to be analysed for uranium content are irradiated with neutrons in nuclear reactor. A method has been suggested to measure the integrated reactor neutron flux by counting the track density on a glass surface and before and after etching determining the change of thickness of the glass which is irradiated together with the analysed samples. This method is based on the fact that the track density increases linearly as the thickness of the glass decreases during the first stage when the tracks were being etched. Two parameters (glass constants) have been defined for glass track detectors according to the analysis of the behaviour of the track density. Two kinds of glasses have been calibrated in nuclear reactor core with known integrated neutron flux. The glasses can be used to measure the neutron flux ranging from 1014 to 1018 n/cm2 with an accuracy of about ± 7%. The measurements of reactor neutron flux with these glasses and with cobalt activation foils are in good agreement. The advantages of the calibrating method are: it is easy to perform and can provide sufficient quantity of glasses after calibrating only once. The method of calibrating glasses is also presented.