Application of instrumental neutron activation analysis to the measurement of water tree growth in polymeric insulation

The sensitive technique of instrumental neutron activation analysis (INAA) has been used to measure the penetration of ions into the water treed regions of polymeric materials. The technique has been used to study water trees grown in the laboratory, using a water electrode and to examine the concentration of trace elements in an XLPE cable which failed in service. The study shows that ions penetrate into and beyond the visible water-treed regions. This leads to a quantifiable difference in the distribution of trace elements in the treed and untreed regions of the polymer-insulated cable examined. The possibility of applying INAA techniques to cable testing is discussed