Acoustic monitoring of discharging and charging of fuel elements

Load variations during the discharging and charging operation emanate from mechanical contacts with adjacent elements. These contacts lead to measurable noise emissions. The correlation between load variation, fuel element lift and incidence of noise produces guidelines as to the type, intensity and location of these contacts leading to damage to the spacer. Each fuel element, without additional passage of time, is evaluated in accordance with five criteria. Optical inspections, which are very time consuming, can be carried out in this way arranged according to type and extent. In order to translate the method into practical use, a fuel element charging and discharging control system has been developed and this has been successfully applied since the major maintenance operation in 1984. (orig.)