Flow accelerated corrosion wear in NPPs with WWER-440 and WWER-1000 equipment components, pipelines and fittings

摘要

NPP's 'pipelines expose to Erosion & Corrosion Wear (ECW) during operation. Existence of the ECW exerts negative influence upon NPP safety? reliability and economical characteristics. Fulfilled measurement processing of equipment's elements and pipe's wall allowed to determine the value of ECW velocity. Thus there were two velocities calculated:the velocity of "getting thinner" of metal due to ECW during period from operating start till measuring moment, W{sub}1, mm/year;the velocity of thickness' difference (both thickening and getting thinner) for the period between two planned preventive repairs. W{sub}2, mm/year.Calculations made revealed that the values of W{sub}1, and W{sub}2, (practically W{sub}2> W{sub}1 always) are considerable different. While use of hydrazine- ammonian regime at NPP the ECW is accompanied with considerable deposits of iron combinations.Measurements with use of ultrasonic control reveal both the deposits' thickness and a thickness of non-corrosion metal. The report presents results O the wall thickness measurement processing at equipment's elements and pipes of NPP with WWER-440 andWWER-1000, velocity values of W{sub}1, and W{sub}2, ECW's analysis and factors defined the sort of metal damage.