Innovative Pipe Thickness Verification for Feedwater Flow at Darlington Nuclear Power Generating Station

Abstract

Darlington nuclear generating station (DNGS) uses externally mounted Ultrasonic Flow Meter (UFM) to verify its feedwater flow rate for the heat balance program. Recently a WANO operating experience (OPEX – WER ATL 14-0448) has identified an issue with the pipe thinning under the externally mounted UFM transducer area in PWR plants, consequently the flow correction factor had been slowly trending in the non-conservative direction. Therefore, DNGS needs to assess the implication of this OPEX and confirm if the pipe thinning is occurring beneath DNGS’s UFM brackets. This report is to summarize the action taken on the piping thickness measurements and the results in a cost effective way. Additional, the results are also verified with FAC (flow accelerated corrosion) monitoring data.