Application of video inspection in in-service inspection of anti-vibration bars for heat transfer tubes of AP 1000 steam generators

Anti-vibration bar (AVB) is located in the bend area of the heat transfer tube bundle of the steam generator (SG) of the nuclear power equipment. It is used to support the SG heat transfer tube bundle and suppress the flow-induced vibration of the tube bundle during operation, so as to ensure the safety of the heat transfer tube operation. According to the requirements of an AP 1000 nuclear power plant, in order to determine whether the status of AVB changed significantly compared to the time of installation, a video equipment meeting the technical requirements of detection was developed, video detection of AVB was carried out, and supplementary verification was provided for the "proximity tube signal" that may be found in eddy current detection of heat transfer tubes. The method was successfully applied in engineering practiced and provided some references for in-service inspection of the anti-vibration bars of the steam generator tubes in nuclear power plants.