Primary Heat Transport System Return To Service Following The Refurbishment Outage At The Point Lepreau Generating Station

摘要

During the latter portion of 2012, the Point Lepreau Generating Station (PLGS) was returned to service following a mid-life refurbishment that commenced in 2008. The plant achieved criticality following refurbishment on 2012 July 25 (30 years to the day of first criticality in 1982) and commercial operation re-commenced on 2012 November 23. During the plant refurbishment, the in-core portions of the Primary Heat Transport (PHT) system were replaced along with all 780 carbon steel feeder pipes. The out-of-core carbon steel headers and steam generators containing Alloy 800 boiler tubes were placed in a controlled lay-up state. This resulted in a refurbished PHT system that contained significant quantities of carbon steel and Alloy 800 that had seen prior service (～23 Effective Full Power Years) and were therefore oxide loaded with magnetite, along with new surfaces of 403/410 stainless steel and A106C carbon steel that required hot conditioning prior to beginning at-power operation. A hydrazine/dissolved-hydrogen-based hot-conditioning process was selected to enable protective oxide layers to be initiated on the new materials and to promote the in-situ reduction of the existing oxide films that may have been partially oxidised during the extended refurbishment outage. In order to monitor the effectiveness of the hot conditioning process, in addition to conventional chemistry monitoring, an on-line corrosion monitoring system was installed comprising a hydrogen effusion probe (HEPro) connected to outlet feeder C11. This paper describes the details of the chemistry control strategies used for the PHT system hot-conditioning and the results obtained from the chemical monitoring and the corrosion probe during the hot-conditioning process. The successful use of the online corrosion monitor to assess, in real-time, the hot-conditioning process was demonstrated. This assisted the station to progress the re-commissioning of the reactor and led to early establishment of specified chemistry conditions in the initial operation of the refurbished PHT system.