Feasibility Study Reviewing the Use of CO₂(G) as a Tracer Gas for Leak Detection in Generators

Abstract

Generator stator leak tests are performed during post-maintenance preparation to run-up procedures to mitigate hydrogen coolant leaks during operation. Existing leak detection practices utilize thin films and gas sniffers to detect tracer gas in an air based mixture. A feasibility study assessed the use of CO_2(g), as an alternative leak detection tracer, with new Optical Gas Imaging (OGI) Cameras. Non-nuclear industry Operating Experience (OPEX) identified that OGI provide improves leak detection over existing practices by allowing faster and more frequent inspection campaigns. OGI also provides more accurate leak location detection, especially from inaccessible or well ventilated areas. Use of OGI with CO_2(g) tracer in an operational hydrogen filled generator has been performed internationally, providing a new method for implementing online preventative maintenance. Specific application of OGI during stator winding leak tests promises a significantly quicker leak detection technique compared to traditional vent bagging and sniffing.