Improved nuclear LP turbine inspection strategy -- A team approach

This paper describes the impact of nondestructive examination (NDE) of turbine wheel dovetails and shrunk on wheel interfaces to the power generation provider. The performance of these inspections is crucial to ensure safe and reliable uninterrupted service of power generating equipment. The results of these inspections impact recommended reinspection intervals based on initial flaw sizes, material properties and equipment operation. Current technology in inspection practices has provided for new solutions that support optimization of recommended planned outage intervals. A case study is provided which details the combined team effort of customer, consultant, and original equipment manufacturer (OEM) to improve the process of inspection and data evaluation in order to provide appropriate resolution of the test results. Advances in ultrasonic test imaging and flaw sizing techniques were used to evaluate standard flaw default values assigned to turbine wheel keyways. Structural assessment of the corrected flaw default sizes and consideration of equipment operation, including turbine preheating, served to extend the reinspect cycle to 6 years