Valve stem packing improvements: Final report

Valve stem seal leakage has been the direct cause of a significant number of events which resulted in the shutdown of nuclear power plants. It has also been a major contributor to the maintenance effort required in these power plants. The overall objectives of this project were to: identify the root causes of selected events related to improper performance of valve stem seal systems, develop the means to permanently correct the performance deficiencies, evaluate the corrective actions in full-scale laboratory testing and in-plant evaluations, and provide for the technology transfer of the recommended corrective actions. Specific achievements detailed in this report include: the development of valve stem sealing systems that effectively control valve stem leakage, an extensive laboratory evaluation of these improved systems at full scale under simulated plant conditions, an extensive testing program to evaluate both the need for and relative effectiveness of corrosion inhibitors, and installation of the improved valve stem sealing system in an operating plant. The project was conducted in two phases. The activities and results of Phase 1 are published in EPRI Report NP-4255 (February 1986). This final report includes the activities and results of both Phase 1 and Phase 2.