INDUSTRIAL APPLICATION OF RESEARCH RESULTS OF PACKINGS ON SAFETY RELEVANT VALVES IN NUCLEAR POWER PLANTS

摘要

In a NPP approximately 380 safety relevant valves are installed. The main requirements are the safety and operational availability as well as a adequate leak tightness of the sealings and stem packings. Based upon the research results of the MPA-Stuttgart, Germany on packing features specific procedures for handling, assembly and maintenance of packings and analytical inputs for the design calculation have been developed. Depending on the valve size, especially on the stem diameter, the packing influences the necessary stem force for the closing and opening function due to the amount of friction force. The complying equations of the valve calculation guideline were derived from the research results and rely on covering material characteristics of the approved packing rings such as friction coefficient and the vertical/horizontal force transfer factor of the stressing force. The industrial application often requires a more detailed calculation and handling of the actually installed packing configurations especially if existing valves are considered for redesign measures and recalculation. Therefore additionally mock-up tests of existing packing configurations have been performed in cooperation with the packing manufacturer in order to get very specific material coefficients as input data for the calculations. This paper presents the application of research results to design calculation of safety relevant valves as well as the development of procedures for the packing assembly and maintenance..