VALVE STEM PACKING IMPROVEMENT STUDY.

BY EMPLOYING QUESTIONAIRES AND FACE-TO-FACE INTERVIEWS WITHVALVE AND VALVE PACKING MANUFACTURERS, AS WELL AS NUCLEAR PLANT PERSONNEL, AN UNDERSTANDING OF VALVE STEM PACKING LEAKAGE PROBLEMS FROM EACH OF THE THREE VIEWPOINTS WAS DEVELOPED.THIS INFORMATION, IN-HOUSE EXPERIENCE, AND AVAILABLE TECHNICAL LITERATURE WERE USED TO DEVELOP SPECIFIC RECOMMENDATIONSFOR VALVE MANUFACTURERS, VALVE PACKING MANUFACTURERS, AND NUCLEAR PLANT VALVE USERS. IT WAS GENERALLY RECOMMENDED THAT EACH OF THESE GROUPS MAKE BETTER USE OF GRAPHITE PACKING. THE QUESTIONNAIRES AND INTERVIEWS INDICATED THAT INCREASED USAGE OF GRAPHITE PACKING OVER THE LAST FEW YEARS HAS REDUCED THE INCIDENCE OF VALVE PACKING PROBLEMS. TO CONFIRM THIS, A SURVEY OF LICENSEE EVENT REPORTS (LERS) FROM 1972 TO 1980 WASUNDERTAKEN USING THE KEYWORDS ″ VALVE ″ AND ″ PACKING ″ . ASTATISTICAL ANALYSIS OF THE LER DATA CONFIRMS THAT THE ADOPTION OF GRAPHITE PACKING HAS SIGNIFICANTLY REDUCED VALVE STEM LEAKAGE.