Study on Water Leak-Tightness of Small Leaks

The practical threshold for water leak-tightness of small leaks was determined by experimentation. Small leak samples were made and measurements were taken of the gas leakage rates and water leakage rates for the identical leak samples in order to identify the standardized leakage rate (Pa·m3 /s SLR) of a leak sample that did not permit water leakage. The results show that a leak hole corresponding to 10-5 Pa·m3 /s SLR does not permit water leakage under experimental conditions in this study. In addition, experiments with 1-inch cylinder valve leak samples made by scratching the valve stems were performed. This result assured that the criteria for the preshipment leakage rate test, 1x10-3 ref-cm3 /s, as prescribed in ANSI N14.5 is an appropriate value from the point of view of water leak-tightness for enriched uranium hexafluoride packages.