| 摘要 |
Substantially pure uranium hexafluoride is shipped in a conventional overpack. A cylinder includes a vessel with a cylindrical sidewall A head permanently affixed to the sidewall closes one end of the vessel. A valve controls the flow of matter into and out of the vessel. A sealing surface connected to the vessel surrounds the valve. A cap covers the valve and a pair of seals is located between the sealing surface and the cap. The volume between the two seals, the cap and the sealing surface defines a test volume. A test port connects the test volume and an exterior surface of the vessel, and fasteners press the cap against the sealing surface. A maximum rate of leakage from within the cap to the atmosphere outside the cap is determined by measuring the leakage rate into the test volume with a leak testing apparatus connected to the test port. Thereafter the cylinder is placed in a conventional overpack. The maximum leakage rate is determined using a test apparatus consisting essentially of a vacuum pump, a pressure gauge, a container of known volume, a valve to control the flow of air from the atmosphere into the container which are all adapted to be connected to the test port at the same time, a valve controlling the flow of gas from the container into the test volume, and a valve controlling the flow of gas from the test volume to the vacuum pump.
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