MEASUREMENT OF LEAKS IN HERMETICALLY SEALED CONTAINERS USING $sup 85$Kr
Two methods of using Kr/sup 85/ for leak detection are described. In the first method the containers are immersed in Kr/sup 85/ at a high pressure and during the immersion period gas is forced into those which leak. These are then removed and monitored individually for radioactive content. Leak rates as low as 10/sup -11/ standard ml/sec have been measured in this manner. Large numbers of small volume containers such as transistor encapsulations and thermionic valves are most readily inspected by this technique and its applicatlon to transisted quality control is discussed in detail. Some of the difficulties associated with the method, such as misinterpretation of very small leak rates due to surface contamination and of very large leak rates due to loss of gas before monitoring, are also considered. In the second method a small quantity of the gas is inserted before the final seal is made. A leak is detected by placing the container in a chamber which is evacuated amd then isolated. Gas which leaks out is collectetl and pumped into a counter and from the counting rate the leak rate is calculated. The method is most attractive for leak testing small numbers of large volume, thick walled contniners such as pressurized vessels and reactor fuel elements. A comparison is made with the helium mass spectrometer and it is concluded that the Kr/sup 85/ method is cheaper, simpler, more reliable, and in some cases more sensitlve. (auth)
- Research Organization:
- United Kingdom Atomic Energy Authority. Research Group. Wantage Research Lab., Wantage, Berks, England
- NSA Number:
- NSA-17-008489
- OSTI ID:
- 4723537
- Report Number(s):
- AERE-R-3704
- Country of Publication:
- United Kingdom
- Language:
- English
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