Judgment leakage

Analysts should review the technical basis for uncertainties in the measurements. They should develop judgments for the uncertainties based on the plant experience and statistical interpretation of plant measurements. The most difficult aspect of establishing the measurement errors is estabhshing that the measurements are representative of what they purport to oe. Internal reactor CSTR conditions are rarely the same as the effluent flow. Thermocouples in catalyst beds may be representative of near-waU instead of bulk conditions. Heat leakage around thermowells results in lower than actual temperature measurements. 

There are defect limits that are associated with random failure modes. For example, if there is a leak from a mechanical seal on a pump, where do we decide that the leakage is excessive and requires immediate maintenance Vibration analysis severity levels are also typical examples of when do we have severe enough conditions to warrant equipment shutdown and overhaul. In such circumstances, the defect limit is dependent upon individual subjective judgment. 

Criteria for leak classification and leakage control are provided in Tables VII-5.3A, VII-5.3B, and VH-5.3C. The examples of leak conditions provided in the tables are presented as guidelines and are not exclusive. The judgment of the operating company personnel at the scene is of primary importance in determining the grade assigned to a leak. 

If the actual amount of leakage is critical to a given application, the manufacturer can usually simulate the service conditions and give a more accurate and meaningful test. It is necessary, however, to justify the increased cost of this test work. For most applications, the ANSI test criteria provide an adequate technical base for judgment. 

The oxygen par tlal pres sure of 16 0 mm Hg was chosen to assure crew comfort and efficiency. The compartment altitude of 15,000 ft is an optimization among crew total pressure requirement, fire hazard caused by high oxygen concentration in the compartment atmosphere, and compartment leakage considerations. This optimization cannot be determined exactly because of the human factors and the fire hazard question involved. It becomes largely a matter of judgment as to the final conditions chosen. 

In addition, leakage of primary coolant is continuously monitored by sodium leak detectors as in-service inspection to confirm the integrity of the coolant boundary. These facts lead to the following judgments ... 

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