ML20071J438

Revised Page 4 to 790625 Inservice Insp & Test Program for Pumps,Valves & Pressure Tests

ML20071J438
Person / Time
Site:	Millstone
Issue date:	04/30/1982
From:	NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20071J432	List: A02327, Forwards Revised Page 4 to 790625 Inservice Insp & Test Program for Pumps,Valves & Pressure Tests, in Response to NRC 820226 Request ML20071J438
References
PROC-820430, NUDOCS 8204270256
Download: ML20071J438 (2)

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DOCKET NO. 50-336 ATTACllMENT 1 MILLSTONE NUCLEAR POWER STATION, UNIT No. 2 REVISION TO ISI/IST PROGRAM APRIL, 1982

Another important requirement to assure reliable bearing tenperature monitoring is that it be continuous, not periodic. Experience indicates that failing bearings whether anti-friction type or sleeve of ten exhibit fluctuations between normal and abnormal metal temperatures. A good example is the babbitt lined sleeve bearing which will initially experience a rapid rise in temperature and then return to normal temperatures af ter the bearing wipes and clearances open up causing increased oil flow. The abnormal temperature rise would most probably go undetected unless continuously monitored.

The monthly vibration signature analysis conducted by NNEC0 will detect bearing problems at a very early stage. At the onset of a bearing problem, low level vibration will be generated at characteristic frequencies depending on the nature of the problem. The low level vibration typically amounts to less than 1% of the overall vibration amplitude and therefore cannot be detected by a simple amplitude monitoring program conforming to IWP minimum requirements. However, the low level changes in bearing distress frequencies are routinely detected in the MP-2 signa-ture analysis program and analyzed to pinpoint the cause.

Alternate Testing P.ecord and analyze pump vibration signature. Signature will be measured as velocity spectrum over at least 8 times the rotational speed. S.ignatures will be evaluated using the acceptance criteria of Figure IWP-1. This monthly analysis will provide more meaningful analysis of pump bearing condition than annual measurement of bearing temperature.

ACCEPTANCE CRITERIA - FOR FIGURE IWP-1 Acceptable All values of the velocity signature fall within the " acceptable" range of Figure IWP-1 and the overall RMS value of the velocity signature is less than 6VdB above the baseline signature.

Alert Any value of the velocity signature which falls within the " alert" range of Figure IWP-1 or the overall RMS value of the velocity signature increases by more than 6VdB.

Required Action Range Any value of the velocity signature falls within the " required action" range of Figure IWP-1 March 29, 1982

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