ML20080P079

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Suppls 840112 Response to Generic Ltr 83-41 Re Fast Cold Starts of Diesel Generators.Percentage of Starts for Surveillance & Maint Activities & Actual Demand Did Not Change Significantly for Semester Following 830531
ML20080P079
Person / Time
Site: Brunswick  Duke Energy icon.png
Issue date: 02/09/1984
From: Zimmerman S
CAROLINA POWER & LIGHT CO.
To: Vassallo D
Office of Nuclear Reactor Regulation
References
GL-83-41, NLS-84-061, NLS-84-61, NUDOCS 8402220430
Download: ML20080P079 (3)


Text

Cp&L Carolina Power & Light Company SERIAL: NLS-84-061 FEB 091984 Director of Nuclear Reactor Regulation At tentiva: -Mr. D. B. Vassallo, Chief Operating Reactors Branch No. 2 Division of Licensing United St ates Nuclear Regulatory Commission Washington, DC 20555

~ BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 FAST COLD STATUS OF DIESEL GENERATORS (GENERIC LETTER 83-41)

Dear Mr. Vassallo:

In a letter dated January 12, 1984, Carolina Power & Light Company (CP&L),

provided a partial response to part 1 of Generic Letter 83-41 for Brunswick Steam Electric Plant, Units No. I and No. 2 and committed to provide the reraaining information as soon as it could be compiled.

In the above letter, CP&L supplied your staf f with the total number of starts for each diesel generator from December 1, 1982 through November 30, 1983 and categorized these starts for the January 1, 1983 to May 31, 1983 time frame.

Carolina Power & Light Company has evaluated the categories of starts for the remaining months and has concluded that the percentage of starts for surveillance activities, maintenance activities, and actual demand did not

. change significantly for the semester following May 31, 1983.

Enclosure 1 provide you with CP&L's assessment of the effects of frequent fast cold starts on the diesel generator reliability and availability. Should you have any questions concerning this letter, please do not hesitate to contact a member of our Licensing Staff.

Yours very truly,

/

S. R. Zimmerma Manager Nuclear Licensing Section PPC/ccc (9442PPC)

En closures cc: :fr. D. O. Myers (NRC-BSEP)

Mr. J. P.'O'Reilly (NRC-RII)

Mr. M. Grotenhuis (NRC) 8402220430 840209 PDR ADOCK 05000324 P pm 80/f ;

'f l 411 Fayetteydle Street

  • P. O. Box 1551
  • Raleigh, N. C. 27602
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ENCLOSURE 1 RESPONSE TO ITEM 2 0F GENERIC LETTER 83-41

t (9442PPC/ccc)

The diesel generator engines at Brunswick are Nordberg model FS-131641SC. Th e lube oil system utilizes a filter and prelube which continually circulates oil

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at 145'F to 155*F through the engine crankcase for 40 minutes each hour when the engine is not running. In addition, a jacket water heater pump circulates water at 135*F to 150*F through the engine when not running. These features preclude " cold" starts from ambient temperature without prelubrication and warmup. We f eel that even with these features, f ast starts to rated load capacity at the frequencies required in the Technical Specification action and surveillance statements create cumulative deleterious effects on the engine through the following means:

1. Rapid engine accelerations and deceleration to and f rom rated speed produce excessive mechanical stress on vital engine parts contributing to component wear and f atigue.

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2. Carbon buildup in the combustion area and exhaust system components is excessive for engines experiencing repeated starts. The governor system drives the fuel racks to the full open position for the f ast start resulting in a rich fuel mixture and subsequent carbon buildup.
3. The lubrication properties of the lube oil change slightly as a result of the temperature effect on viscosity in the range of the temperature dif ferential between lube oil at startup (145'F-155'F) and at normal operating temperature (165"F). Fast starts at reduced lubrication properties contribute to mechanical wear on moving components as a result of increased friction.

The manifestation of these effects has been the common mode f ailure on all fout Brunswick diesels of one or more accessory pump dowel pins and cap screws in the flex drive coupling drive plate. Die f ailure occurred at 1659 engine starts and was a result. of metal f atigue of the dowel pin material due to the exceasive number of engine starts (see LER 1-82-78).

i While we bria experienced no other common mode failures, we feel that the fast starts significantly degrade the engine / generator reliability and availability by increasing the probability for single component failure. Isolated failures L of piston connecting rod bearing bolts, exhaust and inlet valve of seats, and fuel injector parts have occurred to date on the Brunswick engines. Failures of this type are not expected on stationary diepal engines, procured with rigid purchase specifications, having such relatively short run times (average 625 hours0.00723 days <br />0.174 hours <br />0.00103 weeks <br />2.378125e-4 months <br /> per engine).- The f ailures of the components can most likely be attributed to the ef fects of the fast starts followed by immediate loading to rated capacity as discussed above. The average nmiber of lifetime starts on the Brunswick diesels is 1632.

(9442PPC/ccc) t

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