ML18106A177

Special Rept 97-15,on 971022,2A EDG Declared Inoperable. Caused by Moisture Build Up in Starting Air headers.2A EDG Equipment Inspected Just Subsequent to Aborted Start

ML18106A177
Person / Time
Site:	Salem
Issue date:	11/21/1997
From:	Bakken A Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
97-15, LR-N970729, NUDOCS 9711280196
Download: ML18106A177 (5)

Text

e CPS~G Public Service Electric arc Gas ~~Mpary ?.O. Box 236 Har.coci<.s Bridge. Ne-,*, Je~sey 08038-0236 Nuclear Business Unit NOV ;:; 1 .:' .J l LR-N970729 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 SPECIAL REPORT 311/97-015-00 SALEM GENERATING STATION - UNIT 2 FACILITY OPERATING LICENSE NO. DPR-75 DOCKET NO. 50-311 Gentlemen:

This Special Report regarding a valid failure of the 2A Emergency Diesel Generator is being submitted pursuant to the requirements of Technical Specification 4.8.1.1.4.

Sincerely,

~~

A. C. Bakken Ill General Manager Salem Operations Attachment I- I.

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SPECIAL REPORT 3111-015 LR-N970729 PLANT IDENTIFICATION Salem Generating Station - Unit 2 Facility Operating License No. DPR-75 Docket No. 50-311 DESCRIPTION OF OCCURRENCE On 10/22/97 2.'\ Emergency Diesel Generator (EOG), an ALCO 251 engine, was being started in accordance with monthly surveillance test S2. OP-ST. DG-0001.

Approximately 6 seconds into the start sequence the operators decided that the start did not sound like a normal start sequence. At this point the operators manually interrupted the start sequence of the diesel. The engin~ was stopped before the over crank circuit of 10 seconds stopped the engine. The diesel was then declared inoperable.

PLANT CONDITIONS:

Unit 2 was operating in Mode 1 at approximately 100 % power. 28 and 2C ED G's were operable at the time of 2A EDG's failure to start.

REPORTING REQUIREMENT:

This failure is being reported as required by Technical Specification 4.8.1.1.4 which states:

"All diesel generator failures, valid or non-valid, shall be reported to the Commission in a Special Report pursuant to Specification 6.9.2 within 30 days.

Reports of diesel failures shall include the information recommended in Regulatory Position C.3.b of Regulatory Guide 1.108, Revision 1,. August 1977.

If the number of failures in the last 100 valid. tests (on a per nuclear unit basis) is greater than or equal to 7, the report shall be supplemented to include additional information recommended in Regulatory Position C.3.b of Regulatory Guide 1.108, Revision 1, August 1977."

SPECIAL REPORT 311,-015 LR-N970729 REPORT DETAILS:

The following information is provided as specified in Regulatory Position C.3.b of regulatory Guide 1.108, Revision 1, August 1977:

1. Diesel Generator Unit Involved: 2A

2. Number of Failures in the Last 100 tests:

a) This was the fourth failure of the 2A EDG in the last 100 valid tests of the 2A EOG.

b) This was the first failure of a Unit 2 EOG in the last 100 valid tests of the 2A, 28, and 2C EDG's in total. .

3. Cause of the Failure:

The cause of the unusual starting sequence could not be determined by testing and/or inspections. The diesel restarted properly on three subsequent attempts.

The most likely causes of the abnormal noise during the start sequence were: (1) moisture build up in the starting air headers; and/or (2) improper operation of the #3 air start motor. The moisture was probably due to operation of the air compressors to overcome leak-by of the fuel rack booster pressure regulators. This moisture could have caused sluggish operation of the fuel rack boosters and/or the air start solenoid valves with possible resultant improper air start motor operation. The improper air start motor operation may have been caused by grease on the bendix gear screw.

4. Corrective Measures Taken:

Note: Corrective actions were performed in the sequence listed below.

a) The 2A EDG equipment was inspected just subsequent to the aborted start . Fuel rack position, air start motor condition, fuel supply isolation valve position, speed recorder indication and annunciation received were all as expected. The floor under the air start motors .showed some sign of "liquid splash" although none of the people involved with the post trip inspection noted the floor as wet.

b) The fuel rack boosters were tested and operated properly, although there was some moisture noted when one side was operated.

c) The air start motors were tested. # 1, #2 & #4 motors operated properly on the first try, while# 3 motor required two attempts to engage. Lack of engagement of one air start motor will not prevent a successful start. The most likely cause for the failure of

SPECIAL REPORT 311.-015 LR-N970729

1. 3 air start motor to engage*was grease on the bendix drive. The air start motors on the other five EDG's were inspected and deposits of grease were not evident.

d) Approximately 1/2 ounce of water was drained from each fuel rack booster pressure regulator. While 1/2 ounce of water is not significant, it is an indication that moisture was present in the system.

e) The 2A EOG was re-tested satisfactorily as was expected, given the findings of a through c.

f) The 2A EOG fuel rack booster pressure regulators were replaced, thus eliminating the continuous air leak-by and resultant moisture.

g) The other two Unit 2 EDG's were tested satisfactorily to ensure their operability.

• h) The rack booster regulators on the other five Salem EDG's were checked for accumulated water. None was noted. Also none of the other regulators exhibited leak-by.

i) As a preventative measure, the rack booster pressure regulators on Unit 1, 18 and 1C EDG's will be replaced with a newer designed pressure regulator.

j) As a preventative measure, the rack booster pressure regulators on Unit 2, 28 and 2C EDG's will be replaced with a newer designed pressure regulator.

k) The fuel rack lubrication procedure will be revised to include draining of the booster pressure regulators during rack lubrication. Fuel rack lubrication is performed monthly.

I) The 2A EOG will be started weekly four times to assure no repeat failures. At the submittal of this report three of these "weekly" starts have been successful.

m) The 2A EOG air start motor bendix drives were cleaned and lubricated. A procedure revision will be made to clarify the cleaning, inspection and lubrication of the air start motor bendix drive.

n) The event will be evaluated for training impact.

5. Length of Time the Emergency Diesel Generator Was Cut of Service:

a) The 2A EOG was out of service for investigation of the 10/22/97 failure to start for 10.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

SPECIAL REPORT 311,015 LR-N970729

6. Define the Current Surveillance Test Interval:

a) The 2A EOG is in a 31 day surveillance test frequency as required by TS 4.8.1.1.2a.

This interval is required following one failure or less in the last twenty valid tests on a per diesel generator basis. This is the normal test frequency.

SAFETY CONSEQUENCES AND IMPLICATIONS At the time of the 2A EOG failure to start, the other two EDG's were operable. With one diesel inoperable, the two remaining diesels are capable of providing power to the minimum safeguards equipment required for analyzed .accident and transient

• conditions. Therefore, this event did not impact the health and safety of the general public.