ML20083C922

Applicant Exhibit A-13,consisting of to NRC Re Confirmation of Action Ltr

ML20083C922
Person / Time
Site:	Vogtle
Issue date:	04/17/1995
From:	Hairston W GEORGIA POWER CO.
To:
References
CAL, OLA-3-A-013, OLA-3-A-13, NUDOCS 9505230086
Download: ML20083C922 (5)

Text

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April 9, 1990 0FFICE Of SECRETARY I Ee '

w. a. s.i,. .m 00CKETING BRAHC &"@h sene ne eei.o.m w c w o ce<m ens ELV-01516 0012 Docket No. 50-424 U. S. Nuclear Regulatory Commission -

Region !!

101 Marietta Street, N. W.

Atlanta, GA 30323 ATTN: Mr. S. D. Ebneter

Dear Mr. Ebneter:

' V0GTLE ELECTRIC GENERATING PLANT CONFIRMATION OF ACTION LETTER On March 20, 1990, a site area emergency was declared due to a loss of offsite power concurrent with a loss of onsite emergency diesel generator capabil8ty. ,

Following the event, GPC received a Confirmation of Action Letter dated March i 23, 1990 concerning certain actions we were taking. We have reviewed the l March 20th event and the appropriate corrective actions necessary for entry into Mode 2 have been accomplished. Therefore, we are requesting approval to return Unit I to Moda 2 and subsequent power operation. The following discussion provides justification for this request.

In accordance with Vogtle Electric Generating Plant procedures, an event review team has investigated the events leading up to and following the site area emergency. The event review team has presented the results of it's review to management and those recoamendations considered important for continued safe plant operation have been implemented. These include establishment of a management >olicy on control and operation of vehicles (see attached letter from George Bock)old to site personnel); upgrading of emergency notification network communications (see attached letter from George Bockhold to Emergency Directors and Cosununicators); retesting and calibration of both Unit 1 emergency diesel generator control systems; temporary barricades to prevent unnecessary entry into low voltage switchyard areas; and communications of immediate corrective actions related to operations to licensed operators.

In addition, the event review team report also contains a number of longer-term recommendations which require additional management review and evaluation.

These include the sequencing of outage activities; plant conditions during mid-loop operations; post-maintenance diesel functional testing; emergency notification system upgrades; changing diesel generator control logic; and re-evaluating the duties and responsibilities of the Emergency Director.

9505230086 950417 DR ADOCK 0500 4 92 PROJECT 001623

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NUCLEAR REGULATORY COMMISSION re 9 a 9-o A 4 -1 DocketNo. fo var-oc4-1 Official Exh. No. '3 in the nutter of. Vo9 41e Lt a ' 4 5 1*1 Staff IEiNT!fCD /

Appi: cant 7 RECEIVED r inurvenor REJECTED Conro Ottr Con:ractor DATE O 'b i 7 - Q C Ottar Witness Ate (o y Reporter 7. 2 . l.'4 3 x . '

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GeorgiaPoner A U. S. Nuclear Regulatory Commission Region 11 ELV-01516 Paae Two The most significant occurrence during the event of March 20, 1990, involved the failure of Diesel Generator (OG) 1A to remain running to support shutdown cooling. Georgia Power Company, utilizing utility and vendor technical experts l has investigated the DG failure and has determined the following: '

a. During bench testing, all three Jacket water temperature switches were found to be set high during the OG maintenance inspection in early March 1990 (by approximately 6-10 degrees F above the setpoint). All three were adjusted downward using a calibration technique that may have differed from that previously used. i

b. Following the March 20 event, all three switches were again bench tested.

Switch TS 19110 was found to have a setpoint of 197 degrees F which was approximately 6 degrees F below its previous setting. Switch TS 19111 was I found to have a setpoint of 199 degrees F which was approximately the same i as the original setting. Switch T5 19112 was found to have a setpoint of {

186 degrees F which was approximately 17 degrees F below the previous.

setting and was readjusted. Switch TS 19112 also had a small leak which was judged to be acceptable to support diagnostic engine tests and was reinstalled,

c. During the subsequent test run of the DG on March 30, one of the switches (TS 19111) tripped and would not reset. This appeared to be an ,

intermittent failure because it subsequently reset. This switch and the leaking switch (TS 19112) were replaced with new switches. All subsequent t testing has been conducted with no additional problems.

d. The Unit 1 jacket water temperature switches have been recalibrated with the manufacturer's assistance to ensure a consistent calibration technique.

e. Subsequent testing indicated that the diesel annunicator indication of March 20, 1990 is reproduced on a high jacket water temperature trip.

f.

A test of the jacket water system temperature transient during engine starts was conducted. The purpose of this test was to determine the actual I jacket water temperature at the switch locations with the engine in a nomal standby lineup, and then followed by a series of starts without air rolling the engine to replicate the starts of March 20. The test showed that jacket water temperature at the switch location decreased from a standby temperature of 163 degrees F to approximately 156 degrees F and remained steady.

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GeorgiaPoner A U. S. Nuclear Regulatory Comission Region II ELV-01516 Paae Three

g. Since March 20, 1990, GPC has performed numerous sensor calibrations (including jacket water temperatures , extensive logic testing, special pneumatic leak testing, and multiple) engine starts and runs under various 1 conditions. Since March 20, the 1A DG has been started 18 times, and the 18 DG has been started 19 times. No failures or problems have occurred {

during any of these starts. In addition, an undervoltage start test 1 l

without air roll was conducted on April 6,1990 and the 1A D/G started and loaded properly.

Based on the above facts, we have concluded that the jacket water high tamperature switches were the most probable cause of both trips on March 20, 1990.

In addition, the following actions have been or are being implemented to ensure a high state of diesel reliability.

1. Operators are being trained prior to their next shift to ensure that they understand that an emergency reset will override the high jacket water temperature trip. Alars response procedures will be revised to address emergency reset functions prior to April 30, 1990.

2. The undervoltage start feature of the Unit 1 DGs has been modified such that the non-essential engine trips are bypassed. However, alarms are still provided to inform the operators of off normal conditions. (This change will be implemented on Unit 2 prior to April 30,1990.)

3. GPC is evaluating the possibility of a design change and Technical Specification change to delete the jacket water high temperature trip as an essential engine trip.

4. GPC has reviewed air quality of the D/G air system including dewpoint l control and has concluded that air quality is satisfactory. Initial reports l of higher than expected dewpoints were later attributed to faulty instrumention. This was confirmed by internal inspection of one air receiver on April 6,1990, the periodic replacement of the contol air filters last done in March,1990 which showed no indication of corrosion and daily air receiver blowdowns with no significant water discharge.

5. Based on discussions with the NRC in Atlanta on April 9,1990, GPC will finish reviewing the event review team's long term recomendations and will transmit a summary and schedule of the actions taken or to be taken to the NRC by May 15, 1990. The administrative >rocedures that specify control of vehicles in the perimeter area will also >e revised by May 15.

92 PROJECT 001625

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l Georgia P0her b U. S. Nuclear Regulatory Commission Region 11 ELV-01516 Paae Four

6. GPC will continue to work with the IIT and an independent lab to evaluate the instruments currently under quarantine. Upon completion of the the lab test, calibration procedures will be revised as necessary to ensure  ;

consistent performance.

Completion of these ' investigations, reviews, tests and corrective actions justify GPC's determination that the DG's are operable. GPC will continue to work with the Transamerica DeLaval Incorporated Owners Group to improve DG reliability. GPC will also review possi >1e improvements to protective instrumentation and controls.

Based on the above discussion, we have completed the appropriate corrective actions necessary to safely operate the unit. We request NRC approval to allow Unit 1 to return to operation.

Should you have any questions, please inquire.

Sincerely, N. . !$= M W. G. Hairston, III WGH,III/NJS/gm Attachment xc: Georaia Power Connany Mr. C. K. McCoy  ;

Mr. G. Bockhold, Jr.

Mr. R. M. Odos I Mr. P. D. Rushton )

NORMS '

l U. S. Nuclear Reculatory Commission l

Document Control Desk i Mr. T. A. Reed, Licensing Project Manager, NRR Mr. R. F. Aiello, Senior Resident Inspector, Vogtle 92 PROJECT 001626

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