ML20128Q938

Summarizes 961008 Meeting W/Util in Region II Ofc for Briefing on Circumstances Surrounding Failure of Switchyard Potential Transformer on 961015.W/list of Attendees & Handouts

ML20128Q938
Person / Time
Site:	Sequoyah
Issue date:	10/09/1996
From:	Lesser M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:	Kingsley O TENNESSEE VALLEY AUTHORITY
References
NUDOCS 9610210231
Download: ML20128Q938 (15)

Text

I October 9, 1996 I

Tennessee Valley Authority ATTN: Mr. Oliver D. Kingsley, Jr.

President, TVA Nuclear and Chief Nuclear Officer 6A Lookout Place 1101 Market Street Chattanooga, TN 37402 2801

SUBJECT:

MEETING

SUMMARY

- SEQUOYAH NUCLEAR PLANT, DOCKET NOS. 50 327, 50 328

Dear Mr. Kingsley:

On October 8,1996, at the request of the licensee, the NRC staff met at the Region II office with representatives of the Tennessee Valley Authority's Sequoyah Nuclear Plant staff. The purpose of this meeting was for the licensee to brief the NRC staff on the circumstances surrounding a failure of a switchyard potential transformer on October 5, 1996. The licensee provided details surrounding the failure, immediate actions taken, short term and long term switchyard program changes. The NRC issued Preliminary Notification 2 96 69 for this failure on October 7, 19.';. is a list of the individuals who attended the meeting, and contains a copy of the material supplied by the licensee at the meeting.

In accordance with Section 2.790 of the NRC's " Rules of Practice," Part 2.

Title 10 Code of Federal Regulations, a co)y of this letter and its enclosures will be placed in the NRC Public Document Room.

Should you have any questions concerning this letter, please contact us.

Sincerely, OriginalSigned by M.S.Lasser Mark S. Lesser, Chief Reactor Projects Branch 6 j

Division of Reactor Projects Docket Nos. 50 327, 50-328 License Nos. DPR-77, DPR 79

Enclosures:

1. List of Attendees

2. Handout Material cc w/encls:

(See page 2)

[

9610210231.961009 PDR; ADOCK 05000327 P

PDR r

TVA 2

cc w/ encls:

Mr. O. J. Zeringue, Senior Vice President Mr. Ralph H. Shell, Manager Nuclear Operations Licensing & Industry Affairs Tennessee Valley Authority Sequoyah Nuclear Plant 6A Lookout Place Tennessee Valley Authority 1101 Market Street P. O. Box 2000 Chattanooga, TN 37402 2801 Soddy Daisy, TN 37379 Dr. Mark 0. Medford, Vice President Mr. Michael H. Mobley, Dir.

Engineering and Technical Services Div., of Radiological Health 6A Lookout Place 3rd Floor. L and C Annex 1101 Market Street 401 Church Street Chattanooga, TN 37402 2801 Nashville, TN 37243 1532 Mr. R. J. Adney, Site Vice President County Executive Sequoyah Nuclear Plant Hamilton County Courthouse Tennessee Valley Authority Chattanooga, TN 37402 2801 P. O. Box 2000 Soddy Daisy, TN 37379 Distribution w/encls:

(See page 3)

General Counsel Tennessee Valley Authority ET 11H 400 West Summit Hill Drive Knoxville, TN 37902 Mr. R. R. Baron, General Manager Nuclear Assurance & Licensing 4J Blue Ridge 1101 Market Street Chattanooga, TN 37402 2801 i

2 Mr. P. Salas, Manager Licensing and Industry Affairs Tennessee Valley Authority 4J Blue Ridge j

1101 Market Street Chattanooga, TN 37402 2801 1

9 4

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.TVA 3-i Distribution w/encis:

E. W. Merschoff.-RII-M..S. Lesser RII S. E. Sparks, RII l-F. J.-Hebdon, NRR R. W. Hernan, NRR l

H. L. Whitener, RII C. F. Smith,-RII D. H. Thompson, RII J. H. Moorman, RII D. W. Jones,-RII PllBLIC NRC Resident Inspector-U. S. Nuclear Regulatory Commission 2600 Igou Ferry.

Soddy Daisy, TN 37379 i'

NRC Resident Inspector i

U. S. Nuclear Regulatory Commission l

1260 Nuclear Plant Road i

Spring City, TN 37381 1

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LIST OF ATTENDEES NRG

- S. D. Ebneter, Regional Administrator -Region II-(RII)~

- L. A. Reyes, Deputy Regional Administrator, RII J. R. Johnson, Acting Director, Division of Reactor Projects (DRP), RII

. M. S. Lesser, Branch Chief, Reactor Project Branch 6. DRP, RII S. E. Sparks Project Engineer, DRP, RII C. A, Casto, Engineering Branch Chief Division of Reactor Safety (DRS), RII H. 0.-Christensen, Maintenance Branch Chief, DRS, RII H. L. Whitener, Reactor Inspector, Maintenance Branch, DRS, RII P. J. Fillion, Reactor Inspector, Engineering Branch, DRS, RII

. R. W. Hernan, Senior Licensing Project Manager, NRR (telecon)

Licensee' Attendees:

J. T. Herron, Plant Manager, Sequoyah R. H. Shell, Site Licensing Manager T. A. Flippo. Site Support Manager D. C. Craven, Transmission and Power Supply Manager s

4

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Tennessee Valley Authority Sequoyah Nuclear Plant TVA/NRC Meeting Switchyard Status October 8,1996 i

i

Sequoyah Nuclear Plant Switchyard Status October 8,1996 Agenda Introduction R. H. Shell October 5,1996 Potential Transformer Failure D. C. Craven Switchyard Program Changes D. C. Craven Review of Actions Taken/In Progress D. C. Craven Closing J. T. Herron

F e

Sequoyah Nuclear Plant Switchyard Status October 5,1996 Event

- Failure of potential transformer (500 kv bus 1, section 2)

- 500 kv bus differential relay operation

- Combustible gases rose to intertie feeders 1

- 500/161kv intertie bank overcurrent relay operation Immediate actions taken/ recovery

- Potential transformer replacement

- Repair / restoration of bus

- Failure Evaluation Team in progress

- All corrective and preventive maintenance to be completed

I e

Sequoyah Nuclear Plant Switcayard Status Quality Improvement Team formed following the December 1995 plant trip TVA has recently implemented significant organizational changes to provide better control of nuclear plant switchyard activities

- A single point of management focus has been assigned

- A Transmission and Power Supply (TPS) manager has been assigned to each nuclear site, functionally reporting to the site maintenance manager

- Switchyard responsibility is now in the same organization with its engineering technical support i

O Sequoya:1 Nuclear Plant Switchyard Status Additionally, several major initiatives have commenced

- Switchyard design review

- A ' vertical slice' of one offsite power feed into the plant

- A recent independent management oversight review Initiation of a Reliability Improvement Plan for the switchyards

- Initial EPRI survey of the Sequoyah switchyards and transformers Additional management focus is being placed on the switchyard activities

i Sequoyah Nuclear Plant Switchyarc Status Actions taken since August 1996

- Briefing in Daily Status Meeting by TPS Supervisor

- Incorporation of switchyard activities into the daily schedule

- Appointment of Senior site manager to oversee switchyard improvement activities (routine schedule review meetings)

Evaluation of outstanding preventive / corrective maintenance items.

in switchyards (" white / yellow / red" chart) i

e Sequoyah Nuclear Plant Switchyard Status Actions completed since August 1996

- Four of five 161kv motor-operated disconnect (MOD) radius arm problems corrected

- PCB 5018 and line relays tested

- CCVTs on WBN Unit 2 and bus 2 section 2 tested

- Several hotspots on 161kv MODS and 500kv wavetrap connection found and corrected

- Replacement of main bank transformer cooling fan motors with new design initiated

- CSST B maintenance outage completed

- PCB 1008 for 161kv capacitor bank restored

- Sudden pressure relay protection to Unit 1 main bank transformers restored

<date/ time >

I

Sequoyah Nuclear Plant Switchyard Status Switchyards (Units 1 and 2) now classified as 10CFR50.65(a) (1) under Maintenance Rule due to exceeding goals

- Threshold of switchyard goal lowered / standards raised

- Now trending any switchyard challenges Maintenance Rule goal for switchyard

- FY '97 first quarter 4

- FY '97 second quarter 4

- FY '97 third quarter 3

- FY '97 fourth quarter 2

- FY '98 first quarter 1

Sequoyah Nuclear Plant Switchyard Status July 1,1996 - September 30,1996 - Five challenges (Maintenance Rule 10CFR50.65 (a) (1) Category)

- Power Circuit Breaker (PCB) 998 air system

- PCB 998 air system

- PCB 998 current transformer (CT) failure

- Mod 995 overheating 1

- PCB 5018 wavetrap "hotspot"

~

Sequoyah Nuclear Plant i

Switchyard Status Long-term corrective actions

- Completion of outstanding preventive maintenance items

- Acceleration of three Hitachi air-blast breaker replacement

- Acceleration of replacement of PCB 974

- Systematic replacement / rebuilding of obsolete high maintenance air l

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