ML20204D650

Forwards Addl Info Re Generic Ltr 83-28,Items 4.2.1 & 4.2.2,per 880624 & 30 Telcons Regarding Plant Periodic Maint Program for Reactor Trip Breakers (Rtbs) & Trending of Rtb

ML20204D650
Person / Time
Site:	Sequoyah
Issue date:	10/19/1988
From:	Gridley R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
GL-83-28, NUDOCS 8810210191
Download: ML20204D650 (6)

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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 374of n

SN 1578 Lookout Place

.00T 191988 U.S. Nuclear Regulatory Commission ATTN: Document Control Deck Washington, D.C. 20555 Gentlement In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - ADDITIONAL INFCRMATION FOR GENERIC LETTER (GL) 83-28 ITEMS 4.2.1 AND 4.2.P.

References TVA letter to NRC dated November 7, 1983 This letter provides NRC the additional informati>n that was requested in telecons between J. Donahew and B. Kimsey held on June 24, 1988 and June 30. 1988 regarding SQN's periodic maintenance program for the reactor trip breakers (RTBs) and trending of the RTB parameters to forecast any degradation that could affect operability of the RTBs. NRC requested this information to assist them in completing their evaluation of the SQN RTB periodic maintenance program to corroborate that it complies with requirements of GL 83-28, items 4.2.1 and 4.2.2.

Enclosed is a list of NRC's questions and TVA's response. Each question has been reviewed by TVA and confirmed to be addressed by the current SQN 4 RTB maintenance program, which is in compliance with the Westinghouse Electric Corporation (W) Maintenance Program Manual (MPM),

"MPM-WOGRTSDB50-01 for Westinghouse type DB-50 Reactor Trip Circuit Breakers and Associated Switchgear," dated November 20, 1986.

Please direct questions concerning this issue to B. A. Kimsey at (615) 870-6847.

Very truly yours, TENNESSEE VALLEY AUTHORITY

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R. Gridley, anager Nuclear Licensing and Regulatory Affairs 02 Enclosure 1 cc See page 2 0910210191 881019 PDR ADOCK 05000327 P PDC An Equal Opportunity Employer

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cc.(Enclosure):

, RMs. S. C. Black, Assistant Director for Projects TVA Projects Division l U.S. Nuclear Regulatory Commission  !

One White Flint, North 11555 Rockville Pike

• Rockville, Maryland 20852 '

l Mr. F. R. McCoy, Assistant Director for Inspection Programs ,

TVA Projects Division 1

U.S. Nuclear Regulatory Commission 7 Region II  !

101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 33323 l Sequoyah Resident Inspector .

Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 t

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9 F ENCLOSURE I. Item 4.2.1 - Periodic Shintenance Program for RTBs NRC Questions:

A. Does the SQN units 1 and 2 periodic maintenance program, for the RTBs include, on a 6-month basis:

Note: Maintenance Instruction (MI) 10.9.1, "Reactor Trip Breaker Type DB50 and Switchgear Inspection Associated with System 99," and MI-10.9.2, "Bypass Trip Breaker Type DB50 and Switchgear Inspection Associated with System 99," have been revised and are in compliance with the W MPM, MPM-WOGRTSDB50-01, for W type DB50 RTBs and associated switchgear. As provided in section 4 of the W MPM, scheduled maintenance on the RTBs and bypass trip breakers (BTBs) is to be performed a maximum of 18 months. NRC's questions are based on the W MPM dated October 14, 1983, which required that maintenance be performed on these items on a 6-month basis.

Therefore, the answers to these questions will be based on the current SQN RTB and BTB maintenance instructions, which are in compliance with the later revision of the W MPM dated November 20, 1986.

1. Verification of trip bar freedom.

2. Verification of operating mechanism alignment and freedom, using the procedure identified in the W program.

3. Retaining ring verification 33 places.

4. Verification of nut and bolt tightness.

5. Verification of pole bases physical condition.

6. Verification of arcing and main contacts physical condition, using the procedure identified in the W program.

7. Verification of insulating link's physical condition.

8. Verification of wiring insulation and termination physical condition.

9. Verification of arc chute physical condition.

10. Verification of breaker cleanliness.

11. Undervoltage Trip Attachment (UVTA) dropout voltage test and lubrication, using the procedure identified in the W program.

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, 12. Shunt Trip Attachment (STA) operation verification.

13. Verification of operation of auxiliary switches.

14. Inspection of positioning lever condition, using t,he procedure identified in y program.

15. Functional test of the breaker before returning it to service, using the procedure identified in the y program.

B. Does the SQN units 1 and 2 periodic maintenance program for the KTBs include, on a refueling interval basis:

1. Verification of cell interlock operation.

2. Examination and cleaning of breaker enclosure.

3. Measurement of trip force required, using the procedure identified in the y program.

4. Breaker respotee time for undervoltage trip.

5. Functional test of the breaker before returning it to service, using the procedure identified in the y program.

TVA Response for the above questions regarding GL 83-28, item 4.2.1.

TVA has reviewed the current SQN RTB and BTB procedures (MI-10.9.1 and MI-10.9.2 respectively) to confirm each of these questions have been addressed in accordance with the y MPM dated November 20, 1986. All of these items are addressed within each of these procedures and are performed on an 18-month interval. Furthermore, provisions are made in both mis to replace the UVTA and STA if either has been in service for 60 months or more or if the test data obtained during maintenance continuously remains outside the acceptance criteria for either the UVTA or STA.

II. Item 4.2.2 - Trending of RTB Parameters to Forecast Degradation of Operability As stated by NRC, four parameters have been identified as trendable and are included in the criteria for evaluation. These are:

1. undervoltage trip attachment voltage

2. trip force

3. breaker response time for undervoltage trip 4 breaker insulation resistance

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NRC further stated, "The licensee is to commit to inclusion of trip force, breaker response time and dropout voltage for undervoltage trip and breaker insulation resistance as trending parameters. The licensee j should also identify the organization which will perform trend analysis,  ;

how often the analysis will be performed and how the information derived

• i from the analysis will be used to affect periodic maintenance."

TVA's response for Item 4.2.2, "Trending of Reacto"r Trip Breaker Parameters to Forecast Degradation of Operability," is as follows. ,

In the reference letter, TVA acknowledged that a program for trending

• parameters was recommended in the technie.:1 standard on RTBs. TVA also l stated in the reference letter that thu recommendations from the l technical standard would be used at SQN to develop a program for trending '

parameters to assess any possibility of performance degradation. I Scheduled maintenance of the individual RTBs is initiated by use of preventative maintenance (PM) procedures. The respective PM is

, automat 1cally initiated at the scheduled maintenance interval (i.e.,

J approximately every 18 months). Performance of the applicable MI is then i

done, and trending data is entered in the accompanying PM by the i Electrical Maintenance Group (EMG) engineer. t i

1 The following items are recorded and used in SQN's trending program.

i 1. STA installation date (replace if insta11ntion time 1 60 months) k

2. UVTA installation date (replace if installation time 1 60 months) [

3. UVTA dropout voltage (before lubrication and after lubrication)  !

j 4 Trip bar trip force l

i 5. UVTA coil resistance c I 6. UVTA insulation resistance  ;

I 7. Breaker actuation response time (for undervoltage trip)*  !

i 8. Breaker insulation resistance (phase-to'-phase and phase-to-frame) e

• Note: This is not recorded for the BTBs, only RTBs. This function is [

l performed in accordance with Surveillance Instruction 227.1, i l "Post Maintenance Response Time Test of Reactor Trip Breakers RTA l and RTB"I but data is also recorded in MI-10.9.1 and the  !

i associated RTB PM. l t

i If a trend develops that will result in the continuation of data outside f

, the acceptable trending parameters, immediate action must be taken to l resolve the problem and obtain acceptable results to ensure proper

' Dreaker operation. These results are reviewed by the responsible D!C 7 a engineer who in turn revises the PM to permanent! cord the latest i j trending data and verifles no unacceptable trends

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_4 In conclusion, the four items requested by NRC to be addressed are incorporated into the SQN RTB maintenance program. The responsible EMG engineer reviews the trend data af ter the performance of either the RTB or BTB (MI-10.9.1 and MI-10.9.2 respectively). The normal sched.ule for the maintenance of the RTBs (including the BTBs) is at least every 1,8 months, as recommended by the W MPM dated November 20, 1986. The trend data for these breakers is maintained in the appropriate PM for each RTB and BTB. Any trends that are found to be outside the trend parameters are resolved by the EMG and the responsible engineer. This ensures that the SQN RTB maintenance program is maintained to be in compliance with both items 4.2.1 and 4.2.2 of GL 83-28 and the W MPM requirements.

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