ML20113H530

Advises of Rev to Generic Ltr 89-13 Program to Address Svc Water Sys Problems Affecting safety-related Equipment.Rev Will Implement More Appropriate Methods of Monitoring HX Performance for Lower Containment Vent Coolers

ML20113H530
Person / Time
Site:	Sequoyah
Issue date:	07/29/1992
From:	Joshua Wilson TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-89-13, NUDOCS 9208040230
Download: ML20113H530 (4)

Text

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July 29, 1992 U.S. Nuclear Regulatory Comnission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen In the Matter of ) Docket Nos. 50-327 Ter.nessee Valley Authority ) 50-328 SEQUOYAP NUCLEAR PLANT (SQN) - REVISED PROGRAM AND STATUS UPDATE REGARDING NRC CENERIC LETTER (GL) 89-13. " SERVICE WATER SYSTEM PROBLEMS AFFECTING SAFETY-RELATED EQUIPMENT" Referencest 1. NRC, letter to TVA dated July 16, 1990, " Generic Letter 89-13 on Service Water System Protilems Affecting Safety-Related Equipment (MPA L9-13) (TAC Non, 74061/74062) -- Sequoyah Nuclear Plant, Calts 1 and gn

2. NRC Generic Letter 89-13 Supplement 1, dated April 4, 1990, " Service Water System Problems Affecting Saf ety-Related Eqt.ipment (Generic letter 89-13 Stipplemen t 1)"

3. TVA letter to NRC dated January 26, 1990, "Sequoyah (SQN), Browns Ferry (BFN), and Watts Bar (WBN) Nuclear Plants - Response To Generic Letter (GL) 89-13. Service Water Syr. tem Problems Affecting Safety-Related Equipment" s 4 NRC letter to TVA dated July- 18, 1989, " Service Water System Problems Affecting Safety-Related Equipment (Generic Letter 89-13)"

-This letter provides notification to NRC regarding a revision to SQN'L GL 89-13 program as previously provided by Reference 3. This revision will implement trore appropslate and equally effective methods of [

monitoring heat exchanger performance for SQN's lower containment vent P

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9200040230'920729 PDR ADOCK 05000327' l P PDR

).S. Nuclear Regulatory Commission Pace 2 July 29, 199' coolers (LCVC). Reference 1 provided hRC's evaluation of TVA's response to GL 89-13 and concluded that SQN's then-proposed actions were acceptable.

Enclosure 1 of Reference 3 contains a description (refer to SQN response, item Cl of the tcst pregram for SQN's LCVCs. TVA has determined that test metheds originally propused for SQN'r, LCVCs do not provide meaningf td '.es t resaltu. In lieu of testing, TVA has revised SQN's -

GL 89-13 grugram t o IntJ ude periodic inspections and maintenance of the LCVCs. These rtethode, remain consistent witt the regulrenents of GL 89-l',

(Ref erence 4) and the guidance provided in Supple:mertt 1 to GL 89-13 (Reference 2).

The enclosure provides TVA's basis fot the change to SQN's GL 89-13 e

program. No new commitments are contained in this submittal.

In addit!.on, this letter provides notitication to NRC (as requested by GL !3) that SQN's implementation of GL 89-13 has been completed and that continuing prog ams have been entablished. The SQN CL 89-13 activities and continuing programs were completed for both units before start-up from the Unit 1 Cycle 5 refueling outage.

Please direct questions concerning this issue to Don V. Goedin at (615) 843-7734.

Sincerely, l 30%

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] L. Wilson Enclosure cc (Enclosure):

Mr. D. E. LaBarge, Project Manager U.S. Nuclear Regulatory Commission One bhite flint, North 11555 Rockville Pike Rockville, Maryland 20852

, NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road

{ Soddy Daisy, Tennessee 37379 Mr. B. A. W81 son, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323

ENCLOSURE

Background

By letter dated January 26, 1990 TVA submitted its response to GL 89-13 for Sequoyah (SQN) and Watts Bar Nucit.ar Plants. Enclosure 1 of the January 1990 letter contained SQN's rcaponse to Actions 1 through V of the GL. Enclosure 3 contained a sumnnry list of commitments for ooth plants. Item 2 of Enclosure 3 contained a SQN comreitment for implementing a program to verify the heat transfer capability of SQN's safety-related_ heat exchangers. This commitment, as stated, is provided below:

"SQN will implement a continuing test / inspection program (18-month i frequency) to verify the heat transfer capability of the safety-related '

heat exchangers listed in Enclosure 1. Initial testing / inspection for

" cie 2-will be completed prior to start-up f rom the Unit 2 Cycle 4 ref uelbr otne. The initial _ testing / inspection for Unit I will be completed prior ta Martcup f rom the Unit 1 Cycle 3 refueling outage."

The list of safety-related heat exchangers provided in Enclosure 1 contained a description of the test and/or inspection methods that would be implemented at SQN. TVA has further evaluated the test and/or inspection methods that were proposed for SQN's lower containment vent coolers (LCVCs) (Item C of Enclocure 1) and has determined that an equally effective alternative technique could be better utilized to satisfy GL 89-13 recommendat. ions. The following provides the basis for this change and the alternative methods that will be implemented at SQN for'the LCVCs.

Basis for Change TVA's initial program for SQN's LCVCs required tenperature measurements of' air and water to verify heat transfer capability.

To date., TVA has rerformed a total of ten tests. Four Unit 2 LCVCs were tested-during the Unit 2 Cycle 4 refueling outage, and four Unit 1 LCVCs were tested during the Unit 1 Cycle 5 refueling outage. These tests were performed during' unit start o from the outages after the normal cleaning had been performed. The LCVCs met the acceptance criteria for both series of-tests. As part of SQN's continuing program, two LCVCs were l tested during the Unit 2 Cycle 5 refueling cutage. This testing was 3 l performed upon unit shutdown-for the refueling outage before the normal l' cleaning. .Neither_ test met the acceptance criteria.-- The spread _in_the I

air-inlet temperatures (20 data pointa) varied as much as 50 degrees.

i! This temperature sprud problem was also encountered during the earlier series of accepted tests. The margins of-pass or fall have been such- .

that a one- to two-degree change in the average air-inlet' temperature li significantly changes the final test results. Consequently, TVA considers testing to be impractical for SQN's.LCVCs.

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• l Alternative Method

- TVA is revising SQN's GL 89-13 program commitment for testing SQN's LCVCs (Item C to-Enclosure 1 of TVA's January 1990 letter) to substitute the following alternative: " Periodic inspections and maintenance will be performed for biofouling siIt, and corrosion products." Inspections are currently performed on a refueling outage frequency. The inspections

-involve removing the tube plugs and visually inspecting the tube interior by metallurgical and chemistry personnel. For periodic maintenance, the  :

air side of the coolers is cleaned every refueling outage. Water-side and air-side flow rates are also verified. TVA considers these

' alternatives to be consistent with the requirements of GL 89-13 and the additional guidance provided in Supplement I to GL 89-13 (reference

.page 22).

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