ML20236A234

Forwards Rev 1 to Lab Tests of Air Entrapment in Slightly Sloped Sensing Lines & Consequent Pressure Transmission Error. Rept Demonstrates That Sufficient Air Cannot Become Entrapped in Instrument Sensing Lines Sloped at 1/8 Inch

ML20236A234
Person / Time
Site:	Sequoyah
Issue date:	07/20/1987
From:	Gridley R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20236A238	List: ML20236A234 ML20236A254
References
NUDOCS 8707280046
Download: ML20236A234 (2)

Text

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4 TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 37401 SN 157B Lookout Place JUL 201987 U.S. Nuclear Regulatory Commission ATTN: Document Lontrol Desk Washington, D.C. 20555 Gentlemen:

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - INSTRUMENT SENSING LINE SLOPE QUESTIONS -

NORRIS REPORT NO. WR28-1-85-124.R1

References:

1. NRC letter to S. A. White dated January 15, 1987, j

" Request for Additional Information Related to Instrument Sensing Line Slope Deficiencies for Sequoyah,  ;

Units 1 and 2" l I

2. TVA letter to NRC dated April 2, 1987, " Instrument l Sensing Line Slope Questions" l

In reference No. 2, TVA agreed to send NRC a supplemental test report from TVA's Engineering Laboratory at Norris, Tennessee, that deals with the sensing line slope issue. The report is entitled " Laboratory Tests of Air Entrapment in Slightly Sloped Sensing Lines and the Consequent Pressure Transmission Error" (Report No. WR28-1-85-124.R1). Norris Laboratory has now completed and revised this report, and it is enclosed for your review.

Test Report WR28-1-85-124.R1 demonstrates that sufficient air cannot become entrapped in instrument sensing lines sloped at 1/8-inch per foot to cause an instrument error. The potential for oscillatory performance of instrument sensing lines has been addressed analytically by TVA engineering calculations that are available for NRC audit. For an instrument sensing line to exhibit oscillatory performance, there must be a specific set of parameters satisfied that relates to the quantity and location of entrapped air, physical configuration of the sensing line, and system pressure. The probability of simultaneously satisfying the above parameters is very low. The engineering analysis demonstrates that if an instrument line tends to exhibit oscillatory behavior, the behavior will be observed during normal operation and testing of plant systems.

Therefore, any oscillatory sensing lines have been observed and corrected during routine plant operation, testing, and maintenance. Also, any sensing line that has a potential for cumulative air entrapment because of the presence of insoluble gases is being physically walked down, and corrective action is being implemented before restart.

7280046 870720 p ADocg oSonogy, sy PDR An Equal Opportunity Employer

I JUL 201987 ]

U.S. Nuclear Regulatory Commission 1 If you have any questions regarding this matter, please telephone M. R. Harding at (615) 870-6422.

Very truly yours, TENNESS'E VALLEY AUTHORITY

3. Gridley, Di ctor Nuclear Safety and Licensing Enclosure cc (Enclosure):

Mr. G. G. Zech, Assistant Director for Inspection Programs Office of Special Projects U.S. Nuclear Regulatory Commission Region II 101 Marietta Street,.NW, Suite 2900 Atlanta, Georgia 30323 Mr. J. A. Zwolinski, Assistant Director for Projects Division of TVA Projects Office of Special Projects U.S. Nuclear Regulatory Commission 4350 East West Highway EWW 322 Bethesda, Maryland 20814 Sequoyah Resident Inspector Sequoyah Nuclear Plant i l 2600 Igou Ferry Road j

Soddy Daisy, Tennessee 37379 i

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