ML20236D166

Summarizes Results of Study Completed by Util to Determine Appropriate Damping Values to Be Used for OBE & SSE Evaluation of Plant HVAC Ducting Sys.Gilbert/Commonwealth, Inc Rept 2783, HVAC Damping Values Encl

ML20236D166
Person / Time
Site:	Sequoyah
Issue date:	03/15/1989
From:	Gridley R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20236D170	List: ML20236D166 ML20236D195
References
NUDOCS 8903220494
Download: ML20236D166 (3)

Text

_ _ _ - _ _ _ _ _

,p ..

TENNESSEE VALLE'Y AUTHORITY CHATTANOOGA. TENNESSEE 37401 SN 157B Lookout Place MAR 151989 U.S. Nuclear Regulatory Commission ATTH: Document Control Desk Hashington, D.C. 20555 Gentlemen:

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2 - HEATING, VENTILATING, AND AIR -

CONDITIONING (HVAC) DUCT SUPPORT CALCULATIONS - UNRESOLVED ITEM (URI) 88-12-07

References:

1. NRC letter to TVA dated June 24, 1988, " Inspection Report Nos. 50-327/88-12 and 50-328/88-12"

2. NRC letter to TVA dated August 24, 1987, "Sequoyah Design Calculation Review: Report Nos. 50-327/87-27 and 50-328/87-27"

3. NRC letter to TVA dated February 23, 1988, " Inspection Report Nos. 50-327/87-64 and 50-328/87-64"

4. TVA letter to NRC dated March 2, 1988, "Sequoyah Nuclear Plant (SQN) - Conduit and HVAC Duct Support Calculations" This letter summarizes the results of a study completed by TVA to determine the appropriate damping values to be used for operating basis earthquake (OBE) and safe shutdown earthquake (SSE) evaluation of the SQN HVAC ducting system.

These results are based on review and analysis of data collected by TVA during dynamic tests on HVAC ducting system assemblies. With NRC's review and concurrence, TVA will use these values in the resolution of URI 88-12-07 contained in reference 1.

During the week of February 15, 1988, NRC reviewed the HVAC duct support calculations for SQN. This was a follow-up to the previous NRC inspections, described in references 2 and 3, of the SQN design calculation program. TVA provided additional information as requested by NRC during the February 1988 inspection (reference 4). NRC concluded that the HVAC duct sampling program was acceptable for the restart of SQN in 1988. Results of the NRC review of HVAC duct _ calculations are described in the inspection report in reference 1.

In that reference, the NRC requested TVA to reevaluate, postrestart, the previously analyzed sample of five ducting systems using long-term criteria and to select additional samples from other duct systems for evaluation using long-term criteria. Specifically, NRC requested that, for the evaluation 0903220494 890315 PDR P

ADOCK 05000327 PNV 0f 1 An Equal Opportunity Employer L l

I U.S. Nuclear Regulatory Commission MAR 151989 of ducting systems, TVA use the same damping values as those specified in the SQN Final Safety Analysis Report (FSAR) for miscellaneous structural steel with bolted connections. The SQN FSAR specifies use of 2-percent and 5-percent damped Amplified Response Spectra (ARS) for miscellaneous steel with bolted connections. However, it does not specify damping values for the HVAC ducting system.

The HVAC duct systems, including their supports, are a complex assemblage of various structural components. The appropriate level of the system damping can only be determined by performing dynamic tests on the ducting systems.

SQN FSAR section 3.7.2 allows use of results of test data as an acceptable method of establishing design parameters. TVA had dynamically tested a series of full-size HVAC duct with companion-angle and pocket lock-type construction at the Hyle Laboratories in the 1978-79 timeframe. . Gilbert / Commonwealth, Incorporated (G/C) has analyzed this data for TVA and prepared a report (enclosed) entitled, "HVAC Damping Values," for Sequoyah Nuclear Plant units 1 and 2.

Based on the evaluations described in this report, TVA has justified damping values for long-term design of 5 percent for OBE and 6 percent for SSF for nonwelded companion-angle duct construction and 9 percent for OBE and SSE for pocket lock-type constructions.

It should be noted that the enclosed report does not apply to welded, heavy-gauge duct constructions (i.e., worst-case sample 2, reference 4). Such duct systems (pipe) shall continue to be evaluated by tabulated FSAR damping values for general welded steel structures as shown in Table 3.7.1-3 of the FSAR.

TVA requests NRC's concurrence in using 5-percent damping for OBE, 6-percent  !

damping for SSE for ompanion-angle construction, and 9-percent damping for i OBE and SSE for pocket lock-type construction of HVAC ducting systems. TVA is willing to meet with you and resolve any questions you may have during the review of the attached report.

This letter does not contain any new commitments. Please direct questions  !

concerning this issue to E. T. Knuettel at (615) 843-7215. l Very truly yours, TENN SSEE - EY AUTHORITY t

R. Gridley, M ager Nuclear Licensing and l Regulatory Affairs Enclosure cc: See page 3  ;

)

l

. U.S. Nuclear Regulatory Commission N k!h Obh l

cc: Ms. S. C. Black, Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission l One 6011te Flint, North 1 11555 Rockville Pike. I Rockville, Maryland 20852 i l

Mr. F. R. McCoy, Assistant Director l for Inspection Programs TVA Projects Division i

U.S. Nuclear Regulatory. Commission Region II 101 Marietta Street, NH, Suite 2900-

' Atlanta, Georgia 30323 Sequoyah Resident Inspector Sequoyah Nuclear Plant ,

)

2600 Igou Ferry Road l Soddy Daisy, Tennessee 37379 I

l 1

l I

I i

_ _ _ _ _ _ . _ _ _ _ . . _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .