RC-96-0014, Requests NRC Review & Approval of RB Tendon Force Predictions for Upcoming Fifth Period RB Tendon Surveillance.Calculations Generated for Fifth Period Surveillance Tendon Force Predictions Encl

Requests NRC Review & Approval of RB Tendon Force Predictions for Upcoming Fifth Period RB Tendon Surveillance.Calculations Generated for Fifth Period Surveillance Tendon Force Predictions Encl

ML20096E937
Person / Time
Site:	Summer
Issue date:	01/18/1996
From:	Gabe Taylor SOUTH CAROLINA ELECTRIC & GAS CO.
To:	Jacob Zimmerman NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20096E939	List: ML20096E941 ML20096E946 RC-96-0014, Requests NRC Review & Approval of RB Tendon Force Predictions for Upcoming Fifth Period RB Tendon Surveillance.Calculations Generated for Fifth Period Surveillance Tendon Force Predictions Encl
References
RC-96-0014, RC-96-14, NUDOCS 9601230104
Download: ML20096E937 (2)

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South Ctrolins Electric & Gis Camprny Gary J. Taylor P.O. Box 88 Vee President  !

- Jenkinsville, SC 29065 Nuclear Operations (803)345-4344 -l i gg -'

esmance j Janum 18,1996  ;

RC-96-0014 i i

Document ControlDesk

, U. S. Nuclear Regulatory Commission '

_ Washington, DC 20555 >

l

. Attention: Mr.JacobI.Zimmerman  ;

, Gentlemen:

Subject:

VIRGILC. SUMMER NUCLEAR STATION (VCSNS) 2 DOCKET NO. 50/395

OPERATING LICENSE NO.NPF-12 REQUEST FOR REVISION TO BASE VALUES ANDNORMALIZING i i FACTORS FORREACTOR BUILDING TENDON FORCE PREDICTIONS l i

L This letter is a follow up to the conversation between Mr. Chen Tan, NRC, and Mr. i Mike Fowlkes and Mr. Gregory Parsons, SCE&G, which took place on January 2, I 1

1996. The purpose of this letter is to request your review and approval of our Reactor Building tendon force predictions for the upcoming Fifth Pen,od Reactor Building

[ Tendon Surveillance.

The Virgil C. Summer Technical Specification Bases 3/4.6.1.6, Reactor Building Structural Integrity states the necessity of your review and a ) proval for revision of the base values and the normalizing factors contained in our 3eactor Building 4

Tendon Surveillance Procedure.

1 The following reasons are presented for the changes:  ;

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! The vertical tendons were retensioned after the last (fourth griod) surveillance.

This retensioning invalidates the previously calculated tenc on force predictions.

[L - Although the actual tendon force is expected to be peater than the previously i calculated values, it does not seem prudent to use t ie existing values, since the force in the tendons has significantly changed.

I The hoop and tho dome tendons were not retensioned; however, a review of the data i from previous surveillances shows that the tendons are acting in a predictable manner. When data from the previous surveillances is plotted on a time-log plot, the points lie on a straight line with almost perfect correlation. The squares of the correlation coefficients for the hoop and dome are 0.99879 and 0.99953, respectively.

The extrapolated values for April,1996, are as low as 91.9 percent of the previously .

estimated value. Using the previous empirically calculated estimate would therefore result in unnecessary sampimg of adjacent tendons.

- The attached two calculations were generated for the fifth period surveillance tendon force predictions. The first calculation, #DC03050-001 addresses the hoop and dome

- tendons and the second calculation, #DC03050-002 deals with the vertical ter. dons.

9601230@14960g1820092-PDR ADOCK 05000395 -Mo A Q. .

Arit O ' l- l ##I I

P PDR l

Docum:nt Central D:sk TSP 960001 RC-96-0014 Page 2 of 2 If approved, these values will be used as the base values for the upcoming surveillance.

We intend to consider the use of this traditional experience-based method for the hoop and dome tendons as long as we continue to have good data correlation, or until retensioning is required. For the vertical tendons, we intend to consider the use of this method if we have sufficient quality data to perform an accurate prediction. We also intend to review and possibly adjust our calculations for predicting the forces on the retensioned tendons, once the results of the surveillance are obtained.

Please review these documents for approval by February 8,1996. Any questions or comments during the review of these calculations should be directed to Mr. Gregory Parsons, Design Engineering, at (803) 345- 4633 or Mr. Michael J. Zaccone, Nuclear Licensing, at(803) 345-4328.

Very truly yours, SY0 h ,a c,rr Gary J. Taylor MJZ/GJT/dr Attachments (2) c: J. L. Skolds (w/o Attachments)

O. W. Dixon R.R.Mahan (w/o Attachments)

R. J. White S. D. Ebneter NRC ResidentInspector C. P. Tan, NRR/ECGB R. M. Fowlkes G. P. Parsons J. B. Knotts Jr.

M. K. Batavia K. R. Jackson DMS RTS(TSP 960001)

File (813.20 NUCLEAR EXCELLENCE - A SUMMER TRADITION!