ML19339C566

Interim Deficiency Rept Re Reactor Cavity Ventilation Design,Initially Reported on 801017.Alternatives Are Being Evaluated,Including Redesign of Reactor Cavity Seal Plate. Next Rept Will Be Forwarded by 810127

ML19339C566
Person / Time
Site:	South Texas
Issue date:	11/11/1980
From:	Oprea G HOUSTON LIGHTING & POWER CO.
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, ST-HL-AE-574, NUDOCS 8011180622
Download: ML19339C566 (6)

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The Light mmPuy sees,ee <>s ,ies & ee.., s e.o. ee, ivoo sees,ee.1 x.,21ooi <2is> 22s.o2,i November 11, 1980 ST-HL-AE-574 SFN: V-0530 Mr. Karl Seyfrit '

Director, Region IV Nuclear Regulatory Comission -

611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012

Dear Mr. Seyfrit:

South Texas Project

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Units 1&2 Docket Nos. STN 50-498, STN 50-499 Interim Report Concerning Reactor Cavity Ventilation Design Please find attached our interim report regarding reactor cavity ventilation des.ign which Houston Lighting & Power Company verbally report-ed to your office on October 17, 1980 as being potentially reportable pursuant to 10CFR50.55(e). The next interim report will be submittad to your office by January 27, 1981.

If there are any questions concerning this item, please contact Mr.

Michael E. Powell at (713) 676-8592.

Very t ygyours, s / '

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Execu 1ve V resident MEP/pjb Attachment pS/ 7 8 011 1 s cQ-> sif 1

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. l Houston Lighting & Power Company November 11, 1980 ST-HL-AE-574 SFN: V-0530 Page 2 cc: J. H. Goldberg D. G. Barker Howard Pyle R. L. Waldrop H. R. Dean -

D. R. Beeth J. D. Parsons G. B. Painter L. K. English A. J. Granger R. A. Frazar H. S. Phillips (NRC)

.1. O. Read Read-Poland Inc.)

M. D. Schwarz Baker & Botts)

R. Gordon Gooch Baker & Botts)

J. R. Newman Lowenstein Newman, Reis, Axelrad & Toll)

Director, Office of Inspection & Enforcement Nuclear Regulatory Comission Washington, D. C. 20555

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Houston Lighting & Power Company November 11, 1980 ST-HL-AE-574 SFN: V-0530 Page 3 M. L. Borchelt Executive Vice President Central Power 6 Light Company P. O. Box 2121 Corpus Christi, Texas 78403 R. L. Range Central Power & Light Company P. O. Box 2121 Corpus Christi, Texas 78403 R. L. Hancock Director of Electrical Utilities City of Austin P. O. Box 1088 Austin, Texas 78767 T. H. Muehlenbeck City of Austin P. O. Box 1088 Austin, Texas 78767 J. B. Poston Assistant General Manager of Operations City Public Service Board P. O. Box 1771 San Antonio, Texas 78296 A. vonRosenberg City Public Service Board P. O. Box 1771 San Antonio, Texas 78296 i

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Houston Ughdng & Power Ckunpany November 11, 1980 ST-HL-AE-574 SFN: V-0530  ;

Charles Bechoefer, Esquire Page 4 i Chairman, Atomic Safety & Licensing Board U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Dr. James C. Lamb, III 313 Woodhaven Road Chapel Hill, North Carolina 27514 Dr. Emmeth A. Luebke Atomic Safety & Licensing Commission U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Steven A. Sinkin, Esquire 116 Villita Street t San Antonio, Texas 78205 Citizens for Equitable Utilities c/o Ms. Peggy Buchorn Route 1 Box 432 Brazoria, Texas 77422 Pat Coy Citizens Concerned About Nuclear Power 5106 Casa Oro San Antonio, Texas 77422 Ricnard W. Lowerre, Esquire Assistant Attorney General for the State of Texas P. O. Box 12548 Capitol Station Austin, Texas 78711 Bernard M. Bardenick Hearing Attorney Office of the Executive Legal Director U. S. Nuclear Regulatory Connission Washington, D. C. 20555 f

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Interim Report j Concerning Reactor Cavity Ventilation Design November 11. 1980 On October 17 ,1980, pursuant to 10CFR50.55(e), Houston Lighting &

Power Company notified your office of a potentially reportable deficiency concerning the reactor cavity ventilation design for the South Texas Project Electric Generating Station, Units 1 and 2.

The design criteria requires that ventilation be provided to the reactor cavity, primary shield wall penetrations and inspection toroid volunes suffi -

cient to maintain primary shield wall concrete temperatures within specified limits during nomal plant operation. During a recent confimatory themal analysis perfomed by Brown & Root of the reactor coolant piping supports located in primary shield wall penetrations, it was detemined that the temperature of the primary shield wall concrete in the penetration and along the face exposed to the reactor vessel would exceed the specified limits.

The structural integrity of the shield wall in these areas could be reduced because of localized concrete failure resulting from these temperatures.

Brown & Root has investigated th Cause of this design defect and deter-mined that the original ventilation calculation did not account for flow

' resistance due to the reactor vessel nozzle configuration and the reactor cavity seal plate configuration. The seal plate is required to limit asymetric loads on the reactor vessel following a break at the vessel nozzle (ref. FSAR 6.2.1.2.2.1 and 6.2.1.2.3.2). In addition, the vent area at the top of the reactor cavity is inadequate. This vent area design was based on preliminary infomation.

Assuming adequate ventilation design, the reactor can be brought to a safe shutdown condition following loss of cavity cooling without exceeding shield wall concrete temperature limits.

The current status of design and construction in the areas of concern is as follows:

Unit 1 Primary shield wall concrete has been poured to El. 29'-4".

The reactor vessel is in place and primary coolant piping welded to the reactor vessel nozzles. Primary shield wall concrete above E1. 29'-4 is on hold. The reactor cavity seal plate design has not been issued for constn .'. tion. It will not be issued until all design problems noteo - this deficiency are resolved. The reactor cavity cooling fan unit is at the site and is awaiting installation. This fan is currently placed on hold.

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Unit 2 Primary shield wall conrete has been poured to El.19'-0".

All primary shield wall concrete above E1.19'-0" is on hold.

The reactor vessel is not in place. The reactor cavity seal plate. design is in the same status as the design for Unit 1.

It will not be released for construction until all design problems noted in this deficiency are resolved. The reactor cavity cooling fan unit is at the site and is awaiting install-tion. This fan is currtently placed on hold.

In order to satisfactorily correct the design deiact, alternatives are currently being evaluated, which include redesign of the reactor cavity seal plate and potential reactor cavity venting designs.

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