ML19339A320

Interim Deficiency Rept Re Beam to Column Connection Design in Reactor Containment Bldg.On 781025,certain Loads,Load Combinations,Stresses & Design Inputs Improperly Applied in Structural Steel Framing Design.Reanalysis Is Continued

ML19339A320
Person / Time
Site:	South Texas
Issue date:	10/24/1980
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-566, NUDOCS 8011030583
Download: ML19339A320 (6)

Text

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The Light

.nxasnooi COntpany a--ugsgu- mux noo n- 0 13)228-9211 October 24, 1980 ST-HL-AE-566 SFN: V-0530 Mr. Karl Seyfrit Director, Region IV Nuclear ReJulatory Comission 611 Ryar. Plaza Drive, Suite 1000 Arlington, Texas 76012

Dear Mr. Seyfrit:

South Texas Project Units i&2 Docket Nos. STN 50-498, STN 50-499 Interim Report Concerning Beam to Column Connection Design in the Reactor Conta4 ment Building On September 24, 1980, pursuant to 10CFR50.55(e), Houston Lighting &

Power Company notified your office of a reportable item concerning Reactor Containment Building (RCB) Structural Steel Beam to Column Connection Design.

At that time, HL&P requested to reopen a previously closed deficiency con-cerning thi same subject. This deficiency involves the failure to paperly consider application of certain postulated loads on the interior structural steel beam design.

Please find attached our first interim report concerning this deficiency.

The next interim report will be submitted to your office by February 17,1981.

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

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

Very tr ly yours, f W Execu ive N President MEP/pjb \S ,

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October 24, 1980 Houston Lighting & Power Company ST-HL-AE-566 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)

J. 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 Comnission Washington, D. C. 20555 h . - - . . . - -

1 October 24, 1980 Houston Lighting & Power Company ST-HL-AE-566 i 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. Raage Central Power 6 Light Company P. O. Box 2121 Corpus Christi, Texas 78403 s

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 Antcnio, Texas 78296 A. vonRosenberg City Public Service Board P. O. Box 1771 San Antonio, Texas 78296 4 P* .

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October 24, 1980 Houston Lighting & Power Company ST-HL-AE-566 SFN: V-0530 Charles Bechoefer, Esquire Page 4 Chairman, Atomic Safety 4 Licensing Board U. S. Nuclear Regulatory Comission 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 San Antonio, Texas 78205 Citizens for Equitable Utilities c/o Ms. Peggy Buchorn Route 1, Box 432 Brazoria, Texas 77422 Richard W. Lowerre, Esquire Assistant Attorney General for the State of Texas P. O. Box 12548 Capitol Station Austin, Texas 78711 Berna.J M. Bordenick Hearing Attorney Office of the Executive Legal Director U. S. Nuclear Regulatory Commission Washington, D. C. 20555

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Interim Report Concerning i Beam to Column Connection Design in the Reactor Containment Building October 24, 1980 On October 25, 1978, pursuantto10CFR50.55(e),HoustonLightingand Power Company notified your office of a potentially reportable deficien-cy involving numerous instances where certain loads, load combinations, allowable stresses and design inputs were improperly applied in the design of the Reactor Containment Building Internal (RCBI) structural steel framing.

In our report on this deficiency (ST-HL-AE-314, dated December 27,1978),

Brown & Root comitted to the reverification of all RCBI Structural Steel calculations and correction of any designs found to be deficient.

During this reverification process, it was found that previous calcula-tions were adequate for loading in the vertical direction only. Hori-zontal components of forces such as Thermal Loads, Seismic Loads, and Reactor Containment Fan Coolers Duct Design Pressure Load were not taken into consideration or were assumed to be negligible.

Consequently, the design of structural steel connections was executed in acc6rdance with AISC Manual of Steel Construction Part 4, Table One, which h satisfactory only for leads in the vertical direction. Loads in the horizontal directions were not taken into account in the design of beam connections or in the design of embedded steel plates used for connecting beams to concrete walls. Likewise, effects of these hori-zontal loads on the design of beams, columns and concrete walls were not considered.

A special task force was created to perform investigations, reanalysis, design, design checking, and detailing, associated with the reverifi-cation and correction of the RCBI structural steel.

Since the original calculations were prepared manually and did not include all design parameters, it was decided that these calculations could not be used in this reverification effort, and a complete re-analysis and design is needed. This reanalysis is being executed by using ICES (STRUDL) computer program for all steel framing inside the RCB. All vertical, axial and transverse loads are being included; stability of steel framing will be ensured. Adequate transfer of loads from the point of application down to the top of containment mat is being provided.

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Themal Load is self limi+.ing load, where the magnitude of force is reduced in direct proportion with the freedom of a member to expand.

Also, this load increases in direct relation with any increase in the cross sectional area cf the structural member.

Based on the above characteristics, it was detemined that replacing some existing connections by expansion joints is the best solution to l i

qualify the steel framing for thermal loads. Location of these ex- '

pansion joints is selected in a way to provide maximum themal relief without impairing che structural functionality under other loads. j Since steel columns were designed to carry only vertical and local f l

eccentric loads, the horizont.al seismic loads are transferred to concrete walls and concrete floors. Some connections at the interface between steel beams and concrete walls will be replaced by heavier connections to allow for this transfer and to secure the steel framing l 1

to the concrete walls. Also, some interior connections in the line of load transfer will be changed to heavier ones.  ;

RCFC Pressure load is applicable to the floors at elevations (-) 2'-0" f and 19'-0" only. It is a result of design accident pressure within the )

RCB and acts from outside of the RCFC duct toward the inside of the

. . ,. duct. In order to transfer this load from the point of application to the concrete wall, some connections will be revised, me beams will have additional stiffeners or cover plates. Also additio.31 bracings will be added in the high pressure zones.

Due to the complexity in the behavior of the framing systems und6r various load combinations including themal, seismic, and pipe rup-ture loads, it is difficult to predict the consequences of not cor-recting the subject deficiency. Thermal loads are self-limiting -

type loads, and the themal stresses start decreasing at the same time the structure starts defoming. The Tensile Strength of A36 steel varies over a wide range from a minimum of 58 ksi to a maximum of 80 ksi. The peaks for each individual load considered in the design may never coincide at the same time, and each load will have its own time history which is different from the time history of other loads.

For these reasons, it is extremely unlikely that any type of faGure of steel or excessive defomation constituting a safety hazard could occur.

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