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Interim Deficiency Rept Re Broken tie-down Studs in Unit 1 Polar Crane Rail.Caused by Welding W/Low Range Parameters. Encl Plan Issued for Insp & Testing of Selected Studs & Associated Plates.Failures Examined by Stud Supplier
	ML19309F392
Person / Time
Site:	South Texas
Issue date:	04/16/1980
From:	Eric Turner; HOUSTON LIGHTING & POWER CO.
To:	;
References
	ST-HL-AE-449, NUDOCS 8004290398
	Download: ML19309F392 (16)
	v • d • e

c'. 8004290 % $

Ti C The Light company

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April 16, 1980 ST-HL-AE-449 SFri: V-0530 Director, Region IV tiuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76102

Dear Sir:

South Texas Project Units 1 & 2 Docket tios. STri 50-498, STN 50-499 Interim Report on the Reportable Deficiency Concerning Polar Crane Rail Tie-Down Studs On March 20, 1980, pursuant to 10CFR50.55(e), Houston Lighting and Power Company notified your office of a reportable deficiency concerning broken tie-down studs in the Unit 1 polar crane rail.

This letter provides an interim report on the status of the investi-gation of this deficiency.

During a routine construction operation, the operator of the Unit 1 polar crane observed some unusual vibrations. During his inspection of the polar crane rail, he observed that seven of the rail tie-down studs (Figure 1) were loose. The B&R Quality Assurance Depart-ment was notified and during a random inspection of approximately fifty studs , twenty-five additional loose, broken, bent, or improper-ly positioned studs were discovered. A tionconfonnance Report was written and a " hold" was placed on the operation of the polar crane.

Figures 2 through 9 show the location of the failed studs which have been identified thus far.

The circular polar crane rail track is designed to carry the polar crane when it is under maximum design loading. The rail is attached ,

to the support girder system kith a floating clip system. These clips are held by threaded stud and nut connections. A sketch of this system is provided as Figure 1. Seismically induced motion of the ,

bridge will result in horizontal loads being transmitted first to the rail track, then to the support girders through the clip-stud system.

Under such loading, a local failure of a few studs potentially could propagate the failure to adjacent studs. In such ar. event, the track may lose its alignment, possibly resulting in dercilment of the polar l crane. g se lll l

Euston Ufr ung & Pour Company ST-HL-AE-449 April 16, 1980 Page Two The preliminary investigation performed thus far has indicated that most of the studs that failed were located at the ends of girders.

A plan was issued to cover the inspection and testing of selected studs and associated plates. The plan requires a minimum of twenty studs to be tested for each girder. A copy of this plan is provided as Table 1.

Some testing has been conducted and the results were reviewed during a meeting held at the STP Site on April 8, 1980. Pittsburgh-Des Moines Steel Co. (PGi), the containment liner contractor, stated that the failures have been examined by the stud supplier and initial indications are that the studs were probably welded using low range parameters . PDM will attempt to duplicate these conditions by welding some test studs to a plate using similar low range parameters.' In the interim, the field tests will continue and a logic plan for the comple-tion of the activities necessary to resolve this deficiency will be prepared. A report providing the status of corrective action for this deficiency will be submitted to your office on June 20, 1980.

Further questions should be directed to Mr. S. S. Rodgers, (713) 676-

~

7953.

Very truly yours, N,

2 a. . /-

E. A. Turner Vice President Power Plant Construction

& Technical Services PLW/emk Attachments e

4

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Ikx:ston Ughtmg & Pom Company ST-HL- AE-449 Page three CC: G.W. Oprea, Jr.

D.G. Barker C.L. McNeese

H.R. Dean R.L. Waldrop G.B. Painter A.J. Granger R. A. Frazar M.D. Schwarz (Baker & Botts)

R. Gordon Gooch (Baker & Botts)

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

Director, Office of Inspection & Enforcement, -

- Nuclear Regulatory Commission Washington, D.C. 20555 M.L. Borchelt Executive Vice President Central Power & Light Ccmpany P.O. Box 2121 Corpus Christi, Texas 78403 R.L. Hancock Director of Electrical Utilities City of Austin P.O. Box 1088 Aos. tin, Texas 78767 .. -

J.B. Poston Assistant General Manager of Operations

' City Public Service Board i P.O. Box 1771 San Antonio, Texas 78296 R.C. Mecke City Public Service Board P.O. Box 1771 San Antonio, Texas 78296 M.C. Nitcholas ,

- City of Austin .

. P.O. Box 1088 .

Austin, Texas 78767 R.L. Range -

Central Power & Light Company P.O. Box 2121 Corpus Christi, Texas 73403 Charles Bechoefer, Esquire Chairman, Atomic Safety & Licensing Board U.S. Nuclear Regulatory Cocaission Washington, D.C. 20555

, Fbuston bgiung & Ibwer company ST-HL-AE-449 Page four 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 i P.O. Box 12548

( Capitol Station j Austin, Texas 78711 i Henry J. McGurren, Esquire i Hearing Attorney-j Office of the Executive Legal Director U.S. Nuclear Regulatory Commission l Washington, D.C. 20555 l

, . + . -

TABLE 1 POLAR CRAtlE STUD INSPECTION AND TESTING PLAN A

The following inspection / testing will be performed by PDM on selected studs (See Figure 10 for stud locations):

1. The clip plates, filler plates and studs must be identified and documented prior to inspection.

2. Check if the clip plate is in contact with the bottom flange of rail.

3. Measure gap between the bottom flange and filler plate. Document measu rements.

4. Measure gap between rail section ends and document results.

5. Check rail curvature at ends - Use Figure 11.

6. Report uneven or excessive wear on ends of rail sections.

7. Perform a general visual inspection of nuts on studs to verify presence of hit marks or rub marks.

8. Check to see if the nuts are snug tight or loose. PDM should review the procedure and discuss with Brown & Root prior to verification.

~

9. Remove clip plate and filler plate. Perform visual inspection as follows, and document results:

a. Report change in rail curvature.

b. Visually inspect the stud shank and notch on clip plate for rub ma'rks.

c. Inspect weld and flash, and look for uniform fusion. Look for weld failure,

d. Torque test studs to 318 ft-lb. Document results.

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1" p X 2 3/4" (A.W.)

THREADED WELD STUD (TYP.)

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CRANE RAll 145-0156 (TYE.)

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ML19309F392

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Dear Sir:

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