ML20150F239

Responds to Re Discovery of New Voids in Concrete Containment Bldg.Discusses Discovery of Defect by Util & Steps Taken by NRC & Util to Correct Deficiency.No Difficulty Is Envisioned in Repairing Voids

ML20150F239
Person / Time
Site:	South Texas
Issue date:	07/26/1979
From:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:	Pickle J HOUSE OF REP.
Shared Package
ML20150F241	List: IR 05000498/1977013 IR 05000498/1978001 IR 05000498/1978003 IR 05000498/1978004 IR 05000498/1978007 IR 05000498/1978010 IR 05000498/1980017 ML20150F239 ML20209B066 ML20211E985 ML20211F004 ML20211F025 ML20211F065 ML20211F072 ML20211F096 ML20211F114 ML20211F193 ML20211F216 ML20211F234 ML20211F262 ML20211F280 ML20211F398 ML20211F419 ML20211F435 ML20211F458 ML20211F473 ML20211F489 ML20211F500 ML20211F514 ML20211F518 ML20211F541 ML20211F573 ML20211F578 ML20211F583 ML20211G038
References
FOIA-85-378 NUDOCS 7909120297
Download: ML20150F239 (2)

Text

UNITED STATES -

3N

.x "r-ilCLEAR REGULATORY COMMISEdN' "

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• *yIE,,, h - g ascion :v t- Et1 RYAN PL/.2.A drive.SulTE 1000

• b k AR LINGTON, TEX A5 76012

. July 25, '1979 -

The Honorable J. J. Pickle '.' . .. '

Representative, Tenth District, Texas 7- ,

DEPOSITIO .

~

House of Representatives -  ; EXHIB ^

Congress of the United States

~242 Cannon House Office Buildi,ng g

. Washington, D. C. 20515

. ' ~

Dear Congressman Pickle:

~

We are in receipt of your inquiry of July 9,1979, regard 5ng the discovery of new voids in the concrete containment b0ilding at the Sotrth Texas Nuclear-Project. .

On October 20, 1978, Ho'uston Lighting and Power Company (.EiLTh), in accordance with Federal Regulations, notified the Region IV Office of voids that had been identified in 'the .shell wall of the Unit No. I containmen:t building fol7cr. ting placement of the 15th lift. The voids were located in the area where the polar crane brackets are embedded in the concrete. Subsequent- to the notification and as a part of corrective action, HLLP initiated a prog: rara to datamine if other voids existed in the containment building shell warl. Additional voids were identified in the 8th lift and the Region IV Office. wtas notified on June 18, 1979.

As a result of the identification of additional voids, HL&P issued en Order to their constructor, effective June 22, 1979, to stop place: ment of safety-related concrete. Simultaneously, they initiated a program to dectermina if any addi-tional voids existed and to iden'tify factors that had cor.:tributed to void fomaticn. The Region IV Office acknowledged by letter to HL&P on June. 22, 1979, an understanding of actions that HL&P committed to -take prior to resuming placement of safety related concrete. HLLP is comitted -to evaluate the cadses and extent of the void formation problem 2nd completion of specific corrective actions which include reviess of place' ment procedures; adequacy _ of concreten..

design r5ix; optimum ratios of quality control personnel to placement personnel and supervisory personnel; preplacement. planning; and design 'of-reinforcing -; .C steel aitd embedded structures.t As~ a result of an extensive review of the itemsK identified in the letter of June 22,1979,'and because of confidence daveloped eq-on past placements in safety related structures other t.5mn contairutant , resu=p-tion of concrete placement in other safety-related structures was autherrized y effective on June 29, 1979. The . licensee's. order to sto:p placecient of concrets_

in the shell wall of the containment building remains irr effect pending' completic -

of corrective action and establishment of measures to preclude, recurrer.ce. +.o o

) l. 4 .

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~~~ 42

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The Honorable J. J. Pickle .

!)([j7 .

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Region IV is closely nenitoring HL&P's ongoing investigative gfforts to detemine if any additional voids exist under the liner of the conta-inment building and .j;-

will nyiew and evaluate P &P's cornctive actions prior to resm:ption of c=n--2-'

crate:placacent in the containnent building shell wall.

..r.' ,.- ' . , . _;6 g

~

Regarding t.5e specific questions you have raised, the voids ms'ulted.$from a.kY

, combination of placecent of concrete beneath horizontal channel pla'e stiffeners f in areas crf extmne concestion of reinforcing steel and insufficient consolida T5;

' tion of the concreta. This lack of consolidation of the concrete by the wrk'~ ~ '

forces, and failure of Quality Control personnel to identify the problem allowed

'forr.ation of voids to occur under the horizontal channel plate stiffeners. No design deficiencies have been identified. Repair of the voids is by ceans of

. a pressure gmut method which has.been reviewed by the licensee and by the NRC.

No difficulties are envisioned in repairing the voids. To preclude recurrence, the licensee is c:mnitted to corrective actions in the areas 'of bet *ar pre-planning, increased surveillance during concrete placement,. and changes in. work practice and placement techniques in areas of reinforcing steel congestion.

The repair of the voids 'in the area of the polar crane brackets has been comoletec and each bracket load tested. The polar crane has since bcen utilized to se't the reactor' vessel in place. ,

We trust that this"infonstion is fully responsive to your concerns; however, should you have further questions, please feel free to contact us.

Sincerely, .

Kar1 V. Seyfrit Director bcc.:

L. V. Gossick, EDO T. Rehm, EDO H. Denton, NRR

, ';'j:

S~

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C. C. Xanmerer, OCA ' . ' ' C.'

SECY (3) d}-

J. Coo), MPA . --- -

. ..E':1.-

V. Stel1~o, IE '

2 N

s D. Thompson, IE H. D. Thornburg, IE d-7 L. N. Underwood, IE

-(H11-1978-HD6)

G. Ertter (EDO-6889)

IE Files -

Central Files IE Reading Files EDO Reading Files K. V. Seyfrit, RIV: IE W. C. Seidle, RIV:IE ~

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