ML19318A377

Final Deficiency Rept Re Failure of Concrete Pour A1-P3 to Obtain Initial Set in Normal Time.Apparently Caused by Abnormal Amount of Air Voids.Defective Concrete Replaced. Outline drawings,4RE0417-5R Series,Will Be Revised

ML19318A377
Person / Time
Site:	Yellow Creek
Issue date:	06/13/1980
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19318A376	List: ML19318A375 ML19318A377
References
NUDOCS 8006200378
Download: ML19318A377 (3)

Text

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ENCLOSURE YELLOW CREEK NUCLEAR PLANT UNIT 1 DEFECTIVE CONCRETE POUR IN AUXILIARY BUILDING NCR YC-052 10 CFR 50.55(e)

FINAL REPORT Description of Deficiency Concrete pour Al-P3 in the area shown on the attached sketches failed to obtain its initial set in the normal time.

Initial set was delayed three to five days.

The area of the pour affected was identified by comparing readings from the concrete test hammer.

Safety Implications Failure of the concrete to meet loading requirements for a floor slab could lead to failure of the safety-related structure. This failure of the structure could severely limit the ability to achieve a safe shutdown 1

of the plant.

Corrective Action Samples of the area of concern gevealed an abnormal amount of air voids and a unit weight of 131 lbs/ft. The defective concrete identified was removed.

Three core samples of the in-place concrete were taken to test the adequacy of concrete pour Al-P3.

The samples were taken and tested in accordance with ASTM C42. The concrete core samples indicated thst the minimum compressive strength of the remaining in-place concrete for pour Al-P3 is greater than 3000 psi, but the sample strengths are considerably below that expected for the specified concrete. Therefore, a detailed analysis was made, which indicated that concrete with a minimum compressive strength of 3000 psi will meet all loading require-ments for floor slabs represented by pour Al-P3.

The removed portions of this pour will be replaced according to Con-struction Specification G-34, using an epoxy bonding agent on the joint between the in-place and replacement concrete. The class of the replace-ment concrete will be 400.75 AFW.

The outline drawings, 4RE0417-5R series will be revised to indicate a 3000 psi design s.

ength in this area.

The outline drawings will be revised by July 1, 1980, and the removed portion of pour Al-P3 will be replaced by August 1, 1980.

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