ML19275B647

RO-2-79-52/1P:on 791127,seismic Capabilities of Concrete Block Walls on Elevation 135 Ft Reanalyzed as Less than Required Safety Factor.Caused by Engineering Design Deficiency.Mod of Wall Support Will Raise Safety Factor

ML19275B647
Person / Time
Site:	Peach Bottom
Issue date:	12/06/1979
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:
References
NUDOCS 7912270393
Download: ML19275B647 (2)

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PHii.ADEI1'lil A TI.EITI<lt O NPANY JD D

Panch n,tter- %e l e P + e r '; tori m Of$3q y1-C iu December 6, 19'9

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',0 Mr. ~Boyce !!.' Grier

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,., Office of, Inspection and' Enforcement

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.e United States Nuclear Regulatory Cocunission

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631 Park Avenue 4

King of Prussia, PA 19106 SUII.TECT :

REPORTAllili OLQRRENG - NOMPT NOTI riC \\ TION Confirming the noti fien*. t on of Ifr. Greernman, Region 1 United States Nucient Regulatory Comission on November 3n, 19 '9.

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Reference:

Docket Nos. 50-277/273

. Peach Bottoci Units 2 4 3'

"; Technical Specification

Reference:

6. 9. 2. a(9)

Report ' No. 2-79.-52/IP (Update).

Occurrence Date:

November 27, 1979 Update:

December 5,1979

~~' Identification of Occurrence:

Pursuant to NRC In foma t.s on Not i c e No. 79-28, Engineering analyzed four _,

concrete block walls located on elevation 135' of the Units 2 and 3 j

Reactor Buildings.

These walls are the north and south walls of tho' North and South Isolation V nive Roems, respectively, irt both Reactor ButIdings.

Bechtel, Corporation has reanalyzed the.=elsmic capabilities of the subject walls and has indiented that ur.ing present day calculational methods the safety factors of the concrete expansion holts associated with the. channels which support the subject walls are greater than 2, but less

. than the desired safety factor of 4.

5 Apparent Cause of Occurrence:

l Engineering design deficiency.

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em3 Analysis af Occurrence:

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Corrective Action:

Modification of the support of the concreto and concrete block wn11 wi11 raise the bolt safety factors to a minimten of 4.

Corrective action for the two IJnit 3 concreta block walls is. scheduled to be cor:pleted by December 15. 1979, while codificat A <ms to the corresponding

.-.. Un i t 2 walls are schedirled to be coepleted by.!anuery 1, 1980.

Pravious foiluren:

None similar.

Very trtily yourn,

Mw-W. T. Illlrich Stat ion Superint endent hTd:jlw een.

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