ML19322B906

RO-3-79-39/1P,update:on 791130,eight Seismic Supports Inside Containment & Supporting Control Rod Drive Piping Line Found Not to Be Seismically Qualified.Caused by Design Deficiency. Mods Will Be Completed During Outage Beginning 791207

ML19322B906
Person / Time
Site:	Peach Bottom
Issue date:	12/04/1979
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:
References
NUDOCS 7912130417
Download: ML19322B906 (2)

Text

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1771.4 Decemoer 4, 1979 Mr. Boycn 11 . Grier Office of In.,poc t ton and Enforcement j C' #3 D

Region t United States Nucient Regulatory Commission LD 'R t, 31 P,rk Avanne o D q it King of P russia , PA 1940o A w . L~ - A Q SUDJECT: DEPORTABLE O C C U R R T.N C F. - PROMPT NOTIFICATION - UPDATE Cor(ir-ing tha n o t t e' 3 catlan afHe. (;r a n ti ma n . 4..gion T. United States

'uclear angu lato ry Co=mi s s i on on December 4

. L 9 P2 Reforanca: Onckat No. 5 0 - 2 .* n Peach Doitom Unit 3 Technical S p e c t .t' L e a t i o n Re ferenc e . 6. 9. 2. A (9 )

l Report No. 3-79-39/IP (Update) l Occurrance Date: November 30, 1979 Ifpda t e : December 4, 1979  !

Identification of Occurrence: ,

Initial prompt nortfication conearnad Four selsmic =nsports associnted .

wLth tha' Unit 3 ono-inch control rod d ri ve insert and' withdraw piping l outside o f primary containrant which ara not seismic,Ity qualified.  !

Subsequent an a ly.1 t n o f hangers inside primary containment on Unit 3 nssociated with the same control rod dri ve piping linen indicates that one member o f aach of eight hangers would b* overstressed in the event of a Design Basis Harthquake. I e

Apparent Cause of Occurrence: I.

Engineering design deficiency.  ;

I Analysis of Occurrance :  ;

An engineering review of vendor design of seismic supports associated with small piping has revealed that four hangers outsLde primary containment on Unit 3 may not be capable of withstanding a seismic '

ovont. Additional analysis by the architect-engineer has indicated that one member of each of eight hangers inside primary containment escociated with the above control rod drive piping wonid be overstressed in the case of a Design Hasts Earthquake (DBE). Postulating the DBB,-

failure of these hangers and subsequent failure of the supporting piping would not prevent the control rods from scramming. Additionally, our review of the control rod drive system design related to seismic inadequacies for certain hangers indicates that no drive insert and/

cr withdrawal line would break under a seismic event. ]

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F .s i l u r e to lin p l e rn en t corractiwa tvtion for the above four hangars

( o u t.s i d a of c o n t a i n ne n t. ) within soven days of th- ocenre nee d ri t e will re qtti re Unit 3 to be placed in tha c o l ei s it ti t d own condition (refarenen letter from R. li . Cri o r.

S. 1. . D rt i t r o f f . Vlee P r e g l .la n t.. f)ivattur. N ii C . ,l e g i. o n 1, to 1979). ill e c t. r i c Production. d.itad October 21, 81o d i .t'1 c a t i on s to thn a l .u, h t seismic supports inside of contain-nont 12-7-79. will be comp l e teil <lu r i n g tit o Unit 3 outa2e vehedialed to begin P r e v i o u r; Failures:

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2 -7:1 - 3 ". / 1 P i.7c-21/1P 2 - 7 0 - 4 i f 1.' 3 - 7 o - 2 .t / t r-2-70-40/ P T-7'a-2t./i;'

2-79-50/19 3 - 7 9 - 2 '.1/ 1 P gTC D 3-79-30/1P OO 3 79-Tt/IP O Q

3-79-32/IP 9 g }( A w s A .J Very truly yours.

W. T. Ullrich Station Superintendent WTU:lla A

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