ML19274E232

LER 77-006/01T-1 on 770126:review of Pipe Stress Due to Feedwater Line Vibrations Noted Six Seismically Inadequate Snubbers on Feedwater Lines.Caused by Poor Design Verification During Plant Const

ML19274E232
Person / Time
Site:	Beaver Valley
Issue date:	03/14/1979
From:	Werling J DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19274E231	List: ML19274E230 ML19274E232
References
LER-77-006-01T, LER-77-6-1T, NUDOCS 7903210005
Download: ML19274E232 (2)

Text

. . . ~ -. ... . . . . . . . . .

nac ,ogu 3g, Update Report u NwAR REcutATORv Couusss ON

, t7 m Previous Report Date 2/9/77 LICENSEE EVENT REPORT CONTROL 8 LOCK: l s

l l l l l lh e

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATIONI 8

o i 8 9 l P l UCENSEE A l BCODE lV l S l 1 Ql 0 l0 l- lUCENSE I4 16 0 l0 NuMdER l0 l0 l0 l- l0 l029 l@l4 28 l1 il l1 l1 l@lSi UCENSE TYPE 40 l

LAE W l@

CON'T E ",]

$U l L ]@l 0 l 5 l 0 l 0 l 0 l 31314 l@l 0 l 1l 2 l 6l 7l 7 74j@l0 63 7$

l 3 l 1 l 4 l 7 l 980l@

REPORT DATE I S 60 61 QOCK ET NUMSER OS EVENT CATC EVENT OESCalPTION ANO PROB ABLE CONSEQUENCES h o 2 l During a review of pipe stresses resulting from feedwater line vibrations, six l o 3 I hydraulic snubbers installed on three feedwater lines were found not adequate for l

. O 4 l seismic desien condition. An investiention of all Catecory T safety reinted I o s lsni$bbersandhangerswasperformedtoverify their conformance to requirements. l 0 6 i The investiRation TeVealed an additional tVenty-siX mechanical hancerR Which l E I required modifications. The Onsite Safety Committee reviewed the incident and I o e i found the modifications acceptable. I e, *O

, 7 g SYSTEM CAUSE CAUSE COMP. VALVE COCE CODE SUSCODE COMPONENT CODE SUSCODE SusCOCE I

7 o 9 8

I C In l@ LB_J@ LA_J@ In l A l s i c i z i a lG W@ I20z l O 9 to II 12 33 18 19

• SEQUENTIAL OCCURRENCE REPORT REVtSION LE R/Ro EVENT YEAR REPORT NO. CODE TYPE NO.

t 8,aEg V l217l227l (.--J 23 l 0 10 l 6 l 24 26 l/l 27 10 l 1 l 28 29 W

30 l---j 31 lJ_j 32 KE AC N ONP T M TH HOURS See POR 8. LE MANUP RER i

I33F l@l34Z I@ W@ W@

35 36 l0l0l0l0l 31 40 l_Y_j @

41

[N_j@

42 W@ lG l2 l5 l5 l@

43 44 47 CAUSE OESCRIPTION ANO CORRECTIVE ACTIONS h

' i o l The incident resulted from breakdown of desien verification during plant I i i i construction. nancer modifications rance from increased anchor bolt size en the I I

, 7 l addition of a new hanger at approximately the same location as an underdesigned l g l hanger to carry some of the load. In no case was any velding or other metallurgicall i 4 ,

change to the pipine required to make these modifications. I 7 s , so

. STA *

% POWE R OTHER STATUS Dis O Y OtSCoVERY DESCRIPTION s s Gl@ l 0l 0 0l@l N/A l l C l@l Review of pipe stresses l A TIVITY CO TENT RELEASED OP RELEASE AMOUNT OP ACTIVITY LOCATION OP RELEASE

. 7 1 6 8 9 h l Zl 10 l

tt N/A 44 l l 45 N/A 80 I

PERSONNEL EXPOSURES NUMBE R TYPE DESCRIPTICN i 7 l0l0l0l@lZl@l N/A l PERSONNELINJU iES NUMeER oESCRiPTiON@ '

ITITl8 9l 0 010*@l N/A l 7 11 12 50 LOSS OP OR DAuAGE TO 8ACluTV TYPE C E SCRIPTION i 9 Lz_J@l n/^ . I 4 9 to 80 79032100os 7

eunuciry oESCRiPTiON L-)

? NRC use ONLv 7

2 o 3 9 W

,$$UE o@l' to N/A l 68 69 l l l l-l l l l l l l l l :I 80 3 NAME OF PREPARER

. . e ng PHONE:

412-643-1258 2

Attachment to LER 77-6/01T -

Boavar Valley Power Station Duquesne Light Company Docket No. 50-334 During a review by the Beaver Valley Architect / Engineer of pipe stresses resulting from feedwater line vibrations, it was discovered that six hydraulic snubbers installed on three feedwater lines inside containment are not adequate for seismic design condition. As a result of the discovery, an investigation was undertaken to review all Category I safety related snubbers and hangers to verify their conformance to requirements. The investigation revealed an additional twenty-six mechanical hangers whicn required modifications ranging from increasing the size of the anchor bolts to the addition of a new hanger at approximately the same location as an underdesigned hanger to carry some of the load. In no case was any welding or other metallurgical change to the piping required to make these modifications.

The incident resulted from a breakdown in design verification procedures used during plant construction. Duquesne Light engineering personnel have reviewed the A/E calculational method for the redesigned hangers and have found them accepcable.

When the modifications were completed, the Onsite Safety Committee reviewed the incident and corrective actions and concurred that modifications were acceptable.

.