ML19321B199

LER 80-052/01T-0:on 800709,during Review of Seismic Calculations,Exhaust Ductwork of Emergency Diesel Generators Created Overstressed Conditions at Exhaust Nozzles.Caused by Design Deficiency.Supports Will Be Added

ML19321B199
Person / Time
Site:	Davis Besse
Issue date:	07/22/1980
From:	Hartigan J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19321B197	List: ML19321B196 ML19321B199
References
LER-80-052-01T, LER-80-52-1T, NUDOCS 8007280643
Download: ML19321B199 (2)

Text

U.S. NUCLEAR REGULATERY COMMISSION Z RC FORM'J66 87 77)

LICENSEE EVENT REPORT CONTROL BLOCK: l l l l l l (PLEASE P"tlNT OR TYPE ALL REQUIRED INFORMATION) o 1 l 0 l LICENSEE Hl D lCODE B l S34l 1l@l 6 l 6 l 6LICENSE l 0 lNUMBER 6 l 0 l 6 l 6 l 025 l @ 26 l 6LICENSE l@l TYPE l

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- l 0 l 3 l684 l696 @l 0 DATE EVENT l 7 l 6 l 9 l 8 l 0 l@l0 l 7 80l 2 l 2 l 8 l9 74 75 REPORT DAT E EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l (NP-32-80-10) During the review of the seismic calculations required by Section 1 I

o a L2.C.(3)(r) of Operating License NPF-3, it was determined that the exhaust ductwork o 4 l of the emergency diesel generators created an overstressed condition at the exhaust I o 5 l nozzles. This is bein,- eported under Technical Specification 6.9.1.8.1 as a conditio5

[01s_j s l 1ess conservative than assumed in the accident analysis of the FSAR. There was no I O 7 l danger to the health and safety of the public or station personnel. l l

0 8 l 80 DE CODE S SC E COMPONENT CODE SU8 CODE S DE E I.El Elh Wh Uh l SI UI PI Ol Rl Tlh [_B_jh W h 12 13 18 19 20 7 8 9 10 11 REVISION SEQUENTIAL OCCURRENCE REPORT REPORT NO. CODE TYPE NO.

EVENT YEAR

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h M lThe cause of the occurrence is desien deficiencv. The nresent suonorts allow too miichI FCR 80-178 will be implemented during this refueline I Q l stress at the exhaust nozzles.

, , l outage to add supports and also change the expansion joints above the nozzles. I 1 3 l l

t 4 I 80 7 8 9

% POWER OTHER STATUS 015 O RY DISCOVERY DESCRIPTION ST US t s W@ l $l Ol Ol@l NA l [_Dj@l Power Systems l A TIVITY ' CO TENT AMOUNT OF ACTIVITY LOCATION OF RELEASE RELEASED OF RELEASE l

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LOSS OF OR DAMAGE TO FACILITY ,

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ISSUE hl DESC .< TION NA .oBO l s8 69 lllll1lllllll% 80 g 4

r a 9 to gg U *" John P. Hartigan 419-259-5000. Ext. 298 DVR 80.-116 NAME OF PREPAREn PHcNE:

'- TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-8P 10, o

o DATE OF EVEW : July 9, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Emergency Diesel Generators under-designed exhaust pipe support Conditions Prior to occurrence: The unit was in Mode 6, wit.h Power (MRT) = 0 and Load (Gross MWE) = 0.

Description of Occurrence: During the review of the seismic calculations required by Section 2.C.(3)(r) of operating license NPF-3 of the diesel generators by the vendor, Power Systems, it was determined that the exhaust ductwork created an everstress condition at the diesel generator exhaust nozzles during the design basis earthquake (0.15 g SSE). This design is less conservative than assumed in the tecident analysis of the Final Safety Analysis Report and is being reported under Technical Specification 6.9.1.8.1.

Designation of Apparent Cause of Occurrence: The cause of the occurrence is design crror by the architect / engineer, Bechtel Corporatf n, in that the final loads at the nozzles were not checked against the~most recent manufacturer's allowables.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. This occurrence was reviewed by our architect / engineer and

-feund to be an isolated incident and not a generic problem. The loads generated at the cxhaust nozzles were small and not checked by the stress analyst against the manufac-turer's allowable value because they were much lower than normally accepted loads for a 22 inch diameter connection. The stress analyst did not realize that this was a unique connection using flexible seals ir ' ?ad of a bolted connection.

Cerrective Action: Facility Change Request 80-178 is being prepared to add a correc-tive support to prevent the exhaust pipe from overstressing the exhaust nozzle in the event of an earthquake. These deficiencies will be corrected prior to startup from the current refueling outage.

Failure Data: . Previous reported design deficiencies concerning piping supports are fcund in Licensee Event Reports NP-32-79-08 (79-064), NP-32-79-13 (79-106), and NP-33-7 9-154 (7 9-133) . j i

LER #80-052 rt