ML20216C934

Potential Significant Deficiency Rept 86-14 Re Outside Containment Flood Analysis.Initially Reported on 860917. Outside Flood Analysis Calculation Revised to Elevate Lines Previously Exempted from Analysis

ML20216C934
Person / Time
Site:	Beaver Valley
Issue date:	05/28/1987
From:	Sieber J DUQUESNE LIGHT CO.
To:	Russell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
2NRC-7-148, 86-14, NUDOCS 8706300407
Download: ML20216C934 (5)

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2NRC-7-148 -

3 Beaver Valley No. 2 Unit Project organiiation Telecopy 1

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May 28,'1987, 8o

- shippingport, PA '15o77

. United' States: Nuclear Regulatory Commission Region I...

631 Park. Avenue 1 l

.Kingiof. Prussia, PA 19406 g

2

.' ATTENTION: Mr. : William T. Russell 1

' Administrator SUBJECTi-

. Beaver Valley Power-Station - Unit No.i 2 Docket'No.^50-412 i

Outside Cont _ainment Flood Analysis Potential.Significant Deficiency Report-86-14, Update EGentlemen:

This update. with -- regard to.Potentially Reportable Significant Deficiency Report - SDR '86-14, "Outside Containment Flood Analysis," is being ' transmitted.'

due ' to a change in. the Lcorrective action.. As described in the Attachment,

. further analysis -has determined.that the floor barriers to protect the Class IE 480V Unit Substations.are not required.

^

DUQUESNE LIGHT COMPANY By

// J.. D. Sieber

.(pice President Nuclear

'LMR/ijr NRC/LMR/SDR/0614

' Attachment AR/NAR.

cc: ;Mr.-P. Tam, Project Manager (w/a)

Mr..J. M. Taylor, Director.(3) (w/a) (w/a)

Mr. J. Beall, Sr. Resident Inspector s

- Mr. L. Prividy, NRC Resident Inspector (w/a)

INP0 Records Center (w/a)

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j 8706300407 B70528

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.' ATTACHMENT 11.

Summary The~ Engineering ' Assurance Hazards Program Audit.'has: identified

'an.

unjustified assumption. in the design basis of-the outside containment-

- flooding.. analysis.

. Correction of-this assumption has increased-1

' auxiliary and service building calculated flood heights. _ Flooding to these heights; could submerge _ certain. essential. Class 1E components and jeopardize preservation of safe shutdown 'capah,ility.-

-2.

-Immediate. Action Taken l

High energy' lines. located.in Category I areas outside containment,were j

evaluated to ensure proper consideration. as: potential flood sources.

.This. evaluation concluded 'that double ended rupture of the Main Feed-water Lines in. the Service. Building ~ could impact safe operation of BVPS-2 if no corrective action were 'taken.

i

.0n' September 17,. 1986,-Mr..R.

J.

Wa11auer ~(DLC) notified Mr.

D.

Limroth- (Region 51, USNRC) that 'DLC considered this issue to be poten-tially: reportable under the requirements of 10CFR50.55(e).

A Final

'l H

Report, 2NRC-6-110,:was. issued on October 20, 1986.-

l 3.

Description of Deficiency ~

'!-l Project Technical Procedure 2BVM-114

" Essential Systems, Components, a

and Instrumentation Required for Safety Functions," establishes the design basis for evaluating the flooding effects of postulated piping f ailures required by Standard Review Plan Section 3.6-1.

A statement in the flooding design. basis assumed that 100 percent of process fluid J

above 212*F would flash to steam if it flowed -out of a. double ended pipe rupture.

This assumption was not conservative since an analysis of a main ifeedwater line rupture. demonstrates that approximate 1y' 25 l

percent of the process fluid would flash to steam.

.4.

Analysis of Safety Implications Reanalysis of a main feedwater line rupture in the service building conservatively assumes that the total volume of the condenser hotwell is deposited on the 780'-6" floor.

Although this produces. a 14 inch flood height, no safety-related equipment is affected -at this eleva--

. tion.

Due to transmission through open doors, collapsed ' vent ducts,.

and crumbled walls, this event produces the most limiting flood height 1

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L(continued),

lin all elevations of. the auxiliary and. service buildings (See. Attached 4

FSAR Fig'ure 3.8

.46).

The Class 1E equipment which might.be submerged by this event in the auxiliary building and the-760'-6"/745'6"' elevations.of the service 1 building :is not used for plant safe. shutdown.. However,>the-flood J height' -(3.5")

inD the service building (elevation 730'6") might'

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affect floor mounted vital switchgear that.is used 'for safe-shutdown '

capability.

^5.

Corrective' Action To Resolve The' Deficiency.

Original.ly, flobd barriers were determined to be' required to protect Cla'ss

.IE - 480V'.switchgear 480VUS*2-8 and 2-9. _ Further pipe ' stress analysis and evaluation of the service building flooding 'analysisthas determined that

-operator.~ action will preclude : the requirement-forl the flood barriers' l

around. the " vent. ducts on - the 780'-6"' elevation of the service: building,.

and around the 480VUS*2-8 and 9 on the 730'-6" elevation of the service.-

building.. The analysis. indicates that ' outflow from the pipe failurg can be sustained for only ten minutes before operator ' action is required 'toi J

protect 1480VUS D operability.

The corrective actions for resolving l this deficiency.'are outlined below.

Software:-

The outside containment flooding analysis-calculation has been revisedito:

i evaluate l lines 'previously exempted. from an~alysis. Project Procedure 2BVM -

114 has been revised to correct the analysis basis.

l FSAR Section 3.6 was'. reviewed and revised 'in January,1987 to reflect the change in calculated flood-height.

FSAR Section 3.6 will be revised to incorporate the need for operator action to limit flood. height.

1 Chapter 2.53A.1, Section E.S.1, of the BVPS Emergency Operating Proce-dures (EOP) addresses - reactor trip' response without safety injection signal generation. - This procedure is_ to be revised to require that all 4

main.feedwater flow upstream of the feedwater isolation valves be termi-nated by' manually tripping the Main Feedwater (MFW). pumps i f-steam /feedwater #10w mismatch is the cause of the reactor trip.

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Hardware:

The following construction changes are being implemented to mitigate the -

flooding effects of a main feedwater line break on the service building.

1.

Door Gaskets i

Four doors will be gasketed at elevation 780'-6" and 745'-6".

Page 2 of 3 a.

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2.

Blowout Panel Installation of a blowout panel.in the service building wall has previously been identified as being required 'to mitigate the envi-ronmental (i.e., temperature / pressure) effects of a main steam line failure.

The panel will' be installed flush with the 780'-6" floor I

to mitigate both environmental and -flooding effects..

6.

Additional Reports No additional reports are anticipated.

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