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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3 2NRC-7-148 -

Beaver Valley No. 2 Unit Project organiiation Telecopy 1

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May 28,'1987,

, - shippingport, PA '15o77

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

631 Park. Avenue 1 g l 2 .Kingiof. Prussia, PA 19406  ;

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.' ATTENTION: Mr. : William T. Russell

' 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.

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

Inspector s

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

INP0 Records Center (w/a)

/. j 8706300407 B70528 g\

'PDR ADOCK 05000412 S PDR 1 e

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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 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.

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.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.-

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3. Description of Deficiency ~ '!

-l Project Technical Procedure 2BVM-114 " Essential Systems, Components, .!

and Instrumentation Required for Safety Functions," establishes the a 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 Page 1 of 3 y

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.4) L(continued),

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

protect 1480VUS D operability. The corrective actions for resolving l this deficiency.'are outlined below. J 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- I 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- l nated by' manually tripping the Main Feedwater (MFW) . pumps i f-steam /feedwater #10w mismatch is the cause of the reactor trip. .l j

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".

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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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