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Provides Justification Re Events Leading to Declaration of Alert on 900403 Due to Loss of Emergency Svc Water When Manway Flange Gasket Leak Developed at Pump a Discharge Strainer,In Response to Ocre 900406 Petition
	ML20043A477
Person / Time
Site:	Perry
Issue date:	05/16/1990
From:	Lyster M; CENTERIOR ENERGY
To:	; NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
	PY-CEI-NRR-1174, NUDOCS 9005220115
	Download: ML20043A477 (5)
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620000k Tree Boulevard Mod Address

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'i " " 216 44F3100 Cleveland.04 441014661!

, !May:16i 1990, PY-CEI/NRR-ll74 L U.S. Nuclear / Regulatory Commission:

Document Control

Desk- 4 Washington, D. C.: .

20555 Perry Nuclear Power H ant Deecket No. 50-440 >

-Loss of!ESW and-April 3,: 1990 Alert Declaration Gentlement ThePerryNuclearPowerPlant(PNPP)isproviding$by'thisletterasummaryof the: events leading'to the' declaration.of an-Alertjat.PNPP on. April 3,11990 and results iof subsequent analysis performed. This information ia intended to 3

. assist, in. the. Staf f's preparation of a response. to the Petition- for:Immediate .l Enforcement Action filed by the Ohio-Citizens For Responsible. Energy. Inc. 1 (OCRE) regarding the April 3, 1990 event. At. issue in-this~ Petition is.

Technical Specification 3.7.1.1 which indirectlyfrequires that an inoperable Emergency. Service Water-(ESW) System (P45) Division be restored within.72 !

hours-or the plant shallibe placed in at least. hot-~ shutdown'within the next;12 -

ji hours. For reasons described in this letter, it will:be shown that"the ESWL '

inoperability declaration was overly.conservativeJand that at all. times during this event'the ESW was actually operable and plantishutdawn would:never have-been warranted. >

The information provided is under the heading:of:(1).ESW Design, (2) Operating- j Experience, (3) April 3, 1990 Alert Description, (4)-Analysis.and (5) Summary Position.

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ESW Design

'Because of the design features of the ESW intake / discharge structures, it;is j highly unlikely that any significant amount of. debris will enter the ESW pumphouse and clog the se eens. _ The intake:systemJis designed for an approach f velocity of 0.5 fpn which diminishes ~the uptake of debris.- The ESW system

' water inlet is located more than one quarter mile offshore and submerged more -

q than 15 feet below the surface of-the lake'. In. order for debris to enter the ESW pumphouse, the debris would have to be submerged-to the elevation of:the d intake heads, travel approximately 100 feet vertically downward, travel ;

l approximately 3000 feet almost horizontally and then rise vertically approximately 100 feet to the ESW pumphouse forebay.

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'The; design of the ESV'rystem forebay incorporates'two parellel-traveling

, screens for removing debris that may have entered through.the intake

. structure. The nominal design ~ approach velocity-for,the' traveling screens ist -

also .5. fps to minimize' uptake of debris. Each screen design has the filtering capacity to supply; vater.for'both Units-(1-and'2) during dual Unit-accident. conditions. requiring'all ESV and-fire pumps operating simultaneously. :

The traveling seteens act as~ rough filters for.the ESV system;to-ensure that debris, including Ilsh, is filtered outz of;the lake water and prevented from ,

entering the suction,of:the ESV pumps. The two parallel redundant trains-of- j traveling' screens can withstand a single failure and still perform.their. _

j f unct.ionr _ Although the screens are designated "A" and "B" they are installed ;

in paralle1~as. described above and serve.a common suction bay from which all ESV pumps for.both units 1 and 2 drav suction supply vater. . Each' individual traveling screen has the. capacity to supply water with all. Unit.1-and Unit 2) .

ESV pumps.and fire protection pumps operating and still' maintain a relatively: 1

.lov approach velocity minimizing debris accumulation nnd clogging potential..

The emergency design approach velocity of lft./see to.the' traveling screens; vas calculated assuming lov lake level (resulting in only 20 feet of activei 4 traveling screen height), two unitsioperating and all ESV and fire pumps _ 1

. operating, andLone equivalent traveling screen.of flov area.-

-The purpose of the ESV. Screen Wash Syctem (P49) is to provide clean waterLto i the_sprayfnozzles located in each ESV traveling screen and to provide water to a flush through the. screen trough.c The P49. system is divided-into two trains, f

each serving a corresponding ESVotraveling screen.' The1ESV Screen Wash System is automatically activated by either a LOCA signal or a high-' differential i

water level across the traveling screens. Differential water level is-indicative of blockage.~The ESV System control logic design incorporates the LOCA-signal auto start of both the-traveling screens and screen vash as purely- '

a precautionary measure. Should it be necessary,~ manual action can be taken' to clean the traveling screens for either screen:vash failures;or loss of automatic rotation. ]

Operating Experience i

As documented in PNPP's Appendix R' review, USAR Vol. 22, section 9.A.7 pages G8-6 and G8-7, the ESV pumps were operated without the availability of the traveling screens (i.e. no screen rotation or vash) during:a'tvo month period

-in 1984 (October / November) vith no noticeable deltaLP increase across the _1 screens.

a Routine inspections of the ESV screen wash,-screens and screen trash basket have yielded negligible accumulated debris. In addition to routine. -

inspections, CEI conducted:a program in 1988 to monitor fish impingement.in !

the Service Water (SV) and ESV pumphouses to determine the impact of SV and ESV system operation upon the. fish populations in the nearby waters of Lake

' Erie. All impinged materials were washed daily from the trcveling screens into a trash basket designed to allow vater to escape:while retaining fish and deoris. Fish vere collected weekly, organized by species, and various data i tabulated. This program was continued from December 30, 1987 to December 27, 1988 for the service water system but for the ESV was discontinued within veeks after attempts to obtain meaningfel data from the ESV system proved sp 4

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f'u t ile. No fish and only~a negligible amount of debris were obtained from the ESV traveling screens and only accumulated silt which settles out of the vash water vas observed in the catch basket. Additional-recent. experience'in-operating ESV "B" loop with ene P49 screen vash pump available for over.four months: vith no . noticeable reduction in1 flow capacity and'no observed screen i vash' activation, was consistent with earlier experience.. '

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, - '!t April-3, 1990 Alert Description.

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.On April 3,'1990 Division'l of;the ESV system vas rendered inoperable'at 12:35 a.m. When a manway flange gasket. leak developed at..the ESV (P45);"A" pump discharge strainer. Because of.'this leak, the "A" loop of.the'ESV system was-declared inoperable which rendered the Division 1 diesel generator inoperable. l As a further result of this leak, the ESV Screen Wash System (P49): pump "A"'. !

vas also rendered inoperable'when spray water from the leak entered a motor--

control-panel containing the starter that supplies.pover to the ESV Screen Vash. System pump.. strainer "A" motor, causing a short circuit. AtL2:32 a.m.,

1 following a review of plant' status as required by Technical Specification (TS):

3.8.1.1.e, a conservative decision vas made to also declare-Division 2 of the '- ;

ESV system inoperable because.of the unavailability of both ESV Screen Wash y

System pumps. .At the time of the above' event.the:ESV Screen Wash' System pump ~ !

"B" vas-out of service for maintenance. The unavailability of'both the ESV screen wash pumps "A and ."B"- rendered: the automatic; backwash ' capability for -

the traveling screens inoperable. As a consequence of declaring ESV loop "A"

and "B" -inoperable, TS 3.0.3 was ~ entered and the: Alert declared. PNPP ' q declared the Alert in accordance with:the PNPP Emergency Planion April.'3, 1990, at 2:37 a.m.

The decision to declare Division'2 of the ESV system inoperable duetto loss of automatic screen vash capability in the ESV Screen Wash System was considered! .

L -a very conservative decision because: (1)'the. screens 1 vere clean at the time- ,

'of the incident, (2) the ESV intake / discharge' structures are designed.so~as-to.

h L minimize the potential for intake of_ debris and-thereby to minimize potential.

i for screen clogging, (3) the operating history of the ESV system discloses no l' prior incidences of screen clogging, (4) ESV loop "B" v'as in' fact operating;at i L the time of the event and fully. capable of. performing:its intended function' i

j. notwithstanding the inoperability of the screen wash system,.'and (5) manual screen backvashing capabilities vere available. The consequences of this l 1d ecision, culminating in the declaration of an Alert, have caused PNPP to

, review and clarify the role of'P49 as an ESV support. system.: Based on this

! review, we have concluded that operation.of-the ESV system does not require ?

l operation of the ESV Screen Wash for the traveling screens, j

~ To clarify the need.for P49 as-a support system, we have. reviewed the design l basis for this system, re-examined discussions of the system in PNPP's Updated .

Safety Analysis Report (USAR) and reviewed the operating history of the.

P45/P49 systems. In addition, calculations vere performed to verify that the ESV systems will function even if the P49 screen vash system is-not available.

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/ USNRC. May 16, 1990 f PY-CEI/NRR-ll?4 1. l 4

i Analysis 'l ;

Following the. April 3, 1990 Alert, a design calculation vas< performed to-

' verify that the: ESV system vill; function if the_ P49 screen vash system were -i not'available.- The calculated flow rates were performed to verify the premise

-f that the lack of debris encountered in PNPP's ESV screens is attributable to i an extremely.lov flow velocity across the screens, . Specifically, the' design i calculation was performed for the purpose of verifying that the ESV system, could be run;for at4least: 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months without operator action.'- (Seventy-two hours is a previously evaluated time period related to Appendix Rideviations). >

This was accomplished by correlation of actual operating flow-rates, system _!

-debris collection experience and design conditions. : The analyzed flow rates. 9

' vere calculated based on two traveling screens, and one. unit operating under- ,

accident conditions requiring two'ESV pumps and all, fire pumps,-equal-to, t 17,480 GPH total' flow.- The results of this' analysis indicate nominal flow velocity of or.ly 0.162 fps across the ESV screens, . compared to 'the .5 ' fps :

design flow documented in the Environmental Report. In addition, an earlier design calculation vas reviewed which determined a flov velocity of .27 fps for the very conservative case with all Unit 1 ESV pumps and fire; pumps-operating at-the design basis lov.1'ake level. .These.results were reviewed by-the Plant Operations Review Committee and it was concluded,-based on these lov, l flov~ rates and experience-to_date.-that it was_ extremely-unlikely that any significant' amount of debris would collect on the' screens ~before manual '-

actions could be taken.

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The USAR has been revised to reflect the conclusio'ns discussed above and to provide clarification.concerning the-effects of inoperability of the-P49 system. The USAR change can be summarized by the following 6 points:.(1) the '

design of the ESV system inlet and traveling screens is such that operability i of the screen wash system (P49) is not required'for the operation of the ESV J system _(P45) , (2) one ESV traveling screen is sufficient to provide the flov a requirements for all Unit.1 and 2 ESV pumps and fire protection pumps, (3) l operation of only one screen vash subsystem vill: ensure that .one traveling screen'is.kept clean at all times, (4) if both screen vash subsystems'become inoperable there.is a high degree of confidence that each traveling sereen vould remain clean for a period of at least 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months from<the time its respective-screen' wash system became inoperable, (5)'if.'both screen' wash subsystems become inoperable, there exists sufficient time to_ manually rotate screens.and clean them using an alternate water. supply as necessary, (6) plant .t procedures require that the screens be inspected within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months of a complete loss of the P49 backwash _ system and every'24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months thereafter with manual cleaning being performed as necessary. Applicable PNPP operating. procedures have been revised to include the inspection requirements out' Lined above and to include a procedure for manual'eleaning of ESV traveling screens whenever.

automatic screen wash capability to both ESV traveling screens _is unavailable.

Summary Position With regard to the petition filed on April 6, 1990 with the Director, Office of Nuclear Reactor Regulation, by the Ohio Citizens for Responsible Energy (OCRE), we do not agree with the OCRE contention-that TS 3.7.1.1 required .

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. i Division 2 of the ESV system to be declared inoperable when "the backwash pump for Division'2 ESV system became inoperable" (see OCRE Petition, page 3).

This-contention appears to be based on'the assumption that train "B" of the

. P49' system alone services-loop "B" (Division =2)'of the ESV system.- As <

' discussed above, this'is not the case. 'Each P49: screen vash train services a

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corresponding ESW. traveling screen. The ESV system contains'two paralleli traveling screens dividing the forebay _from a common suction bay-_from which r all Unit.1 and_ Unit 2 (not currently _ operational) ESV. pumps drav their suction

' supply . water. Tha;P45 and P49. systems:are designed such that one traveling: . _.

screen is sufficient to provide the flow requirements for all Unit 1 and Unit! !

2 ESV'and fire pumps. As long as one P49 screen vash system train is. *

. operablei. the ESV system ~is fully. capable of performing its specified r functions, even.under debris clogging conditions ~. Removal'of one P49 screen vash subsystem from service has'no adverse effect'on the ability'of-__the ESV system to perform its specified functions. Removal'of both screen vash' ,

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subsystems also has no' adverse effect in that: manual cleaning of'the traveling screens can;be performed if debris begins to' accumulate.

Prior to removal of the "B" screen backwash pump from service.in November

- 1989, Division 2 of the ESV system vas' inservice'and fully capable of.

.performing its specif ei d function.' Removal ec.the!OP49 screen backwash pump _

-did not cause Division 2 ofuthe ESW1 system to!be inoperable and:in; fact after the backwash pump was-removed from service, Division 2'of the ESV system.. ,

remained-in service. In addition, at'the time that-the ESV screen backwash pump "B" was removed from service, : screen backvash pump "A", was fully capable y of performing :its function 'in support of both, divisions.'of _ the' ESV system.-

Therefore, in accordance with PNPP Technical-Specifications the OPERABILITY!of ..1 ESV Division P. vas unaffected by the removal of the'"B" backvash pump'from c service. ,

calculations, together with PNPP's ESV.(P45/P49) operating history from'1984 -

to' April 1990, confirm that it is reasonableto assume the ESV' system vill not ;

be affected by an out of service P49 screen vash : system for:at least 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

Furthermore, there is no reason to believe that the ESV system could not. ,

continue to operate indefinitely without the P49 system. 'Although the ability. ,

to operate the ESV system with the'P49 system inoperable 1for at least 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months ~ , ,

is already addressed.as.an Appendix R deviation in Chapter 9 of the USAR, 4

further clarification has been provided by revising the ESV section of the '

!- USAR.

If you.have any questions, please feel free to call, f

Very tr ours, jj Michael D. Lyster .

Vice President - Nuclear ?

Perry Nuclear _ Power Plant c

HDL:nje :

cc: T. Colburn P. Hiland

US NRC Region III j

ML20043A477

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