ML20151J553

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Summary of 970715 Meeting W/Bge in Rockville,Md Re Matters Related to Operability of SW Sys & SRW
ML20151J553
Person / Time
Site: Calvert Cliffs  Constellation icon.png
Issue date: 07/31/1997
From: Dromerick A
NRC (Affiliation Not Assigned)
To:
NRC (Affiliation Not Assigned)
References
NUDOCS 9708050177
Download: ML20151J553 (67)
v • d • e


Text

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _-.____.._____

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'p 1 UNITED STATES j

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! NUCLEAR REGULATORY COMMISSION

[ " "*"*"'"jh %1 1997 LICENSEE: Baltimore Gas and Electric Company.

FACILITY: Calvert Cliffs Nuclear Power Plant, Unit Nos.1 and 2

SUBJECT:

SUMMARY

OF JULY 15, 1997, MEETING REGARDING CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 - SALT WATER AND SERVICE WATER SYSTEMS On July 15, 1997, the NRC and the Baltimore Gas and Electric Company (BGE),

the licensee for the Calvert Cliffs Nuclear Power Plant held a meeting in One  !

White Flint North, Rockville, MD. The purpose of the meeting was to discuss matters related to the operability of the Salt Water (SW) system and the Service Water System (SRW). A list of the attendees is included as Enclosure 1. Enclosure 2 is a copy of viewgraphs distributed at the meeting.

The focus of the licensee's presentation during the meeting was to provide  !

information on how they intend to operate the Calvert Cliffs SW system and the 1 SRW system when Chesapeake Bay Water temperatures are in the range of 85 'F to 90 *F.

The SRW system is a closed loop cooling system that rejects heat to the SW system. .The SW system is an open loop system that uses Chesapeake Bay water.

During response to a design-basis accident, SRW provides cooling to the 1 Containment Air Coolers (CAC) and the three emergency diesel generator (EDG) heat exchangers. The service water heat exchanger design margins are relatively small and changes in design-input parameters, such as fouling ,

factors, can pose a challenge to SRW system operability. The licensee intends  ;

to replace the heat exchangers.in Unit No. I during the next refueling outage with larger plate-type heat exchangers.

In the meantime, one of the strategies BGE proposes to use when bay water temperatures reach the 85 *F to 90 *F range was to declare the SW header out of service and isolate one CAC. This isolation of one CAC eliminates heat addition to the SRW system thus providing additional margin. By taking this action, the entire emergency core cooling train and EDG remain operable. BGE states that this action is safer than securing the entire SW header. This action would allow bay temperature to reach a maximum of 90 *F before the SRW exceeds its design temperatures. The licensee indicates that many variables exist which affect bay temperature to include tides, wind, and runoff from the Shenandoah.

The staff indicated that they intend to discuss this matter with upper management and requested BGE provide a discussion in writing of how they I

9708050177 970731 D =DI 1 Pa ^= **gg7 FEC RE CEMER COPY

l intend to operate the SW and SRW systems during hot summer weather conditions. 1 Current water temperatures are in the range of 80-84 'F. At the end of the i meeting, the licensee stated that they would strongly consider isolating one CAC only.

Sincerely, '

Alexander W. Dromerick, Senior Project Manager Project Directorate I-I Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosures:

1. List of Attendees
2. Viewgraphs cc w/ enc 1s: See next page

o.

l 1

-intend to operate the SW and SRW systems during hot summer weather conditions.

Current water temperatures are in the range of 80-84 *F. At the end of the meeting, the licensee stated that they would strongly consider isolating one  !

CAC only.

Sincerely, i

/S/

Alexander W. Dromerick, Senior Project Manager l Project Directorate I-l

{

Division of Reactor Projects - I/II l l Office of Nuclear Reactor Regulation i Docket Nos. 50-317 l and 50-318

Enclosures:

1. List of Attendees
2. Viewgraphs-cc w/encls: See next page i DISTRIBUTION: See attached list 1

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l DOCUMENT NAME: G:\CCl-2\71597.MTS To receive a copy of this document, indicate in the box: "C" - Copy without

attachment / enclosure "E" - Copy with attachment / enclosure "N" - No copy Off!CE PM
PDI))' j/] lE LA:PDI-1 3 y l D:PW-1J AJ / ) l DD:DPRE n t, , I l NAME A W M icIinw SLittl # ADr(ple/(cP JZwolinski I/ M DATE 07/Af/97 07/ 3 0/97 07/,bf/97 07 m /97 07/ /97 J Official Record Copy

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HARD COPY - (Encl. 1&2) E-MAIL - (Encl. 1) m 0ocket?Fjle; S. Collins /F. Miraglia PUBLIC R. Zimmerman .

PDI-1 Reading B. Boger

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OGC A. Dromerick ACRS S. Little D. Ross (SAM)

L. Doerflein, RI G. Kelly M. Reinhart L. B. Marsh S. Stewart C. Saadu J. Tatum l R. Giardina l W. Dean, ED0 ,

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Calvert Cliffs Nuclear Power Plant Baltimore Gas & Electric Company Unit Nos. I and 2

.cc:

President Mr. Joseph H. Walter, Chief Engineer Calvert County Board of Public Service Commission of Commissioners Maryland 175 Main Street Engineering Division Prince Frederick, Md 20678 6 St. Paul Centre Baltimore, MD 21202-6806 James P. Bennett, Esquire 4

. Counsel Kristen A. Burger, Esquire Baltimore Gas and Electric Company Maryland People's Counsel  ;

P.O. Box 1475 6 St. Paul Centre Baltimore, MD 21203 Suite 2101 Baltimore, MD 21202-1631 Jay E. Silberg, Esquire j Shaw, Pittman, Potts and Trowbridge Patricia T. Birnie, Esquire l 2300 N Street, NW Co-Director  !

Washington, DC 20037 Maryland Safe Energy Coalition P.O. Box 33111 Mr. Thomas N. Prichett, Director Baltimore, MD 21218 NRM Calvert. Cliffs Nuclear Power Plant Mr. Loren F. Donatell 1650 Calvert Cliffs Parkway NRC ' Technical Training Center Lusby, MD 20657-4702 5700 Brainerd Road Chattanooga, TN 37411-4017 Resident Inspector c/o U.S. Nuclear Regulatory Mr. Charles H. Cruse Commission Vice President - Nuclear Energy P.O. Box 287 Baltimore Gas and Electric Company St. Leonard, MD 20685 Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Mr. Richard I. McLean Lusby, MD 20657-4702 Administrator - Radioecology Department of Natural Resources 580.Tay1or Avenue Tawes State Office Building, B3 Annapolis, MD 21401 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 i

LIST OF ATTENDEES BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT. UNIT NOS. 1 AND 2 JULY 15. 1997 NAME ORGANIZATION Alexander W. Dromerick NRR - DRPE Mike Norvin BGE - Operations Pat Furio BGE - Licensing Jose L. Gines BGE - System Engineering Mark "Chris" C. Nolan BGE - Design Engineering P. G. Chabot BGE - Nuclear Engineering Larry Doerflein NRC Region I, DRP Gene Kelly NRC - Region I Mark Reinhart NRC - TSB John Zwolinski NRC - DRPE L. B. Marsh NRC - DSSA - SPLB '

Scott Stewart NRC - SRI Coretta Y. Saadu NRC - DSSA - SPLB James Tatum NRC Roger J. Giardina NRC - TSB

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Enclosure 1

i SERVICE WATER SYSTEM i REVIEW l . .v . .* c 7 ~::y n e w r: n n:: u m .

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CALVERT CLIFFS NUCLEAR l

POWER PLANT I

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July 15,1997 i

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3 Enclosure 2 i- - - . - . . . . - - - - - - . . - . . . - - -

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j i INTRODUCTIONS -

__ _c -- .

P. G. Chabot Manager, Nuclear Engineering

)i j M. C. Nolan Senior Engineer, Design l Engineering

! J. L. Gines System Manager, Service i Water System, Plant

. Engineering l M. T. Navin General Supervisor, Nuclear l Plant Operations l P. S. Furio Senior Engineer, Nuclear p, .. Regulatory Matters 2 1

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i._.__..__...,_._.._._._. .____ _ _ ___..__.___. _ ____. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _

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4 i

i AGENDA

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i l e Technical Design and Impact M. C. Nolan l

of Environmental Factors l e Background and Available J. L. Gines

! Actions i

e Operational Options M. T. Navin 4

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OBJECTIVES

-n =,=,, nan e Information Exchange o Mutual Understanding Technical and Environmental Factors Actions to improve Margins Operating and Maintenance Strategies 4

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i l Technical Design and Impact of l Environmental Factors 1

M. C. Nolan - Senior Engineer t

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i OVERVIEW

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j e Heat Exchanger Testing at Calvert Cliffs l Nuclear Power Plant l

l e System Design Basis l

e Environmental Factors i e Current Operating Limits l e Design Considerations for Operation at High  :

l Bay Temperatures e Long-Term Action

! 6 L . _ . _ _ _ . _ _ _ .___ . _ _ __ _ .. _ _ _ _ _ __

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i j HEAT EXCHANGER TESTING l THERMAL PERFORMANCE TEST j .

. _ , _ = _ . . .

i o Service Water (SRW) Heat Exchanger test

program initiated in response to Generic l

Letter 89-13 (Task 2) t e Initial testing in 1990.was inconclusive l

Insufficient heat load l Inadequate installed instrumentation l Inability to separate effects of macrofouling and l microfouling i

Very high . uncertainty j j Independent assessment of heat exchanger

l. condition 7 l

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! HEAT EXCHANGER TESTING THERMAL PERFORMANCE TEST j mA mwm.w m.: ant . .- -

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o Baseline tests 1993-1996 Achieved good repeatable results j Test after bulleting to eliminate macrofouling j 16 tests with essentially identical resu,lts over four j years

" Clean" fouling resistance of 0.0007oF-ft2-hr/ Btu l - 0.0004-0.0005oF-ft2-hr/ Btu nominal

- 0.00015-0.00025oF-ft2-hr/ Btu uncertainty l Independent assessment of testing and j evaluation y

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! THERMAL PERFORMANCE TEST

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! e Limitations of full scale testing l Need to cross connect SRW system to provide i heat load Limited to summer months for sufficient heat load

! Limited to " clean" heat exchanger l

Only provides " snap-shot" of performance

Cannot separate macrofouling and microfouling i

t i

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l HEAT EXCHANGER TESTING l SIDE STREAM MONITOR o Needed time dependent performance data Validate cleaning frequency l Measure tubeside microfouling between I "bulletings" l

l e Side Stream Monitor (SSM)is a model of a j single SRW Heat Exchanger tube i e Condenser on "shell side"

! Provides constant heat load

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l Simplifies shell side calculations l .

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i HEAT EXCHANGER TESTING

! SIDE STREAM MONITOR

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e Tube side designed to replicate actual tube .

j Length, materials, diameter, fluid velocity, ,

j temperature change l e Operates with saltwater as tube side fluid l e Instrumented specifically for testing

e Monitored continuously when in operation

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i HEAT EXCHANGER TESTING l

l _ SIDE STREAM MONITOR _ - = - . .

i e Conclusions l Tubeside fouling builds up to a maximum equilibrium of 0.001oF-ft2-hr/ Btu l

Maximum " total" fouling of 0.0017oF-ft2_hr/ Btu l Ability of Clamtrol to reduce fouling is

! limited .

l -Temperature effects on growth are small l

t

-Velocity, O 2 concentration affect biofilm

-Independent assessment of SSM program 12 s.

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HEAT EXCHANGER TESTING SIDE STREAM MONITOR

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j " Summer" Fouling Factor Curve (Tsw > 550F) 1.20603

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j 8.00604- + Design Curve o

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2 0.0004 - --o-.1996 Design Foutng Curve o_.1995 Design Fouling Curve 0.0002 -

0-0 10 20 30 40 50 60 70 Time (Days After Bulleting)

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AN

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l i SYSTEM DESIGN BASIS j _ - . .

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l e Design Basis Validation ,

" Cooling Water Studies" initiated in 1987

{ Project was incorporated into Generic Letter 89-13 l

response (Tasks 2 and 4) j Reviewed / updated design basis i

Developed thermal and hydraulic models of

! cooling water systems .

l Incorporated heat exchanger test rest;ilts l

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SYSTEM DESIGN BASIS l 5'.3029ZN 2?.2M i

j e Initial Design Basis l Service Water Heat Exchanger specified for 80%

i cleanliness (0.00045oF-ft2-hr/ Btu)

Design modified during construction for single failure criteria Design temperature changed from 95oF to 105oF in 1974 but not incorporated in design basis-

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SYSTEM DESIGN BASIS

- - Mr . ti:lifiW4TmN7; l e Initial Design Basis (Continued)

, Non-conservative flow assumptions in original l design l Fail open position of diesel generator SRW control l valve not included l Minimum saltwater flow reduced from 20000 gpm

to 16830 gpm in 1987 l

i Issues were addressed through corrective action program l

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SYSTEM DESIGN BASIS

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! e Containment Cooling l

4 Containment Air Coolers (CACs)

2 Spray Rings
Containment analysis assumes 2 CACs and i

i 1 spray l Original design sized each CAC to remove 33% of l post accident heat load; each spray ring, 50% of

post accident heat load 1

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SYSTEM DESIGN BASIS

. f." i .4 . x o Worst Case Differs from Accident Analysis Containment analysis assumes lowest SRW flow; SRW Heat Exchanger worst case is maximum SRW flow l Containment analysis assumes dirty CACs; SRW j Heat Exchanger worst case is clean CACs l e Original Design Basis of SRW System was l

based on Accident Analysis Assuniptions j Common practice at time of Calvert Cliffs Nuclear

! Power Plant design 19 i-l .

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i SYSTEM DESIGN BAS!S i =

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e Current Design Basis

! Analyzes four basic cases to ensure limitina conditions are included:

- LOCA (SIAS) Maximum SRW Flow, Clean CACs i e Usually the limiting case I- - LOCA (SIAS) Minim'um SRW Flow, Dirty CACs

- LOCA (RAS) Maximum SRW Flow, Clean CACs i

e Often limiting case at high Bay temperatures

- LOCA (RAS) Minimum SRW Flow, Dirty CACs 20 i

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SYSTEM DESIGN BASIS

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i l e Current Design Basis (Continued) l Credits mechanical stops on CAC SRW inlet control valve for reduction in LOCA (SIAS) SRW i flow SRW Heat Exchanger fouling resistance t

0.0017oF-ft2_hr/ Btu l Analyze diesel generator SRW control valve l throttled and full open

Assume minimum required saltwater flow l 21 4

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ENVIRONMENTAL FACTORS t

HISTORICAL TEMPERATURES l ,

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LO4AAXIMUM SW TEMPERATURES .'

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CURRENT OPERATING LIMITS L - w.- u -^;.:- m _, m ,

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e Operating limits based on the current design j basis have been incorporated into 01-29, Salt l Water System Operating Instruction Variable saltwater Delta P limits to ensure design heat duty is available Maximum saltwater Delta P limit to limit tube f

erosion-corrosion j -

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CURRENT OPERATING LIMITS 1
TYPICAL 01-29 LIMITS

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CURRENT OPERATING LIMITS O1-29 LIMITS

.- ,n n-_n, o Basis of Saltwater Delta P Limits Assumes heat exchanger is fouled at the design limit, i.e., 0.0017oF-ft2_hr/ Btu

! Determine tube blockage l'macrofouling) that will not prevent removal of design heat load Convert tube blockage to a saltwater Delta P limit i

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CURRENT OPERATING LIMITS i OI-29 LIMITS

_ . _m____ . .

! e Assumes microfouling at the maximum test

value plus uncertainty 4

j e Limits in procedures ~ include instrument uncerta.in ties 4

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DESIGN CONSIDERATIONS FOR OPERATION AT HIGH BAY TEMPERATURES e Add Safety-Related Air to the Diesel Generator SRW Control Valve To be completed by first week in July o Credit Actual SRW Pump Performance Engineering Test Procedures completed in May Limited to Nos. 11,12,21, and 22 SRW pumps e Reduction in Power Reduction to 80% power history Eliminates post-RAS performance limitations 28 Wu- w ==w umw + v- v __g mm *t s-ws*w-ens--+1m.m er, * - v e , e e m e m e s e e w' n --w w ee sw sv w w w e -t e + w w- -e*-9++ue- , - m=1W wr' ? *T +veg we-t e a w y ure m geo-e== g ,y e e-y + ,. . .

DESIGN CONSIDERATIONS FOR OPERATION AT HIGH BAY j TEMPERATURES i _ _ _._

l l e Isolation of One CAC

Reduces system heat load by ~40%

Significant increase in operating limits i

l Diesel generator and. emergency core cooling i system train remain operable i

j e Credit Bulleting 'with Reduction in Fouling i Resistance Credit less than equilibrium microfouling for short l

period after bulleting 5

29

=

l LONG-TERM ACTION

. emmem_m_

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l e Service Water Heat Exchanger Replacement Replace SRW Heat Exchanger with plate heat

) exchangers Provide saltwater strainers to minimize j macrofouling i

e Schedule i Unit 1 - 1998 RFO

3 Unit 2 - 1999 RFO l

l

' 30 l -

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LONG-TERM ACTION m.m.m. .

e Plate heat exchangers were designed with large margin Specified for 90oF Bay temperature Sized for power uprate Sized for steady heat load at maximum LOCA value Designed with ~15% expansion capacity Sized for the maximum recommended fouling factor for water conditions 31

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LONG-TERM ACTION

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o Plate heat exchanger SSM is in operation now to provide fouling data prior to implementation of the mod E

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j Background and Available Actions l

i l J. L. Gines - System Manager l

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OVERVIEW 2scuce:vremenenm w.a c .

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l e Historical Background Actions taken in 1995 vs.1996 Chemicals attempts to add margin: Clamtrol Maintenance Rule e Actions Managing Delta P (1997)

Schedule Environmental Considerations 34 1_

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i 1995 vs.1996

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! e1995

) Hot (>88oF peak), dry year (~30 days without rain)

Low Oxygen (Red Tide), high salinity i High Bay temperature and assumed fouling a challenge
- Per SSM data, microfouling stopped during high temperature and low oxygen Conditions!

j Minimal macrofouling, challenged by low allowed Delta P due to temperature I

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1995 vs.1996 l .

l e 1995 continued l A very challenging Summer

) - highest temperatures recorded in the Bay l - led to first ever Saltwater initiated power reduction

(~1 week) e As a result, the strategy for 1996 was to i minimize microfouling i PLAN to bullet every 2 weeks, as required

)i - decreases maximum microfouling l

1 1

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1995 vs.1996

= ,= , - - - .

e1996 ,

Relatively cool (~83oF peak), wet year High Oxygen, low salinity Conditions contribute to high macrofouling in certain headers

- Recurvum mussels-Heat exchanger bulleted every two weeks, for

~ 2 months, leading to high unavailability and operational challenges 37

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CLAMTROL g .g_J9*r=*nrtvs vtxy y aq i

l e Intended to reduce microfouling in tubes l

i e Be easy to apply

! Once per week manual skid injection: no hard j piping or automatic controls l e Limited use in 1992. , and 1994 indicate that it 4 . .

is effect.ive at inh..ioi. ting bacten. a l growth i

i 38 I

4

l i

i

~

, CLAMTROL l

e Side Stream Monitor studies in 1995 and i

1996 conclude that to be effective at

controlling microbiological fouling

Must be initiated soon after heat exchanger bulleting Must be applied ~ daily Will not remove established fouling Optimum concentration above State permit limit

._ 39

_ W1W-M= $*ww'7' *wmne'-9 P' gywy wytg g wg-w y aw q wv-3 + 7TP w g e wvw werew y gww wg r+wy.__ wg-gwmW M* twNWW WW*_ ,'TetD*Fv4"4WW W M -W M -W"VPW*4" "TT*

T'*N'W*W*T"W"*N*-#***

1 MAINTENANCE RULE i

e No saltwater header went into an (a)(1) condition primarily as a result of two week bulletings in the Summer of 1996 Less bulleting expected in 1997' '

c e Risk evaluated for each evolution

) e Unavailability tracked by System l Manager / System Engineer l

e Unavailability managed by the Quarterly

! Surveillance Schedule process 40 l.

I

! ACTIONS -- MANAGING

, DELTA P (1997)

"'iCM!MEX&'iTJ$ic'M w :

i i

l e Manage Delta P by tubesheet cleaning, not l bi-weekly bulleting i

j Indefinite Flow / Delta P/ Temp curves will be used ,

i - Assumes maximum microfouling Less header downtime, greater availability 1

i 1

"Recently Bulleted" Curves ready to use on an i

operability basis i

l l

l i 41

ACTIONS -- BULLETING

. - ,=. ,, = _ = _ g e Scheduled bulletings

, Two per header scheduled for this summer, to allow scheduled maintenance Not additional buiietings,2 of the 4 normally scheduled bulletings moved into the summer 42

, , , , , , _ _ _ _ -_-- - - - - " ' - - - ^ ' - - ~ ' - -

l l

l l -

l ACTIONS -- BULLETING t

l e Non Scheduled bulletings l Performed "As required" based on inability to

!; maintain Delta P within limits after tubesheet l

cleaning Limit scope of work to bulleting, to reduce maintenance challenge May be performed preemptively, if conditions leading to high bay temperatures are expected 43

~ w

i 1 , ~

1 ACTIONS -- SCHEDULE

_._ murmeer.nm I

e Clean saltwater tunnels

(Unit 2 during 1997 outage; Unit 1 by 7/19/97) l - Reduces macrofouling going to SRW Heat Exchangers

) e Safety-related air modification to Diesel Generators

! (completed by 7/2/97)

I - Increase allowable Bay temperature by 1oF l

1 e Optimize baffle wall configuration j (done)

! - reduce recirculation of Plant discharge 44 I~

. , ~ , . . , , - _ , , , . , - , , . , - , . - . . , . - - , , - ~ . . - _ . . . . . , _ . , _ , . . . - . , , , - , - , . . _ , . , - , _ , , , , _ ,

4  :

i i ENVIRONMENTAL CONSIDERATIONS ws exxunuga w--

o Environmental conditions will be monitored by '

l Operations and Auxiliary Systems l

s Engineering Unit to ensure ali actions are l appropriate i

1 l

4 s

! 4

.i u .

45 i e

-,g ,.-.w-w.,-, , - - - - --,.,%,,---,4, .-.,-w.,,, or,- ..,.,,%,...,-w.-wm e s , - w,%,,,-w % ,%,,,g..,.w-r...,-.m,-...ww%,-y-, , , . _w,,w,._,-_

l l

i ENVIRONMENTAL CONDITIONS TENDING l TO INCREASE BAY TEMPERATURES i ..-... m =,m m _ .

i i

! -Mid afternoon high or low tides l e " Slack water" conditions lead to recirculation of Plant j discharge

! -Winds from the East, particularly 060 to 090 e Recirculation of Plant discharge l e Warm surface water pushed toward Plant j e See next slide " Plant Layout" l -Clear high temperature, high humidity days

e Reduced evaporative cooling l -Extended periods without rain l

j, 46 i

,......-. _ , ,_ , ,, ,--_._ _.-. , _ ._-..- -.~.- _.. - ,,- ~ .-

PLANT LAYOUT n n. = w . m=:- ,.. . ,

Chesapeake Bay l',"c i

i 8 45 j Rant Plant -114mL

Discharge, \

!, s\

s r I

\\

} \\ [ Baffle wall 1

\\

i

\\

s l Shore line t

+--intake Structure

.i l

I OO1I U1 U2 l QQ '&

4 47

~

4 o

i I

i ENVIRONMENTAL CONDITIONS TENDING

< TO DECREASE BAY TEMPERATURES M *W :e *$E N ? h t.? L'A h T 5 W + *- .

i i

! - Rain

! e Cools the Bay

-Westerly winds

. o Opposite of Easterly winds, pushes warm surface

! water away from Plant '

i

-Overcast, low humidity days, Clear nights e Increases evaporative cooling i

i 48 I

i l ,

I l

> ENVIRONMENTAL CONDITIONS TENDING ,

i 4

TO INCREASE PRESSURE DROPS m &-w-r'c v ><,; '.*'tr- ,e;;:r;3; g g i

i l

l -Thunderstorms l e May loosen macrofouling from baffle walls, allowing it ,

j to enter the Plant j -Cycling sluice gates j e May loosen macrofouling j

I

?

9 1

j 49 C _ .. ._.. . _ _ _ ._ _ _ _ . _ _ _ _ . _ . ._ . _ _ _

i I l

}

l

< ~~ ~ "2 m rcbn M:av s "

l Operational Options l M. T. Navin - General Supervisor, Nuclear Plant Operations i

i 50 3

. - , - , , - - - - . ~ . . , . , . , . . . , , , . . . . - - - , - - - - - - - . . . . - , - . - . _ _ _ _ ._ - , . . . _.. _ . - _ , . . . . - , . .

PROBLEM IN MID-JULY AND AUGUST

. _ . m m . _ ,s . _

High Bay Temp -

Summer 1995 High Delta P -

Summer 1996 T'emperatures can swing about 5 degrees per day during a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period.

51

1 . .

l

! COMMON STRATEGIES

- , . . s e .. e. . r, c - .c:f.. g : .:

l l e Track maximum temperature, maximum l delta P limits, current bay temperature, and -

! delta P values by saltwater header

o Take above readings each shift o Clean saltwater tunnels l e Safety-related air to diesel generator SRW
control valve

! e Optimize baffle wall configuration e Determine next option - clean, bullet, isolate a CAC, or reduce power?

52 i r

1 SERVICE WATER OPERATIONAL i LIMITS i ._ .m mmmm - -

! Maximum Maximum l Header Temperature Delta P 11 89 2.88

! 12 86 2.98 4 21 86 2.94 i

22 86 2.82 l

Totally clean gives approximately 2.5 psid (after

bulleting) at 18,000 gpm.

l Includes effects of CAC SRW stops, diesel generator i

control valves, and Nos. 11,12,21, or 22 SRW pump j 53 i

t

,,,m__, e-. . 6-____ ,,.. ,,~.,,,..-,_w....,._mmmm._,m.-,..,,,,,m-,.-,__,,,_,,,,,,_..,,,,-.m.m.wm.....,.......,__e,

k OBJECTIVE IS TO MAINTAIN

! NUCLEAR SAFETY

.>m . sw.;; cat .rema:u e ..

i l Options to Gain Additional Margin l Power reduction to Gain 1.0oF or 0.25 psid

) 80% power

Bullet Heat Exchanger Gain 2.0oF or 0.5 psid within 7 days Isolate 1 CAC - Allow max 90 degrees l

. Manual (When saltwater and 5 psid on header i header is OOS) with CAC isolated Shut down reactor and cool down to Mode 5 if i

temperature exceeds 90 degrees.

j Cleaning the heat exchanger tube sheet maintains the j .

onginal criteria. 54

l.

i l CLEAN SERVICE WATER HEAT l

EXCHANGER TUBE SHEET

~ w A23..nw': ars:nv n.= ' ;

e Advantages l Minimize OOS time (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />) l e Disadvantages 4

l Renders Saltwater Header, Diesel l Generator, and CAC OOS Does not restore to base line delta P like bulleting j Diminishing returns via cleaning

! Operations still must maneuver system 55

l l

REDUCE POWER

u. - 12ry yt'i;;:r:;t2:'y w.; , ..

[ o Advantages

! Gains 1 degree margin (except on i

i 22 header 11 i

l e Disadvantages i

l Drop power 10% per hour to 50%; Increase l power to 80% in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />; 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> total j required

Plant must be maneuvered over 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />  ;

i 8

i

. - . . , . _ . - , , , . _ . . . . . ~ . _ . - . , _ . _ . - . . . _ _ _ _ , _ _ _ -

i l

4 BULLET SERVICE WATER HEAT EXCHANGER l e Advantages l Clean base line for minimum delta P l Gives additional 2 degrees margin for j 7 days j Would also allow time to clean saltwater j tunnel

e Disadvantages l

Renders Saltwater Header, biesel Generator, and CAC OOS Operations still must maneuver system 57 Longer OOS time to bullet

- . . - . . - . . . . - - _ . . . . . . _ , _ _ . - . . _ ~

i l CAC ISOLATION WHEN SALTWATER .

l HEADER OOS ,

--m_m - _

l e Advantages I Maximum 90 degrees on Saltwater i

Header that has 1 CAC isolated j Increase delta P from approximately i

4 3 psid to 5 psid

] Safer than securing the entire header ,

) -

Entire emergency core cooling system train and l emergency diesel generator remain operable

) -

Securing a CAC is not a challenge to Operations i

I u

l 58

}

L_..__...-.--_.__.._. _ . . . _ _ . _ . _ . . _ _ _ _ _ . _ _ - - . _

! CAC ISOLATION WHEN SALTWATER

HEADER OOS e a wm ~ me z a,n ,~ . .. .

l e Advantages Safer than securing entire header

' - Probabilistic risk assessment (PRA) risk better Saltwater Header OOS (4.15x) vs.1 CAC OOS (1.02x)

- Probabilistic risk assessment results for i

containment failure scenario l 2 CACs OOS (s 3x)--low risk i

2 CACs and spray pump (> 3x)- medium risk i

i 59

t CAC ISOLATION WHEN SALTWATER HEADER OOS  ;

m,.m, _ m. . _ _ _ _ _ _ _ _ _ _ _ _ _

e Disadvantages Containment air cooler not operational (but there is defense in depth) 60

. o i

HIGH SALTWATER TEMPERATURE / LOW i

SRW HEAT EXCHANGER DELTA P amax .:. : 8., - n u ;e :-. :: . '; ,>;g ,e *,.iM i

l Strategies e Bullet 1 SRW Heat Exchanger per Unit every

) 7 days, as needed i

i e Power Reductions i

! e Header OOS on high temp --isolate 1 CAC l per unit and bring the affected header back to l operable status -- Supports Plant Safety i

i

! 61 I ,

]

0 HIGH SALTWATER TEMPERATURE / HIGH SRW HEAT EXCHANGER DELTA P

_ - - - , ,= - -

Strategies e Clean SRW Heat Exchanger e Bullet SRW Heat Exchanger, as needed j e Header OOS on high Delta P --isolate 1 CAC

! per unit, call Header operable to support PRA l as required (i.e., Auxiliary Feedwater Pump OOS and l

Saltwater Header OOS - medium or higher PRA. This option l would keep PRA low.)

i l

62 l

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