ML20198H425

Forwards 90-day Response to GL 97-04, Assurance of Sufficient NPSH for ECC & Containment Heat Removal Pumps. Rept Provides Assurance That NPSH Issues Are Being Adequately Addressed by TVA

ML20198H425
Person / Time
Site:	Browns Ferry
Issue date:	01/05/1998
From:	Abney T TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-97-04, GL-97-4, NUDOCS 9801130288
Download: ML20198H425 (15)

Text

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Teormee vaney Auttaity, r%t once nam ma. twatur, Natur.s no ma January 5, 1998 U.S. Nuc1 car Regulatory Commission 10 CFR 50.54 (f)

ATTN!- Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of ) Docket Nos. 50-259 Tennessee Valley Authority ) 50-260 50-296 BROWHS FERRY NUCLEAR PLANT (BFN) - RESPONSE TO NRC GENERIC LETTER (OL) 97-04, ASSURANCE OF SUFFICIENT NET POSITIVE SUCTION HEAD (NPSH) FOR EMERGENCY CORE COOLING AND CONTAINMENT HEAT REMOVAL PUMPS On October 7, 1997, the Nuclear Regulatory Commission issued the refsrenced GL regarding degraded performance of Emergency Core Coolant System pumps. The GL requested that TVA review the design basis accident (DBA) analyses used to determine the available NPSH for the ECCS and containment heat removal pumps that take' suction from the suppression pool following a design basis loss of coolant accident (LOCA) or secondary line break or pumps used in operation that are necessary for recirculation cooling of the reactor core or containment.

The information contained in this response provides assurance that HPSH issues are being adequately addressed by TVA. This letter providea TVA's 90 day response to the subject GL.

f 9801130288 900105

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. U.,S. Nuclear. Regulatory Commission '

Page 2 January 5, 1998

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Unit 1 is shutdown defueled and on administrative hold with  :

no established restart date. Therefore, TVA will evaluate the impact of NPSH for emergency core cooling and containment .

heat removal pumps on Unit 1 prior to its restart 8.  !

Accordingly, this letter will focus on activities necessary tofensure the design basis of Units 2 and 3 ECCS pumps.  !

By letter. dated July 25, 1997, (Reference 1), TVA provided a reply to NRC Bulletin 96-03 which outlined proposed actions

• for resolution of NRC'S concerns for loss of ECCS following a DBA-LOCA. To ensure adequate NPSH is maintained during a LOCA, TVA proposed the installation of larger capacity passive strainers, taking credit for an overpressure in excess of atmosphere. Overpressure is required only for a short period of time. The requirement for overpressure is ,

driven by assumptions made to satisfy NRC Bulletin 96-03 debris concerns. ,

in the Fall of 1997 during a scheduled refueling outage, TVA ,

installed the replacement strainers in Unit 2. TVA will replace the strainers in Unit 3 during the refueling outage 8 scheduled for the Fall of 1998 . Therefore, the information contained in this 90-day response will refer to both the existing design basis for NPSH as well as tne subsequent calculations performed for the proposed resolution of MRC Bulletin 96-03 concerns. The calculations for NRC Bulletin 96-03 have been prepared and checked but not yet formally issued pending NRC approval of the minimum overpressure. <

By letter dated August 25, 1997, (Reference 2), TVA informed the staff that a license amendment is required in order to take credit for contr.inment pressure in excess of atmosphere  !

in order to meet NP'. H requirements incorporating debris t assumptions of Urm Bulletin 96-03. TVA is in the process of

~ preparing a license amendment incorporating the use of containment overpressure into the BFN licensing basis. The amendment request will reflect the overpressure results contained in this response, along with the required analytical details to support minimal overpressure ,

Conclusions.

I this commitment was identified as ratt et the october 31, 1991 letter, As such, no new comrattaant has teen estabitsbed.

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This comattant, was toontatted as part of the hty tt,1991 letter. As such, no new cumitanent has ,

bDeh oftablishd.

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, U..S.' Regulatory Commission- l Page 3- -1

. January 5, 1998, j-.

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. ? ..j This'lettet coistainsino new NRC commitments on this matter. ~!

If-you have'any questions regarding this please contact me at' j

-(205) 729-2636. -:

'S/ ice 1, . 1 >

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t T.E.- 'ne Manager of Lie -i and. Indust Affairs -i

'i Subscribed a sworn before'me on this:Sth day of:

January,-1998.- l O dW My commission expires 10/UAffe.

tt h b Enclosure .;

cc (Enclosure):  ?

Mr. Albert W. De Agazio, Project Manager i U.S.: Nuclear Regulatory Commission' One White Flint, North 11555 Rockville Pike- 9 Rockville,= Maryland 20052 l Mr.-Mark S. Lesser, Branch Chief U.S. tiuclear Regulatory Commission Region II:  !

61 Forsyth Street, S. W. -l Suite 23T85 j

Atlanta, Georgia 30303

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NRC. Resident Inspector - -

f Browns Ferry Nuclear Plant 10833 Shaw Road

-Athens,-Alabama ~ .35611-j

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.. I ENCI48URE TENNESSEE VALLEY AUTHORITY BRONHS FERRY NUCLEAR PLANT (BFN)

UNITS 2 AND 3 RESPONSE TO NRC GENERIC LETTER 97*04, ASSURANCE OF SUFFICIENT NET POSITIVE SUCTION HEAD FOR EMERGENCY CORE i COOLING AND CONTAINMENT HEAT REMOVAL PUMP 8 i

The purpose of this enclosure is to provide TVA's response to the i requested information in NRC GL 97-04. The GL requests that TVA  ;

. submit information necessary to confirm the adequacy of the net j positive suction head (NPSH) available for emergency core cooling '

(including core spray and decay heat removal) and containment '

1 heat removal pumps. The request pertains to pumps that tal:e suction from the suppression pool following-a design basis loss of coolant accident (LOCA) or secondary line breal: or pumps used ,

in operation that are necessary for recirculation cooling of the  !

reactor core or containment.

This enclosure will focus on the design basis net positive  !

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suction head (NPSH) requirements of Units 2 and 3 Residual Heat Removal (RHR) system and Core Spray (CS) system pumps. Unit 1 is i

shutdown, defueled and on administrative hold with no current plans for restart. Therefore, TVA will evaluate the impact of NPSH for emergency core cooling containment heat removal pumps on Unit 1 prior to its restart 2 i

Specific Requested Information And TVA's Response NRC Request 1 Specify the general methodology used to calculate the head loss associated with the ECCS suction strainers.  ;

TVA Response r The not positive suction head available (NPSHx) at the pump ,

suction nozzles is a function of the system configuration, system

. pressures, flow rates, elevational differences, and other head

. losses. The following-provides a description of the BFN emergency core cooling systems (ECCS) and summarizes the NPSHa analysis.

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ECCS DESCRIPTION The Browns Ferry ECCS configuration includes an ECCS ring header circumscribing the suppression chamber with connecting piping to four inlet penetrations through the torus wall into the suppression chamber. Inside the suppression chamber, each connecting line is fitted with a flanged surface for mating to the ECCS strainer flanges. The ECCS ring header is the normal suction source for the low pressure RHR and CS System pumps and the alternate suction source for the High Pressure Core Injection '

(HPCI) and Reactor Core Isolation Cooling (RCIC) System pumps.

The normal suction path for the HPCI and RCIC System pumps is the Condensate Storage Tank. The HPCI and RCIC systems are only used short term during a large break LOCA; therefore, are not considered critical to long term NPSH considerations.

The four strainere direct ECCS flow to a common ring header. The common ring header supplies water to two loops of RHR (2 pumps per loop) and 2 loops of CS (2 pumps per loop). The range of suppression pool temperatures for design basis events is from 95"F to a maximum temperature of 177 F.

The original licensing basis analysis for the plant design includes four, 1/8 inch mesh cylindrical strainers that take suction on the suppression chamber. As described in TVA's July 25, 1997 submittal (Reference 1), DFN has installed new high capacity strainers in Unit 2, and will install in Unit 3 new high capacity strainers.

NET POSITIVE SUCTION HEAD ANALYSIS The following discussion is based upon the current licensing basis analysis with notation of the differences in the analysis performed in response to NRC Eulletin 96-03 concerns as described in Reference 1.

The NPSHA is defined ast NPSH3 = h. + h. + h y, + he where

h. = air space absolute pressure (in feet of water) in the suppression chamber on the surface of the water. The licensing basis analysis uses a constant pressure equal to one standard atmosphere with the air at equilibrium temperature with the water,

b. = static (i.e., elevational difference) suction pressure

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• i (in feet of water): between.the water, surface in'the suppression chamber and the'ECCS pump. suction nozzle.  ;

Positive qu0ntitles represent a waterfsurface above the i pump-nozzie. The suppression chanber water level is  !

based on the Technical Specification 3.7.A'.l.a, the; I

= minimum level value with zero pressure differentia 1' ,

between the drywell and suppression chamber.- a h,p w vapor pressure (i.e., saturation pressure of water) (in  !

feet 1of water) at the bulk temperature of the. 1 suppression. pool. Since the water temperature changes  !

. 'during the-courte of an accident, this parameter is a ,

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-function of time as discussed in the response to NRC Request 2.. . .,

i i< hr = pressure drop (in feet ofLwater) due to the piping 1 system configuration and condition. Additional f

discussion of this term is provided below.  ;

The pressure drop due to the piping system configuration and l condition is based upon the limiting RHR/CS loop considering. -,

piping length / configuration, flow components and suction 1 strainers.

The' piping length evaluated is conservatively based-on the loop i with=the longest length from the suction strainer-inside the  !

suppression chamber to the pump nozzle. . The licensing basis analysis assumes a pump loop-draws'all of its suction from the strainer nearest its ring header connection; However, an analysis of the ring header flow demonstrates'that_the flow will  :

actually originate approximately equally from each of the four

-strainers (dependent on differential blockage). Assuming the:  ;

c flow comes from'only the nearest strainer maximizes the frietional pressure drop due to the higher flow rate in that ring q header section, j The pressure drop analysis considers the number and type of

_ piping' components (e.g., elbows, tees, valves, etc.) present in the line'and utilizes standard pressure drop methods and values.

Entrance losses-for the suction strainer in addition.to the pressure drop associated with strainer blockage are included in .

Lthe analysis. The-ECCS is filled with demineralized condensate  !

squality waters.thus,Lno-pipe.. aging is included. - Consequently,  ;

clean commercial steel pipe for the determination of friction  ;

_ leases;is alsoLassumed. Jul informal sensitivity study was ,

performed with friction factors' higher than those used for clean 1 '

pipe.:,The results-indicated.the potential increase in line .

losses to beiinsignificant.

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l The original suction strainers.are cylinders made of perforated  ;

t sheet steel. The strainer pressuro drop was calculated using theoretical equations for various percentages of_ strainer blockage. Strainer holes are assumed to be either completely blocked or completely open. The analysis considers the fraction

• of the strainer surface containing holes. Blockage in the current analysis is assumed to occur solely due to unqualified coatings-inside containment that disbond following an accident. '

The coatings are transported to the suppression pool-and ultimately to the strainers.

i An analysis of the dynamics of_ coating chips was performed to determine the amount of unqualified coating which would be transported-to the strainers. The analysis assumes the initial ,

violent phase (i.e., drywell venting) of a LOCA is over and the <

pool has stabilized with zero pool velocity. The analysis calculates the path of coating particles entering the suppression pool and determines the fraction of coating particles that would  :

be drawn to the strainers. One hundred percent of the  ;

unqualified coatings are assumed transported to the suppression pool through a uniform distribution of coating particles to each 1 of the 96 downcomers. None of the qualified coatings are assumed to disbond from the coated surface during or following the accident.

Since the coating particles have a high density relative to water, particles that are not drawn to the strainers are assumed i to be deposited on the suppression pool floor and are no longer available for interaction with the strainers. The size of the particles are minimized to conservatively decrease the settling i velocity. The particles are assumed equal to the strainer hole size since smaller particles would pass through the strainer and

• not contribute to blockage. The analysis does not consider very thin coatings since they are too fragile to withstand the differential pressure across the strainers and thus will pass  ;

through. ,

The methods employed by the current analysis are as follows: The pressure drop analysis assumes the NPSH required (NPSHa) is equal to the NPSH3 and determines the pressure drop available for the ECCS suction strainers and hence the amount of unqualified coatings which could be present inside primary containment. The amount of unqualified coatings inside primary containment is controlled to ensure adequate'NPSHA for the ECCS pumps.

The new analyses performed in response-to-NRC Bulletin 96-03 utilizes the BWR Owners Group (' O G) Utility Resolution Guidance (URG)- methodology for the determination of debris loading on the high' capacity strainers and then determines the NPSHx versus E-4 y- -.p.~ ~ - . _ . _ . ..._..pq__. ,

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NPSHa using the theoretical piping system pressure drop methods described above. The discussion of the debris loading is detailed in Reference 1.

As previously discussed, the current design methodology for suction strainer losses assumes a pump loop draws all of its suction from the strainer nearest the ring header. TVA's proposed analysis for resolution of concerns addressed in NRC Bulletin 96-03 explicitly includes the entire ring header. .The proposed calculations are conservative in that at time equal to zero, the calculations assume that Reflective Metal Insulation has been deposited on the strainers to a saturation thickness.

The analysis supporting NRC Bulletin 96-03 for Units 2 end 3 utilizca a h. in excess of atmosphere. The existence of the overpressure in excess of atmosphere for the applicable events was verified by containment pressure analyses using assumptions to conservatively minimize the containment pressure during a DBA-LOCA. It should be noted that the overpressure discussed is required for a short period of time.

NRC Request 2 Identify the required NPSH and the available NPSH.

TVA Response The NPSHa versus the NPSHA for the RHR and CS systems are shown in Table 1 for the current licensing basis analysis and Table 2 for the analysis to support the resolution of NRC Bulletin 96-03.

It is noted that the values in Table 2 are slightly different than those discussed in Reference 1 as explained below. The changes have been made to more accurately reflect the response of the plant to LOCA conditions. Therefore, this table supersedes Table 1 of the July 25, 1997 letter. The following provides a discussion of the basis for the values in both the current analysis and the new analysis.

TVA's limiting short term analysis assumes that the flow of two RHR pump's is being directed into a broken recirculation loop and subsequently to the drywell. Flow from the other two pumps is being injected into the unbroken recirculation loop and subsequently into the reactor vessel.

During the first 10 minutes of the LOCA event, all automatic RHR and CS pump starts are assumed to occur and operate with a total design flow rate of 54,500 gpm across the ECCS strainers. To maximize strainer flow, it is assumed in the current licensing basis analyses, and for the results reported herein for the new E-5

analyses that-at initial pump start, 2 RHR pumps (one loop) are at runout flow (11,000 gpm per pump), 2 RHR pumps'(one loop) are at. design flow (10,000 gpm per pump), and 4 CS pumps (two loops)  ;

are at design flow (3,125 gpm per pump) . The RHR system has flow ,

limiting orifices in the pump discharge lines that limit the runout flow to 11,000 gpm. Another conservative case is .

evaluated in the original licensing basis calculations with all eight pumps at runout flow with the suppression pool _ at 130 F.

The results reported in Reference 1 for both the initial pump start and at a condition of suppression pool temperature of 150*F assumed that one loop of CS was at runout conditions. However, ,

unless the break is in the CS piping, the CS system will be pumping into-the reactor vessel and will not experience runout conditions. Therefore, the initial pump start-case reflected in Table 2 herein utilizes only CS design flow. For this same

. reason, the case reported by Reference 1 at 10 minutes with a CS loop at runout conditions has been deleted.

The long term limiting containment analysis (after the first ten minutes of the LOCA event) models a doubic-ended recirculation  :

suction line break with no offsite power and the failure of one emergency diesel generator. TVA calculations, which are consistent with the BFN Emergency Operating Instructions (EOIs),

assume that at ten minutes into the DBA-LOCA, manual operator actions secure ECCS pumps not required for core cooling and align RHR into the suppression pool cooling mode. The BFN EOIs, which are symptom based, require' establishing long term cooling requirements upon reaching a preset reactor vessel level. During simulator scenarios, actions to establish long term cooling occur prior to ten minutes. Hence, the assumptions made in DBA-LOCA analysis for NPSHA are validated through simulator scer.arios.

The minimum long term flow required for accident analyses is 2 RHR pumps on ene loop at design flow in the containment cooling mode (5,500 gpm per pump) and 2 CS pumps at design flow providing injection to the reactor pressure vessel (3,125 gpm per pump) for  ;

a total flow of 19,250 gpm.

The NPSHa is based on the pump manufacturer's data for both the RHR and CS system pumps. The NPSHa is specific to each pump type and is dependent upon the flow rate being evaluated. TVA' s current license basis for primary containment dictates that Ladequate NPSH for the RHR and CS pumps will be available without dependency on. containment overpressure. Although not included in TVA's resolution of NRC Bulletin 96-03 concerns, BFN test data '

(Reference 3) demonstrated that the RHR pumps can be operated for short periods of time at values much less than the manufacturer's NPSHa without degradation. This test information is applied to E-6

the first two cases in Table 1 for the current licensing basis analysis.

The NPSHA is dependent on the number of pumps operating and their flow rate, piping system configuration and condition (as described above) and the suppression pool temperature (vapor pressure) at the containment conditions being evaluated. The current licensing basis analyses related NPSH solely to the I amount of unqualified coatings inside primary containment. The analyses performed in response to NRC Bulletin 96-03 utilizes the .

BWROG URG methodology for the determination of debris loading on the strainer.

The BFN licensing basis analyses are based on the assumption that NPSH is equal to NPSHx and then determines the percentage of strainer blockage allowed and hence the amount of unqualified coatings which could.be present inside primary containment. The amount of unqualified coatings inside primary containment is controlled to ensure adequate NPSHA for the ECCS pumps.

The analysis proposed for resolution of NRC Bulletin 96-03 concerns utilize the Owners Group strainer blockage assumptions and then determine the NPSHx versus NPSHa.

The vapor pressure of the water and the pump / flow conditions in the approved analyses are based on those conditions shown in Table 1.

Table 1 contains the results of the analyses of percent strainer blockage allowed for each case. From these results it was concluded that adequate NPSH would be available if the strainer blockage was limited to 65%. It is noted that one case (Core Spray at initial pump start) shows an allowable blockage of 50%

which is less than the 65% criteria. At initial pump start, tha unqualified coating would not have had time to delaminate from its substrate and be transported to the strainers. Therefore, this case was not considered limiting.

Table 2 provides a comparison of limiting plant descriptions and proposed NPSH requirements at the pump for selected analyzed plant conditions utilizing a pressure above atmosphere.

NRC Request 3 Specify whether the current design basis NPSH analysis differs from the most recent analysis reviewed and approved by the NRC for which a safety analysis has been issued.

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TVA Response The design basis NPSH analysis does not differ from the most recent analysis reviewed and approved by the staff for which a safety analysis (Reference 4; has been issued. The design basis does not include pressure in excess of containment atmosphere in order to meet CCCS NPSH requirements. In a letter issued by the Atomic Energy Commission on June 28, 1974, the staff concluded that adequate NPSH for CS and RHR could be maintained with no dependency on containment overpressure.

As described in the UFSAR, during the initial design of BFN, the sizing of the strainers in the torus and pipes connecting the suction header was conservatively based on the assumption that at least one of the four strainers is completely plugged during a postulated accident. This could only occur if a large object such as a sheet of plastic were present inside containment. The BFN Foreign Material Exclusion program minimizes the potential of this occurrence. Furthermore, recent analyses have demonstrated that the flow around the ECCS ring header will be capable of supplying the flow to any of the ECCS systems even if the strainer nearest the system penetration to the ring header is completely blocked. Therefore, complete blockage of one strainer is not considered a limiting condition.

Design basis calculations support adequate NPSHA with all four original strainers clogged approximately 65 percent due to uncontrolled coatings. As part of the resolution to NJC Bulletin 96-03 concerns and its associated debris loading requirements, TVA has determined an available overpressure in excess of atmosphere will be necessary to meet RHR and CS pump NPSH requirements (Reference 1).

NRC Request 4 Specify whether containment overpressure (i.e., containment pressure above the vapor pressure of the sump or suppression pool fluid) was credited in the calculation of available NPSH.

Specify the amount of overpressure needed and the minimum overpressure available.

TVA Response The current licensing basis for BFN does not credit containment pressure above the vapor pressure of the suppression pool in the calc tion for available NPSH. However, TVA's proposed Jesign for th resolution of NRC Bulletin 96-03 relies on available containt ent pressure in excess of the atmospheric pressure in order to meet RHR and CS pump NPSH requirements (Reference 1 E-8

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and 2)'. Table 2 provides pump NPSH requirements for the proposed BFN analysis in support of the. resolution of NRC Bulletin 96-03 relying on containment overpressure.

NRC Reelest 5

When containment pressure is credited'in the calculation of available NPSH, confirm that an appropriate containment pressure analysis was done.to establish the minimum containment pressure.

WA Response The current licensing basis HPSH calculation:does not take credit:

for available containment overpressure. As described in-Reference 1. containment overpressure will be required to be utilized to resolve'NRC Bulletin 96-03. .A minimum overpres'sure

• analysis:was. performed to insure adequate overpressure exists when credit =for overpressure is needed. Details.of assumations made (containment leakage, containment- spray, etc.) will ;ae contained in the forth coming BFN License Amendment. The-assumptions for the new analyses relative to the minimization of containment overpressure are contained in Reference 1.

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TARTI 1 RER AND CORE SPRAY PUMP NPSH CASES WITdvur CREDIT EDR OVERPRESSURE -

• CURRENT LICENSING BASIS PRR PUMP RHR FUMP AIJ~ WIZ CS FUMP C5 Ft2tP ALLOMABLE PRR FUMP NPSH NFSH STPAINTR CCRE SPPAY CCPI SFPAT NPSE NPSH STPAINER' FI4rd PRR FUMP REQUIFY.D AVAIIABLE BLOCEAGE FUMP TLCar FUMP FI4Mr PICUIRED AVAIIABLE BLOCFAGE CCNDITION FLOW PATE (FEET) (FEET) (FEFCENT) CONDITICN PATE (FEET) (FEET) (FERCENT)

Ieitial ECCS 2 pu: cps on 11,000 gpm 21' 21' 72 %* 4 pumps 9 3,125 gpm 35' 35' 50%

Stort-Maximum one loop 9 (x2) design flow (x4) flow in one runout 22,000 gpt Total riow PRR loop, and 2 pumps plus 10,000 12,500 gpm Suppression on one loop gpm (x2) pool 9 design 20,000 gpm temperature flow (in Total Flow 102. 5'T LPCI Mode) 42,000 epm Within First 2 pu=ps on 11,000 gpm 21' 21' 71% 2 pumps on 4650 GFM Not Not Not 10 minutes, two loops 9 (ze) each loop 9 (x4) Analyzed Analyzed Analyzed maximum flow runout (in Total riow runout flew 18,600 GPM in br>th loops LPCI Mode) 44,00c gpm of RHR and CS.

Suppression Pool at 130*F At 10 2 pumps on 10,000'GPM 26* 26' 824 2 puz:ps on 3,125 gpm 26' 26' 84%

minutes, flow one loop (in (x2) one loop 9 (x2) 6,250 reduced to LPCI Mode) 20,000 GFM design flow gpm long term at design -

requirements. flow Suppression Pool at 140*r Long Term 2 pumps on 6,500 gpm 24* 24' 82% 2 pu=ps on 3125 gpm - 26' 26' 65%

ECCS pump one loop at (x2) 13,000 one loop 9 (x2) flows at peak design flow gpm design flow 6250 gpa torus (Containment teieperatures m ling)

(177'r)

I over two or tt existin, strain.rs r. consis t.a campi.tely obstact.a.

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TABLE 2 RHR AND CORE SPRAY Pt.MP NPSH CASES WITH CREDIT IVR 2 PSIG OVERPRESSURE ~ *

, NRC Bulletin 96-03 S**=mi ttal Requiremments -

PRR FUMP RHR FUMP .

CS PUMP CS PUMP NPSH NPSH CORE SPFAT. CCRE SPRAY. NPSH NFSH RHR PUMP FLOW PRR PUMP FLOW PATE REQUIRED AVAIIABLE PTMP FLOW PUMP FLOW RMIRED AVAIIABLE 3

CCNDITICN (FEET) (FEET) CONDITION PATE (FEET) fFEET)

Initial ECCS 2 pumps on one 11,000 gpm (x2) 30' 32.05 2 pumps on 3,125 gy 27' 35.77'

Start-Maxi wem .

loop 9 runout 22,000 gpm each loop 9 (x4) flow in one RHR and 2 pumps'en plus 10,000 gpm design flow 12,500 gym loop and design one loop 8 (x2) 20,000 gpm flow in other RHR design flow Total Flow and C5. loops. (in LPCI Mode) 42,000 gpa j Suppression Pool 9 95'T Within First 10 2 pumps on one 11,000 gpm (x2) 30' 30.39'* 2. pumps on 3125 GPM 27' 34.1**

minutes, LPCI loop 9 runout 22,000 gpa 45.62.s each loop 9 (x4) maximum flow in . sad.2 pumps on plus 10,000 gpm design flow 12,500 GPM one ' PRR Loop, CS c.e Icop 9 (x2) 20,000 gpa ct normal design  % sign flow Total Flow flow. (in LPCI Mode) 42,000 gpm i

Suppression Pool 0 150*F Long Term ECCS 2 pumps on one 6,500 gpm (x2) 24' 34.51** 2 pumps on 3125 gpm., 27' 31.18'8 pump flows at loop at design 13,000 gpm one loop at- (x2) perJe torus flow design flow 6250 gym temperatures (Containment (177*F) cooling) 4 i ..

18e credit taken for evertressure at. time - O seconds.

2 Use of 2 psig weerpressure.

Actual calculated long term IrFSM avullable at time = 401 seconds.

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REFERENCES

1. TVA letter to NRC, dated July 25, 1997, NRC Bulletin 96-03, Potential Plugging of Emergency Core Cooling Suction Strainers by Debris In Boiling-Water Reactors

2. TVA letter to NRC, dated August 25, 1997, NRC Bulletin 96-03, Potential Plugging of Emergency Core Cooling Suction Strainers by Debris In Boiling-Water Reactors

3. TVA letter to NRC, dated May 24, 1976, Browns Ferry Nuclear Plant Unit 3 - Reportable Deficiency - Potential For RHR pump Operation in Excess of Design Runout

4. Letter to TVA from the United States Atomic Energy Commissiore, dated June 28, 1974, Amendment 3 to The BFN license No. DPR-33 For Browns Ferry Nuclear Plant Unit 1 I

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