ML17352B118: Difference between revisions

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#REDIRECT [[05000250/LER-1995-003, :on 950309,intake Cooling Water Flow Rate Through CCW Heat Exchangers Fell Below Assumed Design Basis. Caused by an Influx of Aquatic Grass & Algae Onto Basket Strainers.Strainers Cleaned]]
| number = ML17352B118
| issue date = 04/07/1995
| title = LER 95-003-00:on 950309,intake Cooling Water Flow Rate Through CCW Heat Exchangers Fell Below Assumed Design Basis. Caused by an Influx of Aquatic Grass & Algae Onto Basket Strainers.Strainers cleaned.W/950407 Ltr
| author name = Knorr J, Plunkett T
| author affiliation = FLORIDA POWER & LIGHT CO.
| addressee name =
| addressee affiliation = NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
| docket = 05000250
| license number =
| contact person =
| document report number = L-95-105, LER-95-003, LER-95-3, NUDOCS 9504180061
| document type = LICENSEE EVENT REPORT (SEE ALSO AO,RO), TEXT-SAFETY REPORT
| page count = 14
}}
 
=Text=
{{#Wiki_filter:m PR.IC)R.IT                    V (ACCELERATED RIDS PROCESSIN REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9504180061                DOC.DATE:    95/04/07    NOTARIZED: NO          DOCKET  N FACIL:50-250 Turkey Point Plant, Unit 3, Florida Power and Light                      C 05000250 AUTH. NAME              AUTHOR AFFILIATION KNORR,J.E.            Florida      Power & Light Co.                                            P PLUNKETT,T.F.          Florida      Power & Light Co.
RECIP.NAME              RECIPIENT AFFILIATION R
 
==SUBJECT:==
LER 95-003-00:on 950309,intake cooling water flow rate through CCW heat exchangers fell below assumed design basis.
Caused by an influx of aquatic grass & algae onto basket strainers.Strainers              cleaned.W/950407    ltr.
DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR                          ENCL  SIZE:
TITLE: 50.73/50.9 Licensee Event Report (LER), Inciden                      Rpt, etc.
NOTES RECIPIENT                COPIES              RECIPIENT        COPIES ID  CODE/NAME              LTTR ENCL          ID  CODE/NAME      LTTR ENCL PD2-2 PD                          1      1    CROTEAU, R  .
1    1.
INTERNAL:      D SPD        B              2      2    AEOD/SPD/RRAB          1    1 I
NRR D C    TE EEL 1
1 1
1 NRR/DE/ECGB NRR/DE/EMEB 1
1 1
1 NRR/DISP/PIPB                    1      1    NRR/DOPS/OECB          1    1 NRR/DRCH/HHFB                    1      1    NRR/DRCH/HICB          1    1 NRR/DRCH/HOLB                    1      1    NRR/DRSS/PRPB          2    2 NRR/DSSA/SPLB                    1      1    NRR/DSSA/SRXB          1    1 RES/DSIR/EIB                      1      1    RGN2    FILE 01      1    1 EXTERNAL: L ST LOBBY WARD                    1      1    LITCO BRYCE,J H        2    2 0
NOAC MURPHY,G.A                  1      1    NOAC POORE,W.          1    1 NRC PDR                          1      1    NUDOCS FULL TXT        1    1 u
N NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE O'ASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOK! P!-37 (EXT. 504-2083 ) TO ELIAtINATEYOUR iAME FROM DISTRIBUTION LISTS I'OR DOCI.'NIEiTS YOU DON"I'EED!
FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR                    27  ENCL      27
 
NpL                                                    APR 0'7 1995 L-95-105 10 CFR 50.73 U. S.      Nuclear Regulatory Commission Attn:        Document  Control Desk Washington, D. C.        20555 Gentlemen:
Re:      Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Reportable Event: 95-003-00 Intake Cooling Water System Flow Rate Found Less Than The    attached Licensee Event Report, 250/95-003-00, is being provided in accordance with 10 CFR 50.73 (a) (2) (ii) (B) .
If  there are any questions, please contact us.
V          ruly yours, T. F. P  un  et Vice President Turkey Point Plant JEK Attachment cc:      Stewart D. Ebneter, Regional Administrator, Region II, USNRC Thomas P. Johnson,    Senior Resident Inspector, USNRC, Turkey Point Plant rwpr~ ~  I
                            ~vcU J  <
9'504i8006i 950407 PDR      ADOCK    05000250 S                      PDR an FPL Group company
 
LICENSEE EVENT REPORT                                                                LER DOCKET NUMBER    2      PAGE  3 FACILITY NAME (1)
TURKEY POINT UNIT 3                                                  05000250                1    '"    ll TITLE (4)            Intake Cooling Water System Flow Rate Found Less Than Required by Desi n Basis EVENT DATE    5          LER NUMBER 6                RPT DATE  7            OTHER FACILITIES INV. 8 MON      DAY        YR                  SE  4    Rf      MON    DAY    YR                  FACILITY NAMES                DOCKET 4  S 03        09        95        95        003        00      04      07      95      Tutkoy Point Unit  4                    05000251 OPERATING MODE 9
1/5 POWER, LEVEL  (10)        60/0 LICENSEE CONTACT FOR THIS LER                12 TELEPHONE NUMBER J. E. Knorr, Regulation Compliance Specialist                                                                          305-246"6757 COMPLETE ONE    LINE  FOR EACH COMPONENT FAILURE DESCRIBED  IN THIS  REPORT    13 COMPNT        MANUFACTURER              NPRDST    CAUSE      SYSTEM        COMP NT      MANUFACTU      NPRDS7 CAUSE RER EXPECTED          MONTH      DAY SUPPLEMENTAL REPORT EXPECTED        (14)    NO              YES  0                            SUBMISSION DATE (15)
(if yoni  ccoploto    EXPECTED SUBMISSION DATE)
ABSTRACT  (16)
At approximately 0435 (EST), on March 9, 1995, the Intake Cooling Water (ICW) flow rate through the Component Cooling Water (CCW) heat exchangers fell below that assumed in the Turkey Point design basis.
The reduced flow rate was due to an influx of aquatic grass and algae onto the basket strainers of the ICW flow path upstream of the CCW heat exchangers. The strainers were cleaned and flow returned to required levels at 0521. The plant was operating at 60 percent reactor influx                                                    power as of a  conservative                measure        due    to  the    potential        for  an    increasing aquatic          grass      and      algae      into    the    ICW    and    circulating          water      systems.
 
LICENSEE EVENT REPORT              (LER) TEXT CONTINUATION FACILITY NAME                        DOCKET NUMBER      LER NUMBER      PAGE NO.
TURKEY POINT UNIT 3                    05000250        95-003"00        20F  11 Z. DESCRIPTION        OF THE EVENT During the evening of March 8, 1995, an influx of aquatic grass mixed with algae occurred at the cooling water intake [NN] from the closed cooling canal [BS:RVR] system at Turkey Point. The cooling water intake is common to the Intake Cooling Water (ICW) system [BS] and the circulating water system [NN]. The ICW system supplies water to the safety related component cooling water (CCW) system and the non-safety related Turbine Plant Cooling Water (TPCW) [TF] system. The ICW, system has three pumps
[BS:P] and two headers [BS] leading to thr'ee CCW heat exchangers
[BS:HX], and two headers leading to two TPCW heat exchangers
[TF:HX], with an in-line basket strainer [BS:STR] for each header. The TPCW headers are automatically isolated upon receipt of a safety injection signal. The circulating water system supplies water to the main condensers [NN:HX]. Early in the evening on March 8, reactor power for Unit 3 was conservatively reduced to 60% to provide operating margin influx were to increase. Unit 4 was in mode 5.
if the grass and algae The outlet of the ICW headers with basket strainers feeds a common header at the inlet of the tube side of three CCW heat exchangers.      For a basket strainer to be mechanically cleaned, the strainer must be isolated. The ICW header containing that strainer is thus declared inoperable. The remaining header (basket strainer) must pass the minimum design flow to maintain operability of the remaining header.
Early in the morning of March 9, the accumulation of aquatic grass and algae on the strainers caused the differential pressure across one ICW strainer to increase, indicating the need for mechanical cleaning. That ICW header was declared inoperable. As a result of the increasing fouling on the opposite ICW header's basket strainer, at approximately 0435 EST, Florida Power & Light Company (FPL) determined that Unit 3 was in a condition that was outside the design basis for ICW flow.
Technical Specification 3.7.3 reads as follows:
      "The Intake Cooling Water System          (ICW)  shall  be OPERABLE with:
: a.      Three  ICW pumps,  and
: b.      Two ICW headers.
MODES 1, 2, 3, and 4.
ZZ'KQH:
a ~ ~  ~  ~
b ~  ~ ~  ~
: c. With only one ICW header OPERABLE, restore two headers to OPERABLE status within 72 hours or be in HOT STANDBY within the next 6 hours and in COLD SHUTDOWN within the following 30 hours."
 
FACILITY NAME t
LICENSEE EVENT REPORT DOCKET NUMBER t
(LER) TEXT CONTINUATXON LER NUMBER  PAGE NO.
TURKEY POINT UNIT 3                  05000250    95-003-00    3 OF 11 Operating Procedure 3/4-0P-019, "Intake Cooling Water System,"
provides guidance on the minimum flow criteria for operability of an ICW header.      The criteria are based on fouling factors and canal temperatures.      In this case, the minimum flow rate for the conditions at the time was approximately 9500 gpm. The flow rate of 9500 gpm ensures that the CCW heat exchangers, with the canal temperature of 75.5 F, are capable of removing the design basis post-accident heat load.
With one of the strainers out of service for mechanical cleaning,
-~- flow through the opposite strainer declined to below the required 9500 gpm as a result of clogging of that strainer. As the aquatic grass and algae continued to flow into the remaining strainer, the ICW flow to the CCW heat exchangers continued to drop to approximately 2500 gpm. At 0435, the second header of ICW was declared inoperable. The action statement in Technical Specification 3.7.3 does not apply to the condition of two inoperable headers. Therefore, the plant entered Technical Specification 3.0.3 which required, within one hour, action to place the unit in Mode 3 within the next 6 hours. At 0521, one basket strainer was cleaned and returned to service, restoring the overall ICW flow rate to greater than 9500 gpm. Therefore, no  plant shutdown    was  required.
II. CAUSE  OF THE EVENT In February and early March 1995, south Florida had little rain.
As a result,    the Turkey Point closed cooling canal water level was reduced. When heavy rain and wind occurred gust prior to the event, the canal levels increased allowing clumps of canal aquatic grass (ruppia mari tima) mixed with algae (batophora) to break loose and flow toward the ICW/circulating water system intake. Under normal grass and algae loading conditions, the aquatic grass and algae are captured by traveling screens at the plant's cooling water intake structure, and washed off of the screens by a screen wash system. In this event, the large amount of suspended grass and algae was enough to cause some of the aquatic material to carry over the traveling screens and into the intake bays for the ICW and circulating water systems. The ICW pumps picked up the carry over material.        The ICW basket strainers, as designed, removed the majority of the grassTheand algae from the flow stream to the CCW heat exchangers.
circulating water pumps also pumped some of the material into the inlet side of the main condenser waterboxes affecting condenser cooling efficiency.
 
t LICENSEE EVENT REPORT t
(LER) TEXT CONTINUATION FACILITY NAME                        DOCKET NUMBER        LER NUMBER    PAGE NO.
TURKEY POINT UNIT 3                    05000250          95-003-00      4 OF 11 IXI . ANALXSES OF THE EVENT The  analysis of this event includes        a  safety assessment  of the following seven areas:
ICW  system functionality CCW  system functionality Containment integrity Equipment qualification Loss of coolant accident (LOCA) Emergency Containment Cooling (ECC) system analysis Main steamline break Radiological consequences Following is a list of some of the key parameters used in the event safety assessment.          They reflect the actual conditions found or design basis assumptions at Turkey Point on the morning of  March 9, 1995.
Containment air temperature = 105 F Outside ambient temperature = 68.5          F Refueling Water Storage Tank (RWST)          fluid temperature  = 75 F (assumed)
ICW  canal  (inlet) temperature    =  75.5'F Offsite    power available 3  Emergency Containment Coolers (ECCs)          available 2  Containment Spray pumps available 2 ICW pumps    in service 2 CCW pumps    in service 2 Residual    Heat Removal  (RHR) pumps    and heat exchangers available Average    CCN  heat exchanger total fouling level at the original design level      (0.00159 hr-ft  F/BTU)
All three CCN heat exchangers        in service Containment pressure = 0.3 psig (assumed)
TPCW isolation upon a safety injection signal {by design)
The    overall function of the ICW system during post-accident conditions is to provide continuous cooling to the CCW heat exchangers.        The ICW system design basis for post-accident operation is a minimum of ICN flow to CCN heat exchangers. A network of closed cooling canals is used as the ultimate heat sink for Turkey Point and provides a continuous supply of cooling water. The limiting safety related ICW flow requirement is based upon the heat load during the mitigation of a design basis large break loss of coolant accident (LBLOCA) .
The configuration of the ICW system at the time of the event was two ICW pumps directing flow to three CCW heat exchangers via one header.      The second header was out of service for strainer cleaning, as discussed above. The ICW system was also delivering
 
1 LICENSEE EVENT REPORT t
(LER) TEXT CONTINUATION FACILITY NAME                    DOCKET NUMBER      LER NUMBER  PAGE NO.
TURKEY POINT UNIT 3                05000250        95-003-00    5 OF 11 flow to the TPCW heat exchangers. The TPCW system is automatically 'solated on a safety injection signal. As a conservatism, for the purposes of this evaluation, credit was not taken for the increased ICW flow through the CCW heat exchangers due to the TPCW isolation.
The controlling parameter on the functionality of the CCW heat exchangers during post-accident conditions at reduced ICW flows is the ICW temperature at the outlet of the CCW heat exchangers.
The reduction in ICW flow through the CCW heat exchanger, given a constant heat removal duty, results in an increase in the ICW outlet temperature of the CCW heat exchanger. The relatively low ICW system inlet temperature      (approximately 75 F compared to 95 F design basis canal temperature) at the time of the event, reduced the potential maximum for the post accident ICW temperature at the outlet of the CCW heat exchangers.
As discussed below, a detailed thermal analysis of the design basis LBLOCA event was analyzed assuming that the event occurred concurrent with the ICW low flow event. To support the LBLOCA thermal analysis, a time averaged ICW flow to the CCW heat exchangers was established for the ICW low flow event. The following flow profile was used, representative of the plant conditions observed:
0-10 minutes,  9000 gpm 11 minutes, step change to 5000 gpm 11-40 minutes, gradual reduction to 2500        gpm 40-56 minutes, 2500 gpm 57 minutes, step change to 9500 gpm 57-60 minutes, 9500 gpm Using the above    profile a time averaged ICW flow of approximately 4675 gpm (1560 gpm per CCW heat exchanger) was used in the analysis for the first hour and 9500 gpm thereafter. This is a conservative assumption since the ICW flow rates returned to levels greater than 9500 gpm after the a basket strainer was mechanically cleaned. This time averaged ICW flow was used to provide a more realistic set of input parameters for the LBLOCA thermal analysis. The analysis model used conservative assumptions for overall heat transfer.
Based upon the time averaged flow conditions, the peak ICW temperature was calculated to occur shortly after the beginning of an assumed LBLOCA following the start of the emergency containment coolers (ECCs) . The maximum calculated CCW heat exchanger ICW outlet temperature is approximately 134 F. The temperature steadily declines to less than 100 F after about 45 minutes. Following switchover to cold leg recirculation (after placing the RHR heat exchangers in service), the ICW temperature increases to approximately 124 F, again decreasing steadily after reaching that temperature.
, FPL performed an assessment      of the temperature affects on the structural integrity of the ICW system and has concluded that'he ICW system would remain functional.        Therefore, the ICW system
 
t LICENSEE EVENT REPORT t
(LER) TEXT CONTINUATION FACILITY NAME                    DOCKET NUMBER    LER NUMBER    PAGE NO.
TURKEY POINT UNIT 3                05000250      95-003-00      6 OF 11 would have continued to perform      its safety function of  continuing to cool the CCW heat exch~ngers.
The  overall function of the CCW system during post-accident conditions is to provide a continuous cooling of safety related components. This requires that the CCW return header temperature remain within the design basis of the system and that the supply temperature remain within equipment operating limits.
At Turkey Point, essential components served by the CCW system are the RHR pumps, Safety Injection (SI) pumps, Containment Spray (CS) pumps, ECCs and RHR heat exchangers.      In addition a Chemical and Volume Control System (CVCS) positive displacement (charging) pump is used post-accident to adjust containment sump pH and is also served by CCW.
The following are the CCW system temperatures of interest:
CCW shell side outlet (" supply" ) temperature ECC CCW  outlet temperature RHR heat  exchanger CCW outlet temperature CCW shell side inlet ("return") temperature The post accident operability limit for CCW "supply" is 150 F.
The temperature has been modeled to remain at 150 F for four hours and then to decrease at a minimum of 1 F/hr for the next 30 hours to 120 F, remaining at that level for the remainder of the LBLOCA. The SI pump oil cooler is controlling for this temperature profile. The analysis shows that the SI pump remains operable.
For the  ECCs and RHR  heat exchangers, the analysis verified that the CCW "supply" temperature remained below the system design temperature for those systems. The limit on the "supply" temperature is required to ensure maintenance of single phase flow through the systems.
For the CCW heat exchanger "return, " the limiting temperature is dictated by the net positive suction head of the CCW pump. A temperature as high as 172.7 F has been evaluated as acceptable for the CCW pump suction. This calculation ensured single phase flow at the suction of the CCW pumps.
An assessment    of the overall CCW heat removal capability was made based upon the operating conditions at the time of the ICW low flow event. The design basis post-accident CCW heat exchanger heat load used to verify the thermal performance of the CCW heat exchangers is approximately 60 million BTU/hr per heat exchanger.
With two heat exchangers (design basis) available the total heat removal capability of the CCW system is 120 million BTU/hr.
 
t LICENSEE EVENT REPORT t
(LER) TEXT CONTINUATION FACILITY NAME                    DOCKET NUMBER      LER NUMBER PAGE NO.
TURKEY POINT UNIT 3                05000250        95-003-00  7 OF 11 At the lower    ICW  flow and lower ICW inlet temperature present on March 9, with an allowance for the CCW "supply" temperature to rise to 150 F and three CCW heat exchangers available, the total heat removal capability of the CCW system is estimated to be approximately 123 million BTU/hr. This assessment indicates that the reduced ICW flow to the CCW heat exchangers would not have caused the CCW system "supply" temperature to be significantly higher than the limit of 150 F. If CCW system thermal inertia and heat up times were considered, the actual CCW "supply" temperature rise would have been less than calculated above.
A detailed analysis of the ICW low flow event limiting system flows and maximum heat loads (e.g., three ECCs) was also completed. The analysis assumed two CCW pumps and three CCW heat exchangers with the fouling factors experienced when the ICW low flow event occurred. As mentioned before, the time averaged ICW flow rate of approximately 4675 gpm was used for the first 60 minutes and 9500 gpm for the remainder of the analysis. Credit was taken for operation of all essential safeguards equipment and actual plant operating conditions at the time of the ICW low flow. In general, the actual plant operating conditions at the time of the event were much less limiting that those assumed in the safety analysis. The conditions present at the time of the event provided a benefit that compensated for the lower than normal ICW flow. However the assumption of 3 ECCs in service is more limiting from a CCW system heat removal perspective.
The peak CCW "return" temperature was calculated to reach approximately 170 F, decreasing to about 105 F within 45 minutes.
Following switchover to cold leg recirculation, a second peak of approximately 155 F was calculated to occur.
For the CCW "supply" temperature, a peak of 156 F was calculated decreasing to'150'F within about a minute. Over the next 45 minutes the temperature would drop to about 100 F. After switchover to cold leg recirculation, the temperature would again increase to about 141 F. Although the maximum calculated temperature slightly exceeded the previously established limit (156'F versus 150 F), the duration of the higher temperature condition (less than a minute) was much less than previously considered. Over the short time frame, the thermal lag of the system combined with thermal inertia would have limited the temperature rise to less than 150'F.        In all cases the temperatures steadily decline as ICW flow is restored after a basket strainer    is cleaned.
Although the specific detailed thermal analysis results are clearly conservative in nature to the use of steady-state instantaneous heat transfer assumptions, the results are consistent with the overall heat removal assessment noted earlier. Considering the dynamic nature of the CCW heat removal process,  the analyses show that the CCW temperature would have remained within the component allowable temperatures and the CCW system would not have been adversely affected by the ICW low flow event.
 
t LICENSEE EVENT REPORT t
(LER) TEXT CONTINUATION PAGE NO.
FACILITY NAME                        DOCKET NUMBER        LER NUMBER TURKEY. POINT UNIT 3                    05000250          95-003-00          8 OF 11 In addition, FPL performed a preliminary assessment of temperature conditions which bound the above analyses and concludes, considering thermal stress effects, the CCW system would remain functional. Therefore, the overall functionality of the CCW system with respect to its primary safety function would not have been affected by this event.
The impact    of this    ICW  low flow condition was evaluated for containment pressure        response with respect to LBLOCA and Main Steamline Break (MSLB) inside containment. The plant conditions and configuration at the time of the ICW low flow event are less limiting than the current design basis LOCA containment transient. The current limiting transient is the containment response to the double-ended pump suction (DEPS) break with a concurrent loss of off-site power and the failure of an emergency diesel generator. The current peak containment initial          pressure for this transient    is  49.9  psig  which  occurs  during    the            blowdown is 55 period. The  containment    design  pressure    for  Turkey    Point psig. Recently    revised  calculations    of  mass  and  energy  releases provided additional conservatism in the initial core stored energy, decay heat level, initial internal RCS energy, and safety injection enthalpy over the current plant conditions.
In the analysis, the containment response to the DEPS break was terminated at 5 hours. Modeling the low ICW flow transient for 4 hours after regaining the required ICW flow of 9500 gpm ensured the data recovery for containment response from the blowdown period through cold leg recirculation. This analysis showed                      a peak containment pressure of 45.2 psig at approximately 19.4 seconds after initiation of the DEPS. Although not part of the design basis for Turkey Point, NRC Standard Review Plan criteria for pressure reduction after an event isavailable    50% of the peak pressure within 24 hours. Due to the          amount    of                heat removal equipment, the containment        pressure  met  the  criteria    within approximately    30  minutes  and  is  near  25%  of  peak  pressure  within 5 hours.
Using recently revised calculations, the limiting MSLB containment peak pressure is 42.8 psig. This is based upon a transient beginning at zero power with a failure        ft'. of a main steam all check valve (MSCV) and a break area of 1.4                      With secondary safety systems assumed operable              and  no  single  active failures, the mass and energy          releases    from  the  broken  steam    line would be significantly less        when  compared    to  the  limiting transient. Peak containment pressures which result from                    a MSLB transient with no system        failures  typically    are  less  than  30 psigo Based upon the above results, the current design basis DEPS break containment response with the failure of a diesel generator and concurrent loss of offsite power, and the 1.4 ft MSLB at flow              zero power  with  a MSCV  failure,  remain  bounding.      The  low ICW event would not have caused a more limiting condition than that which is already analyzed for containment integrity.
 
TURKEY POINT UNIT 3 t
LICENSEE EVENT REPORT FACILITY NAME                    DOCKET NUMBER 05000250 l
(LER) TEXT CONTINUATION LER NUMBER 95-003-00 PAGE NO.
9 OF 11 From  the containment integrity analyses above, the calculated limiting peak    containment temperature ~as determined to be 268.4 F at 19.4 seconds into the event. The analyses indicate that, assuming a low ICW flow event, containment temperatures are maintained well below the envi.ronmental qualification (EQ) envelope at all times. At 5 hours aftex a LOCA event, the containment temperature will be approximately 197 F. Also, from the containment integxity analyses, the peak containment pressure reached was 45.2 psig at 19.4 seconds and fell to 13.5 psig within 5.hours. Therefore, the calculated containment temperatures and pressure levels due to the low ICW flow event did not exceed the EQ allowables.
This analysis is not affected by the low ICW flow event in a non-conservative manner. Elevated CCW system "supply" temperatures to the ECCs are a benefit to the 'containment pressure affects on the LOCA peak clad temperature (PCT) calculations. The minimum backpressures assumed in PCT calculations are conservative since the elevated CCW temperatures to the ECCs would reduce the ECCs performance and therefore increase backpressures.
See above    for a discussion of the affect of the event    on containment    integrity.
The MSLB analysis is not    affected by the ICW low flow event  as long as the SI pumps and    all other safety systems remain operable.
The design basis doses are not affected by the ICW low flow event. As stated earlier, the design basis containment integrity analyses remain bounding, the LOCA PCT analyses are not affected, the MSLB analyses are not affected and the safety system components remain operable and intact. Therefore, doses to plant personnel and the general public are not affected.
The  overall conclusions of the above safety assessments are that all critical    areas of plant accident analyses remain bounded.
This conclusion is possible because of the short duration of the low flow transient and actual plant operating conditions at the time of the event are well below limiting analyses conditions.
The inherent margin provided by the plant configuration and the lower operating conditions countered the adverse affects associated with the temporary low ICW flow.
 
t LICENSEE EVENT REPORT t
(LER) TEXT CONTINUATION FACILITY NAME                      DOCKET NUMBER    LER NUMBER  PAGE No.
TURKEY, POINT UNIT 3                05000250      95-003-00    10 OF 11 Additionally,    FPL performed a probablistic safety assessment    for this event.      The low ICW flow was conservatively modeled as a complete loss of CCW flow for one hour. The assessment concluded that the calculated core damage frequency did not increase above the base line of 6.63x10 '/year.
ZV. CORRECTIVE ACTIONS The  basket strainers were mechanically cleaned to restore ICW  flow to greater than the minimum flow required for the canal temperature and CCW heat exchanger fouling factors found at the time of the event.
: 2. Two  floating  booms  are installed in the canal system. The first, installed prior    to the event, is at the extreme southern end of the canal system to catch floating aquatic grass and algae material prior to the flow release point into the return canals. This first boom was only partially effective in controlling the grass and algae influx. The second was installed in the final return canal within a quarter mile of the intakes to catch any floating material which was not caught by the first floating boom. These booms are used on an as needed basis.
: 3. A pump has been installed to remove the grass and algae from the canal at the location of the first boom installed at the southern end of the canal system. This pump is used on an as needed basis.
4 ~  An Off Normal Operating Procedure, 3/4 ONOP-011, "Screen Wash System/Intake Malfunction," has been developed (March 28, 1995) to provide guidance on actions to be taken in the event of a major influx of grass/debris into the intake structure. This procedure also references 3/4-0NOP-019, "Intake Cooling Water Malfunction."
: 5. Training brief g544, which clarifies the need to run ICW pumps in bays without circulating pumps operating to reduce the level of basket strainer fouling, has been issued.
: 6. A traveling screen performance program will be developed to monitor and improve the performance of the screen system.
Areas to be considered, and included        if appropriate, are screen wash nozzle performance, screen wash pump performance, screen wash strainer performance, and traveling screen hole size. The program will be evaluated and implemented by July 15, 1995.
: 7. The ICW/CCW basket strainer performance can be improved. A method for determining flow through each basket strainer will be evaluated and implemented as appropriate. The evaluation and recommendation of corrective actions will be completed by July 1, 1995. Any recommended system modifications will be scheduled for refueling outages starting after    1996.
 
LICENSEE EVENT REPORT      (LER) TEXT CONTINUATION FACILITY NAME                DOCKET NUMBER      LER NUMBER  PAGE NO.
TURKEY POINT UNIT 3            05000250        95-003"00    11 OF 11 V. ADDITIONAL INFORMATION EIIS Codes are shown in the format [EIIS    SYSTEM: IEEE component function identifier,  second component  function identifier (if appropriate)].
No  similar Licensee Event Reports have been submitted concerning low ICN flow.}}

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