ML20247M100
| ML20247M100 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/26/1989 |
| From: | Donohew J Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8906020359 | |
| Download: ML20247M100 (32) | |
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. [p'we' 9,, UNITED STATES E o NUCLEAR REGULATORY COMMISSION 3 I wAsHmeTow, p. c.acess
- ) May 26, 1989 u .....
Docket Nos. 50-327 and 50-328 LICENSEE: Tennessee Valley Authority FACILITIES:' Sequoyah Nuclear Plant,-Units 1 and 2 l
SUBJECT:
MINUTES OF THE MAY 11, 1989 MEETING WITH THE TENNESSEE VALLEY AUTHORITY (TVA) ON APPENDIX K ANALYSES FOR SEQUOYAH On Thursday, May 11, 1989, a meeting was held at NRC headquarters, in Rockville, Maryland, between the TVA Projects Division and the Tennessee Valley
. Authority (TVA). The meeting was held at the request of TVA to discuss the performance of best estimate calculations, in accordance with Appendix K.of 10 CFR Part 50, for Sequoyah Nuclear Plant, Units 1 and 2. Enclosure 1 is a list of individuals attending the meeting. The following is.a suanary of the significant items discussed and the actions taken or proposed.
TVA provided a handout, which is Enclosure 2. The agenda for the meeting is Page.1 of Enclosure 2. TVA stated that the purpose of the meeting was to:
(1) discuss the overall strategy of TVA submitting loss-of-coolant (LOCA) analyses to meet 10 CFR 50.46 for Sequoyah, (2). discuss the LOCA analyses needed to meet the exemptions granted Sequoyah on January 26,1989, and (3) discuss the schedule to submit "best estimate" LOCA analyses for Sequoyah.
The e."Aptions granted January 26, 1989, for Sequoyah, Units 1 and 2 require TVA to submit LOCA analyses for plant operation for each unit without upper head injection (UHI) before the restart of the unit from its Cycle 4 refueling outage. The UHI.. system. is being removed from each unit .in its Cycle 4 refueling outage, both scheduled for 1990. The "best estimate" LOCA analysis is defined in Appendix K to 10 CFR Part 50.
The proposed plan for LOCA analyses for Sequoyah by TVA is given on page 4 of the handout in Enclosure 2. TVA requested that the staff agree with this plan.
The milestones are on page 5 of Enclosure 2. The overall strategy of the plan is given on page 6 of Enclosure 2.
The interim LOCA analyses for Sequoyah to meet the exemptions granted on
. January 26, 1989 are discussed on pages 7-15 of Enclosure 2. The "best estimate" LOCA analyses for Sequouah are discussed on pages 16-26 of Enclosure 2.
TVA concluded its presentation by stating that the "best estimate" approach
. will: (1) provide more realistic calculations, (2) re uncertainties which were never part of Appendix K, {3) providequire qualification of a "true" 8906020359 890526
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indicationofplantmarginofsafetyand(4)reduceNRCrevieweffortinthe future.-
The staff discussed TVA's proposed plan for performing LOCA analyses on' Sequoyah. This is page 4 of Enclosure 2. The staff concluded that the' plan was acceptable. This ended the meeting.
q TD LM A Jac N. Dono$ p, Jr., Project Manager TVA Projects Division .i Office of Nuclear Reactor Regulation -
Enclosures:
- 1. Attendance List
- 2. TVA's Meeting Handout L
cc w/ enclosure:
- See next page l
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DISTRIBUTION FOR MEETING
SUMMARY
DATED: May 26, 1989 !
I Facilty: Sequoyah Nuclear Ple.nt, Units 1 and 2 -l l
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- ~flPC PCR Local.PCR Projects Reading ADSP Reading J. Sniezek D. Crutchfield B. D. Liaw S. Black R. Pierson J. Donohew T. Quay M. Sims B. Wilson J. Brady..
E. Marinos- ;
E. Goodwin 0GC B. Bordenick ACRS(10)
GPA/CA E. Jordan.
B. Grimes P. Gwynn J. Scarborough G. Marcus L. Norrholm C. Ader J. Gray R. Borchardt SQN Rdg. file
- cc: Licensee / Applicant & Service List i - - _ --_L
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' General' Counsel Mr. Kenneth.M. Jenison Senior Resident Inspector Tennessee Valley Authority 400 West Sumit Hill Drive Sequoyah Nuclear. Plant E11 B33 '
U.S. Nuclear' Regulatory Comission Knoxvill .e, Tennessee. 37902 2600 Igou Ferry Road Soddy Daisy.. Tennessee 37379 "
Mr. F. L. Moreadith Vice' President,. Nuclear Engineering Mr. Michael H.~Mobley, Director Tennessee Valley Authority Division of Radiological Health
' 400 West Sumit Hill Drive T.E.R.R.A. Building, 6th Floor-W12'A12 150 9th Avenue North
' Knoxville, Tennessee 37902 Nashville, Tennessee. 37219-5404 Dr. Henry Myers, Science Advisor-Vice President and Nuclear Comittee on Interior Technical Director and Insular Affairs
. Tennessee. Valley Authority U.S. House of Representatives-
-SN 1578 Lookout Place Washington, D.C. 20515 Chattanooga, Tennessee 37402-2801 Tennessee Valley Authority Mr'. M. J. Ray', Acting Director Rockville Office Nuclear Safety and Licensing 11921 Rockville Pike ;
Tennessee Valley Authority Suite 402 i SN 1578 Lookout-Place Rockville, Maryland 20852 Chattanooga, Tennessee 37402-2801 Mr.-John L. LaPoint Site Director
.Sequoyah Nuclear Plant Tennessee Valley Authority l P..O. Box 2000 Soddy Daisy, Tennessee 37379 Mr. M. Burzynski Acting. Site Licensing Manager Sequoyah Nuclear Plant P. O. Box 2000 Soddy Daisy, Tennessee 37379 County Judge
. Hamilton County Courthouse Chattanooga, Tennessee 37402 Regional Administrator, Region II U.S. Nuclear Regulatory Comission l 101 Marietta Street, N.W.
Atlanta, Georgia 30323
_____________________-_1
ENCLOSURE 1 LIST OF ATTENDEES MAY 11 , 1989 MEETING ON LOCA ANALYSES Name Affiliation
- J. Donohew NRC/TVA R. Pierson NRC/TVA E. Marinos NRC/TVA W. Hodges. NRC !
- 7. Rotella NRC/TVA S. Black NRC/TVA i Y. G. Hsii NRC M. Burzynski TVA R. Bryan TVA T. Lordi W L. Tomasic W N. Farukhi W L. Hochreiter W !
M. Garrett W i
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- Affiliation TVA - Tennessee Valley Authority NRC/TVA - Nuclear Regulatory Connission, TVA Projects Division W - Westinghouse Electric Corporation i
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,,- 9 ENCLOSURE 2 NUCLEAR REGULATORY COMISSION, TENNESSEE VALLEY AUTHORITY, !
WESTINGHOUSE ELECTRIC CORPORATION MEETING TO DISCUSS LOCA ANALYSES STRATEGY FOR SEQUOYAH UNITS 1 & 2
(
MAY 11, 1989 1
0 OVERALL STRATEGY I O INTERIM LOCA ANALYSIS FOR SEQUOYAH 0 BEST ESTIMATE LOCA ANALYSIS 4
4
BACKGROUND Pl#TCMGESTOUHISYSTEMRESULIEDINCHANGESTOIHELOCAANALYSIS SENSITIVITYSTUDIESANDPEAKINGFACIORREDUCTIONSUSED10JUSTIFYCNGES IfMORARYEXFMTIONTO10CFR50.46 GRANTED
' TVACOMMITMENTTOPROVIDEANALYSISTODEMONSTRATECOMPLIANCEWITH 100FR50.46BYSTARTUPFROMTHECYCLE4RFOs i
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BESTESTIMATEBENEFITS ALLOWSUSEOFENHANCEDFUELDESIGNS
-REDUCEDVESSELFLUENCEWITHLOWLEAKAGELOADINGPATTERNS
-REDUCEDRADIATIONEXPOSURE
-REDUCEDCOST,FREEINGRESOURCESFORALTERNATIVEUSES
' ADDITIONALOPERATINGMARGINFLEXIBILI1Y i
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PROPOSEDPLAN PERFORM NON-LOCA ANALYSES FOR UHI REMOVAL FOR CYCLE 4 RF0 4
PERFORMSBLOCAANALYSESUSINGNOIRUMPFORCYCLE4RF0 PERFORMLIMITINGLBLOCAANALYSISUSINGBASHFORCYCLE4RF0 l
RESTARTSQNUNIISAFTERCYCLE4RFOsWITHUHIREMOVEDFROMSERVICE DEVELOPBESTESTIMATEANALYSISFORSQNONTVA/NRCAGREEDSCHEDU NOTE: U104RF0 STARTS 4/90 U204RF0 STARTS 10/90 UIC5RF0 STARTS 10/91 U205RF0 STARTS 4/92 RF6 = nq{ M ou w3e_
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"; j PROPOSEDMILESTONES l TVA/NRCAGREEMENTONBESTESTIMAIEANALYSISPLANANDSCHEDULE l
- BEGINDEVELOPMENTOFSQNBESTESTIMAIEANALYSIS-OCTOBER 1989 J i
SUBMITTAL 0FSQNANALYSESANDTECHNICALSPECIFICATIONCHANGESFOi
. REFUELING OUTAGE (RF0)- Womb \W SUBMITTAL 0FSQNBESTESTIMATEANALYSISREPORTANDTECHNICALSPEC CHANGES-NOVEMBER 1990 NR0 APPROVAL 0FBESTESTIMATEANALYSIS-AUGUST 1991 l
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o' OVERALL STRATEGY o TVA TO VALVE OUT UHI ON SEQUOYAH UNITS AND NOT CHANGE COLD LEG ACCUMULATOR LINE o BASED.ON WATTS BAR BASH ANALYSIS, W TO PERFORM WORST BREAK ANALYSIS FOR SEQUOYAH UNITS WITH UHI OUT, NO ACCUMULATOR LINE CHANGE, HIGHER ACCUMULATOR PRESSURE !
ANTICIPATED ALLOWABLE FQ=2.28 (CURRENT ALLOWABLE FQ=2.15) o W WITH TVA, TO INITIATE BEST ESTIMATE LOCA ANALYSIS WITH WCOBRA/ TRAC TO COMPLY WITH NEW APPENDIX K RULE CHANGE REGAIN FQ MARGIN FOR SEQUOYAH l
PROVIDE ADDITIONAL LOCA MARGIN FOR l UNITS l
0506H:LEN/050989 2
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INTERIM LOCA ANALYSIS FOR SEQUOYAH I
MAY 11, 1989 j O PROPOSED APPROACH I 0
l LIMITING BREAK DETERMINATION O PLANT CONFIGURATION
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j 0 PREVIOUS BASH ANALYSES l 0 CONCLUSIONS 1
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.# 4 INTERIM LOCA ANALYSIS FOR SEQUOYAH PROPOSED APPROACH 0 DO NOT MODIFY ACCUMULATOR DELIVERY LINES 0 PERFORM SMALL BREAK LOCA ANALYSES 4 i
- USE APPROVED NOTRUMP SMALL BREAK LOCA ANALYSIS l METHODOLOGY !
- INCORPORATE BEST ESTIMATE PARAMETERS o FQT = 2.50 o FoH = 1.62 - 1.70 l o SGTP = 10 %
0 PERFORM INTERIM LARGE BREAK LOCA ANALYSES
- USE APPROVED BASH LARGE BREAK LOCA ANALYSIS METHODOLOGY
- PERFORM ANALYSIS OF THE LIMITING DISCHARGE COEFFICIENT DECLG BREAK
- LIMITING DISCHARGE COEFFICIENT BASED UPON WESTINGHOUSE BASH EXPERIENCE AND PREVIOUS ANALYSES PERFORMED TO SUPPORT UHI SYSTEM REMOVAL 1
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INTERIM LOCA ANALYSIS FOR SEQUOYAH LIMITING BREAK DETERMINATION 0 BLOWDOWN RESPONSE
- CORE STORED ENERGY
- BREAK CONFIGURATION
- RCS/ VESSEL. CONFIGURATION i
- RCS TEMPERATURES O REFLOOD RESPONSE
- SAFETY INJECTION SYSTEM
- SYSTEM RESISTANCE
- CONTAINMENT DESIGN
- FUEL DESIGN l
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INTERIM LOCA ANALYSIS FOR SEQUOYAH i
PLANT CONFIGURATION UHI UPPER INTERNALS SEQUOYAH WATTS BAR (417-IDTCU) (417-IDNFU) i CORE POWER LEVEL 3411 MWT 3411 MWT '
FUEL DESIGN 17x17 17X17 FQT 2.25 - 2.28 2.40 FoH- 1.55 1.58 UPPER HEAD TEMPERATURE T-COLD T-COLD ,
UPPER SUPPORT PLATE INV. TOP HAT INV. TOP HAT LOWER SUPPORT PLATE CURVED FLAT TS/NP THERMALShlD NEUTRON PADS BARREL BAFFLE DOWNFLOW UPFLOW (CONV)-
PRESSURIZER VOLUME 1800 cU.FT 1800 CU.FT SG TYPE 51 D3 SG DESIGN PRESSURE 1100 1200 RCP TYPE 93A 93A CONTAINMENT DESIGN ICE-COND. ICE-COND.
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INTERIM.LOCA ANALYSIS FOR SEQUOYAH PLANT CONFIGURATION UHI UPPER INTERNALS j 417-IDNFU 417-IUNFU l CORE POWER LEVEL 3411 MWT 3411 MWT FUEL DESIGN 17x17 17X17 1 FQT 2.32 2.32 FoH 1.55 1.55 l UPPER HEAD TEMPERATURE T-COLD T-COLD '
UPPER SUPPORT PLATE INV. TOP HAT INV. TOP HAT LOWER SUPPORT PLATE FLAT FLAT BARREL BAFFLE DOWNFLOW UPFLOW (CONV)
TS/NP NEUTRON PADS NEUTRON PADS PRESSURIZER VOLUME 1800 CU.FT 1800 CU.FT SG TYPE D2/D3 D3/D5
~SG DESIGN PRESSURE 1200 1200 RCP TYPE 93A 93A CONTAINMENT DESIGN ICE-COND. ICE-COND.
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INTERIM LOCA ANALYSIS FOR SEQUOYAH l UHI ELIMINATION l PREVIOUS ANALYSIS EXPERIENCE l PLANT BREAK BASH PCT l l
417-IDNFU 0.4 1614 0.6 1841 0.8 1795 0.6 MAX-SI 1803 i 417-IUNFU 0.6 1681 0.8 1704 1.0 1667 0.8 MAX-SI 1698 417-IDNFU 0.4 2161 (WATTS BAR) 0.6 2173 0.8 2143 0.6 MAX-SI 2193 (UPFLOW BB) 0.6 2126 (UPFLOW BB) 0.6 MAX-SI 2125 4
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T E E A T T E E N R A A M R G L E L L U U I E P P P L S S V M ' O S E E E i E T V E D L T R L R R N O F O R P T R G D P F P E N E I A P A P Z N E WS E U B U I G E M O E H S S R E I P N P D L U P S Y I R R E P R S Y E T A E L E E R N E S T D T R E T H P P R / W E P N O U Q d P P A S O 3 G G C O C F F F U U B T L P S S R C
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INTERIM LOCA ANALYSIS F0P. SEQUOYAH PREVIOUS ANALYSIS EXPERIENCE NON-UHI UPPER INTERNALS PLANT BREAK BASH PCT 417-TUNF 0.4 1517 REDUCED TH0T 0.6 1754 " "
0.8 1629 " "
0.6 1871 NOMINAL TH0T 0.6 MAX-SI 1816 417-FUNF 0.4 1892 0.6 1983 0.8 1879 0.6 MAX-SI 1915 L: 417-IUNF 0.4 1801 0.6 2014 0.8 1776 0.6 MAX-SI 1929 417-TDTC 0.4 2091 0.6 2071 0.8 1911 0.4 MAX-SI 2017 1
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INTERIM LOCA ANALYSIS FOR SEQUOYAH CONCLUSIONS 0 UHI SYSTEM WILL BE REMOVED FROM SERVICE PRIOR TO ;
STARTUP AND OPERATION OF CYCLE 5 FOR SEQUOYAH ;
UNITS 1 & 2 0 ANALYSES WILL BE PERFORMED WITH NRC APPROVED ECCS EVALUATION MODEL METHODOLOGIES TO SUPPORT CYCLE 5 STARTUP AND OPERATION 0 SMALL BREAK ANALYSES WILL BE PERFORMED WITH NOTRUMP TO SUPPORT BEST ESTIMATE LOCA ANALYSIS PARAMETERS 0 LARGE BREAK ANALYS.IS WILL BE PERFORMED WITH BASH FOR THE LIMITING BREAK 1
0 LIMITING BREAK IS 0.6 DECLG BASED UPON PREVIOUS EXPERIENCE AND ENGINEERING EVALUATION lW u
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-l WCOBRA/ TRAC BEST ESTIMATE LOCA FOR TVA SEQUOYAH UNITS i
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l 0506H:LEM/050989-3
o W BEST ESTIMATE STRATEGY HAS FOLLOWING ELEMENTS APPENDIX K RULE CHANGE' REQUIREMENTS FOR BEST ESTIMATE THERMAL / HYDRAULIC METHODS NRC APPROVAL OF WCOBRA/ TRAC UNDER SECY-83-472 FOR TWO-LOOP PWR'S W/EPRI PROGRAM ON BEST ESTIMATE CODE UNCERTAINTIES TO ADDRESS NEW APPENDIX K RULE CHANGE 4
0506H:LEM/050989 4
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0 APPENDIX K RULE CHANGES o THE NEW APPENDIX K RULE WAS ISSUED 9/16/88 TO BE EFFECTIVE ON 10/17/88. THE KEY FEATURES OF THE NEW RULE AS WE UNDERSTAND THEM ARE:
NO SPECIFIC MODELS/ CORRELATIONS, APPLICANT MUST DEVELOP MODELS, BASED ON RESEARCH DATA, -
WHICH ARE REALISTIC AND CAN PREDICT DATA CODE MUST BE A REALISTIC REPRESENTATION OF THE LOCA PROCESS. CODES WHICH CONTAIN UNREALISTIC OR OVERSIMPLIFIED MODELS, TO BE CONSERVATIVE, WILL NOT BE ACCEPTED. LARGE H EMPHASIS ON CODE PREDICTIONS OF INTEGRAL DATA.
RULE REQUIRES CALCULATION OF NORMAL, 50TH PERCENTILE PCT, AND AN ACCURATE ESTIMATE OF THE 95TH PERCENTILE PCT TAKING INTO ACCOUNT THE UNCERTAINTY IN THE PLANT, THE ACCIDENT CONDITIONS, AND THE COMPUTER CODE.
CURRENT EM MODELS ARE STILL PERMITTED.
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p DEVELOPMENT OF WCOBRA/ TRAC 1
.1 o INITIALLY DEVELOPED FOR THE USNRC AT PACIFIC NORTHWEST LABORATORY UNDER THE NAME OF COBRA / TRAC o COBRA / TRAC IS COMBINATION OF i COBRA-TF TWO-FLUID, THREE' FIELD VESSEL MODEL J l
TRAC-PD2, FIVE EQUATION DRIFT FLUX LOOP MODEL o COBRA /TF WAS USED AS PART OF W/NRC/EPRI FLECHT-SEASET FLOW BLOCKAGE PROGRAM o W HAS CONTINUED TO MAKE SEVERAL CODE IMPROVEMENTS TO COBRA / TRAC RESULTING IN WCOBRA/ TRAC o WCOBRA/ TRAC HAS BEEN ASSESSED AGAINST FLECHT-SEASET - LOFT NRU - ORNL CCTF - G-2 UPTF - CREARE TESTS o NRC APPROVED WCOBRA/ TRAC FOR TWO-LOOP W PLANTS WITH UPI (8/29/88) UNDER SECY-83-472 0506M:LEH/050989 6 I4
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., DEVELOPMENT OF WCOBRA/ TRAC (CONT'D) o W. PLANS TO LICENSE WCOBRA/ TRAC.UNDER THE NEW APPENDIX K RULE FOR ALL PWR TYPES o THE NEW RULE APPENDIX K VERSION OF WCOBRA/ TRAC WILL HAVE MODEL IMPROVEMENTS OVER THE SECY-83-472 VERSION OF THE CODE SPACER GRID MODEL HEAT TRANSFER MODELS SIMILAR TO THOSE APPROVED FOR BART AND USED IN COBRA /TF (FLECHT-SEASET) WILL BE INCORPORATED SMALL IMPROVEMENTS IN FILM BOILING MODEL SIMILAR TO COBRA /TF SMALL IMPROVEMENTS IN KINETICS MODEL SMALL IMPROVEMENTS IN THE ACCUMULATOR NITROGEN MODEL ADDITION OF TRAC-PF1 CRITICAL FLOW MODEL o THESE MODELS WILL BE DESCRIBED IN THE WCOBRA/ TRAC MODELS AND CORRELATIONS DOCUMENT 0506H:LEN/050989 7 h lj
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o CURRENT-EPRI/ WESTINGHOUSE BEST ESTIMATE PROGRAM W/EPRI HAVE A JOINT PROGRAM TO INVESTIGATE SCALING EFFECTS FOR BEST ESTIMATE CODES W/EPRI HAVE A JOINT PROGRAM TO DEVELOP THE BEST ESTIMATE CODE UNCERTAINTY APPROACH FOR THE NEW APPENDIX K RULE. KEY FEATURES:
TO DEVELOP A METHODOLOGY TO ESTABLISH THE UNCERTAINTY IN THE REACTOR PCT CALCULATION IN COMPLIANCE WITH THE NEW RULE CHANGE LICENSE THE METHODOLOGY WITH THE NRC USING A HOST UTILITY'S DOCKET TO IDENTIFY LOCA MARGIN DEMONSTRATE HOW THE IDENTIFIED LOCA MARGIN CAN BE UTILIZED TO IMPROVE PWR PERFORMANCE W/ VIRGINIA POWER HAVE A JOINT PROGRAM TO APPLY THE BEST ESTIMATE CODE AND UNCERTAINTY APPROACH ON NORTH ANNA PLANT (3-LOOP)
W/TVA ARE PROPOSING A SIMILAR PROGRAM TO APPLY THE BEST ESTIMATE CODE AND UNCERTAINTY I TO THE SEQUOYAH UNITS ;
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ELEMENTS OF THE EPRI/W PROGRAM ON CODE UNCERTAINTY TASK 1 LOCA TRANSIENT REVIEW o FIND IMPORTANT LOCA PROCESSES o RANK PROCESSES TASK 2 UNCERTAINTIES IN CODE DEVELOPMENT PHASE o COMPLETENESS OF EQUATIONS o WILL'THE CODE /MODELS CAPTURE THE PHENOMENA TASK 3 UNCERTAINTIES IN CODE VERIFICATION PHASE o COMPARE CODE TO DATA TO SIMULATE LOCA PHENOMENA o QUANTIFY CODE UNCERTAINTY AGAINST DATA TASK 4 UNCERTAINTIES IN CODE APPLICATION PHASE o MODELING OF PWR GE0 METRY, B0UNDARY CONDITIONS, ACCIDENT CONDITIONS o SENSITIVITIES USING PWR MODEL TO '
QUANTIFY UNCERTAINTIES
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0506H:LEH/050989 9 1
ELEMENTS.0F THE EPRI/W PROGRAM ON' CODE UNCERTAINTY (CONT'D)
TASK 5 OVERALL CODE UNCERTAINTY AS APPLIED TO PWR LOCA l
o COMBINE TASK 3 AND 4 FOR A PARTICULAR PWR !
o DEVELOP STATISTICAL APPROACH FOR UNCERTAINTY CALCULATION o CALCULATE 50TH AND 95TH PERCENTILE PCT TASK 6 APPLICATION OF MARGIN WITH NEW LOCA METHOD o SPECIFIC EXAMPLES TO SEE HOW LOCA MARGIN CAN BE USED, DIESEL DELAYS, SGTP MARGIN, CORE POWER 1
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USE OF BEST ESTIMATE METHODS o -IN ADDITION TO PROVIDING OPERATING MARGIN, ALSO !
PROVIDE MARGIN FOR INCREASED OPERATIONAL SAFETY IN SEVERAL AREAS.
REDUCED: VESSEL FLUENCE AND EMBRITTLEMENT INCREASED DIESEL RELIABILITY FOR LONG-TERM-COOLING OPERATING STRATEGIES WHICH REDUCE THE POTENTIAL FOR SG TUBE DAMAGE REDUCED EXPOSURE I
0506H:LEN/050989 11 L
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o WE BELIEVE THAT THE BEST ESTIMATE APPROACH BENEFITS THE NRC AND UTILITY SINCE CALCULATIONS ARE MORE REALISTIC REQUIRES QUANTIFICATION OF UNCERTAINTIES WHICH WERE NEVER PART OF APPENDIX K GIVES A "TRUE" READING OF PLANT MARGIN 1
IN THE LONG RUN, REDUCES NRC WORK LOAD ON i
LOCA, FREEING RESOURCES FOR OTHER ITEMS l
I 0506M:LEH/050969 12
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