ML20237A993
| ML20237A993 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 12/03/1987 |
| From: | Wagner D Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8712150395 | |
| Download: ML20237A993 (4) | |
Text
- - . _ _ - _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
"- December 3, 1987 l
Docket No. 50-301 j LICENSEE: Wisconsin Electric Power Company FACILITY: Point Beach 2
SUBJECT:
SUSCEPTIBILITY OF POINT BEACH 2 STEAM GENERATORS TO HIGH CYCLE i FATIGUE i 1
On November 4,1987, a meeting was held in the Bethesda, Maryland, offices of l Westinghouse to discuss the above topic. Meeting attendees are identified in Enclosure 1.
The purpose of the meeting was to discuss high cycle fatigue and how it pertained to Point Beach 2. Following the July 1987 tube rupture event at North Anna, l Westinghouse identified Point Beach 2 steam generators as potentially susceptible to high cycle fatigue, the mechanism which caused the North Anna tube rupture.
During the Fall 1987 Point Beach 2 refueling outage, the licensee performed eddy current testing on the potentially susceptible tubes in each steam generator to identify denting at the top support plate and to identify anti-vibration bar insertion depths. Those eddy current examination results provided input to the thermal-hydraulic, fatigue, vibration and local-flow analyses performed by Westinghouse for the Point Beach 2 steam generators.
Details of these analyses and Westinghouse acceptance criteria are identified i in Enclosure 2, which is a non-proprietary collection of handouts used by West-inghouse at the meeting.
Based on the analyses, Westinghouse concluded that no tubes in the Point Beach 2 I steam generators were susceptible to the tube fatigue failure similar to that which occurred at North Anna.
Original Signed By:
l David H. Wagner, Project Manager Project Directorate III-3 Division of Reactor Projects
Enclosures:
As stated cc: See next page DISTRIBUTION: ,
Docket Files- JRichardson l l
NRC PDR LShao )
Local PDR HConrad '
PDIII-3 r/f EMurphy KPerkins 01 DWagner 8712150395 PDR ADOCK P
h @PDR OGC-Bethesda EJordan JPartlow (ACRS(10)
Office: LA/PDIII-3 / 111-3 PD/PD 3 Surname: PKredtzer DWagner/tg KPerkins Date: 12/5/87 fr/4,/87 lb/3 /87 G-L
'. ]
.. . .; .. . l Mr. C. W. Fay Point Beach Nuclear Plant Wisconsin Electric Power Company Units 1 and 2 CC:
Mr. Bruce Churchill, Esq.
Shaw, Pittman, Potts- and Trowbridge 2300 N Street, N.W.
Washington, DC 20037 Mr. James J. Zach, Manager Point Beach Nuclear Plant Wisconsin Electric Power Company 6610 Nuclear Road .
Two Rivers, Wisconsin 54241
)
Town Chairman Town of Two Creeks Route 3 Two Rivers, Wisconsin 54241 Chairman Public Service Commissior, of Wisconsin Hills farms State Office Building Madison, Wisconsin 53702 i
Regional Administrator, Region III U.S. huclear Regulatory Commission Office of Executive Director for Operations.
799 Roosevelt Road Glen Ellyn, Illinois 60137 i Resident Inspector's Office l U.S. Nuclear Regulatory Commission 6612 huclear Road Two Rivers, Wisconsin 54241 l
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ENCLOSURE 1 XBETHESDALICENSINGOPERATIONS CONFERENCE ATTENDANCE i
i DATE N nuwse e 4; 1947 TIME M 4 4 - A V[e SUBJECT sr cuu lie 2_ S e b--.= m . . m n I'
CONTACT / NUMBER NAME COMPANY TELEPHONE 1 / birser $xeurm Se ax se hYW) m -23dd 2 kEiG ktf//dC- /dzetn/d bn rs/c s'tV 2z/ - 26/ 7 (o?rnst (K)) Rb D y/2 A E~6 /18 7 5
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~T. L . No uTM A y W GTB 4'< 2 - 3 74- 7 ~713 s TJ Ph l, w s rD w - s w. 77/o 6<.I$ 2r en A/A't^ c?//# Y92-YRS.3 7 bNTS& WC Yl~ O?2 RI'l 9/
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9 S' ^' O '#' Y W 2 /2 " Y b 0 ~ N'S~ Y 3 10TosePh [arbenarn los (Andn d 0'w)/orN ht4) Stb -sis 7 8' 11(e EsG{wbh flea %rK k x llAd (9t</} 6 II -6 ?ry 12 H6R6 OwcAh us P Ed 64 qu-7ecr 13 fm.m /t /h(v dS NR L 20, te t, c n.
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l ENCLOSURE 2 1
4
WEST 1}G 00SE CIASS 3 WCAP-11672 l
POINI PDOI IJNIT 2 STEAM GENERAER WBE: FATIGUE PRESDGATICN NOVD!BER 1987 i
WORK PERREMED IJNDER SDP CREER MK7D-7632A WESTINGHOUSE EI.ECIRIC CIRPCEATICH PJWER SYSTINS E'JSINESS INIT P. O. BOX 355 R.R21,PA 15230-0355 g
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A meeting was held on 11/4/87 between Wisconsin Electric Power Company, Westinghouse and the NRR Staff addressing the potential for tube fat.4gue failure in the Point Beach Unit 2 steam generators. The following agenda items were addressed during the meeting:
- 1. Review of the North Anna Unit 1 Fatigue Failure Mechanism and Criteria
- 2. Contributors to Fluidelastic Instability 3
Air Model Tests for Flow Peaking Effects 4 Point Beach Unit 2 Tube Fatigue Evaluation A copy of the slides presented by Westinghouse to the NRR staff is contained herein.
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l q., " 4 POINT BEACH UNIT 2 TURE FATIGUE IVALUATION NRC MEETING, NOVEMBER 4,1987
! AGLWDA FRIELING 9:00 INTRODUCTION / PURPOSE HOUTMAN -
9:15 REVIEW OF FAILURE MECHANISM & CRITERIA e PULLED TUBE EVALUATION
SUMMARY
e DEVELOPMENT OF 10% CRITERIA l e CONSERVATISM OF 10% CRITERIA PITTERLE 10:15 CONTRIBUTIONS TO FLUIDELASTIC INSTABILITY e TUBE DAMPING e IOCAL FMW PEAKING e IMPLIED STABILITY RATIOS FOR N. ANNA R9C51 CONNORS 11:00 AIR MODEL TESTS FOR FIDW PEAKING EFFECTS LUNCH POINT BEACH EVALUATION e CRITERIA FOR EVALUATION PITTERLE 12:30 e EC DATA AND AVB POSITIONS 1 e FI4W PEAKING FACTORS FOR POINT BEACH e STABILITY RATICS FOR CRITICAL ROWS HOUTFAN 1:15 e COMPARISON OF UNSUPPORTED TUBES TO R9C51 l e CURRENT FATIGUE USAGE OF WORST TUBE e CONCLUSIONS ALL 2:00 DISCUSSION l
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Stress Amplitude for brack Initiation
- Is Basedon Measurements Taken from the Examination of the Pulled Tube
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4 KSI < GA < 10 KSI
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The Allemaling Stress Leve1 Contributes to Evaluation of Leakage as the Crack Grows \
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. . Evaluation of Tube Rupture Mechanism KeyFraclography Analysis Results .
- High Cycle Fatigue Failure (>100 cycles)
From Inittstion to Separation l
- Outer Surface Crack initiation at 90* to the Plane of .
the'U.bendand Slightly Above the Top of the Top Tube Support Plate
- Crack Initiation Stress AmplitJdes in the Range of 4 ,
to 10 KSIIn the Presence of High Mean Stress .
- CrackPropsgation StressIntensityResches 60 KSidlnch at About 00* Hall Crack Angle from the l
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Evaluation of Tube Rupture Mechanism Steady State and Cyclic Stress Evaluations
- Crackinittstion-Cumulative Fatigue Usage orHigh Enough Stress Amp!Itudes In the Presence of Significant Mean Stress
- Crack Propagation-
- Effect ofincreasing Crack Size on Tube Behavior .
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- o Evaluation of Tube Rupture Mechanism
, i Crackinitiallon Considers!!cns
- Cperating Conditions -
- Assessment of Axisymmetric Denting'
- Mow Induced Vibration Mechanisms /
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s Evaluation of Tube Rupture Mechanism e a e
Operating Conditions
- Analysis Is based on the Westinghouse Design Specification for North Anna Unit 1 i
- The total number of normal and upset transient cycles that could have been experiencedin 9 calendaryears .
Is less than 10,000 cycles
- Alternating stress levels from these transients are ,
inoderste to low with a cniculated fatigue usage of '
'less than 0.009
- Number of cycles and fatigue usage are too low. .
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Evaluation of Tube Rupture Mechanism Assessment of Ax1 symmetric Denting -
.
- An inelsstic analysis of the R.9051 tube has been performed based on eddy current measurements with the axisymmetric denting componentof 2.5
- 1. ,
miss msximum radialdisplacement at the TSP c'enterline .
- 2. tapering to 0 mils at the top of the tube support piste ,
- Axisymmetric Denting produces boundary conditions which concentrate axist bending stress just above the top of the tube supportpiste
- This smallamount of axisymmetric denting can produce a residustmean stress equal to .
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Afeen stress is significant with a smallmagnitude of
- denting. .
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1 Evaluation of Tube Rupture Mechanism a
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Turbulence induced vibration is verylow t, e. ,
- Vibration frequencyis which wouldresultin ]
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1 year of operation at 75%
sysllability.
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- The RMS modal vibration amplitude for R9051is l
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- andis out of plane to the U bend -
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e Evaluation of Tube Rupture Mechanism
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Muld elastic instabilities have been observed .
- Vibration is out of plane to the U bend andis at n l r - s, t. -ss -
frequencyofy . .
which wouldresultis .
cycles in 1 year of operation at 75% sys!!ab!Ilty. .l l
- The bending stress amplitude for R9C51 for the !
first mode of vibration is{ ,
}c displacement .
A displacement of 100 mils results in a sitess of
- s, c .
= Underoff nominstconditions,Instabilityis -
possible Number of cycles andlocation of maximum stress are Consistent with the ruptured tube and the potentialexists
- for.sufficiently high stresses. -
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Evaluatioh of Tube Rupture Mechanism l
Potentialreasons forinstabilityin R9051 Reduced damping due to fixity of tube from denting at the top TSP
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- Localgeometry effect on the cross flow velocity,
. density or voldfraction .
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Evaluation of Tube Rupture Mechanism
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. The Probable Cause of Crack inittstforile Limited.
Displacement Fluidelsstic Instability
- Eddy current inspection confirms that no tube contact occurred with adjacent tubes in the spex region
- Test date confirms that displacements for unstable
- tubes remain limited for a given flow rate o
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Evaluation of Tube Rupture Mechanism tresses Required for Consistency with Fracture The crackgrowth analysis has producedan estlmste'of the stresses implied by the stristion spacing I
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- At crack Inlilation, a tube stress of 4 KSI to 10 KSI and the corresponding implied displa cement are
' required
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- At the half crack sngle, G s 90*, a str'ess intensity AKm 50 KSI Anch andthe corresponding displacement must be obtained .
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Evaluation of Tube Rupture Mechanism Initiation Stress andimplied DIspinoeinent .
l The impfled nomins! Initiation displacement ampfltude is obtained from the dynamic first mode response of the .
- da t.
conditions at the top tube U bend with dented .
supportpInte I
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The unit stress IsL ' . ,01 displacement at l the apex .
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Effect of Cracking on Tube Response As cracking progresses around the tube circumference . . .
- 1. the vibration amp!Itude of the tube w!!! Increase,
- 2. frequency of vibration willdecrease, and l 3. the frequency decrease causes a drop In critical velocity.
- 4. A drop In critical velocityIncreases tube Instab!Ilty.
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9 Evaluation of Tube Rupture Mechanism
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Propagation Stress andimplied DIspincement The crack growth analysis establishes the tube bending displacement needed to get a stress Intensity of 50 KS!dinch at a crack half angle of 90*
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- The dispincement requiredIs _
- st a crack half angle of 90* .
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Evaluation of Tube Ruptur.e Mechanism Displacement vs Crack Angle ,
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I J Evaluation of Tube Rupture Mectianism .
. l Conclusions i
- Normaland Upset Conditions are not a significant factor 1
- Denting provides a source of significant mean stress andreduces damping during tube vibration s
- Limited dispincement Fluidelsstic excitation provides the necessary dispisoement and stress
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- . amplitude to produce rupture of the tube at R9051 S -
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. Acceptance Criteria i
. . . GeneralApproach. ..
With' limited displacement fluid elastic instability thi probable cause, the generalapproach is to ...
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- 1. Reduce the effective velocity to below the -
criticalvelocity, or -
- 2. Reduce tube displacements sufficiently so that stresses become acceptable w
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Acceptance Criteria _
Dependence of Displacement (or Stress) o.n Stability Ratio Tes indicates thatan unstable tube e erlences a \
much Igherorderchangein displacement than the change In velocity or stability ratio. l
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= The log-log slope, s, of displace' ment versus
' to L stabilityratio ranges from] _
ormore.
- Since stress is lineady proportional to displacement, the ratio of the new stress,Q after a change in stability ratio, SR, to the old stress, % ,1s...
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Accep.tance Criteria Apparent kiinimum Fatigue Strength of the Row 9 Column S1 Tube The ininimurn. fatigue properties, stress amplitude ' '-
versus cycles to failure, for alloy 600 tubing at 600*F is... y y >
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t Acceptance Criteria Boundthe Problem The possible.ran
" be boundedby..ge 'ofinitiating stress amplitud
= The totatyears of operation, 9 years, which give)s the minimum stress amplitude, 5.6 KSI. .
- The maximum initiating stress impiledby the - - eLr fracture analysis - working backward from the _ ,
mil displacement for G=90*, the minimum ,
change in displacement is defined by the _
frequencyratio with n-1, do t. ~
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The maximum stressis .
Q = 9.5KSi 4
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Acceptance Criteria j t
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Assessment of Future Fatigue Usage.-- .
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- Minimuin stress case with a 5% reduction in .
stabilityratio,
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Q = 3.95KSI 1
. U = 0.0207peryear
- Maximum stress case with a 10% reduction in .
stability ratio, Q = . 3.96KSI U = O.0209peryear 1
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. . Acceptance Criteria Look at Varlations to valuate Conservadsm
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= Maximum stress case with fatigue curve and a 10% reduction in stability ratio U = 0.005peryear 7
s, c
- 9 years to fat 1with[ J fatigue anda 5%
reductionin stabilityratio, Tmin
- 7KSI .
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U = 0.0107peryear
= Maximum stress case with lowermean stress
.ands,e.10% reductionin stabiliti .
ratio, 0~ max
- 11.6KSIand
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U = 0.0142peryear .
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Acceptance Criteria \
Cumulative Fatigue Usage for Row 9 Column 51 Stress empfltude was a maximum during the most recent fuel cycle
. Normalized Stability Allemating . , d, c FuelCycle Ratio Stress Days Cyclesat _
a
~
- a. 6u, 7u 1.0 1.0 170
- b. 2,3,4 0.995 0.970 898 c 6,6u (95) 0.961 0.788 204 d 2(95),3(95),4(95) 0.949 0.728 25
- e. 5,6(95),6u(90),7U(90) 0.937 0.678 349 _
~
Totalcycles <- -
A cumuistive fatigue usage of 1.0 is obtained for a most recent stress ampiltude of 6660 psl and the most cumuistive usage 1
occurred during the second to the fourth fuel cycles.
Attemating FuelCycle Stress N n/N
~ '
6660 $1 l-a.
- b. 6460 c 5250 d 4850 * ~~
- e. 4520 - -
TotalUsage 1.004
..mma.mmm ----a.im m E irq uam-aga u um mii mnum ad d
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Acceptance Cdtena
- ~
Threshold Stress Amplitude for Continued. Crack Growth Reducing the stress amplitude to 4 KSI or less gives very low future usage peryear, but what if a
. small crack has been undetected and doesn1 leak?
- A 125 millength thru-wallcrack willnotgrow with an appliedbending stress of 4 KSI.
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Acceptance Criteria Conclusions
- Tube vibration stress amplitudes can be sufficiently reduced by a 10% reduction in stability ratio Future fatigue usage drops to less than 0.021 peryear with bounding calculations.
A currently cracked tube with a thru-wall crack up to i 125 mils long will not experience crack growth with the ,
nominal bending stress reduced to 4 KSI.
The 3 tress amplitude for the most recent fuel cycle at Row 9 Column 51 is calculated to be 6660 psiand the l
failure has been shown to have been developing over the operating period since the first fuel cycle when denting occurred.
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CONTRIBUTIONS To FWIDEIASTIC INSTABILITY PRIOR NORTH ANNA EVAIDATION {
e TWO POSSIBLE PATES LEADING TO INSTABILITY e IDW DAWPING PATH
- TOTAL DAMPING APPROACHES I4WER BOUND MECHANICAL DAMPING
- VERY LOW FLUID DAMPING e 14 CAL FLOW PEAKING PATH
- 14 CAL FI4W PEAKING ALONE LEADS TO INSTABILITY
- CONCURRENT WITH NOMINAL DAMPING FOR CIAMPED TUDE CURRENT ASSESSMENT e LOCAL FLOW PEAKING I ACTORS ESTABLISHED BY TEST e CAUSATIVE PATH FOR INSTABILITY ;
)
14 CAL FIDW PEAKING
- ., A,6
- TUBE DAMPING FOR ~
s OR DENTED TUBE WITH
- 25% UNCERTAINTY l
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.. _Ac Tube Damping for Suppolf Conditions to L Influence of .
Tube Support Conditions
. Reduction In MechanicalDamping l
. Reduction In Fluid Damping
- Elimination of Crevice Damping NominalDamping Reduction si ibe WEB
Measured Mechanical Damping s
for a Row 9 U bend In Air _tAlj i
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Damping vs Slip Void Fraction ,
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Figure 1 Test Equipment ,
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LOCAL FICW PEAKING CONSIDERATIONS FI4W PEAKING FROM NON-UNIFORM AVB INSERTION DEPTHS PEAKING FACTORS OBTAINED FROM AIR MODEL TESTS e PEAKING FACTOR DEFINED AS RATIO OF CRITICAL VEIDCITIES BETWEEN 2 AVB POSITIONS
- UNIFORM AVB INSERTION USED AS REFERENCE CRITICAL VII4 CITY APPLICATION OF AIR MODEL RESULTS TO STIAM-WATER
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W' FIctmE 1 1DCAL TEthCITT' FEAKIEC FACTOR IW U-SEND OF 30175 ARE 1 STEAM GENERATORS (TTFE I AND II AY3 INSERTION)
FI4W PEAKING FOR NORTH ANNA R9C51 AVB CONFIGURATION j TEST RESULT FOR R9C51 AVB CONFIGURATION
.. . 4, 6 e TEST FEAKING FACTOR = ~ ~
RELATIVE To UNIFORM Rio AVBS
.. - d, L
- FACTOR = APPLIED To STEAM FIDW WITH DAMPING EFFECT
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(, G e TEST PEAKING FACTOR = - -
REIATIVE TO UNIFORM R11 AVBS
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- FACTOR =
APPLIED TO STEAM FIbW WITH DAMPING EFFECT ESTIMATED STABILITY RATIO FOR NORTH ANNA R9C51 e CALCUIATED USING T S,
- S.R. =
- d : L, e INCORPORATING PEAKING FACTOR OF ' ;
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- S.R. = ,
l e INCORPORATING DAMPING UNCERTAINTY OF 25% !
S.R. =
STABILITY RATIO RANGE IMPLIED FROM TUBE FAILURE ANALYSIS .
- - s, L e BASED ON STRESS AMPLITUDE OF IMPLIED FROM FAILURE ANALYSIS - -
e VARIATION OF 8.R. WITH SIDPE OF AMPLITUDE VS. 8.R.
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FLUIDEIASTIC INSTABILITY CONCLUSIONS INSTABILITY CAUSED BY
. 46 1 e REDUCED TUBE DAMPING CAUSED BY DENTED, TURE CONDITIONS e ICCAL FI4W PEAKING DUI TO VARIABLE AVB INSERTION DEPTHS .
PREDICTED STABILITY RATICS CONSISTENT WITH VALUES IMPLIED FROM FAILURE ANALYSIS 9
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ATH0b N3DELING UPDATE REVISIONS To MODEL
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, R WIND TUNNEL TESTS ON CANTILEVER TUBE MODEL OBJECTIVE: Investigate the effects of tube /AVB fltup on flow- 4 f,6 Induced tube vibration. _
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WIND TUNNEL TESTS TO DETERMINE THE EFFECTS ON FLUIDELASTIC INSTABILITY OF COLUMNWISE VARIATIONS IN AVB INSERTION DEPTHS OBJECTIVE: Investigate the effects of variations in the insertion depths of AVBs in the vicinity of an unsupported U-bend tube on the initiation of fluidelastic vibration.
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POINT BEACH UNIT 2 EVALUATION To ASSESS THE UNSUPPORTED U-BENDS RELATIVE To THE FAILED TUBE AT NORTH ANNA UNIT 1, R9 C51 4 f
i TO IDENTITY TUBES THAT Do NOT HAVE STABILITY RATICS LESS THAN 90% OF NORTH ANNA UNIT 1, R9 C51, AS BEING TUBES AT RISH 4
i To EVALUATE THE APPARENT STRUCTURAL MARGIN OF TUBES THAT ARE NOT AT RISK COMPARED To NORTH ANNA UNIT 1, R9 C51 _4,f 9
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6 CRITERIA FOR TUBE FATIGUE EVALUATION NORYH ANNA POINT BEACH 1et s.k. REDUeTION CRITERIA UTILIIED ITTILIIED DEFINITION OF AVB SUPPORT 44f M
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,yAGNITUDE IDENTIFIED BY ANALYSIS 4,f, JAGNITUDE OBTAINED BY TEST2 4c 1
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POINT BEACH 2 EDDY CURRENT DATA NO TUBES WITH Wall THINNING INDICATIONS AT AVES e 100% INSPECTION OF ROWS VTO p 3 ev TUBES WITH0tfT AVB SU" PORT IN ROWS 8 TO 12 ARE DENTED J
DATA CBTAINID TO DEFINI AVB POSITIONS .
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- Au ho d REFERENCE NORTN ANNA 1 R9C51 S.C. A - FT. BEACH e R12C2, R12C91, R11C2, R11C3, R11C91, R10C3, R10C4 .
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S.G. B - PT. BEACH e R12C2, R12C91, R11C2, R91C2 e R10C5 e R10C46, R10C47 .
- VAf.,UESBASEDONPEAKINGREIATIVETOUNIFORMR11AVBINSERTION. -
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PointBeach 2 Evaluation Current Fatigue Usage
- For all tubes meeting the 10% criteria, the maximum stress is less than 4.0 KSI.
- The maximum stress ratio for an unsupported tube is 0.76 in l Row 11 resulting In a maximum stress ofless than...
4.0 (0.76) = 3.04 KSI
- The cumulative fatigue usage for this worst case is 0.081, i taking all cycles at the highest stress.
Normalized Fuel Stability Alternating Cy_cles _ s, t Cycle Ratio Stress Days st{ J 13 1.0 1.0 288 11,12 0.989 0.936 577 10 0.987 0.924 416 7,8 0.986 0.913 615 5,6 0.981 0.891 613 3,9 0.977 0.870 570 1,4 0.969 0.828 783 ~ '*
2 0.966 0.813 344
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POINT BEACH UNIT 2 EVALUATION
SUMMARY
AND CONCLUSIONS EDDY CURRENT INSPECTION e No WALL THINNING INDICATIONS AT AVBS (100% INSPECTION ROWS S TC 12)
= INDICATES IDW LIKELIHOOD OF FINIDEIASTICALLY UNSTABLE TURES e TUBES IN ROWS 8-I2 ARE DENTED e DATA OBTAINID FOR AVB POSITIONS
- MINIMAL INTERFIRINCE FROM DEPOSITS AVB POSITIONS e ROW 11 SUPPORTED EXCEPI FOR A FEW PERIPHERAL COLUMNS e MOST ROW 10 TURES SUPPORTED e AVB PENETRATION To R0W 8 i
ATHOS ANALYSIS TRENDS e MODEL 44 TENDS TOWARD IDWIR VElcCITIES AT INNIR ROWS COMPARED TO MODEL 51 e POINT BEACE VOID FRACIZONS 14WER THAN NORTH ANNA
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a POINT BEACH UNIT S EVA2ATION
SUMMARY
AND CONCESIONS 9
TURE VIERATION ASSESSMENT e GENERAL MODEL 44 VS. MODEL 81 COMPARISON
- MODEL 44 TUBE RADIUS, FREQUENCY FOR ROW 10 APPROXIMATELY EQUIVALENT TO ROW 9 FOR MODEL 81 e ROWS 1 9 ASSESSMENT
- ACCEPTABLE WITH IARGE MARGINS DUE TO INCREASED TUBE STIFTNESS e ROW 10 ASSESSMENT
- WWER VELOCITIES AND VOID FRACTIONS TRAN NORTH ANNA R9C51
- ACCEPTABLE WITHOUT AVB SUPPORT o GENERALLY ACCEPTABLE EVEN WITH 2 CAL F2W PEAKING AS HIGH AS NORTH ANNA R9C51 e ROWS 11 AND 12 ASSESSMENT 90TAL OF 6 UNSUPPORTED TURES IN ROW 11 AND 4 IN R0W 12 8.,OED OVER SOTH STEAM GENERATORS ONLY PERIPHERAL TUBES WITH NEGLIGIBLE POTENTIAL FOR IbCAL FLOW PEAKING e OVERALL ASSESSMENT MAXIMUM S.R. REIATIVE TO N. ANNA R9C81 = 0.88
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MAXIMUM STRESS RATIO REIATIVE TO N. ANNA R9C81 AT 0.9
- 8.R. = 0.76 MAXIMUM STRESS AMPLITUDE OF < 4 RSI WOULD NOT ItAD To FATIGUE FAI WRE IN 40 YEAR FIANT I.IFE CONCIDSIONS e POINT BEACH UNIT S ACCEPTABLE REIATIVE To '!M FATIGUE AT
- TOP TSP e No MODIFICATION OR PREVENTATIVE TURE PWGGING IS REQUIRED
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