NEI 97-06, Steam Generator Conditioning Monitoring Report

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Steam Generator Conditioning Monitoring Report
ML042820060
Person / Time
Site: Callaway Ameren icon.png
Issue date: 09/30/2004
From: Witt W
AmerenUE
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NEI 97-06, ULNRC05048
Download: ML042820060 (46)
v • d • e


Text

AmerenUE PO Box 620 Callaway Plant Fulton, MIO 65251 September 30, 2004 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 ULNRC05048 WAuieren Ladies and Gentlemen:

DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.

FACILITY OPERATING LICENSE NPF-30 STEAM GENERATOR CONDITION MONITORING REPORT The enclosed Report is submitted in accordance with NEI 97-06 Revision I reporting requirements which state that if the results of a steam generator inspection indicate greater than one percent of the inspected tubes in any steam generator exceed the repair criteria, a Condition Monitoring report containing results of tube pulls and in situ testing is to be submitted to the NRC within 120 days after the Reactor Coolant System reenters Hot Shutdown conditions. There were no tube pulls or in-situ testing performed on steam generators at the Callaway Plant during Refuel 13. These portions of the reporting requirement are not applicable and thus not included in this Report.

This letter does not contain new commitments.

Sincerely, Warren A. Witt Manager, Callaway Plant Enclosure a subsidiary efAmeren Corporatione

ULNRC05048 September 30, 2004 Page 2 Mr. Bruce S. Mallett Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Jack N. Donohew (2 copies)

Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 7E1 Washington, DC 20555-2738 Missouri Public Service Commission Governor Office Building 200 Madison Street PO Box 360 Jefferson City, MO 65102-0360 Mr. Jerry B. Uhlmann Director Missouri State Emergency Management Agency P.O. Box 116 Jefferson City, MO 65102

20440-10 (211812004) 4A ENGINEERING INFORMATION RECORD ARE VA Document Identifier 51 - 5044435 - 00 Title Steam Generator Condition Monitoring at RF 13 PREPARED BY: REVIEWED BY:

Name J. A. Begley Name V. F. Newman Signa a gze _,-DatA2 "s f Slgnaturu r Date V/G/o0 Technical Manager Statement: I Ials Reviewer Is Independent.

Remarks:

This report provides the details of a Condition Monitoring evaluation of steam generator tubing degradation at Callaway at the RF 13 inspection.

Page 1 oF44

51-5044435-00 Page 2 of 44 TABLE OF CONTENTS Page

1. Introduction 3
2. Condition Monitoring Results 4
3. Summary and Conclusions 27
4. References 28

51-5044435.00 Page 3 of 44 Section 1 INTRODUCTION This report describes condition monitoring evaluations of steam generator tubing at Callaway. The observed severity of degradation at the end of cycle, outage RF 13, was evaluated to determine if structural and leakage integrity requirements were maintained.

The scope of this evaluation included all the forms of tubing degradation observed at RF 13, specifically:

  • Wear at AVB Tube Support Locations
  • Expansion Transition Axial PWSCC
  • Expansion Transition Axial ODSCC
  • Expansion Transition Circumferential PWSCC
  • Expansion Transition Circumferential ODSCC
  • Combined Axial And Circumferential PWSCC at Expansion Transitions
  • Circumferential PWSCC Within the Tubesheet
  • Volumetric Degradation The observed degradation at the RF 13 outage was evaluated in a manner consistent with NEI 97-061, and EPRI guidelines2'3. The observed degradation did not present serious challenges to the deterministic structural margin requirement at the end of the last cycle of operation. The limiting structural requirement is a 3AP differential pressure of 3900 psi.

In terms of an overview of repair scenarios:

  • wear indications at tube supports are left Inservice if maximum depths are sized less than 40% of the wall thickness
  • all other Indications are repaired or plugged on detection.

The next section provides the results of condition monitoring evaluations for outage RF 13.

51-5044435-00 Page 4 of 44 Section 2 CONDITION MONITORING Condition monitoring evaluations relative to structural and leakage integrity are presented Inthis section. The following paragraphs present condition monitoring structural limits for axial cracks, circumferential cracks, volumetric degradation and wear scars for Callaway steam generator tubing. A discussion of leakage integrity then follows. Table 2.1 summarizes the number of Indications of tubing degradation discovered at RF 13 and Table 2.2 summarizes structural and leakage integrity evaluation results.

In terms of an overview of steam generator tubing degradation at Callaway 4, axial and circumferential PWSCC has been observed at top of the tubesheet hydraulic expansion transitions for the past seven cycles of operation. This is the primary degradation mode. Occasional Instances of ODSCC, both axial and circumferential, have been observed in this same region. Wear at AVB's is present, Approximately 1263 AVB wear indications among 574 tubes are present among the four steam generators. Wear growth rates are low leading to plugging several tubes per generator per inspection for each steam generator for depths exceeding the 40% TW limit. Small volumetric indications are observed on a sporadic basis. These Indications are plugged on detection as are all other degradation modes with the exception of wear at AVB's.

The inspection scope at RF13 was as follows:

100% Plus Point TTS Inspection "+21-X" in all SG Hot Legs, Distance X Depends on Location In the Tube Bundle, The Required Distance X to Demonstrate Leakage and Structural Integrity is Defined in WCAP-1 5932-P and Westinghouse analysis in Terms of Four Zones:

Zone A, X =5" Zone B, X = 7" ZoneCandDX=9"

51-5044435-00 Page 5 of 44

  • 100% Full Length Bobbin Exams inSGs A, B C and D
  • 100% Rows I and 2 U-bend RPC InSG A
  • 100 % Row 1 U-bends
  • 50% Row 12 U-bends (100% in S/Gs A and D)
  • 50% Row 17-21 U-Bends
  • UT of all Electro-sleeves (26) in SG C H/L
  • All Westinghouse Laser Welded Sleeves (43) InSG A
  • 20% Plus Point Inspection of Dents and Dings >2V Inall SGs at all Locations
  • 100% Plus Point Inspection of Dents and Dings > 5V in all SGs
  • Special Interest Plus Point Exams as Required No degradation was detected in Electro-sleeves and laser welded sleeves. The first ten rows of tubes at Callaway are thermally treated Alloy 600 tubing. Thermal treatment was performed after fabrication of the U-bends. Since this improves both the residual stress state and material resistance to stress corrosion, no degradation was expected In the Row I and Row 2 U-bends and none was observed. No degradation was expected In higher row U-bends and none was observed. No degradation was observed In the sampling Plus Point inspection of dents and dings.

Detected instances of degradation, as listed In Table 2.1, follow the expectations from past experience at Callaway. The total number of tubes plugged at RF13 for each steam generator is also listed in Table 2.1. The next section discusses a quantitative evaluation of degradation trends. Due to regulatory concerns with leakage Integrity from possible PWSCC deep within the tubesheet, inspection depth Issues were analyzed in detail and bounding leak rates from possible undetected degradation were conservatively determined 5. Leakage integrity was demonstrated via inspection and analysis as described In later paragraphs.

51-5044435-00 Page 6 of 44 Structural limits for axial cracks, circumferential cracks, volumetric degradation and wear scars for steam generator tubing at Callaway are described In the degradation assessment 4 for RF 13. These structural limits provide the framework needed for condition monitoring evaluations and operational assessments.

The combinations of wear scar lengths and depths leading to a 3AP burst pressure of 3900 psi are shown In Figure 2.1 for Callaway steam generator tubing. The upper curve, termed the structural limit curve using the nomenclature of the EPRI Steam Generator Degradation Specific Flaw Handbook 6 , is based on a best fit burst pressure equation and average, at temperature, material properties. The lower curve in Figure 2.1 is the Condition Monitoring Limit Curve. This curve includes NDE sizing uncertainties as well as uncertainties in material properties and In the burst pressure equation. The Condition Monitoring Limit curve shows the locus of NDE inferred degradation lengths and depths leading to a burst pressure of 3900 psi at 0.90 probability at 50% confidence. Indications with NDE inferred lengths and depths at or below the Condition Monitoring Limit Curve meet the required deterministic structural performance criteria for minimum degraded tube burst pressure. As Is shown below, all Instances of degradation at Callaway plot below CM curves and thus CM Is met via NDE sizing and analysis.

In applying NDE measured degradation dimensions to infer structural integrity, systematic errors, measurement uncertainties, and shape effects must be considered.

Historically, most NDE depth measurements refer to maximum depth. Figure 2.2 shows a plot of maximum wear scar depth from destructive examinations results versus NDE measured depths7 using the eddy current technique applicable to Callaway. The best fit straight line shows an Intercept of 2.92% TW and a slope of 0.96, resulting in a small systematic error. The scatter in actual depth about the best-fit line is normally distributed with a standard deviation of 3.52% TW. This value is termed the standard error of estimate In conventional straight-line linear regression evaluations. From Figure 2.2 it is seen that, at a measured NDE depth of 40% TW, the best estimate of actual maximum

51-5044435-00 Page 7 of 44 depth is 43.9% TW. Actual maximum depths will scatter about this value with a standard deviation of 3.52% TW. For wear Indications the systematic sizing error Is small. The slope value is about 1.0. This allows plotting of the best estimate structural limit and the CM curve on the same plot. The best estimate structural limit is a function of actual degradation length and depth. The CM limit curve is expressed as a function of NDE depth and NDE length readings. Often the systematic error in NDE sizing is such that NDE readings are significantly larger than the actual degradation depths and lengths. In these cases Inclusion of both the best estimate structural limit curve and the condition monitoring limit curve on the same plot would lead to confusion since the CM curve, referring to NDE readings, could plot above the best estimate structural limit curve which refers to actual physical dimensions. When compared on an equal basis such as best estimate actual degradation dimensions, CM curves are below best estimate structural limit curves by about 1.5 times the NDE depth sizing standard deviation.

z.3 >

A summary of NDE sizing uncertainties7 applicable to Callaway Is listed in Tablet2 4/0*04 The term modified in reference to ETSS 21409.1 Indicates that sizing data for laboratory produced flaws were deleted and sizing uncertainties were recalculated using data which is representative of actual service degradation. Additionally, the curve fitting procedure used did not allow a non zero intercept value which would have led to a very unrealistic slope.

Structural integrity typically depends on average degradation depth, not maximum depth. Maximum degradation depths and total degradation lengths are conservative bounds to structurally significant depths and lengths. If more accuracy is required, crack depth versus length profiles need to be considered. The EPRI Flaw Handbook6 provides a means of evaluating average depth from depth versus length profiles for predominantly axial degradation, whether crack-like or volumetric. Structurally significant lengths are also defined. For wear Indications structural depth Is conservatively estimated as equal to maximum depth and the structural length is conservatively set equal to the intersection length of the tube and support structure. If

51-5044435-00 Page 8 of44 depth/length profiles are not available, pulled tube examination results show that stress corrosion cracks have a roughly semi-elliptical shape leading to a structural average depth equal to the maximum depth divided by a factor of 1.252.

Condition monitoring structural limit plots are shown In Figures 2.3 through 2.6 for AVB wear scars at Callaway. Figures 2.3 through 2.6 show plotted points representing AVB wear scars observed at RF 13. The length plotted Is the bounding scar length for AVB wear which occurs when the tube and AVB do not have a perpendicular Intersection.

The plotted points fall well below the CM Limit curve. Required structural integrity is demonstrated. Since through wall tearing and burst will not occur at 3AP, leakage integrity at an FLBISLB differential pressure of 2560 psi is also demonstrated.

Figure 2.7 illustrates that OD volumetric Indications in steam generators B and C meet 3AP condition monitoring requirements. Of the total of 4 volumetric indications, 3 were located at tube support plates and I was located near the top of the tubesheet. All are low level indications in terms of extent, depth and signal amplitude. These Indications meet both structural and leakage integrity requirements by a wide margin. The tube support indications are believed to be distorted wear indications and the OD Indication near the top of the tubesheet is probably some combination of IGA and ODSCC.

Axial PWSCC Indications were all located at the top of tubesheet expansion transition and all had very short lengths. The maximum Indication length was 0.25 Inches.

Considering material property, burst equation and NDE sizing uncertainties an axial PWSCC crack can be 0.275 Inches long and 100% TW and meet 3AP condition monitoring structural integrity requirements. All axial PWSCC Indications thus meet condition monitoring structural Integrity requirements. The same conclusion is evident from the distribution of Plus Point voltages shown in Figure 2.8. Only 2 axial PWSCC indications exhibited a voltage greater than the 1.5 volt threshold value In order to require NDE sizing. Figure 2.9 shows that the NDE measured length and depths demonstrate 3AP structural Integrity.

51-5044435-00 Page 9 of 44 Axial ODSCC indications were all located near expansion transitions. Figure 2.10 shows that all but 1 indication were below the Plus Point voltage threshold where NDE sizing was required. This confirms the low level of degradation severity for both OD and IDaxial indications. Figure 2.11 illustrates that the NDE measured depth and length for the 1 OD indication above the structural sizing threshold demonstrates condition monitoring 3AP structural integrity.

Based on data in the EPRI Steam Generator In Situ Pressure Test Guidelines2, axial PWSCC Indications must exhibit a Plus Point voltage of 2.5 volts before leakage Integrity at postulated FLB/SLB conditions becomes an issue or sizing Is required. The maximum Plus Point voltage for all observed axial PWSCC Indications was 1.73 volts.

See Figure 2.8. Thus, leakage integrity is demonstrated. The same statement holds true of axial ODSCC indications. Figure 2.10 shows that the maximum observed Plus Point voltage is well below the 1.0 volt leakage threshold value.

A total of 33 circumferential PWSCC Indications were found in the vicinity of the top of tubesheet expansion transitions. Only 3 circumferential PWSCC Indications were found at some distance below the expansion transition as opposed to about 32 In the last inspection. All Indications exhibited limited circumferential extent. The maximum NDE PDA value was 19 compared to the condition monitoring limits of 75 NDE PDA. Hence, the degradation found met condition monitoring structural Integrity requirements by a large margin. Plus Point voltage levels were all below 1.0 volts satisfying both SAP structural integrity and FLB/SLB leakage integrity requirements on a voltage threshold basis as described in the Callaway RF13 Degradation Assessment 4 . See Figure 2.12.

Crack profiling of circumferential indications was performed even though not required.

NDE PDA values are plotted on the x axis of Figure 2.13. The large margin to the CM limit of 75 NDE PDA Is Illustrated.

A total of 9 indications of OD circumferential cracking were found at RF 3. All of these Indications were In the vicinity of expansion transitions. As In the case of PWSCC circumferential indications, the circumferential extent, PDA values and Plus Point

51-5044435-00 Page 10 of 44 voltage level of ODSCC circumferential iindications are small. The largest circumferential extent is 150 degrees, the largest PDA value is 9.8 versus a condition monitoring limit of 62 and the largest Plus Point voltage Is 0.27 volts. The very mild nature of ODSCC circumferential degradation is illustrated InFigures 2.14 and 2.15. On a voltage basis alone, both 3AP structural integrity and FLB/SLB leakage Integrity condition monitoring requirements are demonstrated.

There were two instances of combined axial and circumferential PWSCC Indications near expansion transitions. Figure 2.16 and 2.17 present Plus Point terrain maps for the largest of the two occurrences of combined cracks. The configuration Is essentially VL" shaped with some gap between the axial and circumferential cracks. The cracks are small and individual Plus Point voltages, 0.78 volts maximum, are well below the NDE sizing thresholds for either 3AP structural concerns or FLB/SLB leakage possibility for either axial or circumferential cracks. Additionally, there are extensive burst test data8 for combined axial and circumferential cracks near expansion transitions. Figure 2.18 illustrates the very high burst pressures for small axial and circumferential ID cracks in close proximity. Burst pressures are about twice the 3AP value demonstrating a large margin of structural integrity.

Circumferential PWSCC sites may exist at depths within the tubesheet that have not been inspected with the Plus Point probe. There is no condition monitoring FLB/SLB leakage contribution from detected degradation or undetected degradation within inspected regions. A bounding accident leakage value for undetected degradation in regions that have not been inspected has been determined and reported in WCAP-15932-T 5. This bounding value is 0.44 gpm.

In summary, condition monitoring structural and leakage integrity requirements are shown to have been met via analysis. The limiting structural Integrity requirement of a minimum degraded tube burst strength of 3 AP is met. The bounding projected leak rate at limiting accident conditions Is0.44 gpm which is below the 1.0 gpm limit. The only degradation sites where leakage is possible was well within expanded regions

51-5044435-00 Page 11 of44 deep In the tubesheet. Measured leakage at normal operating conditions was 0.09 gpd, well below the 75 gpd limit. Condition monitoring results are summarized InTable 2.2 Table 2.1 Summary of Indications at the RF 13 Inspection Degradation SG A SG B SG C SG D Mechanism AVB Wear 0 Plugged Tubes 9 Plugged Tubes 6 Plugged Tubes 0 Plugged Tubes (249 Total (352 Total (343 Total (319 Total Indications) Indications) Indications) Indications)

Expansion 77 4 18 2 Transition Axial (1mixed mode) (I mixed mode)

PWsCC Expansion 0 2 0 7 Transition Axial ODSCC Expansion 26 0 6 4 Transition (I mixed mode) (I mixed mode)

Circumferential PWSCC Expansion 0 2 3 4 Transition Circumferential ODSCC Circumferential 0 0 1 2 PWSCC Deep within the Tubesheet Crevice Volumetric 0 3 1 0 Degradation Total Tubes 100 19 32 17 Plugged

51-5044435-00 Page 12 of 44 Table 2.2 Summary of Condition Monitoring Results Leakage Integrity Degradation Mechanism Structural Integrity Limiting SIG Leak Rate (cpmORT)

Axial PWSCC at Expansion Passed via Analysis 0 Transitions Axial ODSCC at Expansion Passed via Analysis 0 Transitions Circumferential PWSCC At Passed via Analysis 0 Expansion Transitions Circumferential ODSCC At Passed via Analysis 0 Expansion Transitions Circumferential PWSCC Deep Passed via Analysis OA4 gpm maximum, within the Tubesheet Crevice bounding analysis for undetected degradation deep within the tubesheet Volumetric Degradation Passed via Analysis 0 Wear Passed via Analysis 0

51-5044435400 Page 13 of 44 Table 2.3 NDE Sizing Relationships and Uncertainties Applicable to Callaway Mechanism ILocation Technique Sizing Equations NDE (ETSS#) Uncertainty Depth:

Hot Leg TTS 20511.1 y= 0.87x- 5.46 11.3 PWSCC Axial (Plus Length:

Point) y=1.18x-0.01 .0.16 Average Depth:

Y=0.36x+1 8.9 7.60 Depth:

Hot Leg 20510.1 y=0.60x+20.4 20.3 Circumferential Length:

PWSCC (Plus Point) y=1.Olx+0.17 0.29 PDA:

y=0.81x+3.80 7.69 Maximum Depth:

Hot Leg TTS Axial 21409.1 y=0.90x 31.6 ODSCC (Plus Point) (modified) Length:

Y-l15x+0.024 0.22 PDA:

y=0.89x 22.5 Hot Leg TTS Circumferential EPRI PDA 14.3 ODSCC (Plus Point) 107197 Y=1.Ox AVB Wear 96004.3 Maximum Depth: 3.52 (Bobbin) y=0.96x+2.92 Volumetric OD 21998.1 Maximum Depth: 628 Degradation y=1.02x+5.81 (Plus Point)

51-5044435-00 Page 14 of 44 This Page Intentionally Left Blank

51-5044435-00 Page 15 of 44 Wear Scars, ETSS 96004.3 100 90 80 70 60 4-.

w a 50 E

E 40 x

30 20 10 0

0 0.5 1 1.5 2 2.5 3 Structural Length, Inches Figure 2.1 Structural Limit Curves Applicable to Wear Degradation

51-5044435-00 Page 16 of 44 100-90 80.

70*

4 60.

E 50 -I.

E 40 -

30 - 4 4 4

20. *4* 4 0 g . .

0 10 20 30 40 50 60 70 80 90 10(

NDE Measured Maximum Depth, %TW Figure 2.2 Actual Depth Versus NDE Measured Depth, Wear Scar Geometry ETSS 96004.3

51-5044435-00 Page 17 of 44 Wear Scars SIG A, ETSS 96004.3 100 90 80 70 60 a)

D l E 50 E

40 z 30 20 10 0

0 0.5 1 1.5 2 2.5 3 Structural Length, inches Figure 2.3 Structural Limit Curve for Wear Scars at Callaway for S/G A RF 13 Inspection Data

51-5044435-00 Page 18 of 44 Wear Scars SIG B, ETSS 96004.3 100 90 80 ...1.... - - .-...-------. . ............

l estEtim ate Structural Limit 70

.C]

60 - . - .-. - - .

a) Condition Monitoring at 0.90 Probabilit 50 E

40 __ .................

z 30 ........ _....., .- ' '''A' 20 ~L l _ _

10 0

0 0.5 1 1.5 2 2.5 3 Structural Length, Inches Figure 2.4 Structural Limit Curve for Wear Scars at Callaway for S/G B RF 13 Inspection Data

51-5044435-00 Page 19of44 Wear Scars SIG C, ETSS 96004.3 100 90 80 70 60 a)

.E 50 0x E 40 w

30 20 10 0

0 0.5 1 1.5 2 2.5 3 Structural Length, Inches Figure 2.5 Structural Limit Curve for Wear Scars at Callaway for SIG C RF 13 Inspection Data.

51-5044435-00 Page 20 of 44 Wear Scars SIG D, ETSS 96004.3 100 90 80 Best Estimate Structural Limit 70 60 ... .. -.

........-...... -. ...i.....

lCondition Monitoring at 0.90 Probability 50 0

E 40 _ ........ ...

A 30 20

_ _. _ I _ . _ . _ I____.__

10 0

0 0.5 1 1.5 2 2.5 3 Structural Length, Inches Figure 2.6 Structural Limit Curve for Wear Scars at Callaway for S/G C RF 13 Inspection Data.

51-5044435-00 Page 21 of 44 100 90

_ _ ._ _ .1-._ _

80

.~~~

~ ~ L..._ §__ __ 1.....

70

._ . I 60 t--.-- I 0

E 50

, ConditionMonitoring at 0.90 Probability xCu 40 4 I wi - 1,1-- ....

O 30 z -.. _.__. .... .._- ..

20 10 ,  : I 0

0 0.5 1 1.5 2 2.5 3 NDE Length, inches Figure 2.7 Condition Monitoring -Plot For Volumetric Degradation

51-5044435-00 Page 22 of 44 1

0.9 0.8 0

.0 0.7

  • a 5 0.6 ax 0.5 5.

0.4 E

3 0.3 0.2 0.1 0

0 0.5 1 1.5 2 2.5 3 Axial PWSCC Indication Plus Point Volts Figure 2.8 Distribution of Plus Point Voltages for Axial PWSCC Indications

51-5044435-00 Page 23 of 44 100 90 80 Condition Monitoring at

............ 1_ _. ...... _0.90 Probabil........ . ..

70 4..

C, 60 E 50 E

40 -.....-.-. .-................. .............

0 z 30 20 -. ... L............. ...........

. . I 10 0

0 0.5 1 1.5 2 2.5 3 NDE Length, inches Figure 2.9 Condition Monitoring Plot for Axial PWSCC Indications

51-5044435-00 Page 24 of 44 1

0.9 0.8 0 0.7

.0 0.6

.a 0.5 0.4 E

m 3 0.3 0.2 0.1 0

0 0.2 0.4 0.6 0.8 1 1.2 Axial ODSCC Indication Plus Point Volts Figure 2.10 Distribution of Plus Point Voltages for Axial ODSCC Indications

51-5044435-00 Page 25 of 44 100 90 80 70

_ [Condition Monitoring at 0.90 Probabilityj 0aN, 60 D

E E 50

.I_.....~..]. -... ._

0 z 40 w

30 . ,--

I ____.__-----------

20 10 0 4., a 0 0.5 1 1.5 2 2.5 3 NDE Length, Inches Figure 2.11 Condition Monitoring Plot for Axial ODSCC Indications

51-5044435-00 Page 26 of 44 1

0.9 0.8 0 0.7 0-Co 4-W 0.6 0.5 0.4 E

V) 0.3 0.2 0.1 0

0 0.2 0.4 0.6 0.8 1 1.2 ID Circumferential Indication Plus Point Volts Figure 2.12 Distribution of Plus Point Voltages for Circumferential PWSCC Indications

51-5044435-00 Page 27 of 44 9000 8000

_F r WU

= 6000 tL a.

I..

f 5000 m

oC 4000 0

r 3000 0

0 5 2000 1000 0

0 10 20 30 40 50 60 70 80 90 100 NDE PDA Value Figure 2.13 Condition Monitoring Burst Pressure versus NDE PDA Values for Circumferential PWSCC Indications

51-5044435-00 Page28 of 44 I

0.9 0.8 0.7 CD 0 0.6

.0 1w 0.5

  • a 3

E 0.4 C) 0.3 0.2 0.1 0

0 0.2 0.4 0.6 0.8 1 1.2 OD Circumferential Indication Plus Point Volts Figure 2.14 Distribution of Plus Point Voltages for Circumferential ODSCC Indications

51-5044435-00 Page 29 of 44 9000 8000 *

-7000 Condition Monitoring at 0.90 Probability 6000-IL E2 5000 .- .I C 3Delta P E 0 0. . . . . . . . . . . . . _, _. _ . . . . . . . . . . . . . . . . .

0 n

Oc3000-C.\

0 C 2000 -

CM Limit 1000 \

0 10 20 30 40 50 60 70 80 90 100 NDE PDA Value Figure 2.15 Condition Monitoring Burst Pressure versus NDE PDA Values for Circumferential ODSCC Indications

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.L 3 psi 83=psI Figure I- Sketches of Axd2 and Circumferentil CGcs In Westinghouse RP301-9 Specimens Figure 2.18 Sketches of Combined Axial and Circumferential Cracks at Expansion Transitions Illustrating High Measured Burst Pressures.

51-5044435.00 Page 33 of 44 Section 3

SUMMARY

AND CONCLUSIONS Condition monitoring evaluations of steam generator tubing at Callaway were performed using inspection results from outage RF13. The observed severity of degradation at the end of cycle was evaluated to determine if structural and leakage integrity requirements were maintained.

The scope of this evaluation included all forms of tubing degradation:

  • Wear at AVB tube Support Location
  • Expansion Transition Axial PWSCC
  • Expansion Transition Axial ODSCC
  • Expansion Transition Circumferential PWSCC
  • Expansion Transition ODSCC
  • Combined Axial And Circumferential PWSCC at Expansion Transitions
  • Circumferential PWSCC Within the Tubesheet
  • Volumetric Degradation Condition monitoring via analysis showed that 3AP deterministic structural margins and FLB/SLB leakage integrity were maintained during the last cycle of operation. Degraded tubes maintained a minimum burst pressure above 3900 psi. The worst case leak rate at postulatged accident conditions Is0.44 gpm compared to a 1.0 gpm limit. Measured leakage at normal operating conditions was 0.09 gpd compared to a 75 gpd administrative limit.

51-5044435-00 Page 34 of 44 Section 4 REFERENCES

1. "Steam Generator Program Guidelines", Nuclear Energy Institute, NEI 97-06, December 1997.
2. "Steam Generator In Situ Pressure Test Guidelines", EPRI Report TR-107620-R2, August, 2003.
3. "Steam Generator Integrity Assessment Guidelines: Revision 1", EPRI Report TR-107621-RI, March, 2000.
4. "Callaway Degradation Assessment, Refuel 13, Framatome-ANP Report 51-5038803-00,2004.
5. "Improved Justification of Partial-Length RPC Inspection of Tube Joints of Model F Steam Generators of Ameren UE Callaway Plant," Westinghouse Electric Company, Pittsburgh, Pa., USA., WCAP-15932-T, September, 2002.
6. "Steam Generator Degradation Specific Management Flaw Handbook", EPRI Report 1001191, March, 2001.
7. "Performance Demonstration Data Base, Appendix A, Technique Specification Sheets",

Electric Power Research Institute, Palo Alto, CA, June, 2002.

8. "PWR Steam Generator Tube Repair Limits: Technical Support Document for Expansion Zone PWSCC in Roll Transitions-Rev. 2", EPRI Report NP-6864_L-Rev. 2, 1993.

51-5044435-00 Page 35 of 44 Appendix Tabular Summary of Tube Degradation

51-5044435-00 Page 36 of 44 ID Axial Flaws Maximum Axial Plus Phase Depth Length Location Point Angle Cal SGID Row Column Indication (%TW) (Inches) Elevation (inches) Volts (degrees) Group 1A 11 33 SAI 45 0.16 TSH 0.05 0.56 23 29 1A 11 48 SAI 71 0.16 TSH 0.06 0.81 21 34 1A 11 48 SAI 71 0.16 TSH -0.35 0.81 22 34 1A 11 53 SAI 56 0.13 TSH 0.14 0.80 21 46 1A 11 54 SAI 33 0.16 TSH 0.10 0.59 12 46 1A 11 57 SAI 71 0.18 TSH 0.11 0.81 22 47 1A 12 59 SAI 56 0.13 TSH 0.08 0.36 22 49 1A 12 74 SAI 73 0.13 TSH 0.12 1.15 22 21 1A 12 96 SAI 42 0.15 TSH 0.00 0.87 18 1 1A 13 51 SAI 30 0.16 TSH 0.00 0.42 12 47 1A 14 60 SAI 43 0.13 TSH 0.10 0.64 17 49 1A 15 40 SAI 39 0.18 TSH 0.04 0.54 17 29 1A 16 55 SAI 56 0.13 TSH -0.18 0.99 17 46 1A 16 57 SAI 97 0.16 TSH 0.10 0.57 34 47 1A 16 68 SAI 43 0.16 TSH 0.10 0.62 15 50 1A 17 36 SAI 71 0.16 TSH 0.06 1.02 25 29 1A 18 20 MAI 39 0.16 TSH 0.06 0.77 16 40 1A 18 47 SAI 63 0.21 TSH 0.06 1.14 22 27 1A 19 44 MAI 75 0.24 TSH 0.03 1.34 18 26 1A 19 50 SAI 45 0.18 TSH 0.05 0.63 17 27 1A 19 67 SAI 71 0.16 TSH 0.15 0.82 25 50 1A 19 86 SAI 29 0.20 TSH 0.09 0.75 15 9 1A 19 97 SAI 49 0.20 TSH 0.04 1.00 22 8 1A 19 100 SAI 39 0.17 TSH -0.06 0.61 18 7 1A 20 67 SAI 36 0.13 TSH 0.12 0.48 14 16 1A 20 85 SAI 77 0.17 TSH 0.10 1.10 26 10 1A 21 36 SAI 71 0.16 TSH 0.09 0.74 21 23 1A 21 46 MAI 16 0.16 TSH 0.05 0.82 18 25 1A 21 52 MAI 59 0.21 TSH 0.09 1.63 23 28

51-5044435-00 Page 37 of44 Axial Flaws (continued)

Maximum Axial Plus Phase Depth Length Location Point Angle Cal Row Column Indication (%TW) (inches) Elevation (inches) Volts (degrees) Group iA 22 38 SAI 39 0.11 TSH 0.15 0.56 15 26 1A 22 52 MAI 59 0.18 TSH -0.09 0.79 22 27 1A 22 68 SAI 36 0.12 TSH 0.04 0.47 15 16 1A 22 71 MAI 86 0.15 TSH 0.07 0.53 30 13 1A 22 90 MAI 46 0.15 TSH -0.03 0.97 19 8 1A 23 71 SAI 39 0.15 TSH 0.14 0.59 18 14 1A 23 88 SAI 49 0.17 TSH -0.03 0.57 18 10 1A 23 94 MAI 32 0.15 TSH 0.09 0.63 22 7 1A 24 101 MAI 57 0.15 TSH 0.08 0.77 19 7 1A 25 66 MAI 26 0.12 TSH 0.10 OA6 21 16 1A 26 43 SAI 33 0.16 TSH 0.07 0.77 14 25 1A 26 52 SAI 56 0.13 TSH 0.11 0.35 16 27 1A 26 56 SAI 67 0.18 TSH 0.05 1.24 25 28 1A 26 72 SAI 23 0.12 TSH 0.06 0.80 12 11 1A 27 73 SAI 46 0.12 TSH 0.00 0.88 15 11 1A 27 75 SAI 46 0.15 TSH 0.06 0.64 16 12 1A 27 85 SAI 65 0.15 TSH 0.06 0.84 17 9 1A 27 88 SAI 73 0.15 TSH 0.03 0.94 22 9 1A 30 45 SAI 45 0.18 TSH -0.02 0.59 19 25 1A 31 53 MAI 45 0.16 TSH 0.11 0.86 22 28 1A 33 100 SAI 36 0.20 TSH 0.03 0.46 13 7 1A 35 63 SAI 42 0.10 TSH 0.05 0.64 18 17 1A 35 108 SAI 46 0.20 TSH 0.05 0.73 20 5 1A 36 99 SAI 49 0.22 TSH 0.10 0.96 21 8 1A 36 102 SAI 82 0.18 TSH 0.10 0.63 24 6 1A 37 103 SAI 42 0.17 TSH 0.05 0.58 17 5 1A 38 89 MAI 26 0.17 TSH 0.11 0.55 19 7 1A 38 97 SAI 21 0.18 TSH 0.14 0.50 13 7 1A 39 89 SAI 42 0.20 TSH 0.04 0.92 18 8

51-5044435-00 Page 38 of 44 IDAxial Flaws (continued)

Maximum Axial Plus Phase Depth Length Location Point Angle Cal SG ID Row Column Indication (%T}W) (inches) Elevation (inches) Volts (degrees) Group 1A 40 51 SAI 67 0.18 TSH 0.09 0.67 18 27 1A 40 53 SAI 71 0.16 TSH -0.01 0.81 17 27 1A 40 58 SAI 45 0.15 TSH 0.03 0.53 16 29 1A 40 60 SAI 29 0.15 TSH 0.08 0.60 15 17 1A 41 85 SAI 53 0.15 TSH 0.10 0.99 19 10 1A 41 86 SAI 18 0.15 TSH 0.10 0.53 10 9 1A 42 54 SAI 52 0.16 TSH 0.04 0.45 16 28 1A 42 57 SAI 63 0.18 TSH 0.03 0.91 18 30 1A 44 54 MAI 59 0.16 TSH 0.06 0.97 17 28 IA 45 71 SAI 63 0.16 TSH 0.01 0.36 13 13 1A 45 74 MAI 46 0.18 TSH 0.08 1.19 31 11 1A 45 82 SAI 36 0.15 TSH 0.05 0.71 13 9 IA 50 61 MAI 86 0.13 TSH 0.06 1.15 26 18 IA 50 62 MAI 42 0.20 TSH 0.05 0.63 16 17 1A 51 55 SAI 45 0.13 TSH -0.06 0.87 16 27 IA 54 61 SAI 45 0.16 TSH 0.11 0.72 16 33 1A 55 60 SAI 77 0.15 TSH 0.17 0.52 25 17 1A 55 61 MAI 95 0.15 TSH 0.14 1.17 24 18 1B 11 53 SAI 100 0.20 TSH 0.08 0.76 33 23 1B 13 103 SAI 81 0.17 TSH 0.04 0.35 29 5 1B 15 53 SAI 93 0.15 TSH 0.12 0.23 41 23 1B 39 61 SAI 96 0.17 TSH 0.12 0.89 39 19 1C 17 57 SAI 59 0.14 TSH 0.13 0.53 22 53 1C 17 97 SAI 44 0.16 TSH -0.05 0.29 26 41 1C 19 52 SAI 97 0.14 TSH 0.06 0.76 38 51 1C 20 6 SAI 97 0.16 TSH 0.13 0.43 31 9 1C 20 24 SAI 93 0.16 TSH 0.20 0.80 42 10 1C 20 44 SAI 81 0.16 TSH 0.02 0.52 28 22 IC 25 17 SAI 100 0.13 TSH 0.09 0.60 35 10

51-5044435-00 Page 39 of 44 IDAxial Flaws (continued)

Maximum Axial Plus Phase Depth Length Location Point Angle Cal SGID Row Column Indication (0/JTW) (inches) Elevation (inches) Volts (degrees) Group 1C 26 71 SAI 70 0.12 TSH 0.08 0.25 29 33 IC 28 33 SAI 99 0.11 TSH 0.04 0.24 29 21 IC 30 80 SAI 77 0.14 TSH 0.06 0.87 26 34 IC 31 74 SAI 50 0.14 TSH 0.00 0.47 15 34 1C 34 13 SAI 95 0.16 TSH 0.09 0.50 34 12 IC 40 52 SAI 99 0.18 TSH 0.13 0.97 31 18 IC 41 20 SAI 75 0.13 TSH 0.00 0.88 24 11 IC 41 62 SAI 93 0.16 TSH 0.11 0.64 43 31 1C 43 22 SAI 97 0.18 TSH -0.02 1.73 38 12 IC 53 83 SAI 60 0.14 TSH 0.01 0.51 18 30 ID 11 67 MAI 68 0.13 TSH 0.14 0.53 29 31 ID 33 70 SAI 67 0.15 TSH 0.02 0.28 28 24

51-5044435-00 Page 40 of 44 OD Axial Flaws Maximum Axial Plus Phase Depth Length Location Point Angle Cal SGID Row Column Indication (%16TW) (inches) Elevation (Inches) Volts (degrees) Group lB 11 53 SAI 100 0.20 TSH 0.35 0.23 92 23 1B 15 65 SAI 0 0.15 TSH 0.26 0.13 92 22 1B 49 39 SVI 7 0.28 TSH 0.11 0.13 82 33 ID 11 61 SAI 71 0.20 TSH 0.49 0.45 72 31 ID 11 66 SAI 47 0.19 TSH 0.32 0.22 90 30 ID 12 64 SAI 51 0.20 TSH 0.49 0.16 71 30 ID 13 63 SAI 51 0.15 TSH 0.38 0.08 104 50 ID 14 59 SAI 48 0.14 TSH 0.19 0.25 96 49 ID 14 60 MAI 36 0.16 TSH 0.24 0.13 81 28 ID 17 62 SAI 55 0.15 TSH 0.23 0.29 81 28

51-5044435-00 Page 41 of 44 IDCircumferential Flaws Maximum Circumferential Plus Phase Depth Extent Elevation Point Angle Cal SGID Row Column Indication (%TW) (degrees) PDA Location (inches) Volts (degrees) Group IA 16 65 SCI 94 35.1 5.4 TSH 0.18 0.29 25 50 IA 19 74 SCI 53 43.4 3.9 TSH 0.15 0.51 15 11 IA 20 52 SCI 18 33.8 0.8 TSH 0.08 0.54 10 27 IA 21 85 SCI 99 35.1 6.3 TSH 0.13 0.37 10 9 1A 23 71 SCI 57 35.1 3.1 TSH -0.25 0.56 19 14 IA 23 83 SCI 28 52.7 1.8 TSH 0.02 0.32 17 10 1A 30 61 SC] 100 35.1 2.7 TSH 0.1 0.36 15 18 1A 30 96 MMI 86 52.6 7.5 TSH 0.11 0.78 16 8 1A 32 52 SCI 97 42.4 7.0 TSH 0.08 0.37 12 27 1A 32 61 SCI 88 35.2 4.7 TSH -0.17 0.28 19 18 IA 32 93 SCI 99 17.5 1.9 TSH 0.06 0.54 13 8 IA 33 69 SCI 81 42.3 5.2 TSH 0.05 0.47 9 16 IA 35 53 MCI 35 67.7 3.0 TSH 0.11 0.50 17 28 1A 35 94 SCI 34 34.7 1.4 TSH 0.12 0.36 12 7 IA 38 91 SCI 57 35.1 3.2 TSH 0.13 0.48 8 7 1A 39 84 SCI 28 41.9 1.8 TSH 0.1 0.16 20 9 IA 41 62 MCI 53 117.1 4.1 TSH 0.11 0.44 20 17 IA 43 57 SCI 86 33.9 3.7 TSH 0.05 0.46 9 29 1A 43 62 SC! 40 34.7 1.4 TSH -0.03 0.47 18 17 1A 44 50 SCI 79 33.9 4.6 TSH 0.04 0.70 18 28 1A 46 59 MCI 79 118.6 8.6 TSH 0.11 0.61 13 30 IA 46 74 SCI 97 34.7 5.4 TSH 0.11 0A9 19 12 1A 47 73 SCI 95 43.4 8.9 TSH 0.04 0.61 18 12 IA 49 66 SCI 95 26 3.1 TSH -0.03 0.68 16 18 1A 51 62 MCI 100 156.2 18.7 TSH 0.06 0.60 27 18 1A 51 80 SCI 99 35.2 3.4 TSH -0.13 OAO 10 12 1C 12 48 SCI 97 41.4 5.2 TSH -0.09 0.26 94 51 IC 16 28 SCI 69 37.7 3.3 TSH 0.08 0.55 22 8

51-5044435-00 Page 42 of 44 ID Circumferential Flaws (continued)

Maximum Circumferential Plus Phase Depth Extent Elevation Point Angle Cal SG ID Row Column Indication (%/6TW) (degrees) PDA Location (inches) Volts (degrees) Group lC 28 72 SCI 94 41.4 5.7 TSH 0.15 0.45 20 34 IC 30 69 MMI 98 47.4 9.9 TSH 0.07 0.43 34 33 IC 40 52 SCI 97 49.7 9.4 TSH 0.14 0.19 21 18 IC 46 63 SCI 67 31.6 4.0 TSH -7.99 0.84 24 31 ID 12 71 SCI 52 34.7 2.9 TSH -6.26 0.24 37 31 iD 29 106 SCI 77 59.3 6.1 TSH -0.08 0.13 35 38 ID 30 57 SCI 100 32 5.9 TSH -1.55 0.69 24 45 ID 32 89 SCI 100 31.7 5.5 TSH 0.05 0.36 25 24

51-5044435-00 Page 43 of 44 OD Circumferential Flaws Maximum Circumferential Plus Phase Depth Extent Elevation Point Angle Cal SGID Row Column Indication (%MW) (degrees) PDA Location (inches) Volts (degrees) Group lB 12 70 SCI 66 25.1 2.4 TSH -0 0.11 118 44 lB 12 71 SCI 88 41.9 2.4 TSH -0.06 0.24 54 44 IC 12 61 SCI 98 48.6 9.8 TSH 0.01 0.13 78 37 IC 16 59 SCI 96 41.3 6.5 TSH 0.01 0.27 76 54 IC 20 56 SCI 59 32.8 1.3 TSH 0.05 0.23 108 51 ID 12 67 SCI 74 49.1 4.5 TSH 0.07 0.14 78 31 ID 13 44 SCI 89 32.7 2.0 TSH 0.51 0.11 89 46 ID 16 51 SCI 0 64.8 0 TSH -0.04 0.25 98 49 ID 16 59 MCI 83 60.7 2.6 TSH -0 0.24 76 49

51-5044435-00 Page 44 of 44 Wear Indications 40% TW and Greater Maximum Depth Elevation Bobbin Cal SG iD Row Column Indication (%/olTW) Location (inches) Volts Group 1B 37 76 TWD 41 AV3 0.07 2.72 77 1B 40 64 TWD 40 AV3 -0.25 2.42 78 1B 40 83 TWD 48 AV5 0 4.13 76 1B 40 83 TWD 49 AV4 0 4.52 76 IB 42 24 TWD 40 AV4 0 2.49 55 1B 47 45 TWD 41 AV4 0.14 2.69 59 1B 47 45 TWD 43 AV3 0.02 2.92 59 lB 47 59 lWD 48 AV4 0.09 4.24 61 18 47 59 lTWD 40 AV3 0.09 2.37 61 1B 48 98 TWD 41 AV4 0 2.6 .89 1B 48 98 lTWD 42 AV3 0 2.74 89 lB 50 86 lTWD 42 AV5 0.14 2.74 83 1B 50 86 TWD 40 AV4 0 2.46 83 1B 54 61 TWD 45 AV2 0.07 3.44 80 1C 28 8 TWD 43 AVI 0.2 2.99 109 IC 34 15 TWD 43 AV2 0.16 2.97 109 1C 40 100 TWD 42 AV5 0.02 2.75 82 IC 44 71 TWD 41 AV5 0.11 2.69 85 1C 44 71 TWD 41 AV4 -0.02 2.63 85 IC 47 87 TD 45 AV5 0.24 3.27 84 1C 47 93 TWD 46 AV5 0.39 3.79 81

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