ML070590666

IR 0553792-02, Drywell Structural Integrity Basis from 1R21 Inspections (Final)

ML070590666
Person / Time
Site:	Oyster Creek
Issue date:	11/06/2006
From:	Tamburro P AmerGen Energy Co
To:	Office of Nuclear Reactor Regulation
References
Download: ML070590666 (39)

Text

3 IR 0553792-02, Drywell Structural Integrity Basis from 1R2'1 Inspections I

Reasons for EvaluatiodScope The purpose of this Technical Evaluation is to present current and projected (until 1R22) margin in Drywell Vessel Thicknesses and the bases to further confii that the drywell structwql integrity continues to maintain design basis requirements as established in references 1 through 3. Thle,

intent of this evaluation is to demonstrate that the Drywell Vessel thicknesses are adequate to 1

satisfy current licensing and design bases requirements.

This Technical Evaluation was developed in accordance with CC-k4-309-101, Revision 7,'

A prejob brief for this Technical Evaluation was performed by Howie Ray in accordance with Hu-AA-1212 Rev 1. The risk rank of this Technical Evaluation was concluded to be a "4"' since the acceptance criteria have already heen established and approved through existing desim analysis.

Therefore a third party review is not required.

Background

In the 1R21 Outage a series of UT thickness measurements were performed of various elevations of the Drywell Vessel in accordance with specification OC-IS -328277-004. The purpose of these UT inspections is to measure corrosion rates of the Drywell Vessel and further confirm that the vessel meets the design basis.

This is accomplished by inspecting the same locations over time.

In the mid 1980's a survey was performed of the Drywell Vessel at the Sandbed elevation (1 1' 3").

As a minimum at least one inspection location (also referred to as a grid) was selected the 10 Drywell Bays and permanently marked. These were then selected for repeat inspection and entered into the Drywell Thickness Monitoring Program.

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each of UT Inspection of locations with the most thinning consisted of obtaining 49 individual UT thickness readings in a 7 by 7 pattern spaced on 1 inch centers. These measurements were taken using a stainless steel template. The template was designed to ensure that the 7 by 7 grid is located in the same area with repeatability of a 1/16".

The program then performed UT inspections over time at these same locations from 1987 to 1996.

The corrosion rates were developed using a standard regression analysis and establishment of the 95% confidence intervals to capture increasing variance depending on the projection of ongoing corrosion and the number of inspections. This methodology is based on the following references:

1) Applied Regression Analysis, Second Edition, N.R. Draper & H. Smith, John Wiley and Sons 1981

2) Statistical Concept and Methods, G.K. Bhattacharyya & R.A. Johnson, John Wiley and Sons 1977, IR 553792 Assignment 02 1

e

3) Experimental Statistics, Mary Gobbons Natrella, John Wiley and Sons 1966 (Reprint

4) Fundamental Concepts in the Design of Experiments, Charles C Hicks, Saunders College National Bureau of Standards Handbook 91)

Publishing, Fort Worth, 1982 Each time UT inspections are performed the distribution of the individual readings is checked to contirm the original distribution evaluation.

Inspections of the Drywell above the sandbed have been performed up to 2006. Corrosion rates have been calculated in calculation C-1302-187-E3 10-037 Revision 2 and ECR 05-00575.

Corrosion in the sand bed region was addressed by removing sand, water, and corrosion byproduct in the sandbed and applying a coating on the exterior of the vessel in 1992.

Comparison of UT inspections performed in 1992 and 1994 as documented in C-1302-187-5300-030 shows that the sandbed region continues to meet design basis requirements.

This Technical Evaluation will compare the 2006 UT inspection data to these earlier calculations to further confirm conclusion that the drywell vessel continues to meet design basis.

Detailed Evaluation Methodology C-1302-187-E3 10-037 Revision 2 and C-1302-187-5300-030 identify the locations which are the most critical with respect to thinning (see table 1). These are located at five different elevations 11 3,50 2 51 lo, 60 10 and 87 5.

These calculations developed corrosion rate projections for these critical locations. The mean of the 2006 inspection of the same critical locations plotted on the earlier projections to determine if those projections are still valid and bound the current inspection results.

Elevation 11 3 Refer to the data in attachment 3 and the projection curve for location 19A in attachment 2.

Calculation C-1302-187-5300-030 identified location 19A as the most critical since it was the thinnest area in the sandbed. However the calculation conchded with 95% confidence that this location and the other sandbed region locations were not experiencing corrosion. Figure 1 provides a trend of the mean values for this location. Figure 1 also provides curves showing the calculated standard error of plus or minus 0.0034 inches for the means. The 2006 mean is also plotted on figure 1 and shows that this value is well within the standard error band.

Table 1 provides a breakdown of the mean thickness measured in 2006 and associated current margin.

IR 553792 Assignment 02 2

Elevation 50 2 8

Refer to the data in attachment 3 and the projection curves for locations 5-5 and 15-23 in attachment 2.

/

The 2004 calculation identified Iocations 5-5HI and 15-23HI as the most critical since they were the thinnest at this elevation. The calculation concluded that these locations ar;e experiencing corrosion rates of 0.0003 and 0.0004 inches per year with 95% confidence. Figure 2 and Figure 3 provide trends of the means of data collected from 1987 through 2004 for these locations taken from calculation C-1302-187-E3 10-037 Revision 2. The 2006,means for each location are plotted on these figures. These show that the 2006 means are consistent with and are bounded by the 2004 projections. Therefore the margins and projections from 2004 remain valid and bounding. Table 1 provides the means and margin calculated in 2004.

Table 1 provides a breakdown of the mean thickness measured in 2004 and associated current margin for these two locations.

Elevation 51 10 Refer to the data in attachment 3 and the projection curve for location 13-32 in attachment 2.

The 2004 calculation identified location 13-32 as the most critical since it was the thinnest at this elevation. However the calculation concluded with 95% confidence that the location was not experiencing corrosion. Figure 4 provides a trend of the means of data collected from 1987 through 2004 for this location taken from calculation C-1302-187-E310-037 Revision 2. The 2006 mean for this location is plotted on this figure. Figure 4 also provides curves showing the 2004 calculated standard error of -/+ 0.0053 inches for the data from 1987 to 2004. The 2006 mean is well within the 2004 standard error band.

This shows that the 2006 mean is consistent with and bounded by the 2004 projection, which concluded that this location is not corroding. Therefore the margin and projection from 2004 remains valid and bounding. Table 1 provides the means and margin calculated in 2004.

Table 1 provides a breakdown of the mean thickness measured in 2004 and associated current margin.

Elevation 60 10 Refer to the data in attachment 3 and the projection curve for location 5-22 in attachment 2.

The 2004 calculation identified location 5-22 as the most critical since it was the thinnest at this elevation. However the calculation concluded with 95% coni5dence that the location was not experiencing corrosion. Figure 5 provides a trend of the means of data collected from 1992 through 2004 for these locations taken from calculation C-1302-l87-E3 10-037 Revision 2. The IR 553792 Assignment 02 3

2006 mean for this location is plotted on this figure and shows that this value has virtually not changed since 2004.

Figure 4 also provides curves showing the 2004 calculated standard error of the data from 1987 to 2004. The 2006 mean is well within the 2004 standard error band.

Table 1 provides a breakdown of the mean thickness measured in 2004 and associatedcurrerit,

margin 8

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Elevation 87 5 Refer to the data in attachment 3 and the projection curve for location 9-20 in attachment 2.

The 2004 calculation identified location 9-20 as the most critical since it was the thinnest at this elevation. The calculation concluded that this location was experiencing a corrosion rate of 0.00075 inches per year with 95% confidence. Figure 6 provides the trend of the means of data collected from 1987 through 2004 for these locations taken from calculation C-1302-187-E3 10-037 Revision 2. The 2006 mean for this location is plotted on this figure. This shows that the 2006 mean is consistent with and is bounded by the 2004 projection. Therefore the margin and projection from 2004 remain valid and bounding. Table 1 provides the means and margin calculated in 2004.

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I Table 1 in attachment 1 provides a breakdown of the me& thickness measured in 2004 and associated current margin for these two locations.

Bay 15 Grid at Elevation 71 6 In 1R21 Oyster Creek performed first time inspections of two 6 by 6 areas above the transition weld at elevation 71 6. The results of the 6 by 6 area in bay 15 showed several local readings less than the inspection specification acceptance criteria (ref. 4). The intent of the criteria in the specification was to provide a low threshold for inspection results so that unexpected readings would be evaluated. As a result IR 00556049 was issued. Review of the inspection results showed that the thinnest local reading was 0.449 inches.

The inspection specification criteria were purposefully set well above the design basis criteria. The minimum required design basis local thickness for this elevation is 0.300 inches (reference 2).

Therefore the as found thickness at this Iocation meets the design basis requirements. In addition even when assuming a.001 inches per year corrosion rate, this location will continue to meet design basis until well past 2008. Comparison of this new location to an existing monitored location that has been determined to be the most critical for the plates at this elevation (location 9-

20) shows that the projections for the previously monitored location are bounding (refer to attachment 3 page 11).

Bay 17 Grid at Elevation 23 76 In 1R21 Oyster Creek performed first time inspections of two 6 by 6 areas above the transition weId at elevation 23 6. The results of the 6 by 6 area in bay 17 showed several local readings IR 553792 Assignment 02 4

less than the inspection specification acceptance criteria (ref. 4). The intent of the criteria in the specification was to provide a low threshoId for the inspection results so that unexpected readings would be evaluated. As a result IR 00548459 was issued. Review of the inspection results showed that the tliinnest local reading was 0.628 inches.

The inspection specification criteria were purposefully set well above the design basis criteria. The minimum required design basis local thickness for this elevation is 0.360 inches (reference 2).

Therefore the as found thickness at this location meets the design basis requirements. In addition even when assuming a.001 inches per year corrosion rate, this location will continue to meet design basis until well past 2008. Comparison of this new location to an existing monitored location that has been determined to be the most critical for the plates at this elevation (location 15-23) shows that the projections for the previously monitored location are bounding (refer to attachment 3 page 14).

Conclusions Table 1 demonstrates that current and projected margin in critical Drywell Vessel locations based on the comparison of recently obtained 2006 UT data and previously approved calculations remain adequate to continue to satisfy design bases requirements until 1R22. Compa'rison of the 2006 data to previously approved calculations, demonstrates that the conclusions in the previous calcuIations are still bounding the current data.

References

1) C-1302-187-E310-037 Revision 2

3) C-1302-187-5300-030 Revision 1

4) Specification IS-328227-004 Rev. 13

2) ECR 05-00575 Attachments

1) Margin Table - 1 page

2) Review of 2006 means value to previous projections - 6 pages

3) Drywell UT Inspection Data - 16 pages I

IR 553792 Assignment 02 5

Prepared by Pete Tamburro !J7&

//&/!O%

I have performed an independent technical review of this technical evaluation in accordance with Section 4!3 of CC-AA-309-101, Revision 7. I have confirmed the correctness of the inputs, mathematics, and outputs. I have verified the methodology and compliance with design bases criteria are appropriate. The results accomplish the stated purpose.

Independent Review By Frank Stulb Manager Comments:

Date: 11/06/06 This t&hnical evaluation was prepared and reviewed by qualified personnel to provide a summary of the lR21 Drywell Inspection results performed in 2006. The conclusions demonstrate that the structural integrity of the drywell shell, based on its measured thickness at representative locations, remains acceptable based on the previously approved methodologies and acceptance criteria.

I Approved for Use: Ray, F.H. 11/6/2006.

jz-/f%J$&

fl/QOb I

IR 553792 Assignment 02 6

Elevation/

Plate (Nominal Thickness Inches) 11 3 Percent (0.770) 50 2 (0.770) 51 10 (0.7 7 2) 60 10 (0.722) 87 5 (0.640)

Measured Corrosion Rate.

Inches/

year Summary of Oyster Creek Drywell Corrosion Monitoring Program Controlling Locations Measur ement (inches)

Location with Mean thinnest When 19A Bay 5 Location Bay 15 Location Bay 13 Location 32 Lo 5-HI 23-HI 0.8066 Bay 5 Location 22 10/2006 0.736 0.541 0.541 0.0706 0.2146 0.2 163 9.6%

0.5 18 C-1302-1 87-53 00-03 0 36.5%

36.4%

+

9.6%

C-1 302-1 87-E3 10-037 Rev 2

C-1 302-1 87-

.E3 10-037 Rev 2

39.7%

40%

10.0004 0.0003 I

32.7%

\\None 0.7556 0.7573 Preliminary Projected margin in 2029 based on 95%

confidence interval around the corrosion 10/2004 10/2004 Reference

- 2 33.6%

C-1 302-1 87-E3 10-037 Re\\

0.00075 I

Appendix 10

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System No.

Sheet No.

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11 of 15 AmerGen Calculation Sheet

Subject:

Calc. No.

Rev. No.

187 Drywell Corrosion C-1301-187-E31 O--

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v f

/

I MSR F actaul:==

a := 0.05 F critical := qF( 1 - a, DegreeFree reg, DegreeFree I - F actaul F critical F ratio *-

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F ratio = 1.7 15.1 0-3 Therefore the curve fit of the means does not have a slope and the grandmean is an accurate measure of the thickness at this location I

4 i :=O.. TotalmeanS-1 I

pgrand measuredi :=mean(p measured)

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.- ?grand measured

'grand measured := Stdev(p measured)

GrandStandad error,.- J=GZ The minimum required thickness at this elevation is Tminjen SB :=736 (Ref. Calc. SE-000243-002) i x x x Pgmnd measured 80' Tminsen SB

... "."_......I medown 780 Og meup -

760 740 Plot of the grand mean and the actual means over time I

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x 4

x"""' -.......-.......... "....................................

I..."..__

P I

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1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Dates

AmerGen Bay 5'Area 5

Subject:

Drywell Corrosion upperf := Thick predictf...

Calculation Sheet f

-~

Appendix 2 Calc. No.

System No.

Sheet No.

1 87 A2-27of 32 1

predictf' Thick actualmean)'.

sum lowerf := Thick predictf...

Yew predictf-Thick actualmean (d+ 1) sum General area Tmin for this elevation in the Drywell TminJen 51 :=541 f

(Ref. Calc. SE-000243-002) m = -0.246 lower 65C measured 0

Tmin-gen 5 1 00 60C 550 min(Tmin2en 51)-30 I

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2.029. I O3 1.985.103 Yew p r e d i c t - v p r e d i c t, F predict1 Dates *year predict. 2o06-8 I -

00J33751-~7

Calculation Sheet Appendix 4 CsnerGen Bay 15 Area 23

Subject:

~ I I A_-..--!--

d

/

Nn Rev. No.

System No.

Sheet No.

1 87 A4-28 Of 32 I

uryweii wxrosiuii

" I"".

I". --.- --.

For the thicker points L

Thick highpredict '0° 600 00 550 I'

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2005 2010 2015 2020 2025 2030 1985 1990 I995 2000 year predia,DatW.,year predict*ya predict*year

AmerGen Bay 13 Area 32

Subject:

Drywell Corrosion Calculation Sheet I //

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Calc. NO.

Rev. No.

I System No.

Sheet No.

C-l301-187-E310-037 A5 -24 Of 31 Appendix 5 Standard error 7oc 695 685 ag medown 675 670 I

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X x

X X

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990 I995 2000 2005 Dates I

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Standard error mean (. measured) ag medown :=Wand measured-m e m k measured) ag meup :=Wand measured+

72C 71C iJ measured xxx 7cK I G ~ '

measured ag medown Og meup 690 680 670 Appendix 6 Sheet No.

A6-12 Of 16 X

X X

X 4

1994 1996 1998 2000 2002 2004 2006 2008 Dates

~

Calculation Sheet Appendix 7 AmerGen Bay 9 Area 20

Subject:

Calc. No.

System No.

SheetNo.

Drywell Corrosion C-l301-187-E310-037 /

'187 A7-23 of 23 I

IS

'l'rnin_gen 86 := 452 -

(Ref,. Calc. SE-000243-002)

The minimum requi 650 65 60 m = -0.754 Location Curve Fit Projected to Plant End Of Life I

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I 422 I985 1990 1995 2000 2005 2010 2015 2020 2025 2030 3

Ye= predict, Year predict, Year 1 Year predict, 2o06*8 2030 1.985.10 3

year predictlz = 2.009*10 Thick predictlp = 604.1 15 Therefore the regression model shows that even at the lower 95% confidence band this location will not corrode to below Drywell Vessel Minimum required thickness by the plant end of life.

No Pits have been identified for this location Pose c 3 6 )

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Data Sheet A

B C

D E

F G

Thickness readings taken at holes 40 0 0 o o o o c 5

0 0 0 0 0 0 0 6

0 0 0 0 0 0 0 COMMENTS: File Specific Comments located to ngM of readings.

Location ID 11C: The following template holes were painted onto the plate using the template. The readings were then taken with the template removed. This was done due to the Drywell Vent Attachment weld obstructing the template. Row 1 A through G, Row 2 A through C, Row 7 C through D.

I at CO4, C05,804,805.

Reviewed by: Lee Stone Level II Date I

0/18/2006 t

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Data Sheet 0

I 3.(m t44*-744&

I Examined by Matt Wilson Level II Date 10/18/2006 1 Oli 8/2006 Reviewed by: Lee Stone Level I1 Date 1 0/18/2006 Examined by Leslie Richter Level II Date I

+.(ut

/o 20 -06 Examined by Matt Wilson Level II Date 1 0/18/2006 1 0/18/2006 Reviewed by: Lee Ston Level II Date

. I 0/18/2008 Examined by Leslie Ric Level II Date

Template aligned to V Stamps. I Thickness readings taken at holes located in template.

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I A

B C

D E

F G

1 ~ 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 70 o o o o o o 5 0 0 0 0 0 0 0

~ 0 0 0 0 0 0 0 R

I OMMENTS: Upper Elevation fnspection Location 9/20 (86-20)

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&gz /o*ZY-db Reviewed by: Lee Stone Level II Date 10/23/2006

NIA File Name:

Ultrasonic Thickness Measurement' Date:

10/1812006

enera1 Electric

)yster Creek UT P ~ o Q ~ u w ER-AA-3350M I

Specification:

18328227-004 tefueling Outage - 11R21 Data Sheet Page 5 of 15 I

Locatlon ID 13C 1 Bay I 13 I Elev. I 11'3" I Calibration Check: 13:48 6

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1 D

I E

l F

0 I N 11.146 1.148 I 1.1443 I 1.149 1 1.144 I 1.128 I 1.134 Tscr.

I AVO.

v

.628 I

1.142 1

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Locatlon ID i 5A Bay I 16 Elev. I Calibration Check: i4:W B

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D 1 E F

I G

I I A" 1

I 1.j80 1.129 I 1.136 1.129 I 1.146 1.077 I 1.049 iscr.

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AVO.

.628 I 1*$2' I

I Examined by Matt Wilson Level II Date 1011 8R006 Examined by Leslie Richter Level II Date 1011 8/2006 Reviewed by: Lee Stone Level II Date 10/18/2006

Ultrasonic Thickness Measurement nd below the minlmurn acceptance criteria, see page Reviewed by: Lee Stone Level I1 Date 10/23/2008 I

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1 q&&[

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l

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Date 10/23/2006 101~3/2006 10/23/2006 Level II Level II Date Level II Date Examined by Examined by Reviewed by:

D

1 3-53 7 p 2 - 0 '7 COMMENTS: File Specific Comments located to right of readings.

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AVO.

5 0.717

'0.700 0.718 0.716 0.717 I 0.716 0.679 0

0.711 0.712 0.720 0.719 0.718 I 0.719 0.681' T scr.

7 0.718 0.713 0.720 0.720 0.717 I 0.717 0.713

,676 I 0.699 I

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I Examined by Lee Stone L-Level II Date 1011 8MOO6 Reviewed by: Kimberly Wert &&A Examined by NIA Level N/A Date N/A A3 Level II Date 1 0/1 an006 U

AmerGen Bay 9 Area 20

Subject:

Drywell Corrosion Appendix 7 Calculation Sheet Calc. No.

Rev. No.

System No.

Sheet No.

I 1

.i 87 Ai'- 23 of 23 '

C-l301-187-E3l0-037 4

The minimum required thickness at this elevation is Tminsen 86 f :=452 Calc. SE-000243-002)

P C l t l w t

-T-I m s,= -0.754 Location Curve Fit Projected to Plant End Of Llfs I

650 650-60 626 500 I) 0 450 422 Therefore the regression model shows that even at the lower 95% confidence band this location will not corrode to below Drywell Vessel Minimum required thickness by the plant end of life.

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I No Pits have been identified for this' location

Ultrasonic Thickness Me a s uremen t Data Sheet Forty nine (49) readings were taken using the 8"x 8" template to determine the average reading.

A 100% scan within the 8 3 8" area to betermine the mjnimum and the maximum thickness.

A scan of the uppermost 1 " of horizonal weld was performed, the minimum reading on the weld was 0.700" the maximum reading on the weld was 0.893". Unable to obtain readings on the lower part of weld due to rough and non-parallel surfaces.

spection area centered 13" right of vertical seam weld between plate 71-1 and plate 71-2, looking outward. Reference wing 2E-187-29-001 RO.

9m'&C L G?

10 - z7-occ I Reviewed by: L e e Stone L5z-Level II Date 1012612006 I

Blodc Number:

CALSTEP-123 Calibration Check8 Final Cat. Time internal UT Inspectlorn Gaim Damping:

i NIA 71' 6" Weld Scan I

I Weld A

B C

D E

F O

1000 0 0 0 0 2 0 0 0 0 0 0 2.428"

[COMMENTS:

I Damping:

4 NrA

'N/A -

71' 6" Weld Sun Reject Fihk NrA 5

0 0 0 0 0 0 0 6

0 0 0 0 0 0 A scan of the uppermost 1" of horizonal weld was performed, the minimum reading on the weld was 0.717" the maximum pect'on area centered 4" left of vertical seam weld between plate 71-2 and plate 71-3, looking outward. Reference wing 2E-187-29-001 RO.

ading on the weld was 0.91 1". Unable to obtain readings on the lower part of weld due to rough and non-parallel surfaces.

3cIN 'dd.2 1 L lz /@-J7-OG 1012612006 I

AmerGen Calculation Sheet Appendlx 4 Bay 15 Area 23

Subject:

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Calc. No.

Rev. No.

System No.

Sheet No.

Drywell Corroslon C-1301-187-E310-037 1

1'87 A4-27of 32 D

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General area Tmin for this elevation in the Drywell I

Tminsen 51 f :=541 (Ref. Calc. SE-000243-002)

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I COMMENTS:

Forty nine (49) readings were taken using the 8% 8" template to determine the average reading.

100% scan of the weld and 100% scan within the 8"x 8" area to determine the minimum and the maximum thickness.

Minimum reading on weld was 0.689", Maximum reading on weld was 0.91 8".

1 mspection area centered 55" lefl of vertical seam weld between plate 23-19 and plate 23-20, looking outward. Reference drawing 2E-187-29-001 RO.

W M W I d f l /b - 2 S 4 6 Date 10/23/2006 Reviewed by: Lee Stone Level II

3 0

0 0 0 0 0 0 COMMENTS:

Forty nine (49) readings'were taken using the 8% 8" template to determine the average reading.

100% Scan ofthe weld and 100% scan within the 8% 8" area to determine'the minimum and the m q h u m thickness.

Minimum reading on weid was 0.865", Maximum reading on weld was 1.029" nspection area centered 15" left of vertical seam weld between plate 23-18 and plate 23-19, looking outward. Reference L M n g 2E-187-29-001 RO.

Date 1 OD4I2008 Reviewed by: Lee Stone Level II I

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$qHf / & p - O b 1011 8/2006 1011 8/2006 10/18/2008 Date Date Date Examined by Matt Wilson Level II Examined by Leslie Richter Level II Reviewed by: Lee StOM Level II

i P 2 I l R - 026 py /OF 2 Template aligned to V Stamps.

Thickness readings taken at holes located in template.

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I A

B C

D E

F G

1orooo 0 0 0 0 0 0 0 0 0 0 0 40 o o o o o o 6

0 0 0 0 0 0 0 7 0 o o o o o o 5

0 0 0 0 0 0 0

+

a

?

COMMENTS:

Readings found below the minimum acceptance criteria, see page 2 (50 - 22).

L S

cwM '&(

i&-zJ-d6 Reviewed by: Lee Stone Level II Date 10/23/2008

B Level I1 Date 10/23/2006 10/23/2006 10/23/2006 Examined by Examined by Reviewed by:

Level If Date Level II Date

Ultrasonic Thickness Measurement Data Sheet I

Template aligned to V Stamps.,

I Thickness readings taken at holes located in template.

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V I

r 1

I

~1oyooo A

B C

D E

F G

0 0 0 gs taken on Cora Plug.

COMMENTS: File Specific Comments located to right of readings.

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&>&TL-rr L LL r wd&&/-

i o 20 *'6 Reviewed by: Kimberly Wed k

h Level II Date 1011 8/2008 U

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w+p /o -ma 1011 8/2006 1011 8/2006 Level I1 Date Examined by Lee Stone Examined by NIA Level NIA Reviewed by: Kimberly Wert Ad-Level ll Date Date NIA U

~

Calculation Sheet Appendix 7 AmerGen

)I Sheet No.

I Calc. No.

Rev. No.

System No.

C-l301-187-E310-037 1

i 87 A7-23 of 23 Bay 9 Area 20 Drywell Corrosion

Subject:

I I

The minimum required thickness at this elevation is Tminsen 86 :=452 (Ref: Calc. SE-000243-002) f P

C W

ctf I.

Location Curve Fit Projected to Plant End Of Life ms,=

-0.754 I

-v 1 1 65C

650, 600 50 626 500 0

450 422 I

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I Therefore the regression model shows that even at the lower 95% confidence band this location will not corrode to below Drywell Vessel Minimum required thickness by the plant end of life.

No Pits have been identified for this. location

4 u.

\\

2 Data Sheet 0 0 0 0 0

'Forty nine (49) readings were taken using the 8"x 8" template to determine the average reading.

A 100% scan within the 8"x 8" area to determine the minimum and the maximum thickness.

A scan of the uppermost 1" of horizonal weld was performed, the minimum reading on the weld was 0.700" the maximum reading on the weld was 0.893". Unable to obtain readings on the lower part of weld due to rough and non-parallel surfaces.

spection area centered 13" right of vertical seam weld between plate 71-1 and plate 71-2, looking outward. Reference wing 2E-187-29-001 RO.

M W ' A C L GT IO - z 7 - o ( L Level II Date 10/26/2006

Y Ultrasonic Thickness Measurement 5

0 0 0 0 0 0 0 6 0 0 0 0 0 0 0 7 0 0 0 0 0 I

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AmerGen Bay 15 Area 23

Subject:

Drywell Corrosion Appendix 4 Calculation Sheet Calc. No.

Rev. No.

System No.

Sheet No.

C-1301-187-E310-037 1

187 A4-27 Of 32 I '

For the overall mean upper, := Thick prdictf...

I 2

(year predict,- n i c k qctualmean)

S U m

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1 I

1 L

t I

I 8

I General area Tmin for this elevation in the Drywell I

Tminsen 5 1 := 541 (Ref. Calc. SE-000243-002) f m = -0.777 750 550 I

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I 8

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4 I

I

0 0'0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O O Q O Max. 1.I 99" c

Area 114" to 3i8" along weld toe below.960" COMMENTS:

Forty nine (49) readings were taken using the 8% 8" template to determine the average reading.

100% scan of the weld and 100% scan within the 8"x 8" area to determine the minimum and the maximum thickness.

Minimum reading on weld was 0.689", Maximum reading on weld was 0.91 8".

nspection area centered 55" left Of vertical seam weld between plate 23-1 9 and plate 23-20, looking outward. Reference drawing 2E-187-29-001 RO.

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I 10/23/2008 Reviewed by: Lee Stone Level I1 Date

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7. 0 0 0 0 0 O 0 2-I Max.1.186" I

Avg.

COMMENTS:

Forty nine (49) readings were taken using the 8% 8" template to determine the average reading.

100% scan of the weld and 100% scan within the 8% 8" area to determine the minimum and the maximum thickness.

Minimum reading on weld was 0.865", Maximum reading on weld was 1.029" area centered 15" left of vertical seam weld between plate 23-18 and plate 23-19, looking outward. Reference W7U&&dL.L. L z ? /o-25-06 awing 2E-187-29-001 RO.

1 10/24/2006 Reviewed by: Lee Stone Level II Date I

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