NL-06-0422, Evaluation of Main Steam Nozzle Indications

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Evaluation of Main Steam Nozzle Indications
ML060610658
Person / Time
Site: Hatch Southern Nuclear icon.png
Issue date: 03/01/2006
From: Sumner H
Southern Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-06-0422
Download: ML060610658 (37)
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Text

H. 1. Surnner, Jr. Southern Nuclear Vice President Operating Company, Inc.

Hatch Project Post Office Box 1295 Birmingham. Alabama 35201 March 1, 2006 Energy to Serve Your WorldU" Docket No.: 50-321 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 1 Evaluation of Main Steam Nozzle Indications Ladies and Gentlemen:

Two indications were identified during the 2006 1R22 in-service inspection of the Hatch Unit 1 reactor pressure vessel (RPV). The indications are in the weld between the vessel shell and the N3A main steam nozzle. Indication #1 is a subsurface indication with a depth of 0.67 inches, a length of 1.9 inches, and a surface separation of 2.57 inches. Indication #2 is a subsurface indication with a depth of 0.49 inches, a length of 1.40 inches, and a surface separation of 1.75 inches. The indications were found to be unacceptable per the rules of the ASME Boiler and Pressure Vessel Code,Section XI, 2001 Edition through the 2003 Addenda, paragraph IWE3-3510.

Consequently, analytical evaluation is required per the guidelines of Section XI, IWB-3610 to determine if the indications are acceptable for continued service. Based on the results of that analytical evaluation the indications are acceptable. The calculated total fatigue crack growth for 40 years of additional service life is 0.02 14 inches. The final crack size would be 0.69 14 inches for Indication # 1 and 0.5 114 inches for Indication

  1. 2 at the end of 40 years of additional service life.Section XI, IWB-3134(b) requires the analytical evaluation results be submitted to the regulatory authority having jurisdiction at the plant site (see attached analytical evaluation developed by Structural Integrity Associates).

Two teleconferences were held with NRC to discuss SNC plans with respect to the above mentioned evaluation and potential scope expansion. One was held on February 24,2006 and the second on February 28,2006.

SNC's planned actions are discussed below.

Scope Expansion ASME Section XI, 2001 Edition through the 2003 Addenda, paragraph IWB-2430 requires that even though the indications have been determined to be acceptable for continued operation, examination of additional nozzles equivalent to the number of nozzles scheduled for the current period must be performed. In lieu of this requirement, alternate requirements are provided in Code Case N-586, which allows an engineering

U. S. Nuclear Regulatory Commission NL-06-0422 Page 2 evaluation to be performed to determine the need for the additional examinations. Code Case N-586 requires the engineering evaluation to include: (1) a determination of the root cause of the flaws or relevant condition, and (2) an evaluation of applicable service conditions and degradation mechanisms to establish that the affected welds will perform their intended safety functions during subsequent operation. No additional examinations are required if the engineering evaluation concludes that either: (1) there are no additional welds subject to the same root cause conditions, or (2) no active degradation mechanism exists.

Root Cause - The most likely root cause of these indications is weld porosity andlor slag inclusions associated with original fabrication of the main steam nozzle to shell weld. As such, these indications have probably been in existence since RPV fabrication. These indications were observed during the 1997 examinations and were determined to be acceptable in accordance with the Acceptance Standards in ASME Section XI, IWB-35 10. The 1997 examination data files were re-analyzed this outage utilizing the current Performance Demonstration Initiative (PDI) techniques/equipment and compared to the 2006 results. It was determined that the thru-wall depth and length measurements between the 1997 and 2006 data using the PDI methodology are similar; therefore, the reason for the indications now being unacceptable is due to the use of more precise PDI techniques. PDI qualified examinations have been completed for 14 other nozzles that were scheduled for this outage, without any additional unacceptable indications.

Degradation Mechanism - These subsurface flaws were evaluated for corrosion related degradation and mechanical failure degradation. Other than fatigue, it was determined that there are no active degradation mechanisms. The effect of fatigue was evaluated in the attached analytical evaluation and was found to have an insignificant effect on the flaws. Therefore, it is concluded there are no active degradation mechanisms that could prevent the vessel from performing its intended function. Without the presence of active degradation mechanisms, no additional weld examinations are required by Code Case N-586.

Successive Examinations ASME Section XI, 2001 Edition through the 2003 Addenda, paragraph IWB-3132.3 requires that indications that exceed the acceptance standards of Table IWB-35 10-1, that are found acceptable for continued operation by IWB-3600, must subsequently be reexamined during the next three periods in accordance with IWB-2420(b). ASME Section XI, Code Case N-526 provides alternate requirements for re-examination of subsurface flaws found by volumetric examinations in lieu of the IWB-2420(b) requirements. Code Case N-526 states that the reexaminations in accordance with IWB-2420(b) of vessel volumes containing subsurface flaws are not required, provided the following are met:

a. The flaws are characterized as subsurface in accordance with the figure provided in the Code Case.
b. The NDE technique and evaluation that detected and characterized the flaw, with respect to both sizing and location, shall be documented in the flaw evaluation report.

U. S. Nuclear Regulatory Commission NL-06-0422 Page 3

c. The vessel containing the flaw is acceptable for continued service in accordance with IWB-3600, and the flaw is demonstrated acceptable for the intended service life of the vessel.

The largest crack depth of the two indications is Indication #1 with a flaw depth of 0.67 inches. Therefore, the Flaw Half Depth for Indication #1 is 0.335 inches. Using Figure 1 of Code Case N-526, for a Flaw Half Depth of 0.335 inches, the minimum distance from the surface to be classified as a subsurface flaw is 0.25 inches. Both indications are at a greater distance from the surface than this and therefore can be .

classified as subsurface indications. As such, provision.(a) in the Code Case above is met. Provision (b) of the Code Case is satisfied since the NDE techniques used to detect and size the flaw is documented and accepted by the industry (PDI qualified examination). Provision (c) of the Code Case is also satisfied since an IWB-3600 evaluation has been performed to show acceptability of the flaw for the balance of plant life. Therefore, IWB-3 132.3 re-examination is not required. These flaws will be re-examined in the next 10 year interval pursuant to IWB-2500.

Sincerely.

H. L. Sumner, Jr.

Enclosure:

Structural Integrity Associates; Evaluation of Weld N3A (N-SH) at Hatch Unit 1 During 2006 Outage (1R22) cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, General Manager - Plant Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatorv Commission Dr. W. D. Travers, Regional Administrator Mr. C. Gratton, NRR Project Manager - Hatch Mr. D. S. Simpkins, Senior Resident Inspector - Hatch

Enclosure Edwin I. Hatch Nuclear Plant - Unit 1 Evaluation of Main Steam Nozzle Indications Structural Integrity Associates; Evaluation of Weld N3A (N-SH) at Hatch Unit 1 During 2006 Outage (1R22)

Revision Description 1 INTRODUCTION Two indications were identified during the 2006 Refueling Outage R22 in-service inspection of the reactor pressure vessel (RPV) of Hatch Unit 1. These indications are in the weld between the vessel shell and the main steam nozzle, N3A. The indications were found unacceptable per the rules of the ASME Boiler and F'ressure Vessel (B&PV) Code,Section XI, 2001 Edition and Addenda through 2003, IWB-3510, [I].

Consequently, the indications are evaluated per the guidelines of ASME B&PV Code,Section XI, TWB-3610, which include acceptance criteria based on the applied stress intensity factors. Conservative assumptions in the applied stresses were used in this evaluation to determine the stress intensity factors for the two indications for comparison to the Code allowable stress intensity factor.

2 TECHNICAL APPROACH The original RPV stress report [2] was performed in accordance with the requirement of ASME B&PV Code, 1965 Edition with Addenda through Winter of 1966. The pages containing the stress analysis results of the main steam nozzle are not available in Reference 2. Conservative applied stresses were assumed using the ASME B&PV Code Section I11 allowable stress for the RPV material.

The stress intensity factor was calculated based on Reference 1, Appendix A methodology. The flaw acceptance criteria based on applied stress intensity was utilized based on Paragraph IWB-3612 of Reference 1.

3 FLAW CHARACTERIZATION The two indications are planar indications located in the weld, Weld ID N3A (N-SH), between the vessel shell and the main steam nozzle, N3A [3]. The inspection results for the indications are shown in Figures 1 and 2. For Indication 001, Figure 1 shows that it is a subsurface indication with a depth of 0.67 inches, a length of 1.9 inches, and a surface separation of 2.57 inches. Indication 002, Figure 2, is 0.49 inches in depth, 1.40 inches in length, and 1.75 inches in surface separation.

4 DESIGN INPUTS From Reference 2, the nominal wall thickness is 5.375 inches for the Main Steam to RPV Weld N3A (N-SH). The measured thickness is 5.88 inches, [Z]. For this evaluation, the nominal wall thickness was conservatively used. The inside diameter is 220.75 inches, [2].

The reactor vessel material is ASTM A533 B-1, from Reference 2.

From Reference 2, the allowable stress S, is 26.7 ksi at 575 OF, the design temperature [2], for ASTM A533 B-1. The yield stress for ASTM A533 B-1 is 43.98 ksi at 575 OF, per Reference 4.

File No.: HTCH-13Q-301 Revision: 0 Structural Integrity Associates, Inc. Page 2 of 14

5 ASSUMPTIONS Since stress information in the Stress Report at the flaw location is not sufficiently detailed, the applied stress was assumed to be at the Code allowable stress at 575 OF, the design temperature, as shown in Table 1, per References 2 and 4. In particular, the membrane stress was assumed to be at l.OS,, and the through-wall bending stress was assumed to be at 2 S,. This assumption is based on the Code stress limits for the Normal and Upset Conditions, where P, c S, and Pl+Pb+Qc 3Sm. Typical primary and secondary stresses in the reactor vessel are about 25 ksi. Therefore, assuming the applied stress at the Code allowable limit should be bounding the vessel stress.

For Emergency and Faulted conditions, the applied stresses were also assumed to be at the Code stress allowable, as shown in Table 1.

In addition, an 8 ksi cosine shape through wall residual stress was assumed based on References 5 and 6, and added lo the membrane and bending stresses. The residual stress is assumed to be pure bending through the reactor vessel wall. This assumption is conservative based on the location of the indications and the residual stress profile specified in Reference 6.

As in the original stress report, the clad thickness is not considered in this evaluation.

The service life is assumed to be 40 years from the date of this evaluation.

6 CALCULATIONS 6.1 Stress Intensity Factor Calculation A linear elastic fracture mechanics and crack growth evaluation is performed for the indications. Each indication was modeled as a subsurface semi-elliptical crack in an infinite plate subjected to membrane and bending stresses as illustrated in Figure 3, Reference 1. For this subsurface crack model, the flaw depth is defined as 2a, as shown in Figure 3. Therefore, the crack depth, a, is half of the measured crack depth as reported in Figures 1 and 2.

Using the assumption for applied stress as presented in Section 5, for S, = 26.7 ksi, the membrane stress is 26.7 ksi and the bending stress is 53.4 ksi.

For Indication 001, the crack parameters were calculated as follows:

Crack depth 2a = 0.67 inch Crack length 1= 1.9 inches Crack aspect ratio: all = 0.1763 Eccentricity e = 2.57 + 0.67/2 - 5.37512 = 0.2175 Eccentricity ratio: W t = 2*0.217515.375 = 0.0809 For Indication 002, the crack parameters were calculated as follows:

File No.: HTCH-13Q-301 Revision: 0 Structural Integrity Associates, Inc. Page 3 of 14

Crack depth 2a = 0.49 inch Crack length 1 = 1.4 inches Crack aspect ratio an = 0.175 Eccentricity e = 5.3792 - (1.57 + 0.49/2) = 0.8725 Eccentricity 2dt = 2

  • 0.872Y5.375 = 0.3247 The applied stress intensity factors for the tGo indications above were calculated using pc-CRACK. [7].

The minimum crack aspect ratio of 0.1 was conservatively used in the evaluation for both indications.

6.2 End of Life Fatigue Crack Growth Calculation Since the indications are subsurface, the end of life flaw size due to crack growth was calculated using the fatigue crack growth curves for carbon and low alloy ferritic steels exposed to air environments, Figure A-4300-1 of Appendix A of Reference 1:

da/dN = C,(AKI)" (idcycle) (1) n = 3.07 C, = 1.99x10-'~~

S = 25.72*(2.88-R)-~" for OS5l R = Kmi"/K,,

AK1= K, - Kh, (ksidin) 6.3 Material Fracture Toughness Calculation The material fracture toughness of the weld metal is provided in References 8 and 9 for weld metal SA-316. The lowest Charpy V notch impacts energy 110 ft-lb.

From Reference 4, the material fracture toughness Klc can be calculated from the Charpy impact energy using the following equations:

J = 10CVN (2)

J=1000*~l~~/~' (3)

Substituting (2) into (3) and rearranging:

KlC = i";"w'" (4) where CVN = Charpy energy in ft-lb J = material toughness E' = ~ ( 1 - v 2 )

E = Young's Modulus (ksi)

File No.: WCH- 13Q-301 Revision: 0 Structural Integrity Clssociates, Inc. Page 4 of 14

7 RESULTS OF ANALYSIS 7.1 Stress Intensity Factor Using the proximity rule in WA-3300 of Reference 1, the indications are shown to be subsurface and do not require to be considered as a single flaw. For Indication 001, the surface separation, S, is 2.57 inches which is larger than half of the crack depth, 0.335 inch. For Indication 002, the surface separation is 1.75 inches which is larger than half of the crack depth 0.245 inches. The angle between the two indications is 13.9". Using the inside diameter, the distance between the two indication is 220.75*~*13.9/360= 26.78 inches which is larger than the length of either indication. Therefore, these two indications do not have to be considered as a single flaw.

The applied stress intensity factors, using the subsurface crack model for the two indications, are presented in Figure 4. It is shown that, at the inspected crack depths, the applied stress intensity factor, Kapplied,is 40 ksidin for Indication 001 and 47 ksidin for Indication 002 for the Normal and Upset Conditions.

For the Emergency Condition, the Kapplicd is 54 ksidin for Indication 001 and 52 kidin for Indication 002.

For the Faulted Condition, the is 68 ksidin for Indication 001 and 65 ksidin for Indication 002 The pc-CRACK output files for the stress intensity factor calculation are listed in Appendix A.

Using Equation 4, with E = 26.55~10~ ksi at 575 OF [4], the Kc is calculated to be Klc = d(l 10*26.55x103/(1-0.32)/100)= 179 ksidin For the Normal and Upset conditions, using a safety factor of 410, per IWB-3612, Reference 1, the allowable fracture toughness is 179/610 = 56.61 ksidin, which is higher than the applied stress factor (40 ksidin and 47 ksidin) for both indications.

For the Emergency and Faulted conditions, using a safety factor of 42, per IWB-3612 of Reference 1, the allowable fracture toughness is 179/d2 = 126.57 ksidin, which is higher than the applied stress intensity factors for both indications (54 ksidin and 68 ksidin for Indication 001 and 52 ksidin and 65 ksidin Indication 002).

7.2 Crack Growth Conservatively assuming that the stress intensity factor is cycled from zero to positive Kappticd, for the fatigue crack growth calculation, using Equation I, with R= Kmin/K,, = 0 and AKI= 46.49 ksidin (maximum between Indications 001 and 002), gives S = 25.72*(2.88-(0))".07 = 0.999 Co = 1.99x10-'~*~ = 1.99~

WdN = 1.99~10.'~*(47)~.~~ = 2.62x10-' in/cycle File No.: HTCH-13Q-301 Revision: 0 Structural lntegriity Associates, Inc. Page 5 of 14

From Reference 2, the significant transients are shown in Table 2. The total number of significant transients is 409 for a design life of 40 years. These cycles are used as 40 years from the date of this evaluation. All these transients are assumed to cycle from 0 to 47 ksidin . Therefore, the total crack growth at the end of the vessel service life is 2*2.62x10-409 = 0.0214 inch, accounting for the crack growth at both end of the subsurface crack. This amount of crack growth is insignificant compared to the initial crack size. The final crack size at the end of vessel service life is 2a = 0.67+ 0.0214 =0.6914 inch for Indication 001, and 2a = 0.49 + 0.0214 = 0.51 14 inch for Indication 002. For this final crack size, as shown in Figure 1, the applied stress intensity factor is about 43 ksidin for Indication 001 and about 50 ksidin for Indication 002, less than the allowable Krc of 56.6 ksidin.

7.3 Successive Inspections As required by ASME Code Section XI IWB-3132.3, indications that exceed the acceptance standards of Table WB-3510-1 and found acceptable for continued operation by IWB-3600 must be subsequently re-examined in accordance with IWB-2420(b) and (c). IWB-2420(b) requires that the area containing the flaw shall be inspected during the next three inspection periods listed in the schedule of the inspection program of IWB-2400. ASME Section XI Code Case N-526 [lo] provides alternate requirements for re-examination of subsurface flaws found by volumetric examinations in lieu of the requirements in IWB-2420(b).

Code Case N-526 states that the re-examinations in accordance with IWB-2420(b) of vessel volumes containing subsurface flaws are not required, provided the following are met:

a) The flaws is characterized as subsurface in accordance with the figure provided in the Code Case (shown in Figure 5) b) The NDE technique and evaluation that detected and characterized the flaw, with respect to both sizing and location, shall be documented in the flaw evaluation report.

c) The vessel containing the flaw is acceptable for continued service in accordance with IWB-3600, and the flaw is demonstrated acceptable for the intended senice life of the vessel.

The largest crack depth of the two indications is Indication 001 with half crack depth of is 0.335 inches.

From Figure 5, the required minimum distance from surface for a flaw to be classified as a subsurface flaw is 0.25 inches. Both indications are at a distance from the surface greater than this and therefore can be classified as subsurface indications per Code Case N-526. As such provision (a) in the Code case as stated above is met. Provision (b) of the Code Case is also satisfied since the NDE technique used to detect and size the flaw is documented and accepted by the industry (PDI qualified examination). Provision (c) of the Code Cese is also satisfied in this calculation since an IWB-3600 evaluation has been performed to show acceptability of the flaw for balance of plant life.

From the above discussions, it has been demonstrated that subsequent re-examination in accordance with IWB-2420 (b) and (c) of the indications identified in Weld N3A (N-SH) are not required.

File No.: WCH-13Q-301 Revision: 0 Structua/ /nte~rity Associates, /nc. Page 6 of 14

8 CONCLUSIONS AND DISCUSSIONS Based on the results of the evaluation presented in this calculation package, the indications found during the inservice inspection of the RPV axial welds are acceptable and meet the requirement of ASME Code,Section XI, IWB-3610 [I]. For 'the Normal and Upset conditions, the maximum applied stress intensity factor calculated in this analysis is 47 ksidin. This applied stress intensity factor is well below the allowable material fracture toughness of 56.61 ksidin. The fatigue crack growth at the end of vessel service life is 0.0214 inch. The final crack depth at the end of vessel service life is 0.6914 inch and 0.51 14 inch for Indications 001 and 002, respectively. The applied stress intensity factor at the end of service life is still less than the allowable fracture toughness.

In addition, successive examinations as required by ASME Section XI, IWB-2420(b) and (c) are not required per ASME Section XI, Code Case N-526.

9 REFERENCES

1. ASME Boiler and Pressure Vessel Code,Section XI, 2001 Edition and Addenda through 2003.
2. Combustion Engineering Inc. 'Analytical Report for Hatch No. 1 Reactor Vessel,' Report No. CENC 1160, August, 1971, SI File GPCO-42Q-235P.
3. GE Nuclear Energy, UT Examination Summary Sheet, Summary No. G2K-1R22-011, February 23, 2006, SI File HTCH-134-201.
4. ASME Boiler and Pressure Vessel Code, Section 111, Appendices, 1998 Edition with Addenda through 1999.
5. EPRI TR- 100251, "White Paper on Reactor Vessel Integrity Requirements for Level A and B Conditions,' Electric Power Research Institute, January 1993.
6. EPRI Report, 'BWRVIP-60A: BWR Vessel and Intemals Project, Evaluation of Stress Corrosion Crack Growth in Low Alloy Steel Vessel Materials in BWR Environment," EPRI Technical Report 1008871, June 2003.
7. pc-CRACK for Windows, Version 3.1-98348, Structural Integrity Associates, 1998.
8. ABBICombustion Engineering, Document #RVG-0000000322, Weld Material Certification Report, 7/13/94, SI File HTCH-134-202.
9. ABBICombustion Engineering, Document #RVG-0000000326, Weld Material Certification Report, 7/13/94, SI File HTCH- 13Q-202.
10. ASME, Boiler and Pressure Vessel Code, Code Case N-526, 1998 Edition.

File No.: HTCH-13Q-301 Revision: 0 Structural lntegriiy Associates, Inc. Page 7 of 14

Table 1: Stress Allowable at 575 OF for SA 533 Grade B Class 1 Stress Design and upset Emergency Condition Faulted Condition Categories Condition Greater of Lesser of sm 1.2 Sm (32.04 ksi) 2.4 Sm(64.08 ksi) and pm (26.7 hi) --

and S, (43.98 ksi) 0.7 S, (56 h i )

1.5 S, Greater of 1.5 P",

PI+~c (40.05 ksi) -- 1.8 S, (48.06 h i ) (84 ksi) and 1.5S, (65.97 ksi)

Pl+Pb+Pc+Q -- 3sm -- --

(80.1 ksi)

Note: Sm= Code allowable stress intensity, 26.7ksi S, = yield strength, 43.98 ksi S, = ultimate tensile strength, 80 h i The ultimate tensile strength was obtained from 1974 Edition of B&PV Code.

File No.: HTCH-13Q-301 Revision: 0 Structural Inteflrity Associates, / n ~ . Page 8 of 14

Table 2: Significant Transient Conditions Transient Condition Occumnces Normal Start Up 120 Loss of Feedwater Heaters - Turbine Trip at 25% Power 10 Loss of Feedwater Heaters - Feedwater Heater Bypass 70 Loss of Feedwater Pump 10 Turbine Generator Trip 40 Safety Valve Blowdown 2 All Other Scrams 147 Improper Start of Cold Recirc. Loop 5 Sudden Start of Cold Recirc. Loop 5 Total 409 File No.: HTCH-13Q-301 Revision: 0 Structural Integrity Associafes, Inc. Page 9 of 14

Reacfw Pnessure Vessel Flaw EvaluaSlon Sheet I

1 Figure 1 Summary No. G2K-1R22-011,Indication #1Data File No.: HTCH-13Q-301 Revision: 0 Structural IntegrifV Associates, I ~ c . Page 10 of 14

- Reactor Pres-surer Vessel

@ e ~ e f i ~ ~ r - ~ u uRaw Eva!ua#on Sheet mjoct: PbPrrliUrrlt/Ye#

W M t D :NSYN-SH) E x ~hlt e SbPt : N3A{N-SM)-Ol lCldieoi3on r 002 S&ng Dolba Sheet : N?IA40I

~ R o w l C k d a l w w s f l m

' RowT)HouLlhWeM= 0.48 06 'Tnomlnsl* 6.88 5-P f l 8 w L ~ g U I *re 1-40 1.4 'r"maasumd= 6.88 6.Q

~&11f8ooStpMiHan~S~=1.76 1.8 ASME Swth N,1- EdIUon, bla Addenda TABLE IBNB4590-4 IbrFtb 72' aA 0.00 8wtsceW 1.0 tlrkrur*a%

20 --

S~~IGco%Guburl#r#

0.08 RlO 20 22 2.2 2.6 -

0.16 U20 2.6 2.8 3.3 29 3.3 -

2.67 3.43 Y a25 3.4 "

O m 3'0 4.4 .

035 4.4 6.t 4

0.0 6.0 M c OM 6.1 R7 0.60 62 7-6 4. 4.

Albwad m d 2 , 3.13 1 8' om envaluo= 0.77Q vu 1.000 Flaw Is Subswbm AlbwedW= 3.1%

Pan* 4.2%

lever: =?!2~ eta: z-aa-a6 L ~ I : $6 D*.: i a ~ ~ ~ p Want?W I Y W ~cle.

a...Qof&/?

4t.ttdb Figure 2: Summary G2K-1R22-011, Indication #2 Data File No.: HTCH-13Q-301 Revision: 0 SfructuraI Integrity Associates, Inc. Page 11 of 14

I Calculated K i s maximum ofK at points 1 & 2.

Model aisumesthat the center of the cwck P is positioned at x 5 tl2 Co" %+%

c1 = '2ubit ~ectiokA-A

% = Co + C1(%J (membrane stress) 4 = -C lfi2)@ ending stress)

REQUIRED INPUTS:

t: wall thickness a: maximumcwck depth (h, 5 min[(O. 95 - 2dt>tl2,0.325t])

q- material yidd stress dQ:uackaspectratio(O.1 IdQSD.5) 2dt: eccenhicityratio (0 I2dt 5 0.6)

Figure 3 ASME B&PV Code Section XI Subsurface Crack Model File No.:HTCH-13Q-301 Revision: 0 Structural lnteflriiy Associates, Inc. Page 12 of 14

250 200 150 2<

--C

  1. )

X V

100 50 0

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1-6 1.8 2 Half Crack Depth (In)

Figure 4: Applied Stress Intensity Factor, Normal and Upset Conditions, Weld ID N3A(NSH)

File No.: HIGH-13Q-301 Revision: 0 Struetufa/ Inte~rity Associates, Inc. Page 13 of 14 I

Flaw Half Depm, a (in)

Figure 5: Successive Examination File No.: IFTCH- 13Q-301 Revision: 0 Structural Integrity Associates, Inc. Page 14 of 14 L

APPENDIX A pc-CRACK OUTPUT FILES File No.: HTCH-13Q-301 Revision: 0 Sfrucfural lnf8griW Associates, Inc. Page AI of ~ 1 9

pc-CRACK Output File for Weld N3A(N-SH) Indication 001, Normal and Upset Condition tm pc-CRACK for Windows Version 3.1-98348 (C) Copyright '84 - '98 Structural Integrity Associates, Inc.

3315 Almaden Expressway, Suite 24 San Jose, CA 95118-1557 Voice: 408-978-8200 Fax : 408-978-8964 E-mail: pccrack@structint.com Linear Elastic Fracture Mechanics Date: Fri Feb 24 09:47:41 2006 Input Data and Results File: IND001.LFM

Title:

HTCH-13Q, Weld N3A(N-SH), Indication #OOl Load Cases:

Stress Coefficients Case ID CO C1 C2 C3 Type Pm+ Pb 88.1 -22.85 0 0 Coeff

Through Wall Stresses for Load Cases With Stress Coeff-------

Wall Case Depth Pm+Pb 0.0000 88.1 0.1737 84.1312 0.3474 80 .I625 0.5211 76.1937 0.6947 72.225 0.8684 68.2562 1.0421 64.2874 1.2158 60.3187 1.3895 56.3499 1.5632 52.3812 1.7369 48.4124 Crack Model: Elliptical Subsurface Cracked Plate Under Membrane & Bending Stresses

Reference:

ASME Boiler and Pressure Vessel Code,Section XI, '86 Ed.

WARNING: The stress intensity factor (K) is the maximum of K at point 1 and K at point 2 as identified in Section XI.

Crack Parameters:

Wall thickness: 5.3750 File No.: HTCH-13Q-301 Revision: 0 Structural Integrity Associates, Inc. Page A2 of A19

Max. crack depth: 1.7369 Crack aspect ratio: 0.1000 Eccentricity ratio: 0.0809 Material yield strength: 43.9800 Co = Sigma(membrane) + Sigma(bending1 C1 = -2*Sigma(bending)/thickness

.................... Stress Intensity Factor--------------------

Crack Case Size Pm+Pb 0.0347 11.2398 0.0695 16.127 0.1042 20.035 0.1389 23.4618 0.1737 26.5972 0.2084 29.5368 0.2432 32 -3365 0.2779 35.019 0.3126 37.5813 0.3474 40.0759 0.3821 42.5163 0.4168 44.9493 0.4516 47.4081 0.4863 49.8445 0.5211 52.2636 0.5558 54.6691 0.5905 57.0644 0.6253 59.4522 0.6600 61.8349 0.6947 64.2631 0.7295 66.7181 0.7642 69.1766 0.7990 71.6397 0.8337 74.1747 0.8684 76.7368 0.9032 79.3096 0.9379 81.8935 0.9726 84.6138 1.0074 87.3613 1.0421 90.126 1.0769 92.908 1.1116 95.7075 1.1463 98.5247 1.1811 101.36 1.2158 104.27 1.2505 107.455 1.2853 110.666 1.3200 113.905 1.3548 117.219 1.3895 120.669 1.4242 124.149 1.4590 127.659 1.4937 131.297 1.5284 135.089 File No.: HTCH-13Q-301 Revision: 0 Structural Integrity Associafes, Inc. Page A3 of A 19

End of pc-CRACK O u t p u t File No.: HTCH-13Q-301 Revision: 0 Structural Integrity Associates, / n ~ . Page ~4 of ~ 1 9

pc-CRACK Output File for Weld N3A(N-SH) Indication 001, Emergency Condition trn pc-CRACK for Windows Version 3.1-98348 (C) Copyright '84 - '98 Structural Integrity Associates, Inc.

3315 Almaden Expressway, Suite 24 San Jose, CA 95118-1557 Voice: 408-978-8200 Fax: 408-978-8964 E-mail: pccrack0structint.com Linear Elastic Fracture Mechanics Date: Fri Feb 24 19:23:27 2006 Input Data and Results File: IND001C.LFM

Title:

HTCH-13Q, Weld N3A(N-SH), Indication #001, Emerg Condition Load Cases:

Stress Coefficients Case ID CO C1 C2 C3 Type Pmt Pb 73.97 -11.16 0 0 Coeff

Through Wall Stresses for Load Cases With Stress Coeff-------

Wall Case Depth J?m+ ~b 0.0000 73.97 0.1737 72.0316 0.3474 70.0933 0.5211 68.1549 0.6947 66.2166 0.8684 64.2782 1.0421 62.3399 1.2158 60.4015 1.3895 58.4632 1.5632 56.5248 1.7369 54.5865 Crack Model: Elliptical Subsurface Cracked Plate Under Membrane & Bending Stresses

Reference:

ASME Boiler and Pressure Vessel Code,Section XI, '86 Ed.

WARNING: The stress intensity factor (K) is the maximum of K at point 1 and K at point 2 as identified in Section XI.

Crack Parameters:

Wall thickness: 5.3750 Max. crack depth: 1.7369 Crack aspect ratio: 0.1000 Structural Integrity - File No.: HTCH-13Q-301 Revision: 0 Associates, lnc, Page AS of ~ 1 9

Eccentricity ratio: 0.0809 Material yield strength: 43.9800 Co = Sigma(membrane) + Sigma(bending)

C1 = -2*Sigma(bending)/thickness

.................... Stress Intensity Factor--------------------

Crack Case Size Pm+Pb 0.0347 16.275 0.0695 23.1449 0.1042 28.5041 0.1389 33.0955 0.1737 37.2053 0.2084 40.979 0.2432 44.503 0.2779 47.8264 0.3126 50.9744 0.3474 53.9919 0.3821 56.9001 0.4168 59.7758 0.4516 62.6729 0.4863 65.5122 0.5211 68.3016 0.5558 71.0478 0.5905 73.7561 0.6253 76.4313 0.6600 79.0773 0.6947 81.7777 0.7295 84.502 0.7642 87.2119 0.7990 89.9095 0.8337 92.629 0.8684 95.3498 0.9032 98.0649 0.9379 100.775 0.9726 103.688 1.0074 106.624 1.0421 109.565 1.0769 112.514 1.1116 115.469 1.1463 118.433 1.1811 121.405 1.2158 124.481 1.2505 127.988 1.2853 131.52 1.3200 135.075 1.3548 138.678 1.3895 142.358 1.4242 146.064 1.4590 149.795 1.4937 153.714 1.5284 157.865 1.5632 162.049 1.5979 166.266 File No.: HTCH-13Q-301 Revision: 0 Structural lntegrlty Associates, Inc. Page A6 of A19

1.6327 170.517 1.6674 174.8 1.7021 179.116 1.7369 183.465 End of pc-CRACK Output File No.: HTCH-13Q-301 Revision: 0 Structura/ lntegrlty Associates, Inc. Page A7 of A19

pc-CRACK Output File for Weld N3A(N-SH) Indication 001, Faulted Condition tm pc -CRACK for Windows Version 3.1-98348 (C) Copyright '84 '98 -

Structural Integrity Associates, Inc.

3315 Almaden Expressway, Suite 24 San Jose, CA 95118-1557 Voice: 408-978-8200 Fax : 408-978-8964 E-mail: pccrack0structint.com I

Linear Elastic Fracture Mechanics I1 Date: Fri Feb 24 10:37:21 2006 Input Data and Results File: IND001D.LFM

Title:

HTCH-13Q. Weld N3A(N-SH) , Indication 11001. Faulted 11 Load Cases:

1 case ID Pm+Pb Stress Coefficients CO 92 C1

-13.4 C2 0

C3 0

Type Coeff

Through Wall Stresses for Load Cases With Stress Coeff-------

Wall Case Depth Pm+Pb 1 Crack Model: Elliptical Subsurface Cracked Plate Under Membrane & Bending Stresses

Reference:

ASME Boiler and Pressure Vessel Code,Section XI, '86 Ed.

WARNING: The stress intensity factor (K) is the maximum of K at point 1 and K at point 2 as identified in Section XI.

Crack Parameters:

Wall thickness: 5.3750 Max. crack depth: 1.7369 Crack aspect ratio: 0,1000 I I File No.: HTCH-13Q-301 Revision: 0 Structura/ Inte~rity Associates, Inc. Page A8 of A19

Eccentricity ratio: 0.0809 Material yield strength: 43.9800 Co = Sigma (membrane) + Sigma (bending)

C1 = - 2

  • S i m a (bending)/thickness

.................... Stress Intensity Factor--------------------

Crack Case Size m + ~ b File No.: HTCH-13Q-301 Revision: 0 Structural lntegrit~t ssociates, Inc. Page A9 of A19

1.6327 214.914 1.6674 220.301 1.7021 225.728 1.7369 231.196 End of pc-CRACK Output File No.: HTCH-13Q-301 Revision: 0 Structural Integrity Associates, Inc. Page AIO of ~ 1 9 b

pc-CRACK Output File for Weld N3A(N-SH) Indication 002, Normal and Upset Condition tm pc-CRACK for Windows Version 3.1-98348 (C) Copyright '84 - '98 Structural Integrity Associates, Inc.

3315 Almaden Expressway, Suite 24 San Jose, CA 95118-1557 Voice: 408-978-8200 Fax : 408-978-8964 E-mail: pccrackQstructint.com Linear Elastic Fracture Mechanics Date: Fri Feb 24 09:52:44 2006 Input Data and Results File: IND002.LFM

Title:

HTCH-13Q, Weld N3A(N-SH), Indication #002 Load Cases:

Stress Coefficients Case ID C0 C1 C2 C3 Type Pm+ Pb 88.1 -22.85 0 0 Coeff

Through Wall Stresses for Load Cases With Stress Coeff-------

Wall Case Depth Pm+Pb 0,0000 88.1 0.1737 84.1313 0.3474 80.1625 0.5211 76.1938 0.6947 72.225 0.8684 68.2563 1.0421 64.2875 1.2158 60.3188 1.3895 56.35 1.5632 52.3813 1.7369 48.4125 Crack Model: Elliptical Subsurface Cracked Plate Under Membrane & Bending Stresses

Reference:

ASME Boiler and Pressure Vessel Code,Section XI, '86 Ed.

WARNING: The stress intensity factor (K) is the maximum of K at point 1 and K at point 2 as identified in Section XI.

Crack Parameters:

Wall thickness: 5.3750 Max. crack depth: 1.7369 Crack aspect ratio: 0.1000 File No.: HTCH-13Q-301 Revision: 0 Structural lnte#rity Associates, Inc. Page A l l of A19

Eccentricity ratio: 0.3247 Material yield strength: 43.9800 Co = Sigma (membrane) + Sigma (bending)

C1 = -2*Sigma(bending)/thickness

.................... Stress Intensity Factor--------------------

Crack Case Size Pm+Pb 0.0347 16.5744 0.0695 23.6745 0.1042 29.2828 0.1389 34.1449 0.1737 38.5463 0.2084 42.6321 0.2432 46.4871 0.2779 50.16 0.3126 53.6748 0.3474 57.0759 0.3821 60.3836 0.4168 63.6648 0.4516 66.9664 0.4863 70.2228 0.5211 73.4415 0.5558 76.6288 0.5905 79.7899 0.6253 82.9291 0.6600 86.0502 0.6947 89.2597 0.7295 92.5172 0.7642 95.7723 0.7990 99.0269 0.8337 102.391 0.8684 105.791 0.9032 109.201 0.9379 112.62 0.9726 116.219 1.0074 119.85 1.0421 123.5 1.0769 127.168 1.1116 130.856 1.1463 134.564 1.1811 138.292 1.2158 142.116 1.2505 146.301 1.2853 150.519 1.3200 154.768 1.3548 159.148 1.3895 163.777 1.4242 168.445 1.4590 173.152 1.4937 178.388 1.5284 184.283 1.5632 190.282 1.5979 196.263 File No.: HTCH-13Q-301 Revision: 0 Structural lntegrly Associates, Inc. Page A12 of A19

1.6327 202.346 1.6674 208.491 1.7021 214.696 1.7369 220.961 End of pc-CRACK Output File No.: HTCH- 13Q-301 Revision: 0 Structural Integrity Associates, Inc. Page A13 of A19

pc-CRACK Output File for Weld N3A(N-SH) Indication 002, Emergency Condition tm pc-CRACK for Windows Version 3.1-98348 (C) Copyright '84 - '98 Structural Integrity Associates, Inc.

3315 Almaden Expressway, Suite 24 San Jose, CA 95118-1557 Voice: 408-978-8200 Fax : 408-978-8964 E-mail: pccrack@structint.com Linear Elastic Fracture Mechanics Date: Fri Feb 24 19:24:26 2006 Input Data and Results File: IND002C.LFM

Title:

HTCH-13Q, Weld N3A(N-SH), Indication #002, Ernerg Cond Load Cases:

Stress Coefficients Case ID CO C1 C2 C3 Type Pm+Pb 73.97 -11.16 0 0 Coeff

Through Wall Stresses for Load Cases With Stress Coeff-------

Wall Case Depth m+Pb 0.0000 73.97 0.1737 72.0317 0.3474 70.0933 0.5211 68.155 0.6947 66.2166 0.8684 64.2783 1.0421 62.3399 1.2158 60.4016 1.3895 58.4632 1.5632 56.5249 1.7369 54.5865 Crack Model: Elliptical Subsurface Cracked Plate Under Membrane & Bending Stresses

Reference:

ASME Boiler and Pressure Vessel Code,Section XI, '86 Ed.

WARNING: The stress intensity factor (K) is the maximum of K at point 1 and K at point 2 as identified in Section XI.

Crack Parameters:

Wall thickness: 5.3750 Max. crack depth: 1.7369 Crack aspect ratio: 0.1000 File No.: HTCH-13Q-301 Revision: 0 Stnrctura/ Integrity Associates, Inc. Page ~ 1 of4~ 1 9

Eccentricity ratio: 0.3247 Material yield strength: 43.9800 Co = Sigma(membrane) + Sigma (bending)

C1 = -2*Sigma(bending)/thickness

Stress Intensity Factor--------------------

Crack Case Size pm+ Pb 0.0347 18.8857 0.0695 26.846 0.1042 33.0481 0.1389 38.3553 0.1737 43.1001 0.2084 47 -4522 0.2432 51.5117 0.2779 55.3404 0.3126 58.9766 0.3474 62.4612 0.3821 65.8186 0.4168 69.1519 0.4516 72.533 0.4863 75.8494 0.5211 79 .I102 0.5558 82.323 0.5905 85.4939 0.6253 88.6283 0.6600 91.7307 0.6947 94.9755 0.7295 98.2946 0.7642 101.604 0.7990 104.907 0.8337 108.257 0.8684 111.62 0.9032 114.983 0.9379 118.348 0.9726 121.994 1.0074 125.677 1.0421 129.375 1.0769 133.089 1.1116 136.819 1.1463 140.566 1.1811 144.329 1.2158 148.236 1.2505 152.721 1.2853 157.244 1.3200 161.803 1.3548 166.447 1.3895 171.233 1.4242 176.059 1.4590 180.925 1.4937 186.637 1.5284 193.41 1.5632 200.264 1.5979 207.196 File No.: HTCH-13Q-301 Revision: 0 8 Structural lntegriiy Associates, Inc. Page A15 of A19

1.6327 214.207 1.6674 221.294 1.7021 228.459 1.7369 235.698 End of pc-CRACK Output File No.:HTCH-13Q-301 Revision: 0 Structural Inteflrity Associates, inc. Page A16 of A19

pc-CRACK Output File for Weld N3A(N-SH) Indication 002, Faulted Condition tm pc -CRACK for Windows Version 3.1-98348 (C) Copyright '84 - '98 Structural Integrity Associates, Inc.

3315 Almaden Expressway, Suite 24 San Jose, CA 95118-1557 Voice: 408-978-8200 Fax : 408-978-8964 E-mail: pccrack@structint.com Linear Elastic Fracture Mechanics Date: Fri Feb 24 10:36:04 2006 Input Data and Results File: IND002D.LFM

Title:

HTCH-13Q, Weld N3A(N-SH), Indication #002, Faulted Load Cases:

Stress Coefficients Case ID C0 C1 C2 C3 Type m+Pb 92 -13.4 0 0 Coeff

Through Wall Stresses for Load Cases With Stress Coeff-------

wall Case Depth Pm+Pb 0.0000 92 0.1737 89.6726 0.3474 87.3452 0.5211 85.0178 0.6947 82.6904 0.8684 80.363 1.0421 78.0356 1.2158 75.7082 1.3895 73.3808 1.5632 71.0533 1.7369 68.7259 Crack Model: Elliptical Subsurface Cracked Plate Under Membrane & Bending Stresses

Reference:

ASME Boiler and Pressure Vessel Code,Section XI, '86 Ed.

WARNING: The stress intensity factor (K) is the maximum of K at point 1 and K at point 2 as identified in Section XI.

Crack Parameters:

Wall thickness : 5.3750 Max. crack depth: 1.7369 Crack aspect ratio: 0.1000 File No.: HTCH-13Q-301 Revision: 0 Structural Integrity Associates, Inc. Page ~ 1 of7 ~ 1 9

Eccentricity ratio: 0.3247 Material yield strength: 43.9800 Co = Sigma (membrane) + Sigma (bending)

C1 = -2*Sigma(bending)/thickness

Stress Intensity Factor--------------------

Crack Case Size m+Pb File No.: WCH-13Q-301 Revision: 0 Structural Integrity Associates, Inc. Page A18 of A19

1.6327 269.071 1.6674 278.001 1.7021 287.029 1.7369 296.152 End of pc-CRACK O u t p u t Stfucfural Integrity -File No.: HTCH-13Q-301 Revision: 0 Associates, Inc. Page ~ 1 of9 ~ 1 9

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