ML20094H398

IGSCC Flaw Evaluations & Weld Overlay Activities During Ei Hatch Unit 1 Fall 1991 Outage

ML20094H398
Person / Time
Site:	Hatch
Issue date:	02/29/1992
From:	Giannuzzi A, Gustin H STRUCTURAL INTEGRITY ASSOCIATES, INC.
To:
Shared Package
ML20094H395	List: HL-2080, Forwards Rev 3 to Rept SIR-91-077, IGSCC Flaw Evaluations & Welds Overlay Activities During Ei Hatch Unit 1 Fall 1991 Outage, in Response to NRC 920212 Request ML20094H398
References
SIR-91-077, SIR-91-077-R03, SIR-91-77, SIR-91-77-R3, NUDOCS 9203100128
Download: ML20094H398 (85)

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I Report No.: SIR 91077 Revision No.: 3 Project No.: GPCO.200 2 February 1992 I

I IOSCC Flaw Evaluations and Weld Overlay Activities During the E.1. Hatch Unit 1 I Fall 1991 Outage I

I Prepared for:

Georgia Power Company l Prepared by:

Structural Integrity Associates, Inc.

San Jose, CA Prepared by: < Date:

b

11. L Gustin Reviewed and //

Approved by: /) '

w-4mI7Pf . Date: 2!/I!'lL.-

~ p/rGiannuzzi //

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Table of Contents Section l' age 1.0 I NTR O D U Crl O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.0 INSPECTION RESULTS DURING 1991 ........................... 3 3.0 WELD OVERLAY DESIGNS AND RECONCILIATION WITil AS. BUILT I W E LD O VE R LA YS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.1 3.2 D e s ig n B a s i s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

We ld Ove rlay Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 5

5 I 3.3 3.4 Ferrite / Carbon Level Considerations . . . . . . . . . . . . . . . . . . . . . . . . . .

Comparison of Design and As. Built Weld Overlays . . . . . . . . . . . . . . .

6 9

3.5 Conclusions Regarding As. Built Overlays . . . . . . . . . . . . . . . . . . . . . . . 9 4.0 WELD OVERLAY SilRINKAGE EVALUATION . . . . . . . . . . . . . . . . . . . 14 4.1 Effects of Shrinkage on Piping Supports and Pipe Whip Restraints . . . 14 l 4.2 Effect of increase in Deadweight and Stiffness Resulting frorn Weld Overlays in the Piping Syste ms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 l 5.0 EVALUATION OF EMBEDDED INDICATIONS IN WELD O VE R LA YS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.1 Disposition of INF 191 H1015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.2 Disposition of INFs 191H1020,191H1021 and 191111024 . . . . . . . . . . . 27 6.0 EFFECrlVENESS OF IHSI AT HATCH UNIT 1. . . . . . . . . . . . . . . . . . . . 29 7.0 EFFECrlVENESS OF HYDROGEN WATER CHEMISTRY AT liATCH UNIT 1...........................................,........ 34 i 8.0 EVALUATION OF OBSERVED CRACK GROWTH IN FLAWED WELDS................................................... 36 9.0 CO N C LU S I O N S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.0 R E F E R E N CES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 APPENDIX A Weld Overlay Design Drawings APPENDIX B General Electric Plant istch Unit Crack Arrest Verification (CAV) System SIR 91077, Rev. 3 i I -

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I List of Tables Tabic hge l 21 Results of Inspections: Fhw Characterizations . . . . . . . . . . . . . . . . . . . . . . . . 4 31 Comparison of Design and As Built Weld Overlay Dimensions . . . . . . . . . . . 10 1 32 Measured Delta Fe rrite in First 1;iyers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 33 Calculated Carbon Content in Diluted Wdd Layers . . . . . . . . . . . . . . . . . . . 12 41 Measured Shrinkage Values 1991 Weld Overlays . . . . . . . . . . . . . . . . . . . . . 17 42 Shrinkage Stresses at Unrepaired Welds in llatch Unit 1 Recirculation System Following 1991 Overlays . . . . . . . . . . . . . . . . . . . . . . . 18 l 4-3 Piping System Unit Weights Used in Dynamic Analysis . . . . . . . . . . . . . . . . . 21 44 Results of Dynamic Analysis Comparison of Natural Frequencies for I First Twenty Modes With and Without Overlays . . . . . . . . . . . . . . . . . . . . . 22 51 Ide ntifie d Embe dde d Flaws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 6-1 Sustained Stresses in Unrepaired 12 inch Locations . . . . . . . . . . . . . . . . . . . 31 62 Sushined Stresses in Unrepaired Locations in Large (> 12 inch) Pipe . . . . . . 33 81 Comparison of Flaw Characte.izations with P.evious inspection Results . . . . 38 82 Weld Overlays: Design Thickness and Remaining Ligament . . . . . . . . . . . . . 39 I .

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I SIR-91-077, Rev. 3 l ii STRUCTURAL INTEGRITY

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I List of Figures I

Einitt Ease l 3-1 IGSCC Resistance Figure from Reference 6, with Worst Case 1991 llatch Data Points Added . . . ....................................... 13 41 Finite Element Models: Loo p s A a n d 11 . . . . . . . . . . . . . . . . . . . . . . .... 23 42 Hatch Seismic Response Spectra: Elev.146 ft. ....................... 24 43 Hatch Seismic Response Spectra: Elev.172 ft. ....................... 25 I

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1 SIR 91077, Rev. 3 iii 1

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I 1.0 INTRODUCrlON As part of the pre outage planning process r.t E.1. llatch Unit 1, Structural Integrity I Associates (SI) prepared weld overlay der.igns meeting the requirements of the NUREG-3313 Revision 2 [1] " Standard Weld Oserlay Design" for all unrepaired locations (2) prior to the Fall,1991 outage.

I During the Fall,1991 refueling and maintenance outage at the E.1. llatch Unit 1 Nuclear Power Station, Georgia Power (GPC) applied weld overlays to six locations in the recirculation and residual heat removal systems. The weld overlay designs were based upon g the previously developed designs. Five of these weld overlays were applied in response to observed indications representative ofIGSCC. The sixth overlay was applied to enhance the l inspectability of the underlying weld, although no llaw was observed in this location.

When overlays were completed, Si performed analyses of the weld overlay shrinkage induced stresses with the as applied weld overlays. Previous bounding analyses [3] had shown that l application of any combination of these overlays would not result in unacceptable shrinkage stress effects in the system.

I Section 2 of this report summarizes the GPC inspection pia.s initial scope and scope expansion, and the results of these inspections. Section 3 discussei the design basis weld overlays, and provides reconciliation of the design and as built dimet sions for all repairs.

Section 3 also discusses the observations made regarding 6 ferrite content in each weld overlays, and the Si conclusions regarding these observations. Section 4 d.scusses the effects of weld overlay shrinkage on the recirculation system. Section 5 summarizes the evaluation of observed embedded flaws in weld overlays including the criteria of ASME Section XI [7).

'I Section 6 evaluates the effectiveness of Induction licating Stress Improvement (111S1) applied previously to welds in the recirculation system, considering the cumulative effects of the weld overlays applied to the system. Section 7 discusses the effectiveness ofliydrogen l

! SIR 91077, Rev. 3 1 1

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Water Chemistry (HWC) at llatch. Section 8 addresses the observed changes in flaw I character under pre existing weld oserlays. Section 9 provides a summary of the report and the conclusions drawn from the previous sections.

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I 2.0 INSPECTION RESULTS DURING 1991 During the Fall,1991 outage at Plant Hatch Unit 1, GPC inspected intergranular stress I corrosion cracking susceptible welds in accordance with the requirements of Generic Letter 1

i SS 01 and NUREG 0313, Revision 2. The initial inspection plan included examination of 14 Category C welds,25 Category E welds, and all 4 remaining Category F welds. As a l

result of the inspection results during the initial scope, the inspection scope was expanded as required by the Generic Letter. Fourteen additional Category C welds were examined, as were all 21 remaining Category E welds. The combined inspection scope therefore included 28 of 73 Category C welds,46 of 46 Category E welds, and 4 of 4 Category F g welds.

l The inspection identified flaw indications in one Category C weld (28B 2) and confirmed or showed minor changes in four Category F welds. These inspection results are shown in l Table 21.

l Weld overlays meeting the design requirements of the NUREG-0313 " Standard Weld Overlay" were applied to the Category C weld (IB311RC-2SB 2) and all four Category F welds (1831-1RC 12BR-A4,1B31 1RC-12BR E4,1B31-1RC-12AR G4, and 1E11 1RHR-20B D 4). In addition, a standard weld overlay was applied to an additional Category C weld (1E11 1RHR 20B D-5) to improve inspectability of this weld, although no flaws were observed in this weld.

As a result of the weld overlay actaities, the overlaid welds are now reclassified as Category E welds for the purposes of future inspection. The Hatch recirculation system with related piping in the RHR system now .ludes 71 Category C welds,52 Category E welds, and no Category F welds.

I I SIR 91-077, Rev. 3 3 I srauctuam.

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1 Table 21 l Results of Inspections: Flaw Characterizations I

l Weld Category Before 1991 Flaw Characterization l 28B 2 C

1. Orientat' ion Circ Length 2.2" Depth 1 32 %

2 Cire 4.0 " 32rc 3 Circ 0.35" 1990 12BR A-4 F 1 Cite 4.0" 26fo 12BR.E 4 F 1 l Cire 4.4 " 329c 12AR.G 4 F ---- - Unable to Size -------- --

I 20B D-4 F 1 Axial -

10 15 %

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3.0 WELD OVERLAY DESIGNS AND RECONCILI ATION WITil AS DUILT WELD I OVERLAYS I 3.1 Design Basis I Piping load data for each weld location was taken from the General Electric (GE) stress report for the recirculation and RHR systems (4). Stresses were calculated from the load g

data based upon conservative values of wall thickness for each location. The weld overlay g designs are summarized in Table 31, and the design sketches are included in Appendix A.

l All weld overlay designs were prepared assuming a bounding 360' circumferentially oriented through wall flaw, in accordance with the requirements of the NUREG.0313, Revision 2

" Standard Weld Overlay" design. Design thicknesses were determined using the Si computer program pe CRACK [5).

I The overlay lengths shown are minimums required for effective reinforcement. Greater l lengths are acceptable, and may be required to allow for adequate inspection or for other reasons.

3.2 Weld Overlay Designs Weld overlays were applied to six locations during the Hatch Unit 11991 outage. Three of these weld overlays were applied to 12 inch pipe to safe end joints. Two were applied to 20 inch RHR suction welds, and one was applied to a 28 inch safe end to pipe weld. The I 2S inch location contained a newly identified flaw indication in a region where geometry indications had previously been observed. One of the 20 inch locations (weld 208 D 5) did not contain any identified Daws, but a weld overlay was applied using inconel 82 weld metal to improve inspectability of the location. The remaining four locations were previously classified as Category F, and contained previously identified flaw indications. Following the I SIR.91077, Rev. 3 5 I N STRUCTURAL INTEGRITY ASSCX;lATESINC

I weld overlay of these latter four welds, there are no remaining Category F welds in the flatch recirculation system.

I 3.3 Ferrite / Carbon Level Considerations I Two welds in large diameter piping (>12 inch) in the llatch I recirculation and RilR g systems contain flaw indications which were repaired by the weld overlay technique using Type 308Lstainless steel weld metal. The weld overlay locations are welds 1B31 1RC 28B 2 l and 1E111RilR 20B D 4. In addition, three welds in the 12 inch recirculation discharge piping were repaired by weld overlay using Type 308L stainless steel weld metal. These l welds are 1B31 1RC 12BR-A4,1831 1RC-12BR E4,and 1B31 1RC 12AR G4. Delta ferrite measurements were made following the completion of the first layer of each of these weld overlays, and in one case following the second and third layers, and the results are summarized in Table 3 2.

I Austenitic stain! css steel materials with delta ferrite content equal to or greater than 7.5 FN and with carbon content of 0.035 wtG max have been shown to be resistant to IOSCC.

Also, where carbon content is less than or equal to 0.035 wt%, wrought austenitic stainless steels like Types 304L and 316L have been shown to be IGSCC resistant even with no delta ferrite present. If ferrite content is less than 7.5 FN but greater than 5.0 FN,it is possible to justify the IGSCC resistance of the resulting weld metal on a case by case basis, by considering a trade off between delta ferrite content and carbon content,if the carbon level Ie is less than 0.035 wt%. Note that the 6 ferrite issue does not apply to weld 20B D 5.

1 This approach is allowed by NUREG 0313, Revision 2, and has been successfully used previously at Hatch and other plants. The purpose of such an evaluation for llatch is to demonstrate the IGSCC resistance of the first weld layers of the weld overlays above, in g order to justify including these layers in the design thickness of the overlays, when the ferrite level is above 5 FN and below 7.5 FN.

I SIR 91077, Rev. 3 6 2 muerum INTEGRITY I ASSCCIATESitC

I The carbon content in the underlying base incial at each of these fhe weld overlay locations is reported in Table 3 2, based upon data from the component CMTRs. Two heats of weld metal were available for use in these overlays. Ileat # PB940, which was used for the first

!ayers of all of the locations except the G4 weld, has a reported carbon content of 0.008 7c.

Heat # S57735, which was used for the G4 weld, has a carbon content of 0.014?c reported I in the CMTR.

I For both of the above weld rnetal heats, the carbon content is sufficiently low that the as.

deposited carbon content of the first welded layer qualifies as !GSCC resistant (< 0.035 wt Fo), even considering dilution of the first layer weld metal by the higher carbon base metal during the welding process. Consequently, there is significant benefit to be derived from a case by case evaluation of the ferrite carbon trade off at these two locations.

In order to characterize the first welded layer carbon content for these weld overlays, a g dilution rate for the dilution of the first welded layer by the base metal was determined, based upon physical examination and chemical analysis of the diluted first layer of welded l coupons made using the same welding procedures as were used in weld overlay application.

This led to a predicted dilution rate of 32.5 fc. Using this dilution rate, the first layer of l each of the applied weld overlays was calculated to have carbon content as shown in Table 3 3. In all cases, the diluted carbon level in the first layer is less than 0.035 wtro. These l carbon contents meet the NUREG 0313 criterion for conforming IGSCC-resistant austenitic stainless steel base metal, even if no ferrite is present. The first layer weld materialis also predicted to be IGSCC resistant by the results illustrated in Figure 31 from Reference 6 even with 5 FN delta ferrite, which is the lowest delta ferrite allowed by NUREG 0313, Revision 2 for conforming austenitic stainless steel weld metal.

I Figure 31 includes data points representative of each of the five stainless steel weld overlay locations. These data have been superimposed on the Reference 6 curve and data. These s weld overlay data points reflect the as diluted first layer carbon content, and t!.e lowest I SIR 91077, Rev. 3 7 I m sraucrunn INTEGRITY

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I measured delta ferrite point reported for each weld. This illustrates that the lowest l measured delta ferrite which could be justified for acceptance of the first welded layer (S FN), is limited by the NUREG criteria (discussed below) rather than by the data in Figure I 3 1.

j I Although the above results support the position that the first layers of all five welds are sufficiently IGSCC resistant by the critelia of Figure 31, NUREG 0313, Revision 2 contains a cut off rninimum level of 5 FN which is defined to be IOSCC resistant. Based upon this requirement together with the above considerations, the first layers of the weld overlays on g

weld 28B 2 and 20B D 4 are considered as IGSCC resistant and therefore could have been g included as a part of the structural reinforcement weld material used in meeting the design thickness. The first layer of the overlay on 28B 2 was conservatively not considered as part l of the design thickness however. The first layer of the overlay on weld G4 is acceptable since all measured delta ferrite data are greater than 5 FN. The first layer of the overlay l on weld E4 is not acceptable by the 5 FN minimum criterion, nor are the first two layers of the overlay on weld A4. The third layer of the overlay on weld A4 meets this criterion.

Additional weld layers were added to the E4 and G4 welds to achieve a weld layer meeting the NUREG criterion. The weld metal considered in ineeting the design thickness was only l that including and outboard of the conforming layer.

The weld overlay design drawings for these five overlays all contain a note stating that the first layer of the overlay must have delta ferrite greater than 7.5 FN. The intent of this note is that a first welded layer with measured delta ferrite equal to or greater than 7.5 FN is acceptable for inclusion in the design thickness without fur.Lber evaluation (in accordance with NUREG 0313). As discussed above, lower levels are acceptable following case by case evaluation.-

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I 3.4 Comparison of Design and As 13uilt Weld Overlays I

Contingency weld overlay designs for the six overlaid locations were originally presented in

[2). The design for weld 2813 2 was revised to account for the as measured component wall thickness on the safe-end side of the weld. The as rneasured thickness data for the other weld overlays applied during this outage (welds 12 AR 04,12 BR A4,1213R E4,20ll D 4 and 20 B D 5) were re iewed and found to have no impact on the designs previously issued in [2]. The designs for the three 12 inch welds and weld 20B D 5 were modified subsequent to [2] only to illustrate the detail of blending the overlay into the adjacent component transitions. The design thicknesses of these overlays remain the same as in the previously g issued revision [2].

l 3.5 Conclusions Regarding As Built Overlays l Table 31 presents the design and as built dimensions for the weld overlays applied during the 1991 outage. Thickness measurements (t) only represent layers which met l d ferrite / carbon criteria as presented in Section 3 3 for stainless steel overlays. These layers were included in meeting the design thickness. Additionallayers inboard o'inese layers may l not have met 6 ferrite requirements and were not included in the design thickness. As may be seen from this table, the dimensions of the as built overlays meet or exceed the design dimensions in nll cases. All of these six weld overlays therefore may be considered to meet the requirements of the NUREG 0313, Revision 2 " Standard Weld Overlay" category.

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" Table 31 Comparison of Design and As Built Weld Overlay Dimensions I . _

Average Average l 'fld e Design t (in)

Design L (in)

As Built t (in)l 2 As Built L (in) l 12BR A 4 12BR E.4 0.27 0.27 2.0" 2.0" 0.44/0.43 0.4/0.37 2.1 2.1 12AR G 4 0.26 2.0" 0.31/* 2.2  !

288 2 0.52 8.0 0.57/0.69 8.4 20B D 4 0.36 6.0 0.44/0.44 6. 2 " "

208 D 5 0.33 0.5/0.39 Measurement not meaningful due to transition angle.

Length on pipe side only; on component side (safe end, vahe). b!:.A into component transition.

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Upstream, blend into adjacent overlay, downstream, blend into transition.

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Downstream, blend into adjacent overlay.

Note: 1. All thicknesses are shown on upstream and downstream sides of girth l weld centerline.

2. Reported thicknesses are only for layers which met the 6 ferrite / carbon l levels of Section 3.3 for stainless steel overlays.

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M M M M W W W M M M M M m M M M M M M Tabic 3-2 Measured Delta Fenite in First Layes 4

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1st 1sver l

W 270 0 W ISO 270 0 W Im 770 Weki N-uter locatem 0 Ife 1 B11-1 RC-251L2, N!R 6 63 73 8 75 8 75 KR AR KR Safe-Isof 73 6 53 63 3 73 73 8 KR NR NR N.R hpe 6 rrraso Weld were IIT* TB940 PTN4n 0 (EIR 0MW W.M. *rrC 0 On8 B M. %C = 0 055 1E11-1RIIR-20fLIL4, 73 73 7 7 85

• 85 9 Ik=twneam 65 6 53 6 6 6 63 6 5 5 65 6 65 6 U; wemm 6 6 ftM40 PfMa Weid We*e Itis FB940 e tvg 0 fun W M. %C 0 trm B M. %C = 0 0%

1H31-1RC-! DR-A 4, 7 4 73 15 6 6 6 7 63 Safe I rx! 4 33 5 7 75 53 6 5 65 55 6 6 73 6 73 Pere Pfraso WelJ Wwe 1il a rB940 FIM*3 OME O few WM.TC O fm H M. %C = C 075 IH31-IRC-12BRT 4, NR 53 1n5 93 9. 4 10 K13 RR KR safefnd 5 5.5 43 KR 83 85 8.5 83 MR MR NS -

hpe 53 6.5 65 53 I Weld Wwe IITs TH940 557735 W M. %C 0(ns 0.014 j

D M. *5C = 0 Os7 1 Bil-I R C-12. ARC, 4, N3 93 83 85 KR KR N!R Safe 4ruf 73 8 8 65 10 %

83 93 KT, N.R N.R NA Prpe 8 9 8 73 95 to j

Wekt Wee IITs 557735 5577M 0 014 0 014 W M. %C

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fBM.4C=0075 ,

Weld Were ERy*I, lit # Ffi9so,ofwE*=C,122FN (Megna Gage) per CMTR ,

l Weld Wre ER30RI.,:ITd 557735.0014SC. IIFN (Fig. Nit-24RI-I} Fr CMTR l

N SIR-91-077 Rev. 3 11 / /GOCIATCSIIC

I Table 3 3 Calculated Carbon Content in Diluied Weld Layers I

Weld # Ilase Carbon Fo Weld Cbhon Fo Diluted Carbon rc _

28112 0.055 0.008 0.0233 I 20B D.4 0.056 0.008 0.0236 l 12BR A 4 0.075 0.008 0.0298 1213R E.4 0.047 0.008 0.0207 12AR G 4 0.075 0.014 0.0338 I >

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I 4.0 WELD OVERLAY SilRINKAGE EVALUATION When weld overlays were completed, measurements of axial shrinkage due to the weld overlay application were made as presented in Table 41. Si performed analysis of the weld g overlay shrinkage induced stresses at alllocations on the affected piping, considering all weld overlays (1991 and presious). Previous bounding analyses (3) had shown that application of l any combination of these overlays would not result in unacceptable shrinkage stress effects la the system, t\ finite element model of each loop of the Hatch I recirculation system was developed.

l The as mea;ured shrinkage resulting from the application of all overlays on the loops, including the overlays applied during the 1991 outage, were imposed on the models. The stresses due to the aggregate shrinkage on each loop were calculated at each unrepaired location.

I The shrinkage stress results at each unrepaired location are presented in Table 4 2. These stresses are judged to be generally insignificant with regard to integrity of the piping system, but should be considered in any future flaw evaluations or crack growth calculations on these systems.

I 4.1 Effects of Shrinkage on Piping Supports and Pipe Whip Restraints I Subsequent to the application of weld overlays, visual inspections of piping supports and whip restraints were perfortned by GPC. These inspections included verification of spring .

hanger lcad settings, snubber pin to pin and stroke dimensions, and pipe whip restraint g clearances for all piping supports in the recirculation loops. As-built dimensions were documented by 151 personnel, and were evaluated against design regt'irements. The results of these inspections showed that the as built condition of piping supports is acceptable, with SIR 91077, Rev. 3 14 sraucwan INTEGRITY I / ASSOClKI'E3ING

i no impact on plant operation. No adjustments to piping support settings or whip restraint clearances were required.

I 4.2 Effect of Increase in Deadweight and Stiffness Resulting from Weld Overlays in the Piping Systems When the mass of the piping system increases due to the number of weld overlays, the dynamic characteristics of the system also change. These changes may have an effect on the g seismic stress due to varying the modal response of the system. Therefore, a second analysis was performed to examine the effect of additional weld overlays on the modal frequencies of the recirculation piping system.

The model used for the modal analysis is based en the weld shrinkage finite element model with some modifications to permit it to be used for a dynamic analysis. These modifications l include adding the weight of the piping, valves, pump, motor, and weld overlays and the snubber stiffnesses.

I Table 4 3 presents the unit weights of the recirculation system using nominal pipe sizes. The unit weights include the pipe, water and insulation. The weight of the pump is 67100 lbs.

and the weight of the valves are 10188 lbs. cach. The weight of the overlays were calculated assuming the overlay thickness is 0.5 inch and the overlay length is 6 inches. These are l

nominal overlay sizes, however the analysis results will not be significantly affected due to as built variations in these values. The resulting overlay weights are 76.16 lbs. for a 28 inch l pipe,60.13 lbs. for a 22 inch pipe and 35.41 lbs, for a 12 inch pipe.

A total of 11 snubbers was included in the recirculation system dynamic model. Two were placed on the suction side (SB7 & SBS). Three were placed on the discharge size _(SB12, SB13 and SB14). The rest of the snubbers were used to restrain the pump and motor.

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For the SB14 snubber, the stiffness was estimated from load and displacement results of the piping seismic analyses performed by GE. The stiffness was estirnated to be about 1.4 x 10' lb/in. The stiffness of the remaining snubbers (SB7, SBS, SB12 & SB13) were estimated from other recirculation piping dynamic analysis. These were estimated to be about 0.5 x g 10'lb/in and were used at the pump location in the piping model to simulate all the snubbers connected to the pump and the motor. All other hangers in the recirculation piping were neglected because of low stiffness. All noz:les in the recirculation piping system were assumed to be fixed. Also, all welds in the recirculation system were assumed to be overlaid.

l This assumption is consistent with the most added mass to the piping system, and therefore, the most potentialimpact on the piping system dynamic analysis.

I Table 4 4 presents the modal response analysis results. The first mode was found to be

, l about 5.52 bz. for the recirculation system without any overlays. With the overlays, the first mode frequency decreases to about 5.49 bz. for a difference of 0.68%. The biggest difference is about 2.1% for mode 20.

Figures 4-2 and 4 3 present the Hatch Unit I response spectra at reactor vessel elevations 146 ft. and 172 ft. They both show a peak response at a frequency range of about 3.5 hz.

to 5 hz. With the first mode of 5.52 hz. when there are no everlays, the response is very close to the peak of the spectrum. Even though a decrease in the mode frequency would I correspond to an increased response for the given spectrum, the magnitude of the decrease in the first mode frequency is so small that it would not cause a significant change in the response. With only about 50% of the welds overlaid, the change in the first mode frequency would be even smaller. Therefore, it is concluded that the overlays, either in the current or any imagined future configuration, would have a negligible effect on the dynamic analysis of the system.

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1 Table 41 g

Measured Shrinkage Values 1991 Weld Overlays Weld Shrinkage (avg)

I (in)

(Max) 12BR A-4 0.10 0.14 I 12BR E 4 0.20 0.25 12AR G 4 0.32 0.37 g

28B 2 0.05 0.1 l 20B D 4 20B D 5 0.00 0.01 0.00 0.06 I

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Table 12 Shrinkage Stresses at Unrepaired Welds in Hatch Unit 1 Recirculat:3n System Following 1991 Overlays Weld Shrinkage Stress l (ksi) 28A-1 0.15 2RA 3 0.12 20 A 5 0.12 I 28A 5A 0.25 28A 9 0.25 28A.11 0.11 28A-13 0.19 28A-15 0,42 28A-16 0.46 28A-17 1.35 12AR F-1 6.77 12AR-F 5 2.89 12AR-G-1 3.09 12AR G-2 2.26 12AR-G 5 7.32 12AR-H-1 10.43 12AR-H 5 6.83 12AR.J-1 4.66 12AR-J-2 4.31 12AR-J-4 7.20 12AR-J-5 8.58 SIR-91-077, Rev. 3 18

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E Table 4-2 (continued)

Shrinkage Stresses at Unrepaired Welds in Hatch Unit 1 Recirculation System Following 1991 Overlays

I.

E Weld Shrinkage Stress (ksi) l 12AR K 1 12AR K-4 5.3' 2.8i' I

12AR K 5 3.65 28B 1 0.32 28B 5 0.80 28B-6 0.93 28B 7 0.41 i

288 12 0.38 28B-17 0.55 l 28B-18 22AM-2 1.59 1.94 22AM-3 1.41 22BM 2 1.52 22BM-3 0.89 20B D-1 0.31 I 20B-D-2 0.11 12BR A 1 5.92 i 12BR A-2 1.37 l

12BR-A-3 0.18 12BR-A-5 2.17

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12BR-B-1 5.68 l

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I Table 4 2 (concluded)

Shrinkage Stresses at Untepaired Welds in Hatch Unit 1 Recirculation System Following 1991 Overlays Weld Shrinkage Stress (ksi) l 12AR K-1 12AR K-4 19 1.59 12AR K 5 1.57 28B-1 12.93 28B-5 6.02 28B-6 5.51 28B 7 6.33 I -

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I Table 4-3 I Piping System Unit Weights Used in Dynamic Analysis I Unit Weight (lb/ft)

I Item Pipe Water Insidation Total (Ib/in) 28" Pipe Suction 330 208 38 48.00 28" Pipe Disch. 389 208 38 52.92 12" Pipe 91 42 20 12.75 22" Pipe 242 127 31 33.33 I

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Table 4-4 Results of Dynamic Analysis Comparison of Natural Frequencies for First Twenty Modes . With and Without Overlays I

I w/o overlays Recirculation Loop w/ w/o w/

overlays overlays overlays Mode (hz) (hr) Diff(%) period (sec) 1 5.5245 5.4867 -0.68% 0.181010 0.182260 2 6.9959 6.9255 -1.01 % 0.142940 0.144390 3 7.6848 7.6461 -0.50% 0.130130 0.130790 4 9.6416 9.6114 -0.31 % 0.103720 0.104040 5 10.4640 10.3410 -1.18% 0.095567 0.096702 6 12.5700 12.5350 -0.28% 0.079554 0.079777 7 14.4610 14.3010 -1.11 % 0.069149 0.069924 8 15.0970 15.0110 -0.57% 0.066237 0.066619 9 16.8210 16.7190 -0.61 % 0.059450 0.059811 10 18.1080 17.9230 .1.02% 0.055224 0.055796 11 18.2680 18.0110 -1.41 % 0.054740 0.055521 12 19.2290 19.1100 -0.62% 0.052005 0.052327 13 20.6930 20.3850 -1.49% 0.048324 0.049056 14 22.7780 22.4370 -1.50% 0.043901 0.044569 15 26.7640 26.6590 -0.39% 0,037364 0.037511 16 29.3070 29.1600 -0.50% 0.034122 0.034294 17 34.6740 34.4310 -0.70% 0.028840 0.029044 18 36.5010 35.9100 -1.62% 0.027396 0.027847 38.2240 -1.90% 0.026162 0.026669 I 19 20 39.7990 37.4960 38.9620 -2.10% 0.025126 0.025666 I

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I Figure 4-1. Finite Element Models: Loops A and B SIR 91-077, Rev. 3 23 gygggggjggt g INTEGRITY )

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23M 082 gn, ue, $ 0 NU31.IAR ENEROY IU5tNE55 CFERATIONS GENERALOstictnic m tv. 2 I

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, ,, ,,,, m mim m m .essroou.." o l Figure 4-3. Hatch Seismic Response Spectra: Elev.172 ft.

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5.0 EVALUATION OF EMBEDDED INDICATIONS IN WELD OVERLAYS During the irspection of previously applied weld overlays at Hatch Unit 1, sub wrface flaws I that are characteristic in most cases of lack of fusion were identified in several locations.

These locations and ikws are summarized in Table 51. These indications were documented in Georgia Power Company INFs 191H1015,1020,1021, and 1024.

I 5.1 Disposition of INF 191H1015 I This INF documents the flaws observed in the weld overlay on weld 28A-7. These flaws are g summarized in Table 51. Six of the seven obse'ved flaw indications were previously observed. In addition, a previously unobserved flaw indication (Indication #3) was observed.

l The new flaw indication (Indication #3) is acceptable without further action or repair. This conclusion is based upon the following considerations:

1. There is a remaining ligament of 0.64 inch outboard of the reported Indication

1. 3. The design overlay thickness for this repair location is 0.49 inches.

Therefore, the full design thickness of the overlay is outside of the Gaw indication, and the adequacy of the weld overlay is in no way affected by this flaw.

2. The indication is remote from other lack of fusion indications. The nearest of the other fabrication related defects appears to be Indication #1, which is located approximately 1 inch axially and 6 inches circumferentially from this I indication.

I 3. All other reported lack of fusion indications are located on the other side of the original girth weld.

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4. The reported location of the indication appears to be sufficiently far away from the underlying IGSCC flaw indication that there is little potential for connecting with the inside surface of the pipe. There is therefore no recognized mechanism for flaw growth.

I 5. This flaw indication and the other five indications can all be treated as unconnected to each other for the purpose of evaluation. Each of the reported indications is acceptable by the criteria of IWB-3500 of ASME Section XI [7).

l 5.2 Disposition of INFs 191H1020,191H1021 and 191H1024 The indications documented on INF 191H1020 (weld 2SB-15,11/1/91), and INF 191H1024 (weld 24B R-12,11/07/91) are summarized in Table 5-1. The indications reported in these l INFs are acceptable without further action or repair. This conclusion is based upon the following considerations:

1. There is a remaining ligament outboard _of the reported indication in excess of the weld overlay design thickness at each indication location. In other words, the full design thickness of the overlay is outside of the flaw indication depth in all cases, and therefore the adequacy of the weld overlay is in no way affected by these flaws.

2. Each of the reported indications is acceptable by the criteria of IWB-3500 of ASME Section XI, using Table IWB 3514-2 [7].

3. For these embedded flaws, there is no apparent mechanism for continued growth, since there is no detected connection with the inside surface of the pipe.

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I Table 5-1 loentified Embedded Flaws I

Weld Type of Flaws 28A 7 Lack of Fusion (6 Total) 28B-15 Lack of Fusion (1 Total)

-l 24B-R-12 Lack of Fusion (7 Total)

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I 6.0 EFFECflVENESS OF IHSI AT HATCH UNIT 1 I

NUREG-0313, Revision 2, Section 4.5 states in part that "Because the effectiveness of the SI [ stress improvement) treatment is also related to the applied stress on the weldment, l mitigation by SI is not recommended for weldments with senice stresses over 1.0 S,...", In practice, this limitation has been interpreted to mean that no credit may be taken for IHSI or other stress improvement methods at weld locations where the sustained stresses (pressure, deadweight, thermal expansion, and weld overlay induced shrinkage stresses) total more than 1.0 S,.

Tables 6-1 and 6-2 summarizes the sustained stresses at all locations in the Hatch recirculation system which have not received weld overlays. None of these 'ocations have identified unrepaired flaws. As can be seen from these tables, several locations in 12-inch pipe have combined sustained stresses greater than 1.0 S., while no locations in larger pipe I have sustained stresses greater than 1.0 S,. If future inspection results indicate that any of these highly stressed locations in 12 inch pipe have flaws requiring evaluation in accordance with the NUREG, the as welded residual stress distribution will be used in any crack growth calculations, rather than the more favorable post !HSI residual stress distribution. At other locations in the recirculation system, credit for IHSI may be taken consistent with the requirements in Section 4.5 of the NUREG.

As stated above, NUREG-0313 Revision 2 does not consider stress improvement treatments to be effective for weldments with senice stresses over 1.0 S., due to the concern that the stress improvement might be reduced by an overload or stress relaxation condition.

Laboratory data has illustrated that, for unflawed weldments, IHSI is an effective mitigation measure against IGSCC for loadings well above the engineering yield strength at temperature,i e.1.2 a, [8].

y When flaws exist in the structure, the mitigation measure may not be effective even at loads of S . The EPRI-GE Degraded Pipe Test Program [9] on four inch and twelve inch schedule 80 pipes obsened that: "The IHSI treatment of welded 1

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piping will proside crack arrest where IGSCC cracks are approximately 17Fc of wall thickness or less, prosided loading higher than the primary membrane stress (S.) is avoided....... At higher applied stresses, the compressive residual stress benefit afforded by the IHSI treatment is lost and crack growth occurs".

The flaws in the IGSCC Category F weldments were all sized at greater than 17Fo through wall and thus would have been expected to exhibit some growth. That is the principal reason that these welds have been subject to inspection during each refueling outage and g why Georgia Power Company decided to overlay repair all Category F welds.

The deepest IGSCC indication in weld 28-B2 was located in the same vicinity where root geometry had been called in the past. It is possible that the refined automated P. Scan and GE Smart 2000 detection capability used for inspection during this outage was able to resolve this indication as an IGSCC indication where previously, only a geometry call had l been made usine se manual inspection techniques. Discussion with the UT level 3 inspector reve_.ed that the capability of the new GE Smart 2000 automated UT system with l digital signal data storage produced a significantly increased capability to resolve indications following the inspection. The detailed flaw evaluation can be performed remotely thereby reducing human radiation exposure and allowing for a more precise examination of the component.

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Sustained Stresses in Unrepaired 12 Inch 1.ccations I

Weld Sustained Stress (ksi)3 l 12AR F 1 12AR-F-5 18.7 15.6 12AR-G 1 15.5 12AR G 2 9.9 12AR-G-5 15.9 12AR-H 1 27.6 12AR H-5 21.0 12AR.J-1 17.0 12AR-J 2 12.3 l 12AR-J 4 12AR-J-5 20.8 22.2 12AR.K-1 16.6 12AR-K-4 13.3 12AR K-5 14.1 12BR A-1 18.6 I 12BR-A-2 9.0 12BR-A 3 7.3 12BR-A 5 13.9 12BR-B-1 18.9 Note: 1. Sustained stresses include pressure, deadweight, thermal, and shrinkage stresses.

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Table 6-1 (continued)

Sustained Stresses in Unrepaired 12 Inch I.ocations I

h Weld Sustained Stress (ksi) l 12BR-B 2 12BR-B-4 10.3 12.3 12BR B-5 12.2 12BR-C-1 31.3 12BR-D-1 18.3 12BR D-4 16.6 I 12BR-D 5 17.4 12BR E-1 20.5 I

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Table 6-2 I Sustained Stresses in Unrepaired Locations in targe (>12 inch) Pipe I -

Weld Sustained Stress

_l (ksi)1 28A 1 6.7 28A 3 6.4 28A-5 6.3 28A 5A 6.4 28A 9 6.8 28B 1 7.5 l 28B-5 28B-6 7.4 7.8 l 28B-7 20B-D-1 7.1 9.9 20B D 2 8.1 28A-11 5.8 28A-13 5.8 28A-15 6.9 28A-16 6.8 288-12 5.9 g

28B-17 7.7 I Note: 1. Susta:ned stresses include pressure, deadweight, thermal, and shrinkage stresses.

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I 7.0 EFFECTIVENESS OF HYDROGEN WATER CHEMISTRY AT HATCH UNIT 1 g The hydrogen water chemistry mitigation . measure is an extremely effective IGSCC mitigation measure in sensitized austenitic stainless steels if the electrochemical potential l (ECP) of stainless steel in the BWR environment is reduced to a level below the protection potential of -230 mv SHE at the BWR operating temperature. It has been demonstrated l in laboratory programs that a factor of improvement of more than 10 can be expected in reduction in crack growth rates in the protective HWC environment. When combined with excellent water quality, this mitigation measure is extremely effective in reducing or eliminating IGSCC in the BWR emironment.

During the past few years, the hydrogen water chemistry system has been installed at Hatch and has operated during power operation. Prior to this operating cycle, cycle 13, the hydrogen system was unable to consistently reduce the electrochemical potential to below the protection potential for stainless steel. During the prior refueling outage, the condenser was changed from a copper based condenser to a titanium condenser in part to assist in I reducing the electrochemical potential to below the protection potential. During this operating cycle, the hydrogen injection system was consistently able to reduce the elec;rochemical potential to below the protection potential.

The water chemistry records at Hatch Unit I were reviewed to determine the water quality during operating cycle 13 as well as the effectiveness of the hydrogen injection system. The ECP was obtained in the crack arrest verification system (CAVS) autoclave. The CAVS g results revealed that the HWC system was on and produced full protection for approximately 41% of the time at power. During the remaining 59% of the time the system was either partially protective er not protective. The total time in which no protection was observed was approximately 479c of the time at temperature and pressure. No investigation was l performed to ascertain why the system was providing no protection during this period of time during the cycle. However, it is noteworthy that for approximately 4500 hours0.0521 days <br />1.25 hours <br />0.00744 weeks <br />0.00171 months <br /> during I SIR-91-077, Rev. 3 34 sraueru m INTEGRrfY I

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I this latest cycle, the HWC system was not providing effective protection to the recirculation I system piping. Clearly, that quantity of time is adequate for additional IGSCC or crevice corrosion to occur in the oxidizing BWR environment. This additional crack initiation or growth is consistent with that observed during the IGSCC inspections following cycle 13.

Additional detailed discussion of the operation of the HWC system during cycle 13 is presented in Appendix B to this report, prepared by the General Electric Company.

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I 8.0 EVALUATION OF OBSERVED CRACK GROWTH IN FLAWED WELDS g During the 1991 inspection, several locations yielded inspection results indicative of flaw growth. Inspections prior to 1991 were performed manually, while the 1991 inspections were g performed using automated P. Scan. The difference in inspection technique could be responsible in part for the recorded changes in indications. A comparison of prior and 1991

.l inspection results is presented in Table 8-1.

l Two of the four existing Category F welds had identified flaw characteristics slightly different from previous inspection results. Weld 12BR-A4 had observed flaw depth of 26% as compared to the previous result of 17-229. Weld 12BR E4 had observed flaw depth of 32%, as compared with the previous result of 21-25%. These differences are considered to be within the bounds of the accuracy of the inspection technique, and are not indicative of significant crack growth. Both of these locations, as well as the other two Category F welds (12AR-G4 and 20B-D-4), were repaired during the 1991 outage using weld overlay designs qualifying as NUREG-0313 " Standard Weld Overlay" repairs. These welds therefore are reclassified as Category E locations for future inspections.

I In addition to the above Category F welds, three locations with existing weld overlays had recorded inspection results which are indicative of flaw growth under the overlays. These three locations are welds 12-AR-H3, 12 AR-J3, and 24B-R-13. The new flaw characterizations for these locations show a maximum flaw depth within the outer 25% of the original base material. In no case was propagation into the weld overlay material

, observed. The reported remaining ligament outside of the crack depth for each of these three locations is summarized in Table 8 2.

I Flaw growth calculations for these flaws, to determine if such growth is in line with l predictions made in accordance with the methods of NUREG-0313 are not meaningfulin these cases, since the starting depth of the underlying flaws is not known.

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. - The weld overlays for these locations were applied in 1984. At that time, the reported flaw lengths on the two 32 inch weld locations (360' intermittent) were such that a repair was required regardless of flaw depth. It was determined that the weld overlay design would not

,I be affected by flaw depth, and so the decision was made to rninimize radiation exposure to the inspection personnel by not requiring detailed depth sizing. Consequently, an accurate starting depth for use in fla'v growth calculations is not available.

The flaw on weld 24B R-13 was reported in 1984 as axially oriented and 47% deep. The recent inspection report:d axial flaws with depths nearly through original pipe wall. This is not inconsistent with the fact that sizing of axial flaws was imprecise at best in 1984, and is still difficult today, especially through a weld overlay. The 1991 re},orted depth of the axial flaws in this weld may be indicative of either inspection variations or flaw growth, or l a combination of both. In any case, the observed flaws do not reduce design margins in the weld overlay.

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Comparison of Flaw Characterizations with Previous Inspection Results I WELD OVERLAY LOCATIONS: )

l 12AR H3:- OVERLAY 1984: 360 X 20-30%

1991: CIRC 3.8" X TO OVERLAY INTERFACE CIRC,1.3" X 0.06 BELOW OVERLAY 12AR J3: OVERLAY 1984: 360 X 20-30% <

1991: CIRC,1,3" X 0.12" BELOW OVERLAY g

l 24B R 13: OVERLAY 1984: AXIAL X 47%

1991: MULTIPLE AXIALS DEEPEST TO 0.4" OF OD I CATEGORY F:

I 12BR-A4: PREVIOUS: 17 22%, PRESENT: 26%

12BR-E4: PREVIOUS: 21-25%, PRESENT: 32%

12AR-G4: PREVIOUS: 13-19%, PRESENT: UNABLE TO SIZE DUE TO CONFIGURATION 20B D-4: PREVIOUS: 16% AXIAL, PRESENT: 10-15% AXIAL I

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Table 8 2 Weld Overlays: Design Thickness and Remaining Ligament (Observed Flaws under Weld Overlay in C iter 25% of Base hietal)

Weld hiin. Remaining Design Overlay Ligament Thickness 24B R-13 0.4" 0.20" 12AR H 3 0.46" 0.25" I 12AR J 3 0.5 " 0.26" I

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9.0 CONCLUSION

S I 4 The inspection and repair activities at Hatch Unit I during the Fall 1991 outage were performed in accordance with the requirements of NUREG.0313, Revision 2. The inspections, design, and weld overlay activities are discuss.ed in detail in this report. Based upon the above discussion, several conclusions can be drawn regarding IGSCC mitigation g activities at Hatch. These are:

l 1. Weld overlays are effective in repairing IGSCC susceptible locations, and in arresting existing IGSCC. Weld overlays have been in service at Hatch 1 since early 1983, and i l UT examinations of portions of the base metal under the overlays show only minor changes in flaw character. Such changes may be due, in part, to improvements in l inspection techniques.

2. All weld overlays applied during 1991 (six total) meet or exceeded the design requirements. and therefore all qualify as NUREG 0313 " Standard Weld Overlay" repairs.

3. Weld overlay shrinkage stresses may be sufficiently high in 12 inch welds that, combined with other sustained stresses, total sustained stresses may exceed the 1.0 S. criterion of NUREG-0313 for effectiveness of stress improvement processes. If future flaw evaluations need to be performed for 12 inch locations, no residual stress benefit due to IHSI may be assumed for such highly stressed locations. No evaluated locations in piping larger than 12 inch diameter exhibited combined sustained stresses greater than 1.0 S., so IHSI may still be considered effective for these locations.

I 4. The cumulative effect of all overlays applied to the recirculation and associated systems at Hatch is insignificant with regard to the design piping analysis and the operability of supports and pipe whip restraints.

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5. Embedded flaws identified in some overlays are acceptable for continued operation without repair, based upon evaluation in accordance with ASME Section XI, IWB 3500.

lg 6. The hydiogen water chemistry system at Hatch is effective in eliminating IGSCC

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growth when the system is operating. Even normal water chemistry was favorable l during the past cycle, since excellent chemistry was achieved.

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7. Although inspection results yielded some flaw characterizations which were different r from those previously reported, the differences are generally not considered to be significant. Apparent growth may be due in fact to improved inspection techniques,

! including ihe use of automated techniques, rather than actual flaw growth.

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10.0 REFERENCES

I l 3 1. NUREG 0313, Revision 2, " Technical Report on Material Selection and Processing E Guidelines for BWR Coolant Pressure Boundary Piping" Revision 2, January 1988.

-g 2. StructuralIntegrity Associates Report," Contingency Weld Overlay Designs for Hatch 5 Unit 1" SIR-91039, Resision 0, June.1991.

I 3. StructuralIntegrity Associates Report," Contingency Study Regarding the Effects of Additional Weld Overlays at E. I. Hatch Unit 1", SIR 90-044, Revision 0, July 11, 1990.

4. GE Stress Report, " Plant Piping Analysis Design Memo 170-113", September 26, 1984.

I 5, Structural Integrity Associates, pc-CRACK, Version 2.0, August,1989.

6. ASTM Special Technical Publication 756 " Stainless Steel Castings", November 1980.

Page 43. ,

7. ASME Section XI, IWB 3500. 1986 Edition.

8. EPRI " Induction Heating Stress Improvement", EPRI NP 3375, November 1983.

.I 9. - EPRI," Assessment of demedies for Degraded Piping", EPRI NP-5881 LD, June 1988 l

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I I

lI I

l SIR-91-077, Rev. 3 42

,g l

-srnocrunn.

. INTEGRITY

-l_ ASSOCIATESINC

x _a -....u - . = .. ,a _ a.s a._.,,wo __za _ , . _,_ e o a.21.,m a, , s ,i , _ _ _ _ ,a.,. ,u. rn, ,-,___w. ,, _ , -,., _,, ,

4 LI  :

I .

I

'I APPENDIX A l-Weld Overlay Design Drswings I

I I .

I I

I I .

g SIR-91-077, Rev. 3

- staucrona INTEGRITY I. ASSOCIATESINC

I FLOW A  ! B  ;

I i .

4s-my j ,

/; ' -  ;;;lilf %iW" ~ & L w '

T-

c <

1 Scie-end Pipe

] l

. dwsw Not to Scale

E

~

mw DESIGN DBfENSIONS I. WEID NUMBER CHARACTERIZATION t l Al B COhBN  :

i t-

. . , i ,

1B31-1RC-2SB-2 .Assu2ned 360

• Cire. 0.52" 4.0" 4.0" overlay Thickness  ;

100% throughwall revised.

flaw -

wgumwa % % e;o@sne%<<  % bce s %cgi.u , - nm in;: ss/g :r%1w %b enew -

i i

Overlay dimensions b,ased 1

hM l0 l NCC. /C/A.2[8/ /df2I* f on as-built thickness.

f (f4]

O hfl 91 Q7* l$f/ '

Revision Prepared by/ Date Checked by/ Date Approv:d by/ Date COhniENTS yy. ,

1 -

3 .

Job No: Plant /T.' nit GPC M STRUCTURAL

,a File No:

Georgia Pow r company INTEGRITY

.E GPCO-20Q401 Plant Hatch Unit I k/ ASSOCIATES, INC. -

l o==argco.,g7

Title:

standard w:1d Overlay Design  ! Sheet1 of 2 I

I .

I NOTES -

I 1. Weld wire matextal is to' be type ER30SL, with as-deposited delta ferrite content greater than 7.5 FN.

2. Component surface is to be ernmined by dye penetrant method and accepted as clean prior to overlay application in order ,

,'l to include the entire deposited overlay thickness in meeting the  ;

design thickness requirernent, per NUREG-0313. Revision 2.

I

3. In the event that the original component surface does not pass I the note 2 requirements, the first deposited weld layer is to be evamined by dye penetrant method and accepted as clean before

. proceeding with subsequent layers.

l I 4. First weld layer is to have a measured delta ferrite content l greater than 7.5 FN. This requirement does not apply to the final weld layer.

-l

5. Design thickness includes no allowance for surface conditioning l operations to facilitate UT inspections.

I 6. Design length is that required for structural reinforcement; y greater length may be required for effective Ur inspection. This is ,

E to be determined in the field.  !

l l ,

1. D#*

c P ant / Unit

, m . ~

STRUCTURAL cPco-200 Georgia Power Company INTEGRITY

F11e No: Piant Hatch Unit 1 J GPCO 20Q-101 / ASSOCIATES, INC.

I oa"'ns %o: gco.2, ritie: sianaere weia overiar oesign hueet2 or 2 LI

) ,

I p l" FLOW

=

A B = -

I

-I 45 ' MLN TYP b I l

[ '

t Pipe Pipe Q WELD Not to Scale WELD NUMI1ER MW _ b COMMENTS CHARACTER 12NI10N t A B i 1E11-1RHR 20B-D4 ud3 '

o,3ca 3.0" 3.0" flaw

,, 4 I .

~

I ~

l o 114 Meki & ene 2 2 hki Revision Prepared by/ Date Checked by/ Date Approved by/ Date COMMEhTS

• Plant / Unit ceco 20q ..-STRUCTURAL We No:

oeorgia Power company L INTEGRITY Plant Hatch Unit 1 GPCO-20Q401 k/ ASSOCIATES, INC.

ra #

Title:

Standad Weld Overlay Design Sheet 1 of 2 20Q13 1 M

I NOTES I A. Wdd wire materdal is to be type ER308L. with as-deposited ddta ferrite content greater than 7.5 FN.

j 2. Cornponent surface is to be examined by dye penetrant  ;

method and accepted as clean prior to overlay appilcation in order ]

to include the entire deposited overlay thickness in meeting the j g

design thickness requirement, per NUREG-0313. Revision 2.

i

3. In the event that the original cornponent surface does not pass

.l the note 2 requirernents, the first deposited weld layer is to be examined by dye penetrant method and accepted as clean before j g proceeding with subsequent layen. 1

'I 4. First weld ?ryer is to have a measured delta ferrite content l

pt .ater than 7.C FN. This requirement does not apply to the Onal weld layer.

I 5. Design tidelmess includes no allowance for surface conditioning operations to facilitate IJr inspections.

6. Design length is that required for structural reinfortement; greater length may be required for effective Ur inspectiort 'Ihis is l to be determined in the Deld.

!I l Job bo:

q Plant / Unit STRUCTURAL Georgia Power Company ,

INTEGRITY

l.

File No:

3 Plant Hatch Unit 1

,/ ASSOCIATES, INC.

l ko.39qy 3

Title:

Standard Weld Overlay Design Sheet 2 of 2 I 4

, - - - . - - . . ~ -_ - . _ . . ,c..

I I

1

=

A >; B I i l 1 1~ '7 x

[

W 20B-D:4h%N . .

~

P1pe - ,

Valve -

mN m I 1 lInconel

. Butter Butter-Valve I l Interface Not to Secde I FLOV DESIGN DBENSIOrJS COhBENTS WELD NUMBER CHARACTERIZAT10N t A B Assumed 360' Cire. 0.33" Note 1 3" I 1E111RHR-20B D 5 100% throughwall flaw I  ;

. . + . .. ~

I a ll4 +Ie CV> & a>> 2, A ==n-l 2 }lb t'l1bl $$b ofy(m di/) ulyhy @L l 1 Hh att h t 8%/> nhls dw% nNw M = ~~

o lllhfo/ttl9I hd/f/'/h hkb 6flk7i Revision Prepared by/ Date Checlied by/ Date Approved by/ Date COhBENTS

1. ** Plant / unit ceco-20q Q STRUCTURAL Georgta Power Company L INTEGRITY l File No:

GPCo-200401 Plant Hatch Unit 1 k/ ASSOCIATES, INC.

r*"eg g,,,,4 nee: Stamana wad Overiny nesign hbeet or 2 1

l NOTTJ I 1. Blend repair into adjacent repair on weld 20B.D-4. Follow contour of transition with all weld layers. Repair should h!end into valve body I transition at an angle of 45 degrees or less with the component surface. l

Weld overlay material is to be type ERN!Cr-3.

3. Component surface is to be examined by dye penetrant method and accepted as clean prior to overlay applicadon in order to include the entire deposited overlay thickness in meeting the design thiclawas  :

requirement, per NUREG 0313. Revis;on 2.

I 4. In the event that the original component surface does not pass the note 3 requirements, the first deposited weld layer is to be enmined by I dye penetrant method and accepted as clean before proceeding with subsequent layers.

5. Design thiclness includes no allowance for surface condluoning operations to facilitate I.TT inspections.

6. Design length is that required for stnictural reinforcernent; greater length may be required for efective UT inspection. ' nits is to be determined in the fleid.

7. On the valve side of the weld, the inspection volume shall include I the outer 25% of the girth weld and the Inconel butter, and shall extend approx.1" beyond the carbon steel valve - Inconel butter interface.

8. Final structural evaluation and disposition shall be performed using as-built weld overlay dimensions. Pre- and post- overlay contours are to be provided for use in evaluation and disposidon, I

I

^

1. D" Plant / Unit cPcmon cecrgia Power company A[ STRUCTURAL INTEGRITY I File No:

PCM&1 Plant Hatch Unit 1 f > ASSOCIA'IES, INC.

Dmwing N Standard Weld overlay Design Sheet 2 of 2 g g

Title:

I

I I I I

'l l l d

I '

L -- A l

B (Note 1) 4 l 45' MIN M f y l p,

t ,/ .f l .

/

l npe l safe-end I l e wsu3 Not to Scale weto nuunzR cogr yon -

DESIGN DIhm.NSIONS t A B I ID31-1RC 12AR-G4 p 3C

• Cim. 0.2G" 2.0" NA

,l na.

l 4 I

I 1 1/4/o/u/w 4 A u A r/w dh/"ne d"

"Je'"odtA%on I o }lth 6lein E f7 w t w 0flds/s/v Revision Prepared by/ Date Checked by/ Date Appmved by/ Date COMMENTS I #D# Plant / Unit cPCO-20Q STRUCTURAL l Mle No:

GPco-20Q@l Georgia Power company Mant Hats M 1 INTEGRITY k,./ ASSOCIAES, MC.

I """1ngnog,9q,, .nue: standard weld overlay Design sheet 1 or 2 I

l NOTES  ;

1. Blend trpair into tmnsition.  ;

2. Weld overlay wire is to be type ER308L. with as-deposited delta fentte content greater than 7.5 FN. l I 3. Component surface is to be -mmined by dye penetrant method and accepted as clean prior to overlay application in ortler to include the entire depasited overlay thickness in meeting the

'g design thickness requirement, per NUREG-0313 Revision 2.

4. In the event that the original component surface does not piiss g

the note 3 requirements, the first deposited weld layer is to be examined by dye penetrant method and accepted as clean before proceeding with subsequent layers.

I 5. First weld layer is to have a measured delta ferrite content greater than 7.5 FN. This requirernent does not apply to the final l layer.

6. Design thickness includes no allowance for surface conditiordng operations to facilitate UT inspections.

I 7. Design length is that trquired for structural reinforcement; l greater length may be required for effective UT inspection. ' Ibis is to be determined in the fleid.

I Lg < .

1. D" Plant / unit ceco. coq STRUCTURAL l File No:

GPCO 20Q401 ocorgia Power cornpany Plant Hatch Unit 1 INTEGRITY

,/ ASSOCIATES, INC.

l Drawing N g 943g

Title:

Standard Weld overlay Design beet _ 2 of 2

g ,

l .

l 1,

A d B --

l

=

I l (Note 1) 45' MIN TYP / l g

[ , , /'

l l Pipe safe-end I d wem Not to Scale MW DESON DBENSIONS WELD NUhmER _ CohBWUS CHARACTER 12NDON t A B I 1B31-1RC-12BR E4 mne 3

• Cire. 0.2T 2.0" NA l naw g , , . . .

l .

l 1 k]k IblU)9I 0]22 x/> s/91 6 drTh i nevtsed to show sate ena transitson l 0f1 (,);rl9( h S/lll'i/ (lttf9I Revision Prepared by/ Date Checked by/ Date Approved by/ Date , COhBUNTS

                         # D * ' ceco-20q                                 Pl" t/U"!t Q STRUCTURAL l                   Flie No:

GPCO.2@01 ceorgia Power company Plant Hatch Unit 1 L INTEGRITY k,/ ASSOCIATES, INC. l ora *a^;g,,33 ritie: standard weid overuy Design sheet i or 2 l

l NOTES

1. Blend repair into transition.

i l 2. Weld overlay wire is to be type ER308L, with as-deposited delta ferrite content greater than 7.5 FN. I '

3. Component surface is to be evamined by dye penetrant l method and accepted as clean prior to overlay application in ortler to include the entire deposited overlay thickness in meeting the 4 design thickness requirement, per imRCO-0313. Revision 2.

I lu the event that the original component surface does not pass I 4. the note 3 requirements, the first deposited weld layer is to be examined by dye penetrant method and accepted as clean before proceeding with subsequent layers.

5. First weld layer is to have a measured delta ferrite content greater than 7.5 FN. his requirement does not apply to the final l layer.

l G. Design thickness includes no allowance for surface conditioning operations to facilitate UT inspections. I 7. Design length is that required for structural reinfortement; greater length may be required for effective UT inspection. H is is to be determined in the fleid. I I D "

• ceco. coq Fl'"t/t ' t G STRUCTURAL l **"

GPCO 20Q401 Georgia power cornpany Plant Hatch (Jnit I INTEGRITY ky d ASSOCIATES, INC. l D'** * $!co.coass

Title:

standard weld overlay Design sheet 2 of 2 I - -

I . I I '

                                                             ; l; A                  B-      2 l

l (Note 1) g 3s-ny .'^ l

                                                                            ,[

7 t [ > ?8/; a , l Pipe l' Safe-end Q WELD Not to Soate sw DESIGN DmiENSIONS COhniENIS CHARACIIRIZA'IlON t A B l 1B31-IRC-12DR-A4 mne 3 *

t. 0.27" 2.0" NA g ca.

g E 1 f Ieft3f9( /f)If'7I /ff>f4( $ on 0 Y $fli %l bNhlf o' 6!!?9l Revision Prepared by/ Date Checked by/ Date Approved by/ Date COMME?CS I J b No: Pla t/ Unit GPCO 20Q A STR CTURAL l l We No: GPCO-20Q401 Georga Power Cornpany Plant Hatch Unit 1 "L INTEGRITY k,,,,/ ASSOCIATES, INC. l D'** Ih3p Tttle: standard weld Overlay Design , sheet 1 of 2 I L

NOTZ$

1. Blend rtpair into transition.

I 2. Weld overlay wire is to be type ER30SL, with asdeposited delta ferrite content greater than 7.5 FN.

3. Component surface is to be evnmined by dye penetrant method and accepted as clean prior to overlay application in order to include the entire deposited overlay thickness in meeting the l design thickness requirement, per NUREG-0313, Revision 2.

l 4. In the event that the original component surface does not pass the note 3 requirements, the first deposited weld layer is to be examined by dye penetrant method and accepted as clean before I proceeding with subsequent layers. I 5. First weld layer is to have a measured delta ferrite content 1 greater than 7.5 FN. ' Ibis requirement does not apply to the final I layer.

6. Design thickness includes no allowance for surface conditioning operations to facilitate UT inspections.

7. Design length is that required for structum! reinforcement; l greater length may be required for efective UT inspection. ' Itis is to be determined in the field.

                                                 ~

Job No: Phnt/ Unit l File No: GPCO-20Q401 GeorEta Power Company tI A[ STRUCTURAL INTEGRITY

                                                                                                           / ASSOCIATES, INC.

Drawing No: ll ! GPCO 20Q42

Title:

Standard Weld overby Design heet 2 of_ 2 l l l

i

I APPENDIX B .

I General Electric Plant liatch Unit 1 Crack Arrest Verification (CAV) System I I , I 1 I I I LI l I . SIR 91077, Rev. 3 I I- --.-.--._ _ _ _ - _ _ _ _ _ _ _ - - _ _ _

T i. L f p p, . .:D Le: 13 9 111 1 P.00 Dt C 171991 t' at h:letory sAsa-523-147-1291

    -                                                                   DRP 137-0100 December 1991
         ~

PLANT HATCll UNIT 1 CRACK ARREST VERIFICATION (CAV) I SYSTEM

SUMMARY

REPORT TUEL CYCLE 13 Report periodt June 1990 to September 1991 Prepared byt kb I I l i Don llala, Lead Engineer Haterials Monitoring & Structurhl Analysis Services Verified by-  ! i 4.9 172/v/9 / Kevin D'ias "

                                                                    '  I Haterials Monitoring & Structural Analysis Services I                                         -

l %r l2/9I Approved by -- I S.Ranganath, Harfager Materials Honitoring & Structural Analysis Services (I I I HATRT.P03.WP1.0 I I

1.0 INTRODUCTION

I A Crack brest Verification (CAV) system was installed at Plant Hatch Unit 1 in 1988/89. The system contains three crack growth specimens, has electrochemical potential (ECP) neesurement capability and accor.modates inputs from Plant I Hatch water chemistry instrumentation. The system is connected to an existing recire water chemistry sample lins with flow being returned to the RWCU system. A separate autoclave is provided in the CAV for ECP measurements. Copper / Copper Oxide, Silver / Silver Chloride, I and Platinum reference electrodes and Type 304 and 316HG working electrodes are installed in this autoclave. In addition, the ECP autoclave itself (Type 316 stainless steel) is used as a working electrode. The CAV system also accepts inputs from the existing Plant Hatch Dissolved oxygen Monitor and Conductivity Monitor to I allow these primary system water chemistry parameters to be included in the CAV data base. I The CAV system began operation on Nover.ber 16, 1989. Information covering this initial period of operation was suraarized in a previous report (1). The present report covers operation of the CAV system during fuel cycle 13 I only.

2. 0 RESULTs 2.1 General I Pertinent parameters for the three specimens included in the CAV system are auraarized in table 1.

Table 1. Crack Growth Test Specimen Details Specimen Material Condition Stress Intensity Sensitized I- S5-144 T-304 Stainless Steel (1200F, 16 hrs) 20 ksiVin SS-126 T-316HG Simulated Wald 20 Stainless Steel Sensitigation kaiVin (1200F, 1 hour) I INC-76 Alloy 25 182 ksiVin I

 .I

    ,                                                      iEL N:.            Ot: !!.M 11:42 F.04 I

2.2 crack Grovth i The crack langth versus Elapsed Time data for the three crack growth specimens are shown in Figures 1, 2 and 3. Each of those three figures is divided into regions representing I normal vator chemistry (NWC) and hydrogen vator chemistry (HWC) operation periods. Note that the key operating parancters changed nany times over fuel cycle 13, these different operational regions are identified in Appendix A. 2.3 Water chenistry/rcP . The electrochemical potential (ECP) data are summarized in Figure 4. The solid line in Figure 4 represents the data from the Type 304 stainless steel working electrode. The I other symbols represent the data from the ECP autoclave itself. It should be noted that this vessel is nade from Type 316 stainless stasi and is grounded to the Plant Hatch I primary piping compared to the Type 304 Working electrode which is isolated from the plant piping. I Figurc 5 summarizes the hydrogen injection rate into the Plant Hatch Unit 1 primary system, these values represent corrected values which take into account calibration shifts observed by plant personnel and the subsequent corrections l r.ade in the plant data base. The reactor recire water dissolved oxygen and conductivity I data for this time period are shown in rigures 6 and 7, respectively. Note that these signals are provided to the cAv system from existing Plant Hatch Unit 1 instruments.

3. DISCUSSION 3.1 Effact of Hydrocen Water cheristry on crack Grovt_h.

I The crack growth data from the velding alloy 182 specimen (Figure 1) show a clear effect of hydrogen injection on I crack growth. Figure 8 is an expanded view of the data from Figure 1 which shows the distinct change in slope which occurs shortly after the start of hydrogen injection in I August 1990 (T = 799 hours). The steady state crack growth rate

• drops a f actor of =20 beginning shortly af ter the start of hydrogen injection.

I *The ran e on growth rate shown in all figures represents a 3 sigma nterval about the mean value. In statistical terms I this means that there is a =99.9% confidence that the actual value falls within this interval.

I rigure 9 shows the data frc~ the two stainless steel I ' specimens covering this sas.. time period. Here there is no distinct difference between the INC (i.e. 200 part/ billion oxy enated vater) and WC (Hydrogen Water Chemistry) per ods. However, the growth rate, even in the }NC environtent is very low in both stainless steels and is, in fact, near the I ' . limits of detectability of the potential drop technology. For example, the grovth rates represented in rigure 9 correspond to less than 1 mil of measured crack nextension I over the 800 hour duration of the initial NWC region (i.e. 1 mil in 800 hours is =11 mil / year). Existing SCC models (otHE PLEDGE) would predict a grovth rate of about 32 mil / year I depending on tae value of conductivity assu: red. It is, therefore, somewhat unexpected to see growth rates this lov for these two materials. Figure 10 is an expanded view of another region of the data from Tigure 1 covering a tice period =2400 hours later when hydrogen injection is stopped. While interruptions in I hydrogen injection have oc',urred, the specimens at this point in time have accumuhted over 1700 hours of HWC exposure. The nominal grov h rate for this alloy 182 I material under WC conditiens has now dro,pped another factor of ~10 to a nominal 2 mil / year value. Thts suggests that for this material, while there is an immediate decrease in SCC growth rate as coon as Hvc begins, additional decreases l occur the longer HWC is maintained. The data from the two stainless specimens in this same time I region was examined and found to oc inconclusivo in terms of any detectable differences in crack growth rates due to the WC-to-WC transition. An example of another WC/NWC transition is shown in rigures 11, 12 and 13. Here the response of the three materials is l scen in the March / June 91 time frame where the plant operated under NWC conditions for over a month. HWC resumed for about one week, was suspended for =2 weeks and then reestablished again for 6 weeks. Once again, the alloy 182 crack growth (Tigure 11) tracks the changes in water chemistry almost immediately. Distinct I decreases in slope are seen each time HWC is initiated. The growth rates observed under long term INC are still less that those observed during initial NWC exposure suggesting I that there is some lingering benefit of exposure to HWC. I I ...

TEL N:, Ie: ;3.r: ; ; :,: 3 p,tg I' I Extensive GENE laboratory experienct with alloy 102 crack growth specimens has shown that the potential drop technique tends to underpredict crack growth, in some cases by as much as a factor of 2. This is due to the interdendritic nature I of the alloy 182 fracture surface and the inherently uneven, multiplanar geometry. This geometry leaves patches of unbroxen material behind the primary crack front which I evidently continue to conduct current thereby producing a potential drop reading normally associated with a shorter crack. Therefore, it is likely that the true NWC growth rates in the alloy 182 are even greater than those I calculated in these figures. If this is the case, then the absolute amount of crack growth mitigated by HWC is likely to be even greater than the values calculated in the present figures would suggest. The Type 304 and 316NG stainless steel data (Figure 12 and I 13) are still exhibiting very low growth rates *both in NWC and NWC. However, there now appears to be a slope difference between the NWC and MWC regions, but once again the rates are very low and the varianco on the slopes very large. ICP Considerations. I Electrochemical Potential (EcP) is the primary criterion used to assess the degree to which HWC protection is naintained. The EPRI guidelines specify that the ECP be I naintained at -250 av SHE or lower for full HWC protection. The Plant Hatch Unit 1 CAV system uses a Type 304 stainless steel working electrode and a copper oxide reference electrode as the primary means for making this measurement. l Also included in the CAV ECP electrode complement is a platinum reference electrode which allows the ECP to be independently checked. The ECP vessel itself is also used as I. a working electrode to allow an ECP measurement to be made which represents the grounded recire piping system itself. I Table 2 is a sur. mary of CAV ECP measurements made over Puol cycle 13. The 304 stainless steel / platinum values were calculated based upon an assumed value in the recirc system se of 100 part/ billion hydrogen. This value is not actually I measured at Plant Hatch but a 100 ppb value is reasonable based upon experience at other BWRs. Also shown in table 1 is the vessel ECP referenced to the copper oxide electrode l , and the hydrogen injection rate associated with the l individual readings. I I .,.

TEL N:. Oe: !!.9; 1;: 40 P.0" I I Table 2. Plant Hatch Unit 1, Puel C)cle 13, ECP Results (all values tv6HE**) I Test Hours T304/N T304/pt* Vessel /Cu Hydrogen Injection (sefm) I S00 900

                     +78
                   -175                                 -202 N/A  +71
                                                                        -208 0(NWC) 16 1200         -371                                 -402            ~401                                     22 I      1700 6100 8750
                   -477
                   -466
                   -191
                                                        -491
                                                       -397
                                                       -298
                                                                        -424
                                                                        ~409 16 16
                                                                        -312                                     16 Replaced copper oxide ret t 9049 I      9550 10000
                   -310
                   -213
                                                      -312
                                                      -262
                                                                        -251
                                                                        -123 16 12 10251        -291                                -317             -195                                     16

• Calculated for an assumed 100 ppb hydrogen level.

         ** SHE = Standard Hydrogen Electrode I

I These results, and tb.a more comprehensive plot of these data in Figure 4, indicate that full protection was achieved at 16 sern until late in the fuel cycle when the vessel (i.e. ground) reading drifted out of protection. This is I consintent with previous experience at other INRs Vhich indicates that late in the fuel cycle, more hydrogen must be injected to maintain the ECp levels previously achieved earlier in the cycle at lover levels. Table 3 represents a sur. mary of the entire fuel cycle in terms of CAV availability ar.d amount of time on HWC. I I. Table 3. plant Hatch Unit 1, Puel Cycle 13, CAV/HWC Operating Surmary. I Total duration, fuel cycle 13 (June 1, 1990 to September 18, 1991) 11376 hours Total time CAV on line 8866 hours Total time CAV&HWC on line 4691 hours l HWC Availability 4691 / 11376 = 41% I  ! l

l TE!. N:. :e: ;?.M 11:45

• 05 I

4.0 strXXARY The CAV system at Plant Hatch Unit i has provided date which support the following conclusions:

1. Inplementation of hydrogen veter chemistry (WC) has resulted in significant decreases in stress corrosion crack grovth in alloy 182 from rates as high as 138 mil / year prior to WC to very low growth rates af ter long periods of time on WC.

I ,

2. When WC is suspended, the alloy 182 growth rates increase again, although not to their former pre-HWC values.

These new values are on the order of 19 mil / year.

3. over the last several thousand hours of the fuel cycle, the alloy 182 post-WC growth rates are much lower than I those seen in the pre-HWC period. However, they do appear to be increasing with time. This may be an indication of a residual benefit to the long exposure period to HWC

                                       -conditions.

4. The growth rates naasured in either the sensitized Type 304 stainless steel or the simulated weld sensitized Type I 316 NG stainless steel were very lov and ,therefore, displayed significant variability. It was not possible to detect significant differences in growth rate between the l HWC and nornal water chemistry (NWC) conditions. This any be due to the excellent water chemistry control (lov vater conductivity) seen during the current fuel cycle.

I 5. The ECP levels measured during the current fuel cycle, at hydrogen injection levels of 16 scfm or greater, were sufficient to achieve full protection until late in the fuel , E cycle. This was true for the isolated Type 304 stainless

3. steel electrode as well as the grounded Type 316 stainless steel ECP vessel.

6. Although the NWC system was on line 414 of the time, the alloy 182 crack growth data, showed significant reductions in crack growth. This suggests that a substantial amount of I crack propogatic.: vas avoided even though HWC was only on line for part of the operating time.

5.0 REFERENCES

1. D. Hale, " Plant Hatch Unit 1, CAV Progress Report #1",

GENE Report SASR-91-04, January 1991. I t

M M M M M M M M M M M M M M M M

                                     .91
                                                                                                                                        -~
                                     .30      -
        ,                   m C      --l~

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O IW 2000 ^ 3000 4000 5000

                                                                                                                           ^     '    ^  '  - l 6000     7000      8000      segg IN II m HOURS Figure I. Plant Hatch Unit I CAY Crack length Versus Time Data Stress Intensity 25 kst/in.                                       , Fuel Cycle 13, Alloy 182, Specimen IfvC-76,

M M M M M M M M M M M M M M M M M M M t

                          .75 r,

C ns nfp-e- .n ~=I-w.! "? *

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0 1000 2000 3000 4000 5000 6000 7000 0000 9000 20000 11000

• HOURS 4

Figure 2. Plant Hatch Unit I CAY, Crack tengtfi Versus Time Data. Tuel Cycle 13, Type 304 Stainless Steel (sensitized), Specimen 55-144, Stress Intensity 20 ksi/in. __ ___ 1

M' EEE W " M " " " "" " " m um um uma m BEE ME E'E

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O teen aoea anoo 4een sono coao ,cco occo 3,,, ,,,,, ,,,,, r HOURS n.. I,: Figure 3. Plant Hatch Unit I CAY, Crack length Versus Time Data, Teel Cycle 13, Type 316MG Stainless Steel. Tgecimen S5-126. Stress Intensity 20 ksi/in.

T51. No. De: 13.91 11:n s .:: I* iga .

                                                                      '*394 lf v6 C..

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                                                                             .     ...t_--                                              8 F                  8000                 ettt            sitt              ettt                lt000                            ttttC HOU815 itssto oisss! *:: c.,

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                                         ,1 0                                      1           5       0 g    a .. ,                         .               .                    .               .                  .                        .

• tees seee sees sees seece stece I HOURS Figure 4. Plant Hatch Unit 1 cAV, Electrochemical Potential (ECP) Data, Fuel Cycle 13.

I G 6

c w ~ t_ r 50 , n E 40 - h. U U1 - v Z O 30 - s F-U U 5 .'. z - Y 20 - Z w _ L _ _ _ _ _

   .O                                                                        l O                                                                          -

tr - j Q y 10 - I , j-t i i _ s. . g . . . 0 2000 4000 6000 8c00 10000 32000 i HOURS Figure 5. Plant Hatch Unit 1, Hydrogen Addition Rates, ruel Cycle 33.

2 M M M M M M m mm m m m m M M M 'M 200 . r, -

       .O                                          .

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                                                                                                                                                            .o sa HOURS                                                                      -

i l t. n 1 Figure 6. Plant Hatch Unit 1 CAV, Dissolved Oxygen Data, Fuel Cycle 13 ,

M M M M M M M M M M M M M

                .35 E                                                                                .

O N .30 - M C 0 E O  !

               .25     -                                                                              .

to O , r-O . r L E .20 - u 5 > , s t-s .15 l.

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8 - ' O 2000 4000 E000 000a Ic000 - 12003 HOURS I 9 Figure 7 .. Plant flatch Unit 1 CAV, Conductivity Data, Fuel Cycle 13.

VEL No. De: 13 91 11:49 F.lf I ' I .882 da/dt = 135/138 mil / year HNC I n .B?? -

                                                                    \

da/dt = 15 5/25 mil / year I y b 2 .en - E l M U I U .667 - da/dt = 187/196 mil / year I .662 0 100 200 300 400 500 600 700 Be3 920 1800 HOURS Figure 8. Plant Hatch Unit 1 CAV, Expanded View of Alloy 182 Crack Length Versus Time Data Tor Initial Application of Hydrogen Water Chemistry. I . _ _ . . - -

TLL No. De 13 91 11149 F.1' Type 316HG S.8. ta/st = 3 H.S tf ma/rw . g

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• 3 T-8 H EU/ test I ,,,,

9 IM 4H 4M i i SM 1988 e . IIM l'M i - I HOURE I .P4# Type 304 S.S. I ge/st . 0 34 164 mn/ pear

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I lam (nuen.Hi trogen 4/1/M r I ,3, 8 fts 4N GM BM 1944 1890 14M HOURS l Figure 9. Plant Hatch tJnit 1 CAV, Expanded View of Type 304 I and 316HG Stainless Steel crack I,ength Versus Time Data For Initial Application of Hydrogen i Water Chamistry. I . _ _ , _ _ _ _ , _ _ , , _ _ _ _ . - - - - - - - ~ - ' - - - ^ - - - " ~ ~ " ~ ' - -

f .u ..v. re, .:.r4 4..;. . .I - I I '

                     .sts

,I de /et = 16/19 mil / year - n .888 - s I I N I e

                  .J
                     .887 -
                                                                    /

NHC I x ,i de/dt =_14/16 mn/yeer

                     .e86 -

W y {l HNC jes/dt = 0 21/3 3 mil / year

                     .ses                                                     '

I 2500 3000 3500 4ccc 4500 5ccc HOURS I I - I Figure 10. Plant Hatch Unit 1 CAV, Expanded View of Alloy 182 Crack Length versus Time Data For Tina l Period After Resumption of Normal Water Chemistry, October / November 1990. , I

l-I. I

              .E                                                        E                          E 4                                       M             A               E          A          h          'E          %

d E E E d d e

    'l                                                     1             1               I          I          I             I          I da/dt =_ f,46-6.2 t .!!/ year I.C   +888           -

Iu , da/dt

• 46.2-49.6 mH/ year Is d 'Hyc e

I HYC HTC y Iy j ,/ ,. // h / I

                                      /

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           .935                                                    '                      '              '

I sett stes 7ste tste it648 HOURS I . I I Figure 11. Plant Hatch Unit 1 CAV, Expanded View of Alloy 182 Creek Length Versus Time Data For Time Period After Resumption of Normal Water Chemistry, March / June 1991. 4

l -

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            .743                                                     !                l                 l                    l            l l

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                               . . (l'."

da/dt = 0 62-1.42 m!!/ year da/dt = 0.84-4.7 mil / year

           .741                               '                                            i sete                          8500              roos                      7500                                                          i 3e88                   8598 I                                                                    HOURS I                                                                                                                                                 '

I Figu!*e 12. Plant Hatch Unit 1.CAV, Expanded View of Type 304 Stainless Steel Crack Length Versus Time Data For I Time Period After Resumption of Normal Water Chemistry, March / June 1991. I .

                                                                                                                                            -        1

j. TEL No. Dec 13 91 11:51 P.21

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C .733 .

rr.

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> '

U - da/dt = 0.32-1.26 mil / year !I

              ;                              de/dt = 3.1-7.2 mil / year (l      .,,,

sets ssee rete 7ses sees HOURS

I Figure 13.

Plant Match Unit 1 CAV, Expanded View of Type i 316HG Stainless Steel Crack Length Versus Time Data For Time Period After Resumption of Normal Water.Chemintry, March / June 1991. i

 .l                                                                     -x-

t I Appendix A, Tuol Cycle 13, Operating History. Region Start Stop Remarks (Test (Tost Hours) Hours) N/A 6/1/90 6/29/90 I Plant startup to begin Tuol cycle 13, Normal Water Chemistry (WWC) operation I 1 6/29/90 (0) 8/1/90 (798) Start CAV system, operation on NWC I 2 8/1/90 (799) 8/9/90 (984) Started hydrogen addition 9 16 SCFM. 3 8/9/90 8/15/90 Started Zinc addition, (985) (1128) hydrogen increased to 22 SCTM 4 8/15/90 8/27/90 Continued Zinc, hydrogen to (1129) (1418) 18 SCTM 5 8/27/90 '8/31/90 Isolated ECP vessel to * (1419) (1516) replace reference electrode 6 8/21/90 9/12/90 Continued Zinc, hydrogen (1517) (1812) dropped to 16 SCFM I 7 9/12/90 9/14/90 continued Zinc, returned to (1813) (1844) NWC 8 9/14/90 9/15/90 Continued Zinc, addition of (1845) (1869) hydrogen resumed e 8 scrM 9 9/15/90 9/21/90 Continued Zinc, returned to (1870) (2023) NWC l 10 9/21/90 9/27/90 Continued Zinc, addition of [ (2024) (2160) hydrogen resumed 6 12 SCFM I I 11 9/27/90 (2161) 10/4/90 (2332) Centinued Zinc, addition of hydrogen increased to 16 SCFM I I I I

TEL No, dec139111:52 P.23 I Appendix A, (continued) 12 10/4/90 10/22/90 Continued Zinc, returned to (2333) (2762) NWC, two startups during I 13 10/22/90 11/7/90 interval Continued Zinc addition of

        ,,     (2763)        (3119)          hydrogen resume,d 0 16 SCm 14      11/7/90       12/6/90          Continued Zinc, yeturned to (3150)        (3852)          WC 14a     12/6/90       .i.2/7/90        Special 14 hour hydroga.n (3853)         (3B64)          injection test I   15       12/7/90 (3865) 1/16/91 (4823)

Resumed WC operation I 16 1/16/91 (4824) 1/26/91 (5058) CAV out of Service I 17 1/26/91 2/12/91 Continued W C operation I (5059) (5473) 18 2/12/91 2/25/91 CAV out Of Service (5474) (5791) 19 2/25/91 2/27/91 Continued WC operation (5792) (5936) 20 2/27/91 3/7/91 CAV out Of Service (5837) (6025) 21 3/7/91 3/12/91 Resumed addition of hydrogen (6026) (6149) @ 16 SCm 22 3/12/91 3/20/91 Resumed WC operation (6150) (6340) 23 3/20/91 4/4/91 CAV out Of Service (6341) (6703) - 24 4/4/91 4/15/91 Resumed NWC operation (6704) (6963) I 25 4/15/91 (6964) 4/21/91 (7116) Resumed addition of hydrogen

                                           $ 16 SCW I

I g -22

TEL No. Dec 13.91 11:53 P.24 I Appendix A, (continued) l 26 4/21/91 5/4/91 Resumed W C operation (7117) (7416) I ,27 5/4/91 (7417) 6/12/91 (8364) Resumed addition of hydrogen e 16 scrM 28 I 6/12/91 6/14/91 l (8365) Flant shutdown (8400) 29 6/14/91 6/17/91 Resumed W C operation (8401) (8466) , 30 5/17/91 6/20/91 Resumed addition of hydrogen (8467) (8539) i 16 SCTM 31 6/20/91 6/21/91 . Resumed WC operation (8540) (8565). 32 6/21/91 6/26/91 (6566) Resumed addition of hydrogen (8682) 0 16 SCFM 33- 6/26/91 6/26/91 Resumed W C operation (8C83) (8692) 1 34 6/26/91 7/1/91 Resumed addition of hydrogen (8693) (8799) 0 16 SCFM 35 7/1/91 7/11/91 Resumed addition of hydrogen (8800) (9049) S 8 SCFM 3 -36 7/11/91 7/16/91 CAV out of service (9050) (9174) g 37 7/16/91 8/9/91 Resumed addition of hydrogen 3 (9175) (9750) 9 16 SCFM 38 8/9/91 i O/13/91 Plant shutdown (9751) (9845) 39 8/13/91 8/26/91- Resumed addition of hydrogen (9846) (10143) 6 12 scFM 40 8/26/91 8/27/91 Resumed W C operation (10144) (10167) I I y . TEC No. ' Dec 13.91'11:53 P.25 4 l Appendix A, (continued)

!           41 8/27/91    9/10/91        Resumed addition of hydrogen (10168)    (10517)        8 16 SCTM 42 9/10/91    9/18/91        CAV out of service           '

j

             , (10518)    (10696)

$ 43 9/18/91 Plant shutdown to begin (10696) refuel outage iI

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