ML14041A178

Attachment 1 - Response to Request for Additional Information for Alternative Request IR-3-17, for ASME Section XI for Repair/Replacement of Class 3 Service Water System Valves

ML14041A178
Person / Time
Site:	Millstone
Issue date:	02/06/2014
From:	Dominion Nuclear Connecticut
To:	Office of Nuclear Reactor Regulation
References
13-596
Download: ML14041A178 (68)

Text

Serial No.13-596 Docket No. 50-423 ATTACHMENT I RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR ALTERNATIVE REQUEST IR-3-17, FOR ASME SECTION XI FOR REPAIR/REPLACEMENT OF CLASS 3 SERVICE WATER SYSTEM VALVES MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.13-596 Docket No. 50-423 Attachment 1, Page 1 of 5 In a letter dated March 28, 2013, Dominion Nuclear Connecticut, Inc. (DNC) requested approval of Alternative Request IR-3-17 to permit certain degraded valves in the service water system to remain in service until they could be replaced. The affected valves have now been replaced. In a letter dated October 22, 2013, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) to DNC related to the alternative request. This attachment provides DNC's response to the NRC's RAI.

Question I Figure 5 of the Surry report shows a micrograph of a Surmy valve which experienced selective leaching and was subsequently destructively analyzed. In this figure approximately 50 percent of the area appears to be occupied by phases not subject to selective leaching. In this micrograph the non-selectively leachable phases appear to be continuous. Given the apparent continuity of the non-leachable phases, the NRC suspects that this sample will retain at least some strength even when fully leached.

Alternatively, if the leachable phase was continuous, the NRC suspects that little or no strength would remain in a fully selectively leached specimen. Minor changes in chemistry or processing conditions of a component may significantly change the amount of each phase present. The NRC is aware that the Millstone valves have received a heat treatment which the Surry valves did not. The NRC is also aware that some heat treatments should reduce the formation of leachable phases while others increase the formation of leachable phases. The significance of such a treatment relative to chemistry differences between the valves remains unclear to the NRC. Given the apparent tenuous balance between continuous and discontinuous phases in the Surry valve and the chemistry and processing differences between the Surry and Millstone valves, please justify why it should be assumed that the non leachable phase is continuous in all locationsin all valves at Millstone.

DNC Response The information provided in the relief request regarding the dealloying and mechanical properties of the Millstone valves was based on information from the Surry report and information known about the materials used for the valves at Millstone. Since then, the subject valves have been replaced and have been sectioned and metallurgically examined. The results that were observed for MPS3 are summarized in Attachment 2.

A review of the micrographs indicates that the non leachable phase appears as white and is continuous in the etched micrographs. Elemental dot maps were prepared for one sample of each size valve for aluminum and iron, pages 23 and 56 of Attachment 2.

These two pages illustrate that distribution of aluminum is continuous in these microstructures. In addition, the dot maps illustrate that the leachable phase is discontinuous in the area examined. Weepage was observed on at least one valve, which indicates there are locations where the leachable phase is continuous to provide a path for the water.

Serial No.13-596 Docket No. 50-423 Attachment 1, Page 2 of 5 Microprobe analysis was performed on four valves in different areas to determine the change in percent aluminum as a result of the dealloying. This work is summarized on pages 26, 27, 57 and 58 of Attachment 2. The percent aluminum varied from approximately 7% on the inside diameter (ID) (dealloyed) to approximately 10.50% on the outside diameter (OD) (specification nominal).

Metallurgical work was also performed on a number of as cast valves removed from MPS3. This work is summarized in Attachment 3. A review of the micrographs from the metallurgical work indicates that the leachable phase is continuous in the as cast sections examined. This is consistent with what is known for C95400 material not given any heat treatment, i.e. as cast.

A review of the micrographs in Attachment 2 of the 1200'F temper material indicates that the leachable phase tends to be discontinuous. This is consistent with the literature that the temper only heat treatment doesn't eliminate the leachable phase but does reduce the amount of the leachable phase and the phase tends to be discontinuous.

Question 2 Figure 1 to enclosure 1 to the relief request (p 14 of 56) shows a graph of the tensile strength of samples taken from the Surry valve. These test specimens are represented as having varying degrees of dealloying. It is assumed that this was estimated optically based on the color change between leached and non leached material. Only one sample tested is represented as being 100 percent dealloyed. One sample is not statistically significant. Please justify why this single value is used as the basis for all structuralcalculations.

DNC Response Although only one 100 percent dealloyed sample was successfully tested, information gathered from the multiple Surry valve samples of varying degrees of dealloying was adequate to determine the tensile strength of 100 percent dealloyed C95400 material.

A total of seven (7) specimens from the Surry valve were used to determine the tensile strength at 100 percent dealloyed (including six specimens between 50% dealloyed and 100% dealloyed). The tensile strength versus percentage dealloyed of the seven (7) specimens was plotted. A trend line was drawn through the lower bound dealloyed samples. This resulted in four points on the trend line and the remaining three points above the trend line. The 100 percent dealloyed sample was the asymptote of the curve. It is noted that the tensile strength of the approximately 80 percent dealloyed sample is the same order of magnitude tensile strength as the 100 percent sample and that another sample point greater than 90 percent dealloyed had a higher tensile strength than the approximate 80 percent dealloyed specimen.

Serial No.13-596 Docket No. 50-423 Attachment 1, Page 3 of 5 The following considerations were not specifically credited within the structural integrity analysis, but are noted here as conservatisms within the overall structural analysis.

Additional conservatism is inherent in the development of the ASME Code allowable stress (which is based on tensile strength) as the Code uses a safety factor of four.

Also, review of the pipe stress analysis results indicates that in the worst case, the pipe stress at the location of these valves is only 85% of the allowable stress determined as described above. Thus, the overall method of tensile strength determination and the inherent conservative approach in determining the actual stresses and allowable stresses provide adequate justification for use of the selected tensile strength.

Therefore, adequate and reasonable assurance has been provided to demonstrate pressure boundary structural integrity.

Question 3 As indicatedin item 2, above, the extent of selective leaching is often identified visually, by color change. Given that selective leaching is a chemical process in which aluminum is removed gradually from the selectively leachable phases, it is possible that the color change associated with selective leaching will occur long before all the aluminum is removed from the leachable phases. In this case a sample of material which is optically judged to be 100 percent leached may still contain aluminum in the leachable phases and may retain more strength than a sample of similar appearance from which all aluminum has been removed from the leachable phases. In order to consider a sample to be 100 percent leached, the NRC believes that it is necessary to demonstrate that the sample is 100 percent visibly discoloredand to demonstrate that all of the aluminum has chemically been removed from the leachable phases. Such a demonstration may involve polishing the end of a broken tensile specimen and chemically examining the polished surface using an electron microscope. In light of the apparent lack of chemical analyses in support of the present data, please explain why the data provided in support of the relief request should be considered to representfully dealloyed material.

DNC Response As discussed in the response to RAI 2, the tensile properties used in support of this relief request are a conservative, lower bound estimate based upon the seven specimens in the Surry report. The metallurgical work performed on the valves of this relief request with the 12000F heat treatment and that performed on the as cast valves supports this assertion.

A visual comparison of the microstructure of the as cast material and the 1200'F heat treatment material shows that the 1200°F heat treatment material has more of the non leachable phase, which is consistent with the literature for C95400 aluminum bronze.

The 1200'F heat treatment does not eliminate the leachable phase but reduces the amount of it as compared to the non leachable phase. Therefore, the mechanical properties of the 1200'F heat treatment material in the valves of this relief request

Serial No.13-596 Docket No. 50-423 Attachment 1, Page 4 of 5 would be at least as good as the as cast material, if not slightly better because of the higher percentage of the non leachable phase. In other words, the tensile properties used in support of this relief request were from as cast material while the actual valves were supplied with a 1200°F heat treatment that increased the amount of the non leachable phase and the increase in the non-leachable phase translates into higher mechanical properties as compared to the as cast material. Therefore the mechanical properties used in support of this relief request are a conservative, lower bound estimate of the actual valve material in the valves in this relief request.

Question 4 The Surry report (Enclosure 2 to the relief request) contains a table of tensile test results. This table reports that several of the specimens tested broke outside the gage marks. Given the design of tensile bars, this indicates the possibility that the measured tensile strengths overstate the actual tensile strengths of the material. Of particular interest is sample M. This sample is reported to be 100 percent dealloyed, to have a tensile strength of approximately 9 KSI, and to have failed in the grips of the tensile test machine. Given the clamping power and resulting friction of the grips, the actual tensile strength of this sample may have approached0 KSI. Given the potentialthat the tensile strength of this sample was much lower than reported,please justify the tensile strength used in the structuralanalysis.

DNC Response There are many potential reasons for grip failure in addition to the cause stated above (e.g. casting flaw, initial misalignment, etc.). Personnel most knowledgeable with the Surry report were contacted, but no insight could be provided on the actual cause of the grip failure. Without more detailed information relating to why any particular specimen failed in grip, the standard approach when compiling data is to exclude failed samples.

The tensile strength used in the structural analysis is based on information gathered from the multiple Surry valve samples of varying degrees of dealloying and the conservatisms as discussed in the response to RAI question 2. Due to the failed test for sample M, DNC excluded the 9 KSI tensile stress from sample M in determining the allowable stress. However, it should be noted that if a 9 KSI tensile stress had been used to develop the corresponding Code equation allowable stresses, the valves would meet the operability allowable stresses, although with less margin than the 15% margin indicated in the response to RAI question 2 above. Therefore, reasonable assurance is provided that the subject valves would continue to meet their functional requirements given the worst case loadings.

Serial No.13-596 Docket No. 50-423 Attachment 1, Page 5 of 5 Question 5 Since there are differences in the heat treatment and chemistry potential differences in continuous vs. discontinuousphases between the Millstone and Surry valves may exist.

The validity of the test data as noted in the sample that failed in the grips and the lack of statisticalsignificance of the Surry data is not conducive to concluding the valves have or will continue to have adequate strength. Additional tensile test data, chemistry data is needed to ensure strength of the materialis adequate for structuralintegrity. Please provide additionalinformation that will demonstrate adequate strength of the valves can be maintained.

DNC Response Two tests have been performed on the MPS3 valves in this relief request that show the valves have adequate strength. First, as included in the relief request, hydrostatic tests were conducted at pressures greater than twice the valve rating. Only the valve that had known weepage produced any drops of water. These hydrostatic tests demonstrated structural capability. Additionally, a bend test was performed on one of the 3" valves removed from MPS3. The test report is provided in Attachment 4. The bend test was done to a stress of 40,000 psi in the pipe, which is well beyond any stress that these valves would experience. The results of the hydrostatic test and bend test demonstrate adequate strength of the valves was maintained.

Serial No.13-596 Docket No. 50-423 ATTACHMENT 2 EXAMINATION OF MILLSTONE UNIT 3 SERVICE WATER VALVES FOR SELECTIVE LEACHING MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

Attachment 2, Page 1 of 61 Work Scope

• A total of eight valves were submitted to the lab. Four were 1.5" valves and the other four were 3" valves.

• Each valve was photographed and then sectioned in half longitudinally every 90 degrees as viewed from the suspected inlet end of each valve.

e The cut faces were then cleaned with a flapper wheel and macroetched to show a rough approximation of the degree of dealloying or selective leaching of aluminum.

• Metallographic cross sections were prepared from the two most affected locations on each valve. The depth of the dealloying was measured from the cross sections in the unetched condition, and then energy dispersive spectroscopy (EDS) was used to determine the weight percent of aluminum in the affected and unaffected areas.

e The cross sections were then lightly etched and photographed.

Attachment 2, Page 2 of 61 1.51 nch Valves Valve 662

Attachment 2, Page 3 of 61 Photos showing the valve labeled on the tag and body as V662. Some verdigris was noted on one side of the valve (arrow upper left photo), apparently from stem leakage. The lower left photo shows the valve after it was sectioned in half lengthwise. The entire inside surface was coated with a dark, uniform coating.

Attachment 2, Page 4 of 61 Additional cuts were made every 90 degrees as looking towards the suspected inlet end of the valve. Photos showing the cross sections from the 3:00 (left) and 12:00 positions after the sections were macroetched in acidified silver nitrate. The internals have been removed from the valve. The dark areas (arrows) indicate where dealloying has occurred.

Attachment 2, Page 5 of 61 Photos displaying the cross section taken through the 3:00 position on V662. There is evidence of light dealloying through the entire cross section as indicated by the dark zones in the upper left photo, and the pink areas in the micrographs to the right. Scale 1/32". Original magnification top right- 15X, bottom 200X. Unetched.

Attachment 2. Paae 6 of 61 Photos displaying the cross section taken through the 12:00 position on V662.

There is also evidence of light dealloying through the entire cross section but it was slightly heavier for 2 mm as indicated by the small, dark voids in the structure shown in the lower right micrograph. Scale 1/32". Original magnification top right- 15X, bottom 200X. Unetched.

Attachment 2, Page 7 of 61 Valve 664

Attachment 2, Page 8 of 61 Photos showing the valve labeled on the tag and body as V664. Some verdigris was seen on this valve. The lower left photo shows the inside of the valve. The entire inside surface of one end of the valve was coated with a dark, uniform coating.

Attachment 2, Page 9 of 61 I

I Photos showing the cross sections from the 3:00 (left) and 6:00 positions after the sections were macroetched in acidified silver nitrate. The internals have been removed from the valve. The dark areas (arrows) indicate where dealloying has occurred.

Attachment 2, Page 10 of 61 Photos displaying the cross section taken through the 3:00 position on V664. There is evidence of light dealloying through the entire cross section as indicated by the dark zones in the upper left photo, and the pink areas in the micrographs to the right. Scale 1/32". Original magnification top right- 15X, bottom 200X. Unetched.

Attachment 2, Page 11 of 61 Photos displaying the cross section taken through the 6:00 position on V664. There is evidence of light dealloying through the entire cross section but it was slightly heavier for 6 mm. The lower right photo shows the transition from the area with fine voids to the lightly damaged zone.

Scale 1/32". Original magnification top right- 15X, bottom 200X. Unetched.

Attachment 2, Page 12 of 61 V665

Photos showing the valve labeled on the tag and body as V665. Some spotty verdigris staining was seen on this valve.

The lower left photo shows the inside of the valve after it was sectioned in half.

One side of the valve was covered with a dark deposit.

Attachment 2, Page 14 of 61 Photos showing the cross sections from the 3:00 (left) and 6:00 positions after the sections were macroetched in acidified silver nitrate. The dark areas (arrows) indicate where dealloying has occurred.

Attachment 2. Pawe 15 of 61 Photos displaying the cross section taken through the 3:00 position on V665. There is evidence of light dealloying through the entire cross section as indicated by the dark zones in the upper left photo, and the pink areas in the micrographs to the right. Scale 1/32". Original magnification top right- 15X, bottom 200X. Unetched.

Attachment 2. Page 16 of 61 Photos displaying the cross section taken through the 6:00 position on V665. There is evidence of light dealloying through the entire cross section. Scale 1/32". Original magnification top right- 15X, bottom 200X.

Unetched.

Attachment 2, Page 17 of 61 V663

Photos showing the valve labeled on the tag 663 but on the body as V662. The outside of the valve was fairly clean. The lower left photo shows the valve after it was sectioned in half lengthwise. Most of the inside surface was coated with a dark coating of deposit that was flaking off in some areas leaving a green deposit.

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Attachment 2, Page 19 of 61 Photos showing the cross sections from the 3:00 (left) and 12:00 positions after the sections were macroetched in acidified silver nitrate. The dark areas (arrows) indicate where dealloying has occurred.

Attachment 2, Page 20 of 61 Photos displaying the cross section taken through the 3:00 position on V663. Dealloying was noted to 4 mm into the cross section as indicated by the dark zone in the upper left photo, and the pink areas in the micrograph above. The micrograph to the left shows undamaged material. Scale 1/32". Original magnification top - 15X, bottom 200X.

Unetched.

Attachment 2, Page 21 of 61 Photos displaying the cross section taken through the 12:00 position on V663.

Dealloying was noted to 4 mm into the cross section as indicated by the dark zone in the upper left photo, and the pink areas in the micrograph above. The lower micrograph shows the transition to undamaged material.

Scale 1/32". Original magnification top - 15X, bottom 200X. Unetched.

Attachment 2, Page 22 of 61

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• Attachment 2, Page 23 of 61 Microstructures (200X Potassium Dichromate Etch)

, Page 24 of 61 Attachment 2, Page 25 of 61 Valve Number Sample Location Depth of Dealloying Percent Aluminum V662 12:00 100%. Heaviest until 2 mm. ID-7.85 Mid wall- 7.69 OD- 7.87 3:00 100%. Light but uniform ID-7.67 dealloying. Mid wall- 7.36 OD- 8.04 V664 3:00 100% Light but uniform iD-8.53 attack. Mid wall- 7.76 OD- 8.66 6:00 100% dealloying. Some voids ID-8.23 seen until 6 mm. Mid wall- 8.71 OD- 9.23

Attachment 2, Page 26 of 61 Valve Number Sample Location Depth of Dealloying Percent Aluminum V665 3:00 100% Light, uniform ID- 8.17 dealloying. Mid wall- 7.97 OD- 8.25 6:00 100% Light, uniform ID- 7.88 dealloying. Mid wall- 7.94 OD- 8.49 V663 12:00 Fairly uniform dealloying 4 ID- 6.54 mm deep. Mid wall- 6.34 OD- 9.16 3:00 Fairly uniform dealloying until ID- 6.57 4 mm. Some voids along IDto Mid wall- 6.97 2 mm OD- 10.53

Attachment 2, Page 27 of 61 3 Inch Valves V658

Attachment 2, Page 28 of 61 Photographs taken of the valve labeled 658 on the valve body and 664 on the tag. Both openings in the valve were heavily encrusted with deposit.

Attachment 2, Page 29 of 61 Pictures showing the cross sections taken from the 3:00 (left) and 9:00 positions after they were macroetched. The dark areas (arrows) are locations where some degree of selective leaching has occurred.

Micrographs taken from the 3:00 cross section. Along the ID surface, the dealloying was heaviest to about 0.6 mm as shown in the upper left photo. The dealloying was continuous for 9 mm and then discontinuous for another 4 mm. The lower photo was obtained in the zone where the dealloying became sporadic. Scale 1/32". Original magnification 50X. Unetched.

Attachment 2, Page 31 of 61 Photo showing the cross section from the 3:00 position and the depth of the dealloying.

Scale 1/32".

17 "zA "assure Result 2 Points 7.319 =

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Micrographs taken from the 9:00 cross section. The dealloying was continuous for 7 mm and then discontinuous for another 4 mm. The lower photo was obtained in the zone where the dealloying became sporadic. Scale 1/32". Original magnification 50X. Unetched.

Attachment 2, Page 33 of 61 Photo showing the cross section from the 9:00 position and the depth of the dealloying.

Attachment 2, Page 34 of 61 V661

Attachment 2, Page 35 of 61 Photographs taken of the valve labeled 661 on the valve body and 661 on the attached tag. Overall, the inside of the valve was relatively free of any heavy deposits.

Attachment 2, Page 36 of 61 Pictures showing the cross sections taken from the 12:00 (left) and 9:00 positions after they were macroetched. The dark areas are locations where some degree of selective leaching has occurred.

Micrographs taken from the 9:00 cross section. Along the IDsurface some shallow pockets of heavy loss were noted. The dealloying was continuous for 13 mm and then sporadic for another 6-7 mm. The lower photo was obtained in the zone where the dealloying tapered off. Scale 1/32". Original magnification 50X.

Unetched.

Attachment 2, Page 38 of 61 Photo showing the cross section from the 9:00 position and the depth of the dealloying. Scale 1/32".

Micrographs taken from the 12:00 cross section. The dealloying was uniform for 13 mm and then discontinuous for another 6-7 mm. The area labeled "A" appears to be through wall but this may be damage from the OD. The lower photo was obtained in the zone where the dealloying became sporadic. Scale 1/32". Original magnification 50X. Unetched.

Attachment 2, Page 40 of 61 Photo showing the cross section from the 12:00 position and the depth of the dealloying. Scale 1/32".

Attachment 2, Page 41 of 61 V668

Attachment 2, Page 42 of 61 Photographs taken of the valve labeled 668 on the valve body and 668 on the tag. Both openings in the valve were coated with green-colored deposits.

Attachment 2, Page 43 of 61 Pictures showing the cross sections taken from the 3:00 (left) and 6:00 positions after they were macroetched. The dark areas are locations where some degree of selective leaching has occurred.

Attachment 2, Page 44 of 61 Micrographs taken from the 3:00 cross section. The dealloying was heaviest with some voids for 2 mm and continuous to 11 mm. The dealloying was sporadic for another 3 mm. Scale 1/32". Original magnification 50X. Unetched.

Attachment 2, Page 45 of 61 Photo showing the cross section from the 3:00 position and the depth of the dealloying.

Scale 1/32".

MMMMMMMMMM

Attachment 2. Paqe 46 of 61 Micrographs taken from the 6:00 cross section. The dealloying was heavy with small voids until 2 mm and continuous to 12 mm.

The damage became sporadic for an additional 4 mm. Scale 1/32". Original magnification 50X. Unetched.

Attachment 2, Page 47 of 61 Photo showing the cross section from the 6:00 position and the depth of the dealloying.

Scale 1/32".

Attachment 2, Page 48 of 61 V873

Attachment 2, Page 49 of 61 Photographs taken of the valve labeled 873. The opening on the bonnet end of the valve was coated with a moderate layer of sediment (right photo).

Attachment 2, Page 50 of 61 Pictures showing the cross sections taken from the 6:00 (left) and 9:00 positions after they were macroetched. The dark areas are locations where some degree of selective leaching has occurred.

Micrographs taken from the 6:00 cross section. The dealloying was heavy (small voids) but sporadic to 1 mm. The dealloying was uniform to 10 mm but sporadic after that to 3 mm. Scale 1/32".

Original magnification 50X. Unetched.

Attachment 2, Page 52 of 61 Photo showing the cross section from the 6:00 position and the depth of the dealloying.

Scale 1/32".

Attachment 2. PaQe 53 of 61 Micrographs taken from the 9:00 cross section. The dealloying was heavy (small voids) but sporadic along the ID.The dealloying was uniform to 9 mm but sporadic after that to 2 mm. The measurements were taken away from the flange face (A). Scale 1/32". Original magnification 50X. Unetched.

Attachment 2, Page 54 of 61 Photo showing the cross section from the 9:00 position and the depth of the dealloying.

Scale 1/32".

Attachment 2, Page 55 of 61 SE3Qkt WD2 mmS6 20 OP a

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• a Elemental X-ray dot map for aluminum (top qU - 9 1.

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Attachment 2, Page 56 of 61 Valve Number Sample Depth of Dealloying Percent Aluminum Location V658 3:00 Heavy to 0.6 mm, continuous to ID- 6.95 9, sporadic for 4 mm. Mid wall- 9.51 OD- 10.16 9:00 Continuous to 7 mm, sporadic ID- 7.38 for another 4 mm. Mid wall- 9.93 OD- 10.31 V661 12:00 Continuous to 13 mm, sporadic ID- 6.80 for 6-7 mm. One area was Mid wall- 10.02 dealloyed through cross section, OD- 10.54 possibly from OD attack.

9:00 Continuous to 13 mm, sporadic ID- 7.00 to 6-7 mm. Mid wall- 9.15 OD- 10.50

Attachment 2, Page 57 of 61 Valve Number Sample Location Depth of Dealloying Percent Aluminum V668 3:00 Heavy but not uniform loss to ID- 7.27 2 mm, continuous to 11 mm, Mid wall- 9.13 sporadic for 3 mm. OD- 10.58 6:00 Heavy dealloying 2 mm, ID- 7.22 continuous to 12 mm, Mid wall- 9.81 sporadic for 4 mm. OD- 10.19 V873 6:00 Heavy but sporadic to 1 mm, ID- 7.88 continuous to 10 mm, Mid wall- 9.11 sporadic for 3. OD- 10.04 9:00 Sporadic heavy loss along ID, ID- 7.83 continuous to 9 mm, sporadic Mid wall- 10.02 to 2 mm. OD- 10.01

Attachment 2, Page 58 of 61 Microstructures (200X Potassium Dichromate Etch)

, Page 59 of 61 Attachment 2, Page 60 of 61 25 Depth of Dealloying in mm 20 J

15 L Sporadic Dealloying

" Continuous Dealloying

" Heavy Damage (Voids) 10 5-0 658 3:O00 658 9:00 661 12:00 661 9:00 668 6:00 668 3:00 873 6:00 873 9:00

Attachment 2, Page 61 of 61 Summary

• The cross sections prepared from the 1.5 inch SW valves revealed light selective leaching had occurred through-wall in 3 of the 4 valves.

e The sections removed from the 3 inch valves showed attack as deep as 20 mm. In one valve, the dealloying appeared to have progressed through-wall but this was apparently due to the combination of attack from the ID and OD.

• Spectrographic testing of the dealloyed areas revealed aluminum content as low as 6.35 wt. %.