NOC-AE-11002766, Supplement to the License Renewal Application

Supplement to the License Renewal Application

ML11354A087
Person / Time
Site:	South Texas
Issue date:	12/08/2011
From:	Rencurrel D South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-11002766, STI: 33136034, TAC ME4936, TAC ME4937, G25
Download: ML11354A087 (49)

Text

Nuclear Operating Company South Texas Prolect Electric GeneratingStation PO.Box 289 Wadsworth, Tcas 77483 December 8, 2011 NOC-AE-1 1002766 10 CFR 54 STI: 33136034 File: G25 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Supplement to the South Texas Project License Renewal Application (TAC NOS. ME4936 and ME4937)

Reference:

1. STPNOC Letter dated October 25, 2010, from G. T. Powell to NRC Document Control Desk, "License Renewal Application" (NOC-AE-10002607)

(ML103010257)

2. STPNOC Letter dated November 21, 2011, from D. W. Rencurrel to NRC Document Control Desk, "Response to Requests for Additional Information for the South Texas Project License Renewal Application Aging Management Review, Set 2" (TAC Nos. ME4936 and ME4937)(NOC-AE-1 1002743)

By Reference 1, STP Nuclear Operating Company (STPNOC) submitted a License Renewal Application (LRA) for South Texas Project (STP) Units 1 and 2. This letter supplements responses to requests for information regarding the LRA. Changes to previous STPNOC responses to requests for additional information in Reference 2, are provided in Enclosure 1. provides line-in/line-out changes to the LRA. provides a new regulatory commitment. There are no other regulatory commitments in this letter.

Should you have any questions regarding this letter, please contact either Arden Aldridge, STP License Renewal Project Lead, at (361) 972-8243 or Ken Taplett, STP License Renewal Project regulatory point-of-contact, at (361) 972-8416.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on 2 &I/ 1_0 1, Date enic rese Senior Vice President, Technical Support & Oversight KJT

Enclosures:

1. Supplemental Responses to RAIs

2. STP LRA Changes with Line-in/Line-out Annotation

3. New Regulatory Commitment 4 k

NOC-AE-1 1002766 Page 2 cc:

(paper copy) (electronic copy)

Regional Administrator, Region IV A. H. Gutterman, Esquire U. S. Nuclear Regulatory Commission Kathryn M. Sutton, Esquire 612 East Lamar Blvd, Suite 400 Morgan, Lewis & Bockius, LLP Arlington, Texas 76011-4125 Balwant K. Singal John Ragan Senior Project Manager Chris O'Hara U.S. Nuclear Regulatory Commission Jim von Suskil One White Flint North (MS 8B1) NRG South Texas LP 11555 Rockville Pike Rockville, MD 20852 Kevin Polio Senior Resident Inspector Richard Pena U. S. Nuclear Regulatory Commission City Public Service P. O. Box 289, Mail Code: MN16 Wadsworth, TX 77483 C. M. Canady Peter Nemeth City of Austin Crain Caton & James, P.C.

Electric Utility Department 721 Barton Springs Road C. Mele Austin, TX 78704 City of Austin John W. Daily Richard A. Ratliff License Renewal Project Manager (Safety) Alice Rogers U.S. Nuclear Regulatory Commission Texas Department of State Health Services One White Flint North (MS 011-Fl) 11555 Rockville Pike Rockville, MD 20852 Balwant K. Singal Tam Tran John W. Daily License Renewal Project Manager Tam Tran (Environmental) U. S. Nuclear Regulatory Commission U. S. Nuclear Regulatory Commission One White Flint North (MS O11F01) 11555 Rockville Pike Rockville, MD 20852

Enclosure 1 NOC-AE-1 1002766 Enclosure I Supplemental Responses to RAI's : Table 1 - ECW De-alloying Data : Table 2 - ECW Weld Crack Data

Enclosure 1 NOC-AE-1 1002766 Page 1 of 15 Supplemental Responses to RAI's

References:

1. NRC letter dated September 21, 2011, "Requests for Additional Information for the Review of the South Texas Project, Units 1 and 2 License Renewal Application -

Aging Management Review, Set 2" (TAC Nos. ME4936, ME4937) (ML112440201)

2. STPNOC Letter dated November 21, 2011, from D. W. Rencurrel to NRC Document Control Desk, "Response to Requests for Additional Information for the South Texas Project License Renewal Application" (NOC-AE-1 1002743)

The following table lists the affected Request for Additional Information numbers from the Reference 1 where the response from Reference 2 stated that STPNOC will provide a response by December 8, 2011. The response is provided below.

RAI Number Reason for Change B2.1.37-1 Response not provided previously B2.1.37-2 Response not provided previously 4.1-6 Response not provided previously Aluminum Bronze (111)

RAI B2.1.37.1

Background:

LRA Section B2.1.37 states that the plant-specific Selective Leaching of Aluminum Bronze program will consist of an external surface visual inspection every six months of aluminum bronze (copper alloy with greater than 8 percent aluminum) components and a walkdown of yard areas to detect changes in ground conditions that could indicate leakage where susceptible buried piping welds are located.

The GALL Report Revision 2, AMP XI.M33, "Selective Leaching," utilizes internal visual inspections and hardness tests (where feasible) or mechanical examination to identify the presence of selective leaching prior to the period of extended operation.

LRA Tables 3.3.2-4 and 3.3.2-27 state that copper alloy (aluminum> 8percent) components which are being managed by the Selective Leaching of Aluminum Bronze program are exposed to raw water or are buried. Raw water and soil environments are subject to change with time, or there may be local environments where degradation may be more adverse than generally expected (e.g., in locations where microbiologically-influenced corrosion (MIC) may be occurring, reference IN 94-59).

LRA Section B2.1.37, "operating experience," does not describe any specific instances of selective leaching of aluminum bronze (copper alloy with greater than 8 percent aluminum) components.

Enclosure 1 NOC-AE-1 1002766 Page 2 of 15 Issue:

The staff lacks sufficient information (e.g., the extent to which selective leaching is known or suspected to have occurred in aluminum bronze components) to conclude that the external surface visual inspections and changes in ground conditions proposed in LRA Section B.2.1.37 would be sufficient to detect selective leaching on internal surfaces of aluminum-bronze components prior to a loss of the components intended function. This is of particular concern given that the internal raw water and buried environments can change and therefore the rate of selective leaching may not be constant over time.

Request:

1. Revise LRA Sections B2.1.37, Selective Leaching of Aluminum Bronze Program, to:

a. Include periodic internal visual inspections coupled with mechanical examinations (e.g.,

hardness testing, destructive examination) capable of detecting the degree of selective leaching occurring in aluminum bronze components in order to establish a baseline understanding of the extent to which subsurface degradation has occurred to date and to monitor and trend this aging effect throughout the period of extended operation (based on a review of plant-specific operating experience, opportunistic inspections may suffice).

b. State when baseline inspections will commence (e.g., ten years prior to the period of extended operation).

c. Based on a review of plant-specific operating experience related to selective leaching of aluminum bronze components, state the minimum number of inspections that will occur both prior to and during the period of extended operation.

Alternatively, state the basis for why the external surface visual inspections and changes in ground conditions proposed in LRA Section B.2.1.37 would be sufficient to detect selective leaching on internal surfaces of aluminum-bronze components prior to a loss of the components intended function.

2. For each instance of aluminum bronze selective leaching that has been identified:

a. Characterize each by date and where the defect was discovered (e.g., weld, casting, forging).

b. Identify which had sufficient metallurgical examination to determine the full extent of de-alloying, and state the results of those exams (e.g., penetration depth, circumferential and axial span, and location of affected area).

c. For each instance of selective leaching which did not have sufficient metallurgical examination to determine the extent of de-alloying, state what is known regarding the defect configuration, (e.g., whether they are radial or axial, dimensions, exposure time).

Enclosure 1 NOC-AE-l 1002766 Page 3 of 15 STPNOC Response:

1.a. STP does not plan to perform internal visual inspections of Essential Cooling Water (ECW) system piping and components. The internal pipe wall is not susceptible to de-alloying and the field welds, which are susceptible to de-alloying, are covered by backing rings. Thus any de-alloying in the underground piping is not visible internally. Extent of de-alloying can only be determined by destructive examination of the component in the lab. STPNOC will re-establish the earlier program to perform destructive examinations of through-wall de-alloyed components. If components are identified as leaking during the ten-year period prior to the period of extended operation, then a destructive metallurgical examination of one leaking component per unit will be performed. Preference in selecting the component to be destructively examined will be given to a leaking weld with a backing ring that would be similar to the welds in buried ECW wrought aluminum bronze piping. If no leaking components are found during this period, destructive examination will be performed on the current inventory of leaking components that were removed from service prior to this period.

If leaking below-grade welds are discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination.

LRA Appendix A1.37, B2.1.37 and Table A4-1 have been revised to require destructive examinations of through-wall de-alloyed components. Enclosure 2 provides the line-in/line-out revision to LRA Appendix A1.37 and B2.1.37. Enclosure 3 provides the line-in/line-out to LRA Table A4-1.

1.b See response to 1.a.

1.c As described above in the l.a response, two components (i.e. one per unit) will be destructively examined in the ten-year period prior to the period of extended operation. If components leak during the period of extended operation, up to an additional four leaking components (two per unit) will be destructively examined during the period of extended operation if through-wall leaks are observed.

If leakage from below grade welds is discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination. As explained in response la above, internal inspection of buried aluminum bronze piping provides no benefit. Testing and analyses have shown that 100 percent de-alloyed components are structurally adequate to withstand the maximum stresses that may occur in the buried ECW system. The degree of de-alloying can not be monitored during periodic surface inspections except as identified in components that are destructively examined in the lab.

2.a Tables 1 and 2 (see Attachments 1 and 2 to this Enclosure) provide discovery dates and component types. De-alloying has occurred in aluminum bronze castings, weld repair areas in extruded aluminum bronze tees, and in welds with pre-existing inside diameter cracks. No de-alloying of wrought aluminum bronze piping has been found. South Texas Project (STP) licensing submittal (STP Letter No. ST-HL-AE-2748, dated November 1, 1988) evaluates multiple occurrences of aluminum-bronze de-alloying in small bore socket welded castings.

Small bore socket welded castings have been replaced with wrought aluminum bronze.

Tables 1 and 2 do not include the de-alloying identified in the 1988 letter.

Enclosure 1 NOC-AE-1 1002766 Page 4 of 15 Several above-grade welds have exhibited through-wall leakage (e.g., Table 1, items 15 and 37 and Table 2). All but two of these welds had a through-wall crack that originated from a pre-existing inside diameter weld crack behind a weld backing ring. The two welds without a pre-existing crack were fabrication repair welds at the end of an extruded tee and located adjacent to the pipe-to-tee butt weld.

2.b Tables 1 and 2 provide a short summary of each available lab report. Extent of de-alloying was determined by examination of a specimen that was mounted, polished and etched in the laboratory. The de-alloyed component was typically cut into one, two or three axial rings and each ring section was divided into eight or more specimens. The circumferential extent of de-alloying at each of the eight or more specimens was examined. Plots and/or tables showing circumferential extent of de-alloying at each axial location are provided in the reports.

2.c Tables 1 and 2 provide information where lab tests were not obtained. No information on extent of de-alloying is available without results from lab tests.

RAI B2.1.37-2

Background:

SRP-LR Revision 2, Section A. 1.2.3.4, "Detection of Aging Effects," states that the detection of aging effects should occur before there is a loss of a component's intended function and that the parameters monitored or inspected should be appropriate to ensure that the intended function will be adequately maintained.

LRA Section B2.1.37, "scope of program" program element states that the applicant has analyzed the effects of de-alloying and found that degradation is sufficiently slow such that rapid or catastrophic failure is not a consideration. The LRA "scope of program" program element also states that leakage can be detected before a flaw reaches a limiting size that would affect the operability of the essential cooling water system. STP updated final safety analysis report (UFSAR) Appendix 9A states that the temporary non-code conditions are justified for operability in accordance with fracture mechanics and limit load methods consistent with ASME Code, Section Xl methodology.

Issue:

1. The staff lacks sufficient information to determine the anticipated continued progression of de-alloying during the period of extended operation.

2. During the audit, the staff reviewed a calculation that determined the critical bending stress for pipe failure as a function of through-wall crack length for a postulated crack in an aluminum bronze pipe weld, AES 92021630-1Q. The staff also reviewed a calculation for circumferential through-wall de-alloying in aluminum bronze castings, AES 93061964-1Q (ML003742174).

Given that material properties (e.g., fracture toughness, tensile strength) are expected to degrade due to de-alloying, it is not clear to the staff:

Enclosure 1 NOC-AE-1 1002766 Page 5 of 15

a. Whether the fracture toughness properties used in both calculations were obtained from de-alloyed specimens.

b. Whether tensile strength properties used in the first calculation were obtained from de-alloyed specimens.

c. How the fully de-alloyed flow stress value was derived for the second calculation.

3. Given that both of the above calculations were modeled based on the de-alloying configuration being crack-like, the staff lacks sufficient information to determine that the methodology of the calculations is sufficient to demonstrate operability of the components if the de-alloying progresses in a uniform or layer-like manner, thus impacting a larger area of the component. In addition, the program does not address trending of inspection results against the analysis results to ensure that impacted component current licensing basis (CLB) function(s) will be met.

4. The staff lacks sufficient information to conclude that the USFAR Appendix 9A flooding, reduction in flow, and water losses from the essential cooling pond analyses envelope the potential degradation that could occur throughout the period of extended operation and, therefore, cannot conclude that the leak from a component will not impact the CLB function of the essential cooling water system components or other in-scope components.

5. During the audit, the staff reviewed a calculation that evaluated the capability of the station to detect leakage in buried essential cooling water piping. Based on the calculation methodology and assumptions, it does not appear to the staff that the analysis included the potential for leakage to preferentially travel down the interface between the soil and pipe nor along compaction seams. In addition, the staff lacks sufficient information to determine that the ground level surface is soil, versus stone or a paved surface, in all locations where there are susceptible buried welds. Given this, the staff cannot conclude that the detectability is as low as stated.

6. LRA Section B2.1.37, "acceptance criteria" program element states that components with visible signs of leakage are evaluated and scheduled for replacement by the corrective action process. The staff believes that, given the degree of subsurface de-alloying that could occur before and during the period of extended operation, the program should include periodic internal visual inspections coupled with mechanical examinations (e.g., hardness testing, destructive examination) capable of detecting the degree of selective leaching occurring in aluminum bronze components (see RAI B2.1.37-1). In order to evaluate the effectiveness of the program, the staff needs to understand the acceptance criteria of the periodic internal inspections.

Request:

1. Based on plant-specific information provided in the response to Request 2 in RAI B2.1.37-1, state the maximum expected subsurface degradation that could occur throughout the period of extended operation prior to the pressure boundary being penetrated by a de-alloying layer.

2. Regarding calculations AES 92021630-1Q and AES 93061964-1Q, state:

Enclosure 1 NOC-AE-1 1002766 Page 6 of 15

a. Whether the fracture toughness properties were obtained from de-alloyed specimens, and if not, what is the basis for the calculation's assumed value.

b. Whether tensile properties were obtained from de-alloyed specimens for the first calculation, and if not, what is the basis for the calculation's assumed value.

c. How the fully de-alloyed flow stress value was derived for the second calculation.

3. Given that both of the above calculations were modeled based on the de-alloying configuration being crack-like, respond to (a), (b), or (c), and (d) below:

a. State the basis for why the methodology of the calculations is sufficient to demonstrate operability of the components if the de-alloying progresses in a uniform or layer-like manner, thus impacting a larger area of the component, or

b. Provide an analysis that uses the worst case uniform or layer-like de-alloying that could occur through the period of extended operation, or

c. State the basis for how a potential transition to uniform or layer-like de-alloying will be detected, and update the UFSAR Supplement for the Selective Leaching of Aluminum Bronze program to reflect this basis and that an analysis will be conducted to reflect the worst case uniform or layer-like de-alloying that could occur during the period of extended operation.

d. State how periodic internal visual inspections coupled with mechanical examination results will be trended against the results of existing analyses to ensure that the rate of degradation is understood and there will not be a loss of a component's CLB function(s).

4. In relation to the flooding, reduction in flow, and water loss from the essential cooling pond analyses of UFSAR Appendix 9A:

a. State the basis for why the medium energy break size flaw stated in UFSAR Appendix 9A is larger than the maximum size flaw for which the piping can still perform its CLB function, and

b. State the basis for why only one through-wall, and not multiple through-wall defects, is acceptable in analyzing the impact of flooding, reduction in flow, and water loss from the essential cooling pond.

5. State the basis for why potential for leakage from buried ECW piping will not preferentially travel down the interface between the soil and pipe or along compaction seams, or revise the calculation to account for this phenomenon. In addition, state the basis for being able to detect leakage where the ground level surface is stone or paved in locations where there are susceptible buried welds.

6. State the following acceptance criteria that will be used during the periodic internal inspections (see RAI B2.1.37-1):

Enclosure 1 NOC-AE-1 1002766 Page 7 of 15

a. Degree of de-alloying that will result in an expansion of the scope of internal inspections beyond that submitted in the response to RAI B2.1.37-1.

b. Degree of de-alloying that will result in replacement of an affected component prior to visually detecting external leakage.

STPNOC Response:

1. South Texas Project (STP) licensing submittal ST-HL-AE-2748, dated November 1, 1988 (Attachment 2, page 27 of 58), addresses de-alloying rate studies. R. J. Ferrara and T. R.

Caton (Materials Performance [February 1982]) have reported a maximum de-alloying rate of 30 mils per year (mpy) after one year and 22.5 mpy after two years. These rates are lower than the 44 mpy average and 83 mpy maximum estimated at STP. This maximum rate for STP is based on the assumption that de-alloying for a small sample of castings occurs in three years to 100 percent of the wall and the average rate assumes 50 percent.

De-alloying is a phenomenon where aluminum in one of the microstructure phases selectively corrodes leaving the balance of the matrix intact. The through-wall de-alloyed surface appears as a porous surface. The Essential Cooling Water (ECW) pipe material used at STP is SB-315 (conforms to SB-169 CA614 Annealed Seamless) for pipe sizes 10 inches and under, and welded SB-169 CA-614 for pipes above 14 inches in diameter.

Initially, STP did not observe de-alloying in aluminum-bronze piping or welds resulting in weeping. This is consistent with literature showing that alloys with less than 8 percent aluminum (wrought pipe and weld metal) are resistant to de-alloying. STPNOC is still identifying de-alloyed components; however, occurrences are less frequent. The previous de-alloying rates thus are very conservative.

STPNOC anticipates de-alloying will continue during the period of extended operation. The maximum de-alloying that could occur prior to the pressure boundary being penetrated is essentially 100 percent of a full cross section. That is an analyzed condition as discussed below in response to item 3a. STPNOC intends to continue implementing the mitigation strategy (described in UFSAR Section 9A - in particular the discussion on "compensatory action" that begins on UFSAR page 9A-5) that will provide continued safe and reliable operation of the ECW system while maintaining structural integrity of the system so that the system meets its intended function during the period of extended operation.

2a. The fracture toughness properties are not obtained from de-alloyed specimens. The basis for the values used is described below. The first of the two calculations identified in the question addresses flawed welds (cracks) and the second addresses de-alloyed castings.

No other vulnerable areas have been identified in aluminum-bronze ECW piping at STP.

Calculation AES-C-1630-2 (APTECH Project No. AES92021630-1Q)

This calculation determines the critical bending strength for a circumferential through-wall crack in the aluminum-bronze pipe welds per ASME Section Xl Appendix H methods for flawed piping as guidance. The property of the pipe material is specified as ASME SB-169 Grade CA-614. The strength of the fracture toughness properties of aluminum-bronze weld metal is referenced from previous test data of aluminum-bronze butt welds (Ref. Structural Integrity Analysis of ECW Lines (STP);

Calculation AES8303381, Rev. 1, dated July 1983). The fracture toughness tests were

Enclosure 1 NOC-AE-1 1002766 Page 8 of 15 Crack-Tip Opening Displacement (CTOD) tests performed on welded samples of Alloy C614 specimens of 6-inch, 10-inch and 30-inch diameter pipe as well as 30-inch diameter field welded pipe.

The statistical sample was intended to characterize a bound on the worst expected defect size in the inaccessible welds. There were no signs of de-alloying corrosion in either the weld metal or the wrought aluminum-bronze pipe. The results from tests described above (

Reference:

Table 4-1 in Calculation AES-C-1630-2) were used in the calculations. Also, assumption 2 in the calculation states - "Effects of de-alloying on bulk weld metal properties are assumed to be negligible."

Calculation AES-C-1964-1 (APTECH Proiect No. AES 93061964-1Q)

This calculation determines the critical bending stress for failure by plastic collapse or by fracture of aluminum-bronze casting as a function of through-wall de-alloying length and/or through-wall crack length. The critical bending stress is the failure stress (i.e. the ultimate bending load capacity) without a safety factor.

In 1988, STP also observed weeping-type leaks in the two inch and smaller ECW piping.

These leaks were attributed to de-alloying corrosion going through the wall of the cast valve or cast fittings. Only castings had signs of de-alloying. The materials of interests were SB-148 CA 954 (10 - 11.5 percent aluminum) used for cast aluminum-bronze valve bodies, and SB148 CA 952 (8.5 - 9.5 percent aluminum) used for cast aluminum-bronze fittings. The critical stress intensity factor (Kic - fracture toughness) was determined through CTOD testing. The CTOD tests were run on two valve bodies (valve body material CA 954 alloy). The relationship between critical bending and de-alloyed area was determined for two limiting conditions: (1) a complete 360 degree circumferential de-alloyed region originating from inside surface; and (2) a through-wall de-alloyed region extending partly around the circumference. The methodology and test results were submitted to the NRC via licensee letter ST-HL-AE-2748 dated November 1, 1988.

The de-alloyed region is conservatively modeled as a region not capable of carrying any load. The structural capacity of the casting is determined by a limit load analysis.

2b. The tensile strength used in calculation AES-C-1630-2 (APTECH Project No.

AES92021630-1Q) for pipe material ASME SB-169 Grade CA-614 is a yield strength of 32 ksi and a ultimate strength of 72 ksi. The impact of de-alloying is not considered because pipe material is not susceptible to de-alloying.

2c. For the purpose of calculating the limit load of a pipe, Article H-5320 of Appendix H to ASME Section Xl is used. The flow stress is the average of the specified minimum yield and ultimate strengths. The strength properties for SA-952 alloy from the ASME codes are used.

The flow stress for SA-952 casting (in which material is not de-alloyed) is calculated as 45 ksi.

When only de-alloying was present (no cracks), the de-alloyed material is conservatively modeled as not having any load carrying capacity. This is accomplished by imposing a cut-off limit at the point where the structural strength of a fully de-alloyed section is reached. The flow stress for fully de-alloyed SA-952 casting is reduced to 30 ksi.

Enclosure 1 NOC-AE-1 1002766 Page 9 of 15 Table 2.5 in STP letter ST-HL-AE-2748 has tensile strength test data for de-alloyed (samples ranged from 11 to 100 percent de-alloyed) castings class CA-954.

3a. STPNOC chooses to answer item (a), from among (a), (b), and (c).

The methodology of the calculations discussed in this RAI is not sufficient to demonstrate operability in cases of uniform or layer-like de-alloying. However, STPNOC performed other calculations in addition to the two calculations discussed above. Specifically, STPNOC calculation RC-9890 reanalyzed all underground ECW piping assuming 100 percent de-alloyed material. De-alloyed material loses more than half its initial strength, but retains substantial residual strength even when fully de-alloyed. Actual testing of de-alloyed specimens established the residual tensile strength as 30 ksi. Calculation RC-9890 demonstrates that most underground sections of pipe meet Code allowable using 30 ksi material. Even those locations and stress combinations that do not meet the Code allowable are shown to maintain structural integrity using the limit load method of analysis.

Since the calculation assumes 100 percent de-alloyed material, it bounds the worst-case uniform or layer-like de-alloying that could occur to demonstrate operability during the period of extended operation.

3d. STPNOC does not perform internal visual inspections. Therefore, there will be no trending of inspection results. As stated in the response to item 3a, 100 percent de-alloyed material has been analyzed and shown to be capable of maintaining structural integrity. Therefore, the rate of degradation is not an important parameter and does not need to be trended.

4a. True critical crack size, in the context of fracture mechanics, is dependent on pipe stress. A relatively small crack may be critical in a highly stressed pipe, but that same crack may be less-than-critical size in a pipe subjected to lower stresses.

The "critical" flaw size mentioned in UFSAR Appendix 9A is not a true critical flaw size. It is an approximate opening size established as a rectangle one-half the pipe diameter by one-half the pipe thickness regardless of loading on the pipe. This conveniently-calculated opening size is used for flooding analysis. It is referred to as a critical flaw size, but it is different from a true critical crack length established by fracture mechanics.

4b. The impacts of flooding, reduction in flow and ECP water loss are addressed separately.

Flooding - Flooding is only relevant above the ground surface. A single leak large enough to potentially pose a flooding concern would be detected almost immediately. Surface leakage above ground will not be allowed to progress to the point of having multiple undetected leaks of significant size.

Reduction in Flow - - As stated in the UFSAR, section 9A, a loss of more than 1000 gallons per minute (gpm) in a single train would be needed to impact the cooling function of the train. The threshold for detection of a single leak is established as 10 gpm. This means more than 100 undetected leaks in a single train would be needed to cause loss of adequate cooling capability. This scenario is not credible for several reasons:

Enclosure 1 NOC-AE-1 1002766 Page 10 of 15

• Most underground piping is straight and relatively free of fittings and corners compared to above-ground piping. Therefore, underground piping is less susceptible to de-alloying. The relative scarcity of vulnerable locations underground makes the simultaneous occurrence of more than 100 undetected leaks very unlikely.

" The normal makeup to the Essential Cooling Pond (ECP) is 500 gpm (from well water) which is sufficient to overcome evaporation and seepage losses. The pond level is maintained in a narrow range between 25.5 feet and 26.0 feet and is checked daily. Inability to maintain pond level above 25.5 feet triggers a six- hour plant shutdown action statement per South Texas Project Units 1 and 2 Technical Specification 3.7.4. If total losses (seepage plus evaporation plus unidentified leaks in all six trains) exceed the normal makeup capability of 500 gpm, the pond level will drop. This would be readily noticed and investigated.

• De-alloying is a very slow process.

• It is not reasonable to postulate 100 independent leaks of 10 gpm or less in one train.

The amount of undetected leakage that could occur in a single train is substantially less than 500 gpm. The makeup capability of 500 gpm, reduced by seepage, evaporation and leaks in the other 5 trains, is the maximum leakage that could exist undetected in a single train.

Thus, it is not reasonable that the 1000 gpm threshold for loss of adequate cooling flow in a single train would be reached.

Water Loss from the ECP - - The pond is sized to maintain at least a 30-day supply of water without makeup. The design does not account for leaks but does conservatively overestimate seepage and evaporation losses. As described in Section 9.2.5.1.1.5 of the UFSAR, the design value for seepage is 1.2 cubic feed per second (540 gpm). A pre-operation study using historical weather data concluded the maximum monthly evaporation would be 500 gpm and the maximum daily evaporation would be 750 gpm. The pond is sized to sustain losses of more than 1,300 gpm (540 gpm seepage plus 750 gpm evaporation) without makeup for at least 30 days. Actual operating experience has shown much lower losses than used in design. Actual losses were measured in 2000 and 2005 as 0.30 cfs (135 gpm). The pond volume is 342 acre-feet (111 million gallons). At a loss rate of 1000 gpm, the pond would have more than a 60-day supply of water, which is double the minimum requirement given in Reg. Guide 1.27. A very substantial increase in loss rate would be needed to reduce the pond inventory to less than a 30-day supply. Since losses in excess of 500 gpm exceed makeup and are therefore immediately detectable due to declining pond level, underground leakage would not remain undetected and would not result in an unacceptable water loss from the ECP.

5. Most of the underground piping is 15 feet below ground, which is roughly 5 feet below the water table. Following installation of the ECW underground lines, safety-class compacted structural backfill was installed above the pipes. Small air voids are possible, but the combination of 15 feet of soil overburden pressure, compaction, quality control for installation of safety-related backfill and submergence below the water table make existence of a preferential leakage travel path of significant length highly unlikely. If such a path did exist, a pressure head would be required to drive flow along the path. This pressure head could only result from a dome of water building above the leak location, which is exactly the condition postulated in the calculation of the threshold of detection at the surface (10 gpm).

Enclosure 1 NOC-AE-1 1002766 Page 11 of 15 The calculation assumes a homogenous porous soil medium. Lack of homogeneity could either slow or accelerate the rise of water to the surface, but would not fundamentally alter the process by which detection would eventually occur. The calculated 10 gpm detection threshold is recognized as being an approximate value. Since it is such a small portion (i.e., one percent) of the flow loss needed to imperil cooling capability, more precise calculations that account for non-homogenous soil conditions have not been performed.

A thin layer of gravel exists only at the surface throughout the Protected Area. The gravel does not significantly impede detection because it is very porous. Water rising up to the gravel layer will flow downhill along the ground surface sloping toward storm drainage catch basins. The water would be visible at the catch basin. Inspection of catch basins near the path of underground ECW piping is part of the inspection program that looks for underground leakage. STP operating experience includes several underground leaks involving potable water and fire water that were detected at the surface. This proves that the gravel does not prevent surface detection of underground leaks.

The distance from the ECW intake structure to the STP Unit 1 Mechanical Auxiliary Building and Diesel Generator Building is about 1000 feet, and the return distance to the ECW discharge structure is roughly 1500 feet for a total underground distance of roughly half a mile. The distance to and from STP Unit 2 is approximately 1000 feet more. Only a small portion of this travel path is paved. The piping crosses underneath some fairly narrow plant roads. Surface detection is impeded somewhat in these localized areas, but only over a very small area. Leakage of 10 gpm or greater that continues for several weeks will affect a wider area and will be detected. The calculation for detection threshold established that a 10 gpm leak into homogenous soil will bring water to the surface within 30 days and a leak of 14 gpm would bring water to the surface within one day. Capillary action was conservatively neglected in this calculation. Leaking water moves in all directions, including upward and continues to move outward and upward as long as the leak continues. Thus, local pavement could delay detection by several days, but does not alter the conclusion that underground leakage of 10 gpm or greater would be detected at the surface. The delay in detection of leakage is not critical due to the slow growth of de-alloying.

Each unit has an Outage Control Center building located over underground ECW piping. In order to facilitate detection in this area, a perforated pipe is installed above the ECW pipes and below the floor slab for the building to collect leaking water and route it to a nearby catch basin. Thus, detection is enhanced in this area, in that leakage not quite sufficient to rise to the surface will make it to the below-grade collection pipe and be detected.

6.a. Periodic internal inspections are not performed. Only periodic surface inspections for evidence of through-wall leakage are performed. STP testing and analyses have shown that 100 percent de-alloyed components are structurally adequate to withstand the maximum stresses that occur within the underground ECW system. The degree of de-alloying is not determined during the periodic surface inspections.

6.b Components are replaced or repaired whenever through-wall leakage is discovered.

Degree of de-alloying can only be determined by destructive examination of the component in the lab.

Enclosure I NOC-AE-1 1002766 Page 12 of 15 RAI 4.1-6 (Use of Leak Before Break Methodology for ECWS Components)

Backqround:

UFSAR Appendix 9A provides the applicant's "Assessment of the Potential Effects of Through-Wall Cracks in the ECWS Piping." Specifically, UFSAR Appendix 9A states that the applicant identified through-wall cracks in the STP ECWS piping, which were initiated by pre-existing weld defects and propagated by a de-alloying growth phenomenon. UFSAR Appendix 9A states that potential effects of leakage in the ECWS were assessed for the following safety-related impacts at the plant:

1. Internal flooding in rooms containing these pipes and other rooms which receive drains from these sources.

2. Electrical shorts or grounds caused by water spray from the crack.

3. Reduction in ECWS flow through the heat exchangers served by the affected ECWS piping train.

4. Water losses from the essential cooling pump (ECP) not accounted for in the existing analysis.

5. Possible effects on the transient pressures when the pump is started or stopped.

UFSAR Appendix 9A also states that "STPEGS has analyzed the effects of the cracking and found that the degradation is slow so that rapid or catastrophic failure is not a consideration, and determined that the leakage can be detected before the flaw reaches a limiting size that would affect the operability of the ECWS." UFSAR Appendix 9A then references three flaw related analyses that were performed to support the applicant's basis that any potential leakage from the ECWS piping would be detected before a catastrophic fast fracture of the piping would occur:

1. HL&P Laboratory Report MT -3512A, "Evaluation of Cracked Elbow-to-Nozzle Weld from South Texas Project Unit 1 Essential Cooling Water System"

2. HL&P Laboratory Report MT-3512B, "Evaluation of Cracked Aluminum Bronze Pipe-to-Pipe Weld from South Texas Project Unit 2 Essential Cooling Water System"

3. Aptech Calculation No. AES-C-1630-2, "Calculation of Critical Bending Stress for Flawed Pipe Welds in the ECW System" Issue:

UFSAR Appendix 9A appears to be using a leak-before-break type of logic (leakage detection basis) to the assessment of potential flaws in the aluminum bronze ECWS components. The apparent cause basis in UFSAR Appendix 9A is predicated on the conclusion that the existing flaws that were detected in the aluminum bronze components were fabrication-induced flaws that propagated by an aluminum bronze de-alloying flaw growth mechanism.

Enclosure 1 NOC-AE-1 1002766 Page 13 of 15 The LRA does not mention the applicability and relationship of UFSAR Appendix 9A to the aging management basis for buried aluminum bronze ECWS piping components or evaluate whether the MT-3512A, MT-3512B, and AES-C-1630-2 technical evaluations that were referenced in that UFSAR Appendix 9A need to be identified as TLAAs for the LRA when compared to the six criteria for defining TLAAs in 10 CFR 54.3.

In addition, during the staff's audit of the STP LRA during the week of June 20 - 24, 2011, the staff also noted that the applicant's leak-before-break type of logic to the assessment of potential flaws in the aluminum bronze ECWS components appeared to be based on three additional assessments that were not referenced as being relevant in UFSAR Appendix 9A:

(1) a vendor-specific leakage seepage and soil diffusion calculation; (2) an applicant-specific leakage seepage and soil diffusion calculation that was used to verify the conclusions in the vendor-specific calculation; and (3) an applicant-specific engineering report that summarized the applicant's results in the vendor-specific and applicant-specific leakage seepage and soil diffusion calculations and that appears to have been the basis for the design basis conclusions in UFSAR Appendix 9A. However, UFSAR Appendix 9A does not list these documents as applicable references for its basis, and these evaluations did not include any flaw tolerance evaluations to support the applicant's claim that a leak in the ECWS aluminum bronze components would be detected prior to a catastrophic fast fracture in the system's aluminum bronze piping.

Thus, if the leakage detection basis in UFSAR Appendix 9A is to be relied upon for aging management, it would need to be supported by an appropriate time-dependent flaw tolerance evaluation to demonstrate: (1) that the critical flaw size for the applicable piping would not be less than the flaw size that would lead to a detectable leak at the soil or soil/gravel surface; or (2) if the critical crack size was greater than the flaw size that would lead to a detectable leak (i.e., the leak-detection size), that a flaw the size of the leak-detection size would not grow and reach the critical flaw size limit for the piping prior to the time that it would take the applicant to detect such a leak at the soil surface or soil/gravel surface in the vicinity of the affected piping. The staff also believes that any evaluations that were used to support this type of safety basis objective would be relevant even if the applicant had repaired the relevant indications under applicable ASME Code Section Xl repair criteria because the evaluations would still be needed to support the applicant's basis that visual examinations of the piping would be capable of detecting leakage from aluminum bronze ECWS components prior to a postulated fast fracture (i.e. catastrophic failure) of the piping.

In addition, the apparent cause basis in UFSAR Appendix 9A is predicated on the assumption that flaw growth was occurring by an aluminum bronze de-alloying mechanism. However, during its audit of the HL&P MT-3512A and MT-3512B lab reports, the staff noted that the lab reports also indicated the occurrence of some failure striations in the weld failure morphology photographs that could indicate that the flaw growth in the aluminum bronze materials had also been, at times, propagating by a low-cycle or high-cycle fatigue growth mechanism (as supported by the striations in weld failure photographs). Thus, the staff was concerned that the scope of the current design basis in UFSAR Appendix 9A might have been too limited in its assessment of the weld failures in the aluminum bronze components, and that the basis should also have accounted for the possibility of fatigue flaw growth as a potential failure mechanism.

Enclosure 1 NOC-AE-1 1002766 Page 14 of 15 Request:

Part 1 - Provide the basis on why the applicable vendor-specific and applicant-specific leakage, seepage, and soil diffusion analyses, and the applicable engineering report, that were used in support of the UFSAR Appendix 9A basis for the ECWS aluminum bronze components are not referenced as applicable reports in UFSAR Appendix 9A.

Part 2 - Clarify whether these vendor-specific and applicant-specific leakage seepage and soil diffusion analyses have been supported by any flaw tolerance analyses that would demonstrate that: (1) the critical flaw size for the applicable piping would not be less than the flaw size that would lead to a detectable leak (i.e., the leak-detection size) at the soil or soil/gravel surface, or (2) if the limiting critical flaw size was greater than the leak-detection size, that a flaw the size of the leak-detection size would not grow and reach the critical flaw size for the piping prior to the time that it would take the applicant to detect such a leak at the soil surface or soil/gravel surface.

Clarify whether such a flaw tolerance analysis (or analyses), if performed as part of the CLB or current design basis, will need to be identified as a TLAA(s) for the LRA in accordance with the criterion in 10 CFR 54.21(c)(1), as assessed against the six criteria for TLAAs in 10 CFR 54.3; or if they have not been included as part of the CLB, whether the CLB basis in UFSAR Appendix 9A will need to be updated to include a supporting flaw tolerance assessment in order to justify a pending license renewal approval decision by the Commission pursuant to the requirement criteria in 10 CFR 54.29.

Part 3 - Perform a comparison of the evaluations in HL&P Report Nos. MT-3512A and MT3512B, and in Aptech Calculation No. AES-C-1630-2, to the six criteria for defining analyses as TLAAs in 10 CFR 54.3, and to provide your bases on why any evaluations, analyses or calculations in these reports would not need to be identified as TLAAs under the requirements of 10 CFR 54.21 (c)(1).

Part 4 - Provide the basis on why scope of the apparent cause basis in UFSAR Appendix 9A does not need to consider, account for, and evaluate the possibility of fatigue flaw growth (i.e. flaw propagation by a fatigue-induced failure mechanism in addition to that which might be caused by a de-alloying mechanism) in these aluminum bronze components.

STPNOC Response:

Part 1 - The "applicant-specific" analysis is Calculation CC-5089, "Detection of seepage from ECW Pipes", which is currently referenced in the UFSAR on page 9A-2, in the 3 rd line of the 2 nd paragraph under section heading "Generic Issue - - Other Welds". The "vendor-specific" analysis is included as an attachment to Calculation CC-5089. Therefore, it is part of the calculation and is included in the reference mentioned above. The engineering report provides clarification of the calculation, in response to a specific question, but it does not alter the results of the calculation.

Part 2 - Section 9A of the UFSAR states, "Cracks large enough to approach the crack size for failure should be noticeable through soil changes which can be detected by walkdowns". There is a sound technical basis for this statement. The detection threshold was established in Calculation CC-5089 and the critical crack length was established in Aptech Calculation AES-C-1630-2 "Calculation of Critical Bending Stress for Flawed Pipe Welds in the ECW System" (reference 12 of UFSAR Section 9A). The crack length needed to produce a leak rate of 10 gallons per minute was established as less than the critical crack lengths in Aptech Calculation AES-C-1 964-7. This calculation is not specifically referenced in the UFSAR, but it provides documented technical basis

Enclosure 1 NOC-AE-1 1002766 Page 15 of 15 for the UFSAR sentence quoted above. STPNOC does not plan to revise Section 9A of the UFSAR, as it is deemed adequate as currently written to support current operation and also a period of extended operation.

The calculations referenced above do not predict a rate of aluminum-bronze de-alloying or rate of crack propagation. Lab examinations indicate that a pre-existing crack at the root of a weld will support de-alloying at the crack tip and the crack will propagate through the de-alloyed material until non-de-alloyed material is reached. This process can repeat until the crack extends through the wall of the material. The rate at which this crack propagation process occurs cannot be determined. Since there are no time dependent assumptions in these calculations, these are not TLAAs in accordance with 10 CFR 54.3(a) Criterion 3.

Part 3 - The HL&P aluminum-bronze material lab reports and the Aptech calculation of critical bending stresses do not predict a rate of aluminum-bronze de-alloying or rate of crack propagation. STP's experience with de-alloying of ECW System aluminum-bronze piping and components demonstrates that the process generally occurs over a long time period and there are a number of variables that affect whether the material will experience de-alloying and that affect the rate of de-alloying. Since there are no time dependent assumptions in these reports or the calculation, the report and calculation are not TLAAs in accordance with 10 CFR 54.3(a)

Criterion 3.

Part 4 - The ASME code does not require fatigue analysis of Class 3 piping. By 1992, de-alloying had been identified as a generic concern applicable to the aluminum-bronze material used in the ECW system. By May 1992, 90 of the approximately 800 fittings in the system had been observed to exhibit some form of through-wall leakage. The principal mechanism was determined to be de-alloying. The issue of de-alloying in the ECW system is considered a generic concern and is addressed formally in the UFSAR. Fatigue is a phenomenon that can occur in any piping system and is not unique to the ECW system. To date, STP has not identified cracking of de-alloyed aluminum-bronze with an indication that fatigue loading contributed to crack propagation. Laboratory tests indicate that crack propagation is a result of de-alloying at a pre-existing crack tip and propagation of the crack through a newly de-alloyed area at the crack tip with progressive crack tip de-alloying and propagation until the crack goes through-wall.

Therefore, fatigue is not discussed in Chapter 9A of the UFSAR.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 TABLE 1 ECW DE-ALLOYING DATA

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 1 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References 0 nt Te Metallurgical Exam Comments 1 7-6-87 Unit 1 (Ul) Essential Two pinhole leaks on NCR 87-77 Cast Chiller 11 C cast flange at butt weld.

Flange condenser Flange had cold spring outlet and weld fusion line indications.

2 12-11-88 Ul Cast Fracto-graphic features of the crack did not provide Essential LP showed 1/ inch long NCR 88-282, Flange definitive information concerning cracking Chiller 11C 6 indication on outside mechanism due to the corroded condition of the inch outlet diameter (OD) and 1.5 Southwest crack surface. Crack located adjacent to the weld valve inch on the inside Research heat affected zone (HAZ) and oriented parallel to diameter (ID). Crack Institute edge of the HAZ. Flange was sectioned (8 sections) located adjacent to a Metallurgical to determine extent of de-alloying. In leak section, a butt weld to 6 inch pipe Investigation of through-wall crack present at leak location and Leak in Aluminum through-wall de-alloying on both sides of the crack. Bronze Fitting In 5 sections, attack ranged up to 0.11 inch deep. In No.17-2520-520 the two sections opposite the leak, de-alloying was dated 1-6-89 and minimal.

Supplemental Supplemental Lab Report: Flange was sectioned (8 SRI Report 6 sections) to determine extent of de-alloying. Inall but 89 1 section, de-alloying at isolated spots along the bore with maximum depth 0.13 inch. At one location, continuous de-alloying along the bore and along face of the bore/face intersection with maximum depth of 0.16 inch. In 3 sections, isolated de-alloying along the flange face. In the other 5, continuous attack along the face for distances up to 0.7 inch from bore.

3 5-6-89 Unit 2 (U2) Self-cleaning Pinhole leak in 24-inch NCR 89-2-112, Weld Strainer 2C butt weld. Grinding EW-80837 bypass line revealed 3-inch long linear indication. No evidence of de-alloying by silver nitrate checks during defect excavation.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 2 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 4 1-30-89 Ul Crack was in the 316 SS and no de-alloying was 2 thermo- Cracking not SPR 890078 stainless found in the aluminum bronze socko-let fitting. wells in ECW associated with de- Failure Analysis steel (SS) Source of weepage were tiny fissures (liquation piping alloying of aluminum Report no. 8901-thermo- cracks) which can occur when copper alloys are bronze 03 EV Rev 1 EV wells welded to SS. Lab analysis indicated cracking Jan 89 welded to caused by liquid embrittlement of the SS and crevice aluminum corrosion. All SS thermo-wells were replaced in both bronze units with Aluminum Bronze thermo-wells or non-socko-let welded thermo-wells.

fittings (2) 5 1-30-89 U2 SS See above 1 thermo-well Cracking not See above thermo- in ECW associated with de-well piping alloying of aluminum welded to bronze alum bronze socko-let 6 5-20-90 U1 Cast Flange was sectioned in 8 pieces and examined. Essential 3.5 inch circumferential RFA 90-1219, Flange Maximum depth of de-alloying was 100 percent and Chiller 11 C 6 crack under the SPR 910099 average depth was 64.8 percent. De-alloying inch supply backing ring. Lab MT3047-2 occurred in the HAZ and in the base metal in the valve vicinity of the backing ring and not in the weld. Crack in flange is related to original installation where shop weld was cutout and re-welded.

A second flange from U2 was also examined (MT U2 Cast 3047-1) and leakage was attributed to a through-wall SPR 910099 Flange crack and not to de-alloying. Maximum depth of de- Lab MT 3047-1 alloying in the U2 Flange was 15.2 percent and (for U2) average was 8.3 percent. Crack in flange is related to original installation where shop weld was cutout and re-welded.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Paqe 3 of 17 TABLE 1 - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o ntType Metallurgical Exam Comments 7 10-30-90 U2 Cast Essential Through-wall leakage RFA 90-2108A Flange Chiller 21C at a crack in the weld condenser fusion line of a cast outlet weld neck flange.

8 3-28-91 U2 Cast Leakage due to through-wall de-alloying without Essential Through-wall leakage RFA 91-684 Lab Flange cracks. Flange cut into 10 sections to determine de- Chiller 21B 6 at 3 locations (4 1h thru MT-3383 alloying depth. Average depth of de-alloying was inch supply wall site found in the 0.226 inch with maximum thru wall (0.281 inch wall valve lab that was not yet thickness). leaking).

9 6-25-91 U2 Cast Rings cut out in two locations (one away from the Large Chiller Circumferential crack RFA 91-1005 Lab Flange weld) were sectioned into 8 pieces and examined to 22C 8 inch length at the ID was 2 MT-3727 determine crack and de-alloying extent. Average de- inlet supply inch and initiated at the alloying was 0.07 inch up to 0.19 inch at the location valve root of the weld. It away from the weld. Average de-alloying at the weld terminated in the weld root location was 0.10 inch. Average de-alloying at metal near the crown of the flange face (gasket crevice) was 0.07 inch. The the weld.

leak was the result of de-alloying at the tip of the crack.

10 7-13-91 U2 Weld See item 2 in weld table below for results of Lab MT- Component RFA 91-1096 3512B Cooling EW-151968 Lab Water (CCW) MT-3512B Heat Exchanger 2B Outlet Line 11 8-7-91 U1 Cast Diesel 3%-inch long hairline RFA 91-1246 Flange Generator crack in neck of cast (DG) 11 flange parallel to the Intercooler butt weld.

Expansion Bellows inlet

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 PaQe 4 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o ntType Metallurgical Exam Comments 12 01-92 U2 Cast Flange de-alloyed in area of the backing ring. No Essential RFA 92-0020 Flange crack found in this flange. Sectioned into 8 parts at Chiller 21 B RR-ENG-10 Lab two locations to determine de-alloying depths. De- 6-inch outlet MT 3840 alloying at the weld root location was insignificant and average de-alloying at the backing ring was 0.19 inch with maximum through-wall. De-alloying at the flange face was 0.26 inch at all the sections (flange thickness 1.41 inch).

13 01-92 U2 Cast Flange de-alloyed in areas of the weld root and at Essential Through-wall crack with RFA 92-0021 Flange the end of the backing ring. Through-wall crack Chiller 21 B 6 8 degrees at the OD RR-ENG-10 Lab found at the weld root. Sectioned into 8 parts at two inch inlet and 21 degrees at the MT 3840 locations to determine de-alloying and crack depths. ID Average de-alloying at the crack location was 0.09 inch (Wall 0.34 inch) and average de-alloying away from the crack was 0.05 inch with maximum 0.16 inch. De-alloying at the flange face was 0.03 inch at all the sections (flange thickness 1.41 inch).

14 02-92 U2 Cast The flange was de-alloyed at the weld root and at the Essential RFA 92-0216 Flange end of the backing ring. No cracking was found. Chiller 21C 6 RR-ENG-10 Lab Flange sectioned into 8 parts and at two transverse inch outlet MT 3923 planes to determine de-alloying depths. At the first location at the end of the backing ring the average de-alloying depth was 0.18 inch with a maximum depth through-wall (wall thickness 0.28 inch) at 2 locations. At the second location, the average de-alloying was 0.10 with a maximum depth through wall at 1 location through the root of the weld.

Average de-alloying at the flange face was 0.16 inch with maximum 0.23 inch (flange thickness 1.41inch).

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 5 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 15 3-23-92 U1 Leak result of de-alloying which initiated in repair Train 1B RFA 92-0359, 30x30x14 weld metal contained within the Tee. The area of supply line to SPR 92-742 RR-Extruded through-wall de-alloying initiation was confined to the Essential ENG-10 Tee (weld repair metal in the HAZ of the pipe-to-tee butt weld. Chiller Supplement 2 repair The repair weld metal was susceptible due to the 11B/12B Lab MT 4102 region in presence of a continuous second phase network that the Tee) may have contained gamma 2 phase. Review of fabrication documents shows cracking % inch long was found at the edge of the 14 inch tee outlet during the outlet extrusion process.

16 4-92 U2 Cast Flange leak was due to a crack extending from the DG 21 RFA 92-427, RR-Blind end of the backing ring to the weld root. At the end of Supply Line ENG-10 Lab MT Flange the backing ring the crack went through-wall. Flange End Flange 4046 was sectioned into 8 segments and the sectors on (6inch) either side of the leak were further sectioned into 5 equal parts to determine de-alloying and crack profile. Flange examined at 2 transverse planes with respect to pipe axis, location 1 at end of backing ring and location 2 the weld root. Average depth of de-alloying at location 1 was 0.045 inch with maximum depth through-wall (wall thickness 0.28 inch). At location 2, the average depth was 0.37 inch with maximum depth of 0.25 inch (wall thickness 0.37 inch).

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 6 of 17 TABLE I - ECW DE-ALLOYING DATA N Date J Compone Metallurgical Exam Information Location Information without References 0 nt Type I I Metallurgical Exam I Comments 17 110-01-92 U1 Cast Both flanges were sectioned into 8 segments to Essential Preemptive removal of EW-160727, Flanges determine de-alloying profile. Extent of de-alloying Chiller 12B cast flanges (neither EW-160729, was determined at 3 locations on all 8 segments: at Inlet Flange flange had any surface Lab MT-4089 the backing ring, weld root, and flange face. and Outlet indications)

Average depth of de-alloying for the first flange was Flange 0.05", 0.08", and 0.04" for the backing ring, weld root, and flange face, respectively. The greatest amount of de-alloying was 0.22 inch at the 2250 position at the weld root.

Average depth of de-alloying for the second flange was 0.03", 0.03", and 0.02" for the backing ring, weld root, and flange face, respectively. The greatest amount of de-alloying was 0.07 inch at the 900 Dosition at the end of the backing ring

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 7 of 17 TABLE I - ECW DE-ALLOYING DATA N Date [ Compone Metallurgical Exam Information Location Information without References o nt Type I I Metallurgical Exam Comments 18 10-22-92 U1 Cast Each flange was sectioned into 8 segments to Essential Preemptive removal of EW-1 60728, Flanges determine de-alloying profile. Extent of de-alloying Chiller 11 B cast flanges (none of EW-1 60730, was determined at 3 locations on all 8 segments: at Inlet Valve the flanges had any EW-1 60732, the backing ring, weld root, and flange face. Upstream surface indications) EW-160733 Average depth of de-alloying for the first flange was Flange, Lab MT-4141 0.10", 0.18", and 0.17" for the backing ring, weld Essential root, and flange face, respectively. The greatest Chiller 11A amount of de-alloying was 0.33 inch at the 00 Inlet and position on the flange face. Outlet Average depth of de-alloying for the second flange Flanges and was 0.01", 0", and 0.01" for the backing ring, weld Inlet Valve root, and flange face, respectively. The greatest Downstream amount of de-alloying was 0.03 inch at the 900 and Flange 1800 positions at the end of the backing ring.

Average depth of de-alloying for the third flange was 0.02", 0.04", and 0.07" for the backing ring, weld root, and flange face, respectively. The greatest amount of de-alloying was 0.14 inch at the 1350 position on the flange face.

Average depth of de-alloying for the fourth flange was 0.02", 0.005", and 0.04" for the backing ring, weld root, and flange face, respectively. The greatest amount of de-alloying was 0.06 inch at the 3150 Dosition on the flanae face.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Paae 8 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 19 12-18-92 U1 Defect originated in a weld repair in the Tee casting DG13 Weld Repaired 10x10x6 and crack propagated into the butt weld. A 1 inch Intercooler Service Request Cast Tee diameter plug sample was removed from the cracked 10 inch 161574 butt weld and sent to lab for analysis. Lab confirmed Return Tee Lab MT-4303 and the crack originated in the tee adjacent to the weld SPR 92-1575 prior to service. Crack promoted de-alloying in the cast tee by progressive extension of the crack through de-alloyed material. The maximum depth of de-alloying from the inside diameter surface was 0.1 inch in the plug specimen. The crack did not extend through-wall. This area was ground out and weld repaired during fabrication of the tee. Note this Tee was subsequently replaced after another through-wall indication developed in the bulk portion of the Tee (see Table item 44) 20 2-1-93 U2 Cast De-alloyed flange weld with pre-existing cracks DG21 Lab MT 4907 12-Flange subjected to Bend Test to Failure. On the fracture Intercooler 10-93 surface, 2 preexisting cracks (one through-wall) were Supply noted. The de-alloying and crack profiles were mapped. Inthe area of the through-wall crack, de-alloying depth ranged from 50 to 100percent. Inthe area of the partial through-wall crack, de-alloying depth ranged from 35 percent to 94 percent.

Mapping results provided in the lab report.

21 3-17-93 Valve Both sides of the valve were sectioned into 2-EW-0287, Leak at the inlet end of MT-4629 Original approximately 45 degree sectors. The leak was the Supplementa a A-inch ball valve with Equipment result of localized de-alloying in the socket weld ICooler a vendor supplied Manufactur between the valve body and the adapter. Through- return root socket welded adapter.

er (OEM) wall dealloying was confined to the leak location valve Socket where a two phase microstructure extended from the Weld socket crevice through the weld.

22 12-6-93 U2 Weld See item 9 in Table 2 for MT 5487 results of Lab 6 inch Elbow- PCF 212839A, testing. Chiller 21 C Lab MT 5487 I _shop weld

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 9 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 23 12-8-93 U2 Cast De-alloying observed at small area on the OD DG 22 Crack initiated .09 inch Lab MT 5369, No Flange surface of the weld as a result of a through-wall Supply Line from the weld root. relief.

crack. Crack appears to have initiated prior to End Flange Extend service. Outside the HAZ, the base metal was de- (6-inch) circumferentially was 9 alloyed to a depth of approx 0.01 inch along the degrees on OD and 60 crack faces on either side of the crack and along the degrees on ID crevice between Flange and Backing Ring. In the HAZ de-alloying of crack faces was most severe just before the crack penetrated into the weld. De-alloying to greater than 0.05 inch was found in one location approx 180 degrees removed from the crack location. No de-alloying at the flange face.

24 3-30-94 Valve OEM Leaks on the inlet end of both valves resulted from 2-EW-0373B, Multiple residue Lab MT-5368 Socket de-alloying of the weld metal in the socket weld Screen Wash deposits on a vendor Weld made in the shop between the valve body and 2B Flow socket weld between adaptor. Through-wall de-alloying confined to HAZ Indicator root the valve body and a where the morphology of the second phase was valve  %-inch adaptor.

changed when the pipe to adaptor field weld was made. Aluminum bronze has a susceptible microstructure when a continuous second phase network exists. On both valves, no de-alloying in the field welds between the adaptor and pipe.

25 3-30-94 Valve OEM See above (item 24) 2-EW-0374B, Multiple residue Lab MT-5368 Socket Screen Wash deposits on a vendor Weld 2B Flow socket weld between Indicator root the valve body and a valve  %-inch adaptor.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Pae 10 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o ntType Metallurgical Exam Comments 26 7-26-95 Ul Cast Half coupling Residue buildup in a Condition Report Fitting with for vent stub cast fitting at the socket (CR) CR 95-Socket in DG13 weld to the vent pipe 9332, CR 97-Weld Lube Oil stub. 16442, CR 97-Cooler 17172, CR 97-supply line 17425 This small bore socket welded cast fitting was missed in the original small bore replacement program probably since it was only shown on a Large Bore isometric drawing.

27 9-18-95 U1 Socket The material sent for lab analysis contained only a Half coupling Leak at crack in drain CR 95-10872, Welded small portion of the weld material. Since the leak was to 1 inch pipe nipple of a Lab MT-6027 Pipe Nipple likely located in the weld material, the mechanism drain pipe cantilevered valve.

causing the leak could not be established. No stub in evidence of de-alloying seen in the sample provided Mechanical to the lab. Auxiliary Building return header 28 4-23-96 U2 Cast Chiller 22A 1%-inch long crack in CR 96-4612, RR-Flange 8-inch return neck of cast flange ENG-14 flange parallel to butt weld.

downstream Radiographic of 2-EW- inspection indicated 3 1002 and 1/16-inch subsurface crack length.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 11 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 29 4-24-96 U1 Cast Crack that caused the leak was result of inter- Chiller 12A 1%-inch long crack in CR 96-4652, RR-Flange granular de-alloying at the edge of the HAZ of the 8-inch return neck of cast flange ENG-14 weld attaching pipe to flange. Three sections A, B & flange parallel to butt weld. TR-1 1078 C were taken through the pipe and the extent of de- downstream Radiographic alloying was determined on the face of each section. of 1-EW- inspection indicated 4 The average depth of de-alloying in section A was 1002 and 1/16-inch 14.5 percent, B was 31 percent and C (away from subsurface crack the crack) was very small. length.

30 5-22-96 U2 6x6x6 Self cleaning Two residue spots on a CR 96-5918, RR-Cast Tee strainer 2B cast Tee at a butt weld ENG-14 backwash to a cast flange.

31 2-03-97 U2 Tee sectioned into 37 sections with etching of each DG 23 Jacket Residue buildup at one CR 97-1775, RR-1Ox1Ox6 section to show de-alloyed area. Plots made at 3 Water Cooler spot within the bulk of ENG-17, CREE Cast Tee locations showing de-alloying depth versus axial and Supply line the 10-inch portion of 05-1919-4 circumferential locations. De-alloying depths varied the cast Tee.

significantly over the surface area of the tee from zero to 100 percent through-wall.

32 10-6-97 U2 Essential Residue buildup at CR 98-3106, RR-1Ox1Ox6 Chiller 2A several pinpoints on a ENG-19, CR 97-Cast Tee supply line cast Tee near the 10- 16160, (originally cross inch inlet butt weld. classified as connect Tee blemish) 33 10-7-97 U2 Cast ECW Pump Moisture buildup on CR 97-16264, Flange 2C discharge cast flange neck near RR-ENG-18, 3 inch vent the butt weld.

line 2-FO-6956 upstream flange 34 7-1-98 U2 Cast Screen Wash Residue buildup on the CR 98-10849, Pump Booster flange directly below RR-ENG-27 Pump 2C 3- the drilled connection inch outlet for the pump flange mechanical seal flush tubing connection.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Paae 12 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o _ nt Type Metallurgical Exam Comments 35 11-22-99 U2 Cast Chiller 2C to Residue buildup in CR 99-16610, Flange 2B 10-inch several spots on the RR-ENG-35 cross tie neck of cast flange isolation near the butt weld. Two valve 2-EW- areas of residue buildup 0275 cross- had spots forming along a tie side line on the flange neck flange near and parallel to the butt weld.

36 7-18-00 U2 Cast 2-EW-0277 Drop of water next to the CR 00-11814, no Valve Self- gasket and multiple relief request Cleaning pinpoint residue buildup Strainer 2A spots on the valve body.

Emergency Leakage could be a combination of gasket Backwash seepage and valve body Valve de-alloying.

6-inch cast valve 37 7-24-00 U1 Train 1A Residue buildup at a spot CR 00-12050, 30x30x14 supply line to on the bottom of 14-inch RR-ENG-2-24, Extruded Essential portion of 30-inch by 30- Similar to de-Tee (Weld Chiller inch by 14-inch extruded alloyed condition repair 11A/12A Tee in Train 1B region in extruded tee the Tee) (Item 15) where weld repair was performed during fabrication of the tee. Lab report MT 4102 investigated the region in the Train 1B Tee.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Paae 13 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 38 1-17-01 U1 Cast Screen Wash Residue buildup at several CR 01-912, RR-Flange Booster spots forming along a line ENG-225, Pump 1B on the flange neck near flow element the butt weld. Line of 1-FE-6958 spots is parallel to the butt weld and about 1/22-inch upstream long..

flange 39 1-17-01 U1 Valve 1-EW-0093, Seepage at two locations CR 01-914 Cast Seat Essential at the joint between the Essential Chiller Retainer Chiller 11 C cast seat retainer and the 11C was 6-inch Inlet cast valve body. Seepage abandoned and Valve could gasketbeseal duecombined to poor with this tivavevalve was was possible de-alloying in the removed from the seat retainer, system.

40 2-1-01 U2 Cast 2-EW-PSV- Residue buildup spot on CR 01-1888 Valve 6865, DG 22 the cast bonnet near the The bonnet is not Bonnet Relief Valve outlet flange. pressurized but 1-inch retains the spring on this PSV and directs flow to the floor drain when the PSV lifts.

41 11-26-01 U1 Cast Screen Wash Residue buildup at several RR-ENG-2-26, Flange Pump 1C 3 spots on the flange neck CR 01-19152 inch suction near the butt weld.

flow orifice Flange 1-EW-FE-6959 42 11-28-01 Valve OEM 2-EW-0284 Residue buildup at a spot CR 01-19319 Socket Supplementa on the vendor valve to Similar to de-Weld I Cooler 2A 1/2-inch adapter socket alloyed condition transmitter/flo weld in OEM adapter w indicator, socket welds FT/Fl 6856 (Items 21, 24, low side root and 25). Lab valve report MT 5368

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Paqe 14 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 43 11-04-02 U2 Cast Pump 2B 3- Water drop forms on top CR 02-16257 no Flange inch of cast flange at one spot relief request -

discharge near the flange neck butt found and fixed in vent line weld. the outage check valve 2-EW-0370B upstream flange 44 11-6-02 U1 Cast DG13  %-inch residue deposit in CR 02-16395 10xl0x6 Intercooler about a 11/2-inch round This Tee was Tee 10-inch circle of secondary originally repaired Return Tee located nearrun the 10-inch theofmiddle of by plug welding ir the cast 1992 (See item Tee. 19 of this Table).

This tee was replaced when the second through-wall leak was found in 2002.

45 10-15-03 U2 Cast Essential Residue buildup at several CR 03-15710 Flange Chiller 12B spots along a line on the 8-inch ECW flange neck near the butt Return Valve weld. Line of spots is 1-EW-1004 parallel to the butt weld downstream and about %-inch long flange 46 10-15-03 U2 Cast Self-cleaning 11/2-inch long area of CR 03-15730 Flange Strainer 2B pinpoint residue buildup Emergency parallel to butt weld in Backwash neck of cast flange)

Valve 2-EW-0278 Inlet Flange

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 15 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 47 7-27-05 Ul Cast 6 inch return Residue buildup at several CR 05-9622 Blind line flange spots forming along a line Although the 150-Flange from on the flange neck near ton Essential abandoned the butt weld. Line of Chillers have been 150Ton is parallel spotsand to the butt abandoned, this weld about 1/2-inch flange is Chiller 11B long. downstream of the blind and is pressurized by ECW Train lB.

48 1-9-06 U1 Cast 10-inch Through-wall indications CR 06-360 Flange cross-tie are several small spots valve with residue buildup at the upstream of flange neck near the butt Essential weld.

Chillers 11C/12C to 11AI12A 1-EW-0276 Upstream Flange 49 1-16-06 U2 Cast 2-EW-PSV- Residue buildup spot on CR 06-696 The Valve 6866, the cast bonnet. bonnet is not Bonnet Supplementa pressurized but I Cooler 2B retains the spring 1-inch on this PSV and thermal directs flow to the valve relief floor PSV drain lifts. when the 50 7-6-06 U2 Cast 10-inch DG Residue buildup at one CR 06-8594 10x10x4 21 supply spot on the cast Tee at Tee header and 4 the inlet butt weld fusion inch Lube Oil line.

Cooler supply Tee

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Paae 16 of 17 TABLE I - ECW DE-ALLOYING DATA _

N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 51 6-6-07 U2 Cast 2-EW-0204, Residue buildup on the CR 07-9166 Valve Seat DG 23 valve seat retainer near Retainer Engine the flange gasket. Could Cooler be a combination of Return Flow gasket leakage and Balance dealloying.

Throttle Valve 52 12-2-08 U2 Cast Essential Residue buildup about CR 08-18477 Flange Chiller 22B one half inch long in a line ECW return parallel to the butt weld for throttle valve the downstream flange.

2-EW-1 004 flange 53 8-19-10 U1 Cast Piping flange Linear through-wall CR 10-17899 This Flange downstream indication with residue portion of piping of buildup. The indication is has been isolated abandoned in the neck of the cast from ECW but is 150Ton flange, about 1/4 inch still part of the pipe Essential away and roughly parallel support structure Chiller 11 A to the flange to pipe shop for the 300-ton weld. Essential Chiller 12A ECW piping.

54 8-19-10 U1 Cast 1-EW-PSV- Residue buildup spot on CR 10-17957 The Valve 6855, DG 11, the cast bonnet near the bonnet is not Bonnet 1-inch outlet flange. pressurized but thermal relief retains the spring valve on this PSV and directs flow to the floor drain when the PSV lifts.

Attachment 1 to Enclosure 1 NOC-AE-1 1002766 Page 17 of 17 TABLE I - ECW DE-ALLOYING DATA N Date Compone Metallurgical Exam Information Location Information without References o nt Type Metallurgical Exam Comments 55 7-28-11 U2 Cast 1-EW-FV Residue buildup at CR 11-12309 Valve Body 6936 several discrete spots on ECW 2B the valve body at the Return Header machined inlet portion Blowdown near the flange.

Valve

Attachment 2 to Enclosure 1 NOC-AE-1 1002766 TABLE 2 ECW WELD CRACK DATA

Attachment 2 to Enclosure 1 NOC-AE-1 1002766 Page 1 of 3 TABLE 2 - ECW WELD CRACK DATA No Date Weld Metallurgical Exam Information Information Reference/ Comments Location without Metallurgical Exam 1 5-6-89 U2 Train 2C Pinhole leak in NCR 89-2-112, EW-80837 24 inch ECW 24-inch butt weld.

Strainer Grinding Bypass Line revealed 3-inch (with backing long linear ring) indication. No evidence of de-alloying by silver nitrate checks during defect excavation.

2 7-13-91 U2 Train 2B 30 In-service 5-% inch crack initiated at tip of pre- Crack location Lab MT-3512B (Repaired inch CCW existing lack of fusion defect and propagated by had been subject Failure Analyzed)

Heat combination of progressive, local de-alloying and to major repair Exchanger line crack growth through de-alloyed material. Other during (with backing areas showed only slight de-alloying with no crack construction with ring) propagation. a weld width double a normal weld.

3 8-6-91 U1 Train 1B 30 In-service 4 inch crack initiated at tip of pre-existing Weld was cut out RFA 91-1241, RR-ENG-10, inch line cracks and/or lack of fusion defect and propagated and re-welded SPR-910273, Lab MT-between elbow by combination of progressive, local de-alloying and during original 3512A (Repair cracked and and CCW Heat crack growth through de-alloyed material. Crack installation repair failure analyzed)

Exchanger propagation was confined to the deepest portion of (with backing the pre-existing defect. Other areas showed only ring) slight de-alloying with no crack propagation.

4 12-13-91 U1 re-crack of Lab analysis showed part of a crack occurred during RFA 91-2056, EW-1 54081, weld above welding and the balance progressed by the Lab MT-3800

Attachment 2 to Enclosure 1 NOC-AE-1 1002766 Paae 2 of 3 TABLE 2 - ECW WELD CRACK DATA No Date Weld Metallurgical Exam Information Information Reference/ Comments Location without Metallurgical Exam mechanism of de-alloying and cracking that is identified in earlier failure analyses 5 11-5-91 U1 Weld Train Crack occurred subsequent to an earlier weld repair. Crack on OD 5.3 RFA 91-1803, RR-NNG-10, 1C 30 inch No de-alloying noted on the ID and only minimal de- inch and ID 13.6 Lab MT-5623 Line ECW alloying observed along the fracture surface. inch.

Intake Average through-wall crack widths of 0.029 inch Structure (with (20.4 degrees) and 0.049 inch (31 degrees).

backing ring) 6 6-11-93 Same weld as Re-crack at EW-1 79340 above repair location 7 11-7-91 U1 Train 1A 30 Microscopy of the microstructure from a boat sample Seepage from a RFA 91-1835, EW-103016, inch Supply showed de-alloying in the vicinity of a crack was fine hair line RR-ENG-10, Lab MT-4181 Line in mechanism responsible for the leak. De-alloying was crack about 11/4-Mechanical predominately located around the cracked region inch long on the Auxiliary and not in area away from the crack. surface and Building about 3%-ich (with backing long on the pipe ring) internal diameter.

8 12-6-93 U2 Essential Presence of pre-existing welding cracks at the Moisture and EW-212839, Lab MT-5487 Chiller 11C 6 juncture between the piping and backing ring. Crack residue on a inch Elbow dimensions were obtained by examining cross shop weld with a (vendor weld sections at various locations around the pipe. backing ring with backing Section of material containing a portion of the between a ring) through-wall crack was broken open to view the wrought elbow fracture surface. Crack is semi-elliptical with a length and pipe.

approximately twice the maximum radial crack depth at the failure location.

9 1-4-94 U2 DG 23 Preexisting 10 inch weld crack allowed de-alloying to Moisture and EW-212847, Lab MT-5050 supply line 10- initiate in the susceptible weld metal microstructure residue buildup inch weld at and progress through-wall. 8 segments removed at weld between cast 1Ox1Ox6 from ring in two locations (second location away pipe and cast Intercooler from the weld). Sections were ground and etched to Tee.

supply Tee reveal crack and de-alloying extent. At the crack I (with backing location, crack depth up to 0.31 inch (wall 0.44 inch)

Attachment 2 to Enclosure 1 NOC-AE-1 1002766 Page 3 of 3 TABLE 2 - ECW WELD CRACK DATA No Date Weld Metallurgical Exam Information Information Reference/ Comments Location without Metallurgical Exam ring) with de-alloying at average 14 percent. In the section location away from the crack, de-alloying averaged 10 percent.

10 1-11-94 U2 DG 23 No evidence of a leak through-wall was found in the A possible EW-212847, Lab MT-5050 Intercooler 6- pipe to elbow weld. 8 segments removed from ring in second indication inch supply two locations (second location away from the weld). was discovered line weld Sections were ground and etched to reveal crack at a shop weld between pipe and de-alloying extent. Crack depth up to 0.07 inch between a and elbow with a de-alloyed depth up to 0.08 inch (wall downstream (with backing thickness 0.34 to .41 inch) at the same section. elbow and 6-inch rin_ pipe,

Enclosure 2 NOC-AE-1 1002766 Enclosure 2 STP LRA Changes with Line-in/Line-out Annotations

Enclosure 2 NOC-AE-1 1002766 Page 1 of 6 AI.37 SELECTIVE LEACHING OF ALUMINUM BRONZE The Selective Leaching of Aluminum Bronze program manages loss of material due to selective leaching of aluminum bronze (copper alloy with greater than eight percent aluminum) components exposed to raw water within the scope of license renewal. The Selective Leaching of Aluminum Bronze program is an existing program that is implemented by STP procedure.

The procedure directs that every six months (not to exceed nine months), an inspection of all aluminum bronze components be completed. STP has buried piping with less than eight percent aluminum content, and that is not susceptible to dealloying. However, there are welds in which the filler metal is a copper alloy with greater than eight percent aluminum material.

Therefore, the procedure directs that a yard walkdown be performed above the buried piping with aluminum bronze welds, from the intake structure to the unit and from the unit to the discharge structure to look for changes in ground conditions that would indicate leakage.

Aluminum bronze (copper alloy with greater than 8 percent aluminum) components which are found to have indications of through-wall de-alloying are evaluated, and scheduled for replacement by the corrective action program. Components with indications of through-wall de-alloying, associated with piping greater than one inch in diameter, will be replaced by the end of the next refueling outage. Destructive examinations of a sample of through-wall de-alloyed components will be performed to determine the extent of de-alloying before and after the period of extended operation.

Enclosure 2 NOC-AE-1 1002766 Page 2 of 6 B2.1.37 Selective Leaching of Aluminum Bronze Program Description The Selective Leaching of Aluminum Bronze program manages loss of material due to selective leaching for aluminum bronze (copper alloy with greater than eight percent aluminum) components exposed to raw water within the scope of license renewal. This plant-specific program will use requirements of the Selective Leaching of Materials program (B2.1.17) specifically relating to aluminum bronze components. The selective leaching of aluminum bronze is applied in addition to the Open-Cycle Cooling Water program (B2.1.9).

The Selective Leaching of Aluminum Bronze program is an existing program that is implemented by plant procedure. This procedure directs that every six months (not to exceed nine months), an inspection of aluminum bronze (copper alloy with greater than eight percent aluminum) components be completed. STP has buried copper piping with less than eight percent aluminum content that is not susceptible to de-alloying. However, there are welds in which the filler metal is copper alloy with greater than eight percent aluminum material.

Therefore, the procedure directs that a yard walkdown be performed above the buried piping with aluminum bronze welds, from the intake structure to the unit and from the unit to the discharge structure to look for changes in ground conditions that indicate leakage. Aluminum bronze (copper alloy with greater than 8 percent aluminum) components which are found to have indications of through-wall de-alloying are evaluated, and scheduled for replacement by the corrective action program. Components with indications of through-wall de-alloying, greater than one inch, will be replaced by the end of the next refueling outage.

Aging Management Program Elements The results of an evaluation of each element against the 10 elements described in Appendix A of NUREG-1800, Standard Review Plan for Review of License Renewal Applications for NuclearPower Plants are provided below.

Scope of Program (Element 1)

The Selective Leaching of Aluminum Bronze program manages loss of material due to selective leaching for aluminum bronze (copper alloy with greater than eight percent aluminum) pumps, piping welds and valve bodies exposed to raw water within the scope of license renewal. These aluminum bronze (copper alloy with greater than eight percent aluminum) components with raw water internal environments are susceptible to loss of material due to selective leaching (de-alloying).

STP has analyzed the effects of de-alloying and found that the degradation is slow so that rapid or catastrophic failure is not a consideration. STP has determined that the leakage can be detected before the flaw reaches a limiting size that would affect the intended functions of the essential cooling water and essential cooling water screen wash system. The prudent course of action is to continue monitoring and replace components when needed. Destructive examinations of through-wall de-alloyed components will be performed to determine the extent of de-alloving. If components are identified as leaking during the ten year period prior to the period of extended operation, then a destructive metallurgical examination of one leakinq component per unit will be performed. Preference in the selection of the component to be

Enclosure 2 NOC-AE-1 1002766 Page 3 of 6 destructively examined will be given to a leakinq weld with a backing ringq that would be similar to the welds in buried ECW wrought aluminum bronze piping.

This procedure directs that every six months (not to exceed nine months), an inspection of all susceptible aluminum bronze (copper alloy with greater than eight percent aluminum) components be completed and any components that show evidence of de-alloying will be replaced by the end of the next refueling outage. If no leaking components are identified as leaking during the ten year period prior to the period of extended operation, destructive examination will be performed on the current inventory of leaking components that were removed from service prior to this period. STP has buried copper alloy piping with less than eight percent aluminum that is not susceptible to de-alloying. However, there are welds in which the filler metal is copper alloy with greater than eight percent aluminum material.

Therefore, the procedure directs that a yard walkdown be performed above the buried piping aluminum bronze welds, from the intake structure to the unit and from the unit to the discharge structure to look for changes in ground conditions that indicate leakage. Aluminum bronze (copper alloy with greater than 8 percent aluminum) components which are found to have indications of through-wall de-alloying are evaluated, and scheduled for replacement by the corrective action program. If leakinq below-grade welds are discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination.

Components, greater than one inch, will be replaced by the end of the next refueling outage.

If components leak during the period of extended operation, up to an additional four leaking components (i.e. two per unit) will be destructively examined during the period of extended operation, ifthrough-wall leaks are observed.

Preventive Actions (Element 2)

The Selective Leaching of Aluminum Bronze program does not prevent degradation due to aging effects but provides for inspections to detect aging degradation prior to the loss of intended functions.

The Open-Cycle Cooling Water program (B2.1.9) uses an oxidizing biocide treatment (sodium hypochlorite and sodium bromide) to reduce the potential for microbiologically influenced corrosion.

ParametersMonitored or Inspected (Element 3)

The Selective Leaching of Aluminum Bronze program includes visual inspections every six months (not to exceed nine months) for de-alloying in all susceptible aluminum bronze (copper alloy with greater than eight percent aluminum) components. During these inspections, if evidence of through-wall de-alloying is discovered, the components are evaluated and scheduled for replacement by the corrective action program. Components, greater than one inch, will be replaced by the end of the next refueling outage.

During the walkdown of the buried essential cooling water piping, the ground is observed for conditions that would indicate leakage due to selective leaching. Whenever aluminum bronze materials are exposed during inspection of the buried essential cooling water piping, the components are examined for indications of selective leaching. If leaking below-grade welds are

Enclosure 2 NOC-AE-1 1002766 Page 4 of 6 discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallur-gical examination.

Detection of Aging Effects (Element 4)

The Selective Leaching of Aluminum Bronze program includes visual inspection of aluminum bronze (copper alloy with greater than eight percent aluminum) components to determine if selective leaching of these components is occurring. Every 6 months, walkdown is performed above the buried essential cooling water piping containing copper alloy welds with an Aluminum content greater than 8 percent. During the walkdown, the soil is observed to identify conditions that may be an indication of leakage due to selective leaching. Whenever aluminum bronze materials are exposed during inspection of the buried essential cooling water and ECW screen wash system piping, the components are examined for indications of selective leaching. If leaking below-.grade welds are discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination.

Aluminum bronze (copper alloy with greater than 8 percent aluminum) components which are found to have indications of through-wall de-alloying are evaluated, and scheduled for replacement by the corrective action program. Components, greater than one inch, will be replaced by the end of the next refueling outage. If components are identified as leaking during the ten year period prior to the period of extended operation, then a destructive metallurgical examination of one leaking component per unit will be performed. Preference in the selection of the component to be destructively examined will be given to a leaking weld with a backing ring that would be similar to the welds in buried ECW wrought aluminum bronze piping. If components leak during the period of extended operation, up to an additional four leaking components (i.e. two per unit) will be destructively examined during the period of extended operation, if through-wall leaks are observed. If no leaking components are identified as leaking during the ten year period prior to the period of extended operation, destructive examination will be performed on the current inventory of leaking components that were removed from service prior to this period.

Monitoring and Trending (Element 5)

There is no monitoring and trending for the visual inspections of aluminum bronze components.

Acceptance Criteria(Element 6)

De-alloying of aluminum bronze components is a well known phenomenon at STP. A long term improvement plan was developed in May 1992. As a result of these analyses, aluminum bronze (copper alloys with greater than eight percent aluminum) components are visually inspected every six months (not to exceed nine months). Upon discovery of visual evidence of through-wall de-alloying, components are evaluated, and scheduled for replacement by the corrective action program. Components, greater than one inch, will be replaced by the end of the next refueling outage. Due to the slow nature of de-alloying, this replacement interval provides reasonable assurance that the systems and components within the scope of this program will continue to perform their intended functions consistent with the current licensing basis for the period of extended operation.

Enclosure 2 NOC-AE-1 1002766 Page 5 of 6 CorrectiveActions (Element 7)

STP site QA procedures, review and approval process, and administrative controls are implemented in accordance with the requirements of 10 CFR 50 Appendix B and are acceptable in addressing corrective actions. The QA program includes elements of corrective action, and is applicable to the safety-related and nonsafety-related systems, structures and components that are subject to aging management review.

Confirmation Process(Element 8)

STP site QA procedures, review and approval process, and administrative controls are implemented in accordance with the requirements of 10 CFR 50 Appendix B and are acceptable in addressing confirmation processes and administrative controls. The QA program includes elements of corrective action, and is applicable to the safety-related and nonsafety-related systems, structures and components that are subject to aging management review.

Administrative Controls (Element 9)

See Element 8.

OperatingExperience (Element 10)

A review of the STP plant-specific operating experience indicates that macrofouling, general corrosion, erosion-corrosion, and through-wall de-alloying have been observed in aluminum bronze components. STP has analyzed the effects of the through-wall de-alloying and found that the degradation is slow so that rapid or catastrophic failure is not a consideration. STP has determined that the leakage can be detected before the flaw reaches a limiting size that would affect the intended functions of the essential cooling water and essential cooling water screen wash system. A long range improvement plan and engineering evaluation were developed to deal with the de-alloying of aluminum bronze components when de-alloying has been identified.

Based on these analyses, the approach has been to evaluate components, and schedule replacement by the corrective action program. Components with indications of through wall de-alloying, associated with piping greater than one inch in diameter, will be replaced by the end of the next refueling outage. A monitoring and inspection program provides confidence in the ability to detect the leakage.

Enhancements None Prior to the period of extended operation, the following enhancements will be implemented in the following program elements:

Scope of Program (Element 1)

Procedures will be enhanced to perform destructive examinations of through-wall de-alloyed components to determine the extent of de-alloving. If components are identified as leaking during the ten year period prior to the period of extended operation, then a destructive metallurgical examination of one leaking component per unit will be performed. Preference in the selection of the component to be destructively examined will be given to a leaking weld with a backing ring that would be similar to the welds in buried ECW wrought aluminum bronze piping. If no leaking components are identified as leaking during the ten year period prior to the

Enclosure 2 NOC-AE-1 1002766 Page 6 of 6 period of extended operation, destructive examination will be performed on the current inventory of leaking components that were removed from service prior to this period. If leaking below-grade welds are discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination. If components leak during the period of extended operation, up to an additional four leaking components (i.e. two per unit) will be destructively examined during the period of extended operation, if through-wall leaks are observed.

Parameters Monitored and Inspected (Element 3)

Procedures will be enhanced to indicate that whenever aluminum bronze materials are exposed during inspection of the buried essential cooling water piping, the components are examined for indications of selective leaching. If leaking below-grade welds are discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination.

Detection of Aging Effects (Element 4)

Procedures will be enhanced to indicate that whenever aluminum bronze materials are exposed during inspection of the buried essential cooling water piping, the components are examined for indications of selective leaching. If leaking below-grade welds are discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination. If components are identified as leaking during the ten year period prior to the period of extended operation, then a destructive metallurgical examination of one leaking component per unit will be performed. Preference in the selection of the component to be destructively examined will be given to a leaking weld with a backing ring that would be similar to the welds in buried ECW wrought aluminum bronze piping. If components leak during the period of extended operation, up to an additional four leaking components (i.e. two per unit) will be destructively examined during the period of extended operation, if through-wall leaks are observed. If no leaking components are identified as leaking during the ten year period prior to the period of extended operation, destructive examination will be performed on the current inventory of leaking components that were removed from service prior to this period.

Conclusion The continued implementation of the Selective Leaching of Aluminum Bronze program provides reasonable assurance that aging effects will be managed such that the systems and components within the scope of this program will continue to perform their intended functions consistent with the current licensing basis for the period of extended operation.

Enclosure 3 NOC-AE-1 1002766 Enclosure 3 New Regulatory Commitment

Enclosure 3 NOC-AE-1 1002766 Page 1 of 1 A4 License Renewal Commitments Table A4-1 identifies proposed actions committed to by STPNOC for STP Units 1 and 2 in its License Renewal Application. These and other actions are proposed regulatory commitments. This list will be revised, as necessary, in subsequent amendments to reflect changes resulting from NRC questions and STPNOC responses. STPNOC will utilize the STP commitment tracking system to track regulatory commitments. The Condition Report (CR) number in the Implementation Schedule column of the table is for STPNOC tracking purposes and is not part of the amended LRA.

T~hl", 614_-4 I i,'- nQoQ PIfIA113I (r1-m ,'ifM.Mnf Item # Commitment LRA Implementation:

Section Schedule 39 Enhance the Selective Leaching of Aluminum Bronze procedures to: B2.1.37 Prior to the period of

" examine aluminum bronze materials exposed during extended operation inspection of the buried essential cooling water piping for evidence of selective leaching, CR 11-28986

• perform destructive examinations of one through-wall de-alloyed component per unit to determine the extent of de-alloying if components are identified as leaking during the ten year period prior to the period of extended operation, o give preference in the selection of the component to be destructively examined to a leaking weld with a backing ring that would be similar to the welds in buried ECW wrought aluminum bronze piping. If no leaking components are found during this period, destructive examination will be performed on the current inventory of leaking components that were removed from service prior to this period of extended operation,

" perform destructive examinations on up to an additional four leaking components (i.e. two per unit) during the period of extended operation, if through-wall leaks are observed during the period of extended operation, and

• if a leak from below-grade welds is discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination.