ML021650059

Part 1 of 2, San Onofre Nuclear Generating Station, Exigent Steam Generator Technical Specification Change, Proposed Change Number NPF-10/15-543

ML021650059
Person / Time
Site:	San Onofre
Issue date:	06/10/2002
From:	Nunn D Southern California Edison Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML021650059 (31)

Text

Dwight E. Nunn ISOUTHERN EDIS ON CALIFORNIA Vice President An EDISON INTERNATIONAL"*' Company June 10, 2002 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Docket Nos. 50-361 and 50-362 Proposed Change Number NPF-10/15-543 Exigent Steam Generator Technical Specification Change San Onofre Nuclear Generating Station Units 2 and 3

Reference:

SCE to NRC letter dated May 22, 2002,

Subject:

Proposed Change Number NPF-10/15-543, Exigent Steam Generator Technical Specification Change, San Onofre Nuclear Generating Station, Units 2 and 3 Gentlemen:

Enclosure 1 of this letter provides responses to NRC questions received on June 10, 2002 concerning the Southern California Edison (SCE) Units 2 and 3 amendment applications 217 and 202, Proposed Change Number (PCN) 543 (Reference). PCN-543 requested a change to the Technical Specification Steam Generator (SG) Tube Surveillance Program requirement 5.5.2.11 .f.1 .h to more clearly delineate the scope of the SG tube inspection required in the tubesheet region. Because Enclosure 1 contains information proprietary to Westinghouse, it is supported by an Affidavit (Enclosure 2) signed by Westinghouse, the owner of the information. The affidavit sets forth the basis on which the information may be withheld from public consideration by the Commission and addresses with specificity the consideration listed in paragraph (b)(4) of 10 CFR Section 2.790 of the Commission's regulations. Enclosure 3 are errata sheets for WCAP-15894, Revision 0, "NDE Inspection Strategy For the Tubesheet Region In SONGS Units 2 and 3," which was enclosed in the referenced letter.

P.O. Box 128P San Clemente, CA 92674-0128 949-368-1480 Fax 949-368-1490

Document Control Desk June 10, 2002 In addition, the exigent request for San Onofre Unit 2 is modified based on discussions with the NRC staff to request that this change be effective for only the next cycle of operation. A revised Technical Specification page is enclosed. (Enclosure 4)

If you have any questions please contact me or Mr. Jack L. Rainsberry at (949) 368-7420.

Sincerely,

Enclosures:

1A. Responses to NRC Questions (Proprietary) 1B. Responses to NRC Questions (Non-Proprietary)

2. Affidavit for the Proprietary Westinghouse Responses for the NRC Questions

3. Errata Sheets for Westinghouse Topical Report WCAP-1 5894, Revision 0 "NDE Inspection Strategy For the Tubesheet Region In SONGS Units 2 and 3" (submitted in reference)

4. Replacement Page for Unit 2 Technical Specifications (Attachment E of Enclosure 1 the Reference) cc: E. W. Merschoff, Regional Administrator, NRC Region IV A. B. Wang, NRC Project Manager, San Onofre Units 2, and 3 C. C. Osterholtz, NRC Senior Resident Inspector, San Onofre Units 2 & 3 S. Y. Hsu, Department of Health Services, Radiologic Health Branch

State of California County of San Diego Subscribed and sworn to (or affirmed) before me this J4 1t*x., day of ,9fAp. ,2002, by b1k t~M F:-- -(Ax)

MMLANE C-jHEZ COMMLbrý Z91 NOtcrYPubrc Corltorria Son Dk)go County

• COMM BOM Oct 14,2002 Signature of Notary P *b*li c

ENCLOSURE 1B Non-Proprietary Responses to NRC Questions on Proposed Change NPF-1 0/15-543 San Onofre Nuclear Generating Station Units 2 and 3

1. Please provide a brief description of steam generator including model, number of tubes per steam generator, thickness of the tubesheet, tube outside diameter and wall thickness, tube material (e.g., mill annealed alloy 600),

number of tube supports, design (e.g., lattice grid) of tube supports, tube support material, and tube support thickness.

STEAM GENERATOR DESCRIPTION SONGS Units 2 and 3 steam generators were designed and supplied by Combustion Engineering (CE). Each unit has two steam generators. The two steam generators in each Unit have equipment number designations of "88" and "1189".

SONGS Unit 2 entered commercial operation in August 1983.

SONGS Unit 3 entered commercial operation in March 1984.

Combustion Engineering did not give the steam generators of these units a model designation; they are referred to as "3410 Megawatt" steam generators.

Each San Onofre NSSS utilizes two steam generators which are vertical U-tube and shell heat exchangers approximately 65 feet in height with a steam drum diameter of 22 feet.

The steam generator is constructed of carbon and alloy steel pressure containing members and Alloy 600 tubing. The primary or high-pressure parts of the unit are the hemispherical head, the tube sheet and the tubes. A divider plate with tongue and groove construction and a stay cylinder separates the head into inlet and outlet chambers. A 42-inch entrance nozzle allows reactor coolant into the steam generator which passes through the heat transfer tubes and exits through two 30-inch outlet nozzles. The steam generator is supported by a skirt attached to the bottom head.

The secondary side of the steam generator consists of two cylindrical shells joined by a conical section and a hemispherical head. The tube bundle is enclosed by a baffle (shroud) which forms the downcomer annulus just inside the shell. The top of the baffle serves to support the steam separator deck.

The tube bundle consists of 3/4 inch tubes of various lengths. The tubes are arranged in rows with all tubes in a given row having the same length. The rows are staggered giving a triangular pitch arrangement. The shorter tubes, which have 1800 bends are at the center of the bundle in the first 18 rows. The vacant space (approximately 4 1/ inches) between the tubes in the first row is called the tube lane which is open through the tube bundle. The tube lane is the boundary between the hot leg side and the cold leg side of the secondary side of the steam generator. Longer tubes in the outer rows have double 900 bends.

Tubesheet The tubesheet is a 22 3/4" thick "High Strength Low Alloy" SA 508 steel forging and also includes 1/*" (min.) of corrosion resistant SB-1 68 cladding on the primary face.

Stay Cylinder The stay cylinder is the cylindrical supporting member within the steam generator primary bowl. The stay cylinder serves to reduce tubesheet flexure or "bow" from the influence of primary coolant pressure.

Tubing

1) Total number of tubes: 9350

2) Material: Alloy 600 High Temperature Mill Annealed

3) Outside diameter: 0.750"

4) Wall thickness: 0.048"

5) Tube pitch: Triangular

6) Rows 1 through 18 are U-bend type tubes. In all other rows, the upper portion consists of two 90 degree bends (square bends) and a horizontal span.

7) The tubes are explosively expanded ("Explanded") the full depth of the tubesheet.

Tube Support Structures The SONGS steam generator design employs the use of horizontal supports (eggcrates), diagonal supports (batwings) and vertical supports (vertical straps) to support the tubing. All tube support material is carbon steel (A-569 and A-570). The eggcrate elements are 1" and 2" in height and 0.090" thick. Eggcrates 01-07 are full supports. Eggcrates 08-10 are partial supports which do not extend across the entire tube bundle. A scalloped bar forms the non-peripheral edge of partial eggcrate supports.

All tubes are supported by 2 batwings. All tubes in rows >_R19 are supported by a combination of vertical straps.

The following figure depicts the general arrangement of the steam generator tubing and supports:

2. Clarify definitions of "joint length" and "tube engagement area length".

Specifically address whether these measurements are from the top of the tubesheet or from the bottom of the expansion transition. If from the top of the tubesheet, provide a Table depicting the distance from the top of the tubesheet to the bottom of the transition for each of the specimens.

As used in WCAP 15894-P, Rev. 0, joint length is the distance over which the tube and tubesheet have been mechanically joined by an explosive force imparted to the inside diameter of the tube. Its value varies with the sample being tested. As defined on page 19 of WCAP 15894-P, Rev. 0, tube engagement length is the tube to tubesheet joint length below the top of the tubesheet that provides a sufficient contact force to preclude pull out at 3NODP and to limit leakage at MSLB pressures. The required tube engagement area length for San Onofre is shown on page 60 of WCAP 15894-P, Rev. 0. The top of the joint starts at, and is measured from, the bottom of the expansion transition. In CE steam generators, the bottom of the expansion transition is consistently within a few tenths of an inch of the top of the tubesheet. (This is further clarified in the following response to Question 3.)

3. The inspection distance is specified from the top of the tubesheet. Are all tubes expanded such that the bottom of the expansion transition is located at the top of the tubesheet? If not, provide a histogram summarizing the distance from the top of the tubesheet to the bottom of the expansion transition.

The following histogram illustrates the distribution of the transitions.

It should be noted that these data are based on the midpoint of the transition.

The distance from the midpoint of the transition to the bottom of the transition averages 0.15".

The distribution of the transitions depicted in the histogram supports the statement in WCAP 15894-P that the process is consistently applied. All of the transitions are within 0.45" of the top of the tubesheet.

Expansion Transition Locations Relative to Top of Tubesheet (inches)

SONGS-2 Both SGs

>0.40 0 0.36 to 0.40 1 0.31 to 0.35 17

.n,nnxxx,nS VVVVVS9 0.26 to 0.30 1503 0.21 to 0.25 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxN 'XXXXXXXXXXXAf-iT-Q A

0.16 to 0.20 5111 i

0.11 to 0.15 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxNxxxxxxxxxxxxxxN C*.\\XXXXXXXXXXXXXXXX1 7X1P I Q V

0.06 to 0.10 1991 0.01 to 0.05 r 564 Top of Tubesheet I- p q 9

-0.04 to 0.00 S206

-0.09 to -0.05 g 52

-0.14 to -0.10 115

-0.19 to -0.15 116

-0.24 to -0.20 115

-0.29 to -0.25 I5

<=-0.30 0 I + + 4 4 0 1000 2000 3000 4000 5000 6000 Number of Tubes

4. A value of 4410 psid was used to correspond to the 3 times the normal operating differential pressure acceptance criterion. What was the secondary side pressure used in determining this value.

780 psia was used in determining the value. Steam generator secondary pressure is maintained above 780 psia.

For the most recent cycle of operation the minimum steam generator secondary pressure was greater than 805 psia.

5. Please provide a summary of all of the conservatisms in your analysis (if different than that on page 13 of WCAP-15894-P, Revision 1).

(Please note the version of WCAP-15894-P submitted was revision 0)

A list of several conservatisms are provided in WCAP 15894-P, Rev. 0 in Section 1.7. In addition, the following conservatisms are imbedded in the results provided in the report:

1. No credit was taken in the pull-out testing for the increased joint contact force due to differential thermal expansion. (Credit for this was, however taken for the leakage testing.)

2. No credit was taken in the pull-out testing for the increased joint contact force due to normal operating pressure; steam line break pressure; or 3NODP acting on the inside of the tubing. (Credit for this was, however taken for the leakage testing.)

3. The leakage tests that showed no leakage were conservatively assumed to have the minimum detectable leakage amount for the test apparatus.

4. The effect of tubesheet bowing was computed at the tubesheet location with the limiting loading.

5. The tube pull-out criterion was based on 3NODP which is significantly higher than the actual maximum DP a tube would experience during a main steam line break accident.

6. Please provide a description of the results of your inspections in the tubesheet region. Please clarify that all tubes with indications in the tubesheet were repaired (specifically address how axial indications detected by the bobbin in the lower part of the tubesheet were dispositioned). Please describe the size of the largest circumferential indication found this outage and in prior outages. Please provide the number of circumferential indications found.

6a. Please provide a description of the results of your inspections in the tubesheet region.

In the current inspection, 78 circumferential, 66 axial, and 3 volumetric indications were detected in the tubesheet region examinations. The tubes containing these indications were plugged or repaired by sleeving. Additionally, these indications were included in the screening process for in situ pressure testing and in situ leak testing. These (78/66/3) indications did not require in situ testing.

Of the 78 Circumferential indications 67 were located at the expansion transition. 11 were located below the expansion transition.

6b. Please clarify that all tubes with indications in the tubesheet were repaired (specifically address how axial indications detected by the bobbin in the lower part of the tubesheet were dispositioned).

The full length of the tubesheet was examined using the bobbin coil technique. All tubes with indications within the tubesheet detected by bobbin and confirmed by plus point are repaired either by plugging or sleeving. From the 3" above the top of the tubesheet to 5" below the top of the tubesheet on the hot leg, all tubes are examined with the Plus Point technique. All tubes with indications detected by Plus Point are repaired either by plugging or sleeving.

6c. Please describe the largest circumferential indication found this outage and in prior outages. Please provide the number of circumferential indications found.

1993 12 N/A N/A Pancake 1995 27 N/A N/A Pancake 1996 155 N/A N/A Plus Point 1999 99 57% 7% Plus Point 2000 102 50% 6% Plus Point 2002 78 28% 5% Plus Point N/A = Not available Percent Degraded Area (PDA) is presented here since it is a reflection of the tendency of the tube to sever.

7. With respect to tubesheet bow (and tubesheet hole dilation), what is the limiting "region" of the steam generator? Is it in the interior of the tube bundle or in the periphery? Please clarify if the allowance for tubesheet bow is for the worst "position" in the steam generator.

PWestinahouse Proprietary Information]

The tubesheet was considered as a solid plate with deflections considered over the entire plate. No regional variation credit was taken. The analysis was conducted on a worst position basis for tubesheet hole dilation which was determined from the original SONGS steam generator design report, CENC 1272. In the design report, a conservative classical interaction type of analysis was performed on the tubesheet, which also included the primary head, secondary shell, and stay cylinder. The divider plate, which would further reduce deflections was conservatively neglected. The worst position was determined to be [ ] inches radially from the center of the tubesheet. The outermost row of tubes is approximately 75 inches from the center of the tubesheet. Thus, this location is interior to the tube bundle.

8. Compare the Westinghouse and CE explosive expansion methods in terms of the resultant contact pressures (i.e., ability of the tube to resist pullout from the tubesheet). Does the CE method provide comparable contact pressures?

[Westinghouse proprietary information]

Based on a review of Combustion Engineering (CE) explansion joint development test reports, the CE explansion joint was designed to provide radial load similar to a rolled joint. The minimum value pull test load documented in WCAP 15894-P, Rev. 0 for a two inch specimen is [ ] lbf. The other two inch specimens have load values exceeding 5000 lbf which is more in line with rolled test results from the F* testing. The WEXTEX tube joint was not designed to provide a radial load at room temperature and pressure. The W* report provides values of [ ] and [ ]lbf pull-out loads for the two inch specimens.

The CE joint design exceeds the as-designed contact pressure of the WEXTEX joint. (Even including Specimen 21 from WCAP-15984-P, Rev. 0 would not change this conclusion.)

9. Describe the extent to which denting has occurred at San Onofre 2. If denting has occurred, discuss whether it would prevent/limit the potential for tube pullout. Describe whether any prior tube pulls provided any insights on the extent to which denting may limit the potential for tube pullout.

Dents have been detected by bobbin eddy current in the Unit 2 steam generators at tube supports. Approximately 8600 dented locations (5210 in SG 88 and 3412 in SG 89) were identified during the current inspection. While these dents are concentrated at the 5th, 6th and 7th tube support elevations on the hot leg side, dents can be found at most supports. Please note that a large fraction of tubes have no reported dents.

The San Onofre steam generators utilize an eggcrate type of tube support. This support type provides little or no resistance to tube pullout even at dented locations. Consequently, no credit has been assigned to dents reducing tube pullout.

In the outage which began in December 1996, three tubes including one tube with a dented support were removed for laboratory examination. Both the breakaway force and the pulling forces for the dented tube were bounded by those of the undented tubes.

Pcn543rai

ENCLOSURE 2 Affidavit for the Proprietary Westinghouse Responses for the NRC Questions

Westinghouse Proprietary Affidavit pursuant to 10 CFR 2.790 Page I of 2 I, Norton L. Shapiro, depose and say that I am the Advisory Engineer of CE Engineering Technology, Westinghouse Electric Company LLC (WEC), duly authorized to make this affidavit, and have reviewed or caused to have reviewed the information which is identified as proprietary and described below. I have personal knowledge of the criteria and procedures utilized by WEC in designating information as a trade secret, privileged, or as confidential commercial or financial information.

This affidavit is submitted in conformance with the provisions of 10 CFR 2.790 of the Commission's regulations for withholding proprietary information and in conjunction with the application of Southern California Edison Company for withholding this information. The information for which proprietary treatment is sought, and which document has been appropriately designated as proprietary, is Attachment I to Westinghouse Letter LTR-SGDA-02 174, "Response to NRC RAls on WCAP-15894-P," dated June 10, 2002. Pursuant to 10 CFR 2.790(b)(4) of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the information included in the document identified above should be withheld from public disclosure.

1. The information sought to be withheld from public disclosure is owned and has been held in confidence by WEC. It consists of data in responses to NRC Requests for Additional Information (RAIs) that support the acceptability of a proposed distance below the secondary face of the tubesheet for conducting non-destructive examinations in the San Onofre Nuclear Generating Station (SONGS) Unit 2 and 3 steam generators.

2. The information consists of analyses or other similar data concerning a process, method or component, the application of which results in substantial competitive advantage to WEC.

3. The information is of a type customarily held in confidence by WEC and not customarily disclosed to the public.

4. The information is being transmitted to the Commission in confidence under the provisions of 10 CFR 2.790 with the understanding that it is to be received in confidence by the Commission.

5. The information, to the best of my knowledge and belief, is not available in public sources, and any disclosure to third parties has been made pursuant to regulatory provisions or proprietary agreements that provide for maintenance of the information in confidence.

6. Public disclosure of the information is likely to cause substantial harm to the competitive position of WEC because:

a. A similar product or service is provided by major competitors of WEC.

b. WEC has invested substantial funds and engineering resources in the development of this information. A competitor would have to undergo similar expense in generating equivalent information.

c. The information consists of data that support the acceptability of a proposed distance below the secondary face of the tubesheet for conducting non-destructive examinations in the SONGS Unit 2 and 3 steam generators, the application of which provides a competitive economic advantage. The availability of such information to competitors

OWesfinghouse ~. ,.

~Wetinhoue 0

~inn*~,U~.a~

M~ulf! Afi,~... kflIC1jO,,L

.. .~. LIJ A trn mu *~~'~£C.i M

/

Page 2 of 2 would enable them to design their product or service to better compete with WEC, take marketing or other actions to improve their products position or impair the position of WEC's product, and avoid developing similar technical analysis in support of their processes, methods or apparatus.

d. Significant research, development, engineering, analytical, manufacturing, licensing, quality assurance and other costs and expenses must be included in pricing WECs products and services. The ability of WEC's competitors to utilize such information without similar expenditure of resources may enable them to sell at prices reflecting significantly lower costs.

e. Use of the information by competitors in the international marketplace would increase their ability to market comparable products or services by reducing the costs associated with their technology development. In addition, disclosure would have an adverse economic impact on WEC's potential for obtaining or maintaining foreign licenses.

Norton L. Shapiro Advisory Engineer Sworn to before me this day of. 2002

',, Public I )

My commission expires: ____ -_

ENCLOSURE 3 Errata Sheets for Westinghouse Topical Report WCAP-15894, Revision 0 "NDE Inspection Strategy For the Tubesheet Region In SONGS Units 2 and 3" (submitted in Reference)

Westinghouse Proprietary Class 2 Westinghouse Letter LTR-SGDA-02-174 Attachment 4 Westinghouse Report WCAP 15894-P ERRATA All changes are provided as underlined text in the change pages included in this Attachment.

1. Page 29, Section 3.3.2.3

2. Page 51, Section 5.1

3. Page 52, Section 5.2

4. Page 53, Table 5-1 and Table 5-2

5. Page 54, Figure 5.3 deleted

6. Page 56, Section 6.0

Westinghouse Proprietary Class 2 WCAP 15894-P Page 29 of 67 Section 3 Technical Approach Summary jacked out. Figure 3.11 is a photograph of the load test cell used to determine the pull-out force necessary to remove the tubes as a function of the tubesheet joint length.

All BE SG tubes that are leak tested were also pull tested as described above. Table 3-3 provides the test matrix for the BE SG tests.

3.3.2 Single Tube Mockups 3.3.2.1 Tubesheet and Tubing Specifications The single tube mockups consist of an 8" thick tubesheet 1.625" OD containing a single 0.75" OD tube. Approximately 6" of tube length extends out from the secondary face of the tubesheet The single tube specimen specification is shown on Figure 3.12. The tubesheet material is SA 508, Class 3 and the tubing is Nickel Alloy 600. Two tubing wall thicknesses were tested: 0.048" and 0.042". The tubing material properties were at the high end of the standard CE specification for yield strength (U8 . The standard yield strength specification for CE design steam generator tubes is 35 - 55 ksi. The single tube specimens are all from the same heat of material with yield strength of 54 ksi. The tubes were explanded into the simulated tubesheets (collars) using the standard Combustion Engineering method. Figure 3.13 provides a picture of the setup before explansion.

3.3.2.2 Drilled Tubesheet Hole Tubesheet drilling of all but a few steam generators manufactured by CE for CE designed units was done by a "gun-drill" process utilizing a cutter on the end of a rotating tube. Chips from tlh cutting process spiraled back from the cutting area via the flutes in the cutting tool and were carried away by cutting fluid injected into the cutting area. Cutting procedures on tool feed (cutting) rate and tool replacement frequency would have provided the specified tube hole surface smoothness and hole straightness. Excessive cutting rate causes tool wandering and scoring of the surface as the chip expulsion rate approaches capacity. Surface roughness was specified in manufacturing drawings as less thin 250 micro-inches (AA). Records of measurement techniques and typical as-built roughness are no longer available but the Boston Edison steam generator tube joints provide a bench-mark representation. Explansion process development documents indicate that surface smoothness better than the specification was not necessary or desirable. It was recognized through testing in the process development that surface roughness provided anchor points in the tubesheet joints and ensured good resistance to pullout.

3.3.2.3 Test Matrix Overview The test plan for single tube (collar) testing is shown in the Single Tube Test Matrix, Table 3-4 below. Not all tests in the plan were completed for various reasons as explained in the sections describing the test results.

Westinghouse Proprietary Class 2 WCAP 15894-P Page 51 of 67 Section 5 Leak Rate Test Results 5.0 LEAK RATE TEST RESULTS Leak rate tests provided data for determining the joint length necessary to meet the leakage criteria of 0.1 gpm per steam generator.

5.1 Boston Edison Steam Generator Leak Rate Results The Boston Edison leak rate data provides room temperature information of an as-built leak rate data from the tests conducted on 12 tubes in the BE steam generator mockup. Detailed data are provided in Appendix B. Figure 5.1 plots the average of three tests for each specimen and illustrates that the trend of the data is reasonable despite the scatter. These tests being at room temperature provide an indication of the variability of as-built steam generator joints. The leak rates of the individual tests ranged from a maximum of 2.40.10"5 gpm down to 4.05-10-6 gpm which is the value of I assigned pump stroke in a forty minute test. These tests were completed as a real-world benchmark for comparison to the single tube mockup data and provide an order of magnitude for the expected variability and the total leakage amounts as a function of joint length.

Some non-quantifiable factors that could have influenced the leak rate results include the mechanical jacking that was used to remove the Flow Distribution Baffle (FDB) from the assembly, and to a lesser extent, an MDM cutting influence. The jacking was completed before the tubes were MDM cut in the tubesheet region and would most likely have only affected those tubes that caused the tube to FDB interference fit that resulted in the difficulty in removing the FDB (discussed in Section 7). These factors would influence the results in a conservative direction by tending to weaken the joint tightness. Despite the possible non-quantifiable factors, the data appear reasonable because the variation is restricted to very small absolute values, i.e.,

on the order of 10-5 gpm.

The condition of the tubesheet precluded a confirmation of leakage by visual observation of water on the secondary face of the tubesheet because the line of sight view was obstructed.

However, testing of the single tube mockups, as described below, provided confirmation that the leakage indicated by the pump strokes was occurring through the tubesheet crevice and did not represent leakage through seals, fittings, etc. of the pressurizing system. A review of the individual test pressure versus time plots indicated that the leak rates generally decreased with time (interval between pump strokes increased). Possible reasons for this include:

"* the crevices above and below the MDM cuts were filling during the first parts of the test,

"* particulates from the MDM cutting were carried into and became lodged in the crevices, however, no particulates were noted in the post-test surface examinations, or

"* corrosion occurred during the tests (which would also occur during SG operation).

Thus, it seems likely that the crevices above and below the MDM cuts were filling with water during the first part of the test.

Westinghouse Proprietary Class 2 WCAP 15894-P Page 52 of 67 Section 5 Leak Rate Test Results 5.2 Single Tube Mockup Leak Rate Result Tables 5-1 and 5-2 provide the results of the leak rate tests as a function of joint length. The room temperature tests were conducted to compare the single tube mockups to the Boston Edison room temperature results to gauge the difference in the mockup configuration results to an as built steam generator condition.

Despite the fact that most of the tests resulted in data supporting reasonable NDE inspection lengths, some data do not fit with expectations. Figure 5.2 illustrates the single tube mockup data plotted with the BE SG data. The data except for specimen 10 is reasonably consistent and is indicative of a flat leak rate near the lower limit of measurement for the test system. The specimen 10 leak rate at approximately 23.10"5 gpm does not appear to be representative in the comparison of rough single tube mockup data with Boston Edison SG data.

The differential thermal expansion between Alloy 600 tubing and the carbon steel tubesheet is expected to be a significant factor in the joint force. Transient temperature changes during a design basis MSLB may play a role in lessening the effect resulting from initial SG pressure blowdown and the associated RCS cooling. However, the thermal capacitance of the tubesheet and the RCS reheat after several minutes in to the worst case transient will re-establish the joint force due to the greater expansion of Alloy 600 tubes. To evaluate temperature effects on the leak rates of tubes with flaws within the tubesheet, tests on two of the drilled hole mockups with nominal joint lengths of 3 and 3.5 inches were conducted at a temperature of a CE design lower end bounding normal operating temperature of 585*F. The specimen 7 NOT test indicates that the temperature effect does not significantly affect the leakage if the room temperature leakage is low, i.e., the joint is tight. The specimen 10 results show a significant decrease with the temperature increase. This indicates that if the room temperature leakage is relatively high, i.e.,

the joint is relatively loose, then the temperature effect is to significantly tighten the joint, thus confirming that the temperature effect is significant. Considering the thermal effects, all tests demonstrate that the leakage is less than the leakage limit of 0.1 gpm from 10% of the total number of tubes.

Westinghouse Proprietary Class 2 WCAP 15894-P Page 53 of 67 Section 5 Leak Rate Test Results Table 5-1 Single Tube Mockups: Leak Test Data @ Room Temperature Joint Average Specimen Length Pressure Temp Average Leakage x 10%

Number Target (PSI) (F) Leakrate of tubes per SG, (in.) (x 10-5 gpm) gpm 7 3 2596 70 0.8441 0.00785 9 3.5 2612 70 0.4004 0.00377 10 3.5 2595 70 22.5380 0.210 8 3.5 2597 70 4.3813 0.0408 11 4 2602 70 2.0128 0.0188 12 4 2639 70 0.5225 0.00492 Table 5-2 Single Tube Mockup: Leak Test Data @ NOT Specimen Joint Length Average Temp Average Leakage x 10%

Numer Target Pressure Temp Leakrate of tubes per SG, Number (in.) (PSI) (0 F) (x I0" gpm) gpm 7 3 2597 585 1.5361 0.0143 10 3.5 2609 585 5.276 0.0492

Westinghouse Proprietary Class 2 WCAP 15894-P Page 55 of 67 Section 5 Leak Rate Test Results Figure 5.2 Boston Edison SG and Single Tube Mockup Tests Averaged Leak Rates vs. Joint Length at Room Temperature t 5 S10 35

,H Joint Longt In.)

C-DI Fieure 5.3 Deleted

Westinghouse Proprietary Class 2 WCAP 15894-P Page 56 of 67 Section 6 Tubesheet Deflection Analysis 6.0 TUBESHEET DEFLECTION ANALYSIS The results of the single tube mockup samples pullout tests indicated an average pullout load of approximately 2,452 lbf per inch of engagement for the room temperature tests.

An increased contact force effect due to pressurization is demonstrated by the supplementary in situ pressure test (ISPT) type tests. The pullout load results used for the development of the deflection load are sufficient, but very conservative.

Of the samples listed in Table 6-I, only specimens 2 and 6 were used in the development of the average load of 2,452 lbf/in. The NOT samples results discussed in Section 4 demonstrate a reduction of load. Because the beneficial effect of the pressure contact was not available to add and it would be expected to have a greater effect than temperature, it was decided to disregard the "NOT specimens" for this analysis. All specimens with loads greater than 6,000 lbf were also excluded because they exceed the tube yield by a large margin and would incorrectly reduce the result. Further, on the basis of a review of the Boston Edison SG pullout load results, the one single tube mockup load value that was 2,000 lbf less than the average of all results was considered anomalous on the basis of bore surface variability in single tube mockup fabrication.

The best estimate contact load for tube explansion is based on using a coefficient of friction of 0.2, which is consistent with the W* application (10), and results in a pullout load of 2,452 lbf/in. The resulting radial contact load for tube explansion is approximately 12,260 lbf per inch of engagement.

An analysis of the tubesheet flexure stresses (19) and axial tube loads for normal operating differential pressure was performed. Tubesheet flexure reduces the effective contact load at the tube-to-tubesheet interface. For RCS pressures greater than SG pressure, the tubesheet flexes axially upward and the reduction in contact load is greatest at the top of the tubesheet. The contact load decreases almost linearly with depth into the tubesheet. Results of the single tube and tubesheet finite element analysis (4) indicated a total reduction in the contact load of 9,945 lbf for the region from the secondary face to a depth of 1.75 inches. For the 1.75-inch depth, the normal contact load for tube explansion is 21,455 lbf. But with the reduction, the net contact load is 11,510 lbf.

The net contact load of 11,510 lbf results in a frictional load of 2,302 lbf to resist tube pullout for the 1.75 inch depth. The resisting load exceeds the bounding pullout load criteria of 2,000 lbf determined at 3NODP. The results are considered very conservative.

It is concluded that a minimum depth of 1.75 inch will provide sufficient resistance to tube pullout to meet the structural integrity requirements.

ENCLOSURE 4 Replacement Page for Unit 2 Technical Specifications (Attachment E of Enclosure 1 the Reference)

Procedures, Programs, and Manuals 5.5 5.5 Procedures, Programs, and Manuals (continued) 5.5.2.11 Steam Generator (SG) Tube Surveillance Program (continued) e) Imperfection - An exception to the dimensions, finish, or contour of a tube from that required by fabrication drawings or specifications. Eddy current testing indications below 20% of the nominal tube wall thickness, if detectable, may be considered as imperfections; f) Repair Limit - The imperfection depth at or beyond which the tube shall be removed from service or repaired and is equal to 44% of the nominal tube wall thickness; Sleeves shall be removed from service upon detection of service-induced degradation of the sleeve material or any portion of the sleeve-to-tube weld.

g) Preservice Inspection - An inspection of the full length of each tube in each SG performed by eddy current techniques prior to service to establish a baseline condition of the tubing. This inspection shall be performed prior to initial MODE 1 operating using the equipment and techniques expected to be used during subsequent inservice inspections. These examinations may be performed prior to steam generator installation. Similarly, for tube repair by sleeving, an inspection of the full length of the pressure boundary portion of the sleeved area shall be performed by eddy current techniques prior to service. This includes pressure retaining portions of the parent tube in contact with the sleeve, the sleeve-to tube weld, and the pressure retaining portion of the sleeve.

h) Tube Inspection - An inspection of the SG tube from the point of entry (hot leg side) completely around the U-bend to the top support of the cold leg excluding the portion of the tube within the tubesheet (TS) below 5 inches from the secondary face of the TS.*

i) Unserviceable - The condition of a tube if it leaks or contains a defect large enough to affect its structural integrity in the event of an Operational Basis Earthquake, a loss-of-coolant accident, or a steam line of feedwater line break accident as specified in Specification 5.5.2.11.e.

• This exclusion is for Unit 2, Cycle 12 operation only.

(continued)

SAN ONOFRE--UNIT 2 5.0-18 Amendment No.