Text

Attachment 4 - MHI Document L5-04GA564 - Tube Wear of Unit-3 RSG, Technical Evaluation Report
	ML12285A265
Person / Time
Site:	San Onofre
Issue date:	10/01/2012
From:	; Mitsubishi Heavy Industries, Ltd, Southern California Edison Co
To:	; Office of Nuclear Reactor Regulation, NRC Region 4
References
	L5-04GA564
	Download: ML12285A265 (142)
	v • d • e

SOUTHERN CALIFORNIAEDISON 0 An EDISOQ INIRNI't 4TI ALZ Compnny SONGS Unit 2 Return to Service Report ATTACHMENT 4 MHI Document L5-04GA564 Tube Wear of Unit-3 RSG Technical Evaluation Report[Proprietary Information Redacted]

I Non-proprieta Version I fi 3 (P.1)San Onofre Nuclear Generating Station, Units 2 & 3 REPLACEMENT STEAM GENERATORS Tube wear of Unit-3 RSG -Technical Evaluation Report Supplier Status Stamp VP02:3-617-1-M1 538 0 " IIN jcN/A DESIGN DOCUMENT ORDER NO. 800873488 REFERENCE DOCUMENT-INFORMATION ONLY E]VIRP IOM MANUAL MFG MAY PROCEED: EYES []NO W/A STATUS -A status is required for design documents and Is optional Ior reference documents.

Drawings are reviewed and approved .for arrangements and conformance to specification only. Approval does not relieve the submitter from the responsibility of adequacy and sultabilty of design, materials, and/or equipment represented.

Bj. APPROVED.APPROVED EXCEPT AS NOTED -Make changes end resubmil.03. NOT APPROVED -Correct and resubmit for review. NOT for ield use.APPROVAL- (PfI.NT I GN / 7A-N) t RE: ") b U L'.J L ',,./.(),j q .__ /FLS: Other. .* ".. ..SCE DE(123) 5 REV. 3 07111

REFERENCE:

S0123-XXIV-37.8.26 Purchase Order No. 4500024051 Specfcation No. SO23-617-01R3 Nuclear Plant Component Designing Department Steam Generator Designing Section-r AMTSBUISHi

-HEAVY INDIUSTRIES, LTD.Page 1 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version ) (P.2)Document No.L5-04GA564(9)

AF*I Revision History No. Revision Date Approved Checked Prepared 0 Initial issue See cover sheet Revised in accordance with RSG-SCE/MHI-12-5698 1 (Since this report has been wholly revised, the revision bar is omitted)-Revised in accordance with RSG-SCE/MHI-12-5714-Revised Appendix-1 0 by 2 using the latest ATHOS outputs-Added Appendix-16-Revised in accordance with RSGLSCE/MHI-12-5728 3 -Revised Appendix-8 and 9 iný accordance with Expert Panel's comments-Revised the main report wholly-Revised Executive Summary and Section 5.2.2 6 -Revised in accordance with RSG-SCE/MHI-12-5745

-Revised in accordance with 7 RSG-SCE/MHI-12-5757 and RSG-SCE/MHI-12-5762

-Revised in accordance with RSG-SCE/MHI-12-5775 8 -Revised Appendix-9 to be consistent with the current full bundle model analysis cases MI TSUBISHI HEAVY INDUSTRIES, LT Ij Page 2 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version) (P.N3)Document No.L5-04GA564(9)

No. Revision Date Approved Checked Prepared-Revised in accordance with RSG-SCE/MHI-12-5786

-Revised Section 4.1.2 and 9 4.1.3-Added Fault Tree Evaluation in Section 6-Undeleted Appendix-16 MI TSUBISHI HEAVY INDUSTRIES, LTD.Page 3 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version )SJ (P.4)Document No.L5-04GA564(9)

At Table of Contents 1 .In tro d u c tio n ....................................................................................................................

1 0 2. Sum mary of RSG Design for SONGS .......................................................................

10 2.1 Overall RSG Design ...........................................

10 2.2 Tube Bundle Design ...........................................................................................

11 3. Description of Events ................................................................................................

13 3 .1 U n it-2 ......................................................................................................................

1 3 3.1.1. Abstract ......................................................................................................

13 3.1.2. Sequence of Events ....................................................................................

13 3.2 Unit-3 ..... .................................

...............

14 3.2.1. Abstract ......................................................................................................

14 3.2.2. Sequence of Events ....................................................................................

14 4. Investigation of W ear Condition

................................................................................

15 4.1 ECT Inspection Results .......................................................................................

15 4.1.1. Types of Tube W ear ..................................................................................

18 4.1.2. Tube Wear in Unit-2 (for reference only) .........................

50 4.1.3. Tube W ear in Unit-3 ....................................................................................

52 4.2 Visual Inspection Results of the Tube Bundle .....................................................

54 4.2.1. Observations Common to Unit-2 and Unit-3 ........................

54 4.2.2. Observations in Unit-3 ..................................................................................

54 4.2.3. Observations in Unit-2 ..................................................................................

54 5. Mechanistic Cause Analysis ....................................................................................

57 5.1 Thermal Hydraulic Condition in the Secondary Side .........................................

57 5.2 Evaluation of U-bend Supports Condition

.........................................................

64 5.2.1. Out-of-Plane Direction Support ...................................................................

64 5.2.2. In-Plane Direction Support .........................................................................

64 5.2.3. Differences between Unit-2 and Unit-3 .......................................................

65 6. Tube W ear Causes .......................................

I .............................................................

70 6.1 Type 1 W ear (TTW ) ..........................................................................................

71 6.2 Type 2 W ear (AVB wear) ....................................................................................

71 6.3 Type 3 W ear (TSP wear) .....................................................................................

73 6.4 Type 4 W ear (RB wear) ......................................................................................

73 7 .C o n c lu s io n s ...................................................................................................................

8 1 8. Countermeasures for Return to Service ..................................................................

82 8.1 Tube Plugging .....................................................................................................

82 8.1.1. Type 1 W ear ................................................................................................

82 8.1.2. Type 2 W ear and Type 3 W ear .....................................................................

82 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 4 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version )I: Ii (P.5)Document No.L5-04GA564(9)

At 8 .1.3. Type 4 W ear ...............................

.........

....................................................

..8 2 8.2 Operating at a Lower Thermal Power ................................................................

84 9. References

.................

......................................

................

86 Appendices Appendix-1 Appendix-2 Appendix-3 Appendix-4 Appendix-5 Appendix-6 Appendix-7 Appendix-8 Appendix-9 Appendix-1 0 Appendix-1l Appendix-1 2 Appendix-1 3 Appendix-14 Appendix-15 Appendix-1 6 ECT Data Evaluation of tubes with wear around Retainer Bar .............

1-1 FEI Evaluation of Tube Straight Portion for Unit-2/3 .............................

2-1 FEI Evaluation of Tube U-bend Portion for Unit-2/3 ..............................

3-1 Investigation of Unit-2/3 Manufacturing and Inspection Records ..........

4-1 Analytical Simulation of Tube Bundle Rotation and Hydro Static Test ....... 5-1 Investigation of ISI ECT Data for AVB Support Condition for Unit-2/3 ....... 6-1 Visual Inspection Results for U-Bend Region for Unit-2/3 ....................

7-1 SG Tube Flowering Analysis for Unit-2/3 ..............................................

8-1.Simulation of Manufacturing Dispersion for Unit-2/3 ............................

9-1 SG Tube Wear Analysis for Unit-2/3 ........................................................

10-1 (D e le te d ) ........................................

.......................................................

1 1 -1 Thermal Hydraulic Evaluation of Area Plugging ......................................

12-1 (D e le te d ) ...............................................................................................

1 3 -1 Analytical evaluation of the impact on the Tube Support Plate and Tube Bundle due to Tubesheet deflection during Divider Plate detachment

.... 14-1 (D e le te d ) ...............................................................................................

1 5 -1 Fatigue Evaluation of the Tube due to In-Plane Vibration

.......................

16-1 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 5 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I J (P.6)Document No.L5-04GA564(9)

Ak 2A, 2B, 3A, 3B: 3D: Active support: ATHOS: AVB: B01 -B132 / AVBO1 -AVB1 2: B05 and B06: Col: CDS: ECT: FEI: FIV: Free-span:

G-value: Acronyms and Definitions Unit 2 SGs A (E089) & B (E088) and Unit 3 SGs A (E089) &B (E088)Three-dimensional, Tube support at AVB or TSP, which prevents tube motion in the in-plane and out-of-plane directions An EPRI sponsored thermal hydraulic computer program for steam generator flow analysis Anti-Vibration Bar AVB designations with B01 the first above TSP #7 on the hot leg side Cross-section through the U-bend parallel to AVB B05 and B06 Tube column number Certified Design Specification of SONGS Unit 2&3 RSGs (S023-,617-01, Revision 3)Eddy Current Testing Fluid Elastic Instability Flow Induced Vibration Tube section between supports Tube diameter in the U-bend region aligned with tube-to-AVB intersections MITSUBISHI HEAVY INDUSTRIES, LTD.Page 6 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version II ) (P. 7)Document No.L5-04GA564(9)

At Thermal-hydraulic conditions:

The term "thermal-hydraulic conditions" refers to flow velocity, void fraction (steam quality) and'hydro-dynamic pressure Inactive support: Tube support at AVB or TSP, which does not prevent tube motion in both in-plane and out-of-plane directions ISI: In-service Inspection IVHET: MHI tube wear analysis program MHI: Mitsubishi Heavy Industries N: Newton, force (1N equals 0.2251bf)P/D ratio: Tube pitch-to-diameter, ratio PSI: Pre-service Inspection RB Retainer Bar R100C88: Tube address (Row 100, Column 88)RSG: Replacement Steam Generator SCE: Southern California Edison SONGS: San Onofre Nuclear Generating Station TSP: Tube Support Plate TTW: Tube-to-Tube Wear T/H Thermal and Hydraulic TSP #1-TSP #7: Tube support plate numbers from the lower most tothe upper most MITSUBISHI HEAVY INDUSTRIES, LTD.Page 7 of 474 S023-617-1-M1538, REV. 0 Non-proprietaryVersion I ,) (P.8)Document No.L5-04GA564(9)

Executive Summary On January 31, 2012, during the first cycle after steam generator replacement, San Onofre Nuclear Generating Station (SONGS) Unit 3 was shut down due to indications of a steam generator tube leak. Steam generator tube inspections confirmed one small leak on one tube in one of the two steam generators.

Further inspections of 100% of the steam generator tubes in both Unit-3 steam generators discovered unexpected wear, including tube-to-tube as well as tube-to-tube-support structural wear.Tube wear was found in the tube free span sections, at anti-vibration bars (AVBs), at Tube Support Plates (TSPs) and at retainer bars, and was labeled as follows: (i) Type 1 (Tube-to-Tube Wear)(ii) Type 2 (AVB wear)(iii) Type 3 (TSP wear)(iv) Type 4 (Retainer bar wear)The cause of the first 3 types of tube wear is tube vibration.

The causes of tube vibration are the thermal-hydraulic conditions in the SG secondary side and the condition of the tube bundle supports.

Type 4 tube wear is due to vibration of the selected retainer bars, rather than the tubes.Structures in a two-phase flow field have lower resistance to vibration when the fluid void fraction (and hence steam quality) is high. High void fraction (high steam quality) results in the two-phase flow mixture having low density, which in turn results in a high velocity of the two-phase flow and in a low damping factor. Consequently, the dynamic pressure, which is a function of the flow velocity squared, increases.

As the dynamic pressure is a major factor causing the structures in the flow field to vibrate, it is more likely for the structures to vibrate when the void fraction (steam quality) is high .(as it affects both the flow velocity and the damping factors).Based on the investigation of the correlation between the void fraction (steam quality) and the number of tubes with wear in a given void fraction region, a strong correlation between the void fraction (steam quality) and the percentage of tubes with wear was identified.

Consequently, it is concluded that the thermal-hydraulic conditions in the SG secondary side, namely high void fraction (steam quality) and high flow velocity, along with lack of sufficient IA in-plane tube support, discussed next, are the main causes of the excessive tube vibration and unexpected wear in the SONGS Unit 2 and Unit 3 SGs. The higher than typical void fraction is a result of a very large and tightly packed tube bundle, particularly in the U-bend, MITSUBISHI HEAVY INDUSTRIES, LTD.Page 8 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I ( J (P.9)Document No.L5-04GA564(9)

At with high heat flux in the hot leg side.Contemporary experience shows that out-of-plane vibration of the SG U-tube is more likely to occur than in-plane vibration, because tube U-bend natural frequency in the out-of-plane direction is lower than natural frequency in the in-plane direction.

In the design stage, MHI assumed that the tube support in the out-of-plane direction with "zero" tube-to-AVB gap in hot condition was sufficient to prevent tube from becoming fluid-elastic unstable during operation.

But, the recent SONGS experience shows that the flat bar AVBs does not provide friction forces required to prevent tubes from vibrating in the in-plane direction and eventually becoming fluid-elastic unstable under high local secondary thermal-hydraulic conditions such as in the SONGS RSGs. In addition, MHI concludes that in the Unit-3 RSGs low tube and AVB fabrication dimensional dispersion causes that the tube-to-AVB contact forces are not sufficient to prevent the in-plane motion of tubes.In order to ensure the structural integrity of the tubes after restarting the plant, all tubes which have a potential for. losing their integrity during the next operating period should be plugged and thermal power output of the plant should be decreased.

Plugging for the Type 1 wear should include not only the tubes with the Type 1 wear but also tubes which are susceptible to the Type 1 wear, for preventative reasons. Plugging for the Type 2 and 3 wear should include the tubes with wear equal to, or greater.than, 35% in accordance with Technical Specifications.

Plugging for the Type 4 wear should include 94 tubes which are adjacent to the retainer bars.Decreasing the thermal power output will improve thermal-hydraulic conditions (will lower flow velocities and void fractions in the critical tube bundle U-bend region) and thus will reduce the possibility of the occurrence of tube fluid-elastic instability (FEI) leading to unacceptable tube wear.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 9 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version {( ] (P.10)Document No.L5-04GA564(9)

At 1. Introduction After approximately 11 months of power operation following the steam generator replacement, SONGS Unit-3 underwent an unplanned shut down on Jan. 31, 2012 as a result of leakage of primary coolant to the secondary side from a tube in the 3B (3E-088) steam generator (SG).The maximum leakage rate was at approximately 82 gallon/day

(-13 liters/hour).

Subsequent investigation revealed that the direct cause of the leakage was tube-to-tube wear.At the time of the Unit-3 leak, SONGS Unit-2 had already completed one cycle of power operation

(-22 months) after the steam generator was replaced in the refueling outage since Jan. 9, 2012. Eddy-Current Testing (ECT) inspections were performed on all tubes in both Unit-3 SGs and wear indications on many of the tubes were found. This report presents the evaluation of the mechanistic cause of tube wear, and the countermeasures required for Unit-3 return to service.2. Summary of RSG Design for SONGS 2.1 Overall RSG Design The SONGS RSGs were specified, designed and fabricated as replacements on a like-for-like basis for the original steam generators in terms of fit, form and function with limited exceptions, and were replaced under the 10CFR50.59 rule. The CDS for the design and fabrication of the RSGs (S023-617-01, Revision 3) specified the limiting design parameters and materials.

Thus, replacement steam generator design with 3/4" tube diameter arranged in 1" triangular pitch, which was the same as in the original steam generators, and the larger heat transfer area than in the original steam generators, was optimal. The, other parameters/materials not specified by CDS were established/

selected in the design process. The SONGS RSGs were designed and fabricated to achieve an "effective zero gap" as required by CDS Rev. 3 in order to minimize its potential for tube wear. The CDS also states that the tube support/tube bundle assembly shall be fabricated such as to ensure no damage to the tubes and subsequent operation of the RSG with minimal vibration.

MITSUBISHI HEAVY INDUSTRIES, LTD.Page 10 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version) (P.11)Document No.L5-04GA564(9)

AO 2.2 Tube Bundle Design The major concern with the large U-tube SGs is their propensity for tube wear in the tube bundle U-bend region. Consequently, minimizing tube wear was given the first priority in the SONGS RSG specification, design and fabrication, and the tube support design and fabrication was discussed by MHI and SCE in numerous design review meetings.

As a result, the tube bundle U-bend support design and fabrication was as follows: 1) Six (6) V-shaped AVBs (three sets of two) were provided between each tube column.2) The AVB thickness was set such as to provide an effective "zero" tube-to-AVB gap under operating (hot) conditions.

3) The AVB end-caps were welded to the retaining bars with the U-bend in the gravity neutral position to achieve uniformity of the gap size and AVB parallelism, using spacers between the AVBs sized based on a mockup test.The tube bundle and AVB structure configuration and components (AVBs, retaining bars, bridges and retainer bars) are shown in Fig.2-1. MHI investigated field experience with U-bend tube degradation using INPO, NRC and NPE data bases, and concluded that tube wear in the operating U-tube SGs was mostly being caused by out-of-plane tube motion. Consistent with this and Reference 7, only out-of-plane vibration of the SG U-tubes was evaluated because tube U-bend natural frequency in the out-of-plane direction is lower than natural frequency in the in-plane direction and out-of-plane vibration is more likely to occur than in-plane vibration.

No SG problems stemming from in-plane tube motion were identified by MHI and thus MHI concluded that the design and fabrication processes described above were sufficient for minimizing tubewear in the SONGS RSGs.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 11 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I ( ) (P.12)Document No.L5-04GA564(9)

Aw L~IJ Bridges E~nd Cap Retaine BarJ Retaining Ba I LAI1L Fig.2-1 Tube Bundle and AVB Structure Configuration MITSUBISHI HEAVY INDUSTRIES, LTD.Page 12 of 474 S023-4 617-1-M1538, REV. 0 Non-proprietary Version I ( ]J(P.13)Document No.L5-04GA564(9)

3. Description of Events 3.1 Unit-2 3.1.1. Abstract During the first refueling outage following steam generator replacement, ECT inspection of the unit 2 steam generator tubes identified a total of 10 tubes with wear depths of 28 to 90% of the tube wall thickness.

Six of the affected tubes were located adjacent to the retainer bars. The retainer bars are part of the floating anti-vibration bar (AVB) structure that supports the U-bend region of the tubes. The remaining tubes had detectable wear associated with AVB support points elsewhere in the AVB structure.

3.1.2. Sequence

of Events Fall of 2009 The original Combustion Engineering (CE) SGs were replaced with MHI SGs during the Cycle 16 Refueling Outage.May, 2010 Unit 2 completed the Cycle 16 Refueling and Steam Generator Replacement outage and returned to service at nominal 100% reactor power.January 9, 2012 Unit 2 started the Cycle 17 Refueling Outage.February 5, 2012 Routine ECT inspections of the SGs identified wear indications greater than 35% at two tube locations adjacent to the retainer bars.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 13 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I) (P.14)Document No.L5-04GA564(9)

At 3.2 Unit-3 3.2.1. Abstract During the first cycle after steam generator replacement, on Jan.31, 2012, Unit 3 was shut down due to indication of a steam generator tube leak. Steam generator tube inspections confirmed one small leak on one tube in one of the two steam generators.

Continuing inspections of 100% of the steam generator tubes in both Unit-3 steam generators discovered unexpected wear, including tube-to-tube as well as tube-to-tube-support wear.3.2.2. Sequence of Events Fall, 2010 The original CE SGs were replaced with MHI SGs during the Cycle 16 Refueling Outage.February, 2011 Unit 3 completed the Cycle 16 Refueling and Steam Generator Replacement Outage and returned to service at nominal 100% reactor power.January 31, 2012 During 100% power operation, a high radiation alarm from the condenser air ejector line revealed a primary-to-secondary leak in a SG. SONGS operators responded by rapidly reducing power and then shutting down the plant.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 14 of 474 S023-617-1-M1538, REV. 0 I Non-proprietarv Version I () (P.15)Document No.L5-04GA564(9)

AO 4. Investigation of Wear Condition 4.1 ECT Inspection Results The basis of ECT data evaluations in this report (except Table 4.1.2-1 and Table 4.1.3-1) is described in Appendix-3 of Reference 8.Table 4.1..2-1 and Table 4.1.3-1 are based on the information provided by SCE (Reference 9 IA and 11).Wear indications obtained from ECT inspection are shown in Fig.4.1-1 and 4.1-2.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 15 of 474 S023-617-1-M1538, REV. 0 ECT Result I J 7 of SG2A Leciend _________0: No Indication

......___.-_-0: Between 5-10% _______.....

__* -Between 11-20%O: Between 21-30% I .*Between 31-40% -.:Above 41% %__ ._ _0 Location of Retainer Bar -Wear Indication (4tubes) ;, Location of Free Span Wear Indication (2tubes)[~ lll il ll i~ l] i~ ll il~ Il l l l i~Co W z V C (n)m SA)I ECT Resu of SG2B Legend oNo In*Bet*Bet o. Bew*. Bet 0: Abov dication veen 5-10%een 11-20% ..een 21-30% _ -Feen 31-40%TeeCnt iSN"-e41% ... -4. .on (21 ) '~Fig.4.1-1 Tube Wear Condition in SONGS Unit-2 z 0 0 CD CD Cn 0 0: 0 C (D 01 0)CF)-0 Location of R Wear Indicatio Page 16 of 474 S023-617-1-M1538, REV. 0 ECT Result of SG3A Legend No Indication

Between 5-10%* Between 11-20%o: Between 21-30%* Between 31-40%* .Above 41%0 Location of Retainer Bar Wear Indication (Itube)NE, T 1-1 1 T 1-1 1 1 1 1 1-1 1 T-1 I WIT L 4ý Aý-4 (A C W z a~C CA)-4 m SIC C ---?- .-7-. -7 11..Ef~fA Legend ,L) : No Indication

Between 5-10%:Between 11-20%/o: Between 21-30%* Between 31-40%* : Above 41%0 Location of Retainer Bar Wear Indication (3tubes)z 0 0 CD C<D 0 0 0 C 3 CD (0-4 I 1ME' UIE IX %1 TJJE LANE Fig.4.1-2 Tube Wear Condition in SONGS Unit-3 Page 17 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version ( J (P.18)Document No.L5-04GA564(9)

Ak 4.1.1. Types of Tube Wear Tube wear indications were found in the tube free span sections, AVB region and TSP region and were grouped into 4 types as follows: (i) Type 1 (TTW)Wear in the tube free-span sections between the AVBs located in the U-bend region. Most of the tubes with this type of wear have also wear indications at AVBs and TSPs. In this case, it is considered that the entire tube, including the straight leg, was vibrating excessively.

These tubes are shown in Fig.4.1.1-1.(ii) Type 2 (AVB wear)Wear at the tube-to-AVB intersections only with no wear indications in the tube free-span sections.

Some of these tubes have wear indications at the TSPs as well.In this case, it is considered that mainly the U-bend section of the tube was vibrating.

These tubes are shown in Fig.4.1.1-2.(iii) Type 3 (TSP wear)Wear at the tube-to-TSP intersections only in the straight section of the tubes. In this case, it is considered that only the straight section of the tube was vibrating.

The tubes with wear at TSPs without wear in the U-bend section are shown in Fig.4.1.1-3; the tubes with wear at TSPs and with wear in the U-bend section are shown in Fig. 4.1.1-4).(iv) Type 4 (RB wear)Wear at the AVB structure retainer bars in the tube U-bend section. These tubes have no wear indications in the free span, at AVBs or at TSPs. In this case, it is considered that the retainer bar itself was vibrating and the tube was not vibrating.

These tubes are shown in Fig.4.1.1-2 and in Appendix-1.

Table.4.1.1-1 Wea.r Type Locations Wear Location Wear Pattern Free Span AVB TSP Retainer Bar Type 1 (TTW) Yes Yes (Yes) No Type 2 (AVB wear) No Yes (Yes) No Type 3 (TSP wear) No No Yes No Type 4 (RB wear) No No No Yes Yes : Wear indication was found (Yes): Wear indication may be present since some tubes with AVB wear indications have no indications at TSP locations No : No wear indication Tube wear indications at each AVB and TSP elevation for all wear categories are shown in Page 18 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I II J(P.19)Document No.L5-04GA564(9)

AF Fig.4.1.1-5, 4.1.1-6, 4.1.1-7 and 4.1.1-8.Page 19 of 474 S023-617-1-M1538, REV. 0 nCKlr%S z 0i C (A Fn Ro Ro Ro Ro Ro Ro Ro Ro R.n R R Fc Fc F F RF RF Fc Fc Fc Fc Fc Fc Fc Fc Fc O- ,0TTW 11 , =:TTW 21; ; O :T'FW 31 o-121 --.. .-o,,.- 6 P-- i ,)

I'W > ,4.w 1 ."J .... .. ... .11 -i 1-ow- 10 --4-t ...i --i -+ --Row-S L -j__j Iýo-71 4 1--R.-I-10%-20%/30%40%41%z 0 0 CD Dil`0, CD CD)C)CYO 5 0 6 0 0 ) z0 0 oo_3 5 -3 S .. F z z z -3 z 'a ' z 0 Fig 4.1.1-1(1/2)

Tubes with TTW indications in U-bend region Page 20 of 474 S023-617-1-M1538, REV. 0 3B-SG-I C Cor z M1"-I m Pj Ro-141 LEGEND.... 0 : 0%R-136 I i I T 0' ftf I T ,o , r -I I-- T 0 R,131 I -T W I -10%12. --J--J--- TTW 11 0Y R-126 I -~ -L0 I-0( ' -L 1 -20%0 I TTW 21 -30%R I I I I I o% 0 6oo 0o - -TTW 31 -40%R j 1 J J --TTW > 41%Rw-101 T r -I ---I RO-96 , I I Row-81 0 4 --A --1 Ro-11 -~~ --- -00 -7'I Row-81 Ii 2-( Ro-71 -f Row-66o o0I Ro-"61 _ L -I Ro'-56I Ti Row-51 rr I Ro-46 -0i Ro-41 Ro-36 Row-31 Ro-20 Ro-21 Row-I I Ro-1 a o o -o 7 -o 3 o o o o o6 -o o3 o 3 o o o5 o o o "a o5 7 -a o5 o o o3 o ooooooo oC oC

o 0 0 ~o o 00o o0 o 0 i 0 0 0 0 00 00i , 0000 0 0 00 i 2, i 0 i 0 0 z 0 0 CD 0, C-)C: 0 CD C)C3)-Fig 4.1.1-1(2/2)

Tubes with TTW indications in U-bend region Page 21 of 474 S023-617-1-M1538, REV. 0 C (A-4 X ffn Ro-11t t i --Ro..I-48F r --I I T F 9 R_ 11 -L ---4 Row-0 -J ----Row-9 -4*LEGEND-~0 --- AVB I 10%---*:AVB 11 20%IAVB 21 30%0: "AB31 40%z 0 0 CD CD, 0, 0 CD z 0-p.GO)o o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 Fig 4.1.1-2(1/2)

Tubes with wear indications at AVBs and at retainer bars Page 22 of 474 S023-617-1-M1538, REV. 0 3B-SG CI Ca m C CO)-4 M ffi'0,~0IILEGEND R-3 L --- -:AVB 1-10%R-126 :AVB I11 20%dY' o~ 000 0 I AVB 21 -30%R.-I 16 0:AVB 31-40%........ .~ *:AVB >41%R._l ~~ ~ I SJJ-R-9 J9 -J I Row-AR Row-701 0 -Row-56 ~ 3 ~ ~ c g 0 ~Ro-51 f FS Row-46 ~so ~Row-2 Ro o o o o--2o o o oo1 i~0 0 Ro 1 ---) -) --) C ) C ) C ) 0 C ) 0 C ) C) C ) C ) C ) C ) C ) C )z 0 0 A--'0 M.CD*-0 0 3 CD C)>LD 0)0,'j Fig 4.1.1-2(2/2)

Tubes with wear indications at AVBs and at retainer bars Page 23 of 474 S023-617-1-M1538, REV. 0 3A-SG z X m Rw-1 41 Rowi 35 Ro-I 31 Ro- 126 Ro-121 Ro-I IS Ro-I 1l Row-i 06 R-101I Ro-S6 Row-SI Row-SR Row-Si Ro-76 Ro-71 Row-SR Row-6I Row-56 Row-5I Ro-46 Ro-41 Ro-36 Ro-31 Ro-26 Ro-21 Row-IS Ro-I I Row-S Row-I I I I I I I I I I I I i-------------

I I I I I 0 4... -.4 --.1. --I. --L.---.4 --I. --I I I r I I I 0 I ~ ~IS~0,~0 ~ --S@0,,0 0 0 60 I"l "i--T--r I- --I T-.. 1.I _ ._ fl4-- -C-_ L,. _ 1_ _ _1 _--0 00 + 0 00 ,.0~0 11-~ I. *:TSP 11 20%0*~ -- -- T 00 z 0 7I 0 CD 0 0 3)CD C-)4h.~0S,-'-------------- a -a 73 'a 7 oo 'a6*6--o ---------------S --S S S S S S ..a Fig 4.1.1-3(1/2)

Tubes with wear indications at TSPs only Page 24 of 474 S023-617-1-M1538, REV. 0 3B-SG Co Ca m z C m-~LEGEND I I I 0I 0%*:TSP 1 10%*:TSP 11 '20%-t t z 0 CD 0, CD 03 Fig 4.1.1-3(2/2)

Tubes with wear indications at TSPs only Page 25 of 474 S023-617-1-M1538, REV. 0 3A-SG F~Nn iA (A z X Fn (A p Ro-141 .-- --- ---- -- -- ------ -' -'-- -- -.....-R-131 :TSP 1 _10%Row-31 i I :TSP 11 20%TSP 21 -30%1-2 1 -1 1- l : TSP 31 40%R- 111 -1, -1 , ,:TSP > 41%Row-I3.t d R-90 R 8I /Row-t4 I--÷ --: Ro-86 I 1--- I Row-41 - -t Ro-36 --", Rw-31 --jI Row-26 ---Row-21 ---Ro-16 2 1%Ro-I I Row-41 ....Ro33 _5 6_0 yo-S z 0 7i 0 CD C<D 0 0 a, 3 CD 0>,.Lpa Fig 4.1.1-4(1/2)

Tubes with wear indications at TSPs and TTW indications Page 26 of 474 S023-617-1-M1538, REV. 0 3B-SG R w- 141 ............................- --LE G END Ro13 W , ,TSP 1 -10%Ro 13 ----I- --i- -i----------

ITS I I?Ro,-126--

--- I , ...... r.I r:TSP 11- 20%I ' I I I I :TSP 21 -30%Row-121 f- -i ---.I- -, 1 J --I -, ---O:TSP 31 -40%Row-11 I I I I I J I -O:TSP > 41%kR-RT\ L-- -' -r--, m Row-76 k----T I- -- ---- --I"CA Ro0*81 0 I I I I I Row-71I -r- --i

C *000 '--d -D- Q R-66 z Row-6I -L S Row-56 rn Row-51G ----C R-46 rI Ro-41 Row-I36 --, Ro-31 Row-2G 00IR-21 i Ro-16 : RoC o1I Z Rosy-G t-~0GCC ~ C '~ 0 '4 >0 0 > ' I < 0 C"0CI ~C R-1;-a _5 _0 C_0 L-a __5 C5 -3 _ 3 Fig 4.1.1-4(2/2)

Tubes with wear indications at TSPs and TTW indications 0 Page 27 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I) (P.28)Document No L5-04GA564(9) x 13A-SG AVB011=:41 LE"ND T I 0:" 0 : AVB 10%J. L-L L 0: AVS 2G%f I :AVS 21 -3D%T 7 T F AVS 31 -40%S;AVB > 41%4 4-4 I I L L J-L I L-'7 1 7 -T i7- r -i-, 71 '1 -r 1 4 J- j ir T, IT ý7 ý7 4 4;J sjýFig 4.1.1-5 (1/4) Tubes with wear indication (at AVBs)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 28 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I j (P.29)Document No.1-5-04GA564(9)

Ak.IA-4;f- A/R641 T r I I L LEEN 0:0%L L :V ~1 10'IA--';(, AV/RnOriI VI V W W W V VE 3A-SGAVB06_

LEGEND*:AVO3I41%

I IT 7 Fig 4.1.1 -5 (2/4) Tubes with wear indication (at AVBs)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 29 of 474 S023-617-1-M1538, REV. 0 f I I Non-proprietary Version I ( ) (P.30)Document No L5-04GA564(9) x 3A-SG XYBO-8ýl -:1ý :1ý-- ý1': ý1: 'ý4 :1 -1_=g1- to ----LEGEND T 0: 0%ý'l I L A 10%::AVB 20%i L :AVB AVB 2: 30%7 T T A 3 jj- 0 -B 3 A. > 4.%2" IL- :AV8 > 41%41.ýl L L L I-T-7 7 'T T if 1XI AS(A\/Rn91

-ýL I L L L L. 1 J r-7:T L LEEN 4- 4 -0:0 L L L-:-:-J-I-:AV 1- 0 Fig 4.1.1-5 (3/4) Tubes with wear indication (at AVBs)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 30 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I ( ) (P.31)Document No L5-04GA564(9) x'IA-';(- AVR111 I I L L L J I -I -' -L 1 L I -r r 1 -i -r -4 4 j I L 4 -----------LEGEND 0: 0%L L L 'L V -10%::A 8ý1 AVB -20%L J- -j .2 :AVB 21 -30%*:AVB 31 -40%*:AVB > 41%7 '1 Fig 4.1.1-5 (4/4) Tubes with wear indication (at AVBs)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 31 of 474 S023-617-1-M1538, REV. 0 I Non-nronrietarv Version I... .r -r ... ..i ... ... i (P .3 2 )Document No L5-04GA564(9) 3A-SG #1 TSP.44 4..J .4. .4 ..J ,.4 .4 J .4 .4 ..4 .J 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0- -" " -o 00 U 0 U U U 0 U 0 0 y 9 y 0 0 0 00000ý4d' 4 & 4 d, 4 &~ 4 6 9 A9 9 9 9ý2 t2ý2 : 0 0 0 0 0 0 00000y 0 0 0 0 0 0 0 .-ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141*.ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 O@¢ O 0 w ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 ROW-21 0 0 ff 4-4.-C ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141.4.4 .4. .4 .4 .4 .4 .J -.4. -._ .4 .4 .4.-J 000 0 090 0 0 0 0 0 0 0 00 A U64 Fig 4.1.1-6 (1/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 32 of 474 S023-617-1-M1538, REV. 0 INon-proprietary Version )Document No.L5-04GA564(9)

At 3SG #2TSP.44. .J _J4 .J .4 .J .4 .4 4 .00 0 0 0 0 0 0 0 0 0 0 00 L 0 0 00000000 0 r-V !2 t2 C2 V 7 V2 C C 0 0 O0 0 0 0 0 0 0 -d ' 9999999999 0 0 0 0 0 0 0 0 9 y q Q Q 9 9 y 0 00.z 0 A ' A C '! 0 00 ROW-141 ROW-131 ROW-121 ROW-111 ROW-91i ROW-81/ROW-71 ROW-61/ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-1 (V N'". lt ROW-141 ROW-1 31 ROW-121 ROW-111 ROW-101 ROW-9i ROW-81 ROW-71 ROW-61 N ROW-51 ROW-41 ROW-31 ROW-21 9 ROW-I ROW-l1 ROW-21 ROW-31 I ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 , ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 0000 0 0 0 00 0 0 0 8 0 ROW-1 K ROW-i ROW-11 ROW-21 o 0 IROW-41 ROW-51 ROW-61 o -/ ROW-71/" ROW-81 ROW-Si ROW-101 ROW-111 IROW-121>40-I 0 0 0 0 0 0 0 0 0 q5 y5 y yyq 0 05 05 C, C) 05 0 05 0 0 0 £5 0 V~~~~ C V C V C V y y y> 9 9 99999 9 9 0 00 V N N N N~~~~~~~~

0C6 V C 6-C C2 C2 C N N C y C N N N .ROW-131 ROW-141 Fig 4.1.1-6 (2/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 33 of 474 S023-617-1-M1538, REV. 0 INon-proprietary Version j P.4 Document No L5-04GA564(9) 3A-SG #3TSP 00 L.J_0~ 0L 3 0 ~ c 0co 0 000000 0 y y Q yy, 2Q 9 x y9 90 0 0 0 03 0 0 0 0 0 0 0 0 0 0 Q L) 0 0 ) 0 00 6 v A 4 y 9 ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 /ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 ROW-141 ROW-131 ROW-121 ROW-Ill ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 El V timliw 0 4 0 4 ROW-21 ROW-11 ROW-1 ROW-11 ROW-21 I ROW-41 ROW-S1 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 00 0 0 0 0 0 0 0 0 0 0 0 0 0~- ~- ~- ~- ~- ~- ~- ~- ~-04§ 6 oo 9 o 0 0 0 O 0 0 0 0 0 0 Fig 4.1.1-6 (3/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 34 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I ( ) (P.35)Document No.L5-04GA564(9)

Ar 3A-SG #4TSP 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ~- ~- ~- ~-09 y y y 9 9 y y 9 y y y y 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 oo 0'o ~ ,-~,40 90o o o o o o o, o o o o o 00 Y d, Y U y y L 0, v, -h4 4 .v d, d, Y YY 4 4 9 ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-1 N N I//(ROW-141 ROW-1 31 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71\ ROW-61 ROYW-51 ROW-41\ROW-31 ROW-21 ROW-11 ROW-1______I _____ROW-1 4 ROW-11 ROW-21 ROW-31 4 4 ROW-41 ROW-S1 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 N ROW-141 1 _______ -____1 ROW-1 ROW-11 ROW-21 0 ROW-41 ROW-Si ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 00 0 0 0 0 9 9 y y 00 00 0 00 00 0 9999090099y3y 0 0 0 0 0 00 0 0 0 0 0 0ý -..000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 44 4 4444 44 4 M4 6 4400 Fig 4.1.1-6 (4/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 35 of 474 S023-617-1-M1538, REV. 0 INon-proprietary Version ) R6 Document No L5-04GA564(9) 3-S:G #5TSP 00 O0 0'0 0 0 0 0 00 0 0 0 0 UJ0 0 0 0 0L) 0 0 0 00 00 000 9999999 00 0 0 0 0 0 0 0- --9 y 9 0 Q 9 9 9 9 0 00 4 4 h 4 04-T, 44 '4N ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 /ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 O¸I____________________________

_____________________

I 0~Li*ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 ROW-21 O O 0 IROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-1 31 ROW-141.-. -4. 4. .J --4-4 4 .J 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0-------------

00 0U 9 y 9 U 0 0 0 0 0 0 0 0"~~~ ~ ~ 00000- 9 y9y 0 0 0 0 0 0 0 0 0 0 0 0 ---O9 9 9 9 9 9 Q Q Q Q Q 0 00 CC t t t C Ct C C ýC C 0 0 to C~~tttrt CON N -dS 4-Fig 4.1.1-6 (5/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 36 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version 1] (P.37)Document No.L5-04GA564(9) 3A-SG #6TSP 00 0 0 0 0 0 0 0 0 0 0 0 0 0 Q 9 q0 0 0 9 Q Q 9 y 0 0 q0 0 00 0 0 0 0 00 0 00 0 0 0 0 0 0 -~-y0 y0 y 0 y 0 y y0 y 0 y y 0 000000000 0 o 000 R00 NN N 6 4 A4 4 6 6 4 4 64 v4 4 o 9 ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-i 3 ROW-1 ROW-li ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141////i 7K_,ZJ ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61\ ROW-si ROW-41\ROW-31 ROW-21 ROW-11 ROW-1 R ROW-1 ROW-11 ROW-21!ROW-31 ROW-41/ ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141'ii./00 0 0 0 0 0 0 0 0 0 0 0, 9p 9 0 0 0 0 0 0 0 0 0 0 0 y 0 0 0 0 0 0 0 0 0 0 0 0 0 0(J 0L) ) 8J 8 8 J0{L? y, y y Y" L? 4 y y, y y " 0 0 0 " 0 y 0 0 00-.000 YY Fig 4.1.1-6 (6/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 37 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I ( ) (P.38)Document No.L5-04GA564(9)

AO 3A-SG #7TSP 00ýU00 ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-1 31 ROW-141 (4 (D ,-4 _. -4 _4 .4 .4 4J ... _4 .j .0 0 0 0 0 0 0 0 0 0 0 0 64 4 4 4, d9 4 h 9 d t2t" t/ 41%1 4 I 7 tt lrl-i-i-ýýk L-h 0 9 Fig 4.1.1-7 (2/4) Tubes with wear indication (at AVBs)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 40 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I ( )] (P.41)Document No L5-04GA564(9) x 3BR-S';G AV B71 o"l I I 'I I L L L L I-T 7 T-i -T -r -r -r r r 7 .......A L 1. -------7 F T -r -T 3B-SG AVB8 7:, :: LEGEND 0:0%, 1, J :AVB I D%10 j J :AVB t1 20%:AVB 21 30%-- -- -- -:AV 31 40" 7- 7 L -----3B-SG AVB91--- LEGEND-0%: -*:AVB I 10%-:AVB1 20%:AVB 21 -30%-*:AVB 31 -40%*:AVB >41%-"- - 1 I~ I Fig 4.1.1-7 (3/4) Tubes with wear indication (at AVBs)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 41 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I (A ). (P.42)Document No L5-04GA564(9) 3B-SG AVB104 3-GAVR111 13RSflAV/R1 21 Fig 4.1.1-7 (4/4) Tubes with wear indication (at AVBs)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 42 of 474 S023-617-1-M1538, REV. 0 I Non-DroDrietarv Version I] (P.43)Document No L5-04GA564(9) x 3B-SG #1TSP 00000 0 0 0 0 0 0 0 0 C) -~ -~ ~- ~-99999999 Y 9 0 0 U 0 0 0 0 0 0 0 0 0 0 0 0 NO~~ ~ 0 Y 0 O u0Q~00000 000 0 0 0 0 0 0 000

....--. ROW-141 ROW-131 -. ROW-131 ROW-121 ROW-121 ROW-111 " ROW-111 ROW-101 / ROW-101 ROW-91 // ROW-91 ROW-81 / ROW-81 ROW-71 ROW-7i ROW-61 ROW-61 ROW-51 / ROW-51 ROW-41 RW4 3ROW-41 ROW-31 / ROW-31 ROW-21 ROW-21 ROW-11 ROW-11 ROW-1 0 0 0 ROW-i ROW-1 ROW-1 ROW-li ROW-11 ROW-21 ROW-21 ROW-31 0 0 ROW-31 ROW-41 / ROW-41 ROW-si \ / ROW-51 ROW-61 -/ ROW-61 ROW-7i 1 ROW-71 ROW-1 ' ROW-81 ROW-91 ROW-9i ROW-101 ROW-101 ROW-111 ",jROW-111 ROW-121 ROW-121 ROW-131 ROW-131 ROW-141 .. ---- ROW-141 00 0 0 0 0 0 0 0 0 0 0 0 0 00 99 99 9 y y 9 9 y 9 9 y y 99 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 Ny y y y y y0 y , y 0000000000000 0 00 So , ~...., -t o, o 0 o o , M 4 o o o o o o o y.49 .-Fig 4.1.1-8 (1/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 43 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version 1 )( .4 Document No L5-04GA564 (9)3-:SG #2TSP 00 oo ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 ROW-21 RCOW-11 ROW-1 ROW-1 ROW-11 ROW-21 ROW-31 ROW-4i1 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 00 9.9..0 y 0 0 y 0U00U00U 009990 0 0 00000 Y0 ~ 9 Ui Y9 q 9Y 000 0 0 0 0 0 0 0 0 -9 9 9 9 y 9 9 y 9 9 0 00 00 0 00 0 00M 0 g 0' ! 0-?/A.0~...__iL ROW-141ROW-121ROW-11101 ROW-91 RCY ROW-71 ROW-61 ROW-51 ROW-31 ROW-21 ROW-11 ROW-1 ROW-9 ROW-11 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 C/ ROW-91/ ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 0 0 0 0 0 0 0 RO -i'C YYL)L~y U QROyW0 0/ yOW-9 0 00 0 0 00 00, 0o UUUU 04 CO CO .4 C. 4- o t o 00 yy y 0 U 000 UUU Fig 4.1.1-8 (2/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 44 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I] (P.45)Document No.L5-04GA564(9)

Ak 3B-SG #3TSP 000 0 000 00 0 00 00 0 4.yC CO C 4 CC 00 0C 0C 00 O 09 0 0 0 0 90 9 09 C0 0 0 0 0 8N yOO O N fN .CO q~ Oy q~ y~ CC y 0C y 0 y Y 000O ROW-141 ROW-1 31 ROW-121 ROW-111 ROW-101 ROW-91 ROW-B1 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 F-I I ---ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61\ ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-1 ROW-i1 ROW-11 ROW-21 I ROW-31/ ROW-41/ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 ROW-21 ROW-31 ROW-41 \ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 C //4 /C./00 00 L 0 0 0 0 0 0 0 0.4 4 .2 .4. .4 Z4 A4..

.........000000000000000000000000)

' ( a o'J ' e 0 0 0 0*00 Fig 4.1.1-8 (3/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 45 of 474 S023-617-1-M1538, REV. 0 I Non-DroDrietarv Version I.... j (R.46)Document No L5-04GA564(9) 3B-SG #4TSP 00 0 0 0 0 0 0 00 0 0 0 0 y 9- ----, 0 0 0 0o 0 -00 000:2t- :2 to tot t: :: 1O 6 ý m -m t I U y0 ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-6i ROW-S1 ROW-41 ROW-31 /ROW-21 ROW-li ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41\ROW-31 ROW-1 LIZ ~ Z1 0 111 wow ROW-il RaWV-11 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 o , C ROW-11*ROW-1 C ROW-1 ROW-11 ROW-21 ROW-31 ROW-41 ROW-S1 ROW-61 ROW-71 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0aaaaaaaaaaaaaaaaaa yy 0 0( 0 0 y 00 Q ? Q0000 ,-tv ch d, 4 O'C v 4mv 9Y9 999Q Q9 000_CJ J _J _ Co CO CO NJ NJ -J _J -J -Jo ~ t Co o C o----oo o oo o o o CI C C- C ICC Co C CO N Fig 4.1.1-8 (4/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 46 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version )( ) (P.47)Document No L5-04GA564(9) x 3B-SG #5TSP 00 0 0 0 0 0 0 0 0 0 0 0 0 00 --00 9 0 0 q9y 0 0 0 0 00 0 0 0 0 0 0 0 00 0000.0..00

..................

C 9g v ' Y Y NU C 944 Y 4 U tC fl C C'-yQy 0Q ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-5i ROW-41 ROW-31 ROW-21 ROW-11 ROW-1.j -:!ýr-:4V ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 Z/I ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 ROW-21 ROW-31 ROW-1 ROW-11 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 C//ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 N 00 00.0 0 0 0 00000000'O0'0-00 0 y yy 000 00000 0 0 0 0 0 0 0 0 0 0 0 0 0 000 0 0 0 0 00 00 Fig 4.1.1-8 (5/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 47 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I) (P.48)Document No L5-04GA564(9) x 3B!-:SG #6TSP 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0- -(9 99 y 0 9 9 y 0y y q y y y 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -Cz a, , Y~ Y 000 9 9009Y0 00 NN C C C C C 4. 9ý 99 ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 /ROW-21 ROW-11 ROW-141 ROW-1 31 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 a * *,¸0 a 0 ROW-ROW-1 Li LTh71 ROW-21 ROW-11 ROW-1 ROW-1 ROW-11 ROW-11 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 Q O O/ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 00 0 0 0 0 0 0 0 0 0 0 0 0' 0 0 -~- ~- ~- ~-0000000 0 0 99 U 0 Q oO 000 0 00 00 0 000 00 0 00 0 0% 4 6 4 64 CC4 ,Y 9 y9 9 y9 99999Q99q9Q0 00 t2 CC CC C t2 1 0 C V CC2 1 CT C XC Cn 6-----C~~~~~~~~~~

C C ' 'Fig 4.1.1-8 (6/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 48 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I j (P.49)Document No.L5-04GA564(9)

AO 3B-SG #7TSP 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0- *'90 y Y 9 Y 0 0 U 0 0 0 0E 00 0 0 0 0 0 0 0 0 0 0 0 dd--7 O I O O O yy flt yN y y Ny -0 00o ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 /ROW-71 ROW-61 //ROW-51 /ROW-41 ROW-31 ROW-21 x 0I#0%ROW-141 ROW-131 ROW-121 ROW-111 ROW-101 ROW-91 ROW-81 ROW-71 ROW-61 ROW-51 ROW-41 ROW-31 ROW-21 ROW-11 ROW-11 ROW-1 ROW-1 ROW-11 L---J RC 1W-1 ROW-21 ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141@ROW-1 ROW-11 ROW-21/ ROW-31 ROW-41 ROW-51 ROW-61 ROW-71 ROW-81 ROW-91 ROW-101 ROW-111 ROW-121 ROW-131 ROW-141 00 0 0 0 0 00 0 0 0 0 0 0 00 0000y 0 0 0 0 0 0 -o oo499 oo- oo00 o00 u 0N 00 0 0 0 8 0 4- 0 0 -0 0 0 0 ---00000 00,.y y.y Fig 4.1.1-8 (7/7) Tubes with wear indications at TSPs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 49 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version )II ) (P.50)Document No.L5-04GA564(9)

Ak 4.1.2. Tube Wear in Unit-2 (for reference only)The tubes in Unit 2 have experienced wear at 4 locations, i.e. wear in the free span area, wear at the AVB bars, wear at the TSPs and wear at retainer bars, as well as wear due to a foreign object. Table 4.1.2-1 shows the number of tubes that have shown wear at these four different locations as well as foreign object wear and is provided by SCE (Reference 9 and 11).Table 4.1.2-1 Number of Tubes with Wear in SONGS Unit-2 SG 2A SG 2B Wear Type Total (2E-089) (2E-088)Tube-to-Tube 2 0 2*Wear AVB Wear 804 595 1399*TSP Wear 119 180 299*Retainer Bar Wear 4 2 6*Foreign Object 0 2 2*Total 861* 734** 1595"*Notes:*) The total number of tubes with wear at a given location**) The total number of tubes with wear at any location For purposes of analysis in this report, MHI has categorized the tube wear into the four types of wear as defined in Section 4.1.1 (Types of Tube Wear). Table 4.1.2-2 shows the number of tubes in the Unit 2 RSGs that fall into each of these types of wear.Table 4.1.2-2 Number of Tubes with Type of Wear in SONGS Unit-2 SG 2A SG 2B Wear Type Total (2E-089) (2E-088)Type 1 (TTW) 2 0 2 Type 2 (AVB wear) 802 595 1397 Type 3 (TSP wear) 53 137 190 Type 4 (RB wear) 4 2 6 Foreign Object 0 2 2 Total 861 736 1597 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 50 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I) (P.51)Document No,L5-04GA564(9)

All In this table each of the tubes is only counted once with priority given to Type I followed by Type 2, Type-3, Type 4 and Foreign Object. The data in this table is based on the ECT data evaluations described in Appendix-3 of Reference 8 which includes both bobbin ECT and rotated ECT data. The total number of tubes differs from that in table 4.1.2-1 because, as explained in Appendix 3, Reference 8, the data in Table 4.1.2-1 for wear at AVBs and TSPs is based solely on bobbin ECT data.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 51 of 474 S023-617-1-M1538, RE\(.0 Non-proprietary Version I) (P.52)Document No.L5-04GA564(9)

Ak 4.1.3. Tube Wear in Unit-3 The number of tubes for each type of tube wear in Unit-3 is listed in Table.4.1.3-1.

The tubes in Unit 3 have experienced wear at 4 locations, i.e. wear in the free span area, wear at the AVB bars, wear at the TSPs and wear at retainer bars. Table 4.1.3-1 shows the number of tubes that have shown wear at these four different locations and is provided by SCE (Reference 9 and 11).Table.4.1.3-1 Numbers of Tubes with Wear in SONGS Unit-3 SG 3A SG 3B Wear Type Total (3E-089) (3E-088)Tube-to-Tube 165 161 326*Wear AVB Wear 871 896 1767*TSP Wear 214 250 464*Retainer Bar Wear 1 3 4*Total 887** 919** 1806**Notes:*) The total number of tubes with wear at a given location**) The total number of tubes with wear at any location For purposes of analysis in this report, MHI has categorized the tube wear into the four types of wear as defined in Section 4.1.1 (Types of Tube Wear). Table 4.1.3-2 shows the number of tubes in the Unit 3 RSGs that fall into each of these types of wear.Table 4.1.3-2 Number of Tubes with Type of Wear in SONGS Unit-3 SG 3A SG3B Wear Type Total (3E-089) (3E-088)Type 1 (TTW) 165 161 326 Type 2 (AVB wear) 714 737 1451 Type 3 (TSP wear) 15 20 35 Type 4 (RB wear) 1 3 4 Total 895 921 1816 In this table each of the tubes is only counted once with priority given to Type 1 Type 2, Type-3, and Type 4. This data in this table is based on the ECT data MITSUBISHI HEAVY INDUSTRIES, LTD.Page 52 of 474 S023-617-1-f followed by evaluations M1538, RE\f. 0 Non-proprietary Version I] (P.53)Document No.L5-04GA564(9)

At described in Appendix-3 of Reference 8 which includes both bobbin ECT and rotated ECT data. The total number of tubes differs from that in Table 4.1.3-1 because as explained in Appendix 3, Reference 8 the data in Table 4.1.3-1 for wear at AVBs and TSPs is based solely A on bobbin ECT data.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 53 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I) (P.54)Document No.L5-04GA564(9)

4.2 Visual

Inspection Results of the Tube Bundle Based on the visual inspection performed along AVBs No.B04 and B09, the following observations were made (see to Appendix-7 for details).4.2.1. Observations Common to Unit-2 and Unit-3 The AVBs, end caps, and retainer bars were manufactured according to the design. It was confirmed that there were no significant gaps between the AVBs and tubes which might have contributed to excessive tube vibration because the AVBs appear to be virtually in contact with tubes as shown in Fig.4.2-1, Fg.4.2-2 and Fig.4.2-3.

ECT wear indications are identified as the Type 1 and Type 2 wear.4.2.2. Observations in Unit-3 Pattern 1 wear indicating high amplitude in-plane motion of the tube, as shown in Fig 4.2-2, was seen on the tubes with Type 1 wear. Pattern 2 wear, as shown in Fig 4.2-3, was seen on the tubes with the Type2 wear.4.2.3. Observations in Unit-2 Pattern 2 wear seen in Unit-3 was also seen on the tubes with the Type 2 wear tubes.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 54 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version) (P.55)Document No L5-04GA564(9) x Sample from SG-2A Sample from SG-3B Fig.4.2-1 Condition of Tube Wear in SONGS Unit-2 and Unit-3 I Wear (Pattern 1) by Visual Inspection I SG-3A (TTW Location)'Tube-Free Span Wear Wear at AVB location Fig.4.2-2 Illustration of Tube Wear Pattern 1 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 55 of 474 S O23-617-1-M1538, REV. 0 Non-proprietary Version I) (P.56)Document No L5-04GA564(9) x Wear Location, Fig.4.2-3 Illustration of Tube Wear Pattern 2 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 56 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version ( (P.57)Document No.L5-04GA564(9)

Ak 5. Mechanistic Cause Analysis The cause of the first 3 types of tube wear (i.e. TTW, AVB wear, TSP wear) is excessive tube vibration.

Generally, the causes of tube excessive vibration are the thermal-hydraulic operating conditions of the SG secondary side and lack of sufficient in-plane tube support for the tubes (condition of the tube supports in terms of their effectiveness; active versus inactive tube supports).The cause of the Type 4 tube wear (RB wear) is vibration of the retainer bar itself which is described in Section 6.5.1 Thermal Hydraulic Condition in the Secondary Side In general, structures in a two-phase flow field have lower resistance to vibration when a void fraction (percentage of vapor volume in a saturated mixture) or steam quality (percentage of vapor mass in a saturated mixture) is high. The high void fraction (steam quality) results in the two-phase fluid having a low density, which in turn results in an increase of the flow velocity of the two-phase fluid, and in a low damping factor. The increase of the flow velocity (v) causes the increase of the hydrodynamic pressure (pv 2) which causes structures to vibrate in-the flow field. The hydrodynamic pressure is a measure of energy imparted on the structure by the flow field, and damping is a measure of how easily the structure can dissipate this energy. If the amount of energy imparted on the structure is higher than the amount of energy dissipated, the structure (in this case the tubes) will vibrate with progressively increasing amplitudes, which eventually may lead to the tubes becoming fluid-elastic unstable.

Also, the unstable tubes will excite the surrounding tubes via two-way coupling with the fluid. Therefore, it is more likely for the tubes to vibrate when the void fraction (steam quality) is high.Fig.5.1-1 shows the results of the three-dimensional thermal hydraulic analysis of SONGS Unit-2 and 3 SGs (see Reference 5 for detail). This analysis was performed recently using the ATHOS computer code developed by EPRI. As can be seen from the void fraction profile, the highest void fraction is estimated to beI I (and the steam quality isj I), which is high compared to the I jvoid fraction (when steam quality is less thanI I) for the other SGs designed by MHI based on ATHOS computer code. The higher than typical void fraction is a result of a very large and tightly packed tube bundle, particularly in the U-bend, with high heat flux in the hot leg side. Because this high void fraction is a potentially major cause of the tube FEI, and consequently unexpected tube wear (as it affects both the flow velocity and the damping factors), the correlation between the void fraction (steam quality) and the number of tubes with wear in a given void fraction region was investigated.

From this investigation, a strong correlation between the void fraction (steam quality) and the percentage of tubes with the Type 1 and Type.2 wear was identified (see Fig.5.1-2 and Fig.5.1-4).

The correlation MITSUBISHI HEAVY INDUSTRIES, LTD.Page 57 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I) (P.58)Document No.L5-04GA564(9)

A&between flow velocity and the number of tubes with wear was also investigated.

The results show that when the flow velocity is high, the percentage of tubes with wear increases, even though this correlation is not as strong as that between the void fraction (steam quality) and the percentage of tubes with wear (see Fig.5.1-3 and Fig.5.1-5).

Consequently, it is concluded that the thermal-hydraulic conditions in the SG secondary side, namely high void fraction (steam quality) and high flow velocity along with lack of sufficient in-plane tube support, are the main causes of the excessive tube vibration and unexpected wear in the SONGS Unit 2 and Unit 3 RSGs.MITSUBISHI HEAVY INDUSTRIES,, LTD.Page 58 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I) (P.59)Document No.L5-04GA564(9)

AW Fig.5.1 -1 Thermal Hydraulic Analysis for the Unit-2 and Unit-3 SGs MITSUBISHI HEAVY INDUSTRIES, LTD.Page 59 of 474 S023-617-1-M1538, RE V. 0 Non-proprietary Version I) (P.60)Document No.L5-04GA564(9)

Fig.5.1-2 Correlation between Type 1 Wear (TTW) and Void Fraction (Steam Quality)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 60 of 474 S023-617-1-M1538, REV. 0 I Non-oroorietarv Version I I i ) (P.61)Document No.L5-04GA564(9)

A&Fig.5.1-3 Correlation between Type 1 Wear (TTW) and Flow Velocity MITSUBISHI HEAVY INDUSTRIES, LTD.Page 61 of 474 S023-617-1-M1538, RE V. 0 I Non-Dronrietarv Version I ( J) (P.62)Document No.L5-04GA564(9)

A Fig.5.1-4 Correlation between Type 2 Wear (AVB wear) and Void Fraction (Steam Quality)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 62 of 474 S023-617-1-M1538, REV. 0 I Non-Drorietarv Version I ( ) (P.63)Document No.L5-04GA564(9)

Fig.5.1-5 Correlation between Type 2 Wear (AVB Wear) and Flow Velocity MITSUBISHI HEAVY INDUSTRIES, LTD.Page 63 of 474 S023-617-1-M1538, RE V. 0 Non-proprietary Version I ( ) (P.64)Document No.L5-04GA564(9)

5.2 Evaluation

of U-bend Supports Condition 5.2.1. Out-of-Plane Direction Support The SONGS SG tube bundles were designed for out-of-plane U-bend support only with "zero" gaps in the hot condition.

Based on visual inspections, the tube-to-AVB gaps in cold condition were as could be expected, i.e., most likely meeting the design premise of "zero gap" in the hot condition.

The recent tube bundle deformation analysis (refer to Appenidx-8), which takes into account the tube and AVB dimensional fabrication tolerance dispersion, indicates that the contact forces between the tubes and AVBs produce the friction forces which prevent the distortion of the AVBstructure assembly and the dynamic pressure during operation does not increase the tube-to-AVB gaps (see Fig.5.7-3 and Fig.5.7-4f Appendix-8 for details).Therefore, MHI has concluded that U-bend support in the out-of-plane direction is adequate.5.2.2. In-Plane Direction Support By design, U-bend support in the in-plane direction was not provided for the SONGS SGs. In the design stage, MHI considered that the tube U-bend support in the out-of-plane direction designed for "zero" tube-to-AVB gap in hot condition was sufficient to prevent the tube from becoming fluid-elastic unstable during operation based on the MHI experiences and contemporary practice as described in Section 2.2.Secondary side thermal-hydraulic conditions in the SONGS SGs during operation appear to be such that the effective fluid flow velocities are higher than the critical velocities in the U-bend in-plane direction for several tubes in a particular region of the tube bundle where the void fraction is very high as described in Section 5.1.MHI concludes that under the secondary thermal-hydraulic conditions such as in the SONGS SGs, certain tube-to-AVB minimum contact force is required to prevent tubes from vibrating in the in-plane direction and eventually becoming fluid-elastic unstable.

Furthermore, MHI concludes that the tube and AVB fabrication dimensional tolerance dispersion results in contact forces between the tubes and AVBs, however, these forces are not sufficient to provide friction forces ample to prevent in-plane motion of the tubes (See reference 10 for details).MITSUBISHI HEAVY INDUSTRIES, LTD.Page 64 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version ( ) (P.65)Document No.L5-04GA564(9)

5.2.3. Differences

between Unit-2 and Unit-3 According to the manufacturing dimensional tolerance analysis (refer to Appendix-4 and Appendix-9 for details), the average contact force in the Unit-3 SGs was found to be smaller than the average contact force in the Unit-2 SGs. Consequently, the contact forces caused by /9 the manufacturing dimensional variations in the Unit-2 SGs are more than two times larger than in the Unit-3 SGs, which is consistent with the tolerance analysis results shown in Fig.5.2.1.Therefore, it is concluded that the contact forces of Unit-3 were more likely to be insufficient to prevent the in-plane motion of tubes and the Unit-3 SGs were more susceptible to in-plane tube vibration.

The difference in the contact forces between the Unit-2 and Unit-3 SGs was caused by the manufacturing dimensional tolerance variations, mainly due to improvement of AVB dimensional control. For the Unit-3 AVBs, al ]pressing force was used for the AVB nose portion after bending in order to control the twist and flatness of the AVB more precisely, while I I pressing force was used for the Unit-2 AVBs.. Because the manufacturing dimensional variations of the Unit-2 SGs are larger than those of the Unit-3 SGs (AVB twist at I^AVB nose portion of Unit-2 is larger than that of Unit-3), the tube-to-AVB contact forces of the Unit-2 SGs are greater than those.in the Unit-3 SGs, especially at the AVB nose locations, which is evidenced by more ding signals in the Unit-2 SGs than in the Unit-3 SGs.A comparison of the Unit-2 and Unit-3 materials, fabrication processes and inspections that might have had an impact on the condition of the U-bend supports is summarized in Table 5.2-1 (refer to Appendix-4 for details) and the evaluations for the factors other than the difference in the AVB pressing forces are summarized below.(i) Number of Rotations due to Divider Plate Repair The Unit-3 SGs underwentl I more rotations than the Unit-2 SGs due to the divider plate repair. However, the change in the tube support condition between the Unit-3 and Unit-2 SGs due to the difference in number of rotations was found to be negligibly small (refer to Appendix-5 for details).(ii) Number of Hydrostatic Tests Primary side hydrostatic tests were performed three times for the 3A SG and two times for the 3B SG, compared to only one time for both 2A and 2B SGs. However, the change in the tube support condition between the Unit-3 and Unit-2 SGs due to the number of hydrostatic tests was found to be negligibly small (refer to Appendix-5 and 14 for details).MITSUBISHI HEAVY INDUSTRIES, LTD.Page 65 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I ( 3 (P.66)Document No.L5-04GA564(9)

Ar (iii) Dimensional Control of Tubes and AVBs The standard deviation of the AVB thickness, the tube outer diameter (G-value), and the number of adjustments to the tube bending radius was smaller in the Unit-3 SGs than in the Unit-2 SGs. Furthermore, the gaps between the outermost tubes and the AVBs are more uniform in the Unit-3 SGs than in the Unit-2 SGs. These findings indicate that the tube and AVB dimensions of the Unit-3 SGs are more uniform, and hence the reaction forces from tubes and AVBs are smaller than the Unit-2 SGs. Consequently, the contact forces caused by the manufacturing dimensional variations in the Unit-3 SGs are smaller than in the Unit-2 SGs, which is consistent with the tolerance analysis results shown in Fig:5.2-1.

The average of all gaps between the tubes in the outermost rows and AVBs along the retaining bars is smaller in the Unit-3 SGs than in the Unit-2 SGs. However, the gaps between the outer-most tubes and AVBs in the center columns do not have significant effect on the contact forces in the inside of the tube bundle and the main reason for this difference is the fact that the gaps in the outer-most rows of the peripheral columns in the Unit-2 SGs were larger than those in the Unit-3 SGs. The average of the gaps between the outermost tubes and AVBs in the center 60 columns (Column 59 to 119), where the wear indications were found, were essentially the same in the Unit-2 and Unit-3 SGs as shown in Fig.5.2-2.

Therefore, the difference of the contact forces between Unit-2 and Unit-3 is caused by the difference of the manufacturing dimensional tolerances other than the outer-most tube-to-AVB gaps.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 66 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version )( ) (P.67)Document No.L5-04GA564(9)

AW 0 Tube G-value Manufacturing Tolerances)AVB th ickness U AVB twist AVB Flatness Tube Flatness Tube pitch (True position of land)Contact forces of Unit-2 are more than 2 times larger than those of Unit-3.Fig.5.2-1 Contact Force Simulation with Manufacturing Tolerances MITSUBISHI HEAVY INDUSTRIES, LTD.Page 67 of 474 S023-617-1-MI 1538, REV. 0 I Non-proprietary Version I ( (P.68)Document No.L5-04GA564(9)

Ak Table 5.2-1 Manufacturing Differences Between Unit-2 and Unit-3 SGs Item Unit-2 Unit-3 Reason / Effect Rotations Due to divider plate repair Due to seal-weld leakage Hydrostatic Test and divider plate repair AVB twist and flatness of AVB pressing force Unit-3 SGs are controlled more precisely Standard Deviation of Tube Outer Diameter Unit-3 has smaller standard (G-value"&)

deviation mils (mm)Unit-3 had fewer Adjustment of Tube Bdjumendg Rduse adjustments of tube bending Bending Radiusrai radii Unit-3 has smaller gaps.Average Gap Most of the difference is in between Outermost the peripheral columns not Tube and AVB*2 the central columns (where mils (mm) the wear indications are I_ I_ -_ found).Note)*1: G-values were measured by micrometer.

2: Outermost peripheral gaps near the retaining bar-to-AVB welds were measured by feeler gages.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 68 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I) (P.69)Document No.L5-04GA564(9)

Fig.5.2-2 Comparison of the outer-most tube-to-AVB gaps in the center 60 columns MITSUBISHI HEAVY INDUSTRIES, LTD.Page 69 of 474 S023-617-1-M1538, RE V. 0

version) (P.70)Document No.L5-04GA564(9)

6. Tube Wear Causes In general, there are 3 types of tube bundle vibration phenomena occurring in fluid environment (see Fig.6-1): (1) Vortex Shedding Vibration (vibration due to Karman vortex)In a single-phase flow when fluid is flowing perpendicularly to a tube, a pair of vortices, known as Karman vortices, will form periodically on the right and left side, and downstream of the tube. When the vortices move away from the tube surface periodically, the reaction forces created by them will cause the tube to vibrate. This phenomenon is called vortex shedding vibration.

The fluid flow across the SG tubes in the region of interest (U-bend region) is a two-phase flow with high void fraction (>I 1). Therefore, no Karman vortices are expected to form periodically downstream of the tube and no vortex shedding induced tube vibration is expected to occur. Empirical data confirms that vortex shedding vibration typically does not occur in two-phase flow environments where the void fraction is greater than 15%(see Reference 1).(2) Random Vibration Random vibration is a phenomenon where the tubes vibrate due to forces created by turbulent flow as a result of fluid velocity and density fluctuations.

Vibration amplitudes due to random vibration are generally small (smaller than those due to tube fluid-elastic instability).

(3) Fluid Elastic Instability (FEI)FEI is a phenomenon where the tubes vibrate with increasingly larger amplitudes due to the fluid effective flow velocity exceeding its specific limit (critical velocity) for a given tube and its supporting conditions and a given thermal hydraulic environment.

This occurs when the amount of energy imparted on the tube by the fluid is greater than the amount of energy that the tube can dissipate back to the fluid and to the supports.In the case when vibration occurs in a two-phase flow such as in the SG tube U-bend region, there is a possibility that it is either due to random vibration or FEI. Based upon the abovementioned study of vibration phenomena, the mechanism of each tube wear type is evaluated next based on the fault tree evaluations shown in Fig.6-2 and Fig.6-3.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 70 of 474 S023-617-1-M1538, REV. 0 I Non-provrietarv Version I ( ,) (P.71)Document No.L5-04GA564(9) 6.1 Type 1 Wear (TTW)Based on the results from the rotating pancake coil ECT inspections and visual inspections, MHI concluded that the Type 1 wear (TTW) occurred due to tube in-plane motion (vibration) with a displacement (amplitude) greater than the distance between the tubes in the adjacent rows, resulting in tube-to-tube contact. Tube in-plane motion might have been caused by tube random vibration or FEI. Because the amplitude of random vibration is generally very small, the mechanistic cause of this type of wear is typically tube FEI (refer to Fig.6-1 for the difference between random vibration and FEI).U-tube out-of-plane direction is more susceptible to flow-induced excitation than the in-plane direction due to lower U-bend natural frequency in the out-of-plane direction.

U-tube FEI in the in-plane direction has never been observed in the U-tube SGs before its occurrence in the SONGS SGs. However, recent academic studies (Reference 2 and 3) report that FEI may also occur in the in-plane direction, if tube motion in the in-plane direction is possible (no tube in-plane supports or low tube contact forces with the out-of-plane supports, as concluded by MHI).As described in Section 5.1, the void fraction (steam quality) and the flow velocity are high in the SONGS SGs which means that their tubes are generally more susceptible to vibration.

Furthermore, the average tube-to-AVB contact force in the Unit-3 SGs is concluded to be smaller than in the Unit-2 SGs, as described in Section 5.2, which makes the Unit-3 tubes to be even more susceptible to vibration and likely to FEI. Therefore, MHI concludes that in-plane tube motion which caused the Type 1 wear was due to tube FEI. The wear at the AVBs and at TSPs on some of the tubes with the Type 1 wear is an additional effect of these tubes being unstable (refer to Fig.6.1-1).

6.2 Type 2 Wear (AVB wear)Based on the visual inspections, MHI concluded that the Type 2 wear occurred due to tube vibration which caused the tubes to wear against the AVBs at the tube-to-AVB intersections.

Tube wear at AVB intersections might have been caused by tube random vibration or FEI.However, because most likely there were no significant gaps between the tubes and AVBs during operation (see Section 5.2.1), the occurrence of tube motion due to FEI is very unlikely (refer to Appendix-3).

As described in Section 5.1, the SONGS SG tubes are susceptible to vibration (high void fractions and high flow velocities).

Therefore, MHI concludes that the tube MITSUBISHI HEAVY INDUSTRIES, LTD.Page 71 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I ( ) (P.72)Document NoL5-04GA564(9) wear at AVB intersections, which caused the Type 2 wear, was due to the random vibration (refer to Fig.6.2-1).

The Type 1. and Type 2 wear are simulated in the tube wear analysis as shown in Appendix-1 0.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 72 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version )] (P.7) " Document No.L5-04GA564(9)

A&6.3 Type 3 Wear (TSP wear)The tubes with the Type 3 wear are located mostly near the TSP flow slots and at the periphery of the tube bundle where the velocities of cross-flow are high (refer Fig.6.3-1).

Tube vibration in cross-flow may be caused by tube random vibration or FEI. However, the size of the gap between the TSP tube hole land surface and the tube is limited (design size is! 1). Thus, the occurrence of tube FEI is unlikely.

Therefore, MHI concludes that the Type 3 wear is caused by cross-flow induced random vibration in the region where secondary fluid cross-flow velocities are high (refer Fig.6.3-2).

The results of the FEI and random vibration analysis are shown in Appendix-2.

6.4 Type 4 Wear (RB wear)The tubes with the Type 4 wear have no indications of TTW or AVB wear, or TSP wear, which suggests that it is caused by only the retainer bars vibrating.

SONGS SGs have two types of retainer bars, I Imm (1 1) in diameter andl Imm (1 1) in diameter.

Tube wear was found on the tubes adjacent to the retainer bars, but only at the smaller diameter retainer bars.The retainer bars with the smaller diameter have also a relatively long span as compared with the other SGs fabricated by MHI, which means that the natural frequency of these retainer bars is lower and thus they are more likely to vibrate. Therefore, MHI concludes that the Type 4 wear is caused by random vibration of the retainer bars induced by the secondary fluid exiting the tube bundle(see Reference 4 for details).MITSUBISHI HEAVY INDUSTRIES, LTD.Page 73 of 474 S023-617-1-M1538, REV. 0 INon-proprietary Version j P.4 Document No.L5-04GA564(9)

Ak Downstream

> In a single-phase flow when fluid is flowing perpendicularly to a tube, a pair of vortices, known as Karman vortices, will form periodically on the right and left side, and downstream of the tube. When the vortices move away from the tube surface periodically, the reaction forces created by them will cause the tube to vibrate. This phenomenon is called vortex shedding vibration.

Karman Vortex Upstream Random vibration is a phenomenon where the tubes vibrate due to forces created by turbulent flow as a result of fluid velocity and density fluctuations.

Vibration amplitudes due to random vibration are generally small (smaller than those due to tube fluid-elastic instability).

Downstream Each tube vibrates G Independently

\J Fli V Force Upstream I I v'Fluid El astic Instability (FEI) I I>FEI is a phenomenon where the tubes vibrate with increasingly larger amplitudes due to the fluid effective flow velocity exceeding its specific limit 11 Fluid Elastic Instability Random Vibration A Tube vibration affects surrounding Downstream fluid and causes fluctuation which propagates to other us tubes n tustream C oupled Vibration due to tube motion" (ube motion affects surrounding fluidI Wen tube motion and fluid force lflctuate at the right time, tubes vibrateI flIv11gorously)

I,/Fig.6-1 Flow Induced Tube Bundle Vibration MITSUBISHI HEAVY INDUSTRIES, LTD.Page 74 of 474 S023-617-1-M1538, REV. 0 E Part Assumed cause Evaluation Concusion Wear of tubes for Unit-3, U-bend.region Tube-to-Tube Wear Fluid Elastic Instability Progress of wear in very short Yes I(FEI) .eiiod can be caused db FEI.Randm vbraion ibra-tion amplitudes due to radm No/vibration are genierally small and not -Random vibrationtubeoube w Karman vortex shedding Karman vortex shedding does not No[ocur in two-phase flow environments.

at AVB FEI Because most likely there were no No significant tube-to-AVB gaps'dudng operation, the occurrence of tube out-of-plane FEI is viery unlikely.Random vibration H SONGS SG tubes are susceptible to Yes random vibration due to high void U) fractionsand high flow velocities.

t-U M 4Karman vortex sheddinq (same as tube-to-furbe wear' ! No I (D M at retainer bar vibration of tube e ubes with retainer bar wear No-4 > -haveNo indications-0f TTW of AVR Lwear, or TSP wear, which suggests Zthat it is caused by only the retainer-_Z vibrating.

viraio of) reaiebr Retainer bars have a relatively smalll Yes X-4 ..Idiiifieter and long span as Yes rn; I corftpared with the other SGi_l fabricated by MHI, which means that _ _the natural frequency of these -r z retainer bars is lower and thus they 0____ _ -'lare more likelyto vibrate. 7______'_at Tube support plate (TSP) FEI The size of the gap between the No 0 TSP, tube hole land surface and the '--o tube is limited. Thus. the occurrence CD of tube FEI is unlikely. (D R vibration TSP wear can caused by the cross- Y <-4 flow induced random vibration in the region where secondary fluid cross- U .flow velocities are high. 0 01 Kam~an vortex sheddin (same as tube-to-tube wear) No)C.71~~~~~~(T

,._anvrtxsh,,7t~__-

Fig.6-2 Fault Tree Evaluation for the Causes of Wear V m FEI and Theomsl Irlncrease of polential of tube Higher void fraction t U-bend region T h drmal a) lyset SaruSuructs in awo-wfiase flow fiWl have lower resiae o Yes Random .ifydraHic LIv on vit retion when a void fraction or steanm quality is high II _______ _____R H Sesfctirn 5,1 for de"Itsl)L lcur AVB ~ ", tili [Ro n handigtc.

of RSGa durig on AVB iertin depth by bobbin I s i e that AVB inertion depth is not changed dtion manufcturing ECT signals fonm hti design condition for the representative colurns (S4. Section Apprnd-4 for diitel.)Contact foroe of AVO to Manufacturing dimensional disperaon Tube diameter ovskity (G vakie) Tubes uLed for Unt-2 havo larger variation (standard Ys tube devilton) of tube 0 value tihn those for Unit-3.It Isaessumed that the crtstd force of AIS to tubo for LUk-2 Ib relatively large compared with Urit-3.(See Section 52,3 and Apenpdx-, for details.)AVB tier end thickness AVB blia thickneee of Unit-2 we Igr then those o ye$Unk-3 because of tie diffsreio.

of AVB prsesing loed.(See Section 52.3 and Appendix-9 for details)('3[ ECT date (Ding signa1) The tube4o-AV1B contact forces of the Unit-2 SGe are yes SLgreater than those in the Unit-3 Ga, especially t tihe AVS not.e locations, which Is evidenced by more ding signals In the Unlt-2 SGs rtuan in the Unit-3 SOs,=r" l(See Section 5.2,3 aid A ilendxi- for detals.)>Rotation.

hancing. etc. of RSGs during Research of history end recorda of mwufacnuactng The Unit-3 SGs underwerl I[more then tie No ILbundle chdange In the tube support condtion bevieen Unit-3 z and Unit-2 SGs due to the difference In number of rotaions wes found to be negligitily malt gh tfee Section 5.2.3 and A4pe,.dix-5 for delalls.)Tubeto-A gap Rotation.

handg. atet. O RSGs uit, eserch of 4 iTtohy ant records of Smansufing

/ I l-3, undenwentl Imore rotation$

then the No manufacturing at Kobe shop aid deformation sanlysee of tube lUnt-2 SGs due to the divider plate repair. However, tie undl chane In the tube support condition between "h Unit-3" land Unit-2 SGs due to the difference in number of Z (SIee Section 5.2.3 and for detaIl) 7 Vll inspection of inside of U-band region The were no signifcant gape between tie AV" and No 0 hsbes whioh might have contilited to Uvessive tube 0 vjib on becatuse, tie W Ss appears to be Mrally in contect with tubel D Dacbmsiaoni of U-bend tDynanmio pressure of secondary flid Desformation analyses of tube bundlasby taking The tube bundle deformation analysis Indlcatsee that the No <region during operation and dfference of thermal expansion Into count of. -contact force between the tubes end AVBS pmrduce the CD> DFighc presure of secondary fuid rlM forcs which pevent i d on of the A)! II ] M Di thncoftermsl expansion Istrcture tie dynarili pressure I durIng operaion do"j not Iloibetive tH o-AW gaps. 6 o M Fig.6-3 Fault Tree Evaluation for the Causes of FEI and Random Vibration

,.cDo 0 INon-proprietary Version )Document No.L5-04GA564(9)

At[:::::Characteristics of SONGS RSG[Thermal Hydraulics]-I

/Design with High Steam Quality in U-Bend(maxl 1)[AVB Structure]

V Tube between 2 flat AVBs-AVB Design Assumes Out-of Plane Vibration Since out-of-plane FEI is more likely to happen compared to in-plane FEI. AV13s are placed at the sides of tube to preven Out-ot plane vibration v/ 6 V-Shaped AVBs (12support points)-Number of AVB Support Points are designed by FE!Evaluation based on ASME Sec.l11 (Out-of-Plane FEI Wil not occur even if one of supports is inactive as design basis)/Designed and fabricated for "Zero" Gap between Tube and AVB in hot condition Void Fraction Distribution in 100% Output Tubes Fig.6.1 -1 Type 1 Wear (TTW) Mechanism MITSUBISHI HEAVY INDUSTRIES, LTD.Page 77 of 474 S023-617-1-M1538, REV. 0 INon-proprietary Version ) R8 Document No L5-04GA564(9) x[Visu Inspection Results]=*Configurabon r Out-of-Plane Vibration is Confirmed Tube contacts AVB dueto Random Vibration[ Visualnpeto Results ]IRNo signifiant gaps between tubes and AVB.Low probability of Out-of-Plane FEI I Causes of Random Vibration I High Void Fracion Cauies High two Phase Flow Average Velocity In Vibraton Excitaton Force" High Void Fraction Causes Low Damping j Characteristics of SONGS RSG[Thermal Hydraulic]

[Structure]

I (Very Dry Steam Void Fraotin (Max 0.996 Steam Quality (Max.0.$)I I ZeoGap b3etween Tube*nAV8 in esig and I Manufacturing I f 2-hseFow Average V loctyInrease I I Vi1bration Resistance (Damiping Rato) Decrease I I Random Vibration Excitation Force Increase ,I Low contact force between Tuibe ndAV$ during Opraio Iccreneof Randm ibaj Fig.6.2-1 Type 2 Wear (AVB wear) Mechanism MITSUBISHI HEAVY INDUSTRIES, LTD.Page 78 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version) (P.79)Document No.L5-04GA564(9)

A&\jeu All Row.1 Tube S 4, 0'I 2*4, A-4, a C I Height from Tubesheet

[ft] Out-of- Axbe Plane Ax In-Plane 04, Ce Height from Tubesheet

[ft]Fig.6.3-1 Flow Velocity Distribution at TSPs (Actua Desgn]-Low probability of FEI due to support condition of Tube Straight Region (extremely email gap -between land region of BEC Hole and tube (Nornikial Gap: 0.31rmm))Main cause of Random Vibration L High Local Flow Velocity in the Horizontal Direction due to Tube Arrangement

!(Vibration Excitation Force Increase)I Characteristics of SONGS RSG I Tube contacts Land-Region of BEC Hole due to Random Vibration Narrow Pitch Tube Arrangement High Flow Velocities in Tube Straight Region Occurrence of Randomibrion Fig.6.3-2 Type 3 Wear (TSP wear) Mechanism MITSUBISHI HEAVY INDUSTRIES, LTD.Page 79 of 474 S023-617-1-M1538, REV. 0 0 tI-CL C C C.C-z 0 E C.-0 The tube which has wear at retainer bar region however does not have wear at AVB region (It is considered that Retainer Bar itself isVibrating)

It is cnlddthal Vibatonof Retainer Bai-SONGS RSGs have 2 types of retainer bars, which are retainer bars with small diameter and with large diameter.

However, wear indications are only found at contact regions between tubes and retainer bars with small diameter.I Cause of Random Vibration E.0 CU 7, a, C6 WJ Z-D)4-V Retainer Bar Design with Low Natural Frequency._

Retainer Bar '/;i efnto Is to hold AVI "anMbfr to the tub. bundle drnin *each stag. of instdton ad opacv SSONGS RSGa have retatna bars at 24 1Won~m 112 Locat~n. Each of Large Dtuseter#

010.. & Sinai Dkuatar R4.T e in)ng a Retaining Bar Non-proprietary Version I) (P.81)Document No.L5-04GA564(9)

AOk 7. Conclusions-In the Unit-3 SGs, the following types of wear were identified: (i) Type 1 (TTW)(ii) Type 2 (AVB wear)(iii) Type 3 (TSP wear)(iv) Type 4 (RB wear)The conclusions regarding mechanistic causes of tube wear are as follows:* The concluded mechanistic cause of the Type 1 wear is tube FEI in the tube bundle U-bend region, which is caused by a combination of the SG secondary side thermal-hydraulic conditions (high fluid velocity and high void fraction) and inactive AVB support conditions in the in-plane direction.

The concluded mechanistic cause of the Type 2 and 3 wear is random vibration of the tubes. The Type 2 wear is caused by the tube motion due to high void fractions and 9 high flow velocities.

The Type 3 wear is caused by high velocity flow across the straight leg sections of the tubes." The concluded mechanistic cause of the Type 4 wear type-is vibration of the retainer bar, which is the same as in the Unit-2 SGs and is addressed in Reference 4.The tube-to-AVB contact forces of Unit-3 were more likely to be insufficient to prevent the in-plane motion of tubes and the Unit-3 SGs were more susceptible to in-plane tube vibration than Unit-2 SGs because the average contact force in the Unit-3 SGs was found to be smaller than the average contact force in the Unit-2 SGs. The difference in the contact forces between the Unit-2 and Unit-3 SGs was caused by the manufacturing dimensional tolerance variations, mainly due to improvement of AVB dimensional control.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 81 of 474 S023-617-1-M1538, REV. 0 Non-prorietary Version ]( ) (P.82)Document No.L5-04GA564(9)

JAW 8. Countermeasures for Return to Service The following short term actions should be taken in support of Unit 3 return to service for a limited period of time (if possible)..In order to restore SONGS SGs' conformance to the CDS and make them capable of operating without time or reactor power level restrictions, more complex and involving actions (repairs) will be mandatory.

8.1 Tube Plugging Tubes which exhibit a potential for losing their integrity during the next operating period due to progressive through-wall wear and/or susceptibility to FEI should be plugged. The number of tubes plugged for each type of tube wear is listed in Table 8.1-1.8.1.1. Type 1 Wear All tubes with ECT tube wear indications in the free span section should be plugged regardless of the wear depth. Furthermore, tubes with wear indications at the AVB and TSP locations, which are similar to those on the tubes with the wear indication in the free span section, should be preventatively plugged.8.1.2. Type 2 Wear and Type 3 Wear Tubes with wear equal to, or greater than, 35% should be plugged in accordance with Technical Specifications.

8.1.3. Type 4 Wear Tubes with wear indications adjacent to the retainer bars should be plugged regardless of the wear depth. Furthermore, all tubes that have a possibility to come in contact with the retainer bars should be preventatively plugged.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 82 of 474 S023-617-1-M1538, RE\/.0 I Non-DroDrietarv Version I N ...s ] (P.83)Document No.L5-04GA564(9)

At NOTE: As of this writing, tube plugging has already been performed in the Unit-2 and Unit-3 SGs, and the number of the tubes for each plugging type is listed in Table 8.1-1 below.Table 8.1-1 Plugged Tubes Steam Generator Wear Type/Plugging Type Total 2E088 2E089 3E088 3E089 Type 1; Wear (with wear indication) 2 161 165 '328 Type 1 Wear (preventative plugging) 109 212 164 128 613 Type 2 Wear and Type 3 Wear 4 1 5 Type 4 Wear (with wear indication) 2 4 3 1 10 Type 4 Wear (preventative plugging) 92 90 91 93 366 Total 207 308 420 387 1322% Tubes Plugged 2.2% 3.2% 4.4% 4.0%MITSUBISHI HEAVY INDUSTRIES, LTD.Page 83 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I ( ) (P.84)Document No.L5-04GA564(9)

AO 8.2 Operating at a Lower Thermal Power As described in Section 6, the major contributor to the tube wear phenomenon in the SONGS SGs is the secondary side thermal-hydraulic conditions in the tube bundle U-bend region of interest at 100% reactor power. The major parameters making these conditions unfavorable from the tube wear perspective are high secondary fluid flow velocities and high void fractions (steam quality).In general, decreasing the reactor power level will result in the fluid flow velocities and void fractions being lower, and hence tube margins to FEI being larger. Lowering the plant reactor power level to 70% is sufficient to decrease the fluid flow velocities and void fractions in the tube bundle region where tube wear, especially TTW, occurred during the previous operating period to the point at which the tubes remaining in service are not expected to become fluid elastic unstable, as shown in Fig. 8.2-1 (Details of the secondary side thermal-hydraulic conditions are described in Reference 5).The effects of area plugging and power level reduction were investigated in the case study for their impact on tube stability (Reference 6). The results of this study indicate that the changes in the bundle thermal-hydraulic parameters reduce the stability ratios (increase margins to FEI) of the analyzed tubes slightly, but the ratios are still greater than 1.0 at 100% reactor power and the number of consecutive inactive AVB support points being 6 or more. Because no credit can be taken for a change in the tube support condition, as no modifications to the AVB support structure are possible in the short term, only reduction in power level can produce a beneficial reduction of the stability ratio (increase of margin to FEI) for the tubes remaining in service (not plugged).MITSUBISHI HEAVY INDUSTRIES, LTD.Page 84 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I ( ] (P.85)Document No.L5-04GA564(9)

Alk-.1 Fig.8.2-1 Void Fraction or Steam Quality Distribution of Thermal Power Reduction MITSUBISHI HEAVY INDUSTRIES, LTD.Page 85 of 474 S023-617-1-M1538 , REV. 0 Non-pro prietar Version J) (P.86)Document NoL5-04GA564(9)

9. References (1) Journal of Fluids and Structures, "Vibration analysis of shell-and-tube heat exchangers:

an overview -Part 1:flow, damping , fluid elastic instability", M.J. Pettigrew, C.E. Taylor., March 2003 (2) ASME, "Fluidelastic Instability and Work-Rate Measurements of Steam-Generator U-Tubes in Air-Water Cross-Flow", V.P.Janzen, E.G.Hagberg, M.J.Pettigrew, C.E.Taylor.

February 2005 (3) Flow-Induced Vibration,Meskell

& Bennett ISBN 978-0-9548583-4-6, "Study on In-flow Fluid-elastic Instability of Circular Cylinder Arrays"], T.Nakamura, Y.Fujita, T.Oyakawa, Y.NI. July 2012 (4) MHI report, "Retainer Bar Tube Wear Report", L5-04GA561 the latest revision (5) MHI report, "Case study of the input parameters and tube plugging impact on internal SG thermal hydraulic parameters", L5-04GA566 the latest revision (6) MHI report, "Evaluation of Stability Ratio for Return to Service", L5-04GA567 the latest revision (7) JSME, S016-2002, Guideline for Fluid-elastic Vibration Evaluation of U-bend Tube in SG, March 2002 (8) MHI report, "Screening Criteria for Susceptibility to In-Plane Tube Motion", L5-04GA571 the latest revision (9) SCE project letter, "L5-04GA564, REV. 6, TUBE WEAR OF UNIT-3 RSG TECHNICAL EVALUATION REPORT", RSG-SCE/MHI-12-5757, August 2012 (10) MHI report, "Analytical Evaluations for Operating Assessment", L5-04GA585 the latest revision (11) SCE project letter, "Updated ECT Data for Input to Return to Service and Repair Design IA Documents", RSG-SCE/MHI-1 2-5749, August 2012 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 86 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version I)(P.1-1)Document No.L5-04GA564(9)

At Appendix-1 ECT Data Evaluation of tubes with wear around Retainer Bar MITSUBISHI HEAVY INDUSTRIES, LTD.Page 87 of 474 S023-617-1-M1538, V. 0 Non-proprietary Version I](P.1-2)Document No.L5-04GA564(9)

A&1. Purpose This appendix provides the ECT data evaluation of tubes with wear around the retainer bars in the two Unit-3 SGs.2. Result Table 2-1 shows tube wear identified at the intersections with AVB assembly retainer bars for Unit-3.Table 2-1. Retainer Bar Tube Wear+Point Circ Axial SG Row Col Location Side depth extent extent 3B 117 137 B10 -0.42" Out 44% 0.47" 0.35" 3B 125 49 Bl -0.50" Out 28% 0.29" 0.27" 3B 128 126 B10 -0.44" Out 41% 0.44" 0.32" 3A 124 130 B11 -0.47" Out 46% 0.45" 0.27" Note: The retainer bar is captured between two tube rows in each column. "Out" describes the tube with the larger bend radius.Hot Leg-Top TSP-Cold Leg Top TSP Fig.2-1 Retaining Bar and Retainer Bar Locations MITSUBISHI HEAVY INDUSTRIES, LTD.Page 88 of 474 SO2 3-617-1-M1538, REV. 0 Non-proprietary Version)(P.1-3)Document No.L5-04GA564(9)

A&Figures 2-2 and 2-3 provide an overview of the indication locations.

Figure 2-4 shows a close-up view of the location with the deepest wear mark.For these four tubes, it is confirmed by bobbin ECT data that no indication is detected at AVB and TSP contact points except the intersections with retainer bars, as shown in Table 2-2.This shows that the tube wear was not caused by the vibration of the tube but by the vibration of the retainer bar.Table 2-2 Bobbin ECT results for tubes with retainer bar wear SG Row Column B01 B02 B03 B04 B05 B06 B07 B08 B09 B10 B11 B12 117 137 ---------W 3B 125 49 ----------W 128 126 ---------W -3A 124 1 130 ----------W BOB i 807 230580 804 808 803 B10 B02 III B01 812 07H 07C 08H 3 05H C 04H 03H 0 02: 02C 01 L1I TSHTI HOT COLD-: No wear W : Wear at retainer bar location 3. Reference 1. ECT Data for Input to Return to Service and Repair Design Documents (RSG-SCE/MHI-12-5688), e-mail from SCEs Mr. Calhoun on March 23, 2012 (JST)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 89 of 474 S023-617-1-M1538 , REV. 0 Non-proprietary Version])(P.1-4)Document No L5-04GA564(9) x Tube R125C49 Tube R117C137 JTube R128C126 Tube R124C130 Fig.2-2 Indication locations for Unit-3B Fig.2-3 Indication location for Unit-3A I'll iSL.A1I, DI"UE 4V:3'Fig.2-4 Location of 46% Wear (for Unit-3A, RI 24C1 30, AVB1 1 Retainer Bar)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 90 of 474 S023-617-1-M1,5 p38, REV. 0 I Non-proprietary VersionI (P.2-1)Document No.L5-04GA564(9)

Ak Appendix-2 FEI Evaluation of Tube Straight Portion for Unit-2/3 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 91 of 474 S023-617-1-M1538, RE V. 0 Non-proprietary Version I}(P.2-2)Document No.L5-04GA564(9)

Ak 1. Purpose Tube-to-tube support plate (TSP) wears at tube straight portions are detected in SONGS-2/3 RSGs. It is possible that the cause of the wears is the fluid elastic instability (FEI) mechanism.

The purpose of study provided in appendix-2 is to evaluate the possibility of FEI of the tube straight portion, through the thermal and hydraulic calculations by ATHOS/SGAP computer code and vibration calculations by FIVATS computer code (The evaluation of random excitation mechanism is provided in Appendix-2A).

2. Conclusion In order to evaluate the possibility of FEI in the tube straight region- the stability ratios defined in Section 6 for representative tubes are calculated with assuming TSPs effective supports because the gap between the tube and TSP is enough small. The analysis predicts that FEI of tube straight portions is not possible in case that all TSPs supports are effective.

Thus, MHI concludes that the cause of tube-to-TSP wears in SONGS-2/3 RSGs is not due to FEI in the straight portion of tube due to the cross flow.Table 2-1 Stability ratio calculations summary Tube address Stability ratioM.Conservative case(**) Best estimated case Row 1 Column 1 Hot side Hot side Row 1 Column 13 Hot side Hot side Row 1 Column 89 Hot side Hot side Row 53 Column 57 Hot side Hot side Row 80 Column 74 Cold side Hot side Row 101 Column 29 Hot side Hot side Row 137 Column 77 Cold side Hot side (*) Stability ratio over 1.0 implies a probability of FEI (**) Critical factor (K=2.4) and damping ratio (h=1.5%) values are used.(***) The critical factor depending on the volume flow rate quality (R3)damping which consist of the structural damping, two-phase damping, damping is used.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 92 of 474 S023-(is used. The total and squeeze film 317-1-M1538, REV. 0 Non-proprietary Version(}(P.2-3)Document No.L5-04GA564(9)

At 3. Assumption (1) Nominal tube thickness and nominal tube length are used in the evaluation model because the effect of the tolerances of these dimensions on the natural frequency is negligible.

(2) Contact condition between tube and tube support plate is pin-supported.

Fixed supported condition at No. 1 TSP is added.(3) Contact condition between tube and active support points by the anti-vibration bar (AVB) is pin-supported.

And all points are active.(4) Modulus of elasticity of tube is interpolated based on the tube average temperature of:: from table of ASME Boiler and Pressure Vessel Code, Sec II, Materials, 1998 2 Edition, 2000 addenda (Ref.23).Where, Tav Primary side average temperature (OF)T, Secondary side temperature (OF)(5) Tube has the virtual added mass supposing the fluid-structure interaction (FSI) effect as shown in the following formula (Ref.24)." v I2a. .(D , J' (Ibm /ft) .................................................................

(1)D D O= 1+ P D O P D ........................................................................

(2)Where, m, -Virtual added mass per unit length due to FSI effect;p : Average density of water outside the tube;D .*Tube outside diameter P Tube pitch.4 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 93 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version (}(P.2-4)Document No.L5-04GA564(9)

4. Acceptance criteria Through the tube vibration analysis of the tube straight portion, the stability ratio to FEI is calculated.

A stability ratio over 1.0 implies probability of FEl.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 94 of 474 S023-617-1-M1538, J. 0 I Non-proprietary Version I (P.2-5)Document No L5-04GA564(9)

5. Design input The nominal dimensions are obtained from the design drawings (Ref.3 to 20) and the manufacturing tolerances are not considered.

Flow characteristics are obtained from 3 dimensional thermal and hydraulic analysis (see Appendix 12) .Flow velocity, density, void fraction and hydrodynamic pressure are evaluated for representative 7 tubes (Table 5-1). The reason of selection of these tubes is provided in section 6.2.1.The velocity, density distribution and volume flow rate quality for tube straight portion are provided in Fig.5-0 through 5-21.The void fraction and velocity on the center vertical plane is provided in Fig.5-22.The void fraction and velocity above each TSP are provided in Fig.5-24 through 5-31.Table 5-1 Evaluated Tubes Row Column 1 1 1 13 1 89 53 57 80 74 101 29 137 77 (See Fig. 5-23)Out-of-plane gap velocity In-plane gap velocity (+-) : , HOT COLD 0 .Vgap = Vs " P/(P-D)Vgap gap velocity Vs :superficial velocity P tube pitch D tube outside diameter Fig.5-0 Definition of velocity direction MITSUBISHI HEAVY INDUSTRIES, LTD.Page 95 of 474 S023-617-1-M1538, REV.0 Non-proprietary VersionI}(P.2-6)Document No.L5-04GA564(9)

AO Fig.5-1 Cross flow velocity of tube straight portion (R1 C1 tube)Fig.5-2 Density of tube straight portion (R1 C1 tube)Fig.5-3 Volume flow rate quality (R1 C1 tube)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 96 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version (](P.2-7)Document No.L5-04GA564(9)

At Fig.5-4 Cross flow velocity of tube straight portion (R1 Cl 3 tube)Fig.5-5 Density of tube straight portion (R1 C1 3tube)Fig.5-6 Volume flow rate quality (R1 C13 tube)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 97 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version 1 j (P.2-8)Document No.L5-04GA564(9)

Fig.5-7.Cross flow velocity of tube straight portion (R1 C89 tube)Fig.5-8 Density, of tube straight portion (R1 C89 tube)Fig.5-9 Volume flow rate quality (R1 C89 tube)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 98 of 474 S023-617-1-M1538, RE\f. 0 Non-proprietary Version j](P.2-9)Document No.L5-04GA564(9)

Ak Fig.5-10 Cross flow velocity of tube straight portion (R53C57 tube)Fig.5-11 Density of tube straight portion (R53C57 tube)-1 Fig.5-12 Volume flow rate quality (R53C57 tube)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 99 of 474 S023-617-1-M1538, REV. 0 Non-proprietary VersionI(P.2-1 Document No.L5-04GA564(9)

AFu Fig.5-1 3 Cross flow velocity of tube straight portion (R80C74 tube)/I, Fig.5-14 Density of tube straight portion (R80C74 tube)Fig.5-15 Volume flow rate quality (R80C74 tube)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 100 of 474 SO: 23-617-1-M1538, REV. 0 I Non-proprietary Version I j (P.2-19)Document No.L5-04GA564(9)

-/Fig.5-16 Cross flow Velocity of tube straight portion (R1 01 C29 tube)I--/Fig.5-17 Density of tube straight portion (R1 01 C29 tube)Fig.5-18 Volume flow rate quality (R101C29tube)

MITSUBISHI HEAVY INDUSTRIES, LTD.Page 101 of 474, S023-617-1-M1538, REV. 0 Non-proprietary VersionI(P.2-1 Document No.L5-04GA564(9)

Ak Fig.5-19 Cross flow velocity of tube straight portion (RI 37C77 tube)Fig.5-20 Density of tube straight portion (R1 37C77 tube)Fig.5-21 Volume flow rate quality (R1 37C77 tube)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 102 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version ()(P.2-13)Document No.L5-04GA564(9)

Fig.5-22 Distribution of void fraction and velocity r-.1 Fig.5-23 Evaluated tubes MITSUBISHI HEAVY INDUSTRIES, LTD.Page 103 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version (P.2_14 Document No.L5-04GA564(9)

Fig.5-24 Distribution of void fraction and velocity above tube sheet MITSUBISHI HEAVY INDUSTRIES, LTD.Page 104 of 474 S023-617-1-M1538, V. 0 Non-proprietary Version I j(P.2-1 5)Document No.L5-04GA564(9)

Ak (Note 1)Note that velocity of contour may mislead, because the velocity of outer circumference of the tube bundle is shown in lower velocity compared to that calculated by ATHOS/SGAP.

The accurate values are provided in Appendix-2 Attachment-2.

MITSUBISHI HEAVY INDUSTRIES, LTD.Page 105 of 474 S023-617-1-M1538, RE V. 0 Non-proprietary Version I(P.2"6 j(.-6)Document No.L5-04GA564(9)

A_Fig.5-25 Distribution of void fraction and velocity at #1iTSP MITSUBISHI HEAVY INDUSTRIES, LTD.Page 106 of 474 S023-617-1-M1538, REN/.0 Non-proprietary Version(I)(P.2-17)Document No.L5-04GA564(9)

A&Fig.5-26 Distribution of void fraction and velocity at #2TSP MITSUBISHI HEAVY INDUSTRIES, LTD.Page 107 of 474 S023-617-1-M1538, RE V. 0 FNon-proprietary Version (j(P.2-18)Document No.L5-04GA564(9)

At Fig.5-27 Distribution of void fraction and velocity at #3TSP MITSUBISHI HEAVY INDUSTRIES, LTD.Page 108 of 474 S023-617-1-M1538, RE\,. 0 I Non-proprietary Version]-S(P.2-19)Document No.L5-04GA564(9)

Ak Fig.5-28 Distribution of void fraction and velocity at #4TSP MITSUBISHI HEAVY INDUSTRIES, LTD.Page 109 of 474 S023-617-1-M1538, RE V. 0 Non-proprietary Version(I j(P.2-20)Document No.L5-04GA564(9)

Ak Fig.5-29 Distribution of void fraction and velocity at #5TSP MITSUBISHI HEAVY INDUSTRIES, LTD.Page 110 of 474 S023-617-1-M1538, RE\1.0 Non-proprietary Version )(P.2-21 Document No.L5-04GA564(9)

Ak Fig.5-30 Distribution of void fraction and velocity at #6TSP MITSUBISHI HEAVY INDUSTRIES, LTD.Page 111 of 474 S023-617-1-M1538, RE V. 0 Non-proprietary Version I(P.2-22)Document No.L5-04GA564(9)

Ak Fig.5-31 Distribution of void fraction and velocity at #7TSP MITSUBISHI HEAVY INDUSTRIES, LTD.Page 112 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version,!(P.2-23)

Document No.L5-04GA564(9)

Ak 6. Methodology

6.1 Fluid

elastic instability

6.1.1 Basic

equation of tube vibration analysis The term "fluid elastic instability" is generally used to refer to self-excited vibration of tube bundles due to cross flow. In 1969, Connors disclosed the presence of this phenomenon for the first time (Ref.24).Causes of fluid elastic instability are considered to be the absorption of flow energy due to the interaction of fluid and structure.

This phenomenon occurs on tube bundles, and is subjected to effects of tube bundle array. Thus, it is experimentally attempted to determine the criticality of occurrence in various tube bundle arrays.The critical flow velocity U. for generating fluid elastic instability is obtained in the following Connors' formula (Ref.24).

This formula is employed in the TEMA (Standards of the Tubular Exchanger Manufactures Association), which is the industrial design standard in the United States.vo Kl "1/2 U~ K[ T 2..............................................................(3).

fDo 3 Where, U, :Critical flow velocity f Tube natural frequency D. :Tube outside diameter K Critical factor M0 :Average tube mass per unit length 6 Tube logarithmic decrement(=

2-rh)h Damping ratio Po Density of water outside the tube The critical flow velocity Uc in eq. (3) is evaluated in case of tube vibration of single degree of freedom system with uniform cross flow along the tube axis. In actual tube, however, the vibration of the tube supported by the tube support plate is multi degrees of freedom system with beam type of vibration modes. Therefore, considering the vibration mode and fluid distribution, the effective flow velocity U,, is evaluated in the following formula.Lp(X) U(x)2 (X)2 dx112 o .. ............................................. ...... .(4)fL (x) 2dx o o MITSUBISHI HEAVY INDUSTRIES, LTD.Page 113 of 474 S023-617-1-M1538, RE%,.0 Non-proprietary Version )(P2-24)Document No.L5-04GA564(9)

At Where, Uen (Pn(x)p(x)m(x)U(x)x Po mo L Nth mode effective flow velocity Nth vibration mode:Fluid density distribution of water outside the tube in tube axis direction Tube mass distribution per unit length in tube axis direction Flow velocity distribution orthogonal to tube axis in tube axis direction Coordinate component along tube axis Average density of water outside the tube Average tube mass per unit length Tube length The stability ratio is determined as follows in each vibration mode by calculating the ratio of eq. (3)and eq. (4).SR,, U .........................................................

(5)Ucn where, 1/2 f .-0 ..................................................................................

(6)This value is called the n-th mode stability ratio SRn, and if SR, > 1, fluid elastic instability occurs. Generally, the maximum stability ratio in each mode is called the stability ratio of the tube, which is simply expressed as SR.MITSUBISHI HEAVY INDUSTRIES, LTD.Page 114 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version (P.2-25)Document No.L5-04GA564(9)

At 6.2. Critical factor and damping ratio It is considered that the ASME code provides the conservative critical factor and damping ratio for the low void fraction region such as the tube straight region (Conservative case). In order to calculate the more realistic stability ratio, we can use the best estimated critical factor and the damping factor.6.2.1 Conservative case K=2.4 of the critical factor and h=1.5 % of damping ratio are used as recommended in ASME Sec.lll Appendix N-1330 as a code calculation.

6.2.2 Best estimated case Best estimated values based on recent experiential data are used in this case as follow.6.2.2.1 Damping ratio The damping ratio is calculated as the sum of the structural damping. (1.0%), two phase damping, and squeeze film damping.h = hs T + hTp + hs F ...............................................................................................

(7)where h : Total damping ratio hsT: Structural damping ratio hTp Two phase damping ratio hSF: Squeeze film damping ratio MITSUBISHI HEAVY INDUSTRIES, LTD.Page 115 of 474 S023-617-1-M1538, RE V. 0 I Non-proprietary Version I)(P.2-26)Document No.L5-04GA564(9)

A (1) Structural damping Since MHI test result (Figure 6.2-1, Ref.26) show the average structural damping value is 1.0% (0.2% in minimum), 1.0% is used for the evaluation.

5.0 4.5 4. 0 3. 5 3.0= 2. 5 2.0 1. 5 0. 5 0. 0~~S ~ a a average 0.0 0.1 AmOlitude (mm)Fig.6.2-1 Structural Damping 0.2 MITSUBISHI HEAVY INDUSTRIES, LTD.Page 116 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I(P.2-27)Document No.L5-04GA564(9)

At (2) Two-phase damping Pettigrew's test result of the two phase damping (Figure 6.2-2, Ref.27), which is the function of superficial void fraction, is used to calculate the effective two-phase damping along the tube length by considering vibration mode using the following equation.f h Tp(,6(X))02dX(8 f............2dX.......................................................(8) f ¢b 2 dx Where, hTp x* Two-phase damping* Superficial void fraction* Vibration mode* Tube axis E CO 5 a)ch 2 C1_CO, E 8 0 A3* 0 0 A/ a 0 V Air-Waere stoarm-Water Freon* Narmn Triangle A Normal Triangle

Froon-22 (NT)* Rotated Triangie VI Rotated Triangle 0 Freon-22 (RT)0 Normal U Normal Square 0 Frcon-I 1 (RT)* Rolated Sc"qre 0 20 40 60 80 100 Void Fraction (%)(Grr)OD = C7p(p 1 D2/i)-' ([I + (D/D,)']/[I

-(D/De)2]2}-r Fig 6.2-2 Effect of void fraction on two-phase damping MITSUBISHI HEAVY INDUSTRIES, LTD.Page 117 of 474 S023-E 317-1-M1538, REV. 0 I Non-proprietary VersionI (P.2-28)Document No.L5-04GA564(9),AJý(3) Viscous damping Since the viscous damping is negligible in high void fraction (Ref.28), it is neglected in this analysis.(4) Squeeze film damping Squeeze film damping takes place at the supports and the following equation is based on the available experimental data. (Ref.27)...N.m)l , ]................................

9)NhsF. ..........

Where, hSF P D N f L Im Squeeze film damping Homogeneous density Tube outside diameter Number of the support Natural frequency Support thickness Characteristic tube length MITSUBISHI HEAVY INDUSTRIES, LTD.Page 118 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version )(P.2-29)Document No.L5-04GA564(9) 6.2.2.2 Critical Factor (1) Effect of the void fraction Based on MHI experimental data (Ref.30), the critical factor K is evaluated using the equation shown in Figure 6.2-3 which indicates the relation between the superficial void fraction and the critical factor. This experiment was performed under two-phase flow condition using the straight tube bundle of the triangular pitch as shown in Table 6.2-1 and Fig.6.2-4.

The effective superficial void fraction along the tube length is calculated by considering vibration mode and using the following equation in the same manner as the two-phase damping. The obtained critical factor obtained is K, when the value of P/D is 1.33.= ...............

..............

(10)f 2dX(... .............................................................................

(1 1 )MITSUBISHI HEAVY INDUSTRIES, LTD.Page 119 of 474 S023-617-1-M1538, RE V. 0 Non-proprietary Version )(P.2_30)Document No.L5-04GA564(9)

Fig.6.2-3 MHI Experimental Test Result (Relation between Critical Factor and Superficial Void Fraction)MITSUBISHI HEAVY INDUSTRIES, LTD.Page 120 of 474 S023-617-1-M1538, RE\(.0 Non-proprietary Version 3 (p.231)Document No.L5-04GA564(9)

At Table 6.2-1 MHI Test Condition Tube diameter Tube pitch Number of tubes Flow condition Pressure Temperature Superficial void fraction Fig.6.2-4 MHI Test Equipment MITSUBISHI HEAVY INDUSTRIES, LTD.Page 121 of 474 S023-617-1-M1538, REV. 0 Non-proprietary VersionI(P.2-32)

Document No.L5-04GA564(9) 6.3. Flow of the evaluation Evaluation of occurrence of fluid elastic instability in U-tubes is carried out in the following steps (D Using a 1-dimensional Thermal and Hydraulic parameter code (SSPC), determine the tube bundle circulation ratio and other secondary side operating conditions for the normal operating condition (Ref.21).© Using the flow analysis code (ATHOS/SGAP), determine the distributions of flow velocity U(x) and density of the fluid p(x) along the tube axis.( For the damping ratio h and critical factor K, the suggested values based on ASME Sec III Appendix N-1 330 are used in conservative case, or eqs. (7), (11) are used in the best estimated case. And from eqs. (3) -(5) stability ratio is evaluated (Ref.25)Figure 6.3-1 describes this process.Design Input I Operating conditions SSPC Circulation Ratio Calculation by evaluating pressure loss and recirculation head I ATHOS/SGAP Thermal Hydraulic Analysis 3 dimensional flow distribution-Flow velocity-Flow density-Void fraction FIVATS , F_ Evaluation of fluid elastic instability Fig.6.3-1 Flow of the evaluation MITSUBISHI HEAVY INDUSTRIES, LTD.Page 122 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version(I)(P.2-33)Document No.L5-04GA564(9)

Ak 6.4 Evaluation Parameters In general, larger thermal power is more severe for vibration, because the steam flow rate increases.

At constant thermal power, lower steam pressure is more severe for vibration than higher pressure,'because pU 2 increases

-(the lower p causes the higher U).Basic parameters required for calculations are shown in Table 6.4-1.Table 6.4-1 Basic parameters for calculation Condition of Cycle 16 Plugging Tcod ('F)Thot (Tsg-in) (0 F)Tsg-out (°F)Tfeedwater (oF)Saturation Steam Pressure (psia)Steam Mass Flow (Ib/hr)Circulation ratio Thermal power (MWt/SG) _- _ .-_MITSUBISHI HEAVY INDUSTRIES, LTD.Page 123 of 474 S023-617-1-M1538, REV. 0 Non-proprieta Version (P.234)Document No.L5-04GA564(9)

Ak 6.5 Evaluation of fluid elastic instability

6.5.1 Selection

of tubes to be evaluated The locations of Tube-to-TSP wear at tube straight portions detected in SONGS-2/3 RSGs are shown in Fig. 6.5-1 thorough 6.5-4. In all SGs, tube-to-TSP wear is present in many Row 1 tubes that border on the tube-free-lane.

In addition many of the tubes on the bundle periphery with large bend radii (i.e. Rows 131-142) of 2B-SG exhibit tube-to-TSP wear.Table 6.5-1 through Table 6.5-3 provides the maximum 10 tube wear depth in each SG. The tube-to-TSP wear distributions at each TSP elevation in each RSGs are provided in Appendix-2 Attachment-1.

Among Rowi tubes, the tube on the bundle periphery (Row 1 Column 1), the tube in column center region (RiC89), and the tube outside of the column region (R1C13) are selected for evaluation.

Note that R1C1 tube has the second deepest wear indication at the TSP.Among bundle periphery tubes, the tube which has the largest wear depth in peripheral tubes (R1 37C77) and the tube in the middle (R101C29) are selected for evaluation.

In the tube bundles, the tube which has the largest wear depth in all tubes (R80C74) and the tube in the middle of column (R53C57) are selected for evaluation.

As shown in Fig. 5-23, it is considered that the selected tubes cover wide range of tube bundle.In general, the tube is supported byAVBs so that the tube vibration in U-bend region does not have much effect on the tube vibration of the tube straight part. Thus, the tube vibration model simulating only tube straight part is used for the evaluation.

MITSUBISHI HEAVY INDUSTRIES, LTD.Page 124 of 474 S023-617-1-M1538, REV. 0 Non-proprietary VersionI (P.2-35)Document No.L5-04GA564(9)

Table 6.5-1 Max.10 Tube-to-TSP wear depth in 2A-SG Table 6.5-2 Max.10 Tube-to-TSP wear depth in 2B-SG MITSUBISHI HEAVY INDUSTRIES, LTD.Page 125 of 474 S023-617-1-M1538, RE'V. 0 Non-proprietary Version I(P.2-36)Document No.L5-04GA564(9)

A-Table 6.5-3 Max. 10 Tube-to-TSP wear depth in 3A-SG/I--Table 6.5-4 Max.10 Tube-to-TSP wear depth in 3B-SG MITSUBISHI HEAVY INDUSTRIES, LTD.Page 126 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version]D(P.2-37)Document No.L5-04GA564(9)

Ak B06 ; B07 HOT COLD MITSUBISHI HEAVY INDUSTRIES, LTD.Page 127 of 474 S023-617-1-M1538, REV. 0 Legend*TSP 1-10%*:TSP 11'-20%x x w C-C-C-S C-.z ua U EIN Ft4 uELN 0 0 CD Fig. 6.5-1 Tube-to-TSP wear in 2A-SG Legend C:0%0! TSP 1'-10%* :TSP 11-20%x x CD I-l-44 C-40 ---0-4 0 4ERUE-1OlBELN 90 ---_ --_ --_Fig. 6.5-2 Tube-to-TSP wear in 2B-SG Eý Legend C -0*:TSP 1'-10%0: TSP 11-20%0: TSP 21-309 k T X IUTITITTITITiITT FIFTTTIiU111fni11 CA w z CO)-I m 0 0 0*0)r'z.7 ,0 0 Fig. 6.5-3 Tube-to-TSP wear in 3A-SG Legend: OX e:TSP * :TSP 11-20%x x m i-i 01..........

.CU IMNnE C CFNOTBEL-Fue I-L-IS)-0z 90 __________ -j- TE! UNE CFNO TUBE LANW ___Fig. 6.5-4 Tube-to-TSP wear in 3B-SG 1RýT 0 0 0 C CD Non-proprietary Version )(P.2-42)Document No.L5-04GA564(9)

Ak 7. Results (1) Conservative case The vibration analysis results in case of conservative case (K=2.4, h=1.5%) are shown in Table 7-1 and Fig. 7-1 through 7-3. The maximum stability ratio is 0.67 for R1C1 tube in hot leg. Since the stability ratios are less than 1.0, the analyses imply no FEI occurrence of tube straight portion.Table 7-1 Stability ratio (conservative case)Tube Leg Mode Frequency Critical velocity Effective velocity Stability (Hz) (ft/s) (ft/s) ratio Row Column 1 1 COLD HOT 1 13 COLD HOT 1 89 COLD HOT"53 57 COLD HOT 80 74 COLD HOT 101 29 COLD HOT 137 77 COLD HOT J MITSUBISHI HEAVY INDUSTRIES, LTD.Page 132 of 474 S023-617-1-M1538, REV. 0 I Non-proprietary Version I D(P.2-43)Document No.L5-04GA564(9)

Ak (a) Hot side (b) Cold side Fig.7-1 Vibration mode diagram for R1C1 tube MITSUBISHI HEAVY INDUSTRIES, LTD.Page 133 of 474 SC)23-617-1-M1538, REV. 0 Non-proprietary Version I(P.2-44)Document No.L5-04GA564(9)

Ak (a) Hot side (b) Cold side Fig.7-2 Vibration mode diagram for R80C74 tube MITSUBISHI HEAVY INDUSTRIES, LTD.Page 134 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version (P.2_45)Document No.L5-04GA564(9)

A, (a) Hot side (b) Cold side Fig.7-3 Vibration mode diagram for R137C77 tube MITSUBISHI HEAVY INDUSTRIES, LTD.Page 135 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version )(P.2-46)Document No.L5-04GA564(9)

At (2) Best estimated case In this case, the best estimated critical factors and damping ratios are calculated based on the recent experimental data. The critical factor and damping ratio are provided in Table 7-2.Table 7-2. Critical factor and damping ratio(refined case)Tube Leg Mode Frequency Critical Two phase Squeeze film Total (Hz) factor damping (%) damping (%) damping Row Column (%)(1)1 1 COLD __HOT 1 13 COLD HOT 1 89 COLD HOT 53 57 COLD HOT 80 74 COLD HOT 101 29 COLD HOT 137 77 COLD_oH O_(1) Total damping = (Structural damping [1.0%]) + (two phase damping) + (squeeze film damping).MITSUBISHI HEAVY INDUSTRIES, LTD.Page 136 of 474 S023-617-1-M1538, REV. 0 Non-proprietary VersionI(P.2-47)

Document No.L5-04GA564(9)

Ak The vibration analysis results in case of refined case (K and h are calculated in detail) are shown in Table 7-3 and Fig. 7-4 through 7-6. The maximum stability ratio is [ ]for R1C89 tube in hot leg. Since the stability ratios are less than 1.0, the analyses imply no FEI occurrence of tube straight region.The tube inspection identified the largest tube-to-TSP wear at R80C74 at hot #3-TSP. On the other hand, the calculated stability ratio for R80C74 is [ ], which is not so large compared to the other tubes. In addition, the tube inspection identified the relatively large tube wear in Row1 tubes in cold leg. However, the stability ratios of Row1 tubes in cold side are smaller than those in hot side. It is evaluated that the stability ratio evaluation does not match the tube wear inspection results. Thus, MHI concludes that the cause of tube-to-TSP wears in SONGS-2/3 RSGs is not due to FEI in the straight portion of tube due to the cross flow.Table 7-3 Stability ratio (refined case)Tube Leg Mode Frequency Critical velocity Effective velocity Stability (Hz) (ft/s) (ft/s) ratio Row Column 1 1 COLD -HOT 1 13 COLD HOT 1 89 COLD HOT 53 57 COLD HOT 80 74 COLD HOT 101 29 COLD HOT 137 77 COLD HOT _MITSUBISHI HEAVY INDUSTRIES, LTD.Page 137 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version (D(P.2-48)Document No.L5-04GA564(9)

Ak (a) Hot side (b) Cold side Fig.7-4 Vibration mode diagram for R1C1 tube MITSUBISHI HEAVY INDUSTRIES, LTD.Page 138 of 474 SC)23-617-1-M1538, REV. 0 I Non-proprietary Version I D(P.2-49)Document No.L5-04GA564(9)

At (a) Hot side (b) Cold side Fig.7-5 Vibration mode diagram for R80C74 tube MITSUBISHI HEAVY INDUSTRIES, LTD.Page 139 of 474 SO,?3-617-1-M1538, REV. 0 Non-proprietary Version I(P.2_50)Document No.L5-04GA564(9)

Art (a) Hot side (b) Co Fig.7-6 Vibration mode diagram for R137C77 tube MITSUBISHI HEAVY INDUSTRIES, LTD.Id side Page 140 of 474 S023-617-1-M1538, REV. 0 Non-proprietary Version)I(P.2-51 Document No.L5-04GA564(9)

AO 8. References

1) Deleted 2) Deleted 3) L5-04FU001 the latest revision, Component and Outline Drawing 1/3 4) L5-04FU002 the latest revision, Component and Outline Drawing 2/3 5) L5-04FU003 the latest revision, Component and Outline Drawing 3/3 6) L5-04FU021 the latest revision, Tube Sheet and Extension Ring 1/3 7) L5-04FU022 the latest revision, Tube Sheet and Extension Ring 2/3 8) L5-04FU023 the latest revision, Tube Sheet and Extension Ring 3/3 9) L5-04FU051 the latest revision, Tube Bundle 1/3 10) L5-04FU052 the latest revision, Tube Bundle 2/3 11) L5-04FU053 the latest revision;Tube Bundle 3/3-12) L5-04FU111 the latest revision, AVB assembly 1/9 13) L5-04FU112 the latest revision, AVB assembly 2/9 14) L5-04FU113 the latest revision, AVB assembly 3/9 15) L5-04FU114 the latest revision, AVB assembly 4/9 16) L5-04FU115 the latest revision, AVB assembly 5/9 17) L5-04FU116 the latest revision, AVB assembly 6/9 18) L5-04FU117 the latest revision, AVB assembly 7/9 19) L5-04FU118 the latest revision, AVB assembly 8/9 20) L5-04FU 119 the latest revision, AVB assembly 9/9 21) L5-04GA510 the latest revision, Thermal and Hydraulic Parametric Calculations

22) Vibration analysis of shell-and-tube heat exchanger:

an overview -Part 1 :flow, damping, fluidelastic instability, M.J. Pettigrew, C.E. Taylor, Journal of fluids and structural 18 (2003)469-483 23)ASME Boiler and Pressure Vessel Code, Sec II, Materials, 1998 Edition through 2000 addenda.24) Connors, H.J., Fluid Elastic Vibration of Tube Arrays Excited by Cross Flow, ASME Annual Meeting, 1970.25) Blevins, R. D., "Flow-induced Vibration", Krieger Publishing Company.26)T. Nakamura, et al., "An advanced method to estimate fluid elastic instability of steam generator U-bend tube bundle.", ASME PVP 2001 27) M.J. Pettigrew.,et.al.,2003,"Vibration analysis of shell-and-tube heat exchangers" Journal of Fluids and Structures 18 (2003) 469-483 28)S. M. Fluit and M. J. Pettigrew, "Simplified method for predicting vibration and fretting-wear in nuclear steam generator U-bend tube bundle", ASME PVP 2001 29) M.J. Pettigrew.,et.al.,2000, "The effects of tube bundle geometry on vibration in two-phase cross-flow" 30) WJS1 6263, MHI Test Reportof Fluid Elastic Vibration MITSUBISHI HEAVY INDUSTRIES, LTD.Page 141 of 474'S023-617-1-M1538, REV. 0

v t e Letter Sequence Request
TAC:ME9727, (Withdrawn, Closed)
Initiation Request, Request, Request, Request, Request, Request, Request Acceptance Supplement, Supplement, Supplement, Supplement, Supplement, Supplement Administration Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting Questions 21 February 2013 21 February 2013 1 February 2013 20 February 2013 15 March 2013 30 November 2012 10 December 2012 20 December 2012 27 February 2013 18 March 2013 22 March 2013 10 May 2013 Answers 8 January 2013 9 January 2013 9 January 2013 10 January 2013 16 January 2013 21 January 2013 18 January 2013 21 January 2013 17 January 2013 18 January 2013 24 January 2013 25 January 2013 25 January 2013 29 January 2013 31 January 2013 4 February 2013 4 February 2013 6 February 2013 7 February 2013 25 February 2013 25 February 2013 15 March 2013 15 March 2013 20 March 2013 20 March 2013 20 March 2013 20 March 2013 22 March 2013 22 March 2013 22 March 2013 29 March 2013 1 April 2013 2 April 2013 2 April 2013 10 April 2013 15 April 2013 16 April 2013 30 May 2013 Results Withdrawal Other: ML13051A192, ML13051A193, ML13051A197, ML13051A199, ML13074A793, ML13074A794, ML13098A018, ML13098A020, ML13122A145
MONTHYEAR2013-01-25 [Table View]

ML12285A265