ML20195B162

From kanterella
Jump to navigation Jump to search
Attachment 11 - SG-SGMP-17-25-NP, Revision 1, Foreign Object Limits Analysis for the Byron and Braidwood Unit 2 Steam Generators June 2020
ML20195B162
Person / Time
Site: Byron, Braidwood  Constellation icon.png
Issue date: 06/30/2020
From: Phillips J
Exelon Generation Co, Westinghouse
To:
Office of Nuclear Reactor Regulation
Shared Package
ML20196L732 List:
References
RS-20-079 SG-SGMP-17-25-NP, Rev 1
Download: ML20195B162 (64)
v • d • e


Text

ATTACHMENT 11 Byron Station, Units 1 and 2 NRC Docket Nos. STN 50-454 and STN 50-455 SG-SGMP-17-25-NP, Revision 1, "Foreign Object Limits Analysis for the Byron and Braidwood Unit 2 Steam Generators," June 2020 (NON-PROPRIETARY)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 SG-SGMP-17-25-NP June 2020 Revision 1 Foreign Object Limits Analysis for the Byron Unit 2 and Braidwood Unit 2 Steam Generators

@Westinghouse

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 SG-SGMP-17-25-NP Revision 1 Foreign Object Limits Analysis for the Byron Unit 2 and Braidwood Unit 2 Steam Generators Prepared for:

Exelon Nuclear Author's Name: Signature I Date For Sections Joshua R. Phillips *Electronicallv Annroved All Component Engineering & Chemistry Operations Verifier's Name: Signature I Date For Sections John S. Rees *Electronicallv Approved All Component Engineering & Chemistry Operations Manager's Name: Signature I Date For Sections Michael E. Bradley, Manager

  • Electronicallv Annroved All Component Design & Management Programs This document may contain technical data subject to the export control laws of the United States. In the event that this document does contain such information, the Recipient 's acceptance of this document constitutes agreement that this information in document form (or any other medium), including any attachments and exhibits hereto, shall not be exported, released or disclosed to foreign persons whether in the United States or abroad by recipient except in compliance with all US. export control regulations. Recipient shall include this notice with any reproduced or excerpted portion of this document or any document derived from , based on, incorporating, using or relying on the information contained in this document.

©2020 Westinghouse Electric Company LLC All Rights Reserved

  • Electronically Approved Records are Authenticated in the Electronic Document Management System SG-SGMP-17-25-NP June 2020 Revision 1 Page 2 of63
      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Record of Revisions Rev. Date Revision Description 0 October Original issue.

2017 I See EDMS This revision was created to provide updated results for the limiting object categories and sizes in order to extend the inspection intervals to both 3 cycles or 4.5 effective full power years and 4 cycles or 6 effective full power years.

  • Updated the Executive Summary
  • Updated Tables 2-1, 2-2, 5-1, 5-2, 5-3, 5-4 and 5-5
  • Updated Figures 2-1 and 2-3 .
  • Updated Sections 1.2, 2.1, 5.2, 5.3 and 6.3 .
  • Updated Reference 1 to Revision 1.

(Note: Change bars are used in the left margins where substantial or technical changes occurred.

Change bars are not used for editorial changes such as formatting changes and minor non-technical corrections.)

SG-SGMP-17-25-NP June 2020 Revision 1 Page 3 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table of Contents Executive Summary ..................................................................................................................................................... 6 1 Development of Methodology ........................................................................................................................ 8 I .I Background I Purpose .... ............. ... .......... ... .. ........ ...... ....... ... ... .......... ...... .......... ... ... ....... ... .. ... ........ ..... ........ 8 1.2 Foreign Object Classification Methodology .. ..... .. .. ... ....... ...... ....... ... ... ... ....... ...... .... ... ... ... ...... .... ... ........ ... ... 9

1. 3 Flow Zone Selection Methodology .. ... ....... ... ... .......... ............. ... ............. ........ ... ... .......... ... ... ....... ........ ... ... . 10 1.4 Application of the Methodology ... ... ... ... ..... .......... .... .. ....... .... .. .......... .... .. ........... .................... ... ............. ... . 10
1. 5 Method Used to Determine Wear Times ........ ..... ....... .. ..... ...... ...... .. ...... .. ... .... ...... .......... ..... ... ... .... ... ... ... ... . 11 1.5.1 Tube Wear Evaluation Methodology .. ... ... .......... ... ... .......... ... ... ....... ... ... .......... ... ... ....... ... ..... ... ....... ... ... . 11 1.5.2 Tube Wear Evaluation Assumptions .. ... ... ............. ... .......... ... .......... ... ... .......... ... ............. ... ........ .... ...... . 12 1.5.3 Archard Wear Equation ... ...... ......... ....... ... ...... ............. ........ ....... ... .... ............... .. ..... ... .... ............... ....... . 13 2 Foreign Object Type Classification ............................................................................................................. 18 2.1 Summary ofFindings .............. ............. ... .............. ........... .. ... ........ ..... ........... .. ... ........ .. ... ....... ................ .... 18 3 ATHOS Modeling ......................................................................................................................................... 26 3.1 Method ofAnalysis ... ... .......... ... .... ... ... ... ... .... ......... .. .. ......... ..... .. .. ...................... ..... .. ................. .......... ... ... . 26 3.2 Significant Assumptions ....... ... ... ....... ... ... ... ....... ... ... .......... ... .......... ... ... ............... ... ............. ... ... .......... ... ... . 27 3.3 Design Input .. ... ....... ... ............. ... ... ....... ........ ... ....................... ... ............ ............. .... ................ ... .......... ... ... . 28 3.3.1 ATHOS Geometry Model... ....... .......... ....... ... ... ............. ... .......... ... .................. ... ........................ ... .... ... . 28 4 Flow-Induced Vibration Analysis ............................................................................................................... 36 4.1 MethodofAnalysis ........... ... ...... ............. ... ... ... ............. ............. ... ............. .......... ... ... ........... .. ... ... ....... ... .... 36 4.1.1 Boundary Conditions ...... .... ... ... ... ..... ..... ... ............. ... ... ..... ....... ... ... ....... ... ... ... ....... ... ... ............. ... .......... . 36 4.1.2 Turbulence Displacement ...................................................................................................................... 37 4.1.3 Damping in the Straight Leg ...... .. ........ ....... ..... .. ...... ..... .. .. ............ .. .. .......... ... ............. ....... .. .... ... ....... .... 37 4.2 Identification and Evaluation ofLimiting Tube Locations ..... ......... ...................................... .. ..... ....... ... ... . 38 4.3 Significant Assumptions .......... ... ... ....... ... ... .......... ... ... ... .... ... ... ... .. .... ....... ... .. ...... .................... ... .......... ... ... . 38 4.4 Design Input .. ... .... ... ... ... ....... ... ... ....... ... ..... ... ... .......... ............. ................ ............. ................ ... ... .......... ... ... . 39 4.5 Summary ofResults .... ... .... ... ... ... ... .... ... ... ... ........ ........ .... ........ ... ..... .... .... .... ......... ... ..... .... .... ...... ....... ... ... ... . 39 5 Screening Calculations and Zone Map Development (Pre-Outage) ........................................................ .42 5.1 High Flow Regions in the Tube Bundle... ............. ... ...... .... ... ...... ... ..... ...... ..... ........ ... .. ....... ... .. ... ... ... .. ... .. ... . 42 5.2 Screening Calculations ..... ... ... ... .......... ... ....... ..... ....... .... ... ... .. ... ... .. ... .. ... ... ... .. .. ... ... ... ... .. .. ... ... ... .... ... ... ... ... . 42 5.3 Zone Maps .... ... ... ....... ... ... ... .... ... ... ... ....... ... ... ........ .. ... ... ... .. .. ... ... ... .. ... .. ... ... ... .. .. ... ... ... ... .. .. ... ... ... .... ... ... ... ... . 43 6 Foreign Object Classification Process (during Outage) ............................................................................ 55 6.1 General Categories .... ... .... .... .. ... .......... .... .. .................. ............. ... ............. ............. ... ........... .. ... .......... ... ... . 55 6.2 Default Category 1 Foreign Objects .. ... ........... .......... .... ........ .. .. ... ..... .... .. .. ..... ..... .... .. ..... ... .. ... ........ ... .. ... ... 55 6.3 Classification Process .. ...... ... .... ...... ...... .... ... .. ........................ ............................. ................ ... ... ....... ... ... ... . 56 6.4 Method Summary .... ... ... ....... ... ... ... .... ... ... ... ........ ........ ... ..... ........ ... ........ ............. .... ............. ... ... ....... ... ... ... . 58 6.5 Non-Metallic Objects .... ....... ... ... ... ....... ... ... ..... ....................... ............................. ................... ... .......... ... ... . 58 6.6 Recommended Eddy Current lnspectionfor Foreign Object lnteraction ... ... ....... ...... .. ... ...... ... .............. ... . 59 7 References ..................................................................................................................................................... 63 SG-SGMP-17-25-NP June 2020 Revision 1 Page 4 of63
      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 List of Tables Table 2-1. Byron Unit 2 and Braidwood Unit 2 Foreign Object Inventory- Sort by Object Type .. ....... .. 20 Table 2-2. Byron Unit 2 and Braidwood Unit 2 Foreign Object Inventory - Sort by Object Frequency .. 21 Table 3-1. Byron Unit 2 and Braidwood Unit 2 Model D5 SGs: Parameter oflnterest and ATHOS Input Data .... ..... ... ..... .... ...... ... .... .. ........... .. ...... .. ....... .... ...... ...... ... ....... ........ ..... ..... .. ....... .... .... ....... .. 31 Table 4-1. Byron Unit 2 and Braidwood Unit 2 Analyzed Limiting Tube Locations - FIV Summary ... .. 40 Table 5-1. Limiting Foreign Objects Sizes at the HL TTS and B-Plate High Flow Zone for Two-, Three-,

and Four-Cycle SG Inspection Intervals .............................................................................. 45 Table 5-2. Limiting Foreign Objects Sizes at the CL TTS High Flow Zone for Two-, Three-, and Four-Cycle SG Inspection Intervals ... ..... ....... ............ ....... ........ .. ..... ......... ... ... .. .... ... ..... ....... 46 Table 5-3. Limiting Foreign Objects Sizes at the HL TTS and B-Plate Transition and Low Flow Zone for Two-, Three-, and Four-Cycle SG Inspection Intervals .. ... .... ........... ................ .. ........... .... .. 47 Table 5-4. Limiting Foreign Objects Sizes at the CL TTS Transition and Low Flow Zone for Two-,

Three-, and Four-Cycle SG Inspection Intervals ........................................................... ...... 48 Table 5-5. Limiting Foreign Objects Sizes at the FDB Transition and Low Flow Zone for Two-, Three-,

and Four-Cycle SG Inspection Intervals ............................................. ............................... .. 49 List of Figures Figure 1-1. Loose Part Orientation Near the Top of the TubesheetC1l .. ...................................................... 16 Figure 1-2. Loose Part Orientation Near the Top of the Tubesheet, FDB and Preheater B-Plate ...... ....... 16 Figure 1-3. Loose Part Tube Wear Orientations Considered ..................................................................... 17 Figure 2-1. Byron Unit 2 Foreign Object Type Distributions ............... .. ......................... .. ..... .. ................. 22 Figure 2-2. Braidwood Unit 2 Foreign Object Type Distributions ................. .. ....................................... .. 23 Figure 2-3. Byron Unit 2 and Braidwood Unit 2 Wire Diameter Distribution .. .............. .. ..... .. ................. 24 Figure 2-4. Examples of Objects Observed in the Byron and Braidwood Unit 2 SGs .. ....... .... ........ .. ..... .. 25 Figure 3-1. Schematic of Westinghouse Model D5 Steam Generator .. ..... ..... .... ... ....... ... .. ..... .... ... .......... .. 33 Figure 3-2. ATHOS Finite Difference Grid: Vertical Nodalization ........................ ........... .... .. ................. 34 Figure 3-3. A TH OS Finite Difference Grid: Horizontal Nodalization .. ......... .. ...................... .. ................. 35 Figure 4-1. Byron Unit 2 and Braidwood Unit 2 Model D5 Steam Generators - Lower Tube Support Geometry ...... ...... ... ... ....... .. ...... .. ..... ...... .... .. ....... ........ .. ....... ........ ....... .. .... ... ..... ...... . 41 Figure 5-1. Secondary Side Fluid Gap Velocities above the Hot Side Tubesheet.. ................................... 50 Figure 5-2. Secondary Side Fluid Gap Velocities above the Cold Side Tubesheet.. ................................. 51 Figure 5-3. Secondary Side Fluid Gap Velocities above the Hot Side FDB (Plate A) ... ... .... ... ................. 52 Figure 5-4. Secondary Side Fluid Gap Velocities above the Cold Side FDB (Plate A) ............................ 53 Figure 5-5. Secondary Side Fluid Gap Velocities above the Preheater TSP B-Plate ... .... ... ..... ................. 54 Figure 6-1. Example of a Foreign Object that Resulted in a Tube Leak - Sample !.. ...... ....... .................. 61 Figure 6-2. Example of a Foreign Object that Resulted in a Tube Leak- Sample 2 .... .... ...... ........... ........ 62 SG-SGMP-17-25-NP June 2020 Revision 1 Page 5 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Executive Summary Foreign objects have historically been found within the Byron Unit 2 and Braidwood Unit 2 steam generators (SGs) during eddy current inspections and secondary side visual inspections. Some of the objects have caused wear fretting on the SG tubes, resulting in plugging the affected tubes and surrounding tubes, and have caused primary-to-secondary leakage and subsequent forced outages at Byron Unit 2 in 1996 and 2002. Additionally, identification of foreign objects have also caused increased outage inspection scope for both eddy current and foreign object search and retrieval (FOSAR) resulting in increased radiation dose received and schedule and cost impacts.

When foreign objects cannot be removed from the SGs, an evaluation must be performed to determine the acceptable duration of continued operation with the object remaining in the SG. The evaluation must consider the impact on tube integrity and the interval of SG inspections. Evaluation of foreign objects remaining in the SGs is required by the Electric Power Research Institute (EPRI) Steam Generator Integrity Assessment Guidelines (Reference 7). This document provides a generic evaluation of commonly found foreign objects to determine a limiting size and location that would be acceptable for either at least two (2), three (3), or four (4) operating cycles (i.e., 3.0, 4.5 , or 6.0 effective full power years (EFPY)) for objects found on the secondary face of the tubesheet, preheater baffle plate (TSP 02C) and the flow distribution baffle. As a disclaimer, this evaluation is limited to the top sides of these surfaces where a large majority of foreign objects have been historically found and does not apply to less common configurations such as where an object wears on a tube below a plate. The assumptions for less common locations would likely be different and are outside the scope of this report, therefore, a separate location-specific evaluation would be needed. During a SG inspection, if all foreign objects meet the predetermined acceptance criteria provided in this document, no additional evaluations would be required.

This evaluation would aid to alleviate the emergent short turnaround work during SG inspections for objects that meet the predetermined acceptance criteria established and would form a basis for more efficient and refined analysis for the evaluation of objects not meeting the initial acceptance criteria.

This document also provides recommendations and guidance for a foreign object retrieval prioritization strategy for foreign objects found during FOSAR. The prioritization strategy is based on the guidance provided in the EPRI Foreign Object Prioritization Strategy for Square Pitch Steam Generators (Reference 4). The strategy provides a ranking system that can be used as a guide to assist in identifying the order in which the objects should be removed from the steam generators during an inspection. This ranking will use the same three (3) categories developed for use in the EPRI studies for square pitch steam generator models and are as follows:

SG-SGMP-17-25-NP June 2020 Revision 1 Page 6 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3

  • Category 1 (High)
  • Category 2 (Medium)
  • Category 3 (Low)

Note that in other Westinghouse documents, these three categories may also be referred to as "Priority 1, 2, and 3." This terminology is interchangeable, but for consistency, will be labelled "Category" in this document to match the language used in Reference 4.

Lastly, this document provides recommendations for eddy current inspection of peripheral tubes with the objective of foreign object and tube wear caused by foreign objects located on the secondary face of the tubesheet.

Revision 1 of this report updates the category sizing of wires in accordance with the latest Westinghouse foreign object evaluation methodology.

] a,c,e . As a result, minor changes were made to the limiting object sizes from Revision 0 in order to satisfy 3 effective full power years.

Additionally, this report considers a longer period of time between FOSAR inspection outages. This revision also provides WEART results for up to 4.5 effective full power years, or 3 cycles of operation and 6 effective full power years, or 4 cycles of operation. [

SG-SGMP-17-25-NP June 2020 Revision 1 Page 7 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 1 Development of Methodology 1.1 Background I Purpose Foreign Object Search and Retrieval (FOSAR) is typically performed on the steam generator secondary side during a refueling outage where the steam generators (SGs) are inspected. These inspections could result in the identification of a number of foreign objects. When large numbers of foreign objects are identified, the characterization and/or removal of all objects results in a significant effort, measured in safety, time and dose. For foreign objects that cannot be removed from the SGs, an evaluation must be performed to determine the acceptable duration of continued operation with the objects remaining in the SG. In many cases, the foreign objects are small or are located in a region of the tube bundle where little or no tube degradation would be expected to occur over multiple cycles of operation. Historically, it had been the practice at Braidwood and Byron to perform foreign object evaluations on an as-needed basis for each instance of a non-retrieved foreign object during the course of the SG inspection. This has created emergent and immediate situations that have required short turnaround evaluations affecting both WEC and Exelon engineering abilities to meet stringent outage schedule demands. To alleviate the emergent short turnaround evaluations and/or reduce the impact of removing inconsequential foreign objects, an evaluation was performed, as documented in this report, which determined limiting foreign object sizes that would be acceptable for continued operation if not removed for object types commonly found within the Byron and Braidwood SGs.

Evaluation and acceptability of a foreign object remaining in the SG is dependent on various factors, such as [

] a,c,e. Historically at Byron and Braidwood, foreign objects have been commonly found on the tubesheet, flow distribution baffle (FDB) and the pre-heater tube support plate (TSP 02C by Exelon nomenclature or Plate B by WEC nomenclature). The majority of the objects have been found on the tubesheet and TSP 02C locations.

Therefore, foreign object acceptable size limits have been established for ten (10) categories of object types located in a high flow zone and a low flow zone at the tubesheet and TSP 02C elevations and in one flow zone on the FDB. The evaluation process can be summarized by the following steps:

1. Trending and categorization of foreign objects found within the Byron and Braidwood Unit 2 SGs to determine the ten (10) categories of object types (i.e. , gaskets, wires, weld slag, etc.) for which to perform the size limit evaluations.
2. Determine the fluid flow characteristics at the tubesheet, flow distribution baffle (FDB) and Tube Support Plate (TSP) 02C elevations through detailed thermal-hydraulic (T-H) analysis.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 8 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3

3. Determine the flow-induced vibration (FIV) characteristics at the tubesheet, FDB and TSP 02C elevations.
4. Determine the boundaries of the high flow zone and low flow zone at the tubesheet and TSP 02C elevations and the limiting flow zone for the FDB elevation based upon the T-H and FIV analyses.
5. Perform wear time calculations to determine the limiting foreign object size for each flow zone, elevation, and object type category.

The remainder of this document provides the detailed descriptions and results of the evaluations described above. Additionally, this document provides recommendations and guidance on the application of the foreign object limits with regards to foreign object retrieval priority strategy and recommendations for tubesheet inspection of peripheral tubes.

1.2 Foreign Object Classification Methodology A review of Byron Unit 2 and Braidwood Unit 2 foreign object logs was performed to determine the more common types of objects, in both size and shape that are generally found during FOSARs. This review consisted of identification of all foreign objects detected on the tubesheet, FDB and TSP 02C elevations during outages where FOSAR occurred from 2000 to 2017, including the most recent Byron Unit 2 outage (B2R20). The Rolls-Royce (R-R) Component Information System (CIS) database and R-R field service reports were used to generate an inventory of all foreign objects detected within the SGs at Byron Unit 2 and Braidwood Unit 2. The inventory of objects was grouped into similar object categories (i.e. ,

gasket, wire, slag, etc.) to determine the frequency of occurrence for each plant. From the frequency of occurrence for each plant, a single list of ten (10) foreign object categories was selected for which to determine the limiting foreign object size limits for each flow zone.

After defining these categories for the Byron and Braidwood SGs, the foreign object sizes are reviewed and basic wear time calculations performed. The purpose of these evaluations is to determine what size a foreign object could be demonstrated as acceptable to remain in the SG secondary side over a given operating interval (which for the SGs typically ranges from approximately 1.5 to 3.0 years, but could extend to 4.5 or 6.0 years in the future). Any foreign object larger than that defined maximum size would therefore be considered for removal from the steam generator in support of a desired SG operating interval between inspections. If removal is not possible, other appropriate actions necessary to demonstrate acceptability for the interval between inspections would need to be performed.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 9 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 1.3 Flow Zone Selection Methodology The SG secondary side fluid flow field is an essential consideration in any foreign object evaluation and the fluid flow velocities vary in both magnitude and direction at a given elevation with the SGs. The thermal-hydraulic analysis supporting the foreign object limits analysis allows for a detailed mapping of the secondary side fluid velocity at any tube location and elevation within the Byron Unit 2 and Braidwood Unit 2 SG tube bundle. This information has been plotted into a secondary side flow map for the hot leg and cold leg tubesheet, flow distribution baffle, and the Preheater B-Plate at 02C. This is done in order to visualize the relative locations of high velocity in comparison to the remainder of the tube bundle.

With this information, an iterative process is taken in determining the foreign object wear time estimates by varying the dimensions of the foreign objects with the fluid velocity. The result is the identification of a threshold between the high flow (red) and low flow (white) regions of the SGs as they pertain to foreign object wear. Specific to Byron and Braidwood Unit 2, a transition region (orange) has also been identified which indicates where the fluid is transitioning from the high flow (red) into the low flow (white) region. Even though the threshold for high flow (red) is not reached in the transition region (orange), these locations are still considered more subject to foreign object wear degradation than the general population and, therefore, considerations should be made for foreign object retrieval attempts.

The flow zone maps resulting from application of this methodology are provided in Section 5.

1.4 Application of the Methodology Determining the actual acceptability of an object with respect to tube wear potential can be difficult before obtaining all relevant information about the actual loose part. Various details of the specific object can influence the judgments made regarding long-term acceptability of secondary side foreign objects.

Some of the relevant information includes such items as:

.[

Because of the many possible combinations of the above, it is generally recognized that making final conclusions regarding the acceptability of an object before all the details of the object are understood can SG-SGMP-17-25-NP June 2020 Revision 1 Page 10 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 be challenging. However, it is possible to recommend a removal sequence for some of the more common objects observed in steam generators. Once the general inventory of typical objects was defined, wear time calculations can be performed to determine the acceptability of these objects for long-term steam generator operation. Since it was not feasible in this report to perform wear time calculations for each part at each location for every tube in the Byron and Braidwood SGs, a set of typical foreign objects assumed to be located at a limiting tube location within each flow zone and elevation was selected for analysis.

1.5 Method Used to Determine Wear Times As described, the amount of tube wear a particular foreign object can cause is dependent on many factors.

Some parts can cause tube leakage simply because they get wedged between tubes in a high flow region.

These same parts might be benign if they reached a low flow region before getting wedged between tubes.

In some cases, the amount of wear (if any) is dependent on the orientation of a part or whether the part is between tubes or behind a tube. Wear is also dependent on the vibrational characteristics of the adjacent tubes.

To determine the basic wear time parameters for the Byron Unit 2 and Braidwood Unit 2 SG design, detailed thermal-hydraulic and FIV evaluations were performed. These evaluations are described in Sections 3 and 4, respectively. By combining these two analyses, it is possible to develop plant-specific input to a proprietary computer code used by Westinghouse to determine wear times for a given foreign object. It uses the Archard equation to determine the volume of metal removed for a given force and sliding distance. Tube vibration parameters (such as natural frequency and associated displacements) are used to obtain the distance and the force is supplied by the local fluid flow conditions. In general, it is assumed the foreign object is in the worst location at or near the periphery of the tube bundle.

1.5.1 Tube Wear Evaluation Methodology The evaluation of the potential for fretting and impact/sliding wear caused by the presence of loose objects remaining in the secondary side of steam generators involves postulating scenarios in which the loose objects contact vibrating tubes and wear into the tubes over significant periods of time. The objective is to estimate the time each loose object would require to wear into a tube until the tube wall no longer meets the minimum wall thickness requirements pertaining to the maintenance of tube integrity.

If loose objects remain in the steam generator tube bundle during operation, the loose objects and the tubes can interact in several ways to produce potential tube degradation. Each of these potential mechanisms for tube degradation is considered in this evaluation. The three (3) potential mechanisms for tube degradation are:

SG-SGMP-17-25-NP June 2020 Revision 1 Page 11 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3

1. Fretting wear - During operation, the steam generator tubes vibrate in the secondary flow field. If a loose object comes into contact with a tube during operation, the tube continues to vibrate. As the tube vibrates back and forth against the loose object, the object wears a groove in the outer wall of the tube. If the loose object and the tube do not lose contact, then this behavior is classified as fretting or sliding-only wear.
2. Impact/sliding wear - If a loose object comes into contact with a vibrating tube during operation, the loose object may have a tendency to frequently lose contact with the tube and then return to the same position against the tube. During the brief intervals in which the loose object is not in contact with the tube, the secondary fluid removes the loose particles at the wear site. When the loose object regains contact with the tube, it has a clean wear site on which to continue the tube wear process as the tube vibrates. Since the debris is continually removed from the wear site during impact/sliding wear, the tube wear progresses at a faster rate than for fretting or sliding-only type wear.
3. Repeated impacting without sliding (impacting only) - Some loose objects have a geometry which allows the secondary flow to lift the objects away from the tube and repeatedly collide against the same site on the tube. If a loose object has sufficient mass and velocity during its collisions with a tube, the energy imparted to the tube may be large enough to cause small dents or deformations in the outer surface of the tube. Some loose objects in operating steam generators have been known to collide with the same tube or tubes for long enough periods of time to cause cumulative and measurable degradation to the tubes. The loose objects bounded by this report are judged to be of insufficient mass to cause significant tube degradation via the repeated impacting without the sliding wear mechanism.

For the purposes of this study, impact/sliding wear will be the basis for analysis and retrieval prioritization of loose parts. This is considered a reasonable approach since all objects will be evaluated on a consistent basis, and impact/sliding wear has been found to be generally more limiting than either pure fretting or impacting only scenarios.

1.5.2 Tube Wear Evaluation Assumptions The loose objects are considered to contact tubes near the top of the tubesheet, the top of the flow distribution baffle and at the Preheater B-Plate. These regions represent the critical locations with respect to the loose objects wearing on the tubes in the Byron Unit 2 and Braidwood Unit 2 SGs. Figure 1-1 contains a sketch of the assumed object location and orientation. ln the Byron Unit 2 and Braidwood Unit 2 SGs, the largest impact resulting from cross flow mixture velocities and fluid densities are experienced at the top of the hot leg top of tubesheet followed by the preheater B-plate, the CL tubesheet SG-SGMP-17-25-NP June 2020 Revision 1 Page 12 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 then the FDB . Hence, the loose objects contact the tubes with the largest drag forces when they reside in the top of the hot leg tubesheet and preheater regions. In addition, the tube vibration amplitudes resulting from turbulence excitation, which directly influence the wear rate, are elevated for the straight leg in these two regions.

For each loose object, [

] a,c,e. A review of photographs of previous objects analyzed and available eddy current sludge mapping data demonstrate the conservatism in this assumption. Although a significant sludge pile has not been reported in the Byron Unit 2 and Braidwood Unit 2 SGs to date, this assumption results in larger amplitudes of tube vibration and produces shorter wear times. A review of the tubesheet secondary side fluid flow for the Byron Unit 2 and Braidwood Unit 2 SGs shows that, [

]a,c,e. A conservative wear coefficient is assumed for all objects. [

] a,c,e which was applied in this analysis.

1.5.3 Archard Wear Equation The basis for the evaluation of loose objects and their potential to cause impact/sliding wear is the Archard wear equation:

V=KFD Where:

V =the volume of material worn from the tube (assuming only the tube wears)

K = the wear coefficient for the two materials in contact F =the contact force between the loose object and the tube D = the distance over which the force acts.

Figure 1-2 contains a sketch of the orientation of the object during the wear process.

] a,c,e. Figure 1-3 depicts the SG-SGMP-17-25-NP June 2020 Revision 1 Page 13 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 loose part wear shapes considered as part of this study which is variable depending on the loose part under consideration.

Relations have been developed to calculate the volume of material which must be worn from the tube wall in order to reach the specified depth into the tube. As previously stated, this wear volume [

y .c,e.

The contact force between the loose object and a tube depends upon [

]a,c,e. This limit is considered conservatively representative of the tube structural limit with material property and burst relation uncertainty for foreign object wear based the Byron Unit 2 and Braidwood Unit 2 structural and condition monitoring limit bases document (Reference 6). This applied limit corresponds to [

]a,c,e. In equation form:

SG-SGMP-17-25-NP June 2020 Revision 1 Page 14 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 V=KFD

= K(FD/t) T

=K(WR)T Rearranging:

T = V/[K(WR)]

Where:

WR =Work Rate, or work (F

  • D) over a given period of time (t)

T = the time required to achieve wear volume "V" Based on the estimated wear times (to the minimum allowable wall), an engineering judgment can be made concerning the potential for tube degradation due to the loose objects wearing on the tubes for a given operating interval.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 15 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 a,c,e Figure 1-1. Loose Part Orientation Near the Top of the Tubesheet< 1>

a,c,e Figure 1-2. Loose Part Orientation Near the Top of the Tubesheet, FDB and Preheater B-Plate SG-SGMP-17-25-NP June 2020 Revision 1 Page 16 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 a,c,e Figure 1-3. Loose Part Tube Wear Orientations Considered SG-SGMP-17-25-NP June 2020 Revision 1 Page 17 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 2 Foreign Object Type Classification 2.1 Summary of Findings As described in Section 1.2, the Byron Unit 2 and Braidwood Unit 2 inventory of foreign objects detected was generated from data obtained from the R-R CIS foreign object logs and field service reports for secondary side FOSAR activities conducted from 2000 to 2017. For Braidwood Unit 2 this included FOSAR inspections from A2R08 (Fall 2000) to A2R19 (Spring 2017) and for Byron Unit 2 this included FOSAR inspections from B2R09 (Spring 2001) to B2R20 (Fall 2017). The inventory included foreign objects removed from the SGs and foreign objects remaining in the SGs. Legacy objects identified subsequent to the initial discovery were deleted from the inventory to eliminate counting the same object multiple times. Revision I of this report added in the additional foreign objects found during the B2R20 (Fall 2017) FOSAR inspections. Excluding legacy objects, the new objects discovered are consistent with those found in previous outages and include three wires, one gasket winding piece, and a waterbox tab.

This tab (referred to as a metal bar in this report) was traced to the waterbox cap plate in the preheater region of Steam Generator 2C and is similar to those found during the B2Rl 1 (Spring 2004) FOSAR inspection.

Table 2-1 provides the number of foreign objects found in the Byron Unit 2 and Braidwood Unit 2 by object type description. A common set of descriptions was used for both plants to provide a side-by-side comparison between the plants. Table 2-2 provides the frequency of foreign object types for each plant and is shown graphically in Figure 2-1 for Byron Unit 2 and Figure 2-2 for Braidwood Unit 2. For both plants, wires have been the most frequent foreign object type; 37% for Byron and 44% for Braidwood.

As shown in Figure 2-3, the majority (~74% of the wires found) have diameters estimated at [ ] a,c,e inch or less. Many of these small diameter wires are found wedged into the crevice between the tube and the pre-heater baffle plate drill hole. The largest wire diameter size reported was estimated at [ ] a,c,e inch ([ ]a,c,e inch) and, in hindsight, an object of this size could have been categorized as a rod.

With the exception of gasket winding material, the types of foreign objects found at both Byron Unit 2 and Braidwood Unit 2 are similar. In descending frequency , the most common objects found in addition to wires are hard sludge/scale, machine turnings, weld slag, metal objects, and weld beads. Other types of objects were found on an isolated or infrequent basis, such as screws, washers, weld rods, bushings, and an assortment other miscellaneous metallic-type objects. At Byron Unit 2, gasket winding material is the second most common object type found (24%), whereas, Braidwood Unit 2 has found only one gasket winding piece to-date. Figure 2-4 contains images of typical loose objects found during the FOSAR efforts during recent inspections.

The majority of the foreign objects found at both units were located on the pre-heater baffle plate TSP 02C (~78%) , followed by the top of the tubesheet (~20%), and then the FDB (~2%). This is due to the SG-SGMP-17-25-NP June 2020 Revision 1 Page 18 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 pre-heater design of the SGs. The pre-heater baffle plate is located where the main feedwater flow first enters the SG. Consequently, the bulk of the foreign objects tend to collect on TSP 02C. Flow that enters at the top of the tubesheet elevation typically originates from the downcomer flow which consists of recirculating flow, flow from the auxiliary feedwater nozzle and to a lesser extent flow from the pre-heater box. During normal operation, [ ] a,c,e of the feed water flow enters the SG in the steam drum area through the auxiliary feedwater nozzle where the flow enters the downcomer region to the top of the tubesheet. [ ] a,c,e of the feedwater flow enters the SG within the pre-heater region at TSP 02C.

Figure 2-4 contains photographs of typical loose objects found during the FOSAR efforts during recent Byron Unit 2 and Braidwood Unit 2 SG inspections.

Following review of the foreign object history at Byron Unit 2 and Braidwood Unit 2 the following ten (10) categories or types of foreign objects were selected for evaluation of foreign object size limitations:

1. Wires _:: ; [ ] a,c,e inch diameter
2. Wires > [ ] a,c,e inch and .:::: [ ] a,c.e inch diameter
3. Gasket winding material
4. Machine turnings
5. Hard sludge/scale
6. Weld slag
7. Weld rod/nails/metallic cylindrical objects
8. Weld beads/metallic balls and spheres
9. Metal objects/strips/bushing/washers/nuts
10. Screws/bolts/threaded objects SG-SGMP-17-25-NP June 2020 Revision 1 Page 19 of 63
      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 2-1. Byron Unit 2 and Braidwood Unit 2 Foreh n Object Inventory- Sort by Object Type Byron Unit 2 Braidwood Unit 2 Description FDB TSP 02C TTS Total Description FDB TSP 02C TTS Total Back Up Bar Back Up Bar 1 1 Back Up Block Back Up Block 2 2 Bushing 1 1 Bushing 1 1 Cloth Fiber Cloth Fiber 1 1 Duct Tape Duct Tape 1 1 Flat Wire Flat Wire 1 1 Furmanite 3 3 Furmanite Gasket 2 93 3 98 Gasket 1 1 Graphite 7 1 8 Graphite 1 1 Hard Sludge/Scale 5 44 35 84 Hard Sludge/Scale 3 81 31 115 Machine Turning 18 3 21 Machine Turning 17 3 20 Mass of Fiber Mass of Fiber 1 1 Metal Bar 3 3 Metal Bar Metal Obiect 3 5 8 Metal Obiect 1 9 3 13 Metal Strip 2 2 Metal Strip 3 1 4 Nail Nail 1 1 Nut 1 1 Nut Screw 1 1 Screw 1 1 Small Wire Clip Small Wire Clip 1 1 Spring 4 4 Spring Tapered Pin Tapered Pin 1 1 Washer 2 2 Washer 1 1 Weld Bead 2 2 Weld Bead 4 1 5 Weld Rod 2 1 3 Weld Rod Weld Slag 5 7 12 Weld Slag 11 5 16 Wire 120 27 147 Wire 1 131 14 146 Total 8 309 83 400 Total 7 264 63 334 SG-SGMP-17-25-NP June 2020 Revision 1 Page 20 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 2-2. Byron Unit 2 and Braidwood Unit 2 Foreie:n Object Inventory- Sort by Object Frequency Byron Unit 2 Braidwood Unit 2 Description FDB TSP 02C TTS Total Description FDB TSP 02C TTS Total Wire 120 27 147 Wire 1 131 14 146 Gasket 2 93 3 98 Hard Sludge/Scale 3 81 31 115 Hard Sludge/Scale 5 44 35 84 Machine Turning 17 3 20 Machine Turning 18 3 21 Weld Slag 11 5 16 Weld Slag 5 7 12 Metal Object l 9 3 13 Graphite 7 1 8 Weld Bead 4 1 5 Metal Object 3 5 8 Metal Strip 3 1 4 Spring 4 4 Back Up Block 2 2 Furmanite 3 3 Back Up Bar 1 1 Weld Rod 2 1 3 Bushing 1 1 Metal Bar 3 3 Cloth Fiber 1 1 Metal Strip 2 2 Duct Tape 1 1 Washer 2 2 Flat Wire 1 1 Weld Bead 2 2 Gasket 1 1 Bushing 1 1 Graphite 1 1 Nut 1 1 Mass of Fiber 1 1 Screw 1 1 Nail 1 1 Back Up Bar Screw 1 1 Back Up Block Small Wire Clip l l Cloth Fiber Tapered Pin 1 1 Duct Tape Washer 1 1 Flat Wire Furmanite Mass of Fiber Metal Bar Nail Nut Small Wire Clip Spring Tapered Pin Weld Rod Total 8 309 83 400 Total 7 264 63 334 SG-SGMP-17-25-NP June 2020 Revision 1 Page 21 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Byron Unit 2 Foreign Objects Detected 2001-2017 160 140 120 tlQI 100

c 0

0 QI 80

""'E

I z 60 40 20

~~ ~" t-if)...~

~

.,,.,;ti' <:>..

~.,

FOB

  • TSP 02C TTS Byron Unit 2 Foreign Objects Detected 2001-2017 Byron Unit 2 Foreign Object Elevation Distribution Weld FOB SI*& -.. 2%

3%

Figure 2-1. Byron Unit 2 Foreign Object Type Distributions SG-SGMP-17-25-NP June 2020 Revision 1 Page 22 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Braidwood Unit 2 Foreign Objects Detected 2000-2017 160 140 120 Ill t; 100

'E 0

SJ 0 80 E

s 60 z

40 20 TIS Bnidwood Unit 2 Foreign Objects Detected 2000*2017 Byron Unit 2 Foreign Object Elevation Distribution Other M et al Stri p Gasket 4%

Weld Bead l% 0%

  • 2% ~ ~

M etal __

M achine Turning 6%

Figure 2-2. Braidwood Unit 2 Foreign Object Type Distributions SG-SGMP-17-25-NP June 2020 Revision 1 Page 23 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 a,c,e Figure 2-3. Byron Unit 2 and Braidwood Unit 2 Wire Diameter Distribution SG-SGMP-17-25-NP June 2020 Revision 1 Page 24 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Wire in Crevice Wire Gasket Winding Machine Turning Weld Slag Hard Sludge Metal Object Weld Bead Figure 2-4. Examples of Objects Observed in the Byron and Braidwood Unit 2 SGs SG-SGMP-17-25-NP June 2020 Revision 1 Page 25 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3 ATHOS Modeling 3.1 Method of Analysis Model DS SG overall performance parameters were calculated using SG-SGMP-17-25-NP June 2020 Revision 1 Page 26 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3

)a ,c,e.

3.2 Significant Assumptions 1.

)a,c,e.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 27 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3.3 Design Input 3.3.1 ATHOS Geometry Model Steam Generator Performance Analysis (GENP Calculations)

The GENP input for Byron Unit 2 and Braidwood Unit 2 with the Model D5 steam generators were obtained from the Thermal and Hydraulic Design Data Reports (References 8 and 9) and the thermal-hydraulic evaluations to support the 3672 MWt nuclear steam supply system (NSSS) uprate program (Reference 10). The SG thermal design operating conditions at the uprated 3672 MWt NSSS power levels are from Reference 11.

Detailed Three-Dimensional A THOS Analysis The ATHOS model of the for Byron Unit 2 and Braidwood Unit 2 with the Model D5 steam generators is from evaluations documented in Reference 12. The ATHOS model requires input data for the geometry pre-processors, ATHOGPP and PLATESD5A, thermal-hydraulic solver, ATHOS, and post-processor, VGUB codes.

A THOS Geometry Pre-processor The geometry model for the Model D5 steam generators includes specifications for the design and geometric details. Details of geometric specifications include the following:

1. [

] a,c,e directions. A schematic of the SG-SGMP-17-25-NP June 2020 Revision 1 Page 28 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Model DS steam generator is presented in Figure 3-1. The finite difference grids in the R-Z and R-8 planes are depicted in Figures 3-2 and 3-3, respectively.

The ATHOS model covers the secondary side flow field inside the steam generator shell from the top surface of the tubesheet to the lower deck plate and from the center of the wrapper to wrapper wall and the downcomer annulus between the wrapper and the shell walls. [

]a,c,e.

PLATESD5 Pre-processor Because of the complexity of the preheater design, [

ATHOS Thermal-Hydraulic Module The ATHOS model for the Byron Unit 2 and Braidwood Unit 2 Model DS SGs includes input data for:

]a,c,e. The ATHOS input data utilized for this analysis are presented in Table 3-1.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 29 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 VGUB Post-Processor The post-processor VGUB calculates SG-SGMP-17-25-NP June 2020 Revision 1 Page 30 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-1. Byron Unit 2 and Braidwood Unit 2 Model DS SGs:

Parameter of Interest and ATHOS Input Data (Reference 12: 3672 MWt, Primary Fluid SG Outlet Temperature= [ ] a,c,e oF, ( ] a,c,e % SGTP)

Parameter Units Value a,c,e SG heat load MWt gpm Primary coolant flow rate per SG Million lb/hr kg/sec 12 SG Of Primary fluid inlet temperature (Used for the target value in ATHOS analysis) Kelvin Of Primary fluid outlet temperature Kelvin psi a Primary fluid operating pressure N/m 2 Primary fluid density kg/m3 Primary fluid viscosity N/m2-sec Primary fluid conductivity W/mK Primary fluid specific heat J/kgK Million lb/hr feedwater flow rate, Pre-heater< 1l kg/sec 12 SG Million lb/hr feedwater flow rate, Downcomer<1l kg/sec 12 SG Steam pressure at nozzle outlet (not used by ATHOS code) psi a psia Steam pressure in the dome<2l N/m 2 Of feedwater temperature Kelvin in Downcomer water level m

Carry-under -

Quality at SG outlet -

Hot and cold side circulation ratios (initial guess) -

SG-SGMP-17-25-NP June 2020 Revision 1 Page 31of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-1. Byron Unit 2 and Braidwood Unit 2 Model DS SGs:

Parameter of Interest and ATHOS Input Data (Reference 12: 3672 MWt, Primary Fluid SG Outlet Temperature= [ ]a,c,e oF, [ ]a,c,e % SGTP)

Parameter Units Value Liquid viscosity N/m2-sec a,c,e Liquid conductivity W/mK Liquid specific heat J/kgK Vapor viscosity N/m2-sec Vapor conductivity W/mK Vapor specific heat J/kgK Surface tension Nim Tube metal (Alloy 600) density<3l kg/m3 Metal (Alloy 600) conductivityC3l W/mK Metal (Alloy 600) specific heatC3l J/kgK Fouling factor<4 l m2/K-W Tube support plate K-factor - Flow Distribution Baffle Tube support plate K-factor - Preheater Baffle Tube support plate K-factor -

Primary separator K-factor< 5l -

Cold side downcomer K-factor<5l -

Hot side downcomer K-factor< 5l -

U-bend hydraulic loss factor -

Notes:

(I) Feedwater I steam flow rate is conservatively calculated to transfer [ ]a,c,e MWt per SG without the blowdown flow rate.

(2) Steam pressure in the dome is calculated from steam pressure at the outlet nozzle and pressure drops through: steam outlet nozzle, secondary separators, and the separator transition region from the GENP output.

(3) Tube metal properties are calculated at average of the secondary fluid saturation temperature and the average primary fluid temperature in the SG.

(4) The heat transfer fouling resistance is adjusted to match the GENP calculated primary side SG inlet temperature of [ ]a,c,e °F within a specified tolerance.

(5) These loss factors are adjusted to match the GENP calculated circulation ratio of [ ] a,c,e and the primary separator pressure drop of [ ]a,c,e psi within a specified tolerance.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 32 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 a,c,e Figure 3-1. Schematic of Westinghouse Model DS Steam Generator (Dimensions are in Inches)

SG-SGMP-17-25-NP June 2020 Revision 1 Page 33 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 a,c,e Figure 3-2. ATHOS Finite Difference Grid: Vertical Nodalization SG-SGMP-17-25-NP June 2020 Revision 1 Page 34 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 a,c,e Figure 3-3. ATHOS Finite Difference Grid: Horizontal Nodalization SG-SGMP-17-25-NP June 2020 Revision 1 Page 35 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 4 Flow-Induced Vibration Analysis 4.1 Method of Analysis Flow-induced vibration (FIV) analyses of the Byron and Braidwood Unit 2 Model D5 generator tube bundle has been performed using the FASTVIB2 computer code. The inputs to the FASTVIB2 computer code were derived from the output files of the ATHOS family of codes described in Section 3, which included the steam generator geometry and the three-dimensional (3-D) thermal-hydraulic characteristics at the plant operating conditions in this section.

FASTVIB2, a Westinghouse proprietary finite-element-based computer code, is written to [

]a.c,e. The Byron and Braidwood Unit 2 Model D5 lower tube support arrangement is illustrated in Figure 4-1. Note that the dimensions in Figure 4-1 are at the center of the tube supports.

Besides the thermal-hydraulic input to the F ASTVIB2 computer code, other inputs include: [

The F ASTVIB2 calculations for the turbulent displacement and frequency are based on 4.1.1 Boundary Conditions The boundary conditions include [

SG-SGMP-17-25-NP June 2020 Revision 1 Page 36 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3

] a,c,e.

4.1.2 Turbulence Displacement Secondary flow turbulence throughout the bundle produces

]a,c,e.

4.1.3 Damping in the Straight Leg Calculation of tube vibration response for each flow-induced mechanism requires use of [

]a,c,e SG-SGMP-17-25-NP June 2020 Revision 1 Page 37 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3

] a,c,e. Therefore, the referenced correlation for total damping is considered [

Ja,c,e.

4.2 Identification and Evaluation of Limiting Tube Locations A comprehensive review of the FIV parameters for tube locations across the steam generator tube bundle was made. The zone maps in Section 5 illustrate the [

Ja,c,e discussed in Section 3.

4.3 Significant Assumptions Significant assumptions used in the FIV evaluation of the Byron Unit 2 and Braidwood Unit 2 Model DS tube bundles are as follows .

.[

Ja,c,e.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 38 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 4.4 Design Input The Byron Unit 2 and Braidwood Unit 2 Model D5 steam generator tube bundles are comprised of

] a,c,e. These tubes are supported by the tubesheet, tube support plates, and anti-vibration bars.

Figure 4-1 shows details of the steam generator lower tube support arrangement.

The steam generator has [

Ja,c,e.

Other inputs to the F ASTVIB2 computer code are:

4.5 Summary of Results For these analyzed tube locations, both the straight leg (SL) modes on the hot and cold sides are analyzed and the governing results in terms of contribution to the wear model are presented in Table 4-1. This table contains the FIV input data for the limiting tube locations that provided [

One observation from the results in Table 4-1 is that two tubes in relatively close proximity can have significantly different vibrational characteristics. For example, tube locations [

SG-SGMP-17-25-NP June 2020 Revision 1 Page 39 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 4-1. Byron Unit 2 and Braidwood Unit 2 Analyzed Limiting Tube Locations - FIV Summary Cold Leg Max. Turb.

Frequency' Max.

Row Column Amplitude' (Hz) Node (inches) a,c,e

~ --

~ --

t-- --

t-- f- t--

t--

t--

t-- - --

t-- f-t-- - --

Hot Leg Max. Turb.

Frequency' Max.

Row Column Amplitude' (Hz) Node (inches) a,c,e

-t--

t-- - f- -

t-- f-t--

t-- - --

t-- - f- -

t-- - f- -

t-- - - - - -

Note 1: The results indicated are the maximum displacement and corresponding natural frequency anywhere along the straight leg region of that tube.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 40 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 a,c,e Figure 4-1. Byron Unit 2 and Braidwood Unit 2 Model D5 Steam Generators - Lower Tube Support Geometry (Dimension units in inches)

SG-SGMP-17-25-NP June 2020 Revision 1 Page 41of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 5 Screening Calculations and Zone Map Development (Pre-Outage) 5.1 High Flow Regions in the Tube Bundle In preparation for an outage at Byron Unit 2 and Braidwood Unit 2 where FOSAR is to be performed, one of the most important activities is to define the regions in the tube bundle that are susceptible to tube degradation from potential loose parts. The Byron Unit 2 and Braidwood Unit 2 SGs are a square pitch design with a preheater region on the cold leg side. In this design, the feedwater flow enters the preheater region and is directed towards the TSP 02C (Baffle Plate "B") within the preheater. The flow traverses upward and across the series of baffle plates where it exits the preheater box to mix with the bulk secondary water flow . The flow onto the tubesheet is primarily from fluid recirculation entering through the downcomer and flow through the auxiliary feedwater nozzle (approximately [ ] a,c,e of main feedwater flow). Only a small portion of the tubesheet fluid flow originates from the preheater. The regions of high flow relative to the remainder of the tube bundle at the specified elevation are defined by the red regions depicted in Figures 5-1 through 5-5. If possible, the entirety of the high flow regions should be considered in the FOSAR and eddy current inspection scope planning.

It is also noteworthy that the square pitch design usually results in the highest flow rates extending

]a,c,e. Figures 5-1 , 5-2 and 5-5 illustrate this phenomenon at the hot and cold leg TTS and Preheater B-Plate regions. In the square pitch design of the Model D5 SGs there is a tube-to-tube gap of approximately [ ] a,c,e inch. As a result, there [

5.2 Screening Calculations Based on the specific categories of foreign objects defined in Section 1, the maximum size of each type of part that would be expected to remain in the steam generator for the typical interval between tube inspections is then determined. Although the maximum size of a part will vary depending on the steam generator design, the most important consideration is the interval between tube inspections. When Byron Unit 2 and Braidwood Unit 2 are planning to skip SG inspection cycles (i.e. 2-cycle inspection interval or greater, up to a 4-cycle inspection interval), [

] a,c,e. Further, the Category 2 and 3 definitions as described in Section 6 and appearing in Table 5-1 through 5-5 correspond to specific wear time limits. Typically, Category 3 limiting object sizes have wear times that are [ ] a,c,e greater than the SG-SGMP-17-25-NP June 2020 Revision 1 Page 42 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 corresponding Category 2 limiting object sizes. The Category 3 objects are smaller in order to reach these longer wear times and represent a lower priority for retrieval.

Wear time calculations were performed to determine the acceptability of these objects for long-term steam generator operation. These calculations were performed for a typical set of foreign objects based on the general inventory of parts identified in Section 2 with the objects conservatively being elevated by deposits above TTS, FDB and Preheater B-Plate. Tables 5-1 through 5-5 contain the descriptions of a number of objects typically found in steam generators along with geometric dimensions associated with the various categories. This table also identifies the resulting category for use in the classification process, which is discussed in more detail in Section 6.

5.3 Zone Maps The earliest steam generator secondary side zone maps were based on [

Figures 5-1 through 5-5 show zone maps developed specifically for the Byron Unit 2 and Braidwood Unit 2 SGs based on gap velocity (V) at the hot leg and cold leg TTS, FDB and preheater B-Plate. In general, The following paragraphs describe how the zone maps were developed and how they can be used to help categorize foreign objects when used in combination with the foreign object classification strategy described in Section 6.

As an example, for two operating cycles, calculations were performed to determine the wear time for the

) a,c,e SG-SGMP-17-25-NP June 2020 Revision 1 Page 43 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Category 1, 2, and 3 classifications are according to the category definitions in Reference 4 and further discussed in Section 6. Similar calculations were made for the objects shown in Tables 5-1 through 5-5 to determine the appropriate size limit for Category I, 2 and 3 loose parts for two (2), three (3), or four (4) operating intervals between inspections.

The calculations performed to determine the foreign object sizes in Tables 5-1 and 5-2 were based [

It should be noted that these calculations assume the parts have a specific orientation with respect to the tube and are on the top of the tubesheet, FDB or Preheater B-Plate of the Byron Unit 2 and Braidwood Unit 2 SGs, which have a specific set of operating conditions. Therefore, these maps [

SG-SGMP-17-25-NP June 2020 Revision 1 Page 44 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 5-1. Limiting Foreign Objects Sizes at the HL TTS and B-Plate High Flow Zone for Two-, Three-, and Four-Cycle SG Inspection Intervals 2 Operating Cycles 3 Operating Cycles 4 Operating Cycles Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch)

Object Description for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Part ace Wires S [ ] a,c,e OD Wires > r ]3,c,e OD and s r ] a,c,e OD Gaskets Hard Sludge/Scale Machine Turnings Weld Slag Weld Rods/Nails Metal Objects/Strips/

Bushings/Washers/Nuts Weld Bead/Balls/Spheres Screws

a. Or any size if soft or crumbles.

SG-SGMP-1 7-25-NP June 2020 Revision I Page 45 of 63

  • This record was final approved on 6/16/2020 4 :07:08 PM . (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 5-2. Limiting Foreign Objects Sizes at the CL TTS High Flow Zone for Two-, Three-, and Four-Cycle SG Inspection Intervals 2 Operating Cycles 3 Operating Cycles 4 Operating Cycles Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch)

Object Description for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Par! c e Wires :S [ J a,c,e OD Wires > r J a,c,e OD and:::: r ] a,c,e OD Gaskets Hard Sludge/Scale Mach ine Turnings Weld Slag Weld Rods/Nails Metal Objects/Strips/

Bushings/Washers/Nuts Weld Bead/Balls/Spheres Screws

a. Or any size if soft or crumbles.

SG-SGMP-1 7-25 -NP June 2020 Revision I Page 46 of63

      • This record was final approved on 6/16/2020 4:07:08 PM . (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 5-3. Limiting Foreign Objects Sizes at the HL TTS and B-Plate Transition and Low Flow Zone for Two-, Three-, and Four-Cycle SG Inspection Intervals 2 Operating Cycles 3 Operating Cycles 4 Operating Cycles Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch)

Object Description for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Part a,c,e Wires S [ ]",c,e OD Wires > r ]'*'*' OD and < r l a,c,e OD Gaskets Hard Sludge/Scale Machine Turnings Weld Slag Weld Rods/Nails Metal Obj ects/Strips/

Bushings/Washers/Nuts Weld Bead/Balls/Spheres Screws

a. Or any size if soft or crumbles.

SG-SGMP-1 7-25-NP June 2020 Revision I Page 47 of 63

  • This record was final approved on 6/16/2020 4 :07:08 PM . (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 5-4. Limiting Foreign Objects Sizes at the CL TTS Transition and Low Flow Zone for Two-, Three-, and Four-Cycle SG Inspection Intervals 2 Operating Cycles 3 Operating Cycles 4 Operating Cycles Object Description Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Par1 c e Wiress [ ] a,c,e OD Wires > r ] a,c,e OD andsr l a,c,e OD Gaskets Hard Sludge/Scale Machine Turnings Weld Slag Weld Rods/Nails Metal Objects/Strips/

Bushings/Washers/Nuts Weld Bead/Balls/Spheres Screws

a. Or any size if soft or crumbles.

SG-SGMP-17-25-NP June 2020 Revision I Page 48 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 5-5. Limiting Foreign Objects Sizes at the FDB Transition and Low Flow Zone for Two-, Three-, and Four-Cycle SG Inspection Intervals 2 Operating Cycles 3 Operating Cycles 4 Operating Cycles Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch) Max. Dimensions (inch)

Object Description for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Part for a Category 2 Part for a Category 3 Part a ce Wires :::: [ ]a,c,e oD Wires > r Ja,c,e OD and < r la,c,e OD Gaskets Hard Sludge/Scale Machine Turnings Weld Slag Weld Rods/Nails Metal Objects/Strips/

B ushimi:s/Washers/Nuts Weld Bead/Balls/Spheres Screws

a. Or any si ze if soft or crumbles.

SG-SGMP-1 7-25-NP June 2020 Revision I Page 49 of63

  • This record was final approved on 6/16/2020 4 :07:08 PM . (This statement was added by the PRIME system upon its validation)

WESTLNGHOUSE NON -PROPRIETARY CLASS 3 a,c,e Figure 5-1. Secondary Side Fluid Gap Velocities above the Hot Side Tubesheet SG-SGMP- 17-25-N P June 2020 Revision I Page 50 of 63

      • This record was final approved on 6/16/2020 4:07 :08 PM . (This statement was added by the PRIME system upon its validation)

WESTLNGHOUSE NON -PROPRIETARY CLASS 3 a,c,e Figure 5-2. Secondary Side Fluid Gap Velocities above the Cold Side Tubesheet SG-SGMP- 17-25-N P June 2020 Revision I Page 5 1 of63

      • This record was final approved on 6/16/2020 4:07:08 PM . (This statement was added by the PRIME system upon its validation)

WESTLNGHOUSE NON -PROPRIETARY CLASS 3 a,c,e Figure 5-3. Secondary Side Fluid Gap Velocities above the Hot Side FDB (Plate A)

SG-SGMP- 17-25-N P June 2020 Revision I Page 52 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM . (This statement was added by the PRIME system upon its validation)

WESTLNGHOUSE NON -PROPRIETARY CLASS 3 a,c,e Figure 5-4. Secondary Side Fluid Gap Velocities above the Cold Side FDB (Plate A)

SG-SGMP- 17-25-N P June 2020 Revision I Page 53 of 63

      • This record was final approved on 6/16/2020 4:07 :08 PM . (This statement was added by the PRIME system upon its validation)

WESTLNGHOUSE NON -PROPRIETARY CLASS 3 a,c,e Figure 5-5. Secondary Side Fluid Gap Velocities above the Prehea ter TSP B-Plate SG-SGMP- 17-25-N P June 2020 Revision I Page 54 of 63

      • This record was final approved on 6/16/2020 4:07 :08 PM . (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6 Foreign Object Classification Process (during Outage) 6.1 General Categories With respect to Category 1 objects, [

] a,c,e.

These objects are described in Section 6.2.

It should be noted that in some instances objects found in the secondary side of steam generators do not fit into an exact shape or category as described in Tables 5-1 through 5-5. In those cases, some amount of experience-based judgment must be used. The location of the object in relation to the flow, the orientation of the part, and relative location in the tube bundle can mitigate or exacerbate the potential for tube wear. All these factors must be considered when assigning priorities to a specific loose part.

6.2 Default Category 1 Foreign Objects One of the methods used to quickly identify objects that should be removed is based on defining specific objects that have been known to produce leakage events in other steam generators and objects that are known or have the potential to be aggressive in nature. This includes definition of parameters as described in Section 1. The following is a definition of the types of objects that should be removed based on these criteria .

. [

]a,c,e.

The above are meant to be general criteria that may be used to quickly address a large number of objects.

It is not meant to be an all-inclusive list since it is not possible to know the exact inventory of objects that will be found during an outage. If it is not possible to remove the object, then a detailed analysis should be performed for that particular object using all available plant-specific data. Alternatively, a plugging and stabilization plan could be developed that would address the potential for excessive wear on tubes that could be affected by the object.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 55 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Two examples of small foreign objects that are known to have caused leaks are shown in Figures 6-1 and 6-2. These objects were found wedged between the tubes near the top of the tubesheet of two different triangular pitch SGs. The foreign object shown in Figure 6-1 weighed approximately

] a,c,e grams or less than [ ] a,c,e ounces. It was removed from the cold leg side of the tubesheet and measured approximately [ ] a,c,e inches long, [ ] a,c,e inch wide and [ ] a,c,e inch thick. It had an elemental composition consistent with low alloy steel. Three (3) tubes that were in contact with the foreign object had wear indications and one (1) tube had a through-wall wear scar.

The foreign object shown in Figure 6-2 weighed approximately [ ] a,c,e grams, which is also less than

] a,c,e ounce. It was removed from the hot leg side of the tubesheet and measured approximately

]a,c,e inch long, [ ]a,c,e inch wide and [ ] a,c,e inch thick. Its elemental composition was consistent with plain carbon steel that had been heavily cold-worked. This foreign object was also in contact with three (3) tubes; two (2) had wear scars greater than [ ] a,c,e through-wall while the thfrd tube had a through-wall wear scar.

It is interesting to note that the foreign object shown in Figure 6-2 was found in a relatively high flow region of the tube bundle but it was not in a foreign object "exclusion zone" which exists in some SG designs where no foreign objects are acceptable to remain in the secondary side. Both of these parts are good examples of Category 1 foreign objects that should be removed regardless of where they are located in the tube bundle.

6.3 Classification Process The following process will assist in determining which objects should be removed first from the steam generators once found during FOSAR. From the inventory of loose objects described in Section 2, it was possible to group most of the objects into ten (10) general classifications which can be found in Tables 5-1 through 5-5. The objective of the classifications was to identify the size and type of object that would be expected to be acceptable for up to two (2), three (3), or four (4) operational cycles. Objects that could potentially result in significant wear over long-term operation, even though analysis would be expected to demonstrate acceptability for two (2), three (3), or four (4) operational cycles, are considered to be

] a,c,e. See the table below for the general relationship between wear time and Category for each operating period:

SG-SGMP-17-25-NP June 2020 Revision 1 Page 56 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Operating Duration Category 2 Category 3*

a,c,e 2 Operating Cycles 3 Operating Cycles 4 Operating Cycles Note: The Category 3 wear times listed above [

] a,c,e.

Due to the longer wear times, [

] a,c,e.

The recommended process to be used during an outage includes the following steps:

SG-SGMP-17-25-NP June 2020 Revision 1 Page 57 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 The above process can be used as a guide to assist in the retrieval process. Note that there may be instances during the removal process where Category 1 objects are located near Category 2 or 3 objects.

In these cases, it might be practical to remove the Category 2 or 3 objects at the same time. Some flexibility in the removal process must be maintained.

It should also be noted that if an object is classified as "Category 1" it does not necessarily mean that the object [

]a,c,e .

6.4 Method Summary The best scenario with respect to foreign objects is that there would not be any foreign materials present inside the steam generators. However, it is recognized that safety, time and dose concerns can influence retrieval efforts, and in many cases it can be more appropriate not to remove objects that do not pose a significant potential for tube wear. The categories described in Tables 5-1 through 5-5 and Section 6.2 will assist in identifying which objects should be removed, while others would likely be found to be acceptable for a given period of operation. The process described is judged a reasonable method to help prioritize retrieval efforts for the most common types of objects found inside the secondary side of the Byron Unit 2 and Braidwood Unit 2 SGs.

6.5 Non-Metallic Objects The inventory of foreign objects found within the Byron Unit 2 and Braidwood Unit 2 SGs include a small number of non-metallic objects in form of cloth fiber, duct tape, and closure gasket winding filler material (i.e., graphite). These types of objects are soft and pliable [

]a,c,e. It is suggested that efforts be made during the inspection and/or retrieval process to convincingly determine whether or not an object is non-metallic. Further, a review for chemical compatibility with SG component materials should be performed of any potentially deleterious non-metallic materials to confirm that no deleterious chemical effects are encountered. This may require retrieval of a sample in order to evaluate the non-metallic substance being observed.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 58 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6.6 Recommended Eddy Current Inspection for Foreign Object Interaction Eddy current examination in targeted regions of a SG is an effective strategy to identify foreign objects and tube wear associated with foreign objects, especially when coupled with a robust visual inspection program. During a routine eddy current inspection several types of probe designs are typically used; a bobbin probe, a +POINT probe, and/or an array probe. A bobbin probe provides good detection of foreign objects and foreign object wear within the freespan portion of a tube, however, tube geometry changes, such as at or near the tubesheet expansion, hinders its detection capabilities. Use of the +POINT probe or array probe provides increased foreign object and foreign object wear detection capabilities at or near expansion transitions. For this reason many utilities frequently perform targeted +POINT probe or array probe inspection in areas that are susceptible to foreign object and wear due to foreign objects.

] a,c,e, a common industry practice is to inspect the top of tubesheet periphery tubes with a +POINT probe or array probe. [

Ja,c,e. However, this inspection may not include all the tubes that are susceptible to accelerated tube wear and, further, it may include tubes that are not susceptible to tube wear. This can create an inefficient inspection program which may or may not include the entire region considered potentially susceptible. The results of the analysis presented can be used to select an efficient eddy current inspection program in critical areas susceptible to collecting foreign objects and wear due to foreign objects.

Figures 5-1 through 5-5 provides tubesheet maps of the secondary side fluid gap velocities at the top of the tubesheet, FDB, and TSP 02C (or 'B-Plate' ) elevations. As discussed in prior sections, [

Ja,c,e. The tubes identified in red highlighting on Figures 5-1 through 5-5 indicate the tubes that experience [

For the hot leg tubesheet region (Figure 5-1 ), the areas of [

Ja,c,e. It is recommended that the hot leg periphery tubes highlighted in red on Figure 5-1 be inspected with the

+POINT probe or array probe from the FDB to a nominal distance into the tubesheet during routine SG inspection outages.

For the cold leg tubesheet region (Figure 5-2), the areas of [

Ja,c,e. The vast majority of the remaining SG-SGMP-17-25-NP June 2020 Revision 1 Page 59 of 63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 peripheral tubes, excluding the [

] a,c,e. The tubes along the periphery are susceptible to trap or collect foreign material, thus making identification of foreign material along the periphery advantageous to a robust foreign object mitigation program. Therefore, it is recommended that [

] a,c,e.

As shown on Figure 5-3 and Figure 5-4, no tubes have [

] a,c,e.

Figure 5-5 shows the tubes at TSP 02C (the 'B-Plate') that have [

] a,c,e. It is recommended that all tubes highlighted in red on Figure 5-5 be inspected with the bobbin coil probe during routine SG inspection outages.

SG-SGMP-17-25-NP June 2020 Revision 1 Page 60 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Figure 6-1. Example of a Foreign Object that Resulted in a Tube Leak - Sample 1 SG-SGMP-17-25-NP June 2020 Revision 1 Page 61of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Figure 6-2. Example of a Foreign Object that Resulted in a Tube Leak - Sample 2 SG-SGMP-17-25-NP June 2020 Revision 1 Page 62 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 7 References

1. Westinghouse Calculation Note CN-SGMP-17-5 , Rev. 1, "Analysis of Loose Parts in the Byron Unit 2 and Braidwood Unit 2 Steam Generators," June 2020. (Westinghouse Proprietary Class 2)
2. M . J. Pettigrew, R. J. Rogers, and F . Axisa, "Damping of Multispan Heat Exchanger Tubes: Part 2 In Liquids," ASME PVP Publication Vol. 104, Chicago, IL, July 1986, pg. 89-98.
3. Westinghouse Research Laboratories Report 73-1E7-FLVIR-R2, "Flow-Induced Vibration of Rod Bundles in Axial Flow. II - Hydrodynamic Damping and Added Mass," December 1973.

(Westinghouse Proprietary Class 2)

4. EPRI Report 1019039, "Steam Generator Management Program: Foreign Object Prioritization Strategy for Square Pitch Steam Generators," May 2009.
5. EPRI Report EPRI-NP-4604-CCML, Singhal, A. K. , et al. , "ATHOS3 Mod 01: A Computer Program for Thermal Hydraulic Analysis of Steam Generators, Volumes 1-3," September 1990.
6. Westinghouse Calculation Note CN-SGMP-17-1 , Revision 1, "Byron Unit 2 and Braidwood Unit 2 Steam Generator Tube Structural Limits," September 2017. (Westinghouse Proprietary Class 2)
7. EPRI Report 3002007571 , Revision 4, Steam Generator Management Program: Steam Generator Integrity Assessment Guidelines," June 2016.
8. Westinghouse Report WNEP-8382, Rev. 1, "Model D5 Steam Generator Thermal and Hydraulic Design Data Report for Commonwealth Edison Company Byron Unit 2 (CBE)," March 1988.

(Westinghouse Proprietary Class 2)

9. Westinghouse Report WTD-TH-79-021 , Rev. 2, "Model D5 Steam Generator Thermal and Hydraulic Design Data Report for Commonwealth Edison Company Braidwood Unit 2 (CDE)," March 1988.

(Westinghouse Proprietary Class 2)

10. Westinghouse Calculation Note CN-NCE-10-3 , Rev. 0, "Thermal-Hydraulic Evaluations of the Byron and Braidwood Units 2 Steam Generators to Support the 3672 MWt NSSS MUR Uprate Program,"

July 2010. (Westinghouse Proprietary Class 2)

11. Westinghouse Letter PCWG-09-47, Rev. 0, "Byron and Braidwood Units 1 & 2 (CAE/CCE/CBE/CDE): Approval of Category IIIP (for Limited Scope Contract) and Category III (for Full Scope Contract) PCWG Parameters to Support the MUR Uprate Program," November 2009.

(Westinghouse Proprietary Class 2)

12. Westinghouse Calculation Note CN-SGMP-14-8, Rev. 0, "Thermal-Hydraulic Analysis for the Generic U-bend Tube Fatigue Analysis of the Model D5 Steam Generators with Tube Support Plate Clogging," November 2014. (Westinghouse Proprietary Class 2)

SG-SGMP-17-25-NP June 2020 Revision 1 Page 63 of63

      • This record was final approved on 6/16/2020 4:07:08 PM. (This statement was added by the PRIME system upon its validation)
Retrieved from "https://kanterella.com/w/index.php?title=ML20195B162&oldid=2921664"