LG-25-065, Owners Activity Report (OAR-1) for LI1R20, Dated July 24, 2024

Owners Activity Report (OAR-1) for LI1R20, Dated July 24, 2024

ML25101A148
Person / Time
Site:	Limerick
Issue date:	04/08/2025
From:	Gillin M Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, NRC Region 1, Document Control Desk
Shared Package
ML24206A250	List: LG-24-089, Owners Activity Report (OAR-1) for Li1R20 LG-25-065, Owners Activity Report (OAR-1) for LI1R20, Dated July 24, 2024
References
LG-25-065
Download: ML25101A148 (1)

Text

LG-25-065 April 8, 2025 Constellation USNRC Region I, Regional Administrator U.S. Nuclear Regulatory Commission, Region I 475 Allendale Road, Suite 102 King of Prussia, PA 19406-1415 Limerick Generating Station, Unit 1 Renewed Facility Operating License Nos. NPF-39 NRC Docket Nos. 50-352 ASM E Section XI

Subject:

Limerick Generating Station Unit 1 Owner's Activity Report (OAR-1) Supplement for Li1 R20

Reference:

LG-24-089, Limerick Generating Station Unit 1 Owner's Activity Report (OAR-1) for Li1 R20, dated July 24, 2024 The Limerick Generating Station Unit 1 OAR-1 for Li1 R20 was submitted in accordance with ASME Section XI Article IWA-6200, and ASME Section XI Code Case N-532-5. This report included inspections and repair and replacement activities completed during the third Period of the Fourth lnservice Inspection Interval and the Third Containment lnservice Inspection Interval.

During a review of the documentation submitted, the station identified that one of the attachments, EC 641238, Rev. O, 1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges, had inadvertently been omitted from the letter transmitted to the NRC. That document is attached to this letter. The station has entered the omission in its Corrective Action Program, Issue Report 4847261.

There are no regulatory commitments contained in this letter.

If you have any questions or require additional information, please contact Marcellus Ruff at 610-718-3530.

Respectfully, Michael F. Gillin Site Vice President, Limerick Generating Station Constellation Energy Generation, LLC

Attachment:

EC 641238, Rev. 0, 1 R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges

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1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 1 of 9 DOCUMENT NO.: EC 0000641238 TITLE: 1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges PREFACE:

This Technical Evaluation is performed in accordance with CC-AA-309-101, Rev. 16. The Limerick suppression pool is safety related; therefore, an Independent Review will be performed. A Pre-Job Brief and Technical Task Risk/Rigor Assessment was performed for this evaluation in accordance with HU-AA-1212, Rev. 13. This review identified a Risk Rank of 1 (existing process reviews), based on a Low Consequence Risk Factor and a Low Probability of Error.

REASON FOR EVALUATION / SCOPE During refueling outage 1R20, a visual examination of 100% of the submerged portion of the suppression pool liner was performed as required by License Renewal Commitment 30 (Reference 4), ASME Section XI, and the Limerick coating maintenance program. Visual examinations are performed in accordance with ASME Section XI, 2007 Edition through 2008 Addenda (Reference 1), Subsection IWE, Requirements for Class MC Metallic Liners of Class CC Components in Light-Water Cooled Plants.

License Renewal Commitment 30 requires removal of any accumulated sludge in the suppression pool every refueling outage. During desludging of the suppression pool in preparation for visual inspections, bubbles were identified coming from a leak chase channel near the m tee-quencher which is indicative of a small hole in the leak chase channel, see Issue Report 4765433 (Reference 6). Subsequent examination confirmed the presence of a small (approx. 3/64 inch diameter) hole in the top of the inner leak chase channel in the northwest corner of the m tee-quencher. This condition allows suppression pool water to fill the leak chase channel and will lead to corrosion of the underlying liner plate and weld.

This technical evaluation will evaluate the impact to the underlying liner plate and weld and demonstrate the acceptability of the condition until 1R22 (2028), at which time the next 100% inspection of the submerged space of the suppression pool liner is required in accordance with License Renewal Commitment 30.

Since this condition can result in degradation of the inaccessible containment liner beneath the leak chase channel, this technical evaluation will also address the requirements of ASME Section XI, Subsection IWE-2500(d), ER-AA-330-007 (Reference 2), and 10 CFR 50.55a (Reference 3).

ASME Section XI, Subsection IWE-2500(d) requires an engineering evaluation to be performed to determine the acceptability of inaccessible areas when conditions exist in accessible areas that could indicate the presence of or result in degradation in an inaccessible area. In accordance with 10 CFR 50.55a(b)(2)(ix)(A)(2):

For each inaccessible area identified for evaluation, the applicant or licensee must provide the following in the ISI Summary Report as required by IWA-6000:

i.

A description of the type and estimated extent of degradation, and the conditions that led to the degradation; ii.

An evaluation of each area, and the results of the evaluation; and iii.

A description of necessary corrective actions.

Additionally, during the 1R20 visual examinations of the submerged suppression pool liner, two bulges were identified and documented in IR 4766104 and 4766238 (Reference 12 and 13). These bulges were small areas of the liner plate that were reported to be raised upward from the surrounding wall/floor plate.

This technical evaluation will also provide a disposition of the two bulges reported during the visual examinations in the Limerick Unit 1 suppression pool.

1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 2 of 9 DETAILED EVALUATION 1R20 suppression pool dive activities were performed per work order 5265579 (Reference 5). The scope of work included desludging the entire suppression pool and visual examination of 100% of the submerged, accessible areas of the suppression pool as required by License Renewal Commitment 30.

Additionally, the 1D1-F211 and 1D2-F211 RHR strainers were removed from the penetrations so the inaccessible areas behind and beneath the strainers could be inspected and recoated. The visual examinations of the suppression pool liner were performed in accordance with ASME Section XI, 2007 Edition with the 2008 Addenda, Subsection IWE.

During desludging of the suppression pool, in preparation for visual inspections, bubbles were identified coming from a leak chase channel near the m tee-quencher which is indicative of a small hole in the leak chase channel. Subsequent examination confirmed the presence of a small (approx. 3/64 inch diameter) hole in the top of the inner leak chase channel in the northwest corner of the m tee-quencher, see Issue Report 4765433. Figure 1, below, shows the location and a photo of the hole in the m tee-quencher leak chase. The presence of a hole in the leak chase channel allows for suppression pool water to fill the volume of the leak chase and come in contact with the underlying containment liner plate and weld. Suppression pool water in contact with the uncoated containment liner plate and weld will result in corrosion of these materials. Visual examination of 100% of the accessible suppression pool surfaces, including all leak chase channels, was completed in 1R20 and no similar conditions were identified on other leak chase channels.

Figure 1 - location and photo of approx. 3/64 hole in m tee-quencher leak chase

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1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 3 of 9 The area inside of the leak chase channel is considered an inaccessible area in accordance with ASME Section XI, Subsection IWE. As required by IWE-2500(d) this evaluation will document the acceptability of the inaccessible area and address the additional requirements of 10 CFR 50.55a.

Additionally, during the 1R20 visual examinations of the submerged suppression pool liner, two bulges were identified. These bulges were small areas of the liner plate that were reported to be raised upward from the surrounding wall/floor plates. These two areas are also dispositioned in this evaluation.

Design Attributes The suppression pool is designed to have a metal liner supported by concrete. The metal liner serves as a membrane pressure barrier that functions to increase the containment integrity by retaining gasses and water within the containment during normal and accident conditions. The suppression pool liner is made up of 1/4 inch (250 mils) ASTM A 285 carbon steel plates welded together as shown on drawing C-281 (Reference 8) and Specification C-002 (Reference 9). A leak chase channel system is provided on the liner plate seam welds under water in the suppression pool as shown on drawing C-281. Following installation, the leak chase system was pressurized to 72 psig to verify the leak tightness of the underlying liner plate welds and leak chase system attachment welds.

As shown on drawing C-263 (Reference 7), the m tee-quencher is located at the 258 degree azimuth of the suppression pool. The configuration of the tee-quencher support base plate leak chase channels are shown in Detail 1, Detail 2, and Section B of drawing C-263. Each tee-quencher support base plate is a 3-1/2 inch thick, SA-516, Grade 70 carbon steel plate installed by cutting back the existing liner plate and tapering the base plate as shown in Section B of drawing C-263. Following welding of the tee-quencher support base plates to the existing liner, leak chase channels were installed with a 3/16 inch fillet weld and pressure tested to verify the leak tightness of the underlying welds and the leak chase attachment welds. Upon completion of testing, the test couplings were plugged and seal welded to prevent intrusion of suppression pool water into the leak chase channels during operation.

Following fabrication and testing of the suppression pool liner, an inorganic zinc coating was applied to protect the liner and leak chase channels from corrosion. The zinc coating protects the metal surface because the zinc preferentially sacrifices itself to the corrosion. As the zinc dissipates, the amount of protection of the metal liner decreases, and once the zinc is completely depleted, the protection stops. A number of locations in the Limerick Unit 1 suppression pool have completely depleted the zinc coating.

With the loss of the protective coating, some areas on the liner plates and leak chase channels have started to corrode.

An evaluation of the corrosion of the Limerick suppression pool was performed by Structural Integrity Associates, titled "Corrosion Evaluation of the Limerick Mark II Containment (Reference 10). This evaluation determined the corrosion occurring in the Limerick suppression pool is general corrosion (rust),

and not the more aggressive pitting corrosion damage mechanism. This corrosion can be over large areas (general corrosion) or localized over a smaller area (spot corrosion).

The Limerick acceptance criteria for corrosion are contained in Section 5.2.4 of Limerick Specification NE-101 (Reference 11) and provided below for reference.

x The acceptance criteria for general corrosion (areas greater than 12.5 inches in diameter) is 125 mils metal loss or an average of 125 mils remaining liner material.

x The acceptance criteria for local areas of general corrosion (areas less than or equal to 2.5 inches in diameter) or spot corrosion is 187.5 mils metal loss or 62.5 mils remaining liner material.

At the time of construction, the design thickness of the suppression pool plates was 1/4 inch (250 mils).

The suppression pool liner plate material specification (ASTM A285) references ASTM A20 (Reference 15), General Requirements for Steel Plates for Pressure Vessels, which provides the permissible variations in thickness for steel plates ordered to thickness. The metal loss values given for the

1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 4 of 9 acceptance criteria above assume the plates had an initial thickness of 250 mils at the time of construction.

To verify the as installed thickness of the suppression pool liner plates, License Commitment 30 requires ultrasonic thickness measurements of non-degraded areas during each inspection period. These inspections have demonstrated that non-degraded areas of the suppression pool liner plates remain very close to if not above the initial minimum wall thickness of 250 mils following approximately 40 years of service. During 1R20, four plates had ultrasonic thickness measurements taken to satisfy the requirements of License Renewal Commitment 30. The 1R20 thickness readings of sound (non-degraded) areas ranged from a low of 243 mils to a high of 280 mils (Attachment 2).

Description of Degradation The corrosion identified in the Limerick Unit 1 suppression pool is categorized as general corrosion, localized general corrosion or tiger striping. A description of each type of corrosion is provided below.

x General Corrosion: Also known as uniform corrosion. This term refers to corrosion that completely covers a surface of more than several square inches. Metal loss is generally uniform across the exposed area and typically does not involve much section loss.

x Localized General Corrosion (Spot Corrosion): Spot corrosion is simply general corrosion that presents itself as localized spots of exposed substrate on a coated surface. Spots are generally less than a few square inches each but may be up to several square inches. Metal loss is generally uniform across each exposed area and typically does not involve much section loss.

Spot corrosion should not be confused with pitting corrosion which is a highly localized and accelerated degradation of base metal typically in the presence of an aggressive anion such as chlorine.

x Tiger Striping: Relative to coatings in immersion service, tiger striping is a condition unique to inorganic zinc-rich coatings. It is a coating condition that is found on vertical surfaces, typically in stagnant, underwater conditions. In the early stage, it appears in alternating vertical light and dark stripes within the coating itself. The light stripe usually acts as the cathode and the dark stripe as the anode. Over time, zinc in the anodic areas is depleted/consumed giving way to corrosion of the substrate. It is essentially general corrosion in dense vertically aligned corrosion nodules. Like general corrosion, associated metal loss is typically minor.

The corrosion rates of the Limerick Unit 1 suppression pool have been low. This is due to the inert atmosphere of the suppression pool during plant operations and the water quality of the suppression pool.

The corrosion of the submerged portion of the suppression pool liner has been trended using several corrosion evaluation grids. Four evaluation grids were established in 1996 with inspection of these areas performed between 1996 and 2016. The data obtained from these evaluation grids shows that the metal liner with no coating is experiencing an average general corrosion rate of approximately 1 to 2 mils per year which is in line with the calculated corrosion rate of 1.8 mils per year (Reference 10). The maximum corrosion rate between examinations for any single location over this inspection interval was 5.7 mils per year (Reference 14).

Following the 2016 refueling outage (1R16), all four evaluation grids were recoated due to many pits exceeding, or projecting to exceed, the applicable recoat criteria prior to the next refueling outage. In 1R17 (2018) two new pit grid evaluation areas were established to continue to trend liner plate thickness loss. These two new pit grids were inspected in 2018, 2022, and 2024 with an average wall loss of 1 to 2 mils per year consistent with the previous pit grids. The maximum corrosion rate between examinations for any single location for the new pit grid evaluation areas is 5.9 mils based on the 2024 examination data.

1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 5 of 9 1R20 Inspection Results and Evaluation During desludging of the suppression pool, in preparation for visual inspections, bubbles were identified coming from a leak chase channel near the m tee-quencher. Subsequent examination confirmed the presence of a small (approx. 3/64 inch diameter) hole in the top of the inner leak chase channel, see Issue Report 4765433. The leak chase channel is not the containment liner and performs no structural function. However, the presence of a hole in the leak chase channel allows for suppression pool water to come in contact with the underlying containment liner plate and weld and will lead to corrosion of these materials.

A corrosion evaluation is performed to demonstrate acceptance of this condition until the next required inspection in 1R22 (2028). Prior to the next required inspection, a plan will be developed to address the long term acceptance or repair of this condition, see ATI 4765433-04.

In accordance with License Renewal Commitment 30, a visual inspection of 100% of the submerged area of the suppression pool is required each inspection period. These examinations were most recently performed in 1R20 (2024), 1R19 (2022), and 1R16 (2016). A one-time exception to the inspection requirement was taken in 1R18 (2020) due to the COVID-19 pandemic. No previous inspection has identified degradation of the leak chase channels leading to a through wall leak. Since no examinations prior to 1R20 (2024) identified a through wall hole in the leak chase channels, the condition is assumed to have started between 1R19 (2022) and 1R20 (2024).

The corrosion rate of the submerged portion of the suppression pool liner is being trended and is between 1 to 2 mils per year based on pit grid data collected during ASME Section XI, IWE inspections performed between 1996 and 2022 (Reference 14). This measured corrosion rate is in line with the general corrosion rate of 1.8 mils per year calculated by an engineering analysis for uncoated carbon steel components in the suppression pool for the Limerick specific suppression pool water chemistry and operating temperature (Reference 10). Since the area inside the leak chase channel does not experience any flow, the potential exists for a more aggressive environment, with higher corrosion rates. Therefore, an additional factor will be applied to the corrosion rate used in the corrosion evaluation to account for this uncertainty.

To determine the expected corrosion prior to the next required inspection in 1R22 (2028), the condition is assumed to have started in 1R19 (2022) since the 100% visual examination was performed with no evidence of through wall indications in the leak chase channel system reported. Prior to 1R19, the underlying liner plate and weld were isolated from the suppression pool water and not subject to the general corrosion experienced by the rest of the suppression pool liner plate. Therefore, the initial plate thickness is assumed to be 250 mils based on the original design requirements as verified through ultrasonic thickness measurements each inspection period as required by License Renewal Commitment

30. Using the average corrosion rate in the Unit 1 suppression pool (1.7 mils), with an additional factor of 2 to account for the potentially more aggressive environment in the leak chase channel, the wall loss in 1R22 (2028) is expected to be:

(2 mils/year x 6 years) x 2 = 24 mils This corrosion results in an expected remaining wall thickness in 1R22 (2028) of:

250 mils - 24 mils = 226 mils To conservatively estimate the worst case corrosion, a second corrosion evaluation is performed using the highest measured corrosion rate in the Unit 1 suppression pool (5.9 mils per year). Using the worst case corrosion rate, with an additional factor of 2 to account for the potentially more aggressive environment in the leak chase channel, the worst case wall loss in 1R22 (2028) is expected to be:

(5.9 mils/year x 6 years) x 2 = 70.8 mils

1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 6 of 9 This corrosion results in a worst case expected remaining wall thickness in 1R22 (2028) of:

250 mils - 70.8 mils = 179.2 mils A remaining wall thickness of 179.2 mils has significant margin to the previously established metal repair criteria for general metal loss (125 mils metal loss or 125 mils remaining wall thickness) and local metal loss (187.5 mils metal loss or 62.5 mils remaining wall thickness).

Corrective Actions 1R20 is the first outage that a through wall condition has been identified on the leak chase channel at Limerick Unit 1 or Unit 2. Short term acceptance until the next required visual inspection of the suppression pool in 1R22 (2028) is documented in this evaluation. ATI 4765433-04 has been generated to drive a long term solution for inspection and repair of the liner plate under the leak chase channel.

Evaluation of Liner Plate Bulges During 1R20 inspections and large area recoating, two liner plate bulges were reported (Reference 12 and 13). These areas were described by the divers as areas where the plate had an upward deflection from the normal plane of the plate. The dimensions and location of the two bulges are provided in and 2 and summarized below.

An ultrasonic examination of each bulge was performed to assess the thickness of the suppression pool liner plate in these areas. Ultrasonic examination readings were obtained by having the diver position the UT probe per the direction of the certified inspector who interpreted the results. The tables below provide the results of the ultrasonic examinations for each bulge area.

Bulge #1 is located on wall plate 1-WP-05A. This wall plate is located in the normally inaccessible area behind the D RHR strainer. During 1R20, the D RHR strainer was removed from the penetration to allow for inspection and recoating of the normally inaccessible area behind and beneath the strainer. The UT thickness readings for 1-WP-05A were taken after the existing coating was removed and the liner plate was prepared for recoating. Therefore, the wall thickness values presented below are the liner plate metal thickness with no coating applied.

Bulge #1, (readings were taken as shown in Figure 2, below)

Wall Plate 1-WP-05A, Size 24 W x 40 H, max deflection 1 Grid A

B C

D Spot location 1

0.268 0.249 0.268 n/a BC1 0.269 2

0.271 0.244 (min) 0.275 0.271 CD1 0.272 3

0.277 0.274 0.276 0.270 AB2 0.250 4

0.256 0.278 0.275 0.274 BC2 0.272 5

0.273 0.279 (max) 0.275 0.256 AB3 0.275 AB4 0.274 Table 1 - UT Measurements for 1-WP-05A Bulge

1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 7 of 9 Figure 2 - UT Grid for 1-WP-05A Bulge Bulge #2 is located on floor plate 1-FP-03C in the annulus area adjacent to the suppression pool wall.

This location was previously recoated using the BioDur epoxy coating. Upon initial discovery of the bulge, coating dry film thickness readings were taken with the average coating thickness measuring between 12 mils to 16 mils, with some locations as high as 25 mils coating thickness. The UT thickness readings for 1-FP-03C were taken on the previously repaired liner plate, therefore, the wall thickness values presented below are the combined coating and liner plate metal thickness.

Bulge #2, (readings were taken as shown in Figure 3, below)

Floor Plate 1-FP-03C, Size 6.5 W x 14 H, max deflection 1/2 Grid A

B C

D E

1 0.322 0.302 0.328 0.338 0.300 2

0.320 0.323 0.314 0.331 0.299 (min) 3 0.309 0.323 0.322 0.317 0.335 4

0.329 0.331 0.324 0.339 0.315 5

0.325 0.303 0.328 0.347 (max) 0.329 6

0.312 0.317 0.317 0.315 0.315 7

0.326 0.309 0.299 (min) 0.323 0.332 Table 2 - UT Measurements for 1-FP-03C Bulge A

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1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 8 of 9 Figure 3 - UT Grid for 1-FP-03C Bulge The minimum wall thickness recorded on wall plate 1-WP-05A was 244 mils while the minimum wall thickness recorded on floor plate 1-FP-03C was 299 mils. Accounting for the maximum measured coating thickness (25 mils) on floor plate 1-FP-03C the metal thickness of the bulge is at least 274 mils.

The minimum wall thickness required for the suppression pool liner plates at the time of construction was 0.250 inches (250 mils). The minimum wall thickness required for structural integrity of the liner plate for general corrosion is 0.125 inches.

Based on the plate thickness measurements attained during 1R20, the surface bulges identified on wall plate 1-WP-05A and floor plate 1-FP-03C have significant margin available to all established repair criteria, are acceptable for continued service, and have no negative impact on the ability of the suppression pool liner plate to perform its intended function. These conditions do not appear to be service induced and are likely due to fit up and fabrication of the suppression pool liner during original construction.

CONCLUSIONS / FINDINGS Based on the information presented, and the conservative assumptions, the liner plate in the inaccessible area of the leak chase channel is acceptable for continued service. A corrosion evaluation was performed assuming the worst case corrosion rate experienced in the Limerick Unit 1 suppression pool, with an additional factor of 2 to account for the potentially more aggressive environment in the leak chase channel. This evaluation demonstrates that margin exists to all established repair criteria until the next required inspection in 1R22 (2028). ATI 4765433-04 has been generated to drive a long term solution for inspection and repair of the liner plate under the leak chase channel.

Based on the data gathered during 1R20 and a review of design information, the liner plate bulges identified on wall plate 1-WP-05A and floor plate 1-FP-03C will not impact the function of suppression pool liner due to the significant margin that is available to all established repair criteria and are therefore

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1R20 Evaluation of Degraded Leak Chase Channel and Suppression Pool Liner Plate Bulges EC 0000641238 Page 9 of 9 acceptable for continued service.

A 100% inspection of the submerged space of the suppression pool liner is required to be performed no later than 1R22 (2028) to satisfy the requirements of License Renewal Commitment 30. Reinspection of the conditions dispositioned in this evaluation will be performed at this time.

REFERENCES:

1. ASME Section XI 2007 Edition through 2008 Addenda

2. ER-AA-330-007, Visual Examination of Section XI Class MC Surfaces and Class CC Liners, Revision 15

3. 10CFR50.55a, Codes and standards

4. License Renewal Commitment A.2.1.30 (LRAT 1232104-47), ASME Section XI, Subsection IWE.

5. Work Order 5265579, Inspect Suppression Pool Coatings

6. IR 4765433, Bubbles Coming from Suppression Pool Leak Chase Channel

7. Drawing C-263, Reactor Building Units 1 & 2 Primary Containment Quencher Support Base Plates

8. Drawing C-281, Reactor Building Units 1 & 2 Liner Plate Requirements Floor Plan & Details

9. Specification C-002, Specification for Furnishing, Detailing, Fabricating, Delivering and Erecting the Primary Containment Liners for Limerick Generating Station, Units 1 & 2

10. Structural Integrity Associates Report 1101502.401,Corrosion Evaluation of the Limerick Mark II Containment, Revision 0 (IR 1364843-07)

11. Limerick Specification NE-101, Coating and Liner Inspection/Coating Repair of Suppression Chambers, Revision 8

12. IR 4766104, Li1R20 Bulge Found in Suppression Pool Liner Plate

13. IR 4766238, Li1R20 Bulge Found IN suppression Pool Liner Floor Plate

14. 1R19ISI6, Limerick 1R19 Suppression Chamber Project, April 2022

15. ASTM A20/A20M, Standard Specification for General Requirements for Steel Plates for Pressure Vessels ATTACHMENTS:

1. NDE Data Report LGS-1-24-UT-036, UT Erosion/Corrosion Examination Data Sheet 1-WP-05A (2 pages)

2. NDE Data Report LGS-1-24-UT-035, UT Erosion/Corrosion Examination Datasheet 1-FP-06D, 1-FP-08A, 1-WP-02A, 1-WP-08B, & 1-FP-03C (3 pages)

PREPARER:

Mark Weis Date: See Passport Milestones INDEPENDENT REVIEWER:

Anthony Haney Date: See Passport Milestones Independent Reviewer Comments:

I have performed an Independent Review of this technical evaluation per CC-AA-309-101. I have reviewed the reference documents and agree with the inputs. The outputs, conclusions, and actions are reasonable and well supported by the inspection results from 1R20. An Independent Review was performed by an individual qualified per N-AN-ENG-CERT-PG04 (ISI/CISI/Component Supports) who is familiar with the 10CFR50.55a requirements for evaluating inaccessible areas of the suppression pool.

Minor comments were made and have been incorporated.

Design Interface Review:

Mark Legutko Date: See Passport Milestones APPROVER:

Marcellus Ruff Date: See Passport Milestones

EC 0000641238 Attachment 1 Page 1 of 2 UT Erosion/Corrosion Examination

=-* Constellalion Outage No.: N/A Site/Unit: UM

/ 1 Procedure: ER-AA-335-004 Int/ Per: N/A Summary No.: BOP-040 Procedure Rev.: 9 Report No.: LGS-1-24-UT-036 Workscope: BOP-OUTAGE Work Order No.: 05265579-68 Page: 1 of 2 Code:

NLA cat./ltem:

N/ A Location:

.;.RX~R=O=O __ M __ 1=0=1=E;.;.I. =18;;;,;2;;;..' -------------

Drawing No.:

NLA

==

Description:==

SUPRESSION POOL WALL & FLOOR PLATES System ID:

060 Component ID:

10-S199 / WALL PLATE 1-WP-OSA Limitations:

None Csllbratfon Information Partitioning Information Component Information calibration Thickness (In) calibration limes / Initials Component Begin/Col/Row Ending/Col/Row Component Geometry:

CS Plate Actual Measured M. UPSTExt.

N/A N/A Outside Diameter:

N/A o.soo 0.500 Start:

1402 SM Main UPST.

N/A N/A Max. Thickness:

0.279" 0.400 0.400 Verify:

N/A N/A Main N/A N/A Min. Thickness:

0.244" 0.300 0.300 Verify:

N/A N/A Main DNST.

N/A N/A Nominal Thickness: N/ A 0.200 0.200 N/A M. ONST Ext.

N/A N/A Grid Size:

Various Tmin: N/A Verify:

N/A Branch N/A N/A Mln. Thlckness Locatfon:

82 0.100 0.100 Final:

1606 SM Branch Ext.

N/A N/A Max. Thickness Location:

BS Surface Condition:

Machined Instrument:

Transducer:

Reference/Simulator Block:

Temp. Tool:

Manufacturer: Olympus Manufacturer: Panametrics Serial No.: 18-2507 Manufacturer: _N_./_A _________ _

Model: 38 DL Plus Serial No.: 703091 Type: Step Wedge Serial No.: _N..,/_A __________ _

Serial No.: 140875305 Size:

o.s*

Freq:

5MHz Couplant*

G f. 61 dB Mod I*

0798 Ref./Slm. Block Temp.:

N/A

°F an.

e.

---

Material/Comp. Temp.:

NIA Of Couplant:

... u....

ttra___.9,._e_l _D ______ _

Range: 1.000

1. of Elements:

2 Batch No.: 21KO29 Comments UT on underwater suppression pool wall plate (1 *WP-OSA) per the direction of engineering. See supplemental page for grid layout and readings.

Results:

NRI Percent Of coverage Obtained > 90%:

Examiner Matthews! Shane M.

Examiner Level NLA Other N/A Level RI 1000/o Signature Signature IO [vi N/A Reviewed Previous Data:

Exam Date 04/13/2024 Exam Date Date IANII Re&ew C

' SianAtur}

• Date

'r-lS--

L\-lS,'Z.o Date Date

/

EC 0000641238 Attachment 1 Page 2 of 2

=" Constellation Summary No.:..:B:..:O:..:P_-...::0....:4...::0 __________

Examiner Matthews, Shane M. ~evel: IIL Examiner N/ A Level:

Other N/A Level:

Comments:

None A

1 0.2680 Supplemental Report Reviewer Site Review ANII Review B

C L£/Mv t:,h, al

~ri..l<JeMO

~

D 6"

- - ~~-.2_~~Q-0*- - - - *- Q..2680

'(:)'_;

BCl Sketch or Photo:

2 : 0.2710.'

j0.2440 C 2750 I

0.2710 I

I I

I 12" I

0 G

I I

I 3 ; 0.2170

!o ~7,10 0.2760 I

0.2702

, G I

I I

12" I

I 4 0.1560 0.2780 0.2760 0.2740 I

0

./

I I

I I

12" I

5 10.2730 i0.2790 1o.2750 10.256.o 12" 12**

16" Wall Plate 1-WP-05A Report No.: LGS-1-24-UT-036 Page: _2 __ _

of _2 __

Date: ___l).,,__-L:f,, l./

Date: <.( -I S'*Z!:J Date:

BCl 0.2690 CDl 0.2720 A82 0.2500 8(2 0.2720 A83 0.2750 A84 0.2740

EC 0000641238 Attachment 2 Page 1 of 3

-=- ConsteUat1on Site/Unit: LIM

/ __ 1 _____

Summary No.: _B...,cO __ P_-0-'-9'-3'---- -----

Workscope: BOP-OUTAGE Code:

NLA Drawing No.:

N/A System ID:

060 Component ID:

10-S199/SUPPRESSION POOL WALL PLATE Limitations:

None Calibration Information Calibration Thickness (In)

Calibration Times / Initials Actual Measured O.S00 O.S00 Start:

1408 SM 0.400 0.400 Verify:

N/A N/A 0.300 0.300 Verify:

N/A N/A 0.200 0.200 Verify:

N/A N/A 0.101) 0.100 Final:

1546 SM UT Erosion/Corrosion Examination Outage No.: N/A Procedure: ER-AA-335-004 Int/ Per: N/A Procedure Rev.: 10 Report No.: LGS-1-24-UT-035 Work Order No.: 05265579-68 Page: _L of 3 c.at./Item:

--N.._/A;..;_ ___ _____ _ _

Location:

RX ROOM 101 El. 182'

==

Description:==

SUPPRESSION POOL WALL AND FLOOR PLATE Partitioning Information Component Information Component Begin/Col/Row Ending/Col/Row Component Geometry:

CS Plated M. UPST Ext.

N/A N/A Outside Diameter: N/A Main UPST.

N/A N/A Max. Thickness:

0.347" Main N/A N/A Min. Thickness:

0.251" Main DNST.

N/A N/A Nominal Thickness: N/A M. DNST Ext.

N/A N/A Grid Size:

2.0" Tmin: N/A Branch N/A N/A Min. Thickness Location:

1-FP-06D Branch Ext.

N/A N/A Max. Thickness Location:

D5 Surface Condition:

Coating/Bare Metal Instrument:

Transducer:

Reference/Simulator Block:

Temp. Tool:

Manufacturer: Olympus Manufacturer: Panametrics Serial No.: 23-2322 Manufacturer: _N_/_A __________ _

Model: 38 DL Plus Serial No.: 703091 Type: Step Wedge Serial No.:..;;..N""/"-'A'-------------

Serial No.: 161384110 Size:

o.s*

Freq:

5MHz Couplant*

• . 61 dB Mod 1.

0798 Ref./S1m. Block Temp.:

N/A 0 f Gam.

n

e. --------------Material/Comp. Temp.:

N/A oF Couplant:

..._Uc:.ltra=g.._e;;;;lc..:ll=--------

Range: 1.00

1. of Elements:

2 Batch No.: 21K029

-=~~-----------

Comments UT exam on underwater suppression pool wall plates; 1-FP-06D, 1-FP-08A, 1*WP-02A, 1-WP-088, 1-FP-03C per direction of engineering. See supplemental pages for grid layout and readings.

Results:

NRI Percent Of Coverage Obtained > 90%:

RI 1000/o Examiner Level Ill <

Signature MatthewsL Shane M.

~ c=>-

Examiner N/A Other I

IN/A Level Signature Level Signature IO ~..;;..N::,.:.:Ac__ ___________________________ ________ _

Exam Date 04/18/2024 Exam Date Date Reviewed Previous Data:

N/A 1/-eJ-z Date

EC 0000641238 Attachment 2 Page 2 of 3 Supplemental Report Constellat1or\

Summary No.: --=B....;;O~P_-..;;..09;;;;..3=-------------

Examiner Matthews, Shane M. ~Level: _I_n __ _

Reviewer Examiner N/ A Level:

Site Review Other N/A Level:

ANII Review Comments:

None Sketch or Photo:

O:\Outage Data\Limerick\1R20\BOP\Data\10-S199 SUP. POOL (UT-035).jpg QUAD-3 FLOOR PANEL 1-FP-03C

• BULGE INDICATION DETAILS 0

' P11n&t 110'

~ -

100 This record provides suppremental loc.ation a11d dimensional data fof the bulge a<ea ;dent1fled on Panel l *FP-03C as wen as locations when~ UT th1cknes~ reac:hogs were taken The VT readioas/rcsulls included he1e1n

<ho~ld be con,odered INFORMATION ONLY; Rele, to the fornial UT Report from the lIcc-ri~cc provided UT ll'lspector for the record UT reading,esulU UAl(CHA.St, Al 8.Asl A

B C

0 or OU 11:'.R WALL

' 03\!

O.lOI Q_)28 O.ll8

\

0.320,

0.32i 0.314 O.Bl 0.1'1'.l v

0 0 30') I o 323 OJU 0_311 I 0 3l'>

~

, s "

z 4

0.32:9 I

. O.Hl 0 324 0 339

• 0 ]IS 5

0_32S I O JIB 0 328 0 147 I O l 29 ti 0.11!

Q_H!

0 317 ons 0 31S 7

0.31~

0 ID9 0 299 o lll I 0.331 LfA~ CHAI!

ADJOININGFP*03C 6UI.G£ AR[A Indication ID J-fP-OJC-3-2 (2024~

0.3 ll -1* 0,302

-Dvtg-e rndic ahon; 6 s**-. 14 o** a,ea w11 h 2

0.320 0.323 long axis. perpendicuhH to lhc cuter w.jjill, 3

0 309, 0.323 0.322 0.317 l -FP-03C

• Approx J/4"'to 1/2 ' upwa rd detle,tmn; f*-

Annl1lvs

• loco1ted at Z6S' N:lm"lh in the annul Ui 4

O 329 0.331 0.324 0_339 Are3 c1reil aisdacl':!nl to fP-03( ;

• Reference Constelldtl0" AA No s

I Q_32S 0 303 0.328 0.347 04766BS

-*+ -

i

-Jdentified*o,ve No 133 6

I 0.312 i 0 332 0.317 0_315

• UI Ril!ad1ngs Dive No 276 i*-

7

O 326 0.309 0.299

0_323 0.299 0-335 0.315 0.329 0.315 0.332 Report No.

LGS-1-24-UT-035 Page:..;;c2'---__

10" x 14" grid,et-up with 2" sp~cing.

flea di ngs ta ken, n e3ch 2" grid,qu3re.

of 3 -----

EC 0000641238 Attachment 2 Page 3 of 3 Supplemental Report

.:=- Constellation Report No.: LGS-1-24-UT-035 Page: _;;;;_3 __ of _3 __

Summary No.: _BO_P-_09~3 _____

Examiner Matthews, Shane M~evel: Ill z:.--

Examiner N/ A Level:

Other N/A Level:

. *~ewer :1':!~ ~~~

Date: q -u-25/-

soe Re'Aew t¥,-J tJ/111:1 fllt2_ Date: I'- lD-Z'I ANH Review

/) /;J Date:

I Comments:

None Sketch or Photo:

O:\Outage Data\Limerick\1R20\BOP\Data\10-S199 SUP. POOL (UT-035) (2).jpg Floor Panel UT Readings - Information Only No.

Panel ID UT Measurements (inches)

Gen. Corr.

Sound Area Steel Area 1

1-WP-088 0.320 0.280 2

1-WP-02A 0.283 0.243 3

1FP-08A 0.296 0.280 4

1-FP-060 0.290 0.251