ML20240A142

Day Inservice Inspection Report for Interval 4, Period 2, (B1R23)

ML20240A142
Person / Time
Site:	Byron
Issue date:	09/17/2020
From:	Kanavos M Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
2020-0056
Download: ML20240A142 (5)

Text

Byron Generating Station 4450 North German Church Rd Exelon Generation Byron. IL 61010-9794 www.exeloncorp.com September 17, 2020 LTR: BYRON 2020-0056 FILE: 1.10.0101 (1D.101)

United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 1 Facility Operating License No. NPF-37 NRC Docket No. STN50-454

SUBJECT:

Byron Station Unit 1 90-Day lnservice Inspection Report for Interval 4, Period 2, (B1 R23)

The subject 90-Day lnservice Inspection Report for the Byron Station Unit 1, Refueling Outage Twenty-Three (B 1R23) is being submitted pursuant to the requirements of Article IWA-6000, "Records and Reports" of Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code 2007 Edition I 2008 Addenda.

This letter provides a copy of Form OAR-1 Owner's Activity Report for inservice inspection activities performed during the previous fuel cycle. This report meets the requirements of the ASME Code Case N-532-5, "Repair/Replacement Activity Documentation Requirements and lnservice Summary Report Preparation and Submission." The report covers the inservice inspections conducted prior to and during the Unit 1 Spring 2020 refueling outage.

If there are any questions regarding this matter, please contact Ms. Zoe Cox, Regulatory Assurance Manager, at (815) 406-2800.

P----

Mark E. Kanavos Site Vice President Byron Generating Station MEK/DA/ZC/rm Attachment

FORM OAR-1 OWNER'S ACTIVITY REPORT Report Number B1 R23

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~--~

Plant Byron Generating Station, 4450 N German Church Road, Byron Illinois 61010 Unit No. Commercial Service Date September 16, 1985 Refueling Outage Number B1R23 (if applicable)

Current Inspection Interval Fourth Inspection Interval (ISi), Third Inspection Interval (CISI),

(1 ", 2°*, 3**, 4 1h, other)

Current Inspection Period Second Inspection period (ISi and CISI)

(1", 2°*. 3)

Edition and Addenda of Section XI applicable to the inspection plans ASME Section XI 2007 Edition through 2008 Addenda Date and Revision of inspection plans January 4th, 2017Rev1, August 18th, 2018 Rev 2 Edition and Addenda of Section XI applicable to repair/replacement activities, if different than the inspection plans Same as above Code Cases used for inspection and evaluation: N-508, N-513-4, N-532-5, N-639, N-706, N-722-1, N-729-4, N-731, N-770-2, N-798, N-800 (if applicable, including cases modified by Case N-532 and later revisions)

CERTIFICATE OF CONFORMANCE I certify that (a) the statements made in this report are correct; (b) the examinations and tests meet the Inspection Plan as required by the ASME Code,Section XI; and (c) the repair/replacement activities and evaluations supporting the completion of B 1R23 conform to the requir~ Section XI. / . *..__ _ (refueling outage number)

Sigood ~~*~ (Owner :OW:::::::: Date 8/10/2020 CERTIFICATE OF INSERVICE INSPECTION I, the undersigned, holding a valid commission issued by the National Board of Boiler and Pressure Vessel Inspectors and employed by The Hartford Steam Boiler Inspection and Insurance Company of Hartford, Connecticut have inspected the items described in this Owner's Activity Report, and state that, to the best of my knowledge and belief, the Owner has performed all activities represented by this report in accordance with the requirements of Section XI.

By signing this certificate neither the Inspector nor his employer makes any warranty, expressed or implied, concerning the repair/replacement activities and evaluation described in this report. Furthermore, neither the Inspector nor his employer shall be liable in any manner for any personal injury or property damage or a loss of any kind arising from or connected with this inspection.

Commissions (I nspector';s]Qnai (National Board Number and Endorsement)

Date Page 1 of 3

TABLE 1 ITEMS WITH FLAWS OR RELEVANT CONDITIONS THAT REQUIRED EVALUATION FOR CONTINUED SERVICE Examination Examination Item Item Description Evaluation Description CateQorv Number Leak in Pipe to nozzle weld IR 04228044 upstream of OSX007 (U-0 CC HX D-8 02.10 N-513-4 evaluation performed under OCC01A SX OUTLET ISOL VLV)

EC 627561 TABLE 2 ABSTRACT OF REPAIR/REPLACEMENT ACTIVITIES REQUIRED FOR CONTINUED SERVICE Code Item Description Date Repair/Replacement Class Description Of Work Completed Plan Number 3 OSX007 Weld Repair on SX through wall leak 05/29/2020 WO 04896208-01 Repairs and machining of OW001 CB 3 OW001CB 1/15/2019 WO 01819747-01 Condenser Chiller SX inlet and outlet pipe flange(s) 3 OSX33A 11/19/2018 WO 04750965-01 face repair/replace 3 OW001CA Perform OW001 CA Condenser Repairs 11/19/2018 WO 04691470-01 Page 2 of 3

ATTACHMENT 2 81 R23 CONTAINMENT ISi (IWE/IWL) RESULTS 81 R23 CONTAINMENT ISi (IWE/IWL) ACTIVITIES During the B1 R23 outage, examinations were completed of the Unit 1 containment liner for the IWE requirements. In addition, during the 23rd fuel cycle, the 35th-year tendon surveillance for Unit 1 and Unit 2 was completed .

ASME IWE/IWL REPORT OF CONTAINMENT DEGRADATION During the B1 R23 outage, examinations were completed of the Unit 1 containment liner to comply with the requirements of IWE-2500.

The following provisions of 10CFR50.55a were reviewed for conditions that require reporting in the B1 R23 ISi Summary Report.

Section XI Concrete containment examinations:

No conditions were found that warranted inclusion in this report as specified by (b)(2)(viii)(E).

Section XI Metal containment examinations:

Conditions were found that warranted inclusion in this report as specified by (b)(2)(ix)(A)(2).

==

Description:==

General Visual examinations of Accessible Surface Areas (Category E-A, Item 1.11) and Moisture Barriers (Category E-A, Item 1.30) of Containment Vessel Pressure Retaining Boundary were performed to meet the periodic inspection requirements of ASME Section XI, Table IWE-2500-1 .

Augmented examinations (Category E-C, Item 4.11 and 4.12) of containment liner were performed at 37 locations below the moisture barrier in accordance with the requirements of ASME Section XI , Table IWE-2500-1, "Category E-C, Containment Surfaces Requiring Augmented Examination". The scope of the examinations included locations that exhibited metal thickness losses greater than 1 /64" in B1 R21.

Inaccessible areas of the liner plate were made accessible by removing approximately 41' of the moisture barrier in B1 R23 under WO #04854505 . The as found condition of the degraded areas behind the moisture barrier is surface corrosion of the carbon steel containment liner. The observed environment is dry with inconsistently scattered areas of small pitting.

Recordable indications were found and documented in IR 04328319 on the following areas:

Area C1 Location 7: Surface rust and pitting 1/16 inches deep.

Area C3 Location 2: Surface rust and pitting 3/64 inches deep.

Area C11 Location 6: Surface rust and pitting 3/64 inches deep.

Evaluation and results:

The containment liner plate material loss due to inactive corrosion exceeded the allowable limit of 10% nominal liner thickness per the ASME code Section XI, Paragraph IWE-3521 (a) at Area C1 Location 7, Area C3 Location 2 and Area C11 Location 6. ASME code Section XI, Subsection IWE states when liner plate metal loss of more than 10% is identified then the condition shall be evaluated for acceptability or repair/replacement. As a supplemental examination, ultrasonic examinations were performed at the three locations exceeding 10%

metal loss. The results are as follows:

Minimum UT reading at Area C1 Location 7: 0.269 inches (UT Report #81R23-UT-030)

Minimum UT reading at Area C3 Location 2: 0.234 inches (UT Report #81 R23-UT-031)

Minimum UT reading at Area C11 Location 6: 0.252 inches (UT Report #81 R23-UT-032)

From the UT reports, it can be seen that Area C1 Location 7 and AREA C11 Location 6 still remain above the nominal thickness of the containment liner plate, which is 0.250". The UT results at AREA C3 Location 2 is acceptable per NDIT No. 8YR-99-226 which provides minimum allowable thickness for the containment liner plate to be 0.125 inches. The three locations exceeding 10% metal loss were previously examined in 81 R21, accepted per EC 618724 and remained essentially unchanged in 81 R23, therefore no longer require successive examination under Table IWE-2500-1, Examination Category E-C. Metal loss at Areas A 1 through A7 did not exceed the 10% nominal liner thickness and met the acceptance standards of IWE-3521 (a), therefore do not require augmented examination in accordance with Table IWE-2500-1, Examination Category E-C.

Corrective Actions:

All excavated areas have been properly cleaned and coated with Level 1 coating and new moisture barrier has been installed. These are corrective measures to further protect the containment liner plate from any future corrosion. The minimum wall thickness for each area has met the owner established acceptance criteria per NDIT No. 8YR-99-226.