ML20031C928

Results of Visual Inspections of Unit 3 Replacement Steam Dryer

ML20031C928
Person / Time
Site:	Peach Bottom
Issue date:	01/31/2020
From:	Pat Navin Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CCN 20-13
Download: ML20031C928 (6)

Text

Exelon Generation.

DPR-56 Operating License 2.C(15)(g)

CCN 20-13 January 31, 2020 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington DC 20555-0001 Peach Bottom Atomic Power Station, Unit 3 Renewed Facility Operating License No. DPR-56 NRC Docket No. 50-278

Subject:

Results of Visual Inspections of Unit 3 Replacement Steam Dryer

References:

1. WCAP-17635-P, Rev. 3, Peach Bottom Atomic Power Station Units 2 and 3 Replacement Steam Dryer Comprehensive Vibration Assessment Program (CVAP), April 2014.

2. PBAPS Extended Power Uprate License Amendment Request - Supplement 24 - Response to Request for Additional Information, dated April 11, 2014.

3. NRC - Issuance of Amendments - PBAPS Units 2 and 3 Extended Power Uprate, License Amendments 293/296 (including NRC Safety Evaluation Report), dated August 25, 2014.

4. Peach Bottom Atomic Power Station, Unit 3 - Results of Visual Inspections of Replacement Steam Dryer, Letter from Exelon to NRC dated January 30, 2018, ML18030A190.

Enclosed is a summary of the results of the visual inspections of the Unit 3 Replacement Steam Dryer that were performed during the second refueling outage after reaching EPU conditions (P3R22). The inspections are required to be performed following the guidelines of WCAP-17635-P in accordance with Operating License Section 2.C(15)(f). This second report is being submitted pursuant to Operating License Condition 2.C(15)(g) which requires that the results of the inspection be submitted in a report within 90 days following startup from each of the first two respective refueling outages.

The inspection was performed in accordance with WCAP-17635, Rev. 3 (Reference 1) which was submitted to the NRC in the Reference 2 letter and referenced by the NRC in the NRC Safety Evaluation Report for Extended Power Uprate (Reference 3) .

If you have any questions con7 erni this letter, please contact Randal Schmidt at (610) 765-5236. 2 ~

Patrick D. Navin Site Vice President Peach Bottom Atomic Power Station

U.S. Nuclear Regulatory Commission Results of Visual Inspections of Unit 2 Replacement Steam Dryer in the Second Refueling Outage After Reaching EPU Conditions Docket No. 50-277 Page 2 CCN: 20-13 Attachment - Peach Bottom Unit 3 Steam Dryer Inspection Results from the Second Refueling Outage Following Installation of Steam Dryer and Implementation of Extended Power Uprate cc: Regional Administrator, Region I USNRC USNRC Senior Resident Inspector, PBAPS D. J., Allard, Pennsylvania Bureau of Radiation Protection D. Tancabel, State of Maryland

ATTACHMENT Peach Bottom Unit 3 Steam Dryer Inspection Results from the Second Refueling Outage Following Installation of Steam Dryer and Implementation of Extended Power Uprate

Attachment Peach Bottom Unit 3 Steam Dryer Inspection Results from the Second Refueling Outage Following Installation of Steam Dryer and Implementation of Extended Power Uprate Page 1of3

Purpose:

This report provides the results of the visual inspections of the Replacement Steam Dryer (RSD) as required by the Peach Bottom Unit 3 Renewed Facility Operating License No DPR-56, License Condition 2.C(15)(g). This license condition requires that the results of the inspection be submitted in a report within 90 days following startup from each of the first two respective refueling outages. This report covers the second refueling outage inspection.

Summary:

The Unit 3 Replacement Steam Dryer was inspected during the fall 2019 refueling outage, P3R22, in October 2019. This was the second refueling outage following installation of the RSD in November 2015, P3R20, and operation at Extended Power Uprate (EPU) conditions which started in December 2015. The inspections were performed in accordance with the requirements of WCAP-17635-P and recommendations from the manufacturer, Westinghouse.

The inspection scope was defined based upon Operating Experience (OE) for the Westinghouse steam dryer design from previous installations, high cyclical stress locations determined from the dryer acoustic analysis, similarities to BWRVI P-139-A inspection locations and finally, by higher stress locations where solution annealing or polishing of structural welds had not been performed during fabrication. A total of 68 inspections were performed.

All observations were acceptable for the structural components and welds inspected. In total, five non-structural indications were identified. Three indications were initially found in P3R21 and two additional indications were newly identified in P3R22. All indications have no impact on the structural qualification of the steam dryer. These will be discussed further in the next section of this report.

Inspection Results:

Five indications were found at three general locations: two were associated with AA 365270 W7 fillet weld for the lifting rod interface to the support ring, two were associated with the AA 365270 W9 tack weld for the lifting lug to lifting rod interface, and one was associated with the steam dryer seismic block shim. All are in non-structural locations.

In the previous outage, two indications were associated with AA 365270 W7 fillet weld for the lifting rod interface to the support ring were identified. Re-inspections from this outage found no change in the indications. These indications were confirmed not to extend into the rods.

In the previous outage one indication was identified with the AA 365270 W9 tack weld for the lifting lug to lifting rod interface. Re-inspection from this outage found a slight separation of the tack weld to the lifting rod. A new indication was found at a different tack weld for lifting lug to lifting rod interface.

Last outage gouge marks were observed on one of the steam dryer seismic block shims. This outage's re-inspection found no change to the gouge marks.

No other recordable indications were identified during the P3R22 RSD inspections.

Attachment Peach Bottom Unit 3 Steam Dryer Inspection Results from the Second Refueling Outage Following Installation of Steam Dryer and Implementation of Extended Power Uprate Page 2 of 3 Disposition of Indications:

The lifting rod assembly has two basic components, a rod that is threaded into the support ring and a lug that is threaded into the rod. The lifting rod assembly's function is for dryer handling and a hold-down function which limits the possible lift of the dryer during faulted condition load.

The AA 365270 W7 fillet welds for the lifting rod interface to the support ring are non-structural welds and were used for positioning and rod anti-rotation during construction. In that function, as construction welds, they do not carry any primary load. The lifting rod functions do not depend on the non-structural AA 365270 W7 fillet welds. During plant operation, the positioning at the top and bottom of these rods is guaranteed by the threaded portions of the rod; and the anti-rotation is maintained by a bracket welded to the rod. The design stress margins for the bracket remain unchanged by the cracking of the construction fillet welds at the bottom support ring location. These indications do not impact the functions of the lifting rod assembly.

The AA 365270 W9 tack welds for the lifting lug to lifting rod interface are also non-structural welds and are used for anti-rotation of the lifting rod lugs. Anti-rotation ensures alignment with the lifting strongback using to handle the dryer and to maintain a maximum gap with the hold-down brackets located in the RPV head. While the tack welds are cracked, the weld is still physically present. This serves as a physical interference and prevents the lug from rotating down, which would cause an alignment issue during handling operations. The cracked tack welds (and their jagged edges) also make it highly unlikely that the lug could unthread from the rod. In the case that this did occur during operation, the lifting lug cannot become disengaged from the rod due to the hold-down brackets located in the RPV head. If significant rotation did occur during operation, then this would be found during steam dryer handling activities at the next refueling outage due to misalignment with the lifting strongback. This is not the current status as there is only a slight gap in the cracked tack welds.

The AA 365270 W7 and W9 non-structural welds are not credited to show ASME Ill Code compliance for the lifting or hold-down function. The purpose for including these welds in the inspection plan was primarily due to their inclusion in BWRVIP-139-A, which requires inspection of similar locations on GE steam dryer based on previous operating experience. Based on review of the purpose of the fillet welds, the critical aspect of the inspection for the rod attachment to the ring is the integrity of the threaded connection at the support ring location.

The inspection has confirmed no crack extension into the rod or threads has occurred, and none are anticipated.

At this time, no repair is required to the non-structural welds. The AA 335740 W7 fillet and W9 tack weld indications will be re-inspected in future outages to confirm no crack extension into the rod occurs at either location.

The shim found with gouge marks is located on the vertical side of the 90-degree steam dryer seismic block. The function of the seismic block is to transfer lateral and radial loads from dryer to RPV steam dryer support brackets during normal operations and transient events. The gouges were most likely caused by damage on the RPV steam dryer support brackets from a past event prior to installation of the RSD. The gouges do not impact the function to transfer loads to the support brackets during normal operation or transient events. This area will be periodically inspected. No repair is required.

Attachment Peach Bottom Unit 3 Steam Dryer Inspection Results from the Second Refueling Outage Following Installation of Steam Dryer and Implementation of Extended Power Uprate Page 3 of 3

==

Conclusion:==

An inspection of the Peach Bottom Unit 3 Replacement Steam Dryer was performed during the fall 2019 refueling outage P3R22. This was the second refueling outage inspection following implementation of EPU. The inspection included visual examination of all locations required by the Facility Operating License Condition 2.C(15)(f) for the Replacement Steam Dryer. Additional locations were also inspected. All observations were acceptable for the structural components and welds inspected. There were four non-structural welds found with indications and were determined to be acceptable with future inspections required. Also, gouges were found on one seismic block shim. This was also determined to be acceptable with future monitoring.