ML21201A311

Replacement Steam Dryer Visual Inspection Results

ML21201A311
Person / Time
Site:	Browns Ferry
Issue date:	07/20/2021
From:	Rasmussen M Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML21201A311 (9)

Text

Post Office Box 2000, Decatur, Alabama 35609-2000 July 20, 2021 10 CFR 50.4 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Unit 2 Renewed Facility Operating License No. DPR-52 NRC Docket No. 50-260

Subject:

Unit 2 Replacement Steam Dryer Visual Inspection Results (U2R21)

Enclosed is a summary of the results of the visual inspections of the Unit 2 Replacement Steam Dryer that were performed during the recent refueling outage (U2R21). The inspections are required to be performed in accordance with Operating License Condition 2.C(18)(g) during the first two scheduled refueling outages after reaching full Extended Power Uprate conditions. This first report for Unit 2 is being submitted pursuant to Operating License Condition 2.C(18)(h) which requires that the results of the inspection be submitted in a report within 90 days following startup.

There are no new regulatory commitments in this letter. Should you have any questions concerning this submittal, please contact J. L. Paul, Site Licensing Manager, at (256) 729-2636.

Respectfully, Matthew Rasmussen Site Vice President

U.S. Nuclear Regulatory Commission Page 2 July 20, 2021

Enclosure:

Browns Ferry Unit 2 Replacement Steam Dryer (RSD) Inspection Results from the First Refueling Outage (U2R21) Following Installation of RSD and Implementation of Extended Power Uprate cc (w/ Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant

ENCLOSURE BROWNS FERRY NUCLEAR PLANT UNIT 2 Browns Ferry Unit 2 Replacement Steam Dryer (RSD) Inspection Results from the First Refueling Outage (U2R21) Following Installation of RSD and Implementation of Extended Power Uprate See attached

Browns Ferry Unit 2 Replacement Steam Dryer (RSD) Inspection Results from the First Refueling Outage (U2R21) Following Installation of RSD and Implementation of Extended Power Uprate 1

Purpose This report provides the results of visual inspections of the Replacement Steam Dryer (RSD) as required by the Browns Ferry Unit 2 Renewed Facility Operating License No. DPR-52, License Condition 2.C.(18).(h). This license condition requires that the results of the visual inspections of the RSD be submitted to the NRC within 90 days following startup from each of the first two respective refueling outages.

Summary The Unit 2 RSD was inspected from March 1 through 14, 2021, during the Spring 2021 refueling outage (Unit 2 Refueling Outage 21: U2R21). This was the first refueling outage following installation of the RSD in March 2019 during Unit 2 Refueling Outage 20 (U2R20) and operation at Extended Power Uprate (EPU) conditions since June 2019. The inspections were performed in accordance with GE Hitachi Nuclear Energy Report No. 003N5663, Revision 2 (Tennessee Valley Authority (TVA) Browns Ferry Nuclear Station (BFNS): Recommendations for Future Inspections - Replacement Steam Dryer). The RSD design and the materials and fabrication processes utilized are expected to result in significantly improved resistance to stress corrosion cracking. Therefore, the inspection recommendations in the GEH report focus primarily on the locations that may be susceptible to fatigue from flow-induced vibration. The locations identified are those indicated to have relatively significant cyclic loading during the dryers operation, as determined by detailed stress analyses.

Tables 1 (Frequency of Recommended Locations Based on Analysis and 2 (Description of Recommended Inspections Locations) of the GEH Report list locations that are considered the most susceptible for fatigue cracking based on BWR dryer experience and stress analysis. All accessible weld and weld heat-affected zone (HAZ) base metal surfaces of the RSD were visually inspected during U2R21, with a total scope of 646 points. The summary results of the inspections can be found in the table starting on the next page.

The following explanations apply to the table:

NRI:

No Relevant Indication RI:

Relevant Indication The parentheses after each Inspection Location refer to the number of points inspected for each.

Browns Ferry Unit 2 Replacement Steam Dryer (RSD) Inspection Results from the First Refueling Outage (U2R21) Following Installation of RSD and Implementation of Extended Power Uprate 2

Inspection Location Method Inspection Result Condition Report (if RI)

Disposition STEAM DRYER ID Divider Plate Welds & HAZs (32)

VT-1-89 NRI Trough Side Plate to Base Plate Weld &

HAZs (6)

VT-1-89 NRI Hood Vertical / Horizontal Welds &

HAZs (12)

VT-1-89 NRI Perforated Plate to Trough Side Plate Weld & HAZs (22)

VT-1-89 NRI Trough Spacer Pin Weld & HAZs (6)

VT-1-89 NRI Skirt to Support Beam Weld & HAZs (8)

VT-1-89 NRI Guide Channel to Tee Weld & HAZs (4)

VT-1-89 NRI Skirt to Tee Weld & HAZs (12)

VT-1-89 NRI Drain Pipe to Trough Base Plate Weld &

HAZs (12)

VT-1-89 NRI Drain Pipe to Elbow Weld & HAZs (21)

VT-1-89 NRI Drain Elbow to Pipe Weld & HAZs (11)

VT-1-89 NRI Drain Elbow to Skirt Weld & HAZs (12)

VT-1-89 NRI Collar to Skirt Weld & HAZs (12)

VT-1-89 NRI Cover Plate to Hood Weld & HAZs (2)

VT-1-89 NRI Trough Base Plate to Hood Weld &

HAZs (4)

VT-1-89 NRI Hood Support Stiffener Assembly, Stiffener to Hood Support Tee Weld &

HAZs, 360 degree weld (16)

VT-1-89 NRI Hood Support Stiffener Assembly, Stiffener to Trough Weld & HAZs, 360 degree weld (16)

VT-1-89 NRI Skirt to Lower Support Ring Weld plus 2 Splice Bars & HAZs (2)

VT-1-89 NRI Skirt to Lower Support Ring Weld &

HAZs (6)

VT-1-89 NRI Splice Bar Attachment Weld and HAZs (4)

VT-1-89 NRI Trans Brace to Upper Support Ring Weld & HAZs (2)

VT-1-89 NRI Trans Brace Coupler Weld & HAZs (1)

VT-1-89 NRI Trans Brace Plate Welds & HAZs (8)

VT-1-89 NRI Trans Brace Support Welds & HAZs (12)

VT-1-89 NRI Base Plate to Upper Support Ring Weld

& HAZs (4)

VT-1-89 NRI Base Plate to Upper Support Ring/Latch Assembly Welds & HAZs (2)

VT-1-89 NRI Base Plate to Upper Support Ring/Lifting Assembly Welds & HAZs (2)

VT-1-89 NRI Cover Plate to Upper Support Ring Weld

& HAZs (2)

VT-1-89 NRI Splice Bar to Upper Support Ring and Trough Welds & HAZs (2)

VT-1-89 NRI USR Segment Weld & HAZs (4)

VT-1-89 NRI

Browns Ferry Unit 2 Replacement Steam Dryer (RSD) Inspection Results from the First Refueling Outage (U2R21) Following Installation of RSD and Implementation of Extended Power Uprate 3

Inspection Location Method Inspection Result Condition Report (if RI)

Disposition Skirt to Upper Support Ring Weld &

HAZs (6)

VT-1-89 NRI STEAM DRYER OD 000 Degree Pad Welds & HAZs (1)

VT-1-89 NRI Steam Dryer Outer Banks Access Panel Welds & HAZs 000 Side (6)

VT-1-89 NRI Steam Dryer Outer Banks Access Panel Welds & HAZs 180 Side (6)

VT-1-89 NRI Both Sides of the Bank to Divider Plate Weld & HAZs (16)

VT-1-89 NRI Both Sides of the Bank to Exhaust Plenum Plate Vertical Weld & HAZs (20)

VT-1-89 NRI Hood to Cover Plate Horizontal Weld &

HAZs (2)

VT-1-89 NRI Hood to Top Cap Horizontal Weld &

HAZs (6)

VT-1-89 NRI Perforated Plate to Bank Top Cap Weld

& HAZs (6)

VT-1-89 NRI Perforated Plate to Trough Side Plate Weld & HAZs (6)

VT-1-89 NRI Trough Side Plate to Base Plate Weld

& HAZs (6)

VT-1-89 NRI Both Sides of the Hood Support to Trough Weld & HAZs (16)

VT-1-89 NRI Perforated Plate to End Plate Weld &

HAZs (4)

VT-1-89 NRI Perforated Plate to Perforated Plate Weld & HAZs (16)

VT-1-89 NRI Perforated Plate to End Plate Weld &

HAZs from Trough Base Plate to Hood Cap (8)

VT-1-89 NRI Trough Spacer Pin Weld & HAZs (6)

VT-1-89 NRI Bank Tie Rod Bolting Welds & HAZs for all 6 locations on the 000 Deg Side (6)

VT-1-89 NRI Bank Tie Rod Bolting Welds & HAZs for all 6 locations on the 180 Deg Side (6)

VT-1-89 NRI Hood to Trough Base Plate Horizontal Weld & HAZs (4)

VT-1-89 NRI Both Sides of the Divider Plate to Inner Plate Welds & HAZs (6)

VT-1-89 NRI Drain Channel to Upper Support Ring Horizontal Weld & HAZs (4)

VT-1-89 NRI Drain Channel to Support Beam Weld &

HAZs (8)

VT-1-89 NRI Drain Channel to Support Ring Tab Welds & HAZs (20)

VT-1-89 NRI Guide Channel to Drain Channel Tee Vertical Weld & HAZs (4)

VT-1-89 NRI

Browns Ferry Unit 2 Replacement Steam Dryer (RSD) Inspection Results from the First Refueling Outage (U2R21) Following Installation of RSD and Implementation of Extended Power Uprate 4

Inspection Location Method Inspection Result Condition Report (if RI)

Disposition Drain Channel to Drain Channel Tee Vertical Weld & HAZs (8)

VT-1-89 NRI Skirt to Drain Channel Tee Vertical Weld

& HAZs (4)

VT-1-89 NRI Doubler Plate to Upper Support Ring &

HAZs (8)

VT-1-89 NRI General Overview of the Side Surfaces (4)

VT-1-89 NRI General Overview of the Top Surfaces (1)

VT-1-89 NRI Hood to Inlet End Plate Vertical Weld &

HAZs (18)

VT-1-89 NRI Both Hood to Hood Tee Vertical Welds

& HAZs (4)

VT-1-89 NRI Hood to Hood Tee Vertical Weld &

HAZs (18)

VT-1-89 NRI Both Sides of the Hold Down Assembly to Exhaust Plenum Plate Vertical Weld

& HAZs (4)

VT-1-89 NRI Hold Down Assembly to Trough Base Plate Horizontal Weld & HAZs (2)

VT-1-89 NRI Lifting Assembly - Support Ring Anchor Weld & HAZs (4)

VT-1-89 NRI Lifting Assembly - Bolting (4)

VT-1-89 RI 1676166 Repaired Lifting Assembly - Lower Bracket and Welds Plus HAZs (4)

VT-1-89 NRI Lifting Assembly - Middle Bracket and Welds Plus HAZs (4)

VT-1-89 NRI Lifting Assembly - Rod to Anchor Weld

& HAZs (4)

VT-1-89 NRI Lifting Assembly - Upper Bracket and Welds Plus HAZs (4)

VT-1-89 NRI Latch Box General Condition for Evidence of Handling Damage (2)

VT-1-89 NRI Lower Guide Channel General Condition for Evidence of Handling Damage (2)

VT-1-89 NRI Lower Support Ring to Guide Channel Horizontal Weld & HAZs (2)

VT-1-89 NRI Lower Support Ring to Skirt Horizontal Weld & HAZs (6)

VT-1-89 NRI Lower Support Ring Splice Bar General Condition for Evidence of Handling Damage (2)

VT-1-89 NRI Splice Bar Attachment Weld & HAZs (8)

VT-1-89 NRI Seismic Lug General Condition for Evidence of Handling Damage, also Associated Bolting, Welds & HAZs (2)

VT-1-89 NRI Bank Tie Bar Welds & HAZs (34)

VT-1-89 NRI Trough Base Plate Center Horizontal Weld & HAZs (1)

VT-1-89 NRI

Browns Ferry Unit 2 Replacement Steam Dryer (RSD) Inspection Results from the First Refueling Outage (U2R21) Following Installation of RSD and Implementation of Extended Power Uprate 5

Inspection Location Method Inspection Result Condition Report (if RI)

Disposition Top Flange to C-Channel to Hood Cover Weld & HAZs (2)

VT-1-89 NRI Upper Support Ring Horizontal Weld &

HAZs (26)

VT-1-89 NRI Upper Support Ring Tapered Pin Seal Weld & HAZs (8)

VT-1-89 NRI Upper Support Ring to Splice Bar Vertical Weld & HAZs (4)

VT-1-89 NRI Upper Support Ring to Guide Channel Horizontal Weld & HAZs (2)

VT-1-89 NRI Upper Support Ring to Skirt Horizontal Weld & HAZs (2)

VT-1-89 NRI Inspection Results Relevant indications were noted at only one inspection location during inspections performed during U2R21. They are described as follows:

(1) BFN2-SD OD LA 220 Eye - Bolting and BFN2-SD OD LA 320 Eye - Bolting: The Steam Dryer Lifting Assembly Bolts at 220° and 320° were observed to have sheared at the shaft and the nut was no longer present. Both bolts were retrieved and a failure analysis was performed.

The analysis concluded that it appeared that the presence of small cyclic loads on the bolts combined with a mildly aggressive local environment containing chlorides let to the corrosion-assisted fatigue failure of the bolts (a possible source of the cyclic load is a vibration of the dryer unit locking pin assembly).

Disposition of Indications Condition Report (CR) 1676166 was initiated to disposition both relevant indications. The disposition is as follows:

(1) BFN2-SD OD LA 220 Eye - Bolting and BFN2-SD OD LA 320 Eye - Bolting: The sole function of the Steam Dryer Lifting Assembly Bolts at 220° and 320° is to prevent rotation of the lifting lug. Therefore, a repair was decided upon to tack weld the remaining bolt assembly as this would prevent rotation of the lifting lug and restore functionality. (NOTE: Per the recommendation of the inspection vendor, the repair was performed not only for the bolts that were sheared but also was performed preemptively for the intact bolts at 40° and 140° to eliminate any future concerns about loose parts in the reactor vessel.)

Browns Ferry Unit 2 Replacement Steam Dryer (RSD) Inspection Results from the First Refueling Outage (U2R21) Following Installation of RSD and Implementation of Extended Power Uprate 6

Conclusion A completed baseline inspection of the Browns Ferry Unit 2 Replacement Steam Dryer (RSD) was performed during the Spring 2021 Refueling Outage 21. This baseline inspection included successful visual inspection of all inspection locations required by the Facility Operating License Condition 2.C.(18).(h) for inspection of the RSD. All observations were acceptable for the locations inspected. There were two relevant indications that were adequately dispositioned.

The subsequent inspection scope of the RSD will be performed during Unit 2 Refueling Outage 22 (U2R22) in Spring 2023, and the results will be provided at that time consistent with the Browns Ferry Operating License.