ML18030A190
| ML18030A190 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 01/30/2018 |
| From: | Pat Navin Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML18030A190 (9) | |
Text
Exelon Generat ion DPR-56 Operating License 2.C(15)(g)
January 30, 2018 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 NRG 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. NRG- Issuance of Amendments - PBAPS Units 2 and 3 Extended Power Uprate, License Amendments 293/296 (including NRC Safety Evaluation Report), dated August 25, 2014.
Enclosed is a summary of the results of the visual inspections of the Unit 3 Replacement Steam Dryer that were performed during the recent refueling outage (P3R21 ). 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 first 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 NRG in the Reference 2 letter and referenced by the NRG in the NRG Safety Evaluation Report for Extended Power Uprate (Reference 3).
U.S. Nuclear Regulatory Commission Unit 3 Replacement Steam Dryer Visual Inspection Docket No. 50-278 Page 2 Wyou have any questions concerning this letter, please contact Bryce Sessions at (717) 456-386/M1 Patrick D. Navin Site Vice President Peach Bottom Atomic Power Station CCN: 17-95 Attachment - Unit 3 License Condition 2.C{15)(g) Replacement Steam Dryer Inspection Results cc: Regional Administrator, Region I USN RC USN RC Senior Resident Inspector, PBAPS D. J., Allard, Pennsylvania Bureau of Radiation Protection S. T. Gray, State of Maryland
Attachment - Results of Visual Inspection for PBAPS Unit 3 Replacement Steam Dryer Page 1 of 7 ATTACHMENT Unit 3 License Condition 2.C(15){g) Replacement Steam Dryer Inspection Results
Attachment - Results of Visual Inspection for PBAPS Unit 3 Replacement Steam Dryer Page 2of 7 Peach Bottom Unit 3 Steam Dryer Inspection Results from the First Refueling Outage Following Installation of Steam Dryer and Implementation of Extended Power Uprate
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.
Summary:
The Unit 3 Replacement Steam Dryer was inspected during the fall 2017 refueling outage, P3R21, from October 25th through November 1st 2017. This was the first refueling outage following installation of the RSD in November 2015, P3R20, and operation at Extended Power Uprate (EPU) conditions since 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 BWRVIP-139-A inspection locations and finally, by higher stress locations where solution annealing of structural welds had not been performed.
The guidelines for the dryer inspection are defined in WCAP-17635-P Section 5. Table 5-1 provides the inspection locations for the Unit 3 RSD following the first cycle of operation at EPU conditions. A general visual examination (VT-3) was performed on the entire RSD. The baseline inspection included the top of the RSD (including the outside of the skirt), underside of the RSD, lifting rods, outer ring top cage, W and U channel guides, support ring, vertical drain channels, and outer, middle and inner hoods. All observations were acceptable for the structural components and welds inspected. There were indications at three weld locations that required further evaluation. These welds are non-structural and were not explicitly modeled or analyzed as part of the structural qualWication of the steam dryer. The summary results of the inspections can be found in the table below.
NRI = No Relevant Indication RI= Relevant Indication Inspection Location Method Inspection Condition Report Disposition Result (If RI)
General Inspection of Top of the Replacement Steam Dryer (to include VT-3-89 NRI outside of skirt)
General Inspection on Underside of VT-3-89 NRI Replacement Steam Dryer Lifting Rods Top Ends (and welded attachments to the top plate of the VT-3-89, VT-1-89 NRI dryer)
Lifting Rods Top Ends (and welded VT-3-89, VT-1-89 RI 4069252 Use-as-is attachments to the support ring)
Support Ring VT-3-89 NRI Outer, middle, inner hoods VT-3-89 NRI Outer Ring Top Cage VT-3-89 NRI
Attachment - Results of Visual Inspection for PBAPS Unit 3 Replacement Steam Dryer Page 3of 7 Inspection Location Method Inspection Condition Report Disposition Result (if RI)
Vertical Drain Channels VT-3-89 NRI Skirt (Outside) VT-3-90 NRI Skirt (Inside) VT-3-91 NRI Visual examinations (VT-1-89) were performed on welds associated with the RSD. As described in WCAP- 17635-P, the steam dryer is octagonal (high symmetry) and VT-1-89 inspections were performed on a section of the octagon. If any flaws were identified, the comparable locations on the other sections of the dryer were examined in the same outage.
The results of the VT-1-89 inspections can be found in the table below:
Weld Designation Description Inspection Condition Report Disposition Result (if RI)
AA 365270 W 1 0 W channel to ring NRI AA 365270 W2 90 U channel to ring NRI Vertical drain channel AA 365270 W3 112.5 to ring NRI Upper Dryer to lower dryer circumferential AA 365270 W4 135 weld NRI Site Drain Channel AA 365270 W5 112.5 Piece Welds NRI Lifting rod bracket to AA 365270 W6 LR 142.25 top of dryer NRI Lifting rod bracket to AA 365270 W7 LR 142.25 ring connection RI 4069252 Use-as-is Lifting rod bracket to AA 365270 WB LR 142.25 rod NRI AA 365270 W9 LR 138.5 Lifting rod top to rod NRI AA 365270 W12 0 Vertical shim to block NRI AA 365270 W12 180 Vertical shim to block NRI Horizontal shims to AA 365270 W 14 90 block NRI Inner panel to inner AA 365271 W3 112.5 inner comer NRI Inner panel to inner AA 365271 W5 112.5 outer comer NRI Middle panel to AA 365271 W9 112.5 middle inner corner NRI
Attachment - Results of Visual Inspection for PBAPS Unit 3 Replacement Steam Dryer Page 4 of 7 Weld Designation Description Inspection Condition Report Disposition Result (If RI)
Middle panel to AA 365271 W11 112.5 middle outer comer NRI Top Inner hood to AA 365271 W13 90 inner panel NRI Inner hood to inner AA 365271W15112.5 hood NRI Outer panel to outer AA 365271 W18 112.5 inner comer NRI Outer panel to outer AA 365271W20112.5 outer comer NRI Outer comer top cap AA 365271 W21 112.5 all around NRI Top middle hood to AA 365271 W22 90 middle panel NRI Bottom middle hood AA 365271 W23 90 to outer panel NRI Middle hood to AA 365271 W24 112.5 Middle hood NRI Top outer hood to AA 365271 W26 90 outer panel NRI Bottom outer hood to AA 365271 W27 90 support ring NRI Outer hood to Outer AA 365271 W28 112.5 hood NRI Top ring girder to panel and corner and AA 365271 W29 112.5 Inner corner cap NRI Top ring girder to panel and corner and AA 365271 W29 112.5 Middle corner cap NRI Top ring girder to panel and corner and AA 365271 W29 112.5 Outer corner cap NRI Seismic Block (Outer AA 365271 W 30 90 2 Welds) NRI AA 365271 W32 90 Shims RI 4067519 Use-as-is AA 365271W32270 Shims NRI Seismic Block (Inner AA 365271 W33 90 2 Welds) NRI Middle corner to top AA 365271 W36 112.5 middle hood NRI Outer corner to top AA 365271 W37 112.5 outer hood NRI Two hal'A:!s of main AA 365274 W1 55 ring NRI Inner top channel to AA 365301 W5W8W18 90 top strip NRI Middle top channel to AA 365302 W5WBW18 90 top strip NRI
Attachment - Results of Visual Inspection for PBAPS Unit 3 Replacement Steam Dryer Page Sot 7 Weld Designation Description Inspection Condition Report Disposition Result (If RI)
Outer top channel to AA 365303 W5W8W18 90 top strip NRI Outer pert plate to top AA 365303 W 13 90 strip NRI AA 365311 W2 112.5 Girders to center ring NRI Middle ring to lower AA 365272 W 1 0 W channel NRI Middle ring to lower U AA 365272 W2 90 channel NRI Middle ring to lower AA 365272 W3 135 part outer walls NRI Middle ring to lower part vert drain AA 365272 W4 112.5 channels NRI Middle ring to upper AA 365272 W5 0 W channel NRI Middle ring to upper AA 365272 W6 90 U channel NRI Middle ring to upper AA 365272 W7 135 outer walls NRI W and U channels to AA 365272 W8 90 upper outer walls NRI Middle ring to upper AA 365272 W9 112.5 vert drain channels NRI Vert drain channels AA 365272 W10 112.5 to upper outer walls NRI W channel to lower AA 365284 W 1 0 ring NRI U channel to lower AA 365284 W2 90 ring NRI Lower ring to walls AA 365284 W3 135 above NRI Wand U channels to AA 365284 W4 90 walls NRI Drain channels to AA 365284 W5 112.5 walls NRI Lower ring to drain AA 365284 W6 112.5 channels NRI Welds Lower Ring AA 365286 W 1 45 Together NRI Middle ring welded AA 365285 W 1 45 together NRI
Attachment - Results of Visual Inspection for PBAPS Unit 3 Replacement Steam Dryer Page 6of 7 Inspection Results:
Indications were identified in weld AA 365270 W7 fillet weld at the lifting rod interface to the support ringfor two of the four (4) lifting rod locations at 142.25 and 322.25 degree azimuths and at the AA 365270 W9 fillet weld from the lifting lug to lifting rod interface on the lifting rod at 37.75 degree (Ref. IR 4069252). Similar indications were observed during examinations of the Unit 2 replacement steam dryer as documented in the 2016 Visual Inspections Results Letter (Ref. ML163428621, Letter from Exelon to NRG dated December 7, 2016, Results of Visual Inspections of Unit 2 Replacement Steam Dryer). Also, during examination of the steam dryer support shims, gouge marks on the face of the shim and FME wear were observed on weld AA 365271 W32 90 deg shim. The other shims had no recordable indications. The FME (scrapings and sliver) identified on the 90 deg shim was removed and no other loose material was identified (Ref. IR 4067519). All indications have been dispositioned as use-as-is. The indications do not adversely affect the steam dryer's structural integrity. The welds are non-structural and were not explicitly modeled or analyzed as part of the structural qualification of the steam dryer.
The IWting rod weld locations and shims are scheduled for re-inspection during the Unit 3 P3R22 in 2019 to determine W any changes have occurred. No other recordable indications were dentified during the inspection process.
Disposition of Indications:
During P3R21, cracks were observed at the AA365270 W7 fillet weld at the lifting rod interface to the support ring for two of the four (4) hold down rod locations at 142.25 and 32225 degree azimuths as well as at the AA365270 W9 fillet weld from the lifting lug to lifting rod interface on the lifting rod at 37.75 degree. Gouge marks and FME wear were also observed on the shim at weld AA365271 W32 at 90 deg. The FME was retrieved and the other shims had no recordable indications.
The non-structural fillet welds (AA365270 W7 and W9} of the lifting rod are for positioning and anti- rotation during construction. In that function, as construction welds, they do not carry primary load. The lifting rod function does not depend on the non-structural AA365270 W7 and W9 fillet welds. During plant operation, the positioning at the top and bottom of the lifting rod is guaranteed by the threaded portions of the lifting rod; and the anti-rotation is maintained by the top bracket and its structural hold down rod top to rod AA 365270 wa weld.
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 this weld in the inspection plan was primarily due to its 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 lifting rod attachment to the ring is the integrity of the threaded connection at the ring attachment location. The inspection has confirmed no crack extension into the rod, and no crack extension into the rod is anticipated.
The top bracket with its structural weld AA365270 W8 maintains position, prevents rotation and assures thread engagement, thus eliminating any risk for loose parts. The design stress margins for the top bracket remain unchanged by the cracking of the construction fillet welds at the bottom support ring location.
Attachment - Results of Visual Inspection for PBAPS Unit 3 Replacement Steam Dryer Page lot 7 No repair is required to the non-structural welds at the top and bottom of the lifting rods.
The AA365270 W7 and W9 locations will be re-inspected during P3R22 to confirm no crack extension into the lifting rod at the ring attachment location or crack initiation at the upper bracket welds. The AA365271 W32 location will also be re-inspected during P3R22 to determine if additional gouge marks or wear are apparent.
The lifting lugs for PBAPS Unit 3 have two functions: (1) dryer installation lifting operation, and (2) hold- down of the dryer during faulted condition load and possible lifting of the dryer. These conditions do not impact the I ifting rods (LR) ability to perform their function.
No linear indications (fatigue or IGSCC cracks) were identified on any of the lifting rod assemblies. As such, there is no degradation mechanism present that could impact the integrity of the attachment weld to the top of the LR bracket, or the integrity of the LR ~self .
==
Conclusion:==
A complete baseline inspection of the Peach Bottom Unit 3 Steam Dryer was performed during the fall 2017 refueling outage 21. The baseline inspection included successful visual inspection of all of the inspection locations required by the Facility Operating License Condition 2.C(15)(f) for inspection of the Replacement Steam Dryer. All observations were acceptable for the structural components and welds inspected. There were three non-structural welds found with cracks and one shim found with marks/ wear that were dispositioned acceptable as-is. The welds were not explK;itly modeled or analyzed as part of the structural qualification of the dryer. The subsequent inspection scope of the steam dryer will be performed during the Unit 3 P3R22 outage in 2019 and the results will be provided at that time consistent with the Peach Bottom Operating License.