ML20181A308
| ML20181A308 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 06/23/2020 |
| From: | Mladen F Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 20-240 | |
| Download: ML20181A308 (11) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 JUN23,2020 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNIT 1 Serial No.:
20-240 SPS LIC/MMT RO Docket No.:
50-280 License No.:
DPR-32 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION 2019 STEAM GENERATOR INSERVICE INSPECTION REPORT By letter dated March 11, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20087H009), Virginia Electric and Power Company (Dominion Energy Virginia) submitted information summarizing the results of steam generator (SG) tube inspections performed at Surry Power Station Unit 1 during the fall 2019 refueling outage. On June 4, 2020, the NRC requested additional information related to the SG inspections. The NRC's question and Dominion Energy Virginia's response are provided in the attachment to this letter.
If you have any questions or require additional information, please contact Mr. Michael True at (757) 365-2446.
Respectfully, Fred Mladen Site Vice President Surry Power Station Attachment - Response to NRC Request for Additional Information Regarding Fall 2019 Steam Generator Tube Inspection Report - Surry Power Station Unit 1 Commitments made in this letter: None
cc:
U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303 Mr. Vaughn Thomas - Surry NRC Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 04 F-12 11555 Rockville Pike Rockville, Maryland 20852 Mr. G. Edward Miller - North Anna NRC Sr. Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, Maryland 20852 NRC Senior Resident Inspector Surry Power Station Mr. R. A. Smith Authorized Nuclear Inspector Surry Power Station Serial No.: 20-240 Docket No.: 50-280 Page 2 of 2
ATTACHMENT Serial No.: 20-240 Docket No.: 50-280 Response to NRC Request for Additional Information Regarding Fall 2019 Steam Generator Tube Inspection Report Surry Power Station Unit 1 Virginia Electric and Power Company (Dominion Energy Virginia)
Serial No.: 20-240 Docket No.: 50-280 Attachment RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING SURRY UNIT 1 FALL 2019 STEAM GENERATOR TUBE INSPECTIONS NRC Comment By letter dated March 11, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20087H009), Virginia Electric and Power Company (the licensee) submitted information summarizing the results of the fall 2019 steam generator tube inspections performed at Surry Power Station (Surry), Unit 1.
These inspections were performed during refueling outage (RFO) 29. Technical Specification (TS) 6.6.A.3 requires that a report be submitted within 180 days after Tavg exceeds 200°F following completion of an inspection of the SGs performed in accordance with TS 6.4. Q, "Steam Generator (SG) Program."
To complete its review of the inspection report, the U.S. Nuclear Regulatory Commission staff requests the following additional information:
- 1. Please clarify the sampling strategy for eddy current examination of features such as dents, dings, and bulges in the Surry Unit 1 SGs. Table 1, "Inspection Method for Applicable Degradation Modes," of the inspection report lists the methods used for inspections, but the report does not identify how inspection methods were applied to some special interest features (for example, the selection criteria for examination of dents and dings with specialized probes).
Response
An eddy current examination is performed on each steam generator at Surry Power Station every other refueling outage. The in-service tube base scope includes a 100%
bobbin probe exam, 100% array probe exam of the top-of-tubesheet on both the hot-leg and cold-leg (including all overexpansions within the tubesheet down to the H* distance),
100% full length array probe of all "Tier 1" tubes identified with potentially high residual stress, and a +Point' exam of all over rolls (4), bulges (3), and low row (row 1 and 2) U-bends.
In addition to the base scope, a preplanned special interest scope was developed, which includes a sample of previously identified dents, dings, manufacturing burnish marks, volumetric indications, and wear (excluding AVB wear). In total, 162 special interest locations were preplanned to be examined using specialized probes and diagnostic techniques.
The specific dent/ding scope included fifty percent of previously identified dents/dings >2 Volts located in hot-leg straight sections (TSH +0.00 to 07H+1.00"), plus any additional Page 1 of 8
Serial No.: 20-240 Docket No.: 50-280 Attachment indications required to ensure that the five largest voltage dents/dings in hot-leg straight sections are included in the sample. Also, the five largest voltage dents/dings located between the cold-leg tubesheet and the straight section of the hot-leg, (between TSC and 07H+1.01 ") are included in the preplanned scope.
There were 116 in-service tubes with 137 dent/ding indications measuring > 2 Volts on the hot-leg straight section in SG-B reported in 1 R27. A 50% sample yields 69 indications for inspection.
Fifty-seven (57) indications were not inspected in 1 R27 and were preplanned for inspection with +Point' probe during the 1 R29 outage. The five largest dents (by voltage) were also included in the sample for inspection. Additional indications from 1 R27 were selected to maintain the 50% minimum sample requirement. A total of 70 dent indications in 65 tubes were scheduled for testing.
During the examination, indications are detected including permeability variations, deposits, possible loose parts signals, and ambiguous or anomalous indications, which require additional categorization with diagnostic techniques.
These indications are examined with a +Point' probe. The total special interest scope in SG-B during 1 R29 was 219 indications.
- 2. With respect to the secondary-side inspections, please clarify for each SG whether foreign objects or loose parts were removed, and the number and type of objects removed.
Response
Surry Power Station has recently escalated efforts to remove all foreign objects from the secondary side of the steam generators. Several foreign objects were removed from each of the three Surry steam generators during 1 R29 via water lancing or foreign object search and retrieval activities. Some enhanced, localized in-bundle lancing was also performed to aid in these removal efforts. A description of the foreign objects removed from the Surry steam generators is contained in Table 1.
- 3. Table 3, "Surry 1 EOC29 Inspection Summary-Non-A VB Volumetric Degradation," of the inspection report, which lists non-antivibration bar volumetric degradation, includes an indication in tube Row 33 Column 17, which the staff did not find in previous inspection reports. Please clarify whether this is a legacy indication or a newly reported indication that may be a result of recent degradation. If there is evidence of recent degradation, please discuss if a loose part may still be present. The staff notes that nearby tubes have previously reported loose part indications but without evidence of a loose part remaining.
Page 2 of 8
Response
Serial No.: 20-240 Docket No.: 50-280 Attachment The indication in Surry Unit 1 SG-B, tube R33 C17 at structure BPH has been reported by bobbin as a Distorted Support Signal (DSS) since 2010. DSS indications receive a special interest inspection with either or both Motorized Rotating Pancake Coil (MRPC) and Array at each inspection. The result of the special interest inspections has consistently been No Degradation Found (NDF), Indication Not Recordable (INR), or in one case, X-Probe Signal (XPS). In the 2019 inspection the Lead Level Ill chose to report the indication as wear (WAR) and estimated the depth at 15% TW using EPRI technique 27901.1. This was a conservative decision based on industry experience of fretting wear from foreign material on the secondary side, the indication's location relative to the structure and the signal's appearance, and response to the various inspection probes. The subject indication is very shallow resulting in varying degrees of detection over the past inspections and shows no change since the 2010 inspection.
The area around this tube was thoroughly examined visually to confirm that no foreign object remains at this location.
Page 3 of 8
SG-Item#
Description Historical (1R24) cluster of A-4 fine wire and sludge at TSH (1R29) Irregular shaped A-11 object at TSC A-12 (1R29) Round object at TSH
( I R29) Irregular shaped A-14 object at TSH A-15 (1 R29) Flake at TSC A-16 (1 R29) Scale at TSC (IR29) Irregular shaped A-17 object at TSC
( l R29) Irregular shaped A-18 object at TSC
( I R29) Irregular shaped A-19 object at TSC (IR29) Round object A-20 atTSH A-23
( I R29) Irregular object at TSH Table 1: Foreign Objects Removed During 1 R29 Location Configuration ECT Results Estimated Size Fixity Rl4-C49 Legacy cluster of fine wire ECT not Not Removed and sludge located at TSH performed during Rl4-C50 behind the center tie-rod during IR29 Determined lancing R14-C4 Irregular shaped object ECTnot 0.75" X 0.38" X RI4-C5 discovered at TSC during performed 0.38" Retrieved post lance SSI during I R29*
R27-CI4 Round object discovered at ECT not 0.63" X 0.44" X R26-Cl4 TSH during post lance SSI performed 0.44" Retrieved during 1R29 R40-C44 Irregular shaped object ECTnot 0.81" X 0.44" X discovered at TSH during performed Retrieved R40-C45 post lance SSI during lR29 0.38" R42-C31 Flake discovered at TSC ECTnot LO" x 0.38" x R42-C30 during post lance SSI performed 0.06" Retrieved R43-C31 during 1R29 R44-C37 Piece of scale discovered at ECTnot 0.50" X 0.38 X R44-C36 TSC during post lance SS!
performed 0.06" Retrieved R43-C36 during IR29 Irregular shaped object ECTnot 0.50" X 0.31" X R44-C38 discovered at TSC during performed Retrieved post lance SSI during IR29 0.06" R45-C44 Irregular shaped object ECTnot 0.56" X 0.44" X discovered at TSC during performed Retrieved R45-C45 post lance SSI during IR29 0.06" R46-C46 Irregular shaped object ECTnot 0.63" X 0.38" X discovered at TSC during performed Retrieved R46-C45 post lance SSI during 1R29 0.06" R2-C93 Round object discovered at ECTnot 0.50" X 0.44" X performed Retrieved R3-C93 TSH during post lance SSI during lR29 0.44" R39-C65 Irregular shaped object ECTnot R38-C65 discovered at TSH during performed 0.40"x0.40"x Retrieved R38-C64 post lance SSI during IR29 0.30" R39-C64 Page 4 of 8 Serial No.: 20-240 Docket No.: 50-280 Attachment 2019 Disposition Legacy cluster of fine wire was removed during IR29 TTS lancing.
During I R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During 1R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during removal process.
During 1 R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During lR29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During I R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During IR29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During 1 R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During 1R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During lR29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During 1R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
SG-Item#
Description Location Configuration ECT Results (I R29) Irregular object at R4-C83 Irregular shaped object ECT not A-24 discovered at TSH during performed TSH R4-C82 post lance SSI during IR29 (IR29) Irregular object at Rl-C74 Irregular shaped object ECT not A-25 discovered at TSH during performed TSH RI-C75 post lance SSI during IR29 Parts captured in the lancing A-27 (1R29) Lancing strainer parts TTS strainers during I R29 TIS NIA lancing
- '.\\t\\'::x**<" :_,: :.,...
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R31-Cl5 /
BPH +0.54 R31-Cl6 I Historical (IR21) BPH wear BPH+0.51 locations.
R32-Cl5 I Historical foreign object (JR29) PLP BPH+0.54 wear on the H/L side of the WAR B-1 baffle plate R33-CJ8 BPH+0.54 R32-Cl8 I New PLP and WAR at PLP (IR29) WAR BPH+0.55 IR29 R33-Cl7 BPH+0.61 R33-Cl8 /
BPH+0.66 R35-C20 I BPH+l.13 Historical (IR27) Lodged R39-C26 B-7 round object at TSH was R39-C27 Foreign object was retrieved NOD retrieved (IR29). Likely hard R40-C26 prior to performing ECT sludge.
R40-C27 (IR29) Irregular object at R43-C52 Foreign object was retrieved B-11 NOD TSH. Likely hard sludge.
R43-C53 prior to performing ECT Parts captured in the lancing 8-14 (1R29) Lancing strainer parts TTS strainers during IR29 TIS NIA lancing Page 5 of 8 Estimated Size Fixity 0.75" X 0.38" X Retrieved 0.40
No measurement Retrieved taken Various parts ranging from Removed
- I/8" to -1/2"
- -,,;,
- ; }";;,','::,; i',':i,:\\(+
Scale pulled NIA back but broke apart 0.4" diameter Retrieved 0.5" X 0.5" X Retrieved 0.15" Various parts ranging from Removed
-118" to -1/2" Serial No.: 20-240 Docket No.: 50-280 Attachment 2019 Disposition During I R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During l R29 object was both discovered and retrieved from the SG. SSI noted no tube damage during retrieval process.
During IR29, many objects were captured in the SG A lancing strainers.
Most are sludge related. There were also fragments of small diameter wire and flex gasket material.
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IR29 wear not newly developed, rather newly reported. Wear (R33-CI 7) was present IR23 and IR25. PLP (R33-Cl8) due to loose scale adjacent to tube. Scale pulled back but broke apart. No potential for wear growth going forward.
Continue to monitor with ECT affected and bounding tubes (bounding of plugged and in-service tubes with wear).
During 1R29, object was retrieved prior to ECT. Array results were INF and NOD for affected and bounding tube.
During IR29, object was retrieved prior to ECT. Array results were NOD for affected and bounding tubes.
During IR29, many parts were captured in the SG B lancing strainers. Most were sludge related. There were also fragments of flex gasket material.
SG-Item#
B-16 Description (I R29) Array PLPs (three tubes) confirmed with +Point Location R25-C31 I TSC+2.23" R26-C31 I TSC+l.74" R27-C32 I TSC+l.17" I ;'.'\\i;> q::,F;',{,
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- ,*.*: :,;;:'.:1:~:::... :. '* ***.
RI-C48 /
C-2 I Historical (I R20) hard I
TSH sludge Rl-C47 /
TSH R30-C48 C-28 I ( l R29) Ring shaped object at I R30-C49 TSC R31-C48 R3 I-C49 C-29 I ( 1 R29) Soft sludge rock at R40-C47 TSC R40-C48 (I R29) Small strip R43-C54 C-30 I resembling flex gasket R44-C54 covered in sludge at TSC C-31 I ( I R29) Hard sludge at TSC R44-C60 C-32 I (I R29) Hard sludge at TSH I R42-C51 R42-C52 R42-C49 C-33 I (1 R29) Soft scale at TSH I R43-C49 C-34 I (1R29) Hard sludge/ scale at I R42-C46 TSH R43-C46 Configuration ECT Results I Estimated Size Array PLPs (at TSC) confirmed with +Point.
Confirmed as a wire.
Referred to previously as "debris" but it is actually hard deposit material between the affected tubes.
The material was removed by sludge lancing Ring shaped object resembling the skeleton of a hex nut at TSC Sludge rock that disintegrated (C/L) during retrieval attempt. Debris remains in the SG Objects resembles a small piece of flex gasket covered in sludge at TSC Hard sludge found near the annulus at TSC Hard sludge found at TSH Scale retrieved from SG and broke apart, in hand, outside the SO Hard sludge found at TSH PLP (Array)
PLP (+Point)
No wear ECT not performed during 1R29 ECTnot performed during 1R29 ECTnot performed during IR29 ECTnot performed during 1R29 ECTnot performed during 1R29 ECT not performed during 1R29 ECT not performed during IR29 ECTnot performed during 1R29 Page 6 of 8 I
Wire 3.8" X 0.1" NIA 0.8"x 0.25" Disintegrated 0.3" X 0.2"X 0 ?"
0.3" X 0. 15" X 0.15" 0.4" X 0.25" X 0.15" Broke apart 0.15"x0.15" Fixity Serial No.: 20-240 Docket No.: 50-280 Attachment 2019 Disposition Small diameter wire was retrieved from Retrieved I tube locations with PLP. No associated wear. No future threat to tube integrity.
I R d I P"'1-l~<iag, the depositioa w~ ao emove via slud e long_er present. _Tubes _have been 1
. g routinely examined with no wear ancmg identified.
Object was retrieved during I R29 pre-Retrieved lance inspection. No evidence of tube damage identified by SSL Broke Sludge rock disintegrated during pre-apart during lance retrieval attempt. Poses no threat to retrieval tube integrity going forward.
Object was retrieved during 1R29. No Retrieved evidence of tube damage identified by SSL Sludge was retrieved during 1R29. No Retrieved evidence of tube damage identified by SSL Sludge was retrieval during IR29. No Retrieved evidence of tube damage identified by SSL Scale was retrieved and subsequently Retrieved broke apart outside the SG. Poses no threat to tube integrity going forward.
Sludge/scale was retrieved during IR29.
Retrieved No evidence of tube damage identified by SSL
SG-Item#
Description Location Con figuration ECT Results
( I R29) Hard sludge/ scale at R44-C36 Hard sludge / scale found at ECT not C-35 performed TSC R44-C37 TSC during IR29 RI-C6 Round shaped object ECT not C-36
( I R29) Round object at TSH R2-C6 resembling hard sludge at performed TSH during IR29 Parts captured in the lancing C-39 (IR29) Lancing strainer parts TTS strainers during I R29 TTS NIA lancing (IR29) Semi-circular shaped RI-C43 Semi-circular shaped object ECT not C-40 object at TSH. Likely hard R2-C44 identified during post lance performed sludge.
FOSAR.
during IR29 Small wire with one end ECTnot C-44 (IR29) Small wire at TSH R6-C29 embedded in hard collars at performed TSH during IR29 (IR29) Hard sludge rock at R43-C45 Hard sludge rock found at ECTnot C-45 performed TSH R44-C45 TSH.
during IR29 Page 7 of 8 Estimated Size Fixity 0.55" X 0.25" Retrieved 0.55" X 0.45" X 0.40" Retrieved Various parts ranging from Removed
-1/8" to -1/2" 0.50" X 0.50" X 0.25" Retrieved 1.15" Retrieved 0.60" X 0.30" X Retrieved 0.30" Serial No.: 20-240 Docket No.: 50-280 Attachment 2019 Disposition Sludge/scale was retrieved during IR29.
No evidence of tube damage identified by SSL Object was retrieved during IR29. No evidence of tube damage identified by SSL During IR29, many objects were captured in the SG C lancing strainers.
Most are sludge related. There were also fragments of small diameter wire and flex gasket material.
Object was retrieved during IR29. No evidence of tube damage identified by SSL Object was retrieved during IR29. No evidence of tube damage identified by SSL Sludge rock was retrieval during IR29.
No evidence of tube damage identified by SSL
Serial No.: 20-240 Docket No.: 50-280 Attachment ABBREVIATIONS AND ACRONYMS AILPC Accident Induced Leakage Performance Criteria ARC Alternate Repair Criteria AVB Anti-Vibration Bar BET Bottom of Expansion Transition BLG Bulge BOC Beginning Of Cycle BPC Baffle Plate Cold BPH CDS CM CMOA DA DDH DOI DDS Baffle Plate Hot Computer Data Screening Condition Monitoring Assessment Condition Monitoring and Operational Assessment Degradation Assessment Distorted Dent History Distorted Dent w/lndication Distorted Dent Signal DMT Deposit Minimization Treatment ONT Dent ECT Eddy Current Test EFPY Effective Full Power Years EOC End Of Cycle ETSS Examination Technique Specification Sheet F AC Flow Assisted Corrosion FOB Flow Distribution Baffle FK Foreign Object Tracking System Key FOSAR Foreign Object Search And Retrieval FOTS Foreign Object Tracking System GPO Gallons Per Day HRS High Residual Stress INF Indication Not Found INR Indication Not Reportable LGV Local Geometry Variation LPM Loose Part Monitoring LPS MAA MBM NDF NOPD NTE QA ODSCC OVR Loose Part Signal Multiple Axial Anomaly Manufacturing Burnish Mark No Degradation Found Normal Operating Pressure Differential No Tube Expansion Operational Assessment Outer Diameter Stress Corrosion Cracking Over Roll OXP Over Expansion PARC Permanent Alternate Repair Criteria PDA Percent Degraded Area PIT Pit PLP Possible Loose Part POD Probability Of Detection PTE Partial Tube Expansion PVN Permeability Variation PWSCC Primary Water Stress Corrosion Cracking QDA Qualified Data Analyst REOC Replacement End Of Cycle RPC Rotating Pancake Coil (generic term for all rotating probes)
SAA Single Axial Anomaly SCC Stress Corrosion Cracking SG Steam Generator SIPC Structural Integrity Performance Criteria SSI Secondary Side Inspection TSC Tube Sheet Cold TSH Tube Sheet Hot TSP Tube Support Plate TTS Top of Tubesheet TW Through Wall VOL Volumetric Page 8 of 8