ML21180A405
| ML21180A405 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 06/29/2021 |
| From: | Lippard G Dominion Energy South Carolina |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| .21-234 | |
| Download: ML21180A405 (4) | |
Text
V.C.SummerNuclear Station QQ@Q jQQ Bradham Blvd& Hwy 215,Jenk.insville, SC 29065 Mailing Address:
M@
P.O. Box 88,Jenkinsville, SC 29065 DominionEnergy.com June29,2021 Document Control Desk Serial No.21-234 U.S.Nuclear Regulatory Commission VCSLIC/BAB/Rev O
Washington, DC20555 Docket No.50-395 License No.NPF-12 V
SUPPLEMENT TONRCREQUEST FOR ADDITIONAL INFORMATION REGARDING RF-25 STEAMGENERATOR TUBEINSPECTIONREPORT
References:
1 DESCLetter, "Special Report (SPR) 2020-002
- SteamGenerator TubeInspection Report,"
dated October 20,2020(ADAMS Accession No.ML20296A692) 2.E-mail fromNRCSenior Project
- Manager, Vaughn Thomas,"Summer, Unit1-Final RAlsfortheSGTubeInspection ReportReview,"
dated May11,2020(ADAMS Accession No.ML21131A040) 3.DESCLetter, "Response toNRCRequest for Additional Information Regarding RF-25SteamGenerator TubeInspection Report,"
dated June3,2021(ADAMS Accession No.ML21154A180)
InReference 1,DESCsubmitted a Technical Specification requiredreport related to steamgenerator inspections performed during theVirgil C.SummerUnit1 Twenty-Fifth Refueling Outage(RF-25).
InReference 2,theNRCStaff provided a request for additional information (RAI) regarding this report.
InReference 3,DESCsubmitted a
response totheRAI.OnJune22,2021,aclarification telephone call washeld between VCSNSandtheNRCregarding thesesubmittals.
Thisisa voluntary submittal to provide asummary ofthephonecall.
Theenclosure tothis letter provides asummary of that call.
Serial No.21-234 Docket No.50-395 Supplement toRAIRegarding RF-25SGReport Page2of2 Ifyouhave any questions orrequire additional information, please contact Mr.Michael Mooreat(803) 345-4752.
Sincerely, 157c For Geore
. Lippard Site VicePresident V.C.SummerNuclear Station Commitments contained inthis letter:None
Enclosure:
Supplement toNRCRequest for Additional Information cc:G.J.Lindamood
- Santee Cooper L Dudes
- NRCRegion II V.Thomas
- NRCProject Mgr.
NRCResident Inspector
Serial No.21-234 Docket No.:50-395 Supplement toRAlRegarding RF-25SGReport Enclosure Supplement toNRCRequest forAdditional Information Virgil C.SummerNuclear Station (VCSNS)
Unit1 Dominion EnergySouthCarolina, Inc.(DESC)
Serial No.21-234 Docket No.:50-395 Enclosure
-Supplement toRAIRegarding RF-25SGReport:
Page1of1 DESC SUPPLEMENT TONRCREQUEST FORADDITIONAL INFORMATION REGARDING VCSNSUNIT1RF-25STEAMGENERATOR TUBEINSPECTION REPORT Virgil C.Summer Nuclear Station(VCSNS) andtheNuclear Regulatory Commission (NRC) heldaclarification callonJune22,2021todiscussthe VCSNSRAIResponse regarding theSpring2020 Steam Generator(SG)
TubeInspection Report.
During the
- call, VCSNSprovided information regarding thecauseoftubedenting, theprevious and current deposit
- quantity, and evaluation methods regarding tubefatigue atthetop support plate.
VCSNSidentified that themost probable causeofthenewdents waselevated crossflow resulting fromflow restriction inthehotleg, primarily atthetoptwoTube Support Plates (TSP).
Theflow restriction was causedbydeposit accumulation inthe TSPflowbroaches.
Thisnewdenting identified inRF-24(Fall 2018) wasoneofthe primary reasons foremergent chemical cleaning inRF-25(Spring 2020).
Prior tothe RF-25chemical
- cleaning, theVCSNSSecondary Side DepositManagement Strategy (Maestro Evaluation),
provided anoptimistic deposit inventory of2,228lbs, best estimate deposit inventory of4,722lbs, anda pessimistic deposit inventory of7,217lbs.
Thesenumbers werebasedoneddycurrent depositmapping andcorrosionproduct transport estimates.
During RF-25, 4,048Ibsofsludge was removed fromtheSGsvia chemical cleaning andsludge lancing Postchemical cleaning eddy currentdeposit mapping identified 3,592lbsofdeposit inventory remaining.
VCSNSalsoidentified that aspecific evaluation fortube fatigue at the topsupportplate wasnotperformed.
Thenewdents identified inRF-24andRF-25 were small and ranged from2.04volts to3.98volts insize withnowearatthese locations.
The RF-25 Condition Monitoring Operational Assessment provided discussion that cross flow effects will lessen asaresult ofchemical cleaning andthat weargrowth rates and distributions ofwearscars will also lessen goingforward.