ML12089A491
| ML12089A491 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/05/2012 |
| From: | Shea J W Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC ME7225 | |
| Download: ML12089A491 (14) | |
Text
Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402March 5, 201210 CFR 50.410 CFR 50.90ATTN: Document Control DeskU.S. Nuclear Regulatory CommissionWashington, D.C. 20555-0001Sequoyah Nuclear Plant, Unit 1Facility Operating License No. DPR-77Docket No.50-327Subject:Reference:Response to NRC Second Request for Additional InformationRegarding the Heavy Load Lifts and UHS One Time Change inSupport of Unit 2 SGRP (TAC NO. ME7225)1. Letter from TVA to NRC, "Application to Revise Sequoyah NuclearPlant, Unit 1, Operating License and Technical Specification 3.7.5,"Ultimate Heat Sink," to Support Sequoyah Nuclear Plant, Unit 2,Steam Generator Replacement Project (TS-SQN-2011-05)," datedSeptember 29, 20112. Electronic Mail from NRC to TVA, "Sequoyah, Unit 1 LAR -HeavyLoad Lifts and UHS One Time Change in Support of Unit 2 SGRP(TAC NO. ME7225)," dated January 13, 20123. Letter from TVA to NRC, "Response to NRC Request for AdditionalInformation Regarding the Heavy Load Lifts and UHS One TimeChange in Support of Unit 2 SGRP (TAC NO. ME7225), datedFebruary 10, 20124. Electronic Mail from NRC to TVA, "Sequoyah, Unit 1 LAR -HeavyLoad Lifts and UHS One Time Change in Support of Unit 2 SGRP(TAC NO. ME7225)," dated February 2, 2012By letter dated September 29, 2011 (Reference 1), the Tennessee Valley Authority(WVA) submitted a one-time request for amendment to the Operating License (OL) forSequoyah Nuclear Plant (SQN), Unit 1. The amendment request proposed to add aone-time license condition to the SQN, Unit 1, OL for the conduct of heavy load liftsPrinted on recycled paper7~c5~0 U.S. Nuclear Regulatory CommissionPage 2March 5, 2012associated with the SQN, Unit 2, Steam Generator Replacement Project (SGRP).The one-time license condition establishes special provisions and requirements forthe safe operation of SQN, Unit 1, while large heavy load lifts are performed on SQN,Unit 2. In addition, a one-time change to SQN, Unit 1, Technical Specification (TS)3.7.5, "Ultimate Heat Sink," is also proposed to implement additional restrictions withrespect to maximum average Essential Raw Cooling Water System supply headerwater temperature during large heavy load lifts performed to support the SQN, Unit 2,SGRP.By electronic mail dated January 13, 2012, (Reference 2), the NRC forwarded arequest for additional information (RAI) regarding the proposed changes establishingthe special provisions and requirements for large heavy load lifts on SQN, Unit 2.TVA responded to this first RAI by letter dated February 10, 2012 (Reference 3).Subsequently, in an electronic mail dated February 2, 2012, the NRC forwarded asecond RAI regarding the proposed changes and requested a response within 30days. The enclosure to this letter provides TVA's response to the second RAI. Asdiscussed in the response to Question 2 of the enclosure to this letter, a change wasmade to Figure 6-1 of Enclosure 2 to the Reference 1 letter. No other changes havebeen made to the license amendment request of Reference 1 or to the first RAIresponse of Reference 3.There are no regulatory commitments included in this submittal. If you have anyquestions, please contact Clyde Mackaman at (423) 751-2834.I declare under penalty of perjury that the foregoing is true and correct. Executed onthe 5th day of March 2012.Res tfully,4SheaMaager, Corporate Nuclear LicensingEnclosure:Response to NRC Second Request for Additional Information Regarding theHeavy Load Lifts and UHS One Time Change in Support of Unit 2 SGRPcc (Enclosures):NRC Regional Administrator -Region IINRC Senior Resident Inspector -Sequoyah Nuclear PlantDirector, Division of Radiological Health, Tennessee State Department ofEnvironment and Conservation ENCLOSURETENNESSEE VALLEY AUTHORITYSEQUOYAH NUCLEAR PLANTUNIT 2RESPONSE TO NRC SECOND REQUEST FOR ADDITIONAL INFORMATIONREGARDING THE HEAVY LOAD LIFTSAND UHS ONE TIME CHANGE IN SUPPORT OF UNIT 2 SGRPNRC Question 1Background:Although they are simple schematics, Figures 6-1 and 8-2 both show the isolation boundaryvalve of the 2B essential raw cooling water (ERCW) header (2-FCV-67-82) to be outside theboundary of the Auxiliary Building and adjacent to the potential drop zone.Issue:The application does not assume that the isolation function of the subject valve could potentiallybe impacted by the postulated drop; however, the valve is clearly shown to be outside of theAuxiliary Building and adjacent to the potential drop zone. Following a postulated drop, if2-FCV-67-82 is, in fact, in the ERCW tunnel and could be affected by a heavy load drop, theisolation function would be negated and, via the cross-tie, the lB header would be dischargingthrough the broken end of the 2B header. This would critically change flow and heat loadcalculations in the cross-tied configuration and potentially cause massive flooding of the ERCWtunnel.Request:Please provide a detailed description of the physical location of ERCW system valve,2-FCV-67-82, with respect to the potential drop zone of a heavy load. If 2-FCV-67-82 is in thepotential drop zone, describe how the ERCW 2B header will be isolated.TVA ResponseValve 2-FCV-67-82, along with its companion valve 2-FCV-67-81, are located at the entrance tothe pipe tunnel from the Auxiliary Building. The valves are inside the pipe tunnel, but outside ofthe tunnel area to be enclosed by the temporary wall as shown on Figure 8-1 of TechnicalReport No. SQN2-SGR-TR1 submitted in Reference 1. These valves are outside of thepostulated load drop zone. Figure 1 of this enclosure outlines the location of the valves withrespect to the potential drop zone of a heavy load on Figure 6-2 of Technical Report No.SQN2-SGR-TR1 submitted in Reference 1. Figures 2 and 3 of this Enclosure provide additionaldetails of the valve locations as taken from SQN drawing nos. 1, 2-41 N700-2, "ConcreteGeneral Outline Features," and 1, 2-47W850-8, "Mechanical ERCW."E-1 NRC Question 2Background:The application refers several times to essential cross-tie valves with unique identifiers:O-VLV-67-1610, -1611, -1612, and -1613. These valves are presumed to be shown (althoughnot labeled as such) in Figures 6-1 and 8-2 on the 16-inch piping labeled as "Aux Bldg HeaderCrosstie."Issue:The subject valves are not shown on the latest UFSAR Figure 9.2.2-2 for the ERCW system,nor does the application identify them as temporarily installed equipment.Request:Please provide an explanation for the absence of the ERCW header cross-tie valvesO-VLV-67-1610, -1611, -1612, and -1613 from UFSAR Figure 9.2.2-2. Also, provide an updatedFigure 6-1 showing where these valves are located or accurately describe the location of thesevalves on Figure 6-1.TVA ResponseThe valves and cross-tie lines were installed under Design Change Request (DCN) 21894. TheDCN indicated Updated Final Safety Analysis Report (UFSAR) Figure 9.2.2-2 was to beupdated to include the changes. The UFSAR update for these DCN changes was notprocessed appropriately and, consequently, had not been incorporated into the UFSAR. TVAhas taken the required actions to include this drawing revision in Amendment 24 to the UFSAR.This issue was recorded in TVA's Corrective Action Program.Attachment 1 of this enclosure provides a full size, updated UFSAR Figure 9.2.2-2 with thecross-tie valves indicated. Figure 4 of this enclosure provides an updated Figure 6-1 asrequested, with the valve numbers for the cross-tie valves added to accurately depict theirlocation.E-2 NRC Question 3Background:Due to the temporary alignment of the ERCW system to accommodate the mitigation strategyfor the potential drop of a heavy load, the subject amendment requests to lower the requiredaverage water temperature of the ERCW system header from 87 degrees F to 74 degrees F.This new temperature value is the result of a steady-state hydraulic analysis of the ERCWsystem.Issue:Although the resulting 74-degree F value is requested by the subject application, there is nodescription of the design inputs and assumptions of the calculation which determined this newnumber.Request:Please describe the changes in the design inputs and assumptions of the new hydraulicanalysis from the current hydraulic analysis. Explain why the maximum allowed ERCW systemheader temperature changes from 87 degrees F to 74 degrees F.TVA ResponseThe current hydraulic analysis provided the basis for the new hydraulic analysis.For the new hydraulic analysis, the component alignments in the current hydraulic analysis werechanged to represent the ERCW system alignment required to assure a safe shutdown of SQN,Unit 1 during Steam Generator Replacement Project (SGRP) activities on SQN, Unit 2. Thus,the new hydraulic analysis uses the same modeling methodology and calculation methods asthe current hydraulic analysis and the design inputs and assumptions are consistent. As aresult of the postulated heavy load drop described in the submittal (Reference 1 of the coverletter), a system alignment change for the prerequisite valve alignment was necessary due tothe considerations for damage to the ERCW 'B' discharge piping. This change resulted in theneed to lower the Ultimate Heat Sink temperature because of a worst case reduction in flow rateto the most limiting component of approximately 38 percent.The results of the hydraulic calculation would not support the required flow rates for the fulldesign basis Ultimate Heat Sink temperatures, so a thermal calculation change was preparedthat determined the appropriate Ultimate Heat Sink limitation at which the required heattransfer/equipment cooling would be accomplished for the affected safety related components.The calculations established that, for the ERCW system alignment required to assure a safeshutdown of SQN, Unit 1, during SGRP activities on SQN, Unit 2, the ERCW system canperform its safety function subject to a maximum ERCW supply temperature of 75.6 degrees F.This was rounded down to 74 degrees F, for conservatism.E-3 NRC Question 4Background:Due to the temporary alignment of the ERCW system to accommodate the mitigation strategyfor the potential drop of a heavy load, the subject amendment requests to lower the requiredaverage water temperature of the ERCW system header from 87 degrees F to 74 degrees F.Issue:Quantifying the historical average temperature of the water in the ERCW header will provide abenchmark by which the Nuclear Regulatory Commission staff can establish a realistic marginbetween the water temperature which will be technically required and that which is likely to beprovided.Request:Please provide a summary of the last five years historical data which shows the actual, averagetemperature of the water in the ERCW header during the approximate time of year when thesubject heavy load lifts are scheduled to be performed. (e.g. From October XX to November XXof 20XX, the average temperature of the ERCW header water was XX degrees. etc.)TVA ResponseBy the preliminary outage schedule, the unit shutdown will be on October 15, 2012. The coreoffload is scheduled to complete October 22, 2012, with the first heavy load lift soon thereafter.The last heavy load lift is scheduled to completed by November 20, 2012. From October 15 toNovember 20, the average ERCW temperature as measured at the intake for the followingyears was:YEAR AVERAGE TEMP2011 63.4 degrees F2010 64.0 degrees F2009 63.9 degrees F2008 63.9 degrees F2007 65.8 degrees FIn addition, Figure 5 of this Enclosure provides the historical SQN ERCW intake temperaturesfor the period of October 15 to November 20 for the years 1981 through 2011. This graphdepicts the median, average, minimum, maximum, average minus standard deviation andaverage plus standard deviation temperatures of the water at the ERCW intake.E-4 FIGURE 1Location of Valves with Respect to the Drop ZoneFigure 6-2 -Heavy Load Lifting Postulated Drop ZoneTechnklca Report No. SON2-SGR-TR IPage 53 of 9gE-5 00/ CD &.~'0CO)I ~Valves 2-FCV-67-81 and -82 10zli_ ----00AS zJ0 *~ m .
Column line Al 5 is the AuxiliaryBuilding outside wallam!~~~~A up 2-'2'026"-0*DOG 1793001510o SM WT PIPEBRSL EEVE MY FIELD)'3 / -! 4- EL51-3-187 "-0IiLA* 4LEL 687'-0' ;j 14FV TE -~ 3-01 --l 7-425- ~ ~ r 5 1130- 7 7- 5 *9111-0062I-521-62 -.T!ilI -T-0658i,m-!4IT060 95 m19--0361 ) 1 i 3CNO1C5 ON.l~ 135105 35AC108 ..,rr..r 82tn0co)0z0-9cwC4Valve 2-FCV-67-82Located HerePLAN EL 669.0512 aM0C,)0z03G)m'In40cnfag0)r00)CLZ! a~ccTu2.CDw FIGURE 5SEQUOYAH ERCW INTAKE TEMPERATURES 1981-2011UPDATE 12/3111180.0078.0076.0074.0072.0070.0068.00.-.66.001-62.0060.0058.0056.0054.0052.0050.00C,,,-Median-Average-MinimumTemp-MaximumTemp-Average -Std Dev-Average +Std DevhDATpDATEJE-9 ATTACHMENT 1UFSAR Figure 9.2.2-2E-1O (insert full size UFSAR Figure 9.2.2-2)E-11 THIS PAGE IS ANOVERSIZED DRAWING ORFIGURE,THAT CAN BE VIEWED AT THERECORD TITLED:"FIGURE 9.2.2-2ESSENTIAL RAW COOLINGWATER SYSTEM(REVISED BY AMENDMENT 24)WITHIN THIS PACKAGED-01