ML13254A065
| ML13254A065 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 09/06/2013 |
| From: | Shea J W Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EA-12-051, TAC MF0951, TAC MF1178 | |
| Download: ML13254A065 (20) | |
Text
Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402September 6, 201310 CFR 2.202ATTN: Document Control DeskU.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Watts Bar Nuclear Plant, Unit 1Facility Operating License No. NPF-90NRC Docket No. 50-390Watts Bar Nuclear Plant, Unit 2Construction Permit No. CPPR-92NRC Docket No. 50-391
Subject:
Response to NRC Request for Additional Information Related to OverallIntegrated Plan in Response to the Commission Order Modifying Licenseswith Regard to Requirements for Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051)
(TAC Nos. MF0951 and MF1178)
References:
- 1. NRC Order Number EA-1 2-051, "Issuance of Order to Modify Licenses withRegard to Reliable Spent Fuel Instrumentation,"
dated March 12, 20122. TVA Letter, "Tennessee Valley Authority (TVA) -Overall Integrated plan inresponse to the March 12, 2012, Commission Order Modifying Licenses withRegard to Requirements for Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051) for Watts Bar Nuclear Plant," datedFebruary 28, 20133. NRC Letter, "Watts Bar Nuclear Plant, Units 1 and 2 -Request for Additional Information Regarding Overall Integrated Plan in Response to theCommission Order Modifying Licenses with Regard to Requirements forReliable Spent Fuel Pool Instrumentation (Order Number EA-12-051)
(TAC Nos. MF0951 and MF1 178)," dated August 2, 2013The purpose of this letter is to provide the Tennessee Valley Authority's (TVA) response to theRequest for Additional Information (RAI) regarding the Watts Bar Nuclear Plant's (WBN) OverallIntegrated Plan submitted to Nuclear Regulatory Commission (NRC) pursuant to OrderEA-12-051, "Order Modifying Licenses with Regard to Reliable Spent Fuel PoolInstrumentation."
Printed on recycled paper U.S. Nuclear Regulatory Commission Page 2September 6, 2013On March 12, 2012, the NRC issued Order EA-12-051, which directed holders of operating licenses under Title 10 of the Code of Federal Regulations (CFR), Part 50, "Energy,"
to providefor reliable spent fuel pool indications and submit to the NRC for review an overall integrated plan (OIP), including a description of how compliance with the requirements described inAttachment 2 of the Order would be achieved, by February 28, 2013 (Reference 1). TVAsubmitted the OIP for WBN, Units land 2 on February 28, 2013 (Reference 2). OnAugust 2, 2013, the NRC issued an RAI regarding the OIP submitted by TVA for WBN, Units 1and 2 (Reference 3). The RAI requested a response be provided within 30 days of the date ofthe letter. Thirty days from the date of the Reference 3 letter falls on a Sunday and the following Monday is a holiday.
Therefore, the response is due September 3, 2013. An extension toSeptember 6, 2013, was requested and approved.
Enclosure 1 of this letter provides TVA's responses to the RAI submitted in Reference
- 3. Asnoted in response to RAI questions 2 -4, 7, 8, 10, and 11, the requested information is notcurrently available, but will be provided by October 31, 2013, after the spent fuel poolinstrumentation design has been completed.
Enclosure 2 provides a new commitment toprovide this information.
If you have questions regarding this matter, please contact Kevin Casey at (423) 751-8523.
I declare under penalty of perjury that the foregoing is true and correct.
Executed onthe 6th day of September 2013.Resp ully,J. .SteaVi ,e Prsident, Nuclear Licensing
Enclosures:
- 1. Response to NRC Request for Additional Information Related to Overall Integrated Plan in Response to the Commission Order Modifying Licenses with Regard toRequirements for Reliable Spent Fuel Pool Instrumentation
- 2. List of Commitments cc (Enclosures):
NRC Regional Administrator
-Region IINRR Director
-NRC Headquarters NRR Project Manager -Watts Bar Nuclear Plant, Unit 1NRR Project Manager -Watts Bar Nuclear Plant, Unit 2NRC Senior Resident Inspector
-Watts Bar Nuclear Plant, Unit 1 ENCLOSURE ITENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT, UNITS I AND 2RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION RELATED TO OVERALL INTEGRATED PLAN IN RESPONSE TO THE COMMISSION ORDER MODIFYING LICENSES WITH REGARD TO REQUIREMENTS FORRELIABLE SPENT FUEL POOL INSTRUMENTATION ENCLOSUREI
1.0 INTRODUCTION
By letter dated February 28, 2013 (Agencywide Documents Access and Management System(ADAMS) Accession No. ML 13063A440),
Tennessee Valley Authority (TVA) submitted anOverall Integrated Plan (OIP) in response to the March 12, 2012, U.S. Nuclear Regulatory Commission (NRC) Order modifying licenses with regard to requirements for Reliable Spent FuelPool (SFP) Instrumentation (Order Number EA-12-051; ADAMS Accession No. ML12054A679) for Watts Bar Nuclear Plant, Units 1 & 2. The NRC staff endorsed Nuclear Energy Institute (NEI)12-02 "Industry Guidance for Compliance with U.S. Nuclear Regulatory Commission (NRC)Order EA-12-051, to Modify Licenses with Regard to Reliable Spent Fuel Pool Instrumentation,"
Revision 1, dated August 2012 (ADAMS Accession No. ML 12240A307),
with exceptions asdocumented in Interim Staff Guidance 2012-03, "Compliance with OrderEA-12-051, Reliable SFP Instrumentation,"
Revision 0, dated August 29, 2012 (ADAMSAccession No. ML12221A339).
The NRC staff has reviewed TVA's February 28, 2013, response and determined the following Request for Additional Information (RAI) is needed to complete its Technical Review.2.0 LEVELS OF REQUIRED MONITORING The OIP states, in part, thatKey SFP water levels will be identified as follows:* Level adequate to support operation of the normal fuel pool cooling system-Indicated level on either the primary or backup instrument channel ofgreater than 26.3 feet above the top of active fuel seated in the storageracks based on a calculation demonstrating a water level that ensures pumpnet positive suction head (NPSH) is adequate for normal fuel pool coolingsystem operation.
- Level adequate to provide substantial radiation shielding for a personstanding on the SFP operating deck -Indicated level on either the primaryor backup instrument channel of greater than 10 feet (+/- 1 foot) above thetop of stored fuel seated in the storage racks based on NEI 12-02 Section2.3.2, bullet 1. This monitoring level ensures there is an adequate waterlevel to provide substantial radiation shielding for a person standing on theSFP operating deck.0 Level where fuel remains covered -Indicated level on either the primary orbackup instrument channel of greater than 0 feet above top of fuel storage rack.The primary and backup instrument channel sensing components are monitoring the fuel storage area. The design is not complete at this time, but TVA plans toscale instrument channels from full pool to top of fuel rack. The top of active fuelis 18.1 inches below the top of the fuel rack. An instrument channel accuracycalculation, which includes all instrument channel components, is not complete atthis time. However, TVA anticipates the instrument channel uncertainty to beless than 12 inches. This monitoring level assures that there is adequate waterlevel above the stored fuel seated in the rack.E1-1 of 15 RAI-1Please provide the following:
a) The specific elevations within the SFP as Levels 1, 2 and 3. For Level 1, specify how theidentified location represents the HIGHER of the two points described in theNEI 12-02 guidance for this level.b) A clearly labeled sketch depicting the elevation view of the proposed typical mountingarrangement for the portions of instrument channel consisting of permanent measurement channel equipment (e.g., fixed level sensors and/or stilling wells, andmounting brackets).
Indicate on this sketch the datum values representing Level 1,Level 2, and Level 3 as well as the top of the fuel. Indicate on this sketch the portion ofthe level sensor measurement range that is sensitive to measurement of the fuel poollevel, with respect to the Level 1, Level 2, and Level 3 datum points.TVA Responsea) The specific elevations corresponding to the three levels are indicated on the sketch onpage E1-3. TVA will use the normal spent fuel pool water level at WBN (749.125 feet) asLevel 1. The normal spent fuel pool water level is higher than the coolant inlet pipe thatis at elevation 745.125 feet. This complies with NEI 12-02 requirements as outlinedbelow:Level at which reliable suction loss occurs due to uncovering of the coolant inletpipe.The WBN SFP coolant pipe is at elevation 745.125 feet.* The level at which the water height, assuming saturated conditions above thecenterline of the cooling pump suction provides the required net positive suctionhead (NPSH) specified by the pump manufacturer or engineering analysis.
WBN "Spent Fuel Pool Cooling System Flow and Temperature Calculations During Flood Mode and Normal Mode" has determined that adequate NPSH forSFP cooling pumps exists for temperatures up to 190 degrees Fahrenheit (F).However, this analysis does not ensure NPSH protection for temperatures thatexceed 190 degrees F. TVA has entered the requirement to provide operational guidance for NPSH protection during saturated conditions in the Corrective ActionProgram.
WBN will evaluate procedure changes and calculation changes tosupport operation during a beyond design basis saturated condition above 190degrees F. TVA will provide an update to the resolution by October 31, 2013.b) The Guided Wave Radar system can only sense level changes above the weight andthere is a small distance above the weight that the manufacturer defines as the deadzone. Preliminary discussions with the manufacturer have indicated that the totaldistance above the SFP rack where level changes cannot be detected is less than onefoot. The exact distance has not been specified at this point. A sketch for Spent FuelPool Level is shown on page E1 -3 which shows the locations of Levels 1, 2 and 3; theinstrument full span range and top of fuel rack. The space shown below Level 3 andE1-2 of 15 above "Top of Fuel Rack" is the area where level changes would not be detected.
TVAwill utilize the Top of the dead zone as Level 3 instead of Top of Fuel Storage Rack.POOL LEVELS AND REFERENCES Mounting ELEVATION REFERENCE Bracket OPERATING FLOOR LEVEL-757.0 47W200-3749.21' High water level Ref 47W855-1 R32100% LevelNORMAL WATER LEVEL ' --.749.125' Normal Water Level Ref 47W855-1Calculation EPM-JP-070192 WBN-78-D053 MEB-WBN-78 pg 23a745.125' SFP suction strainer 47W454-3-.... 734.29' NEI 12-02 section 2.3.2(Top of Rack + 10 Feet)725.29' Max of1 foot above Rack....- 724.29'Top of ActiveFuel 722.78'L36 130208 801.--709.23'Weight and Dead Zone aboveweight shown.Top of dead zone is 0% LevelDrawing DCA 38623-01-6 47W855-1E1-3 of 15 3.0 INSTRUMENTATION DESIGN FEATURES3.2 Arrangement The OIP states, in part, thatPrimary (fixed) instrument channel:
The primary instrument channel level sensorwill be located in northwest corner of the SFP (close to Unit 1). The electronics for signal conditioning will be located inside the Unit 1 upper containment accessroom. The primary instrument channel will provide continuous level indication from maximum operating level (26.6 feet above top of active fuel or 25.1 feetabove top of fuel storage racks) to the top of the fuel storage racks (zero feet).The continuous indication will be provided by a Guided Wave Radar transmitter utilizing a remote sensor mounted above the SFP with a flexible cable extending down to the top of the fuel storage racks. TVA defines the top of the fuel storagerack to be the level within one foot above the rack.Backup instrument channel:
The backup instrument channel level sensor will belocated in northeast corner of the SFP (close to Unit 2). The electronics for signalconditioning will be located inside the Unit 2 upper containment access room.The backup instrument channel will provide continuous level indication frommaximum operating level (26.6 feet above top of active fuel or 25.1 feet above topof fuel storage racks) to the top of the fuel storage racks (zero feet). Thecontinuous indication will be provided by a Guided Wave Radar transmitter utilizing a remote sensor mounted above the SFP with a flexible cable extending down to top of fuel storage racks. TVA defines the top of the fuel storage rack tobe the level within one foot above the rack.RAI-2Please provide a clearly labeled sketch or marked-up plant drawing of the plan view of the SFParea, depicting the SFP inside dimensions, the planned locations/placement of the primary andback-up SFP level sensors, and the proposed routing of the cables that will extend from thesensors toward the location of the local electronics cabinets and read-out/display devices in themain control room or alternate accessible location.
TVA ResponseEngineering for the SFP Instrumentation Level channels has completed 10% design review.Design Change Notice (DCN) 59683 has been assigned for WBN Units 1 and 2 and is scheduled to be issued September 27, 2013. Details on actual mounting locations will be available aftervendor mounting bracket design has been completed.
TVA will provide these details byOctober 31, 2013.E1-4 of 15 3.3 MountingThe OIP states, in part, thatLevel sensors will be mounted above the SFP, and qualified by analysis to thesame requirements as Safety Related, Seismic Category I, as defined in the WBNseismic design basis. The remaining channel components and cable routing shallbe mounted in accordance with the WBN Seismic Category 1 designrequirements.
RAI-3Please provide the following:
a) The design criteria that will be used to estimate the total loading on the mountingdevice(s),
including static weight loads and dynamic loads. Describe the methodology that will be used to estimate the total loading, inclusive of design basis maximum seismicloads and the hydrodynamic loads that could result from pool sloshing or other effectsthat could accompany such seismic forces.b) A description of the manner in which the level sensor (and stilling well, if appropriate) willbe attached to the refueling floor and/or other support structures for each planned point ofattachment of the probe assembly.
Indicate in a schematic the portions of the levelsensor that will serve as points of attachment for mechanical/mounting or electrical connections.
c) A description of the manner by which the mechanical connections will attach the levelinstrument to permanent SFP structures so as to support the level sensor assembly.
TVA ResponseEngineering for the Spent Fuel Pool Instrumentation (SFPI) Level channels has completed 10%design review. Design criteria for compliance with the SFPI Order requirements have not beenfinalized at this time. Design Criteria and mounting details will be available after mountingbracket design and associated calculations have been completed.
TVA will provide these detailsby October 31, 2013.E1-5 of 15
3.4 Qualification
The OIP states, in part, thatInstrument channel reliability shall be established by use of an augmented qualityassurance process.
Qualification of equipment mounted in the proximity of the SFPwill be evaluated to survive operation in the temperature,
- humidity, seismic,shock/vibration, boron, and radiation levels anticipated for SFP operation, including the conditions encountered with SFP inventory at reduced levels for a minimum ofseven (7) days post event. The NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide" (References 5 and 7), defines requirements foravailability of FLEX equipment.
FLEX equipment necessary to mitigate the event willbe available on site to ensure deployment can be accomplished in a timely manner.RAI-4Please provide the following:
a) A description of the specific method or combination of methods you intend to apply todemonstrate the reliability of the permanently installed equipment underbeyond-design-basis (BDB) ambient temperature,
- humidity, shock, vibration, andradiation conditions.
b) A description of the testing and/or analyses that will be conducted to provide assurance that the equipment will perform reliably under the worst-case credible design basisloading at the location where the equipment will be mounted.
Include a discussion of thisseismic reliability demonstration as it applies to a) the level sensor mounted in the SFParea, and b) any control boxes, electronics, or read-out and re-transmitting devices thatwill be employed to convey the level information from the level sensor to the plantoperators or emergency responders.
c) A description of the specific method or combination of methods that will be used toconfirm the reliability of the permanently installed equipment such that following a seismicevent the instrument will maintain its required accuracy.
TVA ResponseEngineering for the SFPI Level channels has completed 10% design review. Details onqualification, including methodology and analysis to determine reliability, will be available aftervendor testing and design have been completed.
TVA will provide these details byOctober 31, 2013.E1-6 of 15
3.5 Independence
The OIP states, in part, thatElectrical independence of the primary and backup channels of the permanently installed instrumentation is obtained by separating the channels.
The primary channel sensor willbe mounted in the northwest comer of the SFP and the backup channel sensor will bemounted in the northeast corner. The channels will be powered from batteries maintained in a charged state by station Vital 120 Volt Alternating Current (Vac) which isderived from Safety Related Vital Batteries.
Each channel will be maintained in acharged condition from different Vital Alternating Currents (AC) buses.RAI-5Please provide the following:
a) A description of how the two channels of the proposed level measurement system ineach pool meet this requirement so that the potential for a common cause event toadversely affect both channels is minimized to the extent practicable.
b) Further information describing the design and installation of each level measurement system, consisting of level sensor electronics,
- cabling, and readout devices.
Pleaseaddress how independence of these components of the primary and back-up channels isachieved through the application of independent power sources, physical and spatialseparation, independence of signals sent to the location(s) of the readout devices, andthe independence of the displays.
TVA Responsea) The primary and backup sensors will be mounted as close as practical to different corners of the spent fuel pool to take advantage of natural protection provided by spatialseparation.
Conduit or other means of cable protection such as routing the cable insidethe wall of the pool will be utilized in the area of SFP. Conduit and cabling in the SFParea will also be routed to take advantage of natural protection provided by spatialseparation.
b) The channels of SFP Level instruments will be powered from independent batteries maintained in a charged state by station Vital 120 Volt Alternating Current (Vac). Inaddition, station Vital 120 Vac is derived from Safety Related Vital Batteries.
Eachchannel will be maintained in a charged condition from independent Vital 120 Vacsources.
The power cable to each independent SFP level channel battery will be routedand separated in accordance with site design standards for redundant channels/trains ofsafety related instrumentation.
Conduit and cabling outside the SFP area for both channels will be routed and separated in accordance with site design standards for redundant channels/trains of safety relatedinstrumentation.
This conduit and cable separation and routing criteria will be utilized forall channel components including transmitter, battery enclosure, and main control room(MCR) indicator for the channel providing MCR indication.
E1-7 of 15 3.6 Power SuppliesThe OIP states, in part, thatThe power supplies for the instrument channels are arranged as follows:* The primary instrument channel components will be powered bybatteries maintained in a charged state by station Vital 120 Vac whichis derived from Safety Related Vital Batteries.
Primary instrument channel battery sizing is in progress, but is anticipated to providecontinuous indication for a period of at least 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. The SFPinstrument battery charger will have power available any time the VitalBatteries and Vital Inverters power source is available.
Vital Batteries and Vital Inverters are anticipated to be continuously available becauseFLEX Diesel Generators (D/Gs) are being added as part ofOrderEA-12-049 and will provide power to the Vital Battery Chargers.
See Reference 9 Chapter 8 for a detailed description of the existingVital AC power distribution.
- The backup instrument channel components will be powered bybatteries maintained in a charged state by station Vital 120 Vac which isderived from Safety Related Vital Batteries.
A different station Vital120 Vac power source will be utilized than that chosen for the primaryinstrument channel Secondary instrument channel battery sizing is inprogress, but is anticipated to provide continuous indication for a periodof at least 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. SFP instrument battery charger will have poweravailable any time the vital batteries and Vital Inverters power source isavailable.
Vital Batteries and Vital Inverters are anticipated to becontinuously available because FLEX DIGs are being added as part ofOrder EA-12-049 and will provide power to the Vital Battery Chargers.
See Reference 9 Chapter 8 for a detailed description of the existingVital AC power distribution.
- Both the primary and backup channels will be designed to allow analternate AC source to be readily connected.
The alternate AC sourcewill be from the FLEX 225 kilo Volt- Ampere (kVA) DIG through a stepdown transformer.
The FLEX 225 kVA DIG and associated connections will be stored in accordance with reasonable protection guidance ofNEI 12-06 as defined by NEI 12-02.RAI-6a) A description of the electrical AC power sources and capacities for the primary andbackup channels.
b) If the level measurement channels are to be powered through a battery system(either directly or through an Uninterruptible Power Supply (UPS)), please provide thedesign criteria that will be applied to size the battery in a manner that ensures, withmargin, that the channel will be available to run reliably and continuously following theonset of the BDB event for the minimum duration needed, consistent with the plantmitigation strategies for BDB external events (Order EA-12-049).
E1-8 of 15 TVA Responsea) A detailed description of Vital AC power system and its capacities has been providedin Chapter 8 of WBN Final Safety Analysis Report (FSAR) (Reference 9 in Februarysubmittal).
NEI 12-06 section 3.2.1.3 initial condition 8 states "Installed electrical distribution system, including inverters and battery chargers, remain available provided they are protected consistent with current station design."
The WBNinstalled electrical distribution system, including inverters and battery chargers arefully protected and seismically mounted inside a safety related structure and aboveflood elevation.
b) The design criteria for compliance with the SFPI Order requirements have not beenfinalized at this time, however, it is anticipated that calculations will address DesignMargin, Aging Margin and Temperature Correction Factors.
TVA assumes a batterylife of 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> which provides margin to the preliminary analysis of a 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> batterylife. TVA revised the anticipated battery life to 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> to provide margin to addressissues identified during the design process.
FLEX Coping strategies will restorepower to the battery charger or provide an alternate AC source well in advance of84 hours. This change is noted in the WBN first 6-month update to the SFP OIPsubmitted August 28, 2013.E1-9 of 15 3.7 AccuracyThe OIP states, in part, that:The accuracy will be consistent with the guidelines of NRC JLD-ISG-2012-03 andNEI 12-02. The instrument channel will be scaled from full pool to the top of the fuel rack.Top of active fuel is 18.1 inches below the top of the rack. The instrument channelaccuracy calculation, which includes all of the instrument channel components, is notcomplete at this time; however, TVA anticipates the instrument channel uncertainty to beless than 12 inches [01-1].RAI-7Provide the following:
a) An estimate of the expected instrument channel accuracy performance (e.g., inpercentage of span) under both a) normal spent fuel pool level conditions (approximately Level I or higher) and b) at the beyond-design-basis conditions (i.e., radiation, temperature,
- humidity, post-seismic and post-shock conditions) that wouldbe present if the SFP level were at the Level 2 and Level 3 datum points.b) A description of the methodology that will be used for determining the maximum alloweddeviation from the instrument channel design accuracy that will be employed undernormal operating conditions as an acceptance criterion for a calibration procedure to flagto operators and to technicians that the channel requires adjustment to within the normalcondition design accuracy.
TVA ResponseEngineering for the SFPI Level channels has completed 10% design review. Details onaccuracy and allowed deviation will be available after vendor design and calculations have beencompleted.
TVA will provide these details by October 31, 2013.El-10 of 15 3.8 TestingThe OIP states, in part, thatThe instrument channel design will provide for routine testing and calibration consistent with the guidelines of NRC JLD-ISG-2012-03 and NEI 12-02.The full level indication of the SFP indicator will be compared to fixed marks within theSFP to validate that the transmitter zero adjustment has not drifted.
The sensormounting design will incorporate a bracket that provides a calibrated distance to raise thesensor to confirm that the instrument system is performing within the channel accuracycalculation.
Existing work control processes such as Calibration Surveillance Instructions (Sis),Preventative Maintenance procedures and Work Orders will be utilized to perform testingand maintenance on the instrument channels.
The Sis or periodic instructions willvalidate the functionality of the installed instrument channels within 60 days of a plannedrefueling outage considering normal testing scheduling allowances (e.g., +1-25 percent),
provided that the instruction has not been performed within the past 12 months.Allowable channel out of service times and associated actions will be consistent with theguidance provided in NEI 12-02.RAI-7Please provide the following:
a) A description of the capability and provisions the proposed level sensing equipment willhave to enable periodic testing and calibration, including how this capability enables theequipment to be tested in-situ.b) A description of how such testing and calibration will enable the conduct of regularchannel checks of each independent channel against the other, and against any otherpermanently installed spent fuel pool level instrumentation.
c) A description of how calibration tests and functional checks will be performed and thefrequency at which they will be conducted.
Discuss how these surveillances will beincorporated into the plant surveillance program.d) A description of what preventative maintenance tasks are required to be performed during normal operation, and the planned maximum surveillance interval that isnecessary to ensure that the channels are fully conditioned to accurately and reliablyperform their functions when needed.TVA ResponseEngineering for the SFPI Level channels has completed 10% design review. Details ontestability features and preventive maintenance will be available after vendor design, calculations and procedures have been completed.
TVA will provide these details by October 31, 2013.El-11 of 15 3.9 DisplayThe OIP states, in part, thatThe displays will be consistent with the guidelines of NRC JLD-ISG-2012-03 andNEI 12-02. The detailed engineering design is not complete at this time. Oneinstrument channel display will be located in the Main Control Room. The otherinstrument channel display will be located in close proximity to the Backup ControlRoom. Both indicator locations are promptly accessible to plant operations staffand do not require personnel to enter the area surrounding the SFP.RAI-8Please provide the following:
a) Since one of the display locations is not in the main control room, provide a description ofthe display location that addresses primary and alternate access route evaluation, continuous habitability at display location(s),
continual resource availability for personnel responsible to promptly read displays, and provisions for verbal communications withdecision makers for the various SFP drain down scenarios and external events.b) The reasons justifying why the location selected will enable the information from theseinstruments to be considered "promptly accessible".
Include consideration of variousdrain-down scenarios.
TVA Responsea) WBN SFP is shared between both units and will have a total of two level instrument channels.
One instrument channel display will be located in the Main Control Room.Engineering for the SFPI Level channels is in progress;
- however, the exact location forthe battery pack/display enclosure for both channels has not yet been determined.
Thesecond instrument channel display is anticipated to be located in the Electric BoardRoom which is in close proximity to the Auxiliary Control Room. The Electric BoardRoom is a mild environment, is promptly accessible (2 minute walk) by main control roompersonnel and is not subject to the environmental conditions associated with boiling in theSFP. Communications by radio or telephone is available if needed. The route to theElectric Board Room/Auxiliary Control Room area from the Main Control Room will be thesame route that is utilized during design basis events because the route is within a safetyrelated, seismic structure.
The pathway is expected to remain intact following a seismicevent. See the sketch below for the route from the Main Control Room to the ElectricBoard Room.b) The Electric Board Room is in a mild environment, is promptly accessible (2 minute walk)by main control room personnel.
Therefore, the environment is not affected by theenvironmental conditions associated with any drain down scenario.
E1-12 of 15 Route from Main Control Room to Electric Board RoomEl-13 of 15 4.0 PROGRAM FEA TURES4.2 Procedures The OIP states, in part, thatProcedures will be developed using guidelines and vendor instructions toaddress the maintenance and operation issues associated with the new SFPinstrumentation.
Procedures will address a strategy for ensuring SFP water leveladdition is initiated at an appropriate time consistent with implementation of NEI12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide"(References 5 and 7).RAI-1OPlease provide the following:
a) A list of the operating (both normal and abnormal response) procedures, calibration/test procedures, maintenance procedures, and inspection procedures that will be developed for use of the SFP instrumentation in a manner that addresses the order requirements.
b) A brief description of the specific technical objectives to be achieved within eachprocedure.
If your plan incorporates the use of portable spent fuel level monitoring components, please include a description of the objectives to be achieved with regard tothe storage location and provisions for installation of the portable components whenneeded.TVA ResponseEngineering for the SFPI Level channels has completed 10% design review. Maintenance requirements for Beyond-Design-Basis equipment are under development at this time by EPRI.Inspection, maintenance, repair, operation, abnormal response and administrative controlguidelines will be available after industry guidelines have been completed.
TVA will providethese details by October 31, 2013.E1-14 of 15
'4.3 Testing and Calibration The 0IP states, in part, thatThe instrument channel design will provide for routine testing and calibration consistent with the guidelines of NRC JLD-ISG-2012-03 and NEI 12-02.The full level indication of the SFP indicator will be compared to fixed marks withinthe SFP to validate that the transmitter zero adjustment has not drifted.
Thesensor mounting design will incorporate a bracket that provides a calibrated distance to raise the sensor to confirm that the instrument system is performing within the channel accuracy calculation.
Existing work control processes such as Calibration Surveillance Instructions (Sis), Preventative Maintenance procedures and Work Orders will be utilized toperform testing and maintenance on the instrument channels.
The Sis or periodicinstructions will validate the functionality of the installed instrument channelswithin 60 days of a planned refueling outage considering normal testingscheduling allowances (e.g., +1-25 percent),
provided that the instruction has notbeen performed within the past 12 months. Allowable channel out of servicetimes and associated actions will be consistent with the guidance provided inNEI 12-02.RAI-11Please provide the following:
a) Further information describing the maintenance and testing program the licensee willestablish and implement to ensure that regular testing and calibration is performed andverified by inspection and audit to demonstrate conformance with design and systemreadiness requirements.
Include a description of your plans for ensuring that necessary channel checks, functional tests, periodic calibration, and maintenance will be conducted for the level measurement system and its supporting equipment.
b) A description of how the guidance in NEI 12-02 Section 4.3 regarding compensatory actions for one or both non-functioning channels will be addressed.
c) A description of the compensatory actions to be taken in the event that one of theinstrument channels cannot be restored to functional status within 90 days.TVA ResponseEngineering for the SFPI Level channels has completed 10% design review. Routine testingguidelines, including channel checks, functional tests, and periodic calibration verification havenot been developed at this time. In addition, compensatory actions have not been finalized atthis time. TVA will provide these details by October 31, 2013.E1-15 of 15 ENCLOSURE 2TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT, UNITS I AND 2LIST OF COMMITMENTS ENCLOSURE2 LIST OF COMMITMENTS
- 1. TVA will provide a response to Request for Additional Information (RAI) questions 2 -4, 7, 8, 10, and 11 by October 31, 2013, after the design of the spent fuel poolinstrumentation has been completed.
TVA will also provide an update to RAIquestion 1.a in this response.
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