ML13254A065

Response to NRC Request for Additional Information Related to Overall Integrated Plan in Response to the Commission Order Modifying Licenses with Regard to Requirements for Reliable Spent Fuel Pool Instrumentation

ML13254A065
Person / Time
Site:	Watts Bar
Issue date:	09/06/2013
From:	James Shea 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 37402 September 6, 2013 10 CFR 2.202 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390 Watts Bar Nuclear Plant, Unit 2 Construction Permit No. CPPR-92 NRC Docket No. 50-391

Subject:

Response to NRC Request for Additional Information Related to Overall Integrated Plan in Response to the Commission Order Modifying Licenses with 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 with Regard to Reliable Spent Fuel Instrumentation,"

dated March 12, 2012

2. TVA Letter, "Tennessee Valley Authority (TVA) - Overall Integrated plan in response to the March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051) for Watts Bar Nuclear Plant," dated February 28, 2013

3. NRC Letter, "Watts Bar Nuclear Plant, Units 1 and 2 - Request for Additional Information Regarding Overall Integrated Plan in Response to the Commission Order Modifying Licenses with Regard to Requirements for Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051)

(TAC Nos. MF0951 and MF1 178)," dated August 2, 2013 The purpose of this letter is to provide the Tennessee Valley Authority's (TVA) response to the Request for Additional Information (RAI) regarding the Watts Bar Nuclear Plant's (WBN) Overall Integrated Plan submitted to Nuclear Regulatory Commission (NRC) pursuant to Order EA-12-051, "Order Modifying Licenses with Regard to Reliable Spent Fuel Pool Instrumentation."

Printedon recycled paper

U.S. Nuclear Regulatory Commission Page 2 September 6, 2013 On 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 provide for 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 in of the Order would be achieved, by February 28, 2013 (Reference 1). TVA submitted the OIP for WBN, Units land 2 on February 28, 2013 (Reference 2). On August 2, 2013, the NRC issued an RAI regarding the OIP submitted by TVA for WBN, Units 1 and 2 (Reference 3). The RAI requested a response be provided within 30 days of the date of the 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 to September 6, 2013, was requested and approved. of this letter provides TVA's responses to the RAI submitted in Reference 3. As noted in response to RAI questions 2 - 4, 7, 8, 10, and 11, the requested information is not currently available, but will be provided by October 31, 2013, after the spent fuel pool instrumentation design has been completed. Enclosure 2 provides a new commitment to provide 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 on the 6th day of September 2013.

Resp ully, J. .Stea Vi,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 to Requirements for Reliable Spent Fuel Pool Instrumentation

2. List of Commitments cc (Enclosures):

NRC Regional Administrator - Region II NRR Director - NRC Headquarters NRR Project Manager - Watts Bar Nuclear Plant, Unit 1 NRR Project Manager - Watts Bar Nuclear Plant, Unit 2 NRC Senior Resident Inspector - Watts Bar Nuclear Plant, Unit 1

ENCLOSURE I TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT, UNITS I AND 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION RELATED TO OVERALL INTEGRATED PLAN IN RESPONSE TO THE COMMISSION ORDER MODIFYING LICENSES WITH REGARD TO REQUIREMENTS FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION

ENCLOSUREI

1.0 INTRODUCTION

By letter dated February28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13063A440), Tennessee Valley Authority (TVA) submitted an Overall Integrated Plan (OIP) in response to the March 12, 2012, U.S. Nuclear Regulatory Commission (NRC) Ordermodifying licenses with regardto requirements for Reliable Spent Fuel Pool (SFP)Instrumentation(OrderNumber EA-12-051; ADAMS Accession No. ML12054A679) for Watts Bar NuclearPlant, Units 1 & 2. The NRC staff endorsed Nuclear Energy Institute (NEI) 12-02 "IndustryGuidance for Compliance with U.S. Nuclear Regulatory Commission (NRC)

OrderEA-12-051, to Modify Licenses with Regard to Reliable Spent Fuel Pool Instrumentation,"

Revision 1, dated August 2012 (ADAMS Accession No. ML12240A307), with exceptions as documented in Interim Staff Guidance 2012-03, "Compliancewith Order EA-12-051, Reliable SFP Instrumentation,"Revision 0, dated August 29, 2012 (ADAMS Accession No. ML12221A339).

The NRC staff has reviewed TVA's February28, 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,that Key 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 of greater than 26.3 feet above the top of active fuel seated in the storage racks based on a calculation demonstrating a water level that ensurespump net positive suction head (NPSH) is adequate for normal fuel pool cooling system operation.

• Level adequate to provide substantialradiation shielding for a person standing on the SFP operating deck - Indicated level on either the primary or backup instrument channel of greater than 10 feet (+/- 1 foot) above the top of stored fuel seated in the storage racks based on NEI 12-02 Section 2.3.2, bullet 1. This monitoring level ensures there is an adequate water level to provide substantial radiation shielding for a person standing on the SFP operating deck.

0 Level where fuel remains covered - Indicated level on either the primary or backup 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 to scale instrumentchannels from full pool to top of fuel rack. The top of active fuel is 18.1 inches below the top of the fuel rack. An instrument channel accuracy calculation, which includes all instrument channel components, is not complete at this time. However, TVA anticipates the instrument channel uncertainty to be less than 12 inches. This monitoring level assures that there is adequate water level above the stored fuel seated in the rack.

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RAI-1

Please provide the following:

a) The specific elevations within the SFP as Levels 1, 2 and 3. ForLevel 1, specify how the identified location represents the HIGHER of the two points described in the NEI 12-02 guidance for this level.

b) A clearly labeled sketch depicting the elevation view of the proposed typical mounting arrangementfor the portions of instrument channel consisting of permanent measurement channel equipment (e.g., fixed level sensors and/orstilling wells, and mounting brackets). Indicate on this sketch the datum values representingLevel 1, Level 2, and Level 3 as well as the top of the fuel. Indicate on this sketch the portion of the level sensormeasurement range that is sensitive to measurement of the fuel pool level, with respect to the Level 1, Level 2, and Level 3 datum points.

TVA Response a) The specific elevations corresponding to the three levels are indicated on the sketch on page E1-3. TVA will use the normal spent fuel pool water level at WBN (749.125 feet) as Level 1. The normal spent fuel pool water level is higher than the coolant inlet pipe that is at elevation 745.125 feet. This complies with NEI 12-02 requirements as outlined below:

Level at which reliable suction loss occurs due to uncovering of the coolant inlet pipe.

The WBN SFP coolant pipe is at elevation 745.125 feet.

• The level at which the water height, assuming saturatedconditions above the centerline of the cooling pump suction provides the required net positive suction head (NPSH) specified by the pump manufactureror engineering analysis.

WBN "Spent Fuel Pool Cooling System Flow and Temperature Calculations During Flood Mode and Normal Mode" has determined that adequate NPSH for SFP cooling pumps exists for temperatures up to 190 degrees Fahrenheit (F).

However, this analysis does not ensure NPSH protection for temperatures that exceed 190 degrees F. TVA has entered the requirement to provide operational guidance for NPSH protection during saturated conditions in the Corrective Action Program. WBN will evaluate procedure changes and calculation changes to support operation during a beyond design basis saturated condition above 190 degrees 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 and there is a small distance above the weight that the manufacturer defines as the dead zone. Preliminary discussions with the manufacturer have indicated that the total distance above the SFP rack where level changes cannot be detected is less than one foot. The exact distance has not been specified at this point. A sketch for Spent Fuel Pool Level is shown on page E1 -3 which shows the locations of Levels 1, 2 and 3; the instrument full span range and top of fuel rack. The space shown below Level 3 and E1-2 of 15

above "Top of Fuel Rack" is the area where level changes would not be detected. TVA will 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 47W200-3

-757.0 749.21' High water level Ref 47W855-1 R32 100% Level NORMAL WATER LEVEL . ' - - 749.125' Normal Water Level Ref 47W855-1 Calculation EPM-JP-070192 WBN-78-D053 MEB-WBN-78 pg 23a 745.125' SFP suction strainer 47W454-3

-.... 734.29' NEI 12-02 section 2.3.2 (Top of Rack + 10 Feet) 725.29' Max of Weight and Dead Zone above 1foot above Rack weight shown.

Top of dead zone is 0% Level

....- 724.29' Drawing DCA 38623-01-6 Top of Active Fuel 722.78' L36 130208 801

.- - 709.23' 47W855-1 E1-3 of 15

3.0 INSTRUMENTATION DESIGN FEATURES 3.2 Arrangement The OIP states, in part,that Primary (fixed) instrument channel: The primary instrument channel level sensor will be located in northwest cornerof the SFP (close to Unit 1). The electronics for signal conditioningwill be located inside the Unit 1 upper containment access room. The primary instrument channel will provide continuous level indication from maximum operating level (26.6 feet above top of active fuel or 25.1 feet above top of fuel storage racks) to the top of the fuel storage racks (zero feet).

The continuous indicationwill 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 storage rack to be the level within one foot above the rack.

Backup instrument channel: The backup instrument channel level sensorwill be located in northeast cornerof the SFP (close to Unit 2). The electronics for signal conditioningwill be located inside the Unit 2 upper containment access room.

The backup instrument channel will provide continuous level indication from maximum operatinglevel (26.6 feet above top of active fuel or 25.1 feet above 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 top of fuel storage racks. TVA defines the top of the fuel storage rack to be the level within one foot above the rack.

RAI-2

Please provide a clearly labeled sketch or marked-up plant drawing of the plan view of the SFP area, depicting the SFP inside dimensions, the planned locations/placementof the primary and back-up SFP level sensors, and the proposed routing of the cables that will extend from the sensors toward the location of the local electronics cabinets and read-out/displaydevices in the main control room or alternate accessible location.

TVA Response Engineering 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 after vendor mounting bracket design has been completed. TVA will provide these details by October 31, 2013.

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3.3 Mounting The OIP states, in part, that Level sensors will be mounted above the SFP, and qualified by analysis to the same requirements as Safety Related, Seismic Category I, as defined in the WBN seismic design basis. The remaining channel components and cable routing shall be mounted in accordancewith the WBN Seismic Category 1 design requirements.

RAI-3

Please provide the following:

a) The design criteria that will be used to estimate the total loading on the mounting device(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 seismic loads and the hydrodynamic loads that could result from pool sloshing or other effects that could accompany such seismic forces.

b) A description of the manner in which the level sensor (and stilling well, if appropriate)will be attached to the refueling floor and/or other support structuresfor each planned point of attachment of the probe assembly. Indicate in a schematic the portions of the level sensor that will serve as points of attachment for mechanical/mountingor electrical connections.

c) A description of the manner by which the mechanicalconnections will attach the level instrument to permanent SFP structuresso as to support the level sensor assembly.

TVA Response Engineering 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 been finalized at this time. Design Criteria and mounting details will be available after mounting bracket design and associated calculations have been completed. TVA will provide these details by October 31, 2013.

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3.4 Qualification The OIP states, in part,that Instrument channel reliability shall be established by use of an augmented quality assuranceprocess. Qualificationof equipment mounted in the proximity of the SFP will be evaluated to survive operation in the temperature,humidity, seismic, shock/vibration, boron, and radiationlevels anticipatedfor SFP operation, including the conditions encountered with SFP inventory at reduced levels for a minimum of seven (7) days post event. The NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide" (References 5 and 7), defines requirements for availabilityof FLEX equipment. FLEX equipment necessary to mitigate the event will be available on site to ensure deployment can be accomplished in a timely manner.

RAI-4

Please provide the following:

a) A description of the specific method or combination of methods you intend to apply to demonstrate the reliabilityof the permanently installed equipment under beyond-design-basis(BDB) ambient temperature,humidity, shock, vibration, and radiationconditions.

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 basis loading at the location where the equipment will be mounted. Include a discussion of this seismic reliabilitydemonstration as it applies to a) the level sensormounted in the SFP area, and b) any control boxes, electronics, or read-out and re-transmittingdevices that will be employed to convey the level information from the level sensor to the plant operatorsor emergency responders.

c) A description of the specific method or combination of methods that will be used to confirm the reliabilityof the permanently installedequipment such that following a seismic event the instrument will maintainits required accuracy.

TVA Response Engineering for the SFPI Level channels has completed 10% design review. Details on qualification, including methodology and analysis to determine reliability, will be available after vendor testing and design have been completed. TVA will provide these details by October 31, 2013.

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3.5 Independence The OIP states, in part, that Electricalindependence of the primary and backup channels of the permanently installed instrumentationis obtained by separatingthe channels. The primary channel sensor will be mounted in the northwest comer of the SFP and the backup channel sensorwill be mounted in the northeast corner. The channels will be powered from batteries maintainedin a charged state by station Vital 120 Volt Alternating Current(Vac) which is derived from Safety Related Vital Batteries. Each channel will be maintainedin a charged condition from different Vital Alternating Currents (AC) buses.

RAI-5

Pleaseprovide the following:

a) A description of how the two channels of the proposedlevel measurement system in each pool meet this requirement so that the potential for a common cause event to adversely affect both channels is minimized to the extent practicable.

b) Furtherinformation describing the design and installationof each level measurement system, consisting of level sensor electronics, cabling, and readout devices. Please address how independence of these components of the primary and back-up channels is achieved through the application of independentpower sources, physical and spatial separation,independence of signals sent to the location(s) of the readout devices, and the independence of the displays.

TVA Response a) 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 spatial separation. Conduit or other means of cable protection such as routing the cable inside the wall of the pool will be utilized in the area of SFP. Conduit and cabling in the SFP area will also be routed to take advantage of natural protection provided by spatial separation.

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). In addition, station Vital 120 Vac is derived from Safety Related Vital Batteries. Each channel will be maintained in a charged condition from independent Vital 120 Vac sources. The power cable to each independent SFP level channel battery will be routed and separated in accordance with site design standards for redundant channels/trains of safety 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 related instrumentation. This conduit and cable separation and routing criteria will be utilized for all channel components including transmitter, battery enclosure, and main control room (MCR) indicator for the channel providing MCR indication.

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3.6 Power Supplies The OIP states, in part, that The power supplies for the instrument channels are arranged as follows:

• The primary instrument channel components will be powered by batteries maintained in a charged state by station Vital 120 Vac which is derived from Safety Related Vital Batteries. Primary instrument channel battery sizing is in progress, but is anticipated to provide continuous 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 SFP instrument battery charger will have power available any time the Vital Batteries and Vital Inverters power source is available. Vital Batteries and Vital Inverters are anticipated to be continuously available because FLEX Diesel Generators (D/Gs) are being added as part of OrderEA-12-049 and will provide power to the Vital Battery Chargers.

See Reference 9 Chapter 8 for a detailed description of the existing Vital AC power distribution.

• The backup instrument channel components will be powered by batteries maintained in a charged state by station Vital 120 Vac which is derived from Safety Related Vital Batteries. A different station Vital 120 Vac power source will be utilized than that chosen for the primary instrument channel Secondary instrument channel battery sizing is in progress, but is anticipated to provide continuous 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 />. SFP instrument battery charger will have power available any time the vital batteriesand Vital Inverters power source is available. Vital Batteries and Vital Inverters are anticipated to be continuously available because FLEX DIGs are being added as part of Order EA-12-049 and will provide power to the Vital Battery Chargers.

See Reference 9 Chapter 8 for a detailed description of the existing Vital AC power distribution.

• Both the primary and backup channels will be designed to allow an alternate AC source to be readily connected. The alternate AC source will be from the FLEX 225 kilo Volt- Ampere (kVA) DIG through a step down transformer. The FLEX 225 kVA DIG and associatedconnections will be stored in accordance with reasonable protection guidance of NEI 12-06 as defined by NEI 12-02.

RAI-6

a) A description of the electricalAC power sources and capacitiesfor the primary and backup channels.

b) If the level measurement channels are to be powered through a battery system (eitherdirectly or through an UninterruptiblePower Supply (UPS)), please provide the design criteria that will be applied to size the battery in a manner that ensures, with margin, that the channel will be available to run reliably and continuously following the onset of the BDB event for the minimum duration needed, consistent with the plant mitigation strategiesfor BDB external events (OrderEA-12-049).

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TVA Response a) A detailed description of Vital AC power system and its capacities has been provided in Chapter 8 of WBN Final Safety Analysis Report (FSAR) (Reference 9 in February submittal). 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 WBN installed electrical distribution system, including inverters and battery chargers are fully protected and seismically mounted inside a safety related structure and above flood elevation.

b) The design criteria for compliance with the SFPI Order requirements have not been finalized at this time, however, it is anticipated that calculations will address Design Margin, Aging Margin and Temperature Correction Factors. TVA assumes a battery life 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 /> battery life. 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 address issues identified during the design process. FLEX Coping strategies will restore power to the battery charger or provide an alternate AC source well in advance of 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br />. This change is noted in the WBN first 6-month update to the SFP OIP submitted August 28, 2013.

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3.7 Accuracy The OIP states, in part, that:

The accuracy will be consistent with the guidelines of NRC JLD-ISG-2012-03 and NEI 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 channel accuracycalculation, which includes all of the instrument channel components, is not complete at this time; however, TVA anticipatesthe instrument channel uncertainty to be less than 12 inches [01-1].

RAI-7

Provide the following:

a) An estimate of the expected instrument channel accuracyperformance (e.g., in percentage of span) under both a) normal spent fuel pool level conditions (approximatelyLevel I or higher)and b) at the beyond-design-basis conditions (i.e., radiation,temperature,humidity, post-seismic and post-shock conditions) that would be 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 allowed deviation from the instrument channel design accuracythat will be employed under normal operatingconditions as an acceptance criterion for a calibrationprocedure to flag to operatorsand to techniciansthat the channel requires adjustment to within the normal condition design accuracy.

TVA Response Engineering for the SFPI Level channels has completed 10% design review. Details on accuracy and allowed deviation will be available after vendor design and calculations have been completed. TVA will provide these details by October 31, 2013.

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3.8 Testing The OIP states, in part, that The instrument channel design will provide for routine testing and calibrationconsistent with the guidelines of NRC JLD-ISG-2012-03 and NEI 12-02.

The full level indication of the SFP indicatorwill be compared to fixed marks within the SFP to validate that the transmitterzero adjustment has not drifted. The sensor mounting design will incorporate a bracket that provides a calibrateddistance to raise the sensorto confirm that the instrument system is performing within the channel accuracy calculation.

Existing work control processes such as CalibrationSurveillance Instructions(Sis),

Preventative Maintenanceprocedures and Work Orders will be utilized to perform testing and maintenance on the instrument channels. The Sis or periodic instructions will validate the functionality of the installed instrument channels within 60 days of a planned refueling 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 associatedactions will be consistent with the guidance provided in NEI 12-02.

RAI-7

Please provide the following:

a) A description of the capability and provisions the proposed level sensing equipment will have to enable periodic testing and calibration,including how this capabilityenables the equipment to be tested in-situ.

b) A description of how such testing and calibrationwill enable the conduct of regular channel checks of each independent channel againstthe other, and against any other permanently installed spent fuel pool level instrumentation.

c) A description of how calibrationtests and functionalchecks will be performed and the frequency at which they will be conducted. Discuss how these surveillances will be incorporatedinto the plant surveillanceprogram.

d) A description of what preventative maintenance tasks are requiredto be performed during normal operation, and the planned maximum surveillance interval that is necessary to ensure that the channels are fully conditioned to accurately and reliably perform their functions when needed.

TVA Response Engineering for the SFPI Level channels has completed 10% design review. Details on testability 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.

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3.9 Display The OIP states, in part,that The displays will be consistent with the guidelines of NRC JLD-ISG-2012-03 and NEI 12-02. The detailed engineeringdesign is not complete at this time. One instrument channel display will be located in the Main Control Room. The other instrument channel display will be located in close proximity to the Backup Control Room. Both indicatorlocations are promptly accessible to plant operationsstaff and do not require personnel to enter the area surroundingthe SFP.

RAI-8

Please provide the following:

a) Since one of the display locations is not in the main control room, provide a description of the display location that addressesprimary and alternate access route evaluation, continuous habitabilityat display location(s), continual resource availabilityfor personnel responsible to promptly read displays, and provisions for verbal communications with decision makers for the various SFP drain down scenarios and external events.

b) The reasonsjustifying why the location selected will enable the information from these instrumentsto be considered "promptlyaccessible". Include considerationof various drain-down scenarios.

TVA Response a) 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 for the battery pack/display enclosure for both channels has not yet been determined. The second instrument channel display is anticipated to be located in the Electric Board Room which is in close proximity to the Auxiliary Control Room. The Electric Board Room is a mild environment, is promptly accessible (2 minute walk) by main control room personnel and is not subject to the environmental conditions associated with boiling in the SFP. Communications by radio or telephone is available if needed. The route to the Electric Board Room/Auxiliary Control Room area from the Main Control Room will be the same route that is utilized during design basis events because the route is within a safety related, seismic structure. The pathway is expected to remain intact following a seismic event. See the sketch below for the route from the Main Control Room to the Electric Board 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 the environmental conditions associated with any drain down scenario.

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Route from Main Control Room to Electric Board Room El-13 of 15

4.0 PROGRAM FEA TURES 4.2 Procedures The OIP states, in part, that Procedureswill be developed using guidelines and vendor instructions to address the maintenance and operation issues associatedwith the new SFP instrumentation. Procedureswill address a strategy for ensuring SFP water level addition is initiatedat an appropriatetime consistent with implementation of NEI 12-06, "Diverseand Flexible Coping Strategies (FLEX) Implementation Guide" (References 5 and 7).

RAI-1O Please provide the following:

a) A list of the operating (both normal and abnormalresponse)procedures, calibration/test procedures,maintenance procedures,and inspectionprocedures 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 each procedure. If your plan incorporatesthe use of portable spent fuel level monitoring components, please include a description of the objectives to be achieved with regard to the storage location and provisions for installationof the portable components when needed.

TVA Response Engineering 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 control guidelines will be available after industry guidelines have been completed. TVA will provide these details by October 31, 2013.

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'4.3 Testing and Calibration The 0IP states, in part, that The 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 indicatorwill be comparedto fixed marks within the SFP to validate that the transmitterzero adjustment has not drifted. The sensor 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 CalibrationSurveillance Instructions (Sis), Preventative Maintenance proceduresand Work Orders will be utilized to perform testing and maintenance on the instrument channels. The Sis or periodic instructionswill validate the functionality of the installedinstrument channels within 60 days of a planned refueling outage considering normal testing scheduling allowances (e.g., +1-25 percent), provided that the instructionhas not been performed within the past 12 months. Allowable channel out of service times and associatedactions will be consistent with the guidance provided in NEI 12-02.

RAI-11

Pleaseprovide the following:

a) Furtherinformation describingthe maintenance and testing program the licensee will establish and implement to ensure that regulartesting and calibrationis performed and verified by inspection and audit to demonstrate conformance with design and system readinessrequirements. 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 regardingcompensatory 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 the instrument channels cannot be restoredto functional status within 90 days.

TVA Response Engineering for the SFPI Level channels has completed 10% design review. Routine testing guidelines, including channel checks, functional tests, and periodic calibration verification have not been developed at this time. In addition, compensatory actions have not been finalized at this time. TVA will provide these details by October 31, 2013.

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ENCLOSURE 2 TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT, UNITS I AND 2 LIST 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 pool instrumentation has been completed. TVA will also provide an update to RAI question 1.a in this response.

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