ML13134A093

Request for Additional Information Regarding Overall Integrated Plan for Reliable Spent Fuel Pool Instrumentation

ML13134A093
Person / Time
Site:	Byron, Clinton, Quad Cities, LaSalle
Issue date:	06/07/2013
From:	Blake Purnell Division of Operating Reactor Licensing
To:	Pacilio M Exelon Generation Co
Blake Purnell, NRR/DORL 415-1380
References
TAC MF0791, TAC MF0872, TAC MF0873, TAC MF0979, TAC MF1052, TAC MF1053
Download: ML13134A093 (35)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 June 7, 2013 Mr. Michael J. Pacilio Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BYRON STATION, UNIT NOS. 1 AND 2; CLINTON POWER STATION, UNIT NO.1; LASALLE COUNTY STATION, UNITS 1 AND 2; AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING OVERALL INTEGRATED PLAN FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION (TAC NOS. MF0872, MF0873, MF0791, MF1119, MF1120, MF1052, AND MF1053)

Dear Mr. Pacilio:

By letters dated February 28, 2013, Exelon Generation Company (EGC), LLC submitted integrated plans for its operating reactors to the U.S. Nuclear Regulatory Commission (NRC) in response to the March 12, 2012, Commission Order modifying licenses with regard to requirements for reliable spent fuel pool instrumentation (Order EA-12-051).

The NRC staff is reviewing your submittals 1 for Byron Station, Unit Nos. 1 and 2; Clinton Power Station, Unit No.1; LaSalle County Station, Units 1 and 2; and Quad Cities Nuclear Power Station, Units 1 and 2, and has determined that additional information is required to complete the reviews. The specific information requested is addressed in the enclosures to this letter.

Please provide a response to this information request by July 5, 2013. If some information is unavailable by July 5, 2013, then provide the dates when additional information will be submitted.

If the NRC staff requires additional information regarding other EGC operating reactors, it will be requested by separate correspondence.

1 Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML13063A265, ML13059A306, ML13063A323, and ML13060A124.

M. Pacilio

-2 Should you have any questions, please feel free to contact me at 301-415-1380.

Blake Purnell, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-454, STN 50-455, 50-461,50-373,50-374,50-254, and 50-265

Enclosures:

1. RAI for Byron Station, Unit Nos. 1 and 2

2. RAI for Clinton Power Station, Unit No.1

3. RAI for LaSalle County Station, Units 1 and 2

4. RAI for Quad Cities Nuclear Power Station, Units 1 and 2 cc w/encls: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION OVERALL INTEGRATED PLAN IN RESPONSE TO COMMISSION ORDER MODIFYING LICENSE REQUIREMENTS FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION (ORDER EA-12-051)

EXELON GENERATION COMPANY, LLC BYRON STATION, UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-454 AND STN 50-455

1.0 INTRODUCTION

By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13063A265), Exelon Generation Company, LLC submitted an overall integrated plan (OIP) in response to the March 12, 2012, U.S. Nuclear Regulatory Commission (NRC) Order modifying licenses with regard to reliable spent fuel pool (SFP) instrumentation (Order EA-12-051; ADAMS Accession No. ML12054A679) for Byron Station, Unit Nos. 1 and 2. The NRC staff endorsed Nuclear Energy Institute, NEI 12-02, "Industry Guidance for Compliance with NRC Order EA-12-051, to Modify Licenses with Regard to Reliable SFP Instrumentation," Revision 1, dated AUgust 2012 (ADAMS Accession No. ML12240A307), with exceptions as documented in NRC Interim Staff Guidance, JLD-ISG 2012-03, "Compliance with Order EA-12-051, Reliable Spent Fuel Pool Instrumentation,"

Revision 0, dated August 29,2012 (ADAMS Accession No. ML12221A339).

The NRC staff has reviewed the February 28, 2013, response by the licensee and determined that 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 spent fuel pool water levels will be identified as follows:

Level adequate to support operation of the normal fuel pool cooling system (Level 1):

I ndicated level on either primary or backup instrument channel of greater than 19 feet (elevation 419'-2") above the top of the storage racks based on the design accuracy of

-2 the instrument channel (which is to be determined) and a resolution of 1 foot or better of both the primary and backup instrument channels. This is based on Spent Fuel Pool Cooling Pump suction strainer elevation. A calculation demonstrating adequate water level will be performed as part of the detailed engineering design phase to ensure the level is adequate for normal fuel pool cooling system operation Level adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck (Level 2): Indicated level on either the primary or backup instrument channel of greater than 10 feet (elevation [410'-2"D plus instrument channel accuracy above the top of the storage racks based on specification of this level as adequate in NRC..ILD-ISG-2012-03 and NEI 12-02, the specified design accuracy of thE~

instrument channel, and the relatively low sensitivity of dose rates to changes in water depth at this level. This monitoring level ensures there is an adequate water level to provide SUbstantial radiation shielding for a person standing on the SFP operating deck from direct gamma radiation from stored spent fuel.

Level where fuel remains covered (Level 3): Indicated level on either the primary or backup instrument channel of greater than 0 foot (elevation 400'-2") plus instrument channel accuracy above the top of the storage racks based upon the design accuracy (which is to be determined) of the instrument channel for both the primary and backup instrument channels. This monitoring level assures that water is covering the stored fuel seated in the rack.

RAI-1

Please provide the following:

(a) For Level 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 arrangement for the portions of instrument channel consisting of permanent measurement channel equipment (e.g., fixed level sensors and/or stilling wells, and mounting 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 of the level sensor measurement range that is sensitive to measurement of the fuel pool level, with respect to the Level 1, Level 2, and Level 3 datum points.

3.0 INSTRUMENTATION DESIGN FEATURES 3.2 Arrangement The OIP states, in part, that:

The current plan is to install SFP level sensors in the northwest and southwest corners of the SFP separated by a distance in excess of 20 feet. The sensors themselves will be mounted, to the extent practical, near the pool walls and below the pool curb to minimize their exposure to damaging debris and not interfere with SFP activities. Instrument channel electronics and power supplies will be located in seismic and missile protected

- 3 areas either below the SFP operating floor or in buildings other than the FHB [Fuel Handling Building]. The areas to be selected will provide suitable radiation shielding and environmental conditions for the equipment consistent with instrument manufacturer's recommendations. Equipment and cabling for power supplies and indication for each channel will be separated equivalent to that provided for redundant safety related services.

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/placement of the primary and back-up SFP level sensor, and the proposed routing of the cables that will extend from the sensors toward the location of the read-out/display device.

3.3 Mounting The DIP states, in part, that:

Design of the mounting of the sensors in the SFP shall be consistent with the seismic Class I criteria. Installed equipment will be verified to be seismically adequate for the seismic motions associated with the maximum seismic ground motion considered in the design of the plant area in which it is installed.

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 structures for 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/mounting or electrical connections.

(c) A description of the manner by which the mechanical connections will attach the level instrument to permanent SFP structures so as to support the level sensor assembly.

3.4 Qualification The DIP states, in part, that:

Temperature, humidity and radiation levels consistent with conditions in the vicinity of the SFP and the area of use considering normal operational, event and post-event conditions for no fewer than seven days post-event or until off-site resources can be deployed by the

-4 mitigating strategies resulting from Order EA-12-049 will be addressed in the detailed desi~ln phase of the project. Examples of post-event (beyond-design-basis) conditions to be considered are:

radiological conditions for a normal refueling quantity of freshly discharged (100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />) fuel with the SFP water level 3 as described in Order EA-12-0S1,

• temperature of 212 degrees F and 100% relative humidity environment, boiling water and/or steam environment,

• a concentrated borated water environment, and

• the impact of FLEX mitigating strategies [diverse and flexible coping strategies].

For seismic effects on instrument channel components used after a potential seismic event for only installed components (with the exception of battery chargers and replaceable batteries), the following measures will be used to verify that the design and installation is adequate. Applicable components are rated by the manufacturer (or otherwise tested) for seismic effects at levels commensurate with those of postulated design basis event conditions in the area of instrument channel component use using one or more of the following methods:

instrument channel components use known operating principles and are supplied by manufacturers with commercial quality programs (such as IS09001). The procurement speci"fication and/or instrument channel design shall include the seismic requirements and specify the need for commercial design and testing under seismic loadings consistent with design basis values at the installed locations;

• substantial history of operational reliability in environments with significant vibration, such as for portable hand-held devices or transportation applications. Such a vibration design envelope shall be inclusive of the effects of seismic motion imparted to the components proposed at the location of the proposed installation; adequacy of seismic design and installation is demonstrated based on the guidance in Sections 7, 8, 9, and 10 of IEEE [Institute of Electrical and Electronics Engineers]

Standard 344-2004, "IEEE Recommended Practice for Seismic Qualification of Class 1 E Equipment for Nuclear Power Generating Stations," or a substantially similar industrial standard;

• demonstration that proposed devices are substantially similar in design to models that have been previously tested for seismic effects in excess of the plant design basis at the location where the instrument is to be installed (g-Ievels and frequency ranges); or

• seismic qualification using seismic motion consistent with that of existing design basis loading at the installation location.

RAI-4

Please provide the following:

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

- 5 (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 reliability demonstration as it applies to a) the level sensor mounted in the SFP area, and b) any control boxes, electronics, or read-out and re-transmitting devices that will be employed to convey the level information from the level sensor to the plant operators or emergency responders.

(c) A description of the specific method or combination of methods that will be used to confirm the reliability of the permanently installed equipment such that following a seismic event the instrument will maintain its required accuracy.

3.5 Independence The 01 P states, in part, that:

The primary instrument channel will be independent of the backup instrument channel.

This independence will be achieved through physical and electrical separation of each channels' components commensurate with hazard and electrical isolation needs.

RAI-5

Please provide the following:

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

(b) Further information on how each level measurement system, consisting of level sensor electronics, cabling, and readout devices will be designed and installed to address independence through the application and selection of independent power sources, the use of physical and spatial separation, independence of signals sent to the location(s) of the readout devices, and the independence of the displays.

3.6 Power supplies The OIP states, in part, that:

Each channel will be normally powered from a different 120Vac [120 volts-alternating current] bus. Upon loss of normal ac power, individual channel installed batteries will automatically maintain continuous channel operation. The batteries will be replaceable and be sized to maintain channel operation until off-site resources can be deployed by the mitigating strategies resulting from Order EA-12-049. Additionally, each channel wi!ll have provisions for connection to another suitable power source.

RAI-6

If the level measurement channels are to be powered through a battery system (either directly or through an uninterruptible power supply), please provide the design criteria that will be

- 6 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 beyond-design-basis event for the minimum duration needed, consistent with the plant mitigation strategies for beyond design-basis external events (Order EA-12-049).

3.7 Accuracy The OIP states, in part, that:

The instrument channels will be designed to maintain their design accuracy following a power interruption or change in power source without recalibration. Instrument channel accuracy, to be determined during detailed design, will consider Spent Fuel Pool conditions (e.g., saturated water, steam environment, concentrated borated water), as well as, other applicable radiological and environmental conditions and include display accuracy. Instrument channel accuracy will be sufficient to allow trained personnel to determine when the actual level exceeds the specified lower level of each indicating range (levels 1, 2 or 3) without conflicting or ambiguous indications.

RAI-7

Please provide the following:

(a) An estimate of the expected instrument channel accuracy performance under both (a) normal SFP level conditions (approximately Level 1 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 accuracy that will be employed under normal operating conditions as an acceptance criterion for a calibration procedure to flag to operators and to technicians that the channel requires adjustment to within the normal condition design accuracy_

3.8 Testing The OIP states, in part, that Instrument channel design will provide for routine testing and calibration consistent with the guidelines of NRC JLD-ISG-2012-03 and NEI12-02. Details will be determined during detailed design engineering.

RAI-8

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 capability enables the equipment to be tested in-situ.

-7 (b) A description of how such testing and calibration will enable the conduct of regular channel checks of each independent channel against the other, and against any other permanently-installed SFP level instrumentation.

(c) A description of how functional checks will be performed, and the frequency at which they will be conducted. Describe how calibration tests will be performed and the frequency at which they will be conducted. Provide a discussion as to how these surveillances will be incorporated 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 is necessary to ensure that the channels are fully conditioned to accurately and reliably perform their functions when needed.

3.9 Display The 01 P states, in part, that:

The primary and backup instrument displays will be located at the control room, alternate shutdown panel, or other appropriate and accessible location. The specific location will be determined during detailed design. An appropriate and accessible location will include the following characteristics:

• occupied or promptly accessible to the appropriate plant staff giving appropriate consideration to various drain down scenarios, outside the area surrounding the SFP floor (e.g., an appropriate distance from the radiological sources resulting from an event impacting the Spent Fuel Pool),

inside a structure providing protection against adverse weather, and outside of any very high radiation areas or LOCKED HIGH RAD AREA during norm.al operation.

RAI-9

Please provide the following:

(a) The specific location for each of the primary and backup instrument channel displays.

(b) If the primary and backup display location is other than the main control room, provide justification for prompt accessibility to displays including primary and alternate route evaluation, habitability at display location(s), continual resource availability for personnel.

responsible to promptly read displays, and provisions for communications with decision makers for the various SFP drain down scenarios and external events.

(c) The reasons justifying why the locations selected enable the information from these instruments to be considered "promptly accessible" to various drain-down scenarios and external events.

- 8 4.0 PROGRAM FEATURES 4.2 Procedures The OIP states, in part, that:

Procedures will be developed using guidelines and vendor instructions to address the maintenance, operation and abnormal response issues associated with the primary and backup channels of Spent Fuel Pool instrumentation.

RAI-10

Please provide a description of the standards, guidelines and/or criteria that will be utilized to develop procedures for inspection, maintenance, repair, operation, abnormal response, and administrative controls associated with the SFP level instrumentation, as well as storage and installation of portable instruments.

4.3 Testing and Calibration The OIP states, in part, that:

The testing and calibration of the instrumentation will be consistent with vendor recommendations or other documented basis. Calibration will be specific to the mounted instruments and the displays. Calibration will be performed to an Instrument Maintenance Procedure (BIP/BISR series). A Passport PMID will be used to direct frequency tor performance of the instrument calibration.

RAI-11

Please provide the following:

(a) Further information describing the maintenance and testing program the licensee will establish and implement to ensure that regular testing and calibration is performed and verified by inspection and audit to demonstrate conformance with design and system readiness 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 what compensatory actions are planned in the event that one of the instrument channels cannot be restored to functional status within 90 days.

REQUEST FOR ADDITIONAL INFORMATION OVERALL INTEGRATED PLAN IN RESPONSE TO COMMISSION ORDER MODIFYING LICENSE REQUIREMENTS FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION (ORDER EA-12-051)

EXELON GENERATION COMPANY, LLC CLINTON POWER STATION, UNIT NO.1 DOCKET NO. 50-461

1.0 INTRODUCTION

By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13059A306), Exelon Generation Company, LLC submitted an overall integrated plan (OIP) in response to the March 12, 2012, U.S. Nuclear Regulatory Commission (NRC) Order modifying licenses with regard to reliable spent fuel pool (SFP) instrumentation (Order EA-12-051; ADAMS Accession No. ML12054A679) for Clinton Power Station, Unit No.1. The NRC staff endorsed Nuclear Energy Institute, NE112-02, "Industry Guidance for Compliance with NRC Order EA-12-051, to Modify Licenses with Regard to Reliable SFP Instrumentation," Revision 1, dated August 2012 (ADAMS Accession No. ML12240A307), with exceptions as documented in NRC Interim Staff Guidance, JLD-ISG 2012-03, "Compliance with Order EA-12-051, Reliable Spent Fuel Pool Instrumentation,"

Revision 0, dated August 29,2012 (ADAMS Accession No. ML12221A339).

The NRC staff has reviewed the February 28, 2013, response by the licensee and determined that 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:

Level adequate to support operation of the normal fuel pool cooling system (Level 1): Indicated level on either primary or backup instrument channel of greater than 26 feet 8 Y4 inches (elevation 754') plus instrument accuracy above the top of the storage racks based on the design accuracy of the instrument channel (which is to be determined) and a resolution better than 1 foot for both the primary and backup instrument channels....

- 2 Level adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck (Level 2): Indicated level on primary or backup instrument channel of greater than 10 feet (elevation 737.31') plus instrument channel accuracy above the top of the storage racks based on specification of this level as adequate in NRC JLD-ISG-2012-03 and NEI12-02, the specified design accuracy of the instrument channel, and the relatively low sensitivity of dose rates to changes in water depth at this level.....

Level where fuel remains covered (Level 3): Indicated level on either the primary or backup instrument channel of greater than 0 feet (elevation 727.31') plus instrument channel accuracy above the top of the storage racks based upon the design accuracy (which is to be determined) of the instrument channel for both the primary and backup instrument channels.

RAI-1

Please provide the following:

(a) For Level 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 in the arrangement for the portions of instrument channel consisting of permanent measurement channel equipment (e.g., fixed level sensors and/or stilling wells, and mounting 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 of the level sensor measurement range that is sensitive to measurement of the fuel pool level, with respect to the Level 1, Level 2, and Level 3, datum points.

3.0 INSTRUMENTATION DESIGN FEATURES 3.2 Arrangement The alP states, in part, that:

The current proposed plan is to install SFP level sensors in the southwest corner and 011 the east side of the SFP separated in excess of 20 feet. The sensors themselves will be mounted, to the extent practical, near the pool walls and below the pool curb to minimize their exposure to damaging debris and not interfere with SFP activities. Instrument channel electronics and power supplies will be located in seismic and missile protected areas either below the SFP operating floor or in buildings other than the Fuel Building.

The areas to be selected will provide suitable radiation shielding and environmental conditions for the equipment consistent with instrument manufacturers recommendations. Equipment and cabling for power supplies and indication for each channel will be separated equivalent to that provided for redundant safety related services.

-3

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/placement of the primary and back-up SFP level sensor, and the proposed routing of the cables that will extend from the sensors toward the location of the read-out/display device.

3.3 Mounting The OIP states, in part, that:

Design of the mounting of the sensors in the SFP shall be consistent with the seismic Class I criteria. Installed equipment will be verified to be seismically adequate for the seismic motions associated with the maximum seismic ground motion considered in the design of the plant area in which it is installed.

RAI-3

Please provide the following:

(a) The desjgn 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 structures for 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/mounting or electrical connections.

(c) A description of the manner by which the mechanical connections will attach the level instrument to permanent SFP structures so as to support the level sensor assembly.

3.4 Qualification The OIP states, in part, that:

Components of the instrument channels will be qualified for shock and vibration using one or more of the following methods:

• components are supplied by manufacturers using commercial quality programs (such as IS09001, "Quality management systems - Requirements") with shock and vibration requirements included in the purchase specification at levels commensurate with portable hand-held devices or transportation applications;

• components have substantial history of operational reliability in environments with significant shock and vibration loadings, such as portable hand-held devices or transportation applications; or

-4 components are inherently resistant to shock and vibration loadings, such as cables.

For seismic effects on instrument channel components used after a potential seismic event for only installed components (with the exception of battery chargers and replaceable batteries), the following measures will be used to verify that the design and installation is adequate. Applicable components are rated by the manufacturer (or otherwise tested) for seismic effects at levels commensurate with those of postulated design basis event conditions in the area of instrument channel component use using one or more of the following methods:

instrument channel components use known operating principles and are supplied by manufacturers with commercial quality programs (such as IS09001). The procurement specification and/or instrument channel design shall include the seismic requirements and specify the need for commercial design and testing under seismic loadings consistent with design basis values at the installed locations; substantial history of operational reliability in environments with significant vibration, such as for portable hand-held devices or transportation applications. Such a vibration design envelope shall be inclusive of the effects of seismic motion imparted to the components proposed at the location of the proposed installation;

• adequacy of seismic design and installation is demonstrated based on the guidance in Sections 7,8,9, and 10 of IEEE [Institute of Electrical and Electronics Engineers]

Standard 344-2004, "I EEE Recommended Practice for Seismic Qualification of Class 1 E Equipment for Nuclear Power Generating Stations," or a substantially similar industrial standard;

• demonstration that proposed devices are substantially similar in design to models that have been previously tested for seismic effects in excess of the plant design basis at the location where the instrument is to be installed (g-Ievels and frequency ranges); or

• seismic qualification using seismic motion consistent with that of existing design basis loading at the installation location.

RAI-4

Please provide the following:

(a) A description of the specific method or combination of methods you intend to apply to demonstrate the reliability of the permanently installed equipment under beyond-design basis ambient temperature, humidity, shock, vibration, and radiation 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 basis loading at the location where the equipment will be mounted. Include a discussion of this seismic reliability demonstration as it applies to (a) the level sensor mounted in the SFP area, and (b) any control boxes, electronics, or read-out and re-transmitting devices that will be employed to convey the level information from the level sensor to the plant operators or emergency responders.

- 5 (c) A description of the specific method or combination of methods that will be used to confirm the reliability of the permanently installed equipment such that following a seismic event the instrument will maintain its required accuracy.

3.5 Independence The OIP states, in part, that:

The primary instrument channel will be independent of the backup instrument channel.

This independence will be achieved through physical and electrical separation of each channels' components commensurate with hazard and electrical isolation needs.

RAI-5

Please provide the following:

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

(b) Further information on how each level measurement system, consisting of level sensor electronics, cabling, and readout devices will be designed and installed to address independence through the application and selection of independent power sources, the use of physical and spatial separation, independence of signals sent to the location(s) of the readout devices, and the independence of the displays.

3.6 Power supplies The OIP states, in part, that:

Each channel will be normally powered from a different 120Vac [120 volts-alternating current] bus. Upon loss of normal ac power, individual channel installed batteries will automatically maintain continuous channel operation. The batteries will be replaceable and be sized to maintain channel operation until off-site resources can be deployed by the mitigating strategies resulting from Order EA-12-049. Additionally, each channel will have provisions for connection to another suitable power source.

RAI-6

If the level measurement channels are to be powered through a battery system (either directly or through an uninterruptible power supply), 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 beyond-design-basis event for the minimum duration needed, consistent with the plant mitigation strategies for beyond design-basis external events (Order EA-12-049).

- 6 3.7 Accuracy The 01 P states, in part, that:

The instrument channels will be designed to maintain their design accuracy following a power interruption or change in power source without recalibration. Instrument channel accuracy, to be determined during detailed design, will consider Spent Fuel Pool conditions (e.g., saturated water, steam environment, etc), as well as, other applicable radiological and environmental conditions and include display accuracy. Instrument channel accuracy will be sufficient to allow trained personnel to determine when the actual level exceeds the specified lower level of each indicating range (Levels 1, 2, or 3) without conflicting or ambiguous indications.

RAI-7

Please provide the following:

(a) An estimate of the expected instrument channel accuracy performance under both (a) normal SFP level conditions (approximately Level 1 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 accuracy that will be employed under normal operating conditions as an acceptance criterion for a calibration procedure to fla!~

to operators and to technicians that the channel requires adjustment to within the normal condition design accuracy.

3.8 Testing The OIP states, in part, that:

Instrument channel design will provide for routine testing and calibration consistent with the guidelines of NRC JLD-ISG-2012-03 and NEI 12-02. Details will be determined during detailed design engineering.

RAI-8

Please provide the following:

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

(b) A description of how such testing and calibration will enable the conduct of regular channel checks of each independent channel against the other, and against any other permanently-installed SFP level instrumentation.

- 7 (c) A description of how functional checks will be performed, and the frequency at which they will be conducted. Describe how calibration tests will be performed, and the frequency at which they will be conducted. Provide a discussion as to how these surveillances will be incorporated 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 is necessary to ensure that the channels are fully conditioned to accurately and reliably perform their functions when needed.

3.9 Display The OIP states, in part, that:

The primary and backup instrument displays will be located at the control room, alternate shutdown panel, or other appropriate and accessible location. The specific location will be determined during detailed design.

RAI-9

Please provide the following:

(a) The specific location for each of the primary and backup instrument channel displays.

(b) If the primary and backup display location is other than the main control room, provide justification for prompt accessibility to displays including primary and alternate route evaluation, habitability at display location(s), continual resource availability for personnel responsible to promptly read displays, and provisions for communications with decision makers for the various SFP drain down scenarios and external events.

(c) The reasons justifying why the locations selected enable the information from these instruments to be considered "promptly accessible" to various drain-down scenarios and external events.

4.0 PROGRAM FEATURES 4.2 Procedures The OIP states, in part, that:

Procedures will be developed using guidelines and vendor instructions to address the maintenance, operation and abnormal response issues associated with the primary and backup channels of SFP instrumentation.

RAI-10

Please provide a description of the standards, guidelines and/or criteria that will be utilized to develop procedures for inspection, maintenance, repair, operation, abnormal response, and administrative controls associated with the SFP level instrumentation, as well as storage and installation of portable instruments.

- 8 4.3 Testing and Calibration The OIP states, in part, that:

The testing and calibration of the instrumentation will be consistent with vendor recommendations or other documented basis. Calibration will be specific to the mounted instruments and the displays as determined during the modification review process.

RAI-11

Please provide the following:

(a) Further information describing the maintenance and testing program the licensee will establish and implement to ensure that regular testing and calibration is performed and verified by inspection and audit to demonstrate conformance with design and system readiness 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 what compensatory actions are planned in the event that one of the instrument channels cannot be restored to functional status within 90 days.

REQUEST FOR ADDITIONAL INFORMATION OVERALL INTEGRATED PLAN IN RESPONSE TO COMMISSION ORDER MODIFYING LICENSE REQUIREMENTS FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION (ORDER EA-12-051)

EXELON GENERATION COMPANY, LLC LASALLE COUNTY STATION, UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-374

1.0 INTRODUCTION

By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13063A323). Exelon Generation Company. LLC submitted an overall integrated plan (OIP) in response to the March 12, 2012, U.S. Nuclear Regulatory Commission (NRC) Order modifying licenses with regard to reliable spent fuel pool (SFP) instrumentation (Order EA-12-051; ADAMS Accession No. ML12054A679) for LaSalle County Station, Units 1 and 2. The NRC staff endorsed Nuclear Energy Institute, NEI 12-02. "Industry Guidance for Compliance with NRC Order EA-12-051, to Modify Licenses with Regard to Reliable SFP Instrumentation," Revision 1. dated August 2012 (ADAMS Accession No. ML12240A307), with exceptions as documented in NRC Interim Staff Guidance, JLD-ISG 2012-03. "Compliance with Order EA-12-051. Reliable Spent Fuel Pool Instrumentation,"

Revision 0, dated August 29,2012 (ADAMS Accession No. ML12221A339).

The NRC staff has reviewed the February 28, 2013, response by the licensee and determined that 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:

Level adequate to support operation of the normal fuel pool cooling system (Level 1): For both units, indicated level on either primary or backup instrument channel must be greater than 842' 1 II to maintain normal operation of the Fuel Pool Cooling system. 842' 1 II is the elevation of the bottom of the fuel pool weirs which maintain the flowpath for re-circulation of water from the pool through the system.

Level adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck (Level 2): For both units, indicated level on either the primary or backup instrument channel of greater than 10 feet plus

- 2 instrument channel accuracy above the top of the storage racks. The specification of this level is based on JLD-ISG-2012-03 and NEI12-02. This monitoring level ensures there is an adequate water level to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck from direct gamma radiation from stored fuel.

Level where fuel remains covered (Level 3): For both units, indicated level on either the' primary or backup instrument channel of greater than 0 feet (elevation 820') plus instrument channel accuracy above the top of the storage racks based upon the design accuracy (which is to be determined) of the instrument channel for both the primary and backup instrument channels. This monitoring level assures that water is covering the stored fuel seated in the racks.

RAI-1

Please provide the following:

(a) For Level 1, specify how the identified location represents the higher of the two points described in the NE112-02 guidance for this level.

(b) A clearly labeled sketch depicting the elevation view of the proposed typical mounting arrangement for the portions of instrument channel consisting of permanent measurement channel equipment (e.g., fixed level sensors and/or stilling wells, and mounting 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 of the level sensor measurement range that is sensitive to measurement of the fuel pool level, with respect to the Level 1, Level 2, and Level 3, datum points.

3.0 INSTRUMENTATION DESIGN FEATURES 3.2 Arrangement The OIP states, in part, that:

The plan is to install SFP level sensors in the southeast corner of the Unit 1 SFP and in the northeast corner of the Unit 2 SFP; separated by a distance of approximately 103 feet. The sensors themselves will be mounted, to the extent practical, near the pool walls and below the pool curb to minimize their exposure to damaging debris and not interfere with SFP activities. Instrument channel electronics and power supplies will be located in seismic and missile protected areas either below the SFP operating floor or in buildings other than the RB

[Reactor Building]. The areas to be selected will provide suitable radiation shielding and environmental conditions for the equipment consistent with instrument manufacturer's recommendations. Equipment and cabling for power supplies and indication for each channel will be separated equivalent to that provided for redundant safety related services.

- 3

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/placement of the primary and back-up SFP level sensor, and the proposed routing of the cables that will extend from the sensors toward the location of the read-out/display device.

3.3 Mounting The OIP states, in part, that:

Design of the mounting of the sensors in the SFP shall be consistent with the seismic Class I criteria. Installed equipment will be verified to be seismically adequate for the seismic motions associated with the maximum seismic ground motion considered in the design of the plant area in which it is installed.

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) willi be attached to the refueling floor and/or other support structures for 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/mounting or electrical connections.

(c) A description of the manner by which the mechanical connections will attach the level instrument to permanent SFP structures so as to support the level sensor assembly.

3.4 Qualification The OIP states, in part, that:

Components of the instrument channels will be qualified for shock and vibration using one or more of the following methods:

• components are supplied by manufacturers using commercial quality programs (such as IS09001, "Quality management systems - Requirements") with shock and vibration requirements included in the purchase specification at levels commensurate with portable hand-held devices or transportation applications; and/or

-4

• components have substantial history of operational reliability in environments with significant shock and vibration loadings, such as portable hand-held devices or transportation applications; and/or components are inherently resistant to shock and vibration loadings, such as cables.

For seismic effects on instrument channel components used after a potential seismic event for only installed components (with the exception of battery chargers and replaceable batteries), the following measures will be used to verify that the design and installation is adequate. Applicable components are rated by the manufacturer (or otherwise tested) for seismic effects at levels commensurate with those of postulated design basis event conditions in the area of instrument channel component use using one or more of the following methods:...

RAI-4

Please provide the following:

(a) A description of the specific method or combination of methods you intend to apply to demonstrate the reliability of the permanently installed equipment under beyond-design-*

basis ambient temperature, humidity, shock, vibration, and radiation 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 basis loading at the location where the equipment will be mounted. Include a discussion of this seismic reliability demonstration as it applies to (a) the level sensor mounted in the SFP area, and (b) any control boxes, electronics, or read-out and re-transmitting devices that will be employed to convey the level information from the level sensor to the plant operators or emergency responders.

(c) A description of the specific method or combination of methods that will be used to confirm the reliability of the permanently installed equipment such that following a seismic event the instrument will maintain its required accuracy.

3.5 Independence The OIP states, in part, that:

The primary instrument channel will be independent of the backup instrument channel.

This independence will be achieved through physical and electrical separation of each channels' components commensurate with hazard and electrical isolation needs.

- 5

RAI-5

Please provide the following:

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

(b) Further information on how each level measurement system, consisting of level sensor electronics, cabling, and readout devices will be designed and installed to address independence through the application and selection of independent power sources, the use of physical and spatial separation, independence of signals sent to the location{s) of the readout devices, and the independence of the displays.

3.6 Power supplies The OIP states, in part, that:

Each channel will be normally powered from a different 120Vac [120 volts-alternating current] bus. Upon loss of normal ac power, individual channel installed batteries will automatically maintain continuous channel operation. The batteries will be replaceable and be sized to maintain channel operation until off-site resources can be deployed by the mitigating strategies resulting from Order EA-12-049. Additionally, each channel will have provisions for connection to another suitable power source.

RAI-6

If the level measurement channels are to be powered through a battery system (either directly or through an uninterruptible power supply), 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 beyond-design-basis event for the minimum duration needed, consistent with the plant mitigation strategies for beyond design-basis external events (Order EA-12-049).

3.7 Accuracy The 01 P states, in part, that:

The instrument channels will be designed to maintain their design accuracy following a power interruption or change in power source without recalibration. Instrument channel accuracy, to be determined during detailed design, will consider Spent Fuel Pool conditions (e.g., saturated water, steam environment), as well as, other applicable radiological and environmental conditions and include display accuracy. Instrument channel accuracy will be sufficient to allow trained personnel to determine when the actual level exceeds the specified lower level of each indicating range (Levels 1, 2 or 3) without conflicting or ambiguous indications.

- 6

RAI-7

Please provide the following:

(a) An estimate of the expected instrument channel accuracy performance under both a) normal SFP level conditions (approximately Level 1 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 accuracy that will be employed under normal operating conditions as an acceptance criterion for a calibration procedure to flalg to operators and to technicians that the channel requires adjustment to within the normal condition design accuracy.

3.8 Testing The OIP states, in part, that:

Instrument channel design will provide for routine testing and calibration consistent with the guidelines of NRC JLD-ISG-2012-03 and NEI12-02. Details will be determined during detailed design engineering.

RAI-8

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 capability enables the equipment to be tested in-situ.

(b) A description of how such testing and calibration will enable the conduct of regular channel checks of each independent channel against the other, and against any other permanently-installed SFP level instrumentation.

(c) A description of how functional checks will be performed, and the frequency at which they will be conducted. Describe how calibration tests will be performed, and the frequency at which they will be conducted. Provide a discussion as to how these surveillances will be incorporated 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 is necessary to ensure that the channels are fully conditioned to accurately and reliably perform their functions when needed.

- 7 3.9 Display The OIP states, in part, that:

The primary and backup instrument displays will be located at the control room, remote shutdown panel, or other appropriate and accessible location. The specific location will be determined during detailed design.

RAI-9

Please provide the following:

(a) The specific location for each of the primary and backup instrument channel displays.

(b) If the primary and backup display location is other than the main control room, provide justification for prompt accessibility to displays including primary and alternate route evaluation, habitability at display location(s), continual resource availability for personnel responsible to promptly read displays, and provisions for communications with decision makers for the various SFP drain down scenarios and external events.

(c) The reasons justifying why the locations selected enable the information from these instruments to be considered "promptly accessible" to various drain-down scenarios and external events.

4.0 PROGRAM FEATURES 4.2 Procedures The 01 P states, i!1 part, that:

Procedures will be developed using guidelines and vendor instructions to address the maintenance, operation and abnormal response issues associated with the primary and backup channels of SFP instrumentation.

RAI-10

Please provide a description of the standards, guidelines and/or criteria that will be utilized to develop procedures for inspection, maintenance, repair, operation, abnormal response, and administrative controls associated with the SFP level instrumentation, as well as storage and installation of portable instruments.

4.3 Testing and Calibration The OIP states, in part, that:

Processes shall be established and maintained for scheduling and implementing necessary testing and calibration of the primary and backup SFP level instrument channels to maintain the instrument channels at the design accuracy. The testing and calibration of the instrumentation shall be consistent with vendor

- 8 recommendations or other documented basis. Calibration shall be specific to the mounted instrument and the monitor.

Surveillances or testing to validate functionality of an installed instrument channel shall be performed within 60 days of a planned refueling outage considering normal testing scheduling allowances (e.g., 25%). This is not required to be performed more than once per 12 months.

RAI-11

Please provide the following:

(a) Further information describing the maintenance and testing program the licensee will establish and implement to ensure that regular testing and calibration is performed and verified by inspection and audit to demonstrate conformance with design and system readiness 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 what compensatory actions are planned in the event that one of the instrument channels cannot be restored to functional status within 90 days.

REQUEST FOR ADDITIONAL INFORMATION OVERALL INTEGRATED PLAN IN RESPONSE TO COMMISSION ORDER MODIFYING LICENSE REQUIREMENTS FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION (ORDER EA-12-051)

EXELON GENERATION COMPANY, LLC QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-254 AND 50-265

1.0 INTRODUCTION

By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13060A124), Exelon Generation Company, LLC submitted an overall integrated plan (OIP) in response to the March 12, 2012, U.S. Nuclear Regulatory Commission (NRC) Order modifying licenses with regard to reliable spent fuel pool (SFP) instrumentation (Order EA-12-051 ; ADAMS Accession No. ML12054A679) for Quad Cities Nuclear Power Station, Units 1 and 2. The NRC staff endorsed Nuclear Energy Institute, NEI12-02, "Industry Guidance for Compliance with NRC Order EA-12-051, to Modify Licenses with Regard to Reliable SFP Instrumentation," Revision 1, dated August 2012 (ADAMS Accession No. ML12240A307). with exceptions as documented in NRC Interim Staff Guidance, JLD-ISG-2012-03, "Compliance with Order EA-12-051. Reliable Spent Fuel Pool Instrumentation." Revision 0, dated August 29,2012 (ADAMS Accession No. ML12221A339).

The NRC staff has reviewed the February 28. 2013, response by the licensee and determined that 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:

Level adequate to support operation of the normal fuel pool cooling system (L 1):

For both units, indicated level on either primary or backup instrument channel must be greater than 23 feet 1 inch (elevation 689' 3") plus instrument accuracy above the top of the storage racks based on the design accuracy of the instrument channel (which is to be determined) and a resolution of 1 foot or better for both the primary and backup instrument channels. This is based on the 11 inch opening of the SFP weir gate design demonstrating a water level above 23 feet 1 inch (elevation 689' 3") is adequate for normal fuel pool cooling system operation

- 2 Level adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck (L2): For both units, indicated level on either the primary or backup instrument channel of greater than 10 feet (elevation 676' 2") plus instrument channel accuracy above the top of the storage racks based on specification of this level as adequate in NRC JLD-ISG-2012-03 (Ref. 2) and NEI 12-02 (Ref. 3), the specified design accuracy of the instrument channel, and the relatively low sensitivity of dose rates to changes in water depth at this level.

This monitoring level ensures there is an adequate water level to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck from direct gamma radiation from stored spent fuel.

Level where fuel remains covered (L3): For both units, indicated level on either the primary or backup instrument channel of greater than 0 feet (elevation 666' 2") plus instrument channel accuracy above the top of the storage racks based upon the design accuracy (which is to be determined) of the instrument channel for both the primary and backup instrument channels. This monitoring level assures that water is covering the stored fuel seated in the racks.

RAI-1

Please provide the following:

(a) For Level L 1, specify how the identified location represents the higher of the two points described in the NEI 12-02 guidance.

(b) A clearly labeled sketch depicting the elevation view of the proposed typical mounting arrangement for the portions of instrument channel consisting of permanent measurement channel equipment (e.g., fixed level sensors and/or stilling wells, and mounting brackets). Indicate on this sketch the datum values representing Level L 1, Level L2, and Level L3, as well as the top of the fuel. Indicate on this sketch the portion of the level sensor measurement range that is sensitive to measurement of the fuel pool level, with respect to Level L 1, Level L2, and Level L3 datum points.

3.0 INSTRUMENTATION DESIGN FEATURES 3.2 Arrangement The OIP states, in part, that:

The current plan is to install SFP level sensors in the southwest corner of the Unit 1 SFP and in the northwest corner of the Unit 2 SFP separated by a distance in excess of 50 feet. The sensors themselves will be mounted, to the extent practical, near the pool walls and below the pool curb to minimize their exposure to damaging debris and not interfere with SFP activities. Instrument channel electronics and power supplies will be located in seismic and missile protected areas either below the SFP operating floor or in buildings other than the RB [Reactor Building]. The areas to be selected will provide suitable radiation shielding and environmental conditions for the equipment consistent with instrument manufacturer's recommendations. Equipment and cabling for power

- 3 supplies and indication for each channel will be separated equivalent to that provided for redundant safety related services as required by the Quad Cities design basis.

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/placement of the primary and back-up SFP level sensor, and the proposed routing of the cables that will extend from the sensors toward the location of the read-out/display device.

3.3 Mounting The 01 P states, in part, that:

Design of the mounting of the sensors in the SFP shall be consistent with the seismic Class I criteria. Installed equipment will be verified to be seismically adequate for the seismic motions associated with the maximum seismic ground motion considered in the design of the plant area in which it is installed.

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 structures for 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/mounting or electrical connections.

(c) A description of the manner by which the mechanical connections will attach the level instrument to permanent SFP structures so as to support the level sensor assembly.

3.4 Qualification The OIP states, in part, that:

Components of the instrument channels will be qualified for shock and vibration using one or more of the following methods:

components are supplied by manufacturers using commercial quality programs (such as IS09001, "Quality management systems - Requirements") with shock and vibration requirements included in the purchase specification at levels commensuratl;:!

with portable hand-held devices or transportation applications;

- 4 components have substantial history of operational reliability in environments with significant shock and vibration loadings, such as portable hand-held devices or transportation applications; or components are inherently resistant to shock and vibration loadings, such as cables, For seismic effects on instrument channel components used after a potential seismic event for only installed components (with the exception of battery chargers and replaceable batteries), the following measures will be used to verify that the design and installation is adequate. Applicable components are rated by the manufacturer (or otherwise tested) for seismic effects at levels commensurate with those of postulated design basis event conditions in the area of instrument channel component use using one or more of the following methods:

instrument channel components use known operating principles and are supplied by manufacturers with commercial quality programs (such as IS09001). The procurement specification and/or instrument channel design shall include the seismk:

requirements and specify the need for commercial design and testing under seismic loadings consistent with design basis values at the installed locations; substantial history of operational reliability in environments with significant vibration, such as for portable hand-held devices or transportation applications. Such a vibration design envelope shall be inclusive of the effects of seismic motion imparted to the components proposed at the location of the proposed installation; adequacy of seismic design and installation is demonstrated based on the guidance in Sections 7,8,9, and 10 of IEEE [Institute of Electrical and Electronics Engineers]

Standard 344-2004, "IEEE Recommended Practice for Seismic Qualification of Class 1 E Equipment for Nuclear Power Generating Stations," or a substantially similar industrial standard; demonstration that proposed devices are substantially similar in design to models that have been previously tested for seismic effects in excess of the plant design basis at the location where the instrument is to be installed (g-Ievels and frequency ranges); or

• seismic qualification using seismic motion consistent with that of existing design basis loading at the installation location.

RAI-4

Please provide the following:

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

(b) A description of the testing and/or analyses that will be conducted to provide assurance that 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 reliability demonstration as it applies to a) the level sensor mounted in the SFP area, and b) any control boxes, electronics, or read-out and re-transmitting devices that

- 5 will be employed to convey the level information from the level sensor to the plant operators or emergency responders.

(c) A description of the specific method or combination of methods that will be used to confirm the reliability of the permanently installed equipment such that following a seismic event the instrument will maintain its required accuracy.

3.5 Independence The OIP states, in part, that:

The primary instrument channel will be independent of the backup instrument channel.

This independence will be achieved through physical and electrical separation of each channels' components commensurate with hazard and electrical isolation needs.

RAI-5

Please provide the following:

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

(b) Further information on how each level measurement system, consisting of level sensor electronics, cabling, and readout devices will be designed and installed to address independence through the application and selection of independent power sources, the use of physical and spatial separation, independence of signals sent to the location(s) of the readout devices, and the independence of the displays.

3.6 Power supplies The OIP states, in part, that:

Each channel will be normally powered from a different 120Vac [120 volts-alternating current] bus. Upon loss of normal ac power, individual channel installed batteries will automatically maintain continuous channel operation. The batteries will be replaceable and be sized to maintain channel operation until off-site resources can be deployed by the mitigating strategies resulting from Order EA-12-049 (Ref. 4). Additionally, each channel will have provisions for connection to another suitable power source.

RAI-6

If the level measurement channels are to be powered through a battery system (either directly or through an uninterruptible power supply), 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 beyond-design-basis event for the minimum duration needed, consistent with the plant mitigation strategies for beyond design-basis external events (Order EA-12-049).

- 6 3.7 Accuracy The OIP states, in part, that:

The instrument channels will be designed to maintain their design accuracy following a power interruption or change in power source without recalibration. Instrument channel accuracy, to be determined during detailed design, will consider Spent Fuel Pool conditions (e.g., saturated water, steam environment, concentrated borated water), as well as, other applicable radiological and environmental conditions and include display accuracy. Instrument channel accuracy will be sufficient to allow trained personnel to determine when the actual level exceeds the specified lower level of each indicating range (levels 1, 2 or 3) without conflicting or ambiguous indications.

RAI-7

Please provide the following:

(a) An estimate of the expected instrument channel accuracy performance under both (a) normal SFP level conditions (approximately Level L 1 or higher) and (b) at the beyond design-basis conditions (Le., radiation, temperature, humidity, post-seismic and post shock conditions) that would be present if the SFP level were at the Level L2 and Level L3, datum points.

(b) A description of the methodology that will be used for determining the maximum allowed deviation from the instrument channel design accuracy that will be employed under normal operating conditions as an acceptance criterion for a calibration procedure to flag to operators and to technicians that the channel requires adjustment to within the normal condition design accuracy.

3.8 Testing The OIP states, in part, that:

Instrument channel design will provide for routine testing and calibration consistent with the guidelines of NRC JLD-ISG-2012-03 (Ref. 2) and NEI 12-02 (Ref. 3). Details will be determined during detailed design engineering.

RAI-8

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 capability enables the equipment to be tested in-situ.

(b) A description of how such testing and calibration will enable the conduct of regular channel checks of each independent channel against the other, and against any other permanently-installed SFP level instrumentation.

- 7 (c) A description of how functional checks will be performed, and the frequency at which they will be conducted. Describe how calibration tests will be performed, and the frequency at which they will be conducted. Provide a discussion as to how these surveillances will be incorporated 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 is necessary to ensure that the channels are fully conditioned to accurately and reliably perform their functions when needed.

3.9 Display The alP states, in part, that:

The primary and backup instrument displays will be located at the control room, alternate shutdown panel, or other appropriate and accessible location. The specific location will be determined during detailed design. An appropriate and accessible location will include the following characteristics:

• occupied promptly accessible to the appropriate plant staff giving appropriate consideration to various drain down scenarios,

• outside the area surrounding the SFP floor (e.g., an appropriate distance from the radiological sources resulting from an event impacting the Spent Fuel Pool),

inside a structure providing protection against adverse weather, and

• outside of any Very High radiation areas or LOCKED HIGH RAD AREA during normal operation.

RAI-9

Please provide the following:

(a) The specific location for each of the primary and backup instrument channel displays.

(b) If the primary and backup display location is other than the main control room, provide justification for prompt accessibility to displays including primary and alternate route evaluation, habitability at display location(s), continual resource availability for personnel responsible to promptly read displays, and provisions for communications with decision makers for the various SFP drain down scenarios and external events.

(c) The reasons justifying why the locations selected enable the information from these instruments to be considered "promptly accessible" to various drain-down scenarios and external events.

- 8 4.0 PROGRAM FEATURES 4.2 Procedures The DIP states, in part, that:

Procedures will be developed using guidelines and vendor instructions to address the maintenance, operation and abnormal response issues associated with the primary ancl backup channels of SFP instrumentation.

RAI-10

Please provide a description of the standards, guidelines and/or criteria that will be utilized to develop procedures for inspection, maintenance, repair, operation, abnormal response, and administrative controls associated with the SFP level instrumentation, as well as storage and installation of portable instruments.

4.3 Testing and Calibration The DIP states, in part, that:

The testing and calibration of the instrumentation will be consistent with vendor recommendations or other documented basis. Calibration will be specific to the mounted instruments and the displays. Instrument performance will be trended as described in Exelon procedural requirements.

RAI-11

Please provide the following:

(a) Further information describing the maintenance and testing program the licensee will establish and implement to ensure that regular testing and calibration is performed and verified by inspection and audit to demonstrate conformance with design and system readiness requirements. Include a description of your plans for ensuring that necessary channel checks, functional tests, periodic calibration, and maintenance will be conductE~d 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 what compensatory actions are planned in the event that one of the instrument channels cannot be restored to functional status within 90 days.

. ML13134A093 OFFICE LPL3-2/PM LPL3-2/LA LPL3-2/BC NAME BPurnel1 SRohrer

,I Bowen DATE 6/5/13 6/4/13 6/7/13 OFFICE DS/SBPB DE/EICB LPL3-2/PM NAME GCasto

-!Thorp BPurnel1 DATE 6/6/13

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