TMI-13-095, Response to Request for Additional Information - Overall Integrated Plan in Response to Commission Order Modifying License Requirements for Reliable Spent Fuel Pool Instrumentation (Order No. EA-12-051)
| ML13205A305 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 07/24/2013 |
| From: | David Helker Exelon Generation Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| EA-12-051, TMI-13-095 | |
| Download: ML13205A305 (14) | |
Text
RS-13-182 TM!-13-095 Order No. EA-12-051 July 24, 2013 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 NRC Docket No. 50-289
Subject:
Response to Request for Additional Information - Overall Integrated Plan in Response to Commission Order Modifying License Requirements for Reliable Spent Fuel Pool Instrumentation (Order No. EA-12-051)
References:
- 1. Exelon Generation Company, LLC letter to USNRC, Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051 ), dated February 28, 2013 (RS-13-036)
- 2. NRC Order Number EA-12-051, Issuance of Order to Modify Licenses with Regard to Reliable Spent Fuel Pool Instrumentation, dated March 12, 2012
- 3. USNRC letter to Exelon Generation Company, LLC, Request for Additional Information Regarding Overall Integrated Plan for Reliable Spent Fuel Pool Instrumentation, dated June 26, 2013 In Reference 1, Exelon Generation Company, LLC (EGC) provided the Three Mile Island Nuclear Station, Unit 1, Overall Integrated Plan in Response to the March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Spent Fuel Pool Instrumentation, pursuant to NRC Order No. EA-12-051 (Reference 2).
The purpose of this letter is to provide the response to the NRC request for additional information (Reference 3) regarding the Three Mile Island Nuclear Station, Unit 1 Overall Integrated Plan in Response to the Commission Order Modifying Licenses with Regard to Requirements for Reliable Spent Fuel Pool Instrumentation (Order No. EA-12-051 ).
The Three Mile Island Nuclear Station, Unit 1 Spent Fuel Pool Instrumentation design is proceeding on the schedule identified in the Overall Integrated Plan provided in Reference 1.
The enclosed responses to the NRC request for additional information are intended not to provide preliminary or conceptual information. The requested information, when fully developed, will be provided upon detailed design completion based on the milestone schedule dates provided in each response.
U.S. Nuclear Regulatory Commission Response to Request for Additional Information (Order EA-12-051)
July 24, 2013 Page 2 This letter contains no new regulatory commitments. If you have any questions regarding this response, please contact David P. Helker at 610-765-5525.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 241h day of July 2013.
Respectfully submitted, David P. Helker Manager - Licensing & Regulatory Affairs Exelon Generation Company, LLC
Enclosure:
- 1. Three Mile Island Nuclear Station, Unit 1- Response to Request for Additional Information -
Overall Integrated Plan in Response to Commission Order Modifying License Requirements for Reliable Spent Fuel Pool Instrumentation (Order No. EA-12-051) cc: Director, Office of Nuclear Reactor Regulation NRC Regional Administrator - Region I NRC Senior Resident Inspector- Three Mile Island Nuclear Station, Unit 1 NRC Project Manager, NRR- Three Mile Island Nuclear Station, Unit 1 Mr. Robert J. Fretz, Jr, NRRIJLD/PMB, NRC Mr. Robert L. Dennig, NRRIDSS/SCVB, NRC Mr. Blake Purnell, NRC Project Manager, NRR Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Protection Chairman, Board of County Commissioners of Dauphin County, PA Chairman, Board of Supervisors of Londonderry Township, PA R. R. Janati, Chief, Division of Nuclear Safety, Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection
Enclosure 1 Three Mile Island Nuclear Station, Unit 1 Response to Request for Additional Information Overall Integrated Plan in Response to Commission Order Modifying License Requirements for Reliable Spent Fuel Pool Instrumentation (Order No. EA-12-051)
(11 pages)
Response to Request for Additional Information (Order EA- i 2-051)
Page i of 11
1.0 INTRODUCTION
By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13063A540), Exelon Generation Company, LLC (Exelon, the licensee) 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 requirements for Reliable Spent Fuel Pool (SFP) Instrumentation (Order Number EA-12-051; ADAMS Accession No. ML12054A679) for Three Mile Island Nuclear Station, Unit 1. 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 Spent Fuel Pool Instrumentation,"
Revision 1, dated August 2012 (ADAMS Accession No. ML12240A307), with exceptions, as documented in Interim Staff Guidance (ISG) 2012-03 "Compliance with Order EA-12-051, Reliable Spent Fuel Pool Instrumentation," Revision 0, dated August 29, 2012 (ADAMS Accession No. ML12221A339). Exelon's submittal, dated February 28, 2013, specifies that the 01 P complies with ISG 2012-03.
The NRC staff has reviewed the licensee's submittal dated February 28, 2013, and determined that a response to the following Request for Additional Information (RAI) is needed to complete its technical review. The sections that follow are numbered to coincide with the arrangement presented in NEI 12-02.
2.0 LEVELS OF REQUIRED MONITORING The OIP section regarding identification of SFP Water levels states, in part, that:
Level 1 - Level adequate to support operation of the normal fuel pool cooling system: Indicated level on either primary or backup instrument channel of greater than 21 feet (elevation 340' 4") plus instrument channel 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 is adequate for normal fuel pool cooling system operation. Any elevation above 340' 4" will provide flow of water to fuel pool cooling system.
Level 2 - Level adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck: Indicated level on either the primary or backup instrument channel of greater than 10 feet (elevation 329' 4")
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. 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 3- Level where fuel remains covered: Indicated level on either the primary or backup instrument channel of greater than 0 feet (elevation 319' 4") 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
Response to Request for Additional information (Order EA-12-051)
Page 2 of 11 the primary and backup instrument channels. This monitoring level assures that water is covering the stored fuel seated in the racks.
Please provide the following:
a) For level1, 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 racks. 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, Level2, and Level3 datum points.
Response
a) The TMI-1 Spent Fuel Pool has two Spent Fuel Pool Cooling Pumps that take suction from the pool with the bottom of the suction elbows (which faces downward) at the 340' elevation. Normal Spent Fuel Pool Level is at the 344' 6" and low level at 343' 6".
Presently Level 1 is considered 340' 4"; however, the detailed design will include a calculation to determine adequate water level to maintain normal fuel pool cooling system operation. This information will be available following acceptance of the 100%
design, scheduled in May 2014. The result will be provided in the August 2014, 6-month Integrated Plan update report to the NRC.
b) A sketch is provided as Attachment 1, "TMI-1 Spent Fuel Pool Elevation Sketch."
Instrument probe mounting details in the Spent Fuel Pool area will be provided in accordance with our response to RAI-3.
3.0 INSTRUMENTATION DESIGN FEATURES 3.2 Arrangement The 01 P section regarding Design Features states, in part, that:
The current plan is to install SFP level sensors in the northwest corner of the SFP A and along the south wall of SFP B. These locations provide in excess of 80' of separation between the sensors. 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 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
Response to Request for Additional Information (Order EA-12-051)
Page 3 of 11 cabling for power supplies and indication for each channel will be separated equivalent to that provided tor redundant safety related services.
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 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/display devices in the main control room or alternate accessible location.
Response
The initial concept is to locate the primary and backup level sensors at the opposite ends of the combined pool. The final locations and cable routings are not available at this time.. A detailed design will include sensor locations and cable routing drawings from the Spent Fuel Pool to each channel indicator. The current plan for the design of the SF PI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100% acceptance of the design in May 2014. The requested information wiU be provided in the August 2014, 6-month Integrated Plan update.
3.3 Mounting The OIP section regarding Design Features 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.
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 SFP/FHB 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.
Response to Request for Additional Information (Order EA-i2-051)
Page 4 of 1i
Response
Device total loading and mounting will be performed as part of the detailed design process.
The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100% acceptance of the design in May 2014. The requested information will be provided in the August 2014, 6-month Integrated Plan update.
3.4 Qualification The 01 P section regarding Design Features 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 using commercial quality programs (such as IS0-9001, "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 device 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: ...
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 (BDB) 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
Response to Request for Additional Information (Order EA-12-051)
Page 5 ot 11 loading at the location where the equipment will be mounted. Include a discussion of this seismic reliability demonstration as it applies to: (i) the level sensor mounted in the SFP area, and (ii) 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.
Response
Device qualification and reliability will be performed as part of the detailed design process. The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100% acceptance of the design in May 2014. The requested information will be provided in the August 2014, 6-month Integrated Plan update.
3.5 Independence The 01 P section regarding Design Features 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.
Please provide the following:
a) A description of how the two channels of the proposed level 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) Further information describing the design and installation of 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 independent power sources, physical and spatial separation, independence of signals sent to the location(s) of the readout devices, and the independence of the displays.
Response
Device channel independence evaluation will be performed as part of the detaiied design process. The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TM!-1 is to begin the design phase in October 2013 with design
Response to Request for Additional Information (Order EA-12-051)
Page 6 ot 11 completion and 100% acceptance of the design in May 2014. The requested information will be provided in the August 2014, 6-month Integrated Plan update.
3.6 Power Supplies The 01 P section regarding Design Features states, in part, that:
Each channel will be normally powered from a different 120Vac [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.
Please provide the following:
a) A description of the electrical AC power sources and capaciti.es for the primary and backup channels.
b) 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 BOB event for the minimum duration needed, consistent with the plant mitigation strategies for BOB external events (Order EA-12-049).
Response
Device total power supply configuration will be performed as part of the detailed design process.
The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100% acceptance of the design in May 2014. The requested information will be provided in the August 2014, 6-month Integrated Plan update.
3.7 Accuracy The OIP section regarding Design Features 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 SFP 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
Response to Request for Additional Information (Order EA-12-051)
Page 7 of 11 the specified lower level of each indicating range {levels 1, 2 or 3) without conflicting or ambiguous indications.
Please provide the toilowing:
a) An estimate of the expected instrument channel accuracy performance (e.g., in% of span) under both: (i) normal SFP level conditions (approximately Level 1 or higher), and (ii) at the BOB 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.
Response
Device channel accuracy analysis will be performed as part of the detailed design process.
The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100% acceptance of the design in May 2014. The requested information will be provided in the August 2014, 6-month Integrated Plan update.
3 ..8 Testing The 01 P section regarding Design Features 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.
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.
Response to Request for Additional Information (Order EA- i 2-051)
Page 8 of 11 c} A description of how calibration tests and functional checks will be performed and the frequency at which they will be conducted. Discuss how these surveillances will be incorporated into the plant surveillance program.
d) A description ot 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.
Response
Device testing requirement analysis will be performed as part of the process and procedure development following the design phase. The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100% acceptance of the design in May 2014.
Following the issue of the design, procedures will start being developed with a projected September 2015 completion date. The requested information will be developed early in the process and will be provided in the February 2015, 6-month Integrated Plan update.
3.9 Display The OIP section regarding Design Features 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 high radiation areas or LOCKED HIGH RAD AREA during normal operation.
Please provide the following:
a) The specific location for the primary and backup instrument channel display.
b) If both the primary and backup display locations are not in the main control room, please pmvide justification for prompt accessibility to displays including primary and alternate
Response to Request for Additional Information (Order EA-12-051)
Enclosure 1 Page 9 of 11 route evaluation, habitability at display location(s), continual resource availability tor 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 wiH enable the information from these instruments to be considered "promptly accessible," from a timing perspective. Include consideration of various drain-down scenarios.
Response
Device channel display location will be finalized during the detailed design process. The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100%
acceptance of the design in May 2014. The requested information will be provided in the August 2014, 6-month Integrated Plan update.
4.0 PROGRAM FEATURES 4.2 Procedures The OIP section regarding Program Features 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 the following:
a) A list of the operating (both normal and abnormal response) procedures, calibration/test procedures, maintenance procedures, and inspection procedures that will be developed for use of the SFP instrumentation in a manner that addresses the order requirements.
b) A brief description of the specific technical objectives to be achieved within each procedure. If your plan incorporates the use of portable spent fuel level monitoring components, please include a description of the objectives to be achieved with regard to the storage location and provisions for installation of the portable components when needed.
Response
Device program features analysis will be performed as part of the detailed design process following the design phase. The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100% acceptance of the design in May 2014. Following the issue of the design, procedures will start being developed with a projected September 2015
Response to Request for Additional Information (Order EA- i 2-051)
Enclosure 1 Page 10 of 11 completion date. The requested information wm be developed early in the process and will be provided in the February 2015, 6-month Integrated Plan update.
4.3 Testing and Calibration The OIP section regarding Program Features 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. A Maintenance Procedure (e.g., 1430 series) will be written to direct calibration and repair of the instruments.
Database IISCP (Improved Instrument Setpoint Control Program) will be used to control the calibration and setpoint parameters. The PIMS PM system will be used to direct the calibration frequency of the instruments.
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 the compensatory actions to be taken in the event that one of the instrument channels cannot be restored to functional status within 90 days.
Response
Device testing and calibration requirements analysis will be performed as part of the detailed design process following the design phase. The current plan for the design of the SFPI system based on the current Exelon Nuclear program schedule for TMI-1 is to begin the design phase in October 2013 with design completion and 100% acceptance of the design in May 2014.
Following the issue of the design, procedures will start being developed with a projected September 2015 completion date. The requested information will be developed early in the process and will be provided in the February 2015, 6-month Integrated Plan update.
Response to Request for Additional Information (Order EA-12-051)
Enclosure 1 11 of 11 ATTACHMENT - TMI-l SPENT FUEL POOL ELEVATION SKETCH
...,...NORTH__
63'-0' 33' -0' SF*T*2A I
ELEV. 340' -4' LE \/EL : LOSS OF SF COOLlNG S'JCT!m~
I 25 -11' APPROX.
?':/ -11' A~'IJROX. LEVEL SENSOR LEVEL SENSOR MEASUREMENT RANCE HEASUREI~ENT RANGE ELEV. 329'-)
LEVEL 2 I ELE\1. 321'-0' ELEV. 319'-4' TOP Or fli[L RACK - ELEV. 319'-4' TOP OF FUEL RACK - ELEV. 319'-1' ELE'J. 319'-1"
~LEVEL 3 I
I ELE\1 305'-0" ELEV. 30;5' -0" CAD FILE: FUEL F'OOL.DWG