NG-13-0389, Response to Request for Additional Information Regarding Overall Integrated Plan in Response to Order EA-12-051
| ML13284A122 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 10/10/2013 |
| From: | Richard Anderson NextEra Energy Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EA-12-051, NG-13-0389 | |
| Download: ML13284A122 (14) | |
Text
INEXTera" EN ERG-2YO
ýýýARNOLD NG-1 3-0389 10 CFR 2.202 October 10, 2013 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Duane Arnold Energy Center Docket No. 50-331 Renewed Op. License No. DPR-49 Response To Request For Additional Information Regarding Overall Integrated Plan In Response To Order EA-12-051
References:
- 1) Order EA-12-051, "Order to Modify Licenses with Regard to Reliable Spent Fuel Pool Instrumentation" dated March 12, 2012 (ML12054A682)
- 2) Letter, R. Anderson (NextEra Energy Duane Arnold, LLC) to U. S. NRC, "NextEra Energy Duane Arnold, LLC's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051)," NG-13-0086, dated February 28, 2013 (ML13063A014)
- 3) Letter, NRC to R. Anderson (Nextera Energy Duane Arnold, LLC,) Request For Additional Information Regarding Overall Integrated Plan For Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051), dated September 16, 2013 On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1, an immediately effective Order to all licensees including NextEra Energy Duane Arnold, LLC (hereafter NextEra Energy Duane Arnold). In Reference 2, NextEra Energy Duane Arnold submitted an Overall Integrated Plan for the implementation of this Order. After review of Reference 2, the NRC Staff has determined that additional information, as requested in Reference 3, is needed to complete its Technical Review. The enclosure to this letter provides the requested information, or the date when additional information will be submitted.
If you have any questions or require additional information contact Ken Putnam at 319-851-7238.
NextEra Energy Duane Arnold, LLC, 3277 DAEC Road, Palo, IA 52324
Document Control Desk NG-1 3-0389 Page 2 of 2 This letter makes no new commitments or changes to existing commitments.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on October 10, 2013 TRicadLAnrs Vice President, Duane Arnold Energy Center NextEra Energy Duane Arnold, LLC Enclosure cc:
Regional Administrator, USNRC, Region III Resident Inspector, USNRC, Duane Arnold Energy Center Project Manager, USNRC, Duane Arnold Energy Center
Attachment to NG-13-0389 NextEra Energy Duane Arnold, LLC's Response To Reguest For Additional Information Regarding Overall Integrated Plan In Response To Order EA-12-051 11 pages follow
Enclosure to NG-13-0389 Page 1 of 11
RAI-1
The OIP states, in part, that:
Level 1: Level adequate to support operation of the normal fuel pool cooling system -
Elevation (853'-8") based on the normal water level in the Spent Fuel Pool. This water level is above the SFP weir wall elevation that is needed to ensure adequate SFP cooling flow.
Level 2: Level adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck - (Elevation 841'-5"). This elevation is approximately 10' above the top of the fuel racks. This monitoring level ensures there is adequate water level to provide substantial radiation shielding for personnel to respond to Beyond-Design-Basis External Events and to initiate SFP makeup strategies.
Level 3: Level where fuel remains covered - (Elevation 831'-5"). This level is the nominal level of the highest fuel rack.
NRC Request Please provide 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, Level 2, and Level 3 datum points.
Enclosure to NG-13-0389 Page 2 of 11 DAEC Response RAI-1 The following sketch contains the information requested in RAI-1. Instrument uncertainty, which is yet to be determined, is not included in the elevation values for Levels 1 and 3.
NOMINAL TOP OF MEASUREMENT RANGE (VALUE ABOVE NORMAL WILL BE ESTABLISHEO IN DETAILEO OESION PHASEI SENSOR ACTIVE MEASUREMENT RANGE BOTTOM OF MEASUREMENT RANGE (APPROXIMATELY 6" BELOW LEVEL 3)
"TO ELECTRONICS SEISMIC I. MOUNTING BRACKET OPERATING OECK = 855"-0' NOFIMAL WATEF LEVEL = 854-0 LEVEL I = 853'-6" LEVEL 2 = 84-1'-5" iý -
LEVEL 3 (TOP OF FUEL RACK) = 831'-5"
Enclosure to NG-13-0389 Page 3 of 11
RAI-2
The OIP states, in part, that:
The two SFP level instrument channels will be installed in diverse locations, arranged in a manner that provides reasonable protection of the level indication function against missiles that may result from damage to the structure over the SFP.
Primary and Backup instrument channel level sensing components will be located in the north side of the SFP. The distance between the Primary and Backup instrument level sensing components will be approximately 20 feet. See Plan View of SFP Showing New SFP Level Instrumentation in Section XVIII, Drawings.
SFP level sensors will be installed in the north side of the SFP. Sensor conditioning electronics and battery backup will be located in the Control Building which is a Class 1 structure that provides protection from all external natural events.
Cabling for power supplies and indications for each channel will be routed in separate conduits from the cabling for the adjacent channel. New components and associated raceway will be installed per Duane Arnold Energy Center (DAEC) specifications and procedures.
NRC Request Please modify the marked-up plant drawing of the plan view (in Section XVIII, Page 10 of 10) of the SFP area, to depict 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.
DAEC Response RAI-2 The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
RAI-3
The OIP states, in part, that:
Mounting will be Seismic Class I. Installed equipment will be seismically qualified to withstand the maximum seismic ground motion considered in the design of the plant area in which it is installed.
Enclosure to NG-13-0389 Page 4 of 11 NRC Request Please provide the following:
c) 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.
DAEC Response RAI-3a, 3b and 3c The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
RAI-4
The OIP states, in part, that:
Instrument channel reliability will be demonstrated via an appropriate combination design, analyses, operating experience, and/or testing of channel components for the following sets of parameters:
Conditions in the area of instrument channel components use for all instrument components
" Effects of shock and vibration on all instrument channel components, and
" Seismic effects on instrument channel components during and following a potential seismic event for all installed components
Enclosure to NG-13-0389 Page 5 of 11 NRC Request 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 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.
DAEC Response RAI-4a, 4b and 4c The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
RAI-5
The OIP states, in part, that:
The primary instrument channel will be redundant to and independent of the backup instrument channel. Independence will be obtained through separation of the sensors, indication, backup battery power supplies, associated cabling and channel feeds.
Cabling for power supplies and indications for each channel will be routed in separate conduits from the cabling for the adjacent channel. New components and associated raceway will be installed per DAEC specifications and procedures.
NRC Request Please provide the following:
Enclosure to NG-13-0389 Page 6 of 11 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.
DAEC Response RAI-5a and 5b The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
RAI-6
The OIP states, in part, that:
Both channels will be powered from dedicated batteries and local battery chargers. The battery chargers for both channels will normally be powered from separate sources of 120V AC power. Minimum battery life of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> will be provided. The battery systems will include provision for battery replacement should the battery charger be unavailable following the event. Spare batteries will be readily available. In the event of a loss of normal power, the battery chargers will be connected to a backup power source.
NRC Request Please provide the following:
a) A description of the electrical AC power sources and capacities for the primary and backup channels, demonstrating that these sources are independent and that the restoration of power to them may be performed independently.
b) Provide the design criteria that will be applied to size the battery in a manner that ensures, with margin, that the channel will be available to run reliably and continuously following the onset of the BDB event for the minimum duration needed, consistent with the plant mitigation strategies for BDB external events (Order EA 049).
Enclosure to NG-13-0389 Page 7 of 11 DAEC Response RAI-6a and 6b The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
RAI-7
The OIP states, in part, that:
Instrument channels will be designed such that they will maintain their design accuracy following a power interruption or change in power source without recalibration. Accuracy will consider Spent Fuel Pool water conditions. Additionally, instrument 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 and 3) without conflicting or ambiguous indication. The accuracy will be within the resolution requirements of Figure 1 of NEI 12-02.
NRC Request Please provide the following:
a) An estimate of the expected instrument channel accuracy performance (e.g., in % of span) under both a) normal SFP level conditions (approximately Level 1 or higher) and b) at the BDB 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.
DAEC Response RAI-7a and 7b The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
Enclosure to NG-13-0389 Page 8 of 11
RAI-8
The OIP states, in part, that:
Instrument channel design will provide for routine testing and calibration consistent with Order EA-12-051 and the guidance in NEI 12-02. Details will be determined during the engineering and design phase. Instrument channel testing and calibration will be performed using existing plant work control processes.
NRC Request 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 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 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.
DAEC Response RAI-8a, 8b, 8c and 8d The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
RAI-9
The OIP states, in part, that:
The design will include remote indication that will be accessible during and after post event conditions. The location will ensure that it meets the following criteria:
promptly accessible to the appropriate plant staff giving appropriate consideration to various drain down scenarios,
Enclosure to NG-13-0389 Page 9 of 11
" outside of the area surrounding the SFP floor, e.g., an appropriate distance from the radiological sources resulting from an event impacting the SFP, inside a structure providing protection against adverse weather, and
" outside of any very high radiation areas or LOCKED HIGH RAD AREA during normal operation.
NRC Request Please provide the following:
a) The specific location for the primary and backup instrument channel displays.
b) For display locations that are not within the main control room, provide a description of the display location that addresses primary and alternate access route evaluation, continuous habitability at display location(s), continual resource availability for personnel responsible to promptly read displays, and provisions for verbal communications with decision makers for the various SFP drain down scenarios and external events.
c) The reasons justifying why the locations selected will enable the information from these instruments to be considered "promptly accessible". Include consideration of various drain-down scenarios.
DAEC Response RAI-9a, 9b and 9c The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
RAI-10
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 new SFP instrumentation.
NRC Request Please provide the following:
Enclosure to NG-13-0389 Page 10 of 11 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.
DAEC Response RAI-10a and 10b The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.
RAI-1l The OIP states, in part, that:
Processes will be established and maintained for scheduling and implementing necessary testing and calibration of the primary and backup spent fuel pool level instrument channels to maintain the instrument channels at the design accuracy.
Testing and calibration of the instrumentation will be consistent with vendor recommendations and any other documented basis. Calibration will be specific to the mounted instrument and the monitor.
NRC Request 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.
Enclosure to NG-13-0389 Page 11 of 11 DAEC Response RAI-11a, 11b and 11c The answer to this request requires design information that is under development. The information will be provided in a six (6) month update after it has been obtained, no later than August 2015.