ML13157A065
| ML13157A065 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/10/2013 |
| From: | Jennivine Rankin Plant Licensing Branch IV |
| To: | Edington R Arizona Public Service Co |
| Rankin J NRR/DORL/LPL4 | |
| References | |
| EA-12-051, TAC MF0774, TAC MF0775, TAC MF0776 | |
| Download: ML13157A065 (12) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 10, 2013 Mr. Randall K. Edington Executive Vice President Nuclear!
Chief Nuclear Officer Mail Station 7602 Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION, UNITS 1,2, AND 3 REQUEST FOR ADDITIONAL INFORMATION REGARDING OVERALL INTEGRATED PLAN IN RESPONSE TO ORDER EA-12-051, "RELIABLE SPENT FUEL POOL INSTRUMENTATION" (TAC NOS. MF0774, MF0775, AND MF0776)
Dear Mr. Edington:
By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13070A077), Arizona Public Service Company (APS, the licensee),
submitted an Overall Integrated Plan (OIP) in response to the March 12,2012, U.S. Nuclear Regulatory Commission (NRC, Commission) Order modifying licenses with regard to requirements for Reliable Spent Fuel Pool (SFP) Instrumentation (Order EA-12-051; ADAMS Accession No. ML12054A679), for the Palo Verde Nuclear Generating Station, Units 1, 2, and
- 3. The NRC staff endorsed Nuclear Energy Institute (NEI) 12-02, "Industry Guidance for Compliance with U.S. Nuclear Regulatory Commission (NRC) Order EA-12-051, To Modify Licenses with Regard to Reliable SFP Instrumentation," Revision 1, August 2012 (ADAMS Accession No. ML12240A307), with exceptions as documented in Interim Staff Guidance (ISG) 2012-03, "Compliance with Order EA-12-051, Reliable SFP Instrumentation," Revision 0, dated August 29,2012 (ADAMS Accession No. ML12221A339).
The NRC staff has determined that additional information, as requested in the Enclosure, is needed to complete its review. The draft request for additional information (RAI) was sent to Mr. Robert Roehler of APS on June 3, 2013, via e-mail, with a request to respond within 30 days from the date of the e-mail. Mr. Roehler of APS confirmed on June 5, 2013, that an RAI clarification call is not needed and agreed to provide the response by July 3, 2013. If any part of the information is not available by July 3, 2013, please provide the date in which the information will be provided.
R. Edington -2 If you have any questions regarding this request, please contact me at (301) 415-1530 or via e-mail at jennivine.rankin@nrc.gov.
Jennivine K. Rankin, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-529, and STN 50-530
Enclosure:
As stated cc w/encl: Distribution via Listserv
REQUEST FOR ADDITIONAL INFORMATION OVERALL INTEGRATED PLAN IN RESPONSE TO ORDER EA-12-051, "RELIABLE SPENT FUEL POOL INSTRUMENTATION" ARIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION UNITS 1, 2 AND 3 DOCKET NOS. 50-528, 50-529 AND 50-530
1.0 INTRODUCTION
By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13070A077), Arizona Public Service Company (the licensee) submitted an Overall Integrated Plan (OIP) in response to the March 12, 2012, U.S. Nuclear Regulatory Commission (NRC), Commission Order modifying licenses with regard to requirements for Reliable Spent Fuel Pool (SFP) Instrumentation (Order EA-12-051; ADAMS Accession No. ML12054A679) for Palo Verde Nuclear Generating Station Units 1, 2, and 3.
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, August 2012 (ADAMS Accession No. ML12240A307), with exceptions as documented in Interim Staff Guidance (ISG) 2012-03, "Compliance with Order EA-12-051, Reliable SFP Instrumentation," Revision 0, dated August 29,2012 (ADAMS Accession No. ML12221A339).
The NRC staff has reviewed the licensee's letter dated February 28, 2013, 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
- 1. Level adequate to support operation of the normal fuel pool cooling system -Indicated level on either the primary or backup instrument channel of 23 feet 4.5 inches above the top of the fuel storage racks, corrected for the accuracy of the SFP level instrument channel, which is to be determined. This level provides adequate margin to maintain fuel pool cooling system operation.
- 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 (+/- 1 foot) above the top of the fuel storage racks based on Reference 2 and Reference 3. The 10 feet criterion is conservative with regard to dose, in that the Palo Verde UFSAR (Reference 5) sections 9.1.3.3.1.3 and 9.1.4.3.4 indicate that dose would remain at or Enclosure
-2 below 2.5 millirem/hr at the surface of the water. This monitoring level ensures there is adequate water level to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck.
- 3. Level where fuel remains covered - Indicated level on either the primary or backup instrument channel of greater than 1 foot above the top of the fuel storage racks, corrected for the accuracy of the SFP level instrument channel, which is to be determined. This monitoring level assures there is adequate water level above the stored fuel seated in the rack.
RAI-1
Please provide the following:
a} The specific functional reasons for identification of the elevations within the SFP as Levels 1, 2 and 3. For level 1, please 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). Please 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 3.1 Arrangement The OIP states, in part, that The primary system mounting bracket can be located in or near the plant north east corner of the pool, attached on the east deck.
The backup system mounting bracket can be located along the plant east side of the spent fuel pool consistent with the guidelines in Reference 2 and 3.
The detailed location of the primary and backup system mounting brackets, for each of the three SFPs, will be determined during the design phase with consideration of power availability and separation requirements to protect against potential missiles. This is an Open Item described in Section XIX of this document.
-3 The level sensing electronics for both primary and backup systems will be located in the respective auxiliary building, compliant with Reference 2 and Reference 3 for separation and accessibility.
The primary system indicator will be located in the control room. The backup system indicator will be located in an accessible location. The locations will allow for reading of the indicators following an event.
RAI-2
Please provide the following:
a) 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.
b) A plant-specific evaluation of the proposed wireless technology that will be used in the primary and backup measurement systems to address the criteria summarized in Section 3.1 of NEI 12 02.
3.2 Mounting The OIP states, in part, that The mounting of both the primary and backup system will be installed to maintain its integrity during and following a design basis seismic event. The locations will be reviewed for two-over-one seismic interference.
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 and dynamic loads. Please 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. Please indicate in a schematic the portions of the level sensor that will serve as points of attachment for mechanical/mounting or electrical connections.
- 4 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.
3.3 Qualification The OIP states, in part, that Reliability of both instrument channels will be demonstrated via an appropriate combination of design, analyses, operating experience, and/or testing of channel components for the following sets of parameters, as described in the paragraphs below:
(1) conditions in the area of instrument channel component used for each instrument component, (2) effects of shock and vibration on instrument channel components used during and following any applicable event for installed components, and (3) seismic effects on instrument channel components used during and following a potential seismic event for installed components.
The instrument channel reliability will be demonstrated using an appropriate combination of design, analyses, operating experience, and/or testing of channel components for the effects of shock and vibration. Demonstration of shock and vibration adequacy will be consistent with the guidelines in Reference 2 and Reference 3.
Demonstration of seismic adequacy will be achieved using one or more of the following methods:
(1) demonstration of seismic motion consistent with that of existing design basis loads at the installed location; (2) 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; (3) adequacy of seismic design and installation is demonstrated based on the guidance in Sections 7, 8,9, and 10 of [Institute of Electrical and Electronics Engineers (IEEE)] Standard 344-2004, IEEE Recommended Practice for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations, (Reference 7) or a substantially similar industrial standard; (4) demonstration that proposed devices are substantially similar in design to models that have been previously tested for seismic effects in excess of
-5 the plant design basis at the location where the instrument is to be installed (g-Ievels and frequency ranges).
RAI-4
Please provide the following:
a) A description of the specific method or combination of methods the licensee intends 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.
Please 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.
3.4 Independence The OIP states, in part, that The backup instrument system will be redundant to and independent of the primary instrument system.
Independence of the two systems includes: location, mounting, power sources, power and signal wiring, and indications, to prevent any failure of one system from affecting the other system.
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 precluded.
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
- 6 signals sent to the location(s) of the readout devices, and the independence of the displays.
3.5 Power Supplies The OIP states, in part, that An [alternating current (ac)] source will be selected for each system's 24-Vdc
[Volts direct current] UPS [uninterruptible power supply], with power cables routed separately through existing or new tray / conduit and penetrations. Both channels will be powered by independent batteries following a loss-of-ac power.
The minimum battery life will be 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> battery life is a sufficient amount of time for an alternate source of power to be provided by the plant specific procedures to address Reference 6. The alternate power source is provided as part of the NEI 12-06 FLEX equipment (Reference a[l l) and is not provided solely for the SFP instrumentation. Each channel will include an externally accessible bulkhead connector and transfer switch for connection of an alternate 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 (UPS)), please provide the design criteria that will be applied to size the batteries 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 mitigation strategies for beyond design basis external events (Order EA-12-049).
3.6 Accuracy The OIP states, in part, that Instrument channels will be designed such that they will maintain their specified accuracy without recalibration following a power interruption or change in power source.
The accuracy will be within the resolution requirements of Reference 2, Figure 1.
The instrument accuracy will be sufficient to allow personnel using plant procedures to determine when the water level reaches levels 1, 2, and 3 (Section III, Items 1, 2, and 3) without conflicting or ambiguous indication.
Nuclear Energy Institute, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide,"
NE112-06 [Rev. 0], August 2012 (ADAMS Accession No. ML12242A378).
-7
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 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.
3.7 Testing The DIP states, in part, that Instrument channel design will provide for routine testing and calibration consistent with Reference 2 and Reference 3.
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. Please describe how calibration tests will be performed, and the frequency at which they will be conducted. Also, 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.
- 8 3.8 Display The OIP states, in part, that The primary system indicator will be located in the control room. The backup system indicator will be located in an accessible location. The locations will allow for reading of the indicators following an event. The display will provide continuous indication of the SFP water level and will be consistent with the guidelines of References 2 and 3.
RAI-9
Please provide the following:
a) The specific location for the backup instrument channel display.
b} If the backup display location is other than the main control room, then 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 4.1 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 new SFP instrumentation.
FLEX Support Guidelines will address a strategy to ensure the SFP water makeup is initiated at an appropriate time consistent with implementation of NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide (Reference 8).
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.
- 9 4.2 Testing and Calibration The alP 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 other documented bases, consistent with Reference 2, Section 4.3.
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. Please 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.
ML13157A065 *memo dated 5/17/13 OFFICE NRRlDORULPL4/PM NRRlDORULPL4/LA NRRlDSS/SBPB/BC NRRlDORULPL4/BC NRRlDORULPL4/PM NAME JRankin JBurkhardt GCasto* MMarkley KKalyanam for JRankin DATE 6/10/13 617113 5/17113 6/10/13 6/10/13