ML13156A313

Request for Additional Information, Overall Integrated Plan in Response to 3/12/12 Commission Order Modifying Licenses with Regard to Reliable Spent Fuel Pool Instrumentation (Order EA-12-051)

ML13156A313
Person / Time
Site:	Arkansas Nuclear
Issue date:	06/26/2013
From:	Kalyanam N Plant Licensing Branch IV
To:	Entergy Operations
Kalyanam N
References
EA-12-051, TAC MF0944, TAC MF0945
Download: ML13156A313 (12)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 June 26, 2013 Vice President, Operations Arkansas Nuclear One Entergy Operations, Inc.

1448 S.R 333 Russellville, AR 72802

SUBJECT:

ARKANSAS NUCLEAR ONE, UNITS 1 AND 2- REQUEST FOR ADDITIONAL INFORMATION REGARDING OVERALL INTEGRATED PLAN FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION (ORDER NO. EA-12-051) (TAC NOS. MF0944 AND MF0945)

Dear Sir or Madam.

By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13063A015), Entergy Operations, Inc. (Entergy), submitted an Overall Integrated Plan 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) lnstrumentalion (Order EA-12-051; ADAMS Accession No. ML12054A679) for Arkansas Nuclear One, Units 1 and 2.

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 transmitted to Entergy via e-mail on May 7, 2013. Ms. N. Mosher of your offices confirmed that an RAI clarification call is needed which took place on June 6, 2013. Your response is requested no later than 30 days from the date of this Jetter.

If you have any questions, please contact me at 301-415-1480 or via e-mail at kaly.kalyanam@nrc.gov.

Sincerely, N. Kaly Kalyanam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-313 and 50-368

Enclosure:

As stated cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION OVERALL INTEGRATED PLAN IN RESPONSE TO THE COMMISION ORDER MODIFYING LICENSES WITH REGARD TO REQUIREMENTS FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION (ORDER EA-12-051)

ENTERGY OPERATIONS INC.

ARKANSAS NUCLEAR STATION ONE UNITS 1 AND 2 DOCKET NOS. 50-313 AND 50-368 1.0. INTRODUCTION By letter dated February 28, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13063A015), Entergy Operations, Inc. (Entergy, 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 Arkansas Nuclear One (ANO), 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, 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 February 28, 2013, response by the licensee and determined that the following request for additional information (RAJ) is needed to complete its technical review. If any part of this information is not available within the 60-day response period for this RAJ, please provide the date this information will be submitted.

2.0 LEVELS OF REQUIRED MONITORING The OIP states, in part, that Level 1 is the level adequate to support operation of the normal fuel pool cooling system. It is the higher of the following two points:

(1) The level at which reliable suction loss occurs due to uncovering the coolant inlet pipe or any weirs or vacuum breakers associated with suction loss. This level, (1 ), is established for Unit 1 based on nominal coolant inlet pipe elevation [as it does not incorporate a vacuum (or siphon breaker)] and is established for Unit 2 based on nominal vacuum (or siphon) breaker elevation. The elevation associated with this level is Enclosure

397 feet 5.21 inches for Unit 1 [ ... ]. The elevation associated with this level is 401 feet 0 inches for Unit 2 [ ... ].

(2) The level at which the normal fuel pool cooling pumps lose required NPSH [net positive suction head] assuming saturated conditions in the pool. It can be demonstrated that this elevation is below the elevation that defines Level 1 per (1) above. Unit 1 SFP Cooling pumps are at elevation 337'-0" with a required NPSH of 14FT for suction temperatures up to 200 [degrees Fahrenheit ('F)). Unit 2 SFP Cooling pumps are at elevation 336'-2.5" with a required NPSH of 20FT for suction temperatures up to 200°F.

The higher of the above points is (1). Therefore, LEVEL 1 is elevation 397 feet 5.21 inches for Unit 1 and LEVEL 1 is elevation 401 feet 0 inches for Unit 2.

Level 2 is the level adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck. Level 2 may be based on either of the following:

(1) 10 feet+/- 1 foot above the highest point of any fuel rack seated in the spent fuel pool. The elevation associated with this level is 385 feet 11.5675 inches +/- 1 foot for Unit 1. The elevation associated with this level is 388 feet 3.3125 inches+/- 1 foot for Unit 2.

(2) A designated level that provides adequate radiation shielding to maintain personnel dose within acceptable limits while performing local operations in the vicinity of the pool. This level is based on plant*specific or appropriate generic shielding calculations. The elevation associated with this level is not calculated since item (1) is used to establish Level2.

In lieu of plant specific dose calculations required by (2), (1) is used as the conservative accepted level as suggested by NEI 12-02 Revision 1. Therefore, LEVEL 2 is elevation 385 feet 11.5675 inches+/- 1 foot for Unit 1 and LEVEL 2 is elevation 388 feet 3.3125 inches+/- 1 foot for Unit 2 (i.e. 10 +/- 1 feet above Top of Fuel Rack).

Level 3 is the level where fuel remains covered. It is defined as the highest point of any fuel rack seated in the spent fuel pool (within+/- 1 foot).

The highest point (nominal) of any fuel rack seated in the spent fuel pool is 375 feet 11.5675 inches for Unit 1 [ ... )and 378 feet 3.3125 inches for Unit 2 [ ... ].

Therefore, LEVEL 3 is elevation 375 feet 11.5675 inches+/- 1 foot for Unit 1 and LEVEL 3 is elevation 378 feet 3.3125 inches+/- 1 foot for Unit 2.

The SFP level instrument span will extend down to at least 3 inches below the upper limit of the range of LEVEL 3 to account for channel accuracy or instrument loop uncertainty. Therefore, the SFP level probe will extend down to

at least elevation 376 feet 8.5675 inches for Unit 1 and 379 feet 0.3125 inches for Unit 2.

RAI-1

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. 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 Mounting The OIP states, in part, that Both the primary and backup system installation will incorporate seismic category I mounting to meet the NRC JLD-ISG-2012-03 and NEI 12-02 guidance requirements. Other hardware stored in the SFP will be evaluated to ensure that it does not adversely interact with the SFP instrument probes during a seismic event.

RAI-2

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. 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.

(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.

3.2 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 will be supplied by manufacturers that implement commercial quality programs (such as 1809001, 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 a history of operational reliability in environments with significant shock and vibration loading, 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 replaceable batteries and chargers), the following measures will be used to verify that the design and installation is adequate:

• Components will be 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:

o demonstration of seismic motion will be consistent with that of existing design basis loads at the installed location; o 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 will be inclusive of the effects of seismic motion imparted to the components proposed at the location of the proposed installation; o demonstration of seismic reliability using methods that predict equipment performance (e.g., analysis, testing, combination thereof, or use of experience data) where demonstration should be based on the guidance in Sections 7, 8, 9, and 10 of Reference 5 or a substantially similar industrial standard; o 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-levels and frequency ranges);

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

RAI-3

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 (BOB) 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 following seismic conditions to maintain its required accuracy.

3.3 Independence The OIP states, in part, that The primary instrument channel will be independent of the backup instrument channel. Independence is obtained by physical separation of components between channels and the use of normal power supplied from separate 480 [Volt (V)] buses. Independence of power sources is described in Section 11. The two (2) permanently mounted instruments in the pool are physically separated as described in Sections 6 and 7.

RAI-4

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 signals sent to the location(s) of the readout devices, and the independence of the displays.

3.4 Power Supplies The OIP states, in part, that The power supplies for the instrument channels are shown on Attachment 3 and arranged as follows:

Each instrument channel is normally powered from 120 [Volts alternating current (VAC)]60 ]Hertz (Hz)] plant power to support continuous monitoring of SFP level. The primary channel receives power from a different 480V bus than the backup channel. Therefore, loss of any one 480V bus does not result in loss of normal 120VAC power for both instrument channels.

• On loss of normai120VAC power, each channel's [uninterruptible power supply (UPS)] automatically transfers to a dedicated backup battery. If normal power is restored, the channel will automatically transfers back to the normal AC power.

• The backup batteries are maintained in a charged state by commercial-grade uninterruptible power supplies. The batteries are sized to be capable of supporting intermittent monitoring for a minimum of 3 days of operation. This provides adequate time to allow the batteries to be replaced, or until off-site resources can be deployed by the mitigating strategies resulting from Order EA-12-049 Revision 0.

• An external connection permits powering the system from any portable [direct current (DC)] source.

• Instrument accuracy and performance are not affected by restoration of power or restarting the processor.

RAI-5

Please provide the following:

a) The sample rate under intermittent monitoring conditions and explain if the sample rate is determined by the instrument, or by plant procedures.

b) 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 FLEX Program plans.

3.5 Accuracy The OIP states, in part, that Accuracy will be consistent with the guidelines of NRC JLD-ISG-2012-03 Revision 0 and NEI12-02 Revision 1. Accuracy and indication features are as follows:

• Accuracy: The absolute system accuracy is equal or better than +/-

3 inches. This accuracy is applicable for normal conditions and the temperature, humidity, chemistry, and radiation levels expected for BDBE

[beyond design basis event] event conditions.

• Trending: The display trends and retains data when powered from either normal or backup power.

• Restoration after Loss of Power: The system automatically swaps to available power (backup battery power or external DC source) when normal power is lost. Neither the source of power nor system restoration impact accuracy. Previously collected data is retained.

• Diagnostics: The system performs and displays the results of real-time information related to the integrity of the cable, probe, and instrument channel.

The above features ensure that trained personnel can easily determine when SFP level falls below each regulatory level (levels 1, 2 and 3) without conflicting or ambiguous indication.

RAI-6

Provide responses to the following:

a) An estimate of the expected instrument channel accuracy performance (e.g., in percentage of calibrated span) under both a) normal SFP level conditions (approximately Level1 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 Level2 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.

3.6 Testing OIP states, in part, that Testing and calibration will be consistent with the guidelines of NRC JLD-ISG-2012- 03 Revision 0 and NEI 12-02 Revision 1 and vendor recommendations.

The display/processor performs automatic in~situ calibration and automatically monitors for cable, connector, and probe faults using Time Domain Reflectometry (TOR) Technology. Channel degradation due to age or corrosion is not expected but associated testing, calibration, and monitoring provides reasonable opportunity for identification thereof.

Station procedures and preventive maintenance tasks will be developed as necessary (e.g. to perform required surveillance testing, calibration, backup battery maintenance, functional checks, and visual inspections of the probes).

RAI-7

Please provide the following:

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

4.0 PROGRAM FEATURES 4.1 Procedures The OIP states, in part, that Procedures for maintenance and testing will be developed using regulatory guidelines and vendor instructions.

BDBE event operations guidance will also address the following:

• A strategy to ensure SFP water addition is initiated at an appropriate time consistent with implementation of NEI 12-06 Revision 1.

• Restoration of non-functioning SFP level channels after an event.

Restoration timing will be consistent with the emergency condition. After an event, commercially available components that may not meet all qualifications may be used to replace components to restore functionality.

RAI-8

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.

4.2 Testing and Calibration The OIP states, in part, that Station procedures and preventive maintenance tasks will be developed as necessary (e.g. to perform required surveillance testing, calibration, backup battery maintenance, functional checks, and visual inspections of the probes).

Testing and calibration processes will be developed consistent with the guidelines of NRC JLD-ISG-2012-03 Revision 0, NEI12-02 Revision 1, and vendor instructions.

RAI-9

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.

ML12054A679) for Arkansas Nuclear One, Units 1 and 2.

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 (RAJ) was transmitted to Entergy via e-mail on May 7, 2013. Ms. N. Mosher of your offices confirmed that an RAJ clarification caJJ is needed which took place on June 6, 2013. Your response is requested no later than 30 days from the date of this letter.

If you have any questions, please contact me at 301-415-1480 or via e-mail at kaly.kalyanam@nrc.gov.

Sincerely, IRA/

N. Kaly Kalyanam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-313 and 50-368

Enclosure:

As stated cc w/encl: Distribution via Listserv DISTRIBUTION:

PUBLIC RidsNrrDoriLpl4 Resource CRoque-Cruz, NRR/DSS/SBPB LPLIV Reading RidsNrrLAJBurkhardt Resource SDarbali, NRRIDE/EICB RidsAcrsAcnw_MaiiCTR Resource RidsNrrPMANO Resource RidsNrrDoriDpr RidsRgn4MaiiCenter Resource ADAMS Accession No. ML13156A313 *See memo dated April30, 2013 OFFICE NRR/DORULPL4/PM NRR/DORULPL4/LA NRR/DSS/SBPB/BC

• NRR/DORULPL4/BC NRR/DORULPL4/PM MMarkley NAME NKalyanam JBurkhardt GCasto (Flyon for) NKalyanam DATE 6124/13 6/21113 4/30/13 6126/13 6/26/13