proposed turkey point units 6 and 7, response to nrc ... › docs › ml1130 › ml11306a138.pdf ·...

0F=PL L-2011-461

10 CFR 52.3

October 31, 2011

U.S. Nuclear Regulatory CommissionAttn: Document Control DeskWashington, D.C. 20555-0001

Re: Florida Power & Light CompanyProposed Turkey Point Units 6 and 7Docket Nos. 52-040 and 52-041Response to NRC Request for Additional Information Letter No. 038(eRAI 5993) Standard Review Plan Section 08.02 - Offsite Power Systems

Reference:

1. NRC Letter to FPL dated September 29, 2011, Request for AdditionalInformation Letter No.038 Related to SRP Section 08.02 - Offsite Power Systemsfor the Turkey Point Nuclear Plant Units 6 and 7 Combined License Application

Florida Power & Light Company (FPL) provides, as attachments to this letter, itsresponses to the Nuclear Regulatory Commission's (NRC) Request for AdditionalInformation (RAI) 08.02.01-1 through 08.02.01-11 provided in Reference 1. Theattachment identifies changes that will be made in a future revision of the Turkey PointUnits 6 and 7 Combined License Application (if applicable).

If you have any questions, or need additional information, please contact me at 561-691-7490.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on October 31, 2011

Sincerely,

William Maher

Senior Licensing Director - New Nuclear Projects

WDM/RFB

Attachment 1: FPL Response to NRC RAI No. 08.02.01-1 (eRAI 5993)Attachment 2: FPL Response to NRC RAI No. 08.02.01-2 (eRAI 5993)Attachment 3: FPL Response to NRC RAI No. 08.02.01-3 (eRAI 5993)Attachment 4: FPL Response to NRC RAI No. 08.02.01-4 (eRAI 5993)Attachment 5: FPL Response to NRC RAI No. 08.02.01-5 (eRAI 5993)Attachment 6: FPL Response to NRC RAI No. 08.02.01-6 (eRAI 5993)

Florida Power & Light Company

700 Universe Boulevard, Juno Beach, FL 33408

-7_PD

Proposed Turkey Point Units 6 and 7Docket Nos. 52-040 and 52-041L-2011-461

Attachment 7: FPL Response to NRC RAI No. 08.02.01-7 (eRAI 5993)Attachment 8: FPL Response to NRC RAI No. 08.02.01-8 (eRAI 5993)Attachment 9:. FPL Response to NRC RAI No. 08.02.01-9 (eRAI 5993)Attachment 10: FPL Response to NRC RAI No. 08.02.01-10 (eRAI 5993)Attachment 11: FPL Response to NRC RAI No. 08.02.01-11 (eRAI 5993)

cc:PTN 6 & 7 Project Manager, AP1000 Projects Branch 1, USNRC DNRL/NRORegional Administrator, Region II, USNRCSenior Resident Inspector, USNRC, Turkey Point Plant 3 & 4

Proposed Turkey Point Units 6 and 7Docket Nos. 52-040 and 52-041FPL Response to NRC RAI No. 08.02.01-1 (eRAI 5993)L-2011-461 Attachment 1 Page 1 of 1

NRC RAI Letter No. PTN-RAI-LTR-038

SRP Section: 08.02- Offsite Power System

Question for Electrical Engineering Branch (EEB)

NRC RAI Number: 08.02.01-1 (eRAI 5993)

FSAR, Revision 2, Section 8.2.1 states that the transmission lines are designed with abasic insulation level (BIL) that will minimize flashovers caused by lightning. Pleaseprovide BIL value with basis.

FPL RESPONSE:

The applicable lightning impulse-withstand voltage (BIL) for transmission lines is definedas the Positive Critical Impulse Flashover Voltage (CFO). The flashover voltages forFPL's standard 230 kV and 500 kV lines are provided in the table below:

Transmission Line CFONominal Voltage

500 kV 2,235 kV

230 kV 1,425 kV

The CFO value for 230 kV lines is based on manufacturer specifications.

The CFO value for 500 kV lines is based on FPL's Laboratory tests performed on 500 kV towerand insulator string configurations.

This response is PLANT SPECIFIC.

References:

None

ASSOCIATED COLA REVISIONS:

None

ASSOCIATED ENCLOSURES:

None



SRP Section: 08.02 - Offsite Power System



FSAR, Revision 2, Subsection 8.2.1.1 states that 500-kV and 230-kV breakers are ratedfor 50 and 63 kilo-amperes respectively. No ratings are provided for the switchyarddisconnect switches and no basis is provided for the specified fault ratings. Therefore,the applicant is requested to indicate why the ratings of circuit breakers and disconnectswitches are adequate for the application. In particular, provide in the FSAR thecalculated available fault current during the worst case scenario and justify theassumptions used in your analysis. Also, confirm that the breaker interrupting ratings,both symmetrical and asymmetrical, are consistent with the available fault.

FPL RESPONSE:

500 kV and 230 kV disconnect switches are included as part of the Turkey Point Units 6& 7 switchyard. These disconnect switches have the same continuous current rating asthe associated circuit breakers.

Steady state power flow simulations were performed to determine the required currentcapability (amperes RMS) of the 500 kV and 230 kV circuit breakers and disconnectswitches in the Turkey Point Units 6 & 7 switchyard. The load currents were calculatedfor all line in conditions (system intact) and line out conditions. The studies determinedthat for all conditions the load current in the 500 kV and 230 kV circuit breakers anddisconnects switches in the switchyard is less than 4000 amperes.

Short circuit simulations were performed to determine the maximum interrupting duty of500 kV and 230 kV circuit breakers in the switchyard. The maximum fault current wascalculated assuming all generating sources in the study area relevant to Turkey PointUnits 6 & 7 were on-line and contributing to the fault. Under the above assumption, themaximum calculated symmetrical (RMS) fault currents are 21.2 kA and 58.1 kA for the500 kV and 230 kV circuit breakers, respectively. The calculation also verified that theX/R Ratio of the calculated symmetrical fault current is less than 17 for both the 500 kVand 230 kV circuit breakers. Therefore, 500 kV circuit breakers with 50 kA rating and230 kV circuit breakers with 63 kA rating have the capability to interrupt the maximumasymmetrical fault.


References:

None



FSAR Chapter 8, Subsection 8.2.1.1 will be revised in a future COLA revision asindicated below:

FSAR subsection 8.2.1.1, first paragraph, last sentence according to the following:

The 500 WV euitchya rd is rated for a continuous current of 4000.A. and a fault duty ratingof 50 kil.ampere. . The 500 kV buses, circuit breakers and disconnect switches arerated for a continuous current of 4000 A and a fault duty rating of 50 kA.

FSAR subsection 8.2.1.1, second paragraph, fourth sentence according to the following:

The 230 WV sWitchyard is rated for a fault duty rating of 63 kiloamperes. The continuouscurrent rating of the main buses and autotransformer circuit breakers is 4000A.. Thecontinuous current rating' of the buses and circuit breakerS in the tie Sections bet~eenthe main buses is 4000A.The 230 kV buses, circuit breakers and disconnectswitches are rated for a continuous current of 4000A and a fault duty rating of 63kA.


None






FSAR, Revision 2, Subsection 8.2.1.1 states that the switchyard includes surgeprotective devices, and grounding and a lightning protection system in accordance withstandard industry practice. FSAR Table 8.1-201 states that RG 1.204 is applicable tooffsite and onsite power systems. Please clarify if surge protective devices, groundingand lightning system will follow the guidelines of RG 1.204 and revise FSAR Subsection8.2.1.1 accordingly.

FPL RESPONSE:

The FSAR Appendix 1AA, Conformance with Regulatory Guides, states that the TurkeyPoint Units 6 & 7 offsite and onsite power systems conform to RG 1.204 Rev.0 with noexceptions. Turkey Point Units 6 & 7 switchyard will comply with the applicable portionsof the standards referenced in RG 1.204 Rev.0

The guidelines of RG 1.204 Rev.0 include multiple IEEE standards. Accordingly, FSARTable 8.1-201 will be revised to remove the note: Implemented via IEEE-665, "IEEEGuide for Generating Station Grounding" (DCD section 8.3, Reference 18) under the'Remarks' column for RG 1.204.


References:

None


FSAR Table 8.1-201 will be revised in a future COLA revision as indicated below:

Remove the note under the 'Remarks' column for RG 1.204 in Table 8.1-201 on page8.1-3 (Section 8.1).

c. RG 1.204 Guidelines for G G 4ppemented viaLightning Protection IEEE 665,of Nuclear Power Gude for- G.n.ratingPlants Stn t..n Grounding


None






FSAR, Revision 2, Subsection 8.2.1.4 states that the transmission switchyard interfaceagreement will specify that grid maintenance and testing activities that could affectoffsite power reliability be closely coordinated with Units 6 and 7. Please indicate theextent to which maintenance and modifications to the switchyard and substation will bereviewed, controlled, and approved through the PTN process.

FPL RESPONSE:

The Transmission Switchyard Interface Agreement between FPL Power Systems andTurkey Point Units 6 & 7 will establish specific points of accountability for providingeffective monitoring and oversight of all grid, switchyard, and plant activities that couldaffect offsite power. It will require that switchyard maintenance and design changes bereviewed prior to implementation.

The Interface. Agreement will clearly state that all switchyard equipment will bemaintained by Transmission and Substation Operations (TSO). PTN and TSOprocedures will be established for maintenance and coordination of activities in theswitchyard. Plant procedures will specify the means for access control, review, andapproval of switchyard activities.

The interface agreements will specify the primary interface accountabilities as thePower Supply system dispatcher and PTN Shift Manager (SM) or Unit Supervisor (US)for maintenance and testing activities, planned outages, and load reductions. Emergentconditions that could affect offsite power reliability are also coordinated between thePower Systems dispatcher and PTN SM/US. These interface accountabilities will alsobe specified in plant procedures. The Station Area Operations (SAO) Supervisor andthe PTN System Engineer for the switchyard are responsible for maintenance activitiesrelated to the switchyard and offsite power equipment.

Site procedures will require the TSO to obtain prior PTN review and approval ofcorporate and plant procedure changes, design changes, tests, or changes in theconduct of other activities that might affect the switchyard and associated transmissionlines and equipment. In the event prior NRC approval for changes or tests is required,the PTN SM/US will so notify TSO that such changes shall not be implemented untilNRC approval has been obtained.


References:

None



None


None






FSAR, Revision 2, Subsection 8.2.1.4 does not provide details regarding testing andinspection of switchyard component. Please provide details in the FSAR regardingtesting and inspection of switchyard component and the frequency at which they will betested/inspected. Also, discuss whether North American Electric Reliability Corporationstandards will be used for switchyard maintenance and testing.

FPL RESPONSE:

The Turkey Point Units 6 and 7 Final Safety Analysis Report (FSAR) Subsection 8.2.1.4will be revised to include additional details regarding testing and inspection ofswitchyard components and to discuss compliance with NERC reliability standardsapplicable to testing and maintenance.


References:

None


FSAR Subsection 8.2.1.4 will be revised in a future COLA revision to add the followingafter the last paragraph of Subsection 8.2.1.4:

For performance of maintenance, testing calibration and inspection, FPL followsits own field test manuals, vendor manuals and drawings, and industry'smaintenance practices to comply with applicable NERC reliability standards. FPLverifies that these test results demonstrate compliance and takes correctiveactions as necessary.

The interconnecting switchyard, as well as other substation facilities, are subjectto multiple levels of inspection and maintenance. They include the following:

* Monthly walk-through and visual inspection.

* Quarterly oil sampling of power transformers. Oil samples are tested fordissolved gas and oil quality.

* Power circuit breakers are inspected and maintained according to thenumber of operations and length of time in service, in accordance with thebreaker manufacturer's recommendations.

• Doble power testing on power transformers.


* Infrared testing on bus and equipment to identify hot spots.

* Relay functional tests.


None

Proposed Turkey Point Units 6 and 7Docket Nos. 52-040 and 52-041FPL Response to NRC RAI No. 08.02.01-6 (eRAI 5993)L-2011-461 Attachment 6 Page 1 of 1NRC RAI Letter No. PTN-RAI-LTR-038




The Turkey Point switchyard (Clear Sky substation) is shared among Units 6 and 7.Accordingly, GDC 5 appears applicable. GDC 5 requires that component parts of theoffsite power system not be shared among units without sufficient justification, therebyensuring that an accident in one unit of a multi-unit facility can be mitigated using anavailable complement of mitigative features, including required ac power, irrespective ofconditions in the other units and without giving rise to conditions unduly adverse tosafety in another unit. RG 1.32 provides acceptable guidance related to the sharing ofstructures, systems, and components of the preferred offsite power system. Discuss inthe FSAR how GDC 5 is met specifically the capacity of transmission lines toadequately support auxiliary loads of one unit during an accident where the other unit isin a safe shutdown condition.

FPL RESPONSE:.

There is no portion of the single required offsite circuit that is required to conform withGDC 5. GDC 5 applies to structures, systems and components important to safety. Forthe AP1000, the single offsite circuit does not perform a safety-related function, asstated in DCD Subsection 8.1.4.

The results of the grid stability analysis for Turkey Point Units 6 & 7 demonstrate thecapacity and capability of the offsite source to power both units during normal,shutdown, startup, and turbine trip conditions. The results of the failure modes andeffects analysis demonstrate the reliability of the offsite source, which minimizes thelikelihood of its failure under normal, abnormal and accident conditions.


References:

None


None


None






FSAR, Revision 2, Section 8.2.2 states that the grid stability study examined thefollowing contingencies: (1) loss of the largest source, (2) loss of most criticaltransmission circuit, (3) loss of the largest load, (4) grid stability following turbine trip,and (5) breaker failure. Additionally, FSAR states that the results of the grid stabilityanalysis study do not indicate a loss of electric power from any remaining supplies as aresult of, or coincident with, the loss of power generated by the nuclear power units orthe loss of power from the transmission network. (1) Provide in the FSAR theassumptions made, results (maximum and minimum voltage, frequency variations, andfrequency decay rate, etc.) and acceptance criteria for worst case. (2) Also, discuss howoften the grid study is performed.

FPL RESPONSE:

The worst case in the grid stability analysis was associated with a 3-Phase fault on thehigh side of Turkey Point 6 main step-up transformers (GSU) simultaneously with afailure of one of the 230kV switchyard circuit breakers for the GSU. In addition to thoseassumptions stated in the FSAR Subsection 8.2.2, the following assumptions are usedin this analysis:

• 242 kV and 514 kV are the voltages at the plant switchyard 230 kV bus and500kV bus respectively

* Grid load at 60% off-Peak load (transient values are worse than 100% load)• Turkey Point Unit 6 auxiliary load of 100MW and 60 Mvars remains connected

after tripping of the unit and generator circuit breaker after 3 cycles.* breaker failure protection operates and isolates the faulted GSU from the grid

The calculated transient values for 230kV switchyard voltage and frequency are:• voltage variation 1.044 pu - 1.09 pu* frequency variation 59.73 Hz - 60.23 Hz• frequency decay < 1 Hz/sec.

The results for all contingency cases showed no instabilities, no relay operations, noload shedding, no voltage violations and no line-loading violations. The lowest value ofsteady state voltage computed in all contingency cases is 228 kV, and the highest valueof steady state voltage computed is 245 kV.

As changes to the grid arise due to load forecasts and changes ingeneration/transmission, the stability of the grid is studied as part of the normaltransmission system assessment to ensure compliance with NERC and FRCC reliabilitystandards and the effectiveness of the transmission plan. To the extent necessary,adjustments to the results of the Turkey Point Units 6 & 7 study may be warranted, and


in such circumstances such adjustments will be communicated in a timely manner to theappropriate departments.


References:

None


None


None

Proposed Turkey Point Units 6 and 7Docket Nos. 52-040 and 52-041FPL Response to NRC RAI No. 08.02.01-8 (eRAI 5993)L-2011-461 Attachment 8 Page 1 of 1NRC RAI Letter No. PTN-RAI-LTR-038




FSAR, Revision 2, Section 8.2.2 states that the results of turbine trip simulationsdemonstrate that the voltage and frequency of 230 kV switchyard buses remain withinthe limits required to maintain reactor coolant pump operation for at least 3 secondsfollowing a turbine trip in either Unit 6 or 7. Provide in the FSAR, a summary of thesimulation results (pre-trip steady-state voltage, voltage at the pump terminals withacceptance criteria.)

FPL RESPONSE:

The steady state pre-trip voltage at the Turkey Point Units 6 and 7 230 kV switchyardused for the turbine trip simulation is 1.045 pu or 240.35 kV.

To ensure adequate voltage is maintained to the reactor coolant pumps for 3 secondsfollowing a turbine trip event, Westinghouse requires that the voltage at the high side ofthe generator step-up transformer (GSU) and reserve auxiliary transformers (RATs) notdrop more than 0.15 pu from the pre-trip steady state voltage. A grid stability analysisfor Turkey Point Units 6 and 7 was performed which shows that during a turbine tripevent, the voltage at the plant 230 kV switchyard does not drop below the pre-tripvoltage. After a turbine trip, the voltage rises and remains above the pre-trip voltagevalue. The steady state voltage after the transient is approximately 242 kV, which is anincrease of approximately 0.007 pu from the pre-trip steady state voltage.


References:

None


FSAR Chapter 8, Subsection 8.2.2 will be revised in a future COLA revision as indicatedbelow:

FSAR subsection 8.2.2, add the following at the beginning of the thirteenth paragraph:

In order to maintain Reactor Coolant Pump (RCP) operation for three secondsfollowing a turbine trip as specified in DCD Subsection 8.2.2, the grid voltage atthe high-side of the GSU, and RATs cannot dip more than 0.15 pu from the pre-trip steady-state voltage.


None






The scope of the interface agreement does not include communication to the gridoperator of risk-sensitive plant maintenance activities that could affect grid conditions.Clarify whether: (a) they coordinate Nuclear Power Plant maintenance activities that canhave an impact on the transmission system with the TSO; and (b) they have contactswith the TSO to determine current and anticipated grid conditions as part of the gridreliability evaluation performed before conducting grid-risk-sensitive maintenanceactivities. Clarify if risk sensitive maintenance activities are shared between the Unitsand if quantitative or qualitative grid reliability evaluation will be performed at PTN Units6 & 7 as part of the maintenance risk assessment required by 1 OCFR 50.65(a)(4) beforeperforming grid-risk-sensitive maintenance.

FPL RESPONSE:

The Interface Agreement and associated communication protocols will be in accordancewith the requirements of NERC Reliability Standard NUC-001.

The Interface Agreement will require a qualitative risk assessment of plant maintenanceand testing activities and will require these activities to be coordinated with TSO toprevent inadvertent reductions in nuclear plant defense-in-depth. PTN will inform thePower Supply system dispatcher of planned outages and planned Load reductions. ThePTN Shift Manager (SM) or Unit Supervisor (US) for maintenance and testing activitieson the affected unit will provide early warning to the Power Supply system dispatcherand the SM and/or US of the unaffected units of potential or developing plant conditionsthat could cause grid instabilities. The detailed interface coordination for plant interfacerequirements and work controls for Turkey Point Units 6 & 7 will be controlled by plantprocedures.


References:

None


None


None






FSAR, Revision 2, Section 8.2.2 states that the transmission study confirmed that theinterface requirements for steady state load, inrush kVA for motors, nominal voltage,allowable voltage regulation, nominal frequency, allowable frequency fluctuation,maximum frequency decay rate, and the limiting under frequency value for the RCPhave been met. Please provide in the FSAR a summary of the grid stability interfaceevaluation results, the assumptions made, and the acceptance criteria for worst caseanalyzed.

FPL RESPONSE:

The Turkey Point Units 6 and 7 Final Safety Analysis Report (FSAR) Section 8.2 will berevised to include a new Table 8.2-201 showing the information being requested.


References:

None


FSAR Chapter 8, Subsection 8.2.2 will be revised in a future COLA revision as indicatedbelow:

The tr i .tudy con.firmd Table 8.2-201 confirms that the interfacerequirements for steady-state load, inrush kVA for motors, nominal voltage, allowablevoltage regulation, nominal frequency, allowable frequency fluctuation, maximumfrequency decay rate, and the limiting under frequency value for the reactor coolantpump have been met.

FSAR Table 8.2-201 will be added to Section 8.2 in a future COLA revision as indicatedbelow:


Table 8.2-201Grid Stability Interface Evaluation

DCD Table 1.8-1 Item 8.2 WEC Offsite ACParameter Requirement PTN 6 & 7 Value Assumed

Steady-state load "normal running values Load in each Unit =provided as input to grid (100 +j 60) MVAstability"

Inrush kVA for motors 56,712 kVA* 56,712 kVA *

Nominal voltage Not provided 230 kV

Allowable voltage regulation 0.95-1.05 pu steady state 0.95-1.05 pu steady state0.15 pu transient dip** 0.15 pu transient dip**

Nominal frequency 60 Hz 60 Hz

Allowable frequency + 112 Hz indefinite + 1/2 Hz indefinitefluctuation

Maximum frequency decay 5 Hzlsec 5 Hz/secrate

*Based on the inrush of a single 10,000 HP feedwater pump assuming efficiency =

0.95, pf = 0.9, and inrush = 6.5 x FLA

** Applicable to Turbine Trip Only. The maximum allowable voltage dip from the pre-event steady state voltage value during the 3-second turbine trip transient event asmeasured at the point of connection to the high side of the generator step-uptransformer and the reserve auxiliary transformer.

DCD Table 1.8-1 Item 8.2 Parameter WEC Offsite AC PTN 6 & 7 Value CalculatedRequirement

Limiting under frequency value for > 57.7 Hz > 59.73 HzRCP


None






Table 1.8-1 of the AP1000 design certification provides an interface item that states "theprotective devices controlling the switchyard breakers are set with consideration givento preserving the plant grid connection following a turbine trip." This is to ensure thatRCP bus voltage stays above the voltage required to maintain the flow assumed in theDCD Tier 2, Chapter 15 analyses for a minimum of 3 seconds following a turbine trip.Provide a reference to where this interface item is discussed in the FSAR.

FPL RESPONSE:

The Turkey Point Units 6 & 7 Final Safety Analysis Report (FSAR) Subsection 8.2.1.2.1will be revised to include the interface item described above.


References:

None


FSAR Subsection 8.2.1.2.1 will be revised in a future COLA revision to add the followingas a new paragraph after the last paragraph of Subsection 8.2.1.2.1:

The protective devices controlling the switchyard breakers are set withconsideration given to preserving the plant grid connection following a turbinetrip.


None

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