L-2006-240, Presentation Material Pertaining to Regulatory Conference on Turkey Point Preliminary White Finding Held on 10/10/06

Presentation Material Pertaining to Regulatory Conference on Turkey Point Preliminary White Finding Held on 10/10/06

ML062980382
Person / Time
Site:	Turkey Point
Issue date:	10/17/2006
From:	Jones T Florida Power & Light Co
To:	Document Control Desk, NRC/RGN-II
References
EA-06-200, IR-06-015, L-2006-240
Download: ML062980382 (24)

Text

fAttachment 2 Exempt from Public Disclosure in Accordance with 10CFR2.390 FIPL L-2006-240 10CFR50.4 10CFR2.390 ATTN: Document Control Desk OCT47 2006 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Florida Power and Light Company Turkey Point Unit 3 Docket Nos. 50-250 Presentation Material Pertaining to Regulatory Conference On Turkey Point Preliminary White Finding Held October 10, 2006

Reference:

Letter, Mr. C. A. Casto to Mr. J. A. Stall, Turkey Point Nuclear Plant - NRC Integrated Inspection Report 05000250/2006015; EA-06-200, Preliminary White Finding, dated August 24, 2006 On October 10, 2006, a meeting was held between Florida Power and Light Company (FPL) and the Nuclear Regulatory Commission (NRC) in Atlanta, Georgia regarding a Preliminary White Finding discussed in the above referenced letter.

Provided in the attached are copies of the presentation material presented at the October 10, 2006 meeting. Attachment 1 is non-proprietary. Attachment 2 is considered proprietary and contains potentially sensitive security information. FPL requests that Attachment 2 be withheld from disclosure in accordance with 10CFR2.390.

If there are any questions regarding this letter, please contact Jim Connolly at 305-246-6632.

Sincerely Yours, Terry 0. Jones Vice President Turkey Point Nuclear Plant Attachments: 1) Turkey Point Non-Proprietary Presentation Material Regarding Preliminary White Finding 05000250/2006015-01

2) Turkey Point Proprietary Presentation Material Regarding Preliminary White Finding 05000250/2006015-01 cc: NRC Regional Administrator Senior Resident Inspector, USNRC, Turkey Point an FPL Group company

ATTACHMENT 1 Turkey Point Non-Proprietary Presentation Material Regarding Preliminary White Finding 05000250/2006015-01

FPL Nuclear Division ReguLatory Uonference NVRC Region II, Turkey Point Nuclear Plant Turkey Point Nuclear-Plant Unit 3 Loss of Decay Heat Removal Event I

FPL Nuclear Division

• Introductions

• Overview

• Topics of Discussion

- Event description

- Corrective actions

- Thermal-hydraulic analysis of event

- Mitigating actions

- SDP Analysis

• Closing Remarks 2

FPL Nuclear Division

" FPL agrees that it did not comply with requirements of 10 CFR 50.65(a)(4)

• FPL has learned from the loss of decay heat removal event and has taken actions to prevent recurrence

" FPL evaluation concludes that the change in core damage frequency is less than 1.OE-6/yr 3

F=PL Nuclear Division

" Initial conditions

- Unit 3 in Mode 5

- Draindown in progress to support reactor head removal

" Sequence of events

- While restoring power to 3C 480V load center, spurious undervoltage signal sent to 3A load sequencer

- 3A load sequencer de-energized 3A 4kV bus, causing loss of running 3A RHR pump

- 3A EDG re-energized 3A 4kV bus

- 3A load sequencer does not automatically re-start the 3A RHR pump after loss of offsite power

- Operator started 3B RHR pump and terminated the event in approximately 9 minutes 4

FPL ases Nuclear Division

• Insufficient defense in depth to prevent the event

• The outage risk assessment procedure was insufficient e Experience in maneuvering plant was low with significant shutdown maintenance in progress

• Vendor human error in the configuration of auxiliary switch contacts on a 480V load center breaker that went undetected 5

FP Immdiae CrrctiveActions Taken0 Nuclear Division

• Senior managementlteam augmented by fleet after event for additional oversight

• Additional reviews of remaining outage schedule performed

• Additional controls of protected plant and switchyard equipment implemented

• Outage schedule changes subject to more rigorous review and approval process 6

FPL Long Term Corrective k tions Nuclear Division

" Outage risk assessment and control procedure upgraded

- Responsibility for procedure transferred to Operations

- PNSC approval required for procedure changes

- Clearly identifies required protected in-service equipment for higher risk evolutions

- Provides logic ties for risk significant activities

" Use of dedicated and more experienced licensed operators for outage planning and risk assessment (complete) 7

Nuclear Division norrective Actios (cont'd)

• As-left auxiliary switch contact configuration to be verified by Nuclear Receipt Inspection for 4kV &480V breakers (complete)

• Plant procedures for safety-related breakers revised to check auxiliary switch contact configuration on 4kV &

480V breakers (completed for procedures needed for Fall outage breaker work)

• Applicable plant procedure revised to defeat the sequencer during replacement of 480V load center breakers (complete) 8

Nuclear Division nPLore tive cti (c nt')

" Fleet peer reviews of outage schedule (complete)

" Management challenge of outage schedule (prior to Fall

-outage)

• Enhanced operator and staff training on shutdown risk assessment (in-progress, complete prior to Fall outage)

• Outage risk management improvements (perform prior to RCS draindown)

- Pressurizer code safety removed

- At least two Core Exit Thermocouples available (until just prior to detensioning reactor vessel head)

- Containment closure ability confirmed 9

.PL Nuclear Division s oU - nnt

• Thermal-hydraulic simulation to determine effects of loss of RHR scenarios

- Case 1 - No operator actions

- Case 2 - HHSI feed only

- Case 3 - HHSI feed & PORV bleed

• Use results to develop FPL SDP event tree

• Using event tree and failure probabilities, calculate change in core damage frequency 10

Nuclear Division ntn ant Conditions

• 63 hours7.291667e-4 days <br />0.0175 hours <br />1.041667e-4 weeks <br />2.39715e-5 months <br /> 50 minutes after shutdown

- prior to shutdown reactor was at - 50% power for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />

• RCS being drained to support reactor vessel head lift

• RCS level near reactor vessel flange

• RCS temperature ~115 OF

• RCS vented via:

- Reactor vessel head vent line with 0.219" diameter orifice

- Pressurizer vent line 0.742" diameter

• A-RHR in service e B-RHR in standby I1

FPL Ifnt 'ii Inditions (cont'd)

Nuclear Division

• SG secondary side water levels average 84 %wide range

• SG atmospheric steam dumps full open

• Both RWSTs with inventory ~295,000 gal per unit available for HHSI pump use while maintaining NPSH

• Equipment required to mitigate loss of RHR in service

• 2nd qualified Unit Supervisor supervising draindown 12

7PP. CL2se V No OperEtorf 3tion Nuclear Division

Conclusion:

- With no operator action, RHR cooling will be restored simply by starting an RHR pump within approximately 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> after event initiation

- No core damage with RHR pump start anytime during first 9 hrs of event 13

FPL C&se 2 kZ,71 Feeo Only Nuclear Division

Conclusion:

- Able to sustain steady state condition for at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with single RWST

- No core damage for at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />

- Sufficient time available to implement RWST inventory management or SG secondary water makeup 14

NPL Nuclear Division Case 3 HHSI Feed & PORVs Bleed e

Conclusion:

- No core damage for at least 16 hrs using both RWSTs

- Sufficient time available to restore RHRor implement RWST inventory management 15

FPL Nuclear Division Th rmal-hydraulicAnalysis Conclusions

• SG reflux cooling will prevent core damage without operator action for at least 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />

• The minimum time to start a RHR pump is at least 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> (time to boil is overly conservative as the criterion for RHR pump start)

" Feed & bleed prevents core damage regardless of pressurizer PORVs position

• Managing RWST inventory is proceduralized with options to:

- Throttle HHSI flow

- Establish RWST makeup

- Use opposite unit RWST 16

FPL Nuclear Division e Factors or Additiona:IRC Consideration

" Base RHR restoration time on NPSH requirements (9hr) rather than core boiling (21 min)

• Failure of PORVs to open for feed & bleed does not result in core damage

• Late restoration of RHR based on additional time provided by SG reflux cooling and feed & bleed

• Additional RWST inventory management strategies to extend availability of HHSI suction source

- Throttling HHSI pump flow

- Using opposite unit RWST 17

FSPL MM. of &lo 73.ZZAs Nuclear Division

• Based on a more detailed SDP analysis FPL estimated the total CDF increase for this event to be approximately 2.OE-7Iyr

• CDF increase below risk significance threshold of 1.OE-6/yr

• FPL concluded this violation to be GREEN 18

Nuclear Division OP ornerstone

" NRC ROP Cornerstone for this finding should be "Initiating Events"

- ROP "Initiating Events" Cornerstone objective: limit frequency of events that upset plant stability and challenge critical safety functions

" Definitions: NRC Manual Chapter 0308- ROP Basis Document

- Initiating Events- "such events include reactor trips due to turbine trips, loss of feedwater, loss of off-site power..."

- Mitigating Systems- "include those systems associated with safety injection, residual heat removal, and their support systems..."

" Event attributable to the loss of 3A 4kV bus normal electrical power to the running 3A RHR pump, not involving a failure attributable to the RHR System 19

FPLCousions Nuclear Division

" FPL agrees that it did not comply with requirements of 10 CFR 50.65(a)(4)

" Review of SDP analysis shows low safety significance with delta CDF < 1.OE-6/yr

" FPL has taken timely and aggressive corrective actions to prevent recurrence 20

FPL Nuclear Division Regulatory Conference Open Discussion Questions 21

FNPL Nuclear Division Regulatory Conference Final Remarks 22