L-2006-240, 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 Crrctive Actions 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
norrective Actios (cont'd)
Nuclear Division
- 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
nPLore tive cti (c nt')
Nuclear Division
" 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 s
oU -
nnt Nuclear Division
- 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
- Using event tree and failure probabilities, calculate change in core damage frequency 10
ntn ant Conditions Nuclear Division
- 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 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
'ii Ifnt Inditions (cont'd)
Nuclear Division
- SG secondary side water levels average 84 % wide range
- SG atmospheric steam dumps full open
- Equipment required to mitigate loss of RHR in service
- 2nd qualified Unit Supervisor supervising draindown 12
7PP.
CL2se V No OperEtor f 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 RWSTs
- Sufficient time available to restore using both RHRor implement RWST inventory management 15
FPL Nuclear Division Th rmal-h ydraulic Analysis 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 e Factors or Additiona: IRC Consideration Nuclear Division
" Base RHR restoration time on NPSH requirements (9 hr) rather than core boiling (21 min)
- Failure of PORVs to open for feed & bleed does not result in core damage
- 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
OP ornerstone Nuclear Division
" 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