IR 05000348/2011012
| ML111960460 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 07/15/2011 |
| From: | Scott Shaeffer NRC/RGN-II/DRP/RPB2 |
| To: | Stinson L Southern Nuclear Operating Co |
| References | |
| IR-11-012 | |
| Download: ML111960460 (46) | |
Text
July 15, 2011
SUBJECT:
PUBLIC MEETING SUMMARY - JOSEPH M. FARLEY NUCLEAR PLANT -
DOCKET NOS. 50-348 AND 50-364
Dear Mr. Stinson:
This refers to the Regulatory Conference conducted on July 12, 2011, in Atlanta, GA. The purpose of the Regulatory Conference was to provide opportunities to discuss the safety significance of the preliminary White finding associated with one Apparent Violation that was documented in NRC Inspection Report 05000348/2011012 and 364/2011012 (ML111590912).
The findings dealt with the failure to maintain the configuration of the 1A reactor coolant pump (RCP) oil lift pump system in accordance with plant design and drawings. This resulted in an electrical short on November 10, 2010 that caused a fire on the Unit 1 main control room (MCR)
1A RCP board handswitch. This conference also addressed whether enforcement action is warranted for the associated Apparent Violation.
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter will be available electronically for public inspection in the NRC Public Document Room (PDR) or from the Publicly Available Records (PARS) component of NRCs document system (ADAMS).
ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Should you have any questions concerning this meeting, please contact me at (404) 997-4521.
Sincerely,
/RA/
Scott M. Shaeffer, Chief
Reactor Projects Branch 2 Division of Reactor Projects
Docket Nos.: 50-348, 50-364 License Nos.: NPF-2, NPF-8
Enclosures:
1. List of Attendees
2. NRC Agenda
3. SNC Powerpoint Presentation
REGION II==
245 PEACHTREE CENTER AVENUE NE, SUITE 1200 ATLANTA, GEORGIA 30303-1257
Enclosure 1 FARLEY REGULATORY CONFERENCE Atlanta, GA July 12, 2011
Name (Print)
_____________J. Munday_____________
_____________R. Nease ______________
_____________G. McCoy______________
_____________L. Suggs ______________
_____________R. Fanner______________
_____________G. Wiseman____________
_____________D. Chung______________
_____________E. Crowe______________
_____________W. Rogers_____________
_____________W. Jones______________
_____________R. Croteau_____________
_____________L. Wert________________
_____________S. Sparks______________
_____________S. Shaeffer____________
_____________S. Rose_______________
_____________T. Lighty______________
Title and Organization
Division Director NRC RII/DRS
_Branch Chief NRC RII/DRS/EB2_______
_Branch Chief NRC RII/DRP/RPB5______
_Inspector NRC RII/DRS/EB2__________
_Inspector NRC RII/DRS/EB2__________
_Senior Inspector NRC RII/DRS/EB2____
NRC NRR/DRA/PRA Operational Support
_Senior Resident Farley NRC RII/DRP___
_SRA NRC RII/DRP/RPB7_____________
_Deputy Division Director NRC RII/DRP_
_Division Director NRC RII/DRP _______
Deputy Regional Administrator NRC RII_
Senior Enforcement Specialist NRC RII__
_Branch Chief NRC RII/DRP/RPB2______
Sr. Project Engineer NRC RII/DRP/RPB2
_Project Engineer NRC RII/DRP/RPB2__
UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
245 PEACHTREE CENTER AVENUE NE, SUITE 1200 ATLANTA, GEORGIA 30303-1257
Enclosure 1 FARLEY REGULATORY CONFERENCE Atlanta, GA July 12, 2011 (Via Teleconference)
Name (Print)
_____________M. Ashley___________________
_____________S. Meng Wong_______________
_____________A. Klein_____________________
_____________S. Lee______________________
_____________J. Hyslop___________________
_____________N. Coleman_________________
_____________J. Circle____________________
_____________R. Gallucci__________________
_____________B. Martin___________________
_____________D. Harrison_________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
Title and Organization
NRC HQ/NRR
_NRC HQ/DRA____________________________
_NRC HQ/DRA/AFPB______________________
_NRC HQ/DRA____________________________
_NRC HQ/DRA/FRB_______________________
_NRC HQ/OE_____________________________
_NRC HQ/NRR/DRA/APOB_________________
_NRC HQ/NRR/DRA/APLA__________________
_NRC HQ/NRR/DORL______________________
_NRC HQ/DRA____________________________
_________________________________________
_________________________________________
_________________________________________
_________________________________________
_________________________________________
_________________________________________
Enclosure 1
Enclosure 2
Enclosure 2
REGULATORY CONFERENCE AGENDA SOUTHERN NUCLEAR OPERATING COMPANY JULY 12, 2011 NRC REGION II, ATLANTA, GEORGIA I.
OPENING REMARKS AND INTRODUCTION II. NRC REGULATORY AND ENFORCEMENT POLICY III. STATEMENT OF ISSUE AND APPARENT VIOLATION IV. SOUTHERN NUCLEAR OPERATING COMPANY V. TRANSITION TO CLOSED SESSION (If Required)
a. PUBLIC QUESTIONS b. NRC REMARKS/BREAK c. SOUTHERN NUCLEAR OPERATING COMPANY VI. BREAK/NRC CAUCUS VII. NRC FOLLOW UP QUESTIONS VIII. CLOSING REMARKS IX. PUBLIC QUESTIONS (If Not Previously Performed)
Enclosure 3 Farley Nuclear Plant NRC Regulatory Conference July 12, 2011 Mark J Ajluni, PE Nuclear Licensing Director John D Lattner, PE Principal Engineer - Fire Protection Ken McElroy RIE Program Manager
Enclosure 3
Agenda
- Introductions
- Objectives
- Presentation
- Wrap-Up and Conclusion
Enclosure 3
Objectives 1. To provide new information about the event 2. To prove the handswitch fire that occurred on Nov. 10, 2010, in the Unit 1 control room was a non-challenging fire per the guidance of NUREG/CR 6850 3. To demonstrate that the event is not risk significant and should be characterized as green
Enclosure 3
The Event
- Calibration of 1A RCP oil lift system
- Broken conduit found
- Operators later attempted start of the 1A RCP and detected burning inside the handswitch
- Operator responded by opening panel and blowing on the switch box enclosure
- At the same time the circuit opened and the burning stopped
Enclosure 3
Enclosure 3
Handswitch Internals Spade Terminals Spade Terminal Region Contacts Normally Open
Enclosure 3
Handswitch in Closed Position Contacts Closed
Enclosure 3
Handswitch Spring Returns to Open Arcing
Enclosure 3
Handswitch Damage
Enclosure 3
Testing Results Because we are dealing with a specific wiring arrangement and switch all seven SNC tests of handswitch fault indicate the same location for damage and the repeatable nature of failure for this particular fault.
Enclosure 3
Handswitch Construction
- Fire resistive construction of switch block
- Does not melt or drip plastic
- Fire resistive construction of switch housing
- Objective of testing was to confirm how the switch responds to shorted conditions
Enclosure 3
Main Control Board Handswitch
Enclosure 3
Main Control Board Handswitch
Enclosure 3
Main Control Board Handswitch
Enclosure 3
Operator Intervention
- The operator action had no impact on putting out the fire
- Switch is well placed in fire retardant enclosure making direct air flow to the point of combustion impossible
- The Condition Report assumes what the operator initially believed at the time, that he blew out the fire
- Switch will self-extinguish when current path becomes interrupted
- Operator action was inconsequential, testing shows the fire will self-extinguish anyway
Enclosure 3
Main Control Board
Enclosure 3
No Potential for Fire Spread
- Handswitch fire self-extinguishes
- Confirmed by testing
- Handswitch fire not of sufficient duration or intensity to ignite secondary combustibles
- Test thermocouples
- CHRISTIFIRE test results
- Fire resistive properties of cables and handswitch materials
- No hot gas layer formed within panel
- Conclusion: No potential for fire spread
Enclosure 3
NUREG/CR-6850 Appendix C Objective Classification Criteria NUREG/CR-6850 Objective Criteria FNP Event A hose stream, multiple portable fire extinguishers, and/or a fixed fire suppression system (either manually or automatically actuated) were used to suppress the fire No automatic or manual suppression used One or more components outside the boundaries of the fire ignition source were affected No evidence of any collateral damage outside of the fire ignition source Combustible materials outside the boundaries of the fire ignition source were ignited No ignition of secondary combustibles If any one of the following exist, the event is challenging
Enclosure 3
NUREG/CR-6850 Appendix C Objective Classification Criteria NUREG/CR-6850 Objective Criteria FNP Event Actuation of an automatic detection system Event did not produce sufficient smoke to actuate the main control room detection system. An ionization smoke detector is located on the ceiling directly behind Section C of the MCB A plant trip was experienced Event did not cause a plant trip. The unit was in cold shutdown.
A reported loss of greater than $5,000 Physical damage limited to the handswitch (< $1,000)
A burning duration or suppression time of 10 minutes or longer Burning duration was less than two minutes If any two of the following exist, the event is challenging
Enclosure 3
NUREG/CR-6850 Appendix C Subjective Classification Criteria NUREG/CR-6850 Subjective Criteria FNP Event It is apparent that active intervention was needed to prevent potential spread Operator blowing on the switch enclosure was insignificant intervention. Test data demonstrates the handswitch fire self-extinguishes There are indications that heat was generated of sufficient intensity and duration to affect components outside the fire ignition source No evidence of heat damage to any components outside of the fire ignition source There are indications that flames or heat was generated of sufficient intensity and duration to cause the ignition of secondary combustibles outside the fire ignition source No ignition of secondary combustibles Substantial smoke was generated Insignificant amount of smoke If any of the following exist, the event is Challenging
Enclosure 3
NUREG/CR-6850 Appendix C Subjective Classification Criteria NUREG/CR-6850 Subjective Criteria FNP Event It is apparent that active intervention was needed to prevent potential spread Operator blowing on the switch enclosure was insignificant intervention. Test data demonstrates the handswitch fire self-extinguishes There are indications that heat was generated of sufficient intensity and duration to affect components outside the fire ignition source No evidence of heat damage to any components outside of the fire ignition source There are indications that flames or heat was generated of sufficient intensity and duration to cause the ignition of secondary combustibles outside the fire ignition source No ignition of secondary combustibles Substantial smoke was generated Insignificant amount of smoke If any of the following exist, the event is Challenging
Enclosure 3
NUREG/CR-6850 Appendix C Objective Classification Criteria NUREG/CR-6850 Objective Criteria FNP Event Actuation of an automatic detection system Event did not produce sufficient smoke to actuate the main control room detection system. An ionization smoke detector is located on the ceiling directly behind Section C of the MCB A plant trip was experienced Event did not cause a plant trip. The unit was in cold shutdown.
A reported loss of greater than $5,000 Physical damage limited to the handswitch (< $1,000)
A burning duration or suppression time of 10 minutes or longer Burning duration was less than two minutes If any two of the following exist, the event is challenging
Enclosure 3
Non-Challenging Control Room Fires From Fire Events Database Involving Intervention Fire Incident No Description Type of Intervention 374 SDV high level RPS relay burned Control room personnel extinguished the burning relay 425 A relay burned due to its old age Portable CO2 extinguisher used 815 A relay burned up in the primary containment isolation panel Portable CO2 extinguisher used 2224 Defective insulation on windings led to fault within current protection relay Portable fire extinguisher used 2266 Small fire found in control panel transformer Operator blew out flame
Enclosure 3
Conclusion: Non-Challenging
- None of the objective or subjective criteria was met
- Event is non-challenging
Enclosure 3
SNC Risk Significance Determination
Enclosure 3
Fire Ignition Probability Will Fire Propagate?
Fire Severity Factor Non-Suppression Probability Shutdown outside MCR Risk Not Significant No Control Room Abandonment SDP Factors HRA Dominated (Unit 2)
Suppression before propagation to cable bundle Unit 1 MCR Panel Unit 2
Enclosure 3
Phase III Summary Fire Ignition Probability Propagation Probability Suppress before propagation to cable bundle MCR Abandonment Probability Shutdown outside MCR CCDP NRC 1.0 0.5 1.0**
1.1E-3 (upper)
5.6E-4 (lower)
9.9E-3 5.5E-6 (white)
2.8E-6 (white)
SNC 1.0 0.5*
1.0** (upper)
0.01 (realistic)
6.3E-5 6.4E-4 3.1E-3 1.0E-7 (green)
1.0E-8 (green)
- SNC Position - fire not challenging
- Considered in MCR abandonment probability
Enclosure 3
- HVAC Operation
- HVAC allows Main Control Room (MCR) to remain manned for larger fires
- Larger fires are less likely to occur
- Risk of Abandonment reduced by a factor of 20
- Both NRC and SNC used NUREG/CR-6850 methods
Enclosure 3
MCR Abandonment (cont.)
- NRC assumed HVAC inoperable
- HVAC controls/circuitry physically separated from fire location
- Operators and Fire Brigade would not trip HVAC
Enclosure 3
Farley Common MCR Fire Location HVAC Controls
Enclosure 3
Shutdown from Outside MCR NRC Value SNC Value Comments 9.9E-3 3.1E-3
- Dominated by loss of aux feedwater due to human error
- Equipment failure of AFW negligible
- Difference is due to modeling of human error
Enclosure 3
SDP Summary
- Even assuming a challenging fire and an event probability of 1.0, the CCDP is green
- HVAC was a operating normally making the likelihood of control room evacuation less
- SNC performed a more realistic HRA reducing the calculated risk
Enclosure 3
Corrective Actions
Enclosure 3
Root Cause of the Event
- No written work package generated for the replacement of the flex conduit. We stepped out of process mixing CM with PM
- No lift sheet
- No pre-job brief
- Management has not been successful in getting Maintenance to internalize Human Performance tool usage 100% of the time.
- No discussion of human performance tools when problem identified
- Skill-of-the-craft is accepted behavior
Enclosure 3
Corrective Actions
- Revised fleet procedures to define allowable work scope for minor maintenance, tool pouch work, and CR initiation.
- Maintenance personnel were trained using dynamic training methods.
- Implemented leadership action plan for Maintenance Superintendents. Accomplished with the assistance of leadership expert.
Enclosure 3
Conclusion and Wrap-Up
- The event is non-challenging as it does not meet the NUREG / CR 6850 criteria for challenging
- Tests revealed that the handswitch consistently fails at the same location, resulting in a self-extinguishing condition
- Target cables will not catch fire because heat rates are low.
- Modeling control room HVAC results in green risk.
- The event is not risk significant
- The event should be characterized as green