ML11279A253
| ML11279A253 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/06/2011 |
| From: | Duke Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation |
| Stang J | |
| Shared Package | |
| ML11279A250 | List: |
| References | |
| Download: ML11279A253 (7) | |
Text
Duke Energy / NRC Pre-submittal Meeting Tornado Event Overview Tornado strikes site resulting in three unit blackout with loss of TDEFDWP (Assumed worst case scenario)
Perform Maintain unit(s) at assessment and HSB from SSF for repair of HPI up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> components within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Transition from SSF RCMU to HPI and perform natural circ cool down to 250 deg. F Secure HPI and maintain unit(s) at 250 deg. F with SSF ASW (long term safe and stable condition)
Notes All units operating @ 100% prior to event Tornado committed plant modifications installed Detailed flow charts provided on pages 2 - 5 Event timeline provided on page 6 Acronym definitions provided on page 7 1
Duke Energy / NRC Pre-submittal Meeting Tornado Watch Tornado Event Details Declared Crew enters AP/06:
Makes PA Announcement Notifies Security and Keowee Hydro Station OSM evaluates need to preemptively staff SSF No Tornado Crew Goes To Warning Severe Weather Declared Enclosure Yes Crew Goes To Tornado Warning
Enclosure:
Dispatch one Unit 1 or Unit 2 LO to SSF to establish communication with Control Room All Ops personnel report to control room Prep for tornado Tornado strikes site resulting in three unit blackout with loss of TDEFDWP (Assumed worst case scenario)
All three units trip:
CR SROs enter EOP ROs perform IMAs and Symptoms Check and determine loss of function LO at SSF is directed to perform AP/25, SSF EOP LOs from other two affected units proceed to SSF Page 3 2
Duke Energy / NRC Pre-submittal Meeting Tornado Event Details Page 2 Control Room SSF Actions Actions Assessment and recovery Natural circulation hot actions are initiated: standby (HSB) conditions CR SRO transfers to are established from the the Blackout tab of the SSF:
EOP. LO at SSF transfers CR SRO and OATC control to SSF attempt to restore LO at SSF powers SSF power from SSF D/G OSM enters E Plan and LO at SSF starts SSF TSC is activated ASW pump TSC initiates LO at SSF establishes RP/1000/022 to RCP seal cooling via coordinate assessment RCMU pump for one
& repair activities 1 unit 1 CR SRO enters AP/ LO at SSF aligns SSF 1700/035, Loss of SFP ASW for each affected Cooling unit 1 If required, TSC LO at SSF establishes arranges for local fire SG feed via SSF ASW department to provide pump for one unit pumper truck to Additional LOs arrive replenish SFP inventory and establish SG feed per RP/1000/022 via SSF ASW and RCP seal cooling via RCMU pump 1 LO for each unit stabilizes unit in natural circulation hot standby (HSB) conditions SPOC deploys SSF submersible pump in intake canal Page 4 Page 4 1
Tornado procedure revision not yet in development.
3
Duke Energy / NRC Pre-submittal Meeting Tornado Event Details Page 3 Page 3 At direction of TSC, OP/1102/024, Plant Damage Assessment, is performed to verify the availability of systems/components needed to transition to hot shutdown conditions 1:
13.8KV line from PSW substation to PSW building is restored 4KV power is restored to PSW booster pump and pump configured for local starting 4KV power is restored to credited HPI pump and pump configured for local starting Damaged A & B HPI discharge header piping is repaired or isolated, as necessary Damaged RCP seal injection piping repaired as necessary.
Portable valve control panel installed and connected to RV head vents, PORV and CFT isolation valves PSW power aligned to SSF and SSF D/G is secured Damage assessment/repair completed 72 hrs Page 5 Page 5 1
Tornado procedure revision not yet in development.
4
Duke Energy / NRC Pre-submittal Meeting Tornado Event Details Page 4 Page 4 Upon completion of assessment and repairs operating crew transitions HPI functions from SSF to local control per OP/1102/025 1:
HPI pump cooling provided by PSW booster pump RCP seal cooling/makeup provided by HPI system and SSF RCMU system is secured SG feed provided by SSF ASW system SSF powered from PSW Operating crew initiates plant cool down per OP/1102/025 1:
Reactor vessel head vents are opened Crew initiates RC cool down by throttling open ADVs Crew initiates RC de-pressurization via PORV At 800 psig, core flood tanks are isolated Unit is stabilized in natural circulation hot shutdown conditions (250°F/300 psig)
Reactor vessel head vents are closed HPI system is secured Assessment/repair of LPI DHR Long term DHR provided by components Transition to LPI DHR SGs being fed with SSF performed per per OP/1102/025 1 ASW 1 OP/1102/024 and RP/1000/022 1 1
Tornado procedure revision not yet in development.
5
Duke Energy / NRC Pre-submittal Meeting Event Timeline T=0, Event Initiation (Loss of Function)
T=14 min, SSF ASW flow established to SGs*
T=20 min, SSF RCMU flow established*
T=75 min, TSC activated T=1.75 hrs, Diversion of SSF D/G service water flow to yard initiated*
T=2.00 hrs, Diversion of SSF D/G service water flow to yard completed*
T=3hr 20 min, SSF submersible pump deployed*
T=36 hours, Maximum time to initiate replenishment of SFP T=72 hrs, Assessment/repairs needed to transition to hot shutdown completed.
T=72 hrs, Transition from hot standby to hot shutdown initiated.
- Previously established SSF activation time 6
Duke Energy / NRC Pre-submittal Meeting Acronyms ADV - Atmospheric Dump Valve AP - Abnormal Procedure ASW - Auxiliary Service Water System CFT - Core Flood Tank CR SRO - Control Room SRO/Procedure Director D/G - Diesel Generator DHR - Decay Heat removal EOP - Emergency Operating Procedure E Plan - Emergency Plan HPI - High Pressure Injection System HSB - Hot Standby IMAs - Immediate Manual Actions LO - Licensed RO or SRO LPI - Low Pressure Injection System OATC - Operator At The Controls Reactor Operator OPS - Operations Department OSM - Operations Shift Manager PA - Public Address PORV - Power Operated Relief Valve PSW - Protected Service Water System RC - Reactor Coolant RCMU - Reactor Coolant Make Up System RCP - Reactor Coolant Pump RO - Reactor Operator RP - Response Procedure RV - Reactor Vessel SG - Steam Generator SPOC - Maintenance Single Point of Contact SRO - Senior Reactor Operator SSF - Standby Shutdown Facility TDEFDWP - Turbine Driven Emergency Feedwater Pump TSC - Technical Support Center 7