ML11279A252
| ML11279A252 | |
| 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: ML11279A252 (6) | |
Text
Duke Energy / NRC Pre-submittal Meeting Turbine Building HELB Event Overview HELB occurs in Turbine Building resulting in unit blackout(s) with failure of TDEFDWP.
(Assumed worst case scenario)
Maintain unit(s)
Maintain unit(s) stable in HSB from stable in HSB from MCR with HPI/
SSF PSW Perform assessment/repair of failed HPI/PSW 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 to HPI/PSW Perform natural circ cool down to 250 deg F and secure HPI (long term safe and stable condition)
Perform assessment/repair of LPI DHR components Transition to LPI DHR Notes All units operating @ 100% prior to event HELB committed plant modifications installed Detailed flow charts provided on pages 2 - 4 Event timeline provided on page 5 Acronym definitions provided on page 6 1
Duke Energy / NRC Pre-submittal Meeting Turbine Building HELB Event Details A HELB in the Turbine Building will not affect PSW or SSF HELB occurs in Turbine Building resulting in unit blackout(s) with failure of TDEFDWP.
(Assumed worst case scenario)
Affected unit(s) trip:
CR SROs enter EOP ROs perform IMAs and Symptoms Check and determine loss of RCP seal cooling and/or loss of SG DHR CR SRO directs a LO to perform AP/25, SSF EOP LO proceeds to SSF.
CR SRO directs OATC to perform EOP enclosure to align PSW power to HPI and PSW pumps 1 CR SRO directs OATC to perform EOP enclosure to re-establish RCP seal cooling with HPI and SG DHR with PSW pump 1 Page 3 1
PSW modification related procedure revision currently in development.
2
Duke Energy / NRC Pre-submittal Meeting Turbine Building HELB Event Details Page 2 Control Room SSF Actions Actions Natural circulation hot standby (HSB) conditions Natural circulation hot are established from the standby (HSB) conditions main control room: are established from the OATC verifies offsite SSF:
power available to PSW LO transfers control to building or aligns power SSF from Keowee hydro if LO powers SSF from necessary 1 SSF D/G OATC starts the PSW LO starts SSF ASW booster pump and pump primary pump 1 LO establishes RCP OATC establishes SG seal cooling via RCMU feed via PSW pump 1 pump for each affected OATC transfers unit.
credited HPI LO establishes SG components to PSW feed via SSF ASW power 1 pump for each affected OATC establishes RCP unit.
seal cooling via PSW LO cycles PZR heaters powered HPI 1 to control RC pressure PSW power is locally SPOC deploys SSF aligned to PZR submersible pump in heaters 1 intake canal PZR heaters maintain RC pressure 1 SPOC deploys SSF submersible pump in intake canal 2 Single failure criteria If PSW/HPI is successful, OATC directs LO to terminate AP/25 1 1
PSW modification related procedure revision currently in development.
Page 4 Page 4 2
HELB related procedure revision not yet in development.
3
Duke Energy / NRC Pre-submittal Meeting Turbine Building HELB Event Details Page 3 Page 3 Affected units are prepared for natural circulation cool down from main control At direction of TSC an room: assessment and repair of CR SRO transfers to nonfunctioning HPI /
the Blackout tab of the PSW components is EOP performed 1 CR SRO and OATC attempt to restore power OSM enters E Plan and TSC is activated CR SRO enters AP/
1700/035, Loss of SFP Cooling Upon completion of If required, TSC assessment and repairs arranges for local fire operating crew department to provide transitions RCP seal pumper truck to cooling and/or SG DHR replenish SFP inventory functions from SSF to per RP/1000/022 main control room 1 PSW power aligned to SSF and SSF D/G is secured Portable valve control panel installed and connected to CFT isolation valves per RP/
1000/022 Operating crew initiates plant cool down per Blackout tab of EOP 1:
Reactor vessel head vents are opened.
Crew initiates RC cool down by throttling open ADVs 1 Crew initiates RC de- HELB related procedure revision not yet in pressurization via development.
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 Long term DHR of LPI DHR provided by SGs components Transition to LPI DHR being fed with performed per per OP/1102/025 1 PSW 1 OP/1102/024 and RP/1000/022 1 4
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 back to HPI/PSW completed T=72 hrs, Transition from hot standby to hot shutdown initiated
- Previously established SSF activation times 5
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 E Plan - Emergency Plan EOP - Emergency Operating Procedure HELB - High Energy Line Break HPI - High Pressure Injection System HSB - Hot Standby IMAs - Immediate Manual Actions LO - Licensed RO or SRO LPI - Low Pressure Injection System MCR - Main Control Room OATC - Operator At The Controls Reactor Operator OSM - Operations Shift Manager PORV - Power Operated Relief Valve PSW - Protected Service Water System PZR - Pressurizer RC - Reactor Coolant RCMU - Reactor Coolant Make Up System RCP - Reactor Coolant Pump RO - Reactor Operator RP - Response Procedure SG - Steam Generator SPOC - Maintenance Single Point of Contact SFP - Spent Fuel Pool SRO - Senior Reactor Operator SSF - Standby Shutdown Facility TDEFDWP - Turbine Driven Emergency Feedwater Pump TSC - Technical Support Center 6