ML12166A203
| ML12166A203 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/24/2012 |
| From: | Duke Energy Carolinas |
| To: | Plant Licensing Branch II |
| Boska, John P | |
| Shared Package | |
| ML12145A704 | List: |
| References | |
| TAC ME8504, TAC ME8505, TAC ME8506 | |
| Download: ML12166A203 (19) | |
Text
Main Steam Isolation Valve License Amendment Request Oconee Nuclear Station May 24, 2012 FOR INFORMATION ONLY
Agenda Purpose of the Meeting Basis for MSIV Modification Description of MSIV Modification Regulatory Approach Schedule Closing Remarks 2
FOR INFORMATION ONLY
Purpose of the Meeting First Pre-submittal discussion regarding License Amendment Request (LAR) in support of installation of Main Steam Isolation Valves Initiate discussions between Duke Energy and the NRC so that there is a common understanding of the scope and content of the planned LAR, prior to submittal Scoping 10 CFR 50.59 drafted to identify the scope of the LAR Most efficient use of NRC and Duke Energy resources Will not request NRC review of modification Facilitate timely approval of materials needed to support the modification 3
FOR INFORMATION ONLY
Basis for MSIV Modification Part of major upgrades to Oconee Nuclear Station to improve plant safety and address longstanding licensing basis issues Safety Benefit Enhance Main Steam System integrity to support the Secondary Side Decay Heat Removal function of the Standby Shutdown Facility (SSF)
Tornado missile analysis (TORMIS) relies on target reduction achieved by isolation of the Main Steam piping in the Turbine Building Facilitates repair of plant equipment following damage to main steam piping in the Turbine Building Meets commitments associated with proposed updates to High Energy Line Break (HELB) and Tornado licensing bases Proposed update to HELB (outside containment) licensing basis credits MSIVs (LAR re-submitted 12/16/2011 ML12003A070)
Proposed update to tornado licensing basis credits MSIVs (LAR dated 6/26/2008 ML081840371) 4 FOR INFORMATION ONLY
Description of MSIV Modification A single seismic, tornado protected enclosure (MSIV Enclosure) per unit will be constructed New piping and valves will be installed in the MSIV Enclosure Main Steam Isolation Valves (MSIVs)
Main Steam Relief Valves (MSRVs)
Atmospheric Dump Valves (ADVs)
Power Operated Atmospheric Dump Valves (POADVs)
Majority of construction will occur online with tie-in to existing Main Steam (MS) piping occurring during outage 5
FOR INFORMATION ONLY
Modification Description 6
FOR INFORMATION ONLY
MSIV Enclosure Top View 7
FOR INFORMATION ONLY
MSIV Enclosure Pre-Outage 8
FOR INFORMATION ONLY
MSIV Enclosure Outage 9
FOR INFORMATION ONLY
Main Steam Isolation Valves Designed to close against HELB conditions in less than 5 seconds after receiving a close signal Passive features of valve increase reliability Automatic closure on Low MS Header Pressure provides MS system integrity to support SSF function Design reduces likelihood of inadvertent actuation (preliminary analysis of event - results comparable to turbine trip)
Remotely operated from the Control Rooms 10 FOR INFORMATION ONLY
Main Steam Isolation Valves 11 FOR INFORMATION ONLY
Additional Modification Scope Current MSRVs will be replaced with new valves Addresses obsolescence Flanged installation will facilitate maintenance and testing New POADV in MSIV Enclosure Allows operation from the Control Room Reduces Operator burden for mitigation of SBLOCA Turbine Building manual ADV design duplicated and protected in MSIV Enclosure 12 FOR INFORMATION ONLY
Main Steam Flow Diagram 13 FOR INFORMATION ONLY
Turbine Driven EFW Pump Steam Supply The Turbine Driven Emergency Feedwater (EFW) Pump licensing basis is maintained A station blackout (SBO) will not cause the MSIVs to close nor will it prevent the MSIVs from closing on a valid low MS pressure signal If an Main Steam Line Break occurs, the Turbine Driven EFW Pump is automatically stopped on low MS pressure in either MS header The Motor Driven EFW Pump aligned to the intact steam generator (SG) provides secondary side decay heat removal after the overcooling has been terminated If the Turbine Driven EFW Pump is desired with both MSIVs closed, steam could be supplied from another unit via the auxiliary steam system 14 FOR INFORMATION ONLY
Regulatory Approach Scoping 10 CFR 50.59 drafted to identify the scope of the License Amendment Request Duke Energy needs NRC approval of the Chapter 15 analysis methodology changes associated with the MSIV installation DPC-NE-3000-PA, Rev. 4a, Thermal Hydraulic Transient Analysis Methodology DPC-NE-3005-PA, Rev. 3b, Oconee UFSAR Chapter 15 Transient Analysis Methodology License Amendment Request will provide Technical Specification (TS) Bases changes and a new Selected Licensee Commitment for information UFSAR changes will be made under 10 CFR 50.71(e) following modification implementation 15 FOR INFORMATION ONLY
Methodology Changes DPC-NE-3000 changes:
Changes to describe actual plant configuration with MSIVs and how the RETRAN model of the MS line would be modified Realistic modeling of the MSIVs, their closing characteristics, and where they are located More accurate modeling of new piping layout, to better predict MS pressure distribution DPC-NE-3005 changes:
Explicit statement within Section 15 for Single MSLB, to clarify that the MSIVs are not credited for isolating the unaffected SG from the faulted SG 16 FOR INFORMATION ONLY
Regulatory Approach Continue to rely on the Turbine Stop Valves, required by TS 3.7.2, for design basis accident mitigation TS not required for MSIVs Add New Selected Licensee Commitment (SLC) to impose functionality requirements for MSIVs consistent with the other equipment that is controlled by SLC No changes required to TS 3.7.4 for ADV flow path Revise TS 3.7.4 Bases to define the required ADV flow path Revise TS 3.3.11 &13 Bases to indicate that Automatic Feedwater Isolation System will automatically close the MSIVs on low MS header pressure 17 FOR INFORMATION ONLY
Schedule MSIV Methodology LAR Schedule 1/31/2013 target date for submittal Request NRC approval by 1/31/2014 Planned MSIV Modification Schedule Unit 1 Fall 2014 Outage Committed Date -12/2014 Unit 2 Fall 2015 Outage Committed Date - 12/2015 Unit 3 Spring 2016 Outage Committed Date - 07/2016 18 FOR INFORMATION ONLY
Closing Remarks Initiate discussions to develop common understanding of the scope and content of the planned LAR, prior to submittal Scoping 10 CFR 50.59 drafted to identify the scope of the LAR Most efficient use of NRC and Duke Energy resources Will not request NRC review of modification Facilitate timely approval of materials needed to support the modification NRC approval of LAR requested by 1/31/2014 Supports first MSIV installation on Unit 1 in Fall 2014 outage 19 FOR INFORMATION ONLY