ML073410063
| ML073410063 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/06/2007 |
| From: | Duke Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML073410063 (23) | |
Text
'Duke FEnergy.
Duke Energy Oconee Nuclear Station Tornado/HELB Projects Status Meeting T.
-NRR Offices Rockville, MD December 6, 2007 10:00 a.m. - 12:00 p.m.
1
a Duke Duke Attendees
[VEnergy.
" Mike Glover, ONS Engineering Manager
- Rich Freudenberger, Tornado/HELB Projects
- George McAninch, Tornado/HELB Design Basis n Tim Brown, Project Manager - HELB
- Allen Park, Principal Engineer - HELB
" Steve Newman, Licensing Engineer - Tornado
" Jim Sumpter, Licensing Project Manager 2
'Duke Agenda iFEnergy.
- Opening Remarks
- Main Steam Line Break (MSLB) Mitigation Strategy
" Tornado License Amendment Request Fiber Reinforced Polymer Licensing TORMIS
" Status of Commitments
- Closing Remarks 3
Duke Energy.
Opening Remarks n Objectives of the Tornado/HELB projects remain:
Improve plant safety, and
- Establish a licensing basis that will stand the test of time.
U
Purpose:
address the last open item from the 11/30/06 mitigation strategy letter, and U Provide an update on the status of the project, including commitment status.
4
S Duke MSLB Mitigation Strategy U Energy.
Background
" Open item: Intended mitigation strategy for main steam line breaks and other HELBs that could result in the compromise of the main steam pressure boundary in the turbine building.
" Main Steam Isolation Feasibility Study Branch isolations - not feasible to construct Header MSIVs - feasible to construct Preliminary Scope (pending development of final design inputs)
- . Relocate Safety Relief Valves to a 'dead leg'
- . Re-route manual ADV piping to upstream of MSIVs
- . Add a "Power Operated ADV" on each header
- . Provide structural upgrades to Auxiliary Building
- . No re-route of TDEFDWP steam supply 5
, Duke
'Energy.
MSLB Mitigation Strategy Current License Basis m MSLB licensing basis includes 3 cases
- 3. Small break with operator action required to trip unit m Chapter 15 MSLBs include breaks up to the Valves in the Turbine Building Turbine Stop m Blowdown of both Steam Generators terminated by closure of Turbine Stop Valves m Branches (5 per header) isolated by Motor Operated Valves operated from Control Room 6
a Duke MSLB Mitigation Strategy V Energy.
Future Strategy a MSIVs:
Provide a stable platform for operation of SSF and PSW/HPI Obviate the need to use equipment in the Turbine Building to achieve safe shutdown Provide an assured means of MS pressure boundary control following damage in the Turbine Building Facilitate repair of plant equipment following damage in the Turbine Building 7
Duke Energy.
MSLB Mitigation Strategy Future Strategy
" Breaks upstream of proposed MSIVs
?ý Strategy unchanged - same 3 cases will apply
- Breaks downstream of proposed MSIVs Preliminary analysis - bounding overcooling mitigated by Core Flood injection PSW/HPI or SSF - used to recover from HELBs in the Turbine Building that result in a loss of 4160V power MSIVs will be manually "failed closed" during transfer to SSF or PSW Single failure criteria is not applicable because MSIVs will not be required for core protection Turbine Building EQ analysis will not be required 8
Duke MSLB Mitigation Strategy uWEnergy.
Schedule a Tentative schedule for MSIV installation is after completion of Natural Phenomena Barrier System and Protected Service Water/High Pressure Injection Projects Unit 1: Fall 2012 Unit 3: Fall 2013 Unit 2: Fall 2014 a Modification will require LAR TS revision to add MSIVs Revision of MSLB dose analysis to incorporate Alternate Source Term methodology.
9
a Duke Tornado LAR
[UEnergy.
- LAR in final development U Tornado design criteria applied to:
Containment Structure Reactor Coolant Pressure Boundary
- . Protected by Containment Structure
- . Letdown Line evaluated by TORMIS Safe Shutdown Systems
- SSF - protected or evaluated by TORMIS
- Preliminary TORMIS results (SSF only)
) near acceptance criteria
- PSW/HPI - backup to SSF - provides margin 10
Duke Tornado LAR EEnergy.
Fiber Reinforced Polymer
" Natural Phenomena Barrier System will use FRP for both block walls and brick walls Blowout panels discussed in August were determined to not be feasible after further evaluation of the design
" Cask Decon Tank Room (block walls)
" SER forecasted for February 2008
" West Penetration Room (brick walls)
LAR target date October 2008 Driven by testing program and separate LAR SER forecasted for October 2009
" Commitment change will be required 11
,Duke
'Energy.
Status of Commitments n Overall, good progress continues to be made U HELB Pipe inspection results
- HELB commitment revisions due to abandonment of
'inspections in lieu of protection' concept
- NPBS commitment change because of FRP delays.
- See Attachment 1 for overall status of commitments 12
Duke Energy.
Closing Remarks M
Questions / Discussion 13 Tornado Commitments 1T Physically protect the Unit 3 Control Room north wall from the effects of a tornado per associated UFSAR Class 1 structure tornado wind, differential pressure, and missile criteria.
12-2008 On Schedule 2T Physically protect the Standby Shutdown Facility (SSF) diesel 12-2007 fuel vents from the effects of a tornado per associated UFSAR Complete SSF tornado wind, differential pressure and missile criteria.
3T Analyze and/or protect as required, the elevated/exposed 12-2007 portions (at the north end of the of the Standby Shutdown On Facility (SSF) and where the SSF and CT-5 trenches intersect) of the SSF cable/pipe trench from the effects of a tornado per associated UFSAR SSF tornado wind, differential pressure and missile criteria.
4T Analyze and protect as required, each unit's Borated Water 12-2009 Storage Tank and associated piping per the UFSAR Class 1 Schedule in structure tornado wind, differential pressure, and missile criteria.
- Jeduledy, construction interaction with WPR/CDTR 5T Improve the protection of tornado mitigation equipment located 12-2009 within the West Penetration Room (WPR) and Cask Schedule Decontamination Tank Room (CDR) from the effects of a Impacted; FRP tornado. The WPR block walls will be upgraded to the UFSAR LAR not Class 1 structure tornado wind and differentli pressure criteria a
on using Fiber Reinforced Polymer. Duke will evaluate the need for schedule.
additional missife protection for the CDR/WPR wall using TORMIS.
6T Submit a License Amendment Request (LAR) to use Fiber Complete Reinforced Polymer (FRP) technology for application in Submitted strengthening selected masonry walls against the effects of 6/1/2006 tornado wind and differential pressure. The LAR will commit to utilizing technical procedures to control testing of concrete substrate and installation and inspection of the FRP systems and in-service inspection of the FRP system once installed.
7T Submit a License Amendment Request (LAR) establishing a 7-2007 new tornado licensing basis (LB) and mitigation strategy. The 1-208 LAR will address the two redundant mitigation systems, Standby Shutdown Facility (SSF) and Protected Service Water/High Revised by Pressure Injection (PSW/HPI) used in the tornado mitigation letter dated strategy.
6/28/07.
On schedule The LAR will commit to the following and include information concerning:
0 622-61 olo8MonteN of 1-14 Soloote10d Uo-C-GORMmitMo Chango to nUro Nooeniwng basis owait'; ad ""Mes cto The use of TORMIS to collectively assess certain SSCs (with the exception of the Keowee Hydro Units (KHU)) that support the Secondary Side Decay Heat Removal (SSDHR), Reactor Coolant Pump (RCP) Seal Injection or Reactor Coolant System (RCS) pressure boundary functions in the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after the event that are not currently protected in accordance with UFSAR tornado missile criteria.
The elimination of credit for the Spent Fuel Pool to High Pressure Injection (HPI) pump flow path.
0 In accordance with the CLB, single active failures will not be assumed in the updated tornado mitigation strategy.
0 A description of the upgrade of the current low pressure Auxiliary Service Water (ASW) system to a high head PSW system that can be actuated, aligned, and controlled from the main Control Rooms (CR) for SSDHR. This system will be credited for both tornado and HELB events.
The ASW upgrade also includes the installation of new PSW switchgear with alternate power provided from the KHUs via a tornado protected, underground feeder path.
The PSW switchgear and supporting equipment will be located in a new tornado protected building. Power will also be provided from the Central/Lee 1OOkV transmission line through a new transformer that will be located to further minimize concurrent damage of the station switchyard, KHU and the new transformer.
Specifically, the modification will provide alternate power for:
- 1. The PSW/HPI system itself,
Attaehmpnt 1
- 3. A sufficient number of pressurizer (PZH) heaters (also operated from the main CRs) to maintain a steam bubble in the PZR for RCS pressure control,
- 4. The existing vital instrumentation and control battery
- chargers,
- 5. The SSF SSCs in case the SSF diesel generator is unavailable,
- 6. RCS High Point Vent and Reactor Vessel Head Vent valves for boration and RCS inventory control. At least one high point vent is required to control RCS inventory at Safe Shutdown conditions.
8T Installation of the PSW/HPI modifications.
12-2010 On Schedule 9T A program will be developed to monitor site missile inventories.
12-2007 Complete 1 OT Verbally notify in advance the Deputy Director, Division of As necessary, Reactor Licensing of the NRC, followed by a written until 12-2010 communication, of significant changes in the scope and/or In progress completion dates of the commitments in Attachment 1 of this submittal. The notification will include the reason for the changes and the modified commitments and/or schedule.
High Energy Line Break Commitments HELB Piping Inspection Program 1 H Implement an inspection program that ensures the Auxiliary Complete Building Main Steam and Main Feedwater girth and accessible attachment welds are re-inspected at least once during each subsequent 10 year ASME Section XI In-service Inspection interval for weld flaws and thickness.
2H Unit 1, 03-2008 Implement an inspection program that ensures the following welds are re-inspected at least once during each subsequent 10 Unit 2, 09-2008 year ASME Section XI In-service Inspection interval for weld Unit 3, 03-2009 flaws and thickness:
On Schedule,
preparation
- b. Solootad TUri 6WIlding high onorgW piping girth lid 3H Complete initial ASME Section XI In-service Inspection interval 07-2008 ultrasonic testing of the Auxiliary Building Main Steam and Main On Schedule Feedwater girth welds and accessible attachment welds for weld flaws and thickness. Accessible attachment welds are to undergo visual examination for general weld quality as well as surface examination using either a magnetic particle or a liquid penetrant test.
4H Complete initial ASME Section XI In-service Inspection interval 03-2012 ultrasonic testing of the following welds for weld flaws and On Schedule thickness. Accessible attachment welds are to undergo visual examination for general weld quality as well as surface examination using either a magnetic particle or a liquid penetrant test:
- a. Other Auxiliary Building high energy piping critical crack locations at welds.
bh. Soiesoo-ad-Turbine Building high eneFWg piping" wel
.ds-C. 2~.Act1l-TrbTN. Bilding high oR.rAWl pi*ing 9i4i60l a-Mk loWt mn a w".
5H Implement an inspection program that ensures that accessible Complete piping base metal downstream of Main Feedwater isolation valves located in the East Penetration Room and not enclosed by the guard pipe receive an ASME Section XI In-service Inspection interval ultrasonic testing inspection at least once every 10 years.
6H Implement an inspection program that ensures the following Unit 1, 03-2008 piping base metal receive an ASME Section XI In-service Unit 2, 09-2008 Inspection interval ultrasonic testing inspection at least once every 10 years.
Unit 3, 03-2009
- a. Other Auxiliary Building high energy piping critical crack On Schedule, locations not at welds.
tied to LAR
- b. S~e oto.
T-rbin.B.i..i..
high..
- e. ery p.. i. criti. cl.
preparation 7H Complete the initial ASME Section Xl In-service Inspection Complete interval ultrasonic testing inspection of piping base metal downstream of Main Feedwater isolation valves located in the East Penetration Room and not enclosed by the guard pipe.
8H Complete initial ASME Section XI In-service Inspection interval 03-2012 ultrasonic testing inspection of the following piping base metal:
On Schedule
- a. Other Auxiliary Building high energy piping critical crack locations not at welds.
- h. 20lootod "ur, in Building high energy pIipig critiGS arack loanafima not at w.'ldc 9H Implement an inspection program that requires external visual Complete inspection of accessible attachment welds at the terminal ends inside the main feedwater guard pipe at least once every 10 years.
1 OH Complete initial visual inspections of accessible attachment 06-2007 welds at the terminal ends inside the main feedwater guard Complete pipes.
Repair of Electrical Penetration Enclosures Located in the EPR to the Correct Configuration 11H Inspect and repair the Unit 2 East Penetration Room electrical Complete penetration termination enclosures to their correct configuration.
Missing and/or damaged covers, gaskets, and fasteners will be repaired or replaced.
12H Inspect and repair the Unit 1 East Penetration Room electrical 422a,06 penetration termination enclosures to their correct configuration.
Complte Missing and/or damaged covers, gaskets, and fasteners will be repaired or replaced.
13H Inspect and repair the Unit 3 East Penetration Room electrical Complete penetration termination enclosures to their correct configuration.
Missing and/or damaged covers, gaskets, and fasteners will be repaired or replaced.
14H Create an inspection plan to select a portion of Units 1, 2 and 3 Complete enclosures to open and inspect for signs of internal debris and corrosion.
15H Revise station procedures and processes as needed to ensure 03-2007 penetration termination enclosures are maintained in their Complete correct configurations.
EPR Flood Prevention Modifications 16H Complete the design and installation of flood outlet devices for Complete the Unit 1 East Penetration Room.
17H Complete the design and installation of flood outlet devices for Complete the Unit 2 East Penetration Room.
18H Complete the design and installation of flood outlet devices for Complete the Unit 3 East Penetration Room.
19H Complete the design and installation of flood impoundment and 12-2007 exterior door flood improvement features for the Unit 1 East On Schedule Penetration Room 20H Complete the design and installation of flood impoundment and 12-2007 exterior door flood improvement features for the Unit 2 East On Schedule Penetration Room.
21 H Complete the design and installation of flood impoundment and 12-2007 exterior door flood improvement features for the Unit 3 East On S Penetration Room.
HELB Design and Ucensing Basis Reconstitution 22H Submit License Amendment Requests (LARs) to establish Unit 1, 03-2008 23H an updated HELB Licensing Basis and HELB mitigation Unit 2, 09-2008 strategy for Oconee Nuclear Station (ONS). The LARs will 24H address deviations from and clarifications of selected Unit 3, 03-2009 portions of References 6 (the Giambusso letter) and 7 (the On Schedule Schwencer letter) and the criteria that will be substituted or clarified. Each unit LAR will include licensing basis changes based on design basis documents replacing OS 73.2.
The first LAR will commit to the following and will also provide the analysis results for Unit 1.
" The LAR will outline the basic elements of Selected Licensee Commitment changes to ensure licensing basis clarity and component operability such that HELB mitigation capability is maintained.
" The LAR will identify Turbine Building (TB) high energy piping girth welds and critical crack locations at welds whose failure would result in adverse interactions impacting the ability to achieve safe shutdown (SSD) or cold shutdown (CSD), as appropriate, following a HELB event. Th.M
, w-le ar* e rofo*r*od C'Am-t-M.fenr. Ce 2W and 4IH as %
T ~ooted ;6 high en.Aeg pipig 9irth wekWo or M solctcd T high onorgy critical rack lcamtion at wedg Fespcefively.
- The LAR will identify TB high energy critical crack locations not at welds whose failure would result in adverse interactions impacting the ability to achieve SSD or CSD, as appropriate, following a HELB event. These volde aro rFeoReecd in Gemmitmont Wa OW anad AN aim oov high Onr oritc crak loatione not-at The LAR will identify crack locations in high energy piping other than Main Steam and Main Feedwater in the Auxiliary Building (AB) per the criteria in Commitments 22H-24H. These locations are referenced in Commitment #Ws 2H, 4H, 6H and 8H as "other AB high energy piping critical crack locations".
High energy systems will be defined as those systems with operating temperatures greater than or equal to 200 F or pressures greater than or equal to 275 psig. For those systems that operate at high energy conditions less than 1% of the total plant operating time or at high energy conditions less than 2% of the total system operating time, no breaks or cracks will be postulated.
" For piping that is seismically analyzed, i.e. stress analysis information is available and the analysis includes seismic loading, intermediate breaks will be postulated in equivalent Class 2 or 3 piping at axial locations where the calculated stress for the applicable load cases exceed 0.8(SA + Sh). Applicable load cases include internal pressure, dead weight (gravity), thermal, and seismic (defined as operational basis earthquake, OBE). Intermediate breaks will not be postulated at locations where the expansion stress exceeds 0.8SA.
Thermal stress is a secondary stress, and taken in absence of other stresses, does not cause ruptures in pipe. This approach is permitted by GL 87-11 as a deviation from Reference 6.
For piping that is not rigorously analyzed or does not include seismic loadinas. intermediate breaks will be postulated at locations as provided in BTP MEB 3-1 (Section B.1.c(2)(b)(i)). This MEB 3-1 section provides more detail than the associated requirements in Reference 6, as amended by Reference 7, so that the most adverse locations can be identified as required in these references..
Terminal ends are vessel/pump nozzles, building penetrations, in-line anchors, and branch to run connections that act as essentially rigid constraints to piping thermal expansion. A branch appropriately modeled in a rigorous stress analysis with the run flexibility and applied branch line movements included and where the branch connection stress is accurately known will use the stress criteria noted above for postulating break locations as noted above in the 6 th bullet. For unanalyzed branch connections or where the stress at the branch connection is not accurately known, break locations will be postulated as noted in the 7 th bullet above.
Reference 6, as amended by Reference 7, provided criteria to determine pipe break orientation at break locations and specifies that longitudinal breaks in piping runs and branch runs be postulated for nominal pipe sizes greater than or equal to four inches.
Circumferential breaks are to be postulated at the terminal ends. The design of existing and potentially new rupture restraints may be used to mitigate the results from such breaks, including prevention of pipe whip and alteration of the break flow. For ONS, longitudinal breaks will not be postulated at terminal ends.
For piping that is seismically analyzed (i.e. stress analysis information is available and the analysis includes seismic loading), critical cracks will be postulated in equivalent Class 2 or 3 piping at axial locations where the calculated stress for the applicable load cases exceed 0.4 (SA + Sh). Applicable load cases will include internal pressure, dead weight (gravity),
thermal and seismic (defined as operational basis earthquake, OBE). This approach is in accordance with BTP MEB 3-1 (Section B.1.e(2)) which is deviation from the requirements of Reference 7.
For piping that is not rigorously analyzed or does not include seismic loadings, critical cracks will not be postulated since -the effects of postulated circumferential and longitudinal breaks at these locations will bound the effects from critical cracks (See the 7 th bullet above).
Actual stresses used for comparison to the break and crack thresholds noted above will be calculated in accordance with the ONS piping code of record, USAS B31.1.0. (1967 Edition) Allowable stress values SA and Sh will be determined in accordance with the USAS B31.1.0 or the USAS B31.7 (February 1968 draft edition with errata) code as appropriate.
-Moderate energy line breaks will not be postulated.
Moderate energy rules were not in place when ONS was licensed and built and the effect of moderate energy cracks have not been evaluated.
Systems and components necessary to reach CSD will not be protected from HELBs. Station repair guidelines will be employed to effect repairs as required to those systems and components necessary to reach CSD. The affected unit will remain at SSD conditions while those necessary repairs are completed. Current damage repair guidelines and procedures will be enhanced, as necessary, to extend SSD capability beyond the 72-hour Current Licensing Basis (CLB) and to establish CSD.
The enhanced capability will not be part of the CLB or related to operability of the Standby Shutdown Facility (SSF).
A single active failure will be postulated in the Protected Service Water/High Pressure Injection (PSW/HPI) or SSF systems for the initial event mitigation as well as achieving and maintaining SSD. Single active failures will not be postulated during plant cooldown to CSD.
The LAR will include a provision to continue reliance on the CLB regarding application of the single failure criteria to the letdown piping.
Onsite emergency power distribution systems located in the TB will not be credited for mitigation of HELBs that could occur in the TB. New switchgear, to be installed as part of the PSW system, along with the SSF will be utilized for mitigation of HELBs that could occur in the TB.
The new PSW and the East Penetration Room flood prevention modifications will be designed and constructed to the quality standards applicable to a safety-related system.
A new time critical action will be created for the operators to place the PSW system into operation within 15 minutes following a complete loss of main and emergency feedwater with a complete loss of 4160 VAC power. A single HPI pump can be aligned to the Borated Water Storage Tank and started to reestablish seal cooling for the reactor coolant pumps. A new time critical action will be created for the operators to place HPI into operation (from PSW power) within 20 minutes following a complete loss of 4160 VAC power. The new time critical actions will be time validated in accordance with the current ONS standards for emergency procedures. The operator would then maintain SSD conditions and energize pressurizer heaters as necessary to maintain reactor coolant pressure within limits.
5H Verbally notify in advance the Deputy Director, Division of As necessary, Reactor Licensing of the NRC, followed by a written until 03-2012 communication, of significant changes in the scope and/or In progress completion dates of the commitments in Attachment 3 to this submittal. The notification will include the reason for the changes and the modified commitments and/or schedule.