ML12349A151

Licensee Slides from 12/12/2012 Public Meeting with Omaha Public Power District to Discuss Containment Internal Structures Issues to Support Restart of Fort Calhoun Station, Unit 1

ML12349A151
Person / Time
Site:	Fort Calhoun
Issue date:	12/12/2012
From:	Omaha Public Power District
To:	Lynnea Wilkins Plant Licensing Branch IV
Wilkins L
References
TAC MF0307
Download: ML12349A151 (58)

Text

Fort Calhoun Station Containment Internal Structures (CIS)

Introductions

• Omaha Public Power District (OPPD) - Fort Calhoun Station (FCS)

Bruce Rash - Recovery Director Terry Simpkin - Manager, Site Regulatory Assurance Brian Davis - Recovery Engineering Director Bernie Van Sant - CIS Project Engineering Lead Tom Dailey - CIS Project Manager Russ Placke - Design Engineer 2

Introductions - Cont Contd d

• Stevenson and Associates (S&A)

- Dr.

D T Tsiming i i T Tseng

- Mike Allison

- Doug Seymour

• Automated Engineering Services Corp. (AES)

- Eric Halverson

- Andrew Carmean

• Sargent & Lundy (S&L)

- P. K. Agrawal

• MPR Associates, Inc. (MPR)

- Caroline Schlaseman 3

Agenda Opening Remarks D i dO Desired Outcomes t

History and Identification of Containment Internal Structures (CIS) Issue Discovery Process and Extent of Condition Modeling Methodology, Inputs and Assumptions Licensing Basis and Operability Criteria Planned Actions for Restart Support for NRC Inspection Activities Post-Restart Actions Closing Remarks 4

Opening Remarks

• OPPD committed to safe restart of FCS

• Containment pressure boundary is unaffected by this issue

• Current calculations show containment internal structures (CIS) nonconforming but operable for outage g conditions

• Continue to evaluate the online case

• OPPD is determined to establish licensing g basis safety margins for CIS

• OPPD dedicated to support NRC inspection of CIS operability for restart 5

D i d Outcomes Desired O t

• NRC understanding and feedback on OPPD CIS operability criteria

• NRC understands OPPDs OPPD s path forward on resolution of CIS issue

• NRC inspection team is provided with solid foundation on CIS problem identification, scoping and resolution to support inspection planning 6

History and Identification of CIS Issue Bernie Van Sant CIS Project Engineering Lead 7

History and Identification of CIS Issue

• Issue involves the concrete containment internal structure (CIS)

• CIS involves:

- Support for plant components and systems inside containment

• CIS does not involve:

- Containment pressure boundary

- Steam Generator compartments or reactor cavity 8

Elevation 1013 9

History and Identification of CIS Issue

• Original Analyses of the CIS

-PPerformed f d hand h d calculations l l i iin accordance d with ih American Concrete Institute (ACI) 318-63 during the 1960s using the load combinations identified in Updated Safety Analysis Report (USAR) Section 5 5.11 11

- Atomic Energy Commission (AEC) review confirmed g was adequate design q p prior to issuance of operating p g license

- No significant design changes to CIS 10

History and Identification of CIS Issue

• Discrepancy discovered during an extended power uprate analysis for containment cooling water system pipe supports

- Loads on one beam at the 1060 elevation exceeded design capacity

- Extent of condition investigation initiated 11

Discovery Process and Extent of Condition

• Issues identified with original CIS calculations

- Incorrect, incomplete or missing calculations

- Inconsistencies between calculations and drawings

- Incomplete consideration of all load combinations

- Simple numerical errors 12

Discovery Process and Extent of Condition

• Extent of condition evaluation done for 2 beams:

B-59 B 59 and B-103 B 103

• B-59 did not meet working stress design (WSD) acceptance criteria

• Companion beam (B-58) also evaluated - did not meet WSD acceptance criteria 13

Discovery Process and Extent of Condition

• Extent of condition assessment expanded to samplingg of CIS on all three elevations

• 9 more beams and 1 column selected

• Assessment stopped after 6 beams - all beams did not meet acceptance criteria

• Given results, decision was made to completely reanalyze the CIS 14

Modeling Methodology, Methodology Inputs and Assumptions Russ Placke Design Engineer 15

Modeling Methodology, Methodology Inputs and Assumptions

• Built 3-dimensional model of CIS

• GTSTRUDLTM Version 29.1 selected for analysis

• GOTHICTM Version 8.0 selected for analysis of differential p pressure ((dP)) across CIS floors 16

M d li Methodology, Modeling M th d l Inputs I t and d Assumptions

• Performed rigorous analysis

• Design for dead loads, loads live loads, loads seismic loads, loads and pipe break pressure loads

• Confirmed as-built configuration through extensive t i walkdowns lkd

• Validated assumptions and input parameters

• Conducted challenge boards and independent third party reviews

• Analysis rigorously documented 17

M d li Methodology, Modeling M th d l Inputs I t and d

Assumptions CIS Model Description Doug Seymour (S&A) 18

Modeling Methodology, Methodology Inputs and Assumptions CIS Design Model Description

• Finite element frame analysis

• Loads evaluated include dead loads, live loads, seismic loads loads, and pipe break pressure loads

• Differential pressure load increased by dynamic load factor (DLF)

• USAR seismic response spectrum utilized 19

Modeling Methodology, Methodology Inputs and Assumptions CIS Design Model Different from Licensing Basis

• Modal analysis performed

- Includes flexibility of beams and columns

- Modal and directional responses combined in accordance with NRC Regulatory Guide 1.92

• Licensing Basis does not require modal analysis

- CIS taken to be vertically rigid above basemat

- Constant, Constant non-varying non varying vertical acceleration provided

• Design model more conservative than licensing basis 20

Reanalysis Elements Flowchart of foundational S&A reports FC08156 FC08157 p 12Q4070-RPT-001 S&A Report Q p 12Q4070-RPT-002 S&A Report Q Design Basis Review Walkdown Report FC08158 FC08159 FC08163 S&A Report S& epo t 12Q4070-RPT-003 Q 070 003 S&A Report S& epo t 12Q4070-RPT-004 Q 070 00 S&A Report S& epo t 12Q4070-RPT-008 Q 070 008 Structural Starting Point Discrete Loads Report Distributed Loads Report FC08164 S&A Criteria 12Q4070-RPT-009 12Q4070 RPT 009 Third hi d party reviews i were performed f d on each h element.

l 21

TM GTSTRUDL Model of CIS 22

Modeling Methodology, Methodology Inputs and Assumptions GOTHIC Model Description Andrew Carmean (AES) 23

Modeling Methodology, Methodology Inputs and Assumptions GOTHIC Model Description

• Analysis to more accurately calculate dPs across CIS floors for input to GTSTRUDLTM

- NUREG-0800 was used as guidance, specifically Section 6.2.1.2.II

- Conservative Assumptions

• No credit for heat sinks (increases dP)

• Conservative initial conditions were assumed

- Subdivided containment into 10 separate volumes

• Volumes V l andd flflow paths th b based d on plant l td drawings i

24

GOTHIC Model Volumes

• Vol. 1 - Upper Containment

• Vol. 2 - SG RC-2A

• Vol. 3 - RC-2B (994'-1009')

• Vol. 4 - Cont. Outer Annulus (1013')

• Vol. 5 - Cont. Outer Annulus (994')

• Vol. 6 - Pressurizer Room

• Vol.l 7 - Quench h Tankk Room Basement

• Vol. 8 - RC-2B (1009'-1028')

• Vol. 9 - RC-2B (1028'-1046')

• Vol 10 - RC Vol. RC-2B 2B (1046 (1046'-1056')

1056 )

25

M d li Methodology, Modeling M th d l I Inputs t and d Assumptions CIS Design Model Preliminary Results Russ Placke Design Engineer 26

Modeling Methodology, Methodology Inputs and Assumptions CIS Design Model Preliminary Results

• Model utilized modal analysis analysis, which is more conservative than licensing basis

• Of 135 beams, 47 beams did not meet acceptance criteria for working stress and/or ultimate strength

• Of 14 columns, 5 columns did not meet acceptance criteria for working stress and/or ultimate strength

• Design issues principally in beams that support the safety injection tanks, ventilation coolers or reactor vessel head laydown areas

• All beams and columns are currently operable 27

Licensing Bases and Operability Criteria

• Based on the design model results, an initial operability evaluation analysis has been performed

• Modeling methodology for the operability evaluation is different from the design model

• Comparison of licensing and operability evaluation criteria is discussed in subsequent slides

• Continuing to refine operability evaluation analysis to ensure adequate conservatism and margin 28

Licensing Bases and Operability Criteria

• CIS DDesign i P Purpose

- Licensing Basis

• Functional integrity with licensing basis design margins under the most extreme environmental loadings

- Operability Criteria

• Structure functions to support equipment and system operability and safe shutdown functions

• Primaryy Code

- Licensing Basis and Operability Criteria

• ACI 318-63 29

Licensing i i Bases B and d Operability O bili Criteria

• Loads considered

- Licensing Li i Basis B i and d Operability O bilit C Criteria it i

• Dead loads (D)

• Live loads (L)

( )

• Accident pressure loads (Pc)

• Design earthquake loads (E)

• Maximum hypothetical earthquake loads (E)

(E )

30

Licensing Bases and Operability Criteria

• Load Combinations

- Licensing Basis

• Working Stress D L and D+L dD D+L+E L E

• No Loss of Function D+E D+L+E D+/-0.05D+1.5Pc D+/-0.05D+1.25Pc+1.25E D+/-0.05D+Pc+E

- Operability Criteria

• Same as Licensing Basis for No Loss of Function 31

Licensing Bases and Operability Criteria Doug Seymour (S&A) 32

Licensing Bases and Operability Criteria

• Ductility

• Ductility not permitted (licensing basis)

• Ductility not used (operability criteria)

• Material Properties

• Concrete strength for CIS not specified in licensing basis (design basis for CIS is 4 ksi)

• Concrete 28-day strength test data rolling average (operability criteria for CIS is 5.5 ksi)

• Seismic S i i Modeling M d li

• The CIS is considered vertically rigid per the USAR, Appendix F, Revision 8, Section 2.5 (licensing basis and operability criteria) 33

Licensing Bases and Operability Criteria

• Moment Redistribution Redistrib tion Licensing Basis and Operability Criteria

• Per ACI 318-63, Section 1502(d)

( )

• Damping for Concrete Structures Licensing Basis and Operability Criteria

• 2% for design earthquake (E)

• 5% for maximum hypothetical earthquake (E)

• Success Criteria Licensing Basis and Operability Criteria

• Interaction Ratio = demand/capacity

- Less than or equal to 1.0 34

Summary of Licensing Bases and Operability Criteria Differences

• Differences Between Licensing Basis and Operability Criteria Item Licensing Basis Operability Criteria Purpose Functional integrity with Structure functions to licensing basis design margins support equipment and under u de tthe e most ost e extreme te e system ope syste operability ab ty aand d

environmental loadings safe shutdown functions Load Combinations Working stress design and no No loss of function loss of function CIS Concrete Strength CIS concrete strength not 5.5 ksi specified in licensing basis (design basis for CIS is 4 ksi) 35

Licensing Bases and Operability Criteria

• Conservatisms in Operability Criteria

- Increase in concrete strength g from ageg hardeningg is conservatively neglected

- Ductility and increased damping for the dynamic pressure loading p g is conservatively y neglected g

- Higher permissible moment redistribution, which later concrete codes permit, is conservatively neglected

- Stair live loads used are conservatively high

- Damping and ductility for lateral seismic loads on laterally-unrestrained beams are conservatively g

neglected 36

Operability Assessment Preliminary Results

• Outage Case

- All structural members in CIS are operable - meet no l

loss off function f ti load l d case acceptance t criteria it i

• Normal Operation Case

- 3 beams exceed 1.0 interaction ratio

- Continuing to refine analyses, assumptions, and inputs 37

Pl Plannedd Actions A ti for f Restart R t t Brian Davis Recovery Engineering Director 38

Pl Planned d Actions A ti for f Restart R t t

• Issue final calculations December 20 20, 2012

• Third party review of calculations December 28, 2012

• Address third party review comments January 4, 2013

• V if commentt resolution Verify l ti J January 8 2013 8,

• Owner acceptance review January 11, 2013

• Issue operability evaluation January 11, 2013

• NRC inspection of operability evaluation during January 2013

• Continue engineering and construction planning activities 39

Support for NRC Inspection Activities

• Pro Provide ide availability a ailabilit of calc calculations lations and operability evaluation

• Support technical teleconferences as needed

• FCS site familiarization and CIS walkdowns

- Proposed - Week of January 7 7, 2013

• Modeling reviews in Boston, MA

- Proposed - Week of January 14 14, 2013

• FCS onsite inspection or additional visits to Boston MA as needed Boston, 40

Post Restart Actions

• Optimize modification designs

• Complete engineering change packages for modifications

• Install modifications during future outages 41

Design Options Tom Dailey CIS Project Manager 42

Design Options

• Structural Steel

- Easiest to design g and install

- Discounted due to thermal expansion-induced loads on columns

• Precast Concrete

- Caused excessive interferences along haul path

- Required large footprint to up-end column sections

- Excessive weight g has inherent handling g & rigging gg g risks

• Cast-in-place Concrete (current preferred option)

- Fewer interferences compared to structural steel and precast concrete option

- Formwork can be transported manually

- Proven methodology, less labor and shortest duration 43

Modification General Areas 44

Mod-1 General Arrangement 45

Mod-1 General Arrangement 46

Mod-1 General Arrangement El 1060 El. 1060 47

Mod-2 General Arrangement 48

Mod-2 General Arrangement 49

I t ll ti Challenges Installation Ch ll

• Numerous interferences

- 4 kV reactor coolant pump motor cable/conduit

- Large ventilation ductwork

- Conduit banks

- Component Cooling Water piping

- Pipe p supports pp

- Miscellaneous steel platforms, stairs, etc.

• Containment configuration not conducive to material handling

• Concrete must be pumped long distances 50

Typical Interferences 51

Typical Interferences 52

Typical Interferences 53

Modification Analysis Bernie Van Sant CIS Project Engineering Lead 54

Modification Analysis

• Analyses required to complete CIS engineering change packages

- Finalize structural analysis of CIS

- Optimize design of new columns and beams

- Design relocation of interferences

• Seismic and hydraulic analysis of piping rerouting

• Seismic and cable analysis for conduit rerouting

• Seismic and air flow analysis of ductwork rerouting

• Structural analysis of new commodity supports 55

Other Design Considerations

• IImpact on other h analysesl will ill h have to bbe addressed

- Containment pressure analysis

- High energy line break analysis for columns and relocated equipment q p

- Containment sump analysis

- Other analyses, as required 56

Closing Remarks Bruce Rash Recovery Director 57

Closing Remarks

• OPPD committed to safe restart of FCS

• Containment pressure boundary is unaffected by this issue

• Current calculations show CIS nonconforming but operable for outage conditions

• Continue to evaluate the online case

• OPPD is determined to establish licensing basis safetyy margins g for CIS

• OPPD dedicated to support NRC inspection of CIS operability for restart 58