ML093240292

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Containment Delamination Update
ML093240292
Person / Time
Site: Crystal River Duke Energy icon.png
Issue date: 11/19/2009
From:
Progress Energy Carolinas
To:
Office of Nuclear Reactor Regulation
Saba F, NRR/DORL/LPL2-2, 301-415-1447
Shared Package
ML091880884 List:
References
FOIA/PA-2010-0116
Download: ML093240292 (30)
v • d • e


Text

Crystal River Unit #3 C

t i t D l i

ti U d t Containment Delamination Update November 20th 2009

Agenda

  • Introduction
  • Plant Overview
  • CR3 Containment Design Features
  • SGR Opening Sequence & Identification of Delamination Delamination
  • Investigative Approach
  • Condition Assessment
  • Root Cause Analysis (RCA)
  • Operational Experience (OE)
  • Design Basis Analysis (DBA)
  • Design Basis Analysis (DBA)
  • Repair Approach
  • Summary Comments / Questions y

2

Crystal River 3 Overview

  • Babcock and Wilcox Pressurized Water Pressurized Water Reactor
  • Location: Crystal River y

Florida

  • 2609 MWth
  • 838 MWe
  • Commercial Operations began 1976 began 1976 3

2009 Crystal River 3 Outage Overview Building a nuclear future for Florida customers

  • Routine refueling scope
  • Off line maintenance and fuel for 2 years y
  • Extensive steam plant work T ki d

f l OTSGR d i

  • Taking advantage of longer OTSGR duration
  • Steam plant efficiencies
  • Part of total ~15% Uprate Part of total 15% Uprate 4

Steam Generator Replacement (SGR)

Work Breakdown

  • Containment Opening
  • Lifting and Rigging
  • Lifting and Rigging
  • Cutting and welding 5

Extended Power Uprate (EPU)

Work Breakdown Generator Replacement

  • Stator, Rotor, Exciter Moisture Separators MSR Drain Coolers Lube Oil Coolers Feed Water Heaters Iso-Phase cooling Iso Phase cooling 6

CRYSTAL RIVER #3 CRYSTAL RIVER #3 DESIGN FEATURES 7

Fission Product Barriers Simplified Schematic Liner Concrete Concrete Tendons (horizontal)

Barrier # 3 - Containment Liner Barrier # 2 - Reactor Vessel & Coolant Piping Barrier # 1-Cladding Enclosing The Fuel Tendon depiction is for illustrative purposes and is not an exact scale 8

CR3 Containment Dimensions Dimension Value Containment Outside Dimension (OD) 137 ft 0.75 in

(

)

Dome Thickness 36 in Basemat Thickness 12 ft 6 in Li Thi k 0 375 i Liner Thickness 0.375 in Wall Thickness 42 in Buttress Wall Thickness 5 ft 10 in Vertical & Hoop Conduit OD 5.25 in

  1. of Vertical Tendons 144
  1. of Tendon Hoops 94
  1. of Tendon Hoops 94
  1. of Tendons per Hoop 3
  1. of Prestressed Dome Tendons 123 Tendons 9

SGR OPENING SEQUENCE &

SGR OPENING SEQUENCE &

IDENTIFICATION OF DELAMINATION 10

Steam Generator Replacement (SGR) Opening (between Buttresses 3 and 4)

SGR Opening Dimensions

@ Liner 23 6 x 24 9 23 6 x 24 9

@ Concrete Opening 25 0 x 27 0 11

Concrete Removal 12

Concrete & Liner Removal Sequence 1

2 3

4 13

Delamination Close-up 14

Location of the Delamination Note - Tendon depiction is for illustrative purposes and is not an exact scale 15

INVESTIGATION APPROACH INVESTIGATION APPROACH 16

Work Flow Summary Root Cause Analysis Performance Improvement International (PII)

Analysis Cross Check Performance Improvement International (PII)

(Dr Chong Chiu)

Condition Assessment Condition Assessment Construction Technology Laboratories (CTL)

Design Basis Analysis MPR Associates, Inc Implement Repairs Contractor - TBD Repair Alternatives Analysis p

y Structural Preservation Systems (SPS)

Analysis Cross Check 17

External Support

  • Condition Assessment & Laboratory Testing
  • NDT - Construction Technology Laboratories (CTL)
  • L b M

T S il& M t i l E i

(S&ME)

  • Labs - MacTec, Soil& Materials Engineers (S&ME)
  • Other Field Data - Sensing Systems, Inc; Core Visual Inspection Services (Core VIS), Nuclear Inspection & Consulting, Inc; Precision Surveillance; Gulf West Surveying Inc; AREVA
  • Root Cause Analysis Root Cause Analysis
  • Lead - Performance Improvement International (PII)
  • Owners Support - Worley Parsons, Bechtel 18

External Support (continued)

  • Design Basis Analysis
  • O S

t W

l P

  • Owners Support - Worley Parsons
  • Repair Analysis p

y

  • Lead - Structural Preservation Systems (SPS)
  • Owners Support - Wiss, Janney, Elstner, Inc (WJE)
  • Industry Support
  • Exelon, SCANA, and Southern Company 19

Organization - Functional View C

t i t

CEO

& Board Containment Project Manager Technical Interfaces Project Oversight &

Independent Nuclear Safety Oversight Analysis Root Cause Analysis Design Basis Analysis Interfaces NEI / INPO Controls Contract Administration Independent Review PNSC Oversight Committee Containment Sub-Committee Condition Assessment Repair Analysis NRC Scheduling NSRC Public / Media SMC/ Board Financial Nuclear Oversight 20

Nuclear Safety Oversight Committee (NSOC)

Containment Sub-Committee Membership Member Title Bob Bazemore (PGN)

VP-Audit (Chairman)

Joe Donahue (PGN)

VP-Nuclear Oversight Chris Burton (PGN)

VP - Harris Greg Selby Technical Director - EPRI Dr Shawn Hughes VP Shaw Stone and Webster Dr. Shawn Hughes VP - Shaw Stone and Webster Dr. Paul Zia Civil Engineering Professor, NCSU Hub Miller 33 years industry oversight experience ub e

33 yea s dust y o e s g t e pe e ce Darrell Eisenhut 41 years industry operation and oversight experience 21

CONDITION ASSESSMENT CONDITION ASSESSMENT 22

Condition Assessment Activities Completed or Planned

  • Determine Extent of Condition
  • Characterize the extent of delamination at the SGR opening
  • D i

di i f

h i

f

  • Determine condition of other portions of structure
  • Non Destructive Testing (NDT) of Containment Wall Surfaces
  • Use of Impulse Response (IR) Method
  • Comprehensive on external exposed surfaces Comprehensive on external exposed surfaces
  • Accessible areas in adjacent buildings 23

Condition Assessment Activities Completed or Planned

  • Concrete Cores
  • Used to confirm IR results (over 80 cores)
  • Visual examination of core bore holes with boroscope to identify if delamination present
  • Containment Dome Inspections
  • NDT IR scans in segment above the SGR opening
  • Concrete cores with boroscope examination of bore holes
  • Physical survey with established benchmarks 24

Condition Assessment Techniques Impulse Response (IR)

IR Equipment IR Performed in the Field IR Equipment Primary test method used in this evaluation IR Performed in the Field 25

Condition Assessment Techniques Ground Penetrating Radar (GPR)

Ground Penetrating Radar GPR Performed in the g

(GPR) Equipment Locates internal features (rebar, tendon conduits, etc.)

Field 26

Condition Assessment Techniques Core Bores & Boroscopic Examination Examination - Inward View Examination - Side View Core 51, Gap 1 Depth 5-1/4 Gap 1 Width Less than 1/8 27

Condition Assessment Techniques Impact Echo (IE)

IE Equipment IE Performed in the Field IE Equipment Ability to determine depth of delamination IE Performed in the Field 28

Plan View Turbine Bldg Intermediate Control C

l Heater Bay Bldg 1

2 6

Buttress #

(typical)

Intermediate Bldg Complex Fuel Transfer 3

5 4

Bldg 4

Source Drawing:

101-112 SH000 Seawater Auxiliary Bldg Fuel Pool Aux Bldg EDG Bldg Construction Opening 29

Containment Unfolded - Buttress 2 to 5 Updated Nov 18th, Mosaic IR Overlay scale is approximate 1

2 3

6 5

4 CL F

E D

Pour 15 Pour 16

- - - - - - - - - - - EL 240

- - - - - - - - - - - EL 250 EL 230 Buttress #2 Buttress #3 Buttress #4 Buttress #5 A

B C

D F

E A

B C

A B

C D

F E

M O

L K

J G

I H

Pour 12 Pour 13 Pour 14

- - - - - - - - - - - EL 230

- - - - - - - - - - - EL 220

- - - - - - - - - - - EL 210

- - - - - - - - - - - EL 200 SGR G

I H

J K

L M

O N

G I

H J

K L

M O

N SGR IR scans completed per PT-407T:

Blue = no delamination R

T V

W X

AA Z

S P

Pour 9 Pour 10 Pour 11

- - - - - - - - - - - EL 190

- - - - - - - - - - - EL 180

- - - - - - - - - - - EL 170 Aux Bldg Roof EL 167 8 SGR Opening P

R Q

S T

U V

X W

Z P

R Q

S T

U V

X W

SGR Opening Y

Actual IR scan output data:

AA Z

Pour 5 Pour 6 Pour 7 Pour 8

- - - - - - - - - - - EL 160

- - - - - - - - - - - EL 150

- - - - - - - - - - - EL 140 Intermediate Bldg Roof EL 149 0 Y

AA Z

AB AD AC Y

Z AA AB AE AF Y

Blue = no delamination Yellow= transition Red = delaminated 20 x 22 10 x 25 6 x 40 @

EL 164 EL 150 14 x

10 14 x

6 Pour 3 Pour 4 Pour 5 Pour 2

- - - - - - - - - - - EL 130

- - - - - - - - - - - EL 120

- - - - - - - - - - - EL 110 EL 100 Equipment Hatch AC AF AG Drawing scale is not exact EL 128 EL 128 8 x 15 Pour 1

- - - - - - - - - - - EL 100

- - - - - - - - - - - EL 90 CL CL CL CL 30 10 x 60 13 x 42 10x 16 Conclusion - IR scans with confirmation core bores identified delamination only in the Buttress 3-4 span above the Equipment Hatch, as shown in red above

Containment Unfolded - Buttress 5 to 2 Updated Nov 18th 2009 1

2 3

6 5

4 CL Pour 15 Pour 16

- - - - - - - - - - - EL 240

- - - - - - - - - - - EL 250 EL 230 Buttress #5 Buttress #6 Buttress #1 Buttress #2 B

C D

F E

A B

C D

F E

A B

C D

F E

Pour 12 Pour 13 Pour 14

- - - - - - - - - - - EL 230

- - - - - - - - - - - EL 220

- - - - - - - - - - - EL 210

- - - - - - - - - - - EL 200 G

I H

J K

L M

O N

G I

H J

K L

M O

N G

I H

J K

L M

O N

IR scans completed per PT 407T:

Blue = no delamination Pour 9 Pour 10 Pour 11

- - - - - - - - - - - EL 190

- - - - - - - - - - - EL 180

- - - - - - - - - - - EL 170 Fuel Transfer Bldg Roof EL 200 4 P

R Q

S T

U V

X W

Z P

R Q

S T

U V

X W

Q R

P Actual IR scan output data:

EL 180 10 x60 Pour 5 Pour 6 Pour 7 Pour 8

- - - - - - - - - - - EL 160

- - - - - - - - - - - EL 150

- - - - - - - - - - - EL 140 Intermediate Bldg Roof EL 149 0 Intermediate Bldg Roof EL 149 0 Y

AA Z

AB AD AC Y

AA Z

AB AD AC 8 x 16 EL 160 EL 143 Blue = no delamination Yellow= transition Red = delaminated D

i l

28 x 11 6 x 15 6 x 24 3 x 9 Pour 3 Pour 4 Pour 5 Pour 2

- - - - - - - - - - - EL 130

- - - - - - - - - - - EL 120

- - - - - - - - - - - EL 110 EL 100 9 x 12 EL 119 Drawing scale is not exact 11 EL 122 Pour 1

- - - - - - - - - - - EL 100

- - - - - - - - - - - EL 90 CL CL CL CL 31 8 x 12 Conclusion - No delamination identified in these Buttress spans

Core Bores Buttress Spans 2 4 - 5 (as of Nov 17th 2009)

Buttress # 3 Buttress # 4 Buttress # 5 Buttress # 2 32 Conclusion - Delamination is confined between Buttresses 3-4 span

Core Bores Buttress Spans 5 1 - 2 (as of Nov 17th 2009)

Buttress # 6 Buttress # 1 Buttress # 2 Buttress # 5 33 Conclusion - Core bore hole(s) boroscopic exams on these Buttress spans confirm the IR results, that no delamination has occurred

Core Borings Conclusion - Delamination has only been observed in core bore hole(s) boroscopic exams in the buttress 3-4 span, as accurately predicted by IR 34

Horizontal Tendons Buttress 2 - 4 Additional tendons to be detensioned prior to closing SGR opening (pre-outage plan)

Tendons Removed SGR Opening outage plan)

Additional tendons to be detensioned prior to closing SGR opening (pre-outage plan)

Source Drawing:

0425-006 SH001

- SH 000 SH 000 35

Horizontal Tendons Buttress 3 - 5 Additional tendons to be detensioned prior to closing SGR opening (pre-outage plan)

SGR Opening Tendons Removed g

p

)

Additional tendons to be detensioned prior to closing SGR opening (pre-outage plan)

Source Drawing:

0425-007 SH001

- SH 000 SH 000 36

Vertical Tendons Additional tendons to be detensioned prior to closing SGR opening (pre-37 Tendons Removed p

g (p outage plan)

CR3 Typical Tendon Schematic and Photo (for horizontal tendon # 53H27)

Source Drawing:

425-020-SH-001-SH000 38

Buttress # 3 Buttress # 4 Tendon Pattern Tendon Pattern at time of cutting SGR SGR Opening Removed Tendon Energized Tendon Opening Equipment Hatch area (tendons continue below)

(tendons continue below)

Buttress (typical)

CL CL 39

Buttress # 3 Buttress # 4 Tendon Pattern Tendon Pattern at time of cutting SGR Removed Tendon Energized Tendon Opening SGR Opening Equipment Hatch area (tendons continue below)

Buttress (typical)

CL CL 40

Wall Section Cutaway Wall Section at SGR Opening (elevation view)

Source Drawing:

Source Drawing:

425-033 SH000 41

Wall Section Cutaway (cont)

Bottom of Ring Girder g

Wall section at higher elevations showing additional stirrup reinforcement (elevation view)

Source Drawing:

425-033 SH000 42

Buttress Cutaway Buttress match-line Wall Section at SGR O i

SGR Opening (Plan View)

Source Drawing:

g 425-033 SH000 43

Equipment Hatch Opening Reinforcement Photo - 30 Nov 1972 44

ROOT CAUSE ANALYSIS ROOT CAUSE ANALYSIS 45

Root Cause Analysis - PII Metrics Un-refuted Failure Modes as of Nov 17th 2009 70 80 External Events 50 60 Operational Events Inadequate Containment Cutting 30 40 50 Inadequate Concrete - tendon interactions Shrinkage, Creep, and Settlement 10 20 30 Chemically or Environmentally Induced Aging Inadequate Use of Concrete Materials I

d t

C t

C t

ti 0

10 7-Oct 8-Oct 9-Oct 0-Oct

-Oct

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov

-Nov Inadequate Concrete Construction Inadequate Concrete Design due to High Local Stress 27 28 29 30 31 1-2-

3-4-

5-6-

7-8-

9-10-11-12-13-14-15-16-17-18-19-20-46

Root Cause Analysis Field Data Acquisition

  • Impulse Response (IR) Scans
  • Boroscopic Inspections
  • Boroscopic Inspections
  • Inside the delaminated gap
  • Visual inspections
  • Delamination cracks at SGR Opening
  • Larger fragments from concrete removal process
  • Containment external surface 47

Root Cause Analysis Field Data Acquisition (continued)

  • Nearby energized tendons lift-off (vertical and horizontal) horizontal)
  • Containment dimension measurements
  • St i

t

  • Strain gauge measurements
  • Linear variable displacement transducer (LVDT) it i

gap monitoring

  • Building natural frequency 48

Root Cause Analysis Field Data Acquisition (continued)

  • Core bores laboratory analysis
  • Petrographic Examination g

p

  • Modulus of Elasticity and Poissons Ratio
  • Density, Absorption, and Voids
  • Compressive Strength Splitting Tensile Strength and Direct
  • Compressive Strength, Splitting Tensile Strength, and Direct Tensile Strength
  • Accelerated Creep test
  • Accelerated Alkali Silica Reaction (ASR) test
  • Chemistry and contamination test
  • Scanning Electron Microscope (SEM) examination of micro-g p

(

)

cracking 49

OPERATIONAL EXPERIENCE (OE)

OPERATIONAL EXPERIENCE (OE) 50

Steam Generator Replacement (SGR) OE Type of Information Collected from the Industry

  • Architect Engineer and Constructor
  • Type of Containment and design pressure yp g

p

  • # of Buttresses
  • Concrete design strength requirement
  • Dimensions
  • Internal containment diameter and wall height
  • Containment cylinder wall and dome thickness
  • Containment cylinder wall and dome thickness
  • Tendons details (# vertical, # horizontal, # dome, strand diameter)
  • Liner thickness 51

Steam Generator Replacement (SGR) OE Type of Information Collected from the Industry (cont)

  • Reinforcement details
  • Whether concrete opening was made p

g

  • Was hydro-excavation used
  • And if so, equipment operating parameters
  • D t i

i d t il

  • Detensioning details
  • # by cutting
  • # by relaxation y
  • # of tendons removed/detensioned beyond the SGR opening 52

Concrete OE

  • Worley Parsons
  • 1976 dome delamination investigation and repair (as Gilbert /

Commonwealth)

  • Structural Preservation Systems (SPS)
  • Largest Concrete Repair Contractor in the US, 2nd largest Concrete Contractor (of any type) in the US Contractor (of any type) in the US
  • Defects, Damage, and Deterioration
  • Performs > 4,000 repair projects per year
  • 3,000 employees in 27 offices Nationwide, and London, Dubai &

Singapore Singapore

  • Wiss, Janney, Elstner, Inc (WJE)
  • Structural engineering and materials science firm specializing in Structural engineering and materials science firm specializing in failure investigations and problem solving
  • Specialist in structural condition assessments and design of repairs and retro-fits for reinforced and post tension concrete structures
  • Conducted original CR3 Structural Integrity Test (SIT)

Conducted original CR3 Structural Integrity Test (SIT)

  • 450 employees in 20 offices nationwide 53

1976 Dome Delamination Cause(1)

Compression - tension interaction failure occurred C

t ib ti Eff t

Contributing Effects Radial tension due to pre-stressing Thermal effects Tendon alignment Stress concentrations Shrinkage Combined with biaxial compressive stresses and compressive stresses and lower than normal(2) direct tensile strength of concrete 54 (1)Cause information taken from 1976 Final Report prepared by Gilbert / Commonwealth (2)Lower than normal (or typical), but above design requirements

1976 Dome Delamination Repair Approach Tendons detensioned (18)

Delaminated surface was removed Lower level cracks grouted with epoxy with epoxy New reinforcement placed New cap poured and cured New cap poured and cured Tendons partially re-tensioned (18) 55

DESIGN BASIS ANALYSIS DESIGN BASIS ANALYSIS 56

Design Basis

  • Reinforced Post-Tensioned Concrete Structure
  • Live and Dead Loads Live and Dead Loads
  • Wind (110mph @ 30 increasing to 179 mph @ 16610)
  • Tornado Wind (300 mph)
  • Tornado pressure (external pressure of 3 psig)
  • Seismic (OBE - 0.05 and SSE - 0.10)
  • Temperature Loads
  • A id t P (55 i )
  • Accident Pressure (55 psig)

CR3 FEA Model

  • 180 degree Symmetric model
  • Symmetry plane @ 150 degrees midway Between B tt 3 & 4 / 1 & 6 Buttress 3 & 4 / 1 & 6
  • 1/2 Opening, 1/2 Damage & 1/2 Hatch Modeled Explicitly
  • Concrete Model
  • Concrete Model
  • Brick elements for all components
  • Dome and Base modeled independently
  • Si lifi d i b

d b tt t

  • Simplified ring beam and buttress geometry
  • Constraint equations used to join dome and ring girder for meshing efficiency
  • Constraint equation used to model sloped surfaces of the hatch 58

CR3 FEA Model (continued)

  • Liner Model
  • Shell mesh with variable thickness
  • Sh d

d ith t i t i f

  • Shared nodes with containment inner surface
  • Tendon Modeling
  • H t

d d l d li itl f l

d

  • Hoop tendons modeled explicitly for release and re-tensioning
  • Vertical Tendons modeled explicitly for release and re-t i

i tensioning

  • Dome tendons modeled independently with forces ported to global model 59

Concrete Geometry Based on Gilbert Associates Drawings 60

Tendon Geometry Based on Prescon Drawings 61

Dome FEA Model 62

Ring Girder Model 63

Core Building Geometry - FEA Mesh Hoop Tendon Locations Defined 64

Core Building Geometry - Buttresses 65

Equipment Hatch Model 66

Liner 67

Tendon Loading The tendons are preloaded to a prescribed load magnitude.

The application of the tendon loads is achieved in the analysis using initial strain input An empirical formula has been developed to account for the loss of load as the distance from the anchor point increases:

e P

P ks)

(ma 0

+

=

  • Where:
  • Po

= preload magnitude

  • m

= friction coefficient 0

m friction coefficient

  • a

= inflection angle (0.16)

  • k

= wobble coefficient (0.0003)

  • s

= distance from anchor point

  • Tendon preloads used in analysis:
  • P0-dome

= 1635 Kips (1,215,000 lb. 40 years)

t l

= 1635 Kips (1 252 000 lb 40 years)

P0-horizontal 1635 Kips (1,252,000 lb. 40 years)

  • P0-vertical

= 1635 Kips (1,149,000 lb. 40 years) 68

Dome Force Vectors Ported to Global Model 69

FEA Model - Vertical and Hoop Tendons 70

FEA Model - Vertical and Hoop Tendon Supports 71

FEA Model - Hoop Tendons Couples and Supports 72

Hoop Tendon Forces 73

Planned Analysis

  • Existing Design Cases for Comparison
  • Planned Analysis Steps
  • Dead Load + Tendons
  • Gravity (.95 G)
  • Internal Dead Load (200 psf)
  • Tendons (1635 kips / tendon)
  • Remove Hoop + Vertical Tendons in SGR Opening
  • Remove SGR Opening

(

p

)

  • Include losses
  • Internal Pressure (55.0 psi)
  • Wind Pressure (0.568 psi)
  • Delamination(1)
  • Remove Additional Hoop &

Vertical Tendons

  • R l

th SGR Pl (2)

(

p )

  • Seismic
  • Accident Thermal
  • Replace the SGR Plug(2)
  • Repair(2)
  • Re-tension Tendons
  • SAVE P th D d

t M d l f

  • SAVE Path Dependent Model for Starting point to Run 5 Controlling Design cases 74 (1) Analysis will consider timing of delamination and specific concrete properties (2) Sequence of replacing SGR concrete plug and repair may be adjusted

Design Basis Controlling Load Steps

  • Restart the Re-tensioned Model and solve the following Controlling Load Steps
  • 1.5 Internal Pressure + Accident Thermal
  • 1.25 Wind + 1.25 Pressure + Accident Thermal
  • 1.25 Earthquake + 1.25 Pressure + Accident Thermal
  • 2.0 Wind + Pressure + Accident Thermal
  • Run Comparison to original building elastic design results 75

Preliminary Comparison of FEA Results to Extent of Condition Measurements NDE Measurements (figure not to scale)

Calculated Gap Status behind Delamination Calculated Displacements 76

REPAIR APPROACH REPAIR APPROACH 77

Repair Attributes

  • Incorporates and is compatible with Root Cause Analysis findings Design Basis Controlling Load Steps
  • Restores applicable design basis margins
  • Incorporates Extended Life
  • Long Term Surveillance and/or Maintenance Requirements
  • C t

t bilit

  • Constructability 78

Repair Alternatives Considered

  • Use-as-Is - Rejected
  • Anchorage Only - Rejected
  • Cementitious Grout - Rejected Cementitious Grout Rejected
  • Epoxy Resin - Rejected
  • Delamination Removal and Replacement - Selected 79

Simplified Overview of Engineering & Repair Work Flow Tentative - Subject to RCA and DBA Results MPR 3D Finite Element Analysis MPR Tendon Calculations De-tension EC Mod Phase 1 EC Mod Phase 2 y

SGR EC Mod (Rev)

De tension additional tendons P

ti f

I l

t P

t R i

Preparations for Final Repair Install crack arrest strategy Implement Final Repair Post-Repair Testing Failure Modes Analysis Update Final Root Cause Analysis Failure Modes Analysis Update 80

Post-Repair Testing Tentative - Subject to RCA Results Approach - ILRT and System Pressure Test ASME Section XI IWE for the liner and IWL for the concrete Concrete exterior will be visually examined prior to pressurization and following de-pressurization Evaluating other additional instrumentation based on the final repair th t i i l

t d d

d i b

that is implemented, and as driven by:

  • Root cause analysis NDE ill b i

d f t

d li l t NDE will be required for restored liner plate 81

Stakeholder Interactions

  • Prompt Notification of Regulator & Industry
  • Engagement of Critical Industry Organizations Engagement of Critical Industry Organizations
  • Nuclear Energy Institute (NEI)
  • Including Nuclear Safety Information Advisory Council (NSIAC)

Including Nuclear Safety Information Advisory Council (NSIAC)

  • Institute for Nuclear Power Operations (INPO)
  • Electric Power Research Institute (EPRI)
  • Continued Transparency with Regulator
  • Special Inspection Team (SIT)
  • Region and NRR/RES technical discussions
  • Periodic Updates with U.S. Licensees 82

Summary & Questions Questions Q

83

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