ML072670108

9/06/2007 Waterford Steam Electric Station, Unit No. 3 - Meeting Handouts

ML072670108
Person / Time
Site:	Waterford
Issue date:	10/10/2007
From:	Entergy Operations
To:	Office of Nuclear Reactor Regulation
Kalyanam N
Shared Package
ML072670094	List: ML072670102 ML072670108
References
Download: ML072670108 (58)

Text

Entergy - Waterford 3 Meeting with NRC on Steam Generator Batwing Issue September 6, 2007 1

Introduction

• Nuclear Safety Priority

- Conservative Operational Assessment

- Defense in depth mitigation strategy

- Conservative monitoring and action limits

- Heightened awareness (ODMI)

- Conservatively performing a mid-cycle

• Meeting Objectives

- Inspection scope

- Expected findings

- Contingency criteria and planning 2

Agenda Discussion Topic Presenter Time Overview of Batwing Keith Nichols 5 Mitigation Strategy Steam Generator Monitoring Keith Nichols 5 Update Mid-Cycle Planned Activities Rex Putnam 30 Mid-Cycle Contingencies and Rex Putnam 40 Criteria Mid-Cycle Communication Bob Murillo 5 Plan Summary and Q&A Joe Kowalewski 10 3

Overview of Batwing Mitigation Strategy Keith Nichols 4

SG 32 - Status

• 22 broken batwings in stay cavity region

• Wrap Around Bar welds in the stay cavity region have been inspected and reinforced except BW at Column 84/85 (cold leg)

• Column 84/85 (cold leg) batwing slid into the tube bundle

- held in place by tube friction

- Adjacent tubes were plugged, sentinel plugged, or plugged and stabilized 5

Waterford ý3 Steam Generator 32 Batwing Inspection from Lower Handhole Approximate Position of Slotted Bar HL Batwing with Broken ..

Weld (Columns 1081109) Approximate Original Location of CL Batwing with Broken Weld 44 '4 ~44~'.

(Columns 84/85 Cold Leg) 44 44 44~ 44'~~4~

Batwing Tube Support "444 444444 4'

'.444 444 4 "<".44 Approximate Location Broken at Notch >i 4444 j '44444 >44 RF13 Batwing Failures 44 ~444> ~'.

(Columns 82/83/84) 4'4.4

'..444.444

.'4444.

~444 4 44 4 4444 K

Cold Leg Hot Leg

~4~44 44 '"' ' 444>4 4444 r Loose Batwing Bar 4 4 2 Batwings Broken at Weld

.. 4*

44 9'. ".9~

44~

~44 4

'44 44 4 444 44 Abrasive Wear 6 On Top Support Plate

Refuel-14 Repairs Defense-in-depth mitigation strategy

- Analysis of potential loose parts

- Analysis and validation of tube wear rates

- Analysis of forces on welds for batwing to wrap around bar

- Batwing welds to wrap around bar in SG 2 enhanced for batwings that traverse through stay cavity

- Inner row of tubes around stay cavity and loose batwing are plugged and stabilized

- Sentinel plugs added in on wrap around bar perimeter, around stay cavity and around loose batwing 7

SG - 32 TUBE REPAIR HISTORY RF 13 AND RF14 - E,,"4 Watefford RF0.1 z ,,%T, 3 -. 1C L I - --

• LC'NG S T AE.1 1

-::-R # 7 STAY PCSIT:ON

• c 772P , c~ci 1

i3 Li 22

.22

'4l 22 i

ilH 443

'I 7-4 .~1 7-7,0

--. 7-1: -777:7. 7 7

'.2 A

.0. .. . .. .0. .. .0 4 4.2 2'.

• 44 22 is. 00070 704 - ~2 4.4 77. ..

1 1,:ýH 1 L.- A PA. fa IE S '.4s I; IVi l+'Q M Ile 1W. 100 ýI Sý Ai A S . -V r I Preventive Plugging also in SG#1

Steam Generator Monitoring Update Keith Nichols 9

SG Monitoring Update Summary

" Dedicated loose parts monitor installed to monitor SG

- No metallic impacts identified

" Operational Decision Making Issue for primary to secondary leak rate

- 0.5 gpd steady and consistent with previous cycle

- 2 gpd and 5 gpd triggers increased monitoring and evaluation

- 5 gpd with a rate of 7.5 gpd/hr administrative shutdown

- 15 gpd administrative shutdown

• High level of site awareness and sensitivity

- Seven tube leak simulator training sessions this year with each operating crew

- Operations, Engineering and Chemistry monitoring 10

Steam Generator Primary to Secondary Leak Rate 3.00-2.50 2.00 4 a.

1.0 0

1.00 0.00 1/1/04 7/19/04 2/4/05 8/23/05 3/11/06 9/27/06 4/15/07 11/1/07 Date 11

Mid-Cycle Planned Activities Rex Putnam 12

Mid-Cycle Inspection Purpose

" Visually inspect the secondary side of the steam generators for the purpose of:

- determining any unforeseen extent of condition

- determining any unforeseen change in the critical variables that were the basis for the repair plan and operational assessment

• Secondary inspections will confirm no unforeseen changes

- BW to Wrap Around Bar Interface [Weld, Clip, Deformation]

- Examine Stay Cavity (Bottom Up) for Visible Deformation of the Tube Bundle

- A BW segment extending beyond the Seventh Eggcrate Support

- A BW segment outside of the stay cavity region

° Conservative Operational Assessment

- RF14 Operational Assessment predicted margin for all mechanisms

- Batwing related tube wear model was validated in RF14

- Forces (and thus wear) attenuates as the batwing extends further into the tube bundle

- Open tubes would not be impacted until after the Sentinel plugged tubes

- Sentinel plugged tubes remain intact

- Active tubes are not expected to have significant wear for 16 years 13

Mid-Cycle Inspections Secondary visual exam of upper batwings

° verify no upper batwing weld/clip failures in stay cavity area

• verify no gross deformation twisting of wrap around bar Foreign object search and retrieval

• remove accessible foreign objects

° no batwing segment outside of stay cavity Secondary.visual inspection of stay cavity area

• monitor batwing degradation

• verify that batwing at column 84/85 cold leg has not dropped Secondary diagonal visual inspection of upper stay cavity area (SG2 only)

• provide additional information in support of repair options in RF15 14

Upper Batwing Visual Inspection

" Critical Variable: No additional batwings have slipped into the tube bundle and no wrap around bar deformation

" Inspection: Visual exam to verify no upper weld failures for batwings instay cavity area and no gross deformation twisting of wrap around bar

" Analysis: Wear growth rates and wear distribution.

15

FOSAR Inspection e Critical Variable: No large mass foreign objects

• Inspection: Foreign object search and retrieval and visual inspection

• Analysis: Ginna tube rupture event analysis jinvolved the repeated impacts of a large mass foreign object over several years.

16

FOSAR Inspection 9 Critical Variable: Effectiveness of stabilizer fence for containing loose segments and maximum size of loose batwing segments in stay cavity 0 Inspection: Visual exam of stay cavity region and FOSAR to verify no large batwing segments or segments outside stay cavity e Analysis: Broken batwing analyses assumed containment of BW segment in stay cavity region to evaluate acceptabilityof tube impacts and wear, including normal and accident condition 17

Visual Inspection of Stay Cavity

• Critical Va riable: No extruded batwings 0l1 nspection: Visual inspection of stay cavity area for extruded BW segments 9 Analysis: Loose parts analysis for impact and wear. Note that attenuation analysis is conservatively based on a maximum force determined by BW materialplus sail area.

18

450 Inspection

• Provide additional information for RF15 repair options

• Inspection contingencies are developed 19

Expected Batwing Condition

• SG#1

- Upper batwing welds should be intact.

- Stay cavity damage has not been observed, but is possible. A mitigation strategy similar to that used in SG2 was applied in SG1 in RF-14.

• SG#2

- Upper batwing welds/clips and wrap around bar should be intact

- Propagation of batwing damage in the stay cavity is expected

- No indications of gross tube deformation is expected

- Column 84/85 batwing may move but is not expected to damage the stabilizer fence or active tubes

- Stabilized tubes around the stay cavity may have visible through wear but tube and stabilizer are expected to remain structurally intact

- No gross tube damage is expected 20

Secondary Inspection Techniques 21

Wrap Around Bar Inspection Tooling

• Access wrap around bar from steam drum

• Guide hooks on the wrap around bar

• Video probe inserts into guide tube for inspection

Wrap Around Bar Inspection Results

'C" ~

23

Lower Batwing Visual Inspection Tooling

• Installs through secondary 4 handhole at *....., :* . . . .*.}"..*!

tubesheet/ *:~~~~.. . ..*......*:.*

18x fixed I.....'"-

magnification K___________

24

Waterford 3 Steam Generator 32 Batwing Inspection from Lower Handhole Approximate Position of Slotted Bar HL Batwing with Broken S*

Weld (Columns 108/109) . Approximate Original

• ,,*.:** ...!. . Location of CL Batwing with Broken Weld (Columns 84/85 Cold Leg)

Batwing Tube Support Approximate Location 4...

Broken at Notch 4.'

RF13 Batwing Failures (Columns 82/83/84) 44.4.4~4.~

'-A'

,.*. .*;*.*;.*j ....*

• Cold Leg Loose Batwing Bar

~ ..- 4., . 44444'4~ 44.4.

44444~.444.".

~ .444~

44*

44 ~ 44.44 4 '4 2 Batwings Broken at Weld Abrasive Wear 25 N

On Top Support Plate

Area to be examined where Batwings enter tube bundle (heavy line)

Cutaway of central stay cavity 26

First of a Kind Diagonal Inspection 0-090' TYP 0.66SIR, 0.5.

.......... VETPERODI OT1 0.09(r 1yý

-.0 SI] TC UPPER TUBE BUNDLE SLUDGE LANCING (Flowstream Width = 0.48 in.)

27

Waterford Project Overview

• Diagonal Inspection Development Milestones Westinghouse Letter LTR-NFSM-07-118 "Diagonal Inspection and April 07 Mockup Requirements" Brooks Specification FS 55-05 "Diagonal Inspection Specification May 07 Requirements" Mockup and Tooling Design June 07 Mockup and Tooling Material Procurement June 07 Lower and Upper Mockup and Tooling Fabrication July 07 Video Probe and Tooling Prototype, Dry Mockup Testing August 07 Video Probe and Tooling Prototype, Wet Mockup Testing August 07 Video Probe and Tooling Final Design Development August 07 Video Probe and Tooling Final Manufacturing and Testing September 07 Video Probe and Tooling Qualification Testing September 07

• Mockup Tests were witnessed by Westinghouse and Waterford 3 personnel at Brooks 28

Mock-up of Upper Stay Cavity

• Simulates the upper7 stay cavity region ...

• Limited draw back space (21)

-- Jam Uio -

29

Mock-up of Upper Stay Cavity 450 Inspection

• This is a view of the mockup .

showing the tube to batwing interface Mockup test is underwater in dark environment .

Guide tube is .40" thick in a .48 gap Area of interest for '

diagonal inspection 30

Mock-up of Upper Stay Cavity

• Mock-up is inthe tank and includes platform to closely represent correct distance to entry point

~ 17 A

~L4

~ ~-~---

y

~

I.

31 V

Mock-up of Upper Stay Cavity 450 Inspection Mockup photo from video probe in wet and "

dark environment 450 inspection mock-up testing was successful ,K ,

- Able to see tube to batwing interface

- Able to see tube and batwing degradation

- Able to see 1-3 tubes in bundle Batwing to tube interface 32

Mid-Cycle Planned Activities Summary

• Secondary inspections (Upper, Lower and FOSAR) will verify that the critical variables used for the repair plan and operational assessment are met

• 450 inspection mock-up testing has been successful and will help establish RFI5 repair plan 33

Mid-Cycle Contingencies and Criteria Rex Putnam 34

Contingency Planning

• The potential outcomes of each secondary inspection activity were evaluated

• Appropriate contingencies planning has been taken SA .comprehensive decision flow chart has been prepared

• As found conditions will be evaluated and contingencies implemented as necessary 35

Decision Matrix Purpose

• Assures a consistent pre-thought decision for credible secondary inspection outcomes for conditions that cannot be accepted

- Reviews assure consistency with technical analyses

- Used to establish level of contingency planning and resource allocation

" Assures a thorough communication of specific decisions and criteria

" Facilitates rigorous and timely decision-making during the outage

" Labeled decision blocks and actions have written guidance explaining criteria and intended actions Color coded for previously described contingency action 36

Mid-Cycle Outage Contingencies

• Decision chart contingencies are color coded for ease of use.

- Eddy Current Test

- Install new 6" Access Port

- Batwing Weld Repair

- Batwing Stabilization 37

Wrap Around Bar Inspection Contingencies (Chart I)

Weld/clip failures in stay cavity area

• Indicated by irregular spacing and detached batwings with separation to a weld remnant on the wrap around bar and comparison with as-left video from RF14.

• If batwing has migrated into the tube bundle, contingency is to bobbin test the open tubes on both sides of the displaced batwing to locate it, then perform Plus Point testing of tubes with identified wear

• If batwing is retrievable, contingency is to re-weld the batwing to the diagonal bar using same repair plan used in RF14 38

Wrap Around Bar Inspection Contingencies (Chart I)

Gross deformation twisting of wrap around bar

• Indicated by visible twisting deformation of the wrap around bar and multiple nearby adjacent batwing cross-sections with a scuff, gouge or indentation indicating possible shroud impact. Damage would be confirmed by comparison with as-left video from RF14.

• Contingency is to bobbin test 5 open tubes per column for 5 columns on each side of the damage and Plus point identified wear. Develop and implement repair plan, such as a support attached to the wrap around bar.

39

Diagonal Tube Bundle Inspection Contingencies (Chart Ill)

Gross tube damage is identified

° Indicated by irregular tube spacing, tube dislocation, through-wall wear greater than one-third of the tube.

• Contingency is to bobbin test 5 open tubes per column closest to the damage and plus point identified wear. If stabilized tube, evaluate and determine whether needed to deplug and stabilize next tube in column to reinforce fence.

40

Gross Tube Damage Gross tube damage that could compromise fence integrity

• Tube spacing

• Force attenuation 41

Criteria For Gross Tube Damage (Assumes Failed Batwing)

Location Unacceptable Acceptable Comments BW Penetration Less Cavity Peripheral Tube Severed Than -1/3 of the way Severed Tube is Weakness in Tube through the tube Defense Line Penetrated By Batwing BW Penetration Less -1/3 of the way through the Cavity Peripheral -1/3 of the way Than -1/3,of the way tube does not result in loss of through the tube through the tube cable function.

Cavity Peripheral Total Through Tube Tube-Double Sided section Wear greater Less Than -1/3 Through This value is the summation of than -1/3 of way total Tube Wear wear on both sides of the tube through tube diameter Interior Tube From Collapsed Or Visibly No visible.distortion Collapsed Tube w/o Cable is Cavity Distorted Tube potentially unacceptable Visible Thru Wall Tube Visible Thru Wall Tube Td From InteriorInterior Tube Fm Wear than that Wr greateraterantt .Wear less than that found Unexpected wear condition Cavity found in adjacent in adjacent peripheral tube peripheral tube 42

Criteria For Gross Batwing Induced Tube Prying Action (Assumes Failed Batwing)

Location Unacceptable Acceptable Comments Tube Spacing 1/3 tube diameter criteria is developed from greater than -1/3 Tube Spacing less than 140 mil fluid force load displacement plus Cavity tube diameter -1/3 tube diameter 116 mil original gap. Adjacent batwings Caviydameer tbe -/3 ube iamter must be examined to determine if tube Peripheral between adjacent between adjacent tube expein ed t prying force Tubes tube columns columns viewed along experienced significant prying forces or if the source of the abnormal spacing is due viewed along batwing to plastic deformation of a worn adjacent batwing batwing.

Tube! Unworn Tube/ Unworn batwing This equates to about 140 mil gap plus 116 Cavity Peripheral batwing gap greater than -1.5 gap less than -1.5 times mil original gap. Nominal Tube to Batwing Pperl gatierthikne -1 . thickness of nominal Clearance is 0.026 inch (0.013 inch on each Tube times thickness of batwing side).

nominal batwing Any Location Tube To Tube (Except Col Contact At See Above This indicates that large tube displacements 84/85 in SG Vertical Tube are occurring in the SG.

32) Section Distorted batwing observed in This indicates that large tube displacements Bundle innermost portion Undistorted batwings Location Loainof p tube bundle are occurring in the SG.

43

Foreign Object Search and Retrieval Contingencies (Chart IV)

• Large mass foreign objects are present

• Indicated by visible large loose batwing segment

• Contingency is to evaluate and if needed remove the part and install a new 6" access port to retrieve using special tooling

• Loose part with new visible wear scar on an active tube

" Indicated by visual scar on an active tube and comparison with as-left video and eddy current inspection from RF14.

• Contingency is to remove accessible parts and perform Plus Point test of affected tube and surrounding open tubes to determine depth of wear scar.

44

Stay Cavity Inspection Contingencies (Chart II)

Gross tube deformation is identified 0 Indicated by irregular tube spacing, tube dislocation, through-wall wear greater than one-third of the tube.

• Contingency is to bobbin test 5 open tubes per column closest to the damage and plus point identified wear. If stabilized tube, evaluate and determine whether needed to deplug and stabilize next tube in column to reinforce fence.

• Batwing at column 84/85 cold leg has dropped

° Indicated by visual extrusion beyond the 7th eggcrate and comparison with as-left video from RF14.

• If above the ~6 th eggcrate, contingency is to ECT open adjacent tubes to locate the displaced batwing and hydraulically expand selected tubes to capture and restrain the batwing.

If below the " 6 th eggcrate, contingency is to install a new 6" access port to retrieve using special tooling.

45

No Batwing Movement No Action 46

.:Moderate. Batwing Movement

.Batwi g Stabi ization 1 ~

F-on Fo.ces -e C~t rotte *Ot--g ony F-ee F-0 PF14 positio..

As ce,-el o. grolty ,s bove p.vot pOor. ,*w-9 ShceS 01059 the contoct r-ests c,'eoteO points 0100 1ne by 06 pPtol e~gc,orte egg-otes. D-e tore.-,gth toe I oter et', F botlct 47

Large Batwin--

Access P.ort to RE 48

,Iopment

• Substantially improved tooling has been developed to facilitate contingency plans

• Batwing cutting tool is different from previously discussed

- Diamond wire mockup tests were unsuccessful

- Versatile hydraulic tool developed 49

.,.ml

-.tri e\

• 1

.~i.

4 I Delivery tool will have -150° range of motion V I .1

1 Ii A{

Multiple end effectors can be used with this delivery tool Air Gripper jf I£j .1;

1 1 50

Batwing GuttirngT

... ;."*... . * * :.. A..

Solin StayCav43ty Mbcku2p . ...

.i,.. ..**.*.

• !:.::.:& . ' . :....*i.*** I! '

. ,....*: . * ..:/* -.,!

..:... v

" *°  !:I  : i * ; * .*;

.1i*,' ..'. . ;a

::,ii *::

S i..t 7, ...

• wit * *  ::L ,*,. .*. ..:::* : *

• * ;.. .* * ,},

t

.... 4,**, 51 K.. I

Access Hoe Cons~t~raints~

This image is of the handhole showing the tubelane with the center tie rods in place The center tie rods sleeves are 1.125" and the tubelane is 4.25",

leaving 1.56" on either side I

52

0!*:;*k* ,..'. ! L .".. .

/I &-%I 1

-up*:*"i*'* Lower

...*.,/.* *.

• ,:..:**

. @f* i*.

Model showing the center stay area with stay cap and blow down Center tie rods Stay cap Blow down pipe 53

Mid-Cycle Contingencies and Criteria Summary

• Secondary inspections (Upper, Lower and FOSAR) will verify that the critical variables used for the repair plan and operational assessment are met

• The potential outcomes of each secondary inspection activity have been evaluated and appropriate contingencies planning has been taken

• A comprehensive decision flow chart has been prepared 54

Mid-Cycle Communication Plan Bob Murillo 55

SG Mid-Cycle Communication Plan

" Licensing Manager will be focal point for communications with NRC

" Pre-established communication plan

- NRR and Region IV management points of contact

• NRC Resident Inspector will be briefed daily Teleconference with NRR/Region IV, as needed

- Review of inspection results

- Review of contingency decision making

- Expansion of inspection scope

- Finding of unexpected results NRC requested photographs or video media will be made available via Licensing Manager 56

Summary and Q&A Joe Kowalewski 57

Conclusions

• Continued focus on safe operation

• Continued conservative approach to evaluation and mitigation of batwing condition utilizing defense in depth strategy

" Continue the operational monitoring, heightened awareness and conservative action limits

° Visual inspections planned for the mid-cycle outage will identify any unforeseen extent of condition or unforeseen change in the critical variables that were the basis for the repair plan and operational assessment

" Appropriate contingency actions are planned with pre-determined decision criteria to facilitate decision making for any unexpected findings.

• Communication strategy is in place for prompt information exchange 58