Text

Pre-Filed Hearing Exhibit NYS000392, EPRI Presentation, Steam Generator Task Force / Nuclear Regulatory Commission Biannual Meeting, (Feb. 16, 2012)
	ML12171A536
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Site:	Indian Point
Issue date:	02/16/2012
From:	; Electric Power Research Institute
To:	; Atomic Safety and Licensing Board Panel
	SECY RAS
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Steam Generator Task Force/

Nuclear Regulatory Commission Biannual Meeting February 16, 2012 NYS000392 Submitted: June 19, 2012

Agenda 8:30 am Introductions NRC/SGTF Opening Remarks - NRC/SGTF 8:45 am SGMP Steam Generator Task Force Update - SGTF 8:45 am SGMP Steam Generator Task Force Update - SGTF

SGTF Transition from NEI to EPRI SGMP

Divider Plate Cracking/Tube-to-Tubesheet Weld Cracking

Noise Monitoring

Guidance for Auto Analysis

Eddy Current Essential Variable Tolerances Eddy Current Essential Variable Tolerances

AVB Position Verification

Tube Support Plate Blockage R ti f I d t

Eff t f 600MA SG t N

M d l

Ratio of Industry Efforts for 600MA SGs to Newer Models

Top of Tubesheet Denting

Increase in Foreign Object Operating Experience 2

g j

p g

p

Agenda 11:30 am Lunch 12:30 pm SGMP Steam Generator Task Force Update (Continued) 12:30 pm SGMP Steam Generator Task Force Update (Continued)

TSTF-510

Upcoming Changes to Industry Documents

Recent SG Operating Experience

NEI 03-08 Deviations since January 1, 2011 2:30 pm NRC Discussion/Items of Interest (e g pre-service 2:30 pm NRC Discussion/Items of Interest (e.g., pre service inspection requirements, license renewal interim staff guidance) 3:00 pm Address Public Questions/Comments 3:00 pm Address Public Questions/Comments 3:30 pm Adjourn 3

SGTF Transition from NEI to EPRI SGMP

In November 2011, NEI recommended disbanding the NEI SG Task Force SG Task Force

The original purpose of the task force (development of NEI 97-06 and providing input to the Generic License Change Package) has been fullfilled Package) has been fullfilled

The EPRI SGMP and NRC discussed the future of the SGTF

- Concluded that SGTF and NRC interactions are beneficial to both organizations and should continue

EPRI SGMP will sponsor the SGTF in place of NEI EPRI SGMP will sponsor the SGTF in place of NEI

- NEI will still be a member of the SGTF 4

SGTF Transition from NEI to EPRI SGMP

The SGTF will be a working group under the SGMP Engineering

& Regulatory Technical Advisory Committee and the SGMP Integration Committee will provide oversight and support to the g

p g

pp SGTF

The SGTF will continue to meet with the NRC bi-annually

- Typically February and August

The SGTF membership will remain the same

- Jim Benson is the point of contact for the NRC

- Helen Cothron will be the SGMP Project Manager

- Jay Smith will continue to be the Utility SGTF Chair

- SGTF members will continue to include Industry, vendor and NEI representation SGTF members at large ill contin e to be the same as before the

- SGTF members at-large will continue to be the same as before the transition

Format and content of SGTF meetings with the NRC will remain unchanged 5

unchanged

End Result - Seamless transition of SGTF from NEI to SGMP

Divider Plate/Tube-to-Tubesheet Weld Project

The Generic Aging Lessons Learned Report (GALL), R2 added the divider GALLReportRevisionsUsedfor Reviewing Plant License plate and tube-to-tubesheet weld as items to be evaluated in Aging Management Plans 9%

30%

44%

ReviewingPlantLicense RenewalApplication PreGALL

Applications reviewed using R2 have required a commitment to inspect these areas once they are in the period of t

d d ti d th t

30%

17%

Rev0 Rev1 Rev2 extended operation and the steam generators have been in service more than 20 years

- Plants whose applications were reviewed using prior revisions have not made these commitments 6

Divider Plate/Tube-to-Tubesheet Weld Project

Regulatory Issue Summary (RIS) 2011-05

Highlights the addition of divider plate assemblies and tube-to-g g

p tubesheet welds to the aging management review line items

Changes the priorities of the project Date of Extended Period of Operation and SG Life > 20 Years 15 20 25 30 35 40 er of Plants N/A = Plants with 0

5 10 15 N/A 2010 2011 2012 2013 2014 2015 2016 >2016 Numb N/A Plants with no Alloy 600 material in the channel head assembly 7

License renewal reviewed under previous revisions of the GALL

Divider Plate/Tube-to-Tubesheet Weld Project

SGMP Project Plan

The immediate need is for near term inspection relief The immediate need is for near term inspection relief for the divider plate to the channel head material (carbon steel)

Solution for tube-to-tubesheet weld inspection needed in 2013

SGMP has accelerated the review of previous research on crack propagation and the development of a technical report that addresses whether cracks will a technical report that addresses whether cracks will arrest when they come into contact with materials resistant to PWSCC 8

A draft is near completion

Divider Plate/Tube-to-Tubesheet Weld Project

SGMP Project Plan Th t

h i l

t ill d t

t th t t

The technical report will demonstrate that steam generators will operate safely in the extended period of operation while the industry completes the work outlined p

y p

in the Aging Management of Alloy 600 in the Steam Generator Channel Head Assembly Roadmap Scheduled to be completed by 2016

- Scheduled to be completed by 2016 9

Noise Monitoring

The industry has developed procedures and protocol for monitoring eddy current noise to ensure an understanding monitoring eddy current noise to ensure an understanding of probability of detection

Vendors have developed software to implement noise p

p monitoring

SGMP has funded pilot projects for the last 3 years to demonstrate the procedures protocol and software demonstrate the procedures, protocol, and software

Final pilot project completed 2011

- Alloy 600MA tubing Alloy 600MA tubing

- Process and software performed as expected

- Lessons learned documented in a technical report 10

p (1022834)

Noise Monitoring

Recommendations for industry guidance will be developed in 2012 and presented to the Examination Guidelines in 2012 and presented to the Examination Guidelines Revision 8 Committee

- Revision is underway and draft scheduled by end of y

y 2012 11

Guidance for Auto Analysis

Retaking of auto analysis qualification test

- All auto systems are required to test on SGMPs auto All auto systems are required to test on SGMPs auto analysis performance demonstration database (AAPDD) and site specific performance database (SSPD)

Wh ti h

d t

When non conservative changes are made to algorithms the SSPD should be retaken

- Revision 8 subcommittee is reevaluating circumstances Revision 8 subcommittee is reevaluating circumstances when the AAPDD is to be retaken

- SGMP is evaluating the need for retaking the test when there are major revisions of the AAPDD 12

Guidance for Auto Analysis

Current Practice for Comparing Auto Analysis Results to Manual Analysis Results

- Software program does the compare

Compare criteria can be adjusted R

i 20%

d t

- Review 20% and greater

- Review all I Codes Tolerance for variance in location phase voltage

- Tolerance for variance in location, phase, voltage

- Resolution analysts determine final calls

- In addition, there is a data analysis feedback process In addition, there is a data analysis feedback process and an independent oversight process per Examination Guidelines 13

Guidance for Auto Analysis

Ongoing SGMP Auto Analysis Projects

- Comparing probability of detection for dual party analysis and Comparing probability of detection for dual party analysis and single pass auto analysis systems

- Revision 8 of the Examination Guidelines will add Appendix L to better address the latest developments in Auto Analysis to better address the latest developments in Auto Analysis, such as single party analysis

Subcommittee considered NRC feedback from auto analysis workshop

Subcommittee has submitted draft to main committee Continue development of algorithms for other damage

- Continue development of algorithms for other damage mechanisms for auto analysis

- Plan to incorporate one ANL detection algorithm into the auto l

i t lb 14

analysis toolbox

Eddy Current Essential Variable Tolerances

Development of standardized process for determining examination technique equivalency examination technique equivalency

- Objective: Develop a consistent and cost effective method to evaluate system performance, evaluate technique performance and t

d t

t b tit t t

i l

to demonstrate substitute component equivalency

Draw an equivalency between existing Examination Technique Specification Sheets (ETSS) to plant specific conditions

- Approach: Develop a process that will test for an equivalent magnetic field within the tubing as a basis for establishing equivalency between two similar yet differing acquisition setups.

Compare essential variables of EPRI ETSSs to site specific ETSSs 15

Eddy Current Essential Variable Tolerances

Technical Reports Issued

March 2008: Technical update report, Development of a Process for Determining Examination Technique Process for Determining Examination Technique Equivalency 1015126.

- Designed and produced a master set of flawed samples g

p p

that could be used to perform examination technique equivalency checks P

ti l d t

ti h

i th t th difi d

- Practical demonstration showing that the modified techniques can generate signals from selected calibration tube flaw equivalent to those generated by the qualified techniques 16

Eddy Current Essential Variable Tolerances

Technical Reports Issued

March 2009: Technical update report, Steam Generator Management Program: Development of Standardized Management Program: Development of Standardized Process for Determining Examination Technique Equivalency1018557

- Review various EPRI qualified techniques compared to field techniques with modified essential variables E

i i

t h i l j tifi ti t d b d

- Engineering technical justification - a study based on eddy current theory to justify equivalency

- Document the effect that changes in essential variables Document the effect that changes in essential variables tolerances have on the resulting eddy current signal

- Allowable tolerances were established for master set of fl 17

flaws

Eddy Current Essential Variable Tolerances

Acceptable Ranges Established for Master Set of Flaws B bbi

Bobbin:

- Raw voltage from the (4) x 20% FBHs must be >80% of qualified technique

- FBH normalized voltages within +40% of qualified technique

- FBH phase within +20° of qualified technique

MRPC:

- Raw voltage 100% Axial EDM >80% of qualified technique N

li d

lt ithi 20%

f lifi d t h i

- Normalized voltages within +20% of qualified technique

- EDM notch phase within +10° of qualified technique 18

Eddy Current Essential Variable Tolerances

Technical Reports Issued S

t b

2010 Fi l

t St G

t

September 2010: Final report, Steam Generator Management Program: Development of Documentation for Examination Technique Equivalencies1020992.

q q

- Additional field data were compared to the EPRI ETSS data f

- Additional data were collected using the master set of calibration standards produced in the first phase

- Additional data documenting the effect that changes in Additional data documenting the effect that changes in essential variables tolerances have on the resulting eddy-current signal 19

Eddy Current Essential Variable Tolerances

Acceptance Ranges M th d l

Methodology

- Technique should be considered equivalent If all compared flaws are within the acceptance range compared flaws are within the acceptance range

- Technique is NOT equivalent if only the normalization flaw is within range; resolution is required

- If some compared indications are outside the acceptance range, evaluate those flaw responses and document the reason for the difference and document the reason for the difference 20

Eddy Current Essential Variable Tolerances

Revision 8 of the PWR SG Examination Guidelines Alt t

M th d f B bbi P

b d R t ti P

b

Alternate Method for Bobbin Probe and Rotating Probe Techniques for drawing equivalency

- Appendix H will include acceptable ranges Appendix H will include acceptable ranges

- Include a reference to the three Technical Reports

- Contractors responsible for the three Technical Reports will be asked to participate in the effort to incorporate the findings of this project into the new guidelines guidelines 21

AVB Position Verification

Meeting February 14, 2012

- Westinghouse

- AREVA

- MHI Babcock and Wilcox

- Babcock and Wilcox

- EPRI

- Utility representatives Utility representatives

Reviewed North Anna and Mihama events and causal factors

Discussed position verification techniques and manufacturing improvements in the mid 80s

Results from the meeting will be evaluated by the E&R TAC 22

Results from the meeting will be evaluated by the E&R TAC

Tube Support Plate Blockage

During the June 2011 Executive Materials Meeting it was t d th t SGTF id t t f t b f

li requested that SGTF provide status of tube fouling projects to the NRC technical staff

SGMP Project Dynamic Analysis of a Steam Generator j

y y

(2009-2013)

Develop a steam generator dynamic simulation model to evaluate the effect of deposit accumulation at tube support evaluate the effect of deposit accumulation at tube support plates on steam generator water level stability

Benefits

Assessment of tube support plate deposit loading on operational parameters (water level oscillations) for several steam generator designs 23

several steam generator designs

Tube Support Plate Blockage

SGMP Project Prediction of SG TSP Flow Blockages (2010-2012)

Develop a model to predict the blockage of broached-hole openings in topmost SG TSPs

Benefits Benefits

Quantify the probability that a plant will experience a certain level of TSP blockage during future operation

Reduce the uncertainty in the estimated time necessary to reach utility-defined TSP blockage levels 24

Ratio of SGMP Projects for Alloy 600MA Tubing to More Advanced Materials

During the June 2011 Executive Materials Meeting it was requested that SGTF provide the ratio of industry effort for to More Advanced Materials requested that SGTF provide the ratio of industry effort for Alloy 600MA SGs to that for the newer/replacement SGs to the NRC technical staff

- Approximately 90% of SGMP effort is applicable to both original Alloy 600MA SGs and newer/replacement SGs with Alloy 600TT and Alloy 690TT tubing with Alloy 600TT and Alloy 690TT tubing

- About 10% of effort is focused on newer/replacement SGs only 25

Top of Tubesheet Denting

Plant Experience

Denting at the top of the tubesheet has occurred in 1 domestic (Alloy 690) and 10 foreign plants (worldwide) domestic (Alloy 690) and 10 foreign plants (worldwide)

3 (Alloy 800 and Alloy 600TT) of the 11 plants have SCC indications at dents

Denting is associated with a hard sludge pile

SGMP Project Top of Tubesheet Denting (2010-2014)

Review plant experience, materials of construction, chemistry Literature review of low alloy steel corrosion

Literature review of low alloy steel corrosion

Finite element analysis using typical dent 3-D profile 26

Top of Tubesheet Denting

Benefits

Identify plant operating conditions and maintenance practices that lead to top of tubesheet denting practices that lead to top of tubesheet denting

Investigate the extent to which potential mitigation methods would be expected to reduce the risk of SCC p

If needed, update secondary water chemistry guidelines 27

Foreign Object Task Force Update

During the December 2011 EPRI Drop in Meeting it was requested that SGTF provide status of foreign object trends

A small industry group was formed June 2011 to update foreign object trend data that was first published in 2005 Th 2005 t

th lt f

i d t

ff t t

The 2005 report was the result of an industry effort to study what was considered an adverse trend in foreign object events between 2002 and 2005 and resulted in j

the following SGMP actions

- Several SGMP projects were funded for foreign object detection sizing and analysis object detection, sizing, and analysis

- Additional guidance was added to the Integrity Assessment Guidelines 28

- Foreign Object Handbook was published

Foreign Object Task Force Update

The objectives of the current task force is to determine:

- If there is an increasing trend in tube wear caused by foreign g

y g

objects since 2005

- The specific causes of the loose parts wear events that have occurred since 2005 occurred since 2005.

Have the causes changed

- If there is a correlation between plants that skip p

p inspection and plants that have problems with foreign objects (frequency and severity)

If there is a correlation bet een the plant design and the

- If there is a correlation between the plant design and the number of foreign object events

- The status of projects that were recommended by the 29

p j

y 2005 task force.

Foreign Object Task Force - 2005 Report Conclusions are Unchanged Conclusions are Unchanged

No leakage caused by foreign objects since 2005 N

t b d b f i

bj t h d d

No tube wear caused by foreign objects have exceeded performance criteria

Quantity of reported foreign objects increased 2002 to 2005 Quantity of reported foreign objects increased 2002 to 2005 and remains steady

- Plants performing exams in areas that have never been f

(

)

inspected before (preheater inspections)

- Heightened awareness 30

TSTF-510 Planned Submittals

From the 2011 survey Plan to Submit Plan to Submit Within 3 Months of Plan to Submit Within 6 Months of Plan to Submit Within 1 year of Plan to Submit More than 1 year of No Plan to Submit ASAP Months of NOA Months of NOA year of NOA year of NOA No Plan to Submit Number of Plants 1

6 3

33 18 1

Number of LARs*

1 2

2 16 11 1

A d

l it d i t l

t h T

h S

Assumes dual unit and sister plants have common Tech Specs Notice of availability was issued October 2011 31

TSTF-510 Planned Submittals

Update

- Byron/Braidwood-1/2 -March 30, 2012

- TMI March 30, 2012

- Wolf Creek - April 26, 2012 Turkey Point 3/4 Spring 2012

- Turkey Point 3/4 - Spring 2012

- Prairie Island-1/2 - Summer 2012

- North Anna 1/2 - Summer 2012 North Anna 1/2 Summer 2012

- ANO-1/2 - before October 2012 32

TSTF-510 Issue

Paragraph d.2 for all the material types, the Traveler states:

"If a degradation assessment indicates the potential for a type of d

d i

l i

i l i d

i h degradation to occur at a location not previously inspected with a technique capable of detecting this type of degradation at this location and that may satisfy the applicable tube repair criteria, the minimum number of locations inspected with such a capable i

ti t

h i d

i th i d f th i

ti i d inspection technique during the remainder of the inspection period may be prorated.

The issue is that tube repair criteria should have been changed to tube plugging [or repair] criteria to match the changed to tube plugging [or repair] criteria to match the rest of the wording in TSTF-510.

The NEI TSTF and NRC met on Feb 15 and the following was discussed as resolution:

was discussed as resolution:

- NEI TSTF to send letter to NRC stating that paragraph d.2 is in error and the fix is an administrative change to change the wording 33

- NRC will respond with an acceptance letter stating that the change is not a technical change and TSTF 510 will still fall under CLIIP process

SGMP Industry Document Status and Revision Schedule and Revision Schedule GuidelineTitle Current Rev#

Report#

Last Pub D t Imple mentation D t ( )

Interim Guidance Review Date Comments Date Date(s)

SteamGenerator Integrity Assessment G id li 3

1019038 Nov 2009 9/1/10 SGMP IG1001 2012 Guidelines EPRISteam GeneratorInSitu PressureTest G id li 3

1014983 Aug 2007 3/14/08 6/14/08 None Rev4in progress Guidelines PWRSteam Generator Examination G id li 7

1013706 Oct 2007 9/1/08 SGMP IG0804 Rev8in progress Guidelines PWRSteam GeneratorPrimary toSecondary L

k G id li 4

1022832 Sept.

2011 4/11/2012 7/11/2012 None 2013 34

LeakageGuidelines

SGMP Industry Document Status and Revision Schedule and Revision Schedule GuidelineTitle Current Rev#

Report#

Last Pub Imple mentation Interim Guidance Review Date Comments Date Date(s)

PWRPrimary WaterChemistry Guidelines 6

1014986 Dec 2007 6/17/08 9/17/08 SGMP IG0901 SGMP ReviewBoard Interpretation CHEM18issued IG1102 Rev7willbegin 2012 PWRSecondary WaterChemistry 7

1016555 Feb 2009 8/20/09 11/20/09 None 2012 y

Guidelines

/

SteamGenerator Management Program 3

1022343 Dec 2010 9/1/11 12/31/11 None N/A g

Administrative Procedures SteamGenerator Degradation 1

1019037 Dec 2009 N/A None N/A 35

g SpecificFlaw Handbook

Operating Experience - Alloy 690TT Tubing

46 units in the US with 690TT tubing

43 have conducted the first in-service inspection p

Date of first in-service inspection 1990 - 2011

Some plants have experienced a large number of indications in the first inservice inspection

Some have experienced a large growth in numbers of indications in subsequent inspection indications in subsequent inspection 36

690TT Units Affected by Wear MECHANISM NUMBER OF DOMESTIC UNITS AFFECTED Foreign Object Wear 12 U-Bend Support Wear 20 Support Structure Wear 31 T b T b W

2 Tube-to-Tube Wear 2

Data from Steam Generator Degradation Database as of December 2011 37

690TT Plants Affected by Wear

Because of the large number of indications and/or growth rates some plants are not able to skip primary inspections rates, some plants are not able to skip primary inspections

Diagnostic examinations have been performed to verify the characteristics of wear indications

- Wear can be flat or tapered, single or double sided 38

Increase in U-Bend Support Wear in Replacement SGs Replacement SGs

A plant with replacement SGs with A690TT tubing experienced an increase in U-Bend support tube wear p

pp during a recent SG inspection

During the previous inspection in 2006, ~50 indications of U-Bend support tube wear were detected with a 50%

pp inspection

During the 2011 SG inspection, the number of indications increased to ~2000 indications during a 100% inspection

Condition Monitoring performance criteria were met

Utility conducting root cause 39

Tube-to-Tube Wear

Tube-to-tube wear reported by two plants during fall 2011 SG inspections Details were presented to the NRC January 26 2012 (ADAMS

Details were presented to the NRC January 26, 2012 (ADAMS Accession No. ML120270416)

SGMP initiated project 2012 to develop tube-to-tube wear p

j p

ETSSs

Root cause in progress

SGMP committees reviewed the initial OE and determined that no immediate changes to guidance is necessary Wh t

i f ti i

id d t SGMP itt

When root cause information is provided to SGMP, committees will reevaluate the need to enhance guidance 40

Operating Experience - Alloy 600TT Tubing

Plants are still using temporary alternate repair criteria to li it i ti i

th t b h

t limit inspections in the tubesheet

Cracking continues to be identified in Alloy 600TT tubing Axial Circ Axial Circ Location ODSCC PWSCC UBend X

TSP/FDB X

TTS/ExpTrans X

X X

X Tubesheet X

X Tube End X

X 41

TubeEnd X

X Removed X from Tubesheet ODSCC based on SGDD December 2011

Tube End Welds

Impact marks identified on tube-to-tubesheet welds tube to tubesheet welds with bowl camera

Marks have been there since 1989/91 time frame since 1989/91 time frame 42

Tube End Welds

High resolution and H* cameras were used to evaluate th diti f th ld the condition of the welds 43

Tube End Welds

Acceptance criteria was developed by OEM

- Based on ASME Section III, design specification, NSSS design transients for extended power uprate, and stress report report

- Structural criteria based on number of impacts to weld

- Leakage criteria based on loss of continuity at weld

- Leakage criteria based on loss of continuity at weld interface

- A team of OEM engineers evaluated every tube to g

y tubesheet weld in SG B hot leg

All tube to tubesheet welds passed, no tubes required 44

plugging

August 2011 Earthquake

US utility experienced an earthquake greater than operating basis earthquake

Both units required to perform steam generator inspections by Section 3.10 of Examination Guidelines R

i t t f

i ti d

i l

t h td

Requirement to perform inspections during plant shutdown subsequent to any of the following conditions:

- SG Primary-to-secondary leakage leading to plant SG Primary to secondary leakage leading to plant shutdown

- Seismic occurrence greater than the Operating Basis E

th k

Earthquake

- Loss-of-coolant accident requiring actuation of the engineered safeguards 45

engineered safeguards

- Main steam line or feedwater line break

August 2011 Earthquake

Steam generator eddy current and visual inspections were f

d b th it performed on both units

No damage identified

Both units back on line

Both units back on line 46

August 2011 Earthquake - Basis for the Requirement Requirement

The forced outage guidance in the current revision of the Examination Guideline was based on item 6.e. of Regulatory Guide 1.83, Revision 1, July 1975

Typical plant Tech Specs (TS 5.5.9) also had these i

t til th d l t d t

f requirements until they were deleted as part of implementation of performance based inspection requirements in TSTF-449 Revision 4 (or equivalent) q

(

q

)

The change of Tech Specs was required by NRC Generic Letter 2006-01, and the NRC subsequently withdrew Regulatory Guide 1.83

The steam generator Tech Specs are now performance based with a requirement to maintain tube integrity and 47

based with a requirement to maintain tube integrity and meet structural and leakage performance criteria

August 2011 Earthquake - Future Modification of Requirement Requirement

Revision 8 of the Examination Guidelines will delete this prescriptive requirement prescriptive requirement

Interim guidance will be developed to add a performance based requirement to the Integrity Assessment Guidelines based requirement to the Integrity Assessment Guidelines for the following events:

- SG Primary-to-secondary leakage leading to plant shutdown

- Seismic occurrence

- Loss-of-coolant accident requiring actuation of the engineered safeguards 48

- Main steam line or feedwater line break

Tie Rod Bowing

Once through steam t

id tifi d generator identified new tie rod bowing

- SGA tie rod bowing

- SGA tie rod bowing remained the same (12)

- Identified tie rod bowing in SGB for the first time (7) first time (7)

- No tube wear associated with tie rod 49

assoc a ed e od bowing

In Situ Pressure Tests Since Last Meeting

One US plant performed 3 full tube in situ pressure tests May 2011 May 2011

- One indication exceeded leakage screen

- PWSCC U-Bend axial indication at H07+10.4, 1.37 PWSCC U Bend axial indication at H07 10.4, 1.37 volts

- Two tubes were tested preventively due to permeability variation

- Tests were run up to and including 3dP No leakage during tests

- No leakage during tests 50

Westinghouse Nuclear Safety Advisory Letter (NSAL-12-01)

(NSAL 12 01)

Issued January 5, 2012 A f i

tilit t d b t l d d ti i

th

A foreign utility reported base metal degradation in the primary channel head in one of three steam generators

Unit has been in operation since 1987 and the condition Unit has been in operation since 1987 and the condition was noticed in Fall 2011

The area of degradation was in bottom of the channel head near the center bowl drain and divider plate

The visually observed degradation is located only in one SG and only on the cold leg side of the channel head in SG, and only on the cold leg side of the channel head in the vicinity of the central drain line 51

Westinghouse Nuclear Safety Advisory Letter (NSAL-12-01)

(NSAL 12 01)

The largest defect in the cladding is 7.7 mm (0.3 inch) x 14 4 mm (0 6 inch) by ultrasonic examination 14.4 mm (0.6 inch) by ultrasonic examination

There are five other smaller observed defects in the cladding in the region of the drain line g

g

The degradation in the channel head base metal is a volumetric loss in the form of one large cavity which extends to a maximum depth of 28 mm (1 1 inches) extends to a maximum depth of 28 mm (1.1 inches)

The area of the degradation in the base metal is irregular in shape and extends a maximum of 75 mm (3.0 inches) from p

(

)

the edge of the drain line, with a maximum azimuthal extent of 285° about the central drain 52

Sketch of the Channel Head Base Metal Cavity Geometry and Size Geometry and Size 53

Westinghouse Nuclear Safety Advisory Letter (NSAL-12-01)

(NSAL 12 01)

The cause of the cladding degradation is not currently known and may have been an isolated occurrence known and may have been an isolated occurrence

There has been no other reported degradation or cladding issues in this part of the SG in other SGs p

Recommendations

Perform a visual inspection using bowl cameras with dry SG condition the next time primary manways are open condition the next time primary manways are open

Inspect the channel head cladding, divider plate-to-channel head weld, and when accessible, the weld at the top of the channel head bowl drain tube within the mouse hole channel head bowl drain tube within the mouse hole

The inspection can be limited to the approximate area included within a 914 mm (36 inch) radius centered on the very bottom of the channel head bo l 54

of the channel head bowl.

Inspecting for gross defects

Westinghouse Nuclear Safety Advisory Letter (NSAL-12-01)

(NSAL 12 01)

If no degradation is detected during the initial visual inspections document the inspection results and continue inspections, document the inspection results and continue this inspection each time primary manways are open

If degradation is detected g

If the inside surface of the channel head has been machined smooth, use dye penetrant test to establish extent of degradation extent of degradation

Use UT from outside of the steam generator to determine if any wastage of the channel head base y

g material has occurred

Perform engineering assessment 55

Westinghouse Nuclear Safety Advisory Letter (NSAL-12-01)

(NSAL 12 01)

Westinghouse analysis justified another cycle of operation for the foreign plant as there was sufficient base metal for the foreign plant as there was sufficient base metal remaining

An E&R TAC/Westinghouse phone call took place on g

p p

1/11/2012

- SGMP has disseminated the NSAL to all utilities regardless of SG manufacturer regardless of SG manufacturer

- Bowl cameras that are currently used for bowl scans should be adequate to look for similar issues q

- Utilities should treat the NSAL as Operating Experience and address it in either their corrective action program or th i D d ti A

t 56

their Degradation Assessments

NEI 03-08 Deviations

Two permanent deviations St G

t E

i ti G id li R7

- Steam Generator Examination Guidelines, R7

- Single pass auto analysis Steam Generator Secondary Water Chemistry

- Steam Generator Secondary Water Chemistry Guidelines, R7

- Wet lay up steam generator sample frequency

Two short term deviations

- Steam Generator Examination Guidelines, R7

- PSI prior to hydro

- Steam Generator Secondary Water Chemistry Guidelines R7 57

Guidelines, R7

- Wet lay up steam generator sample frequency

NRC Slides 58

EP121 I ELECTRIC POWER RESEARCH INSTITUTE

Address Public Questions/Comments 59

EP121 I ELECTRIC POWER RESEARCH INSTITUTE

ADJOURN 60

EP121 I ELECTRIC POWER RESEARCH INSTITUTE

Together Shaping the Future of Electricity TogetherShaping the Future of Electricity 61

ML12171A536

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