ML20202F433

Rev 1 to Technical Data Rept TDR 571 RCS Insps for IGSCC- Cycle 11R Outage

ML20202F433
Person / Time
Site:	Oyster Creek
Issue date:	03/26/1986
From:	Covill D, Demuth R, Giacobbe F GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20202F410	List: ML20202F403 ML20202F433
References
0217H, 217H, GL-84-11, TDR-571, TDR-571-R01, TDR-571-R1, NUDOCS 8607150165
Download: ML20202F433 (26)

Text

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571 g TDR NO. REVISION NO. I BUDGET 328071 1 25 TECHNICAL DATA REPORT ACTIVITY NO. PAGE OF PROJECT. Oyster Creek Nuclear ESD/ME-FA  !

Generating Station DEPARTMENT'SECTION  !

l RELEASE DATE L2-6-8fa REVISION DATE 3 26,-% l DOCUMENT TITLE.

Reactor Coolant System Inspections For IGSCC -Cycle llR Outage ORIGINATOR SIGNATURE DATE APPROVAL (S) SIGNATURE DATE l D. W. Covi11 M 7 /f 8 7' R. T. DeMuth //

l F. S. Giac d -/ [PV l l ff f l l APPROVAL FOR EXTERNAL DIS,TRIBUTION DATE l D.K.Cronebergerh , fD-k-8d.

l Does this TDR include recommendationtsP Cyes ENo if yes. TFWR/TR *

• DISTRIBUTION ABSTRACT:

) D. F., Cronemrger l Purpose

'F. S. Giacodoe l This report is GPUN's response to the NRC's Generic Letter G. E. Von .;ieca j 84-11 regarding inspections of BWR Stainless Steel Piping.

S. S. Miller i N. C. Fazaaas I This report defines the scope of inspections to be performed

)i.J.Patterson j on the reactor coolant system piping during the next sched-

.l. .i. Laggart uled outage. The purpose of the inspections is to detect the M. O. Sanfora the presence of intergranular stress corrosion cracking in D. ... Grace j stainless steel weld joints.

R. F. Wilson j

iWalt Smith-O/C Also defined are the examination criteria, repair options, lJ. L. Sullivan-O/C 4 mitigating actions, leak detection, and leakage limits.

l '. L. Lorenzo [

, SLHMARY OF KEY POINTS l l Systems to be Inspected Re ci rcula tion, reactor water cleanup, shutdown cooling, core spray, isolation condenser.

Number of Welds to be Inspected The initial sample size is approximately 75. Increased sampling is specified should cracks be detected.

l Examination Criteria Procedures and personnel will be qualified to the require-ments of IE Bulletin 83-02. Examiners will be requalified before performing examinations.

Repair Options The three repair options f or cracked welds are: 1) weld overlay, 2) spool piece replacement, and 3) system piping replacement.

Mitigating Action Mitigating actions are being considered to minimize the potential for IGSCC. The actions being cons!.dered are: 1) 8607150165 860708 induction heating stress improvement and 2) hydrogen water ADOCK 0500 9

{DR chemistry control.

I f u CNVTW PAGE ONL Y tannstr1e a.sm

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- . Rev. 1 Page la Nuclear DOCUMENT NO.

tor 5n TITLE Reactor Coolant Inspections for IGSCC - Cycle 11R Outage REV

SUMMARY

OF CHANGE APPROVAL DATE

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1 1. Changed outage identification to " Cycle llR" h sI?s/!Jt Title Para. 1.7.2 s Para. 1.1 Para. 6.2

2. Revised position on pre- and post IHSI inspections.

Para. 1.4 Para. 2.2.4 Para. 2.2.2 Para. 6.1

3. Identified examiner requalificat ion requirements.

Abstract Para. 3.2 Para. 1.5 4 Clarified IMSI evaluation basis Para. 1.7.1 Para. 6.1

5. Changed dycrogen Water Chemistry sections to reflect current status.

Para. 1.7.2 Para. 6.2

6. Para. 7.2 - Revised time period for leak rate cnange to be consistent with Tech. Spec. change

?.aquest.

7 Table I - Revised weld quantities to reflect current information.

5. Appendix B: Added statement regarding .;RC approval of weld overlays for more than one cycle.

9. Added fracture techanics analysis of flawed weldments. Para. 1.6 Para. 4.0

10. Added additional criteria for selecting welds for inspection. Para. 1.4 Para. 2.2.3.1

11. Clarified inspections of structural weld overlays in Para. 2.2.2(b). ,

12. Modified weld overlay design description ,

s c, S/e s/ic s in Para. 5.2.

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.3. L,:artfled

, ?osition regarding inspection of ' '..

Q Safo end zelds ir. TcLle I. . w.w \. s s

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r-l , . TDR NO. 571 Rev. 1 Page 2 TABLE OF CONTENTS i

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1.0 INTRODUCTION

3 2.0 SCOPE OF INSPECTIONS 7 3.0 EXAMINATION CRITERIA 11 4.0 ANALYTICAL DISPOSITION OF FLAWED WELDS 12 l 5.0 REPAIR METHODS 12 6.0 MITICATING ACTIONS 13 7.0 LEAK DETECTION AND LEAKAGE LIMITS 15

8.0 REFERENCES

17 9.0 TABLES 19 10.0 APPENDICES 21 TOTAL EFFECTIVE PAGES 25

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Page 3

1.0 INTRODUCTION

i 1.1 Purpose This document is GPUN's response to the NRC's Generic Letter 84-11,

" Inspections of BWR Stainless Steel Piping" [1].

l Augmented inspections of Reactor Coolant System (RCS) piping for intergranular stress corrosion cracking (IGSCC) will take place during the next scheduled outage (Cycle 11R). This document l

identifies the planned actions for the following:

a) Systems to be inspected b) Sampling basis for establishing the quantity of welds to be inspected for:

1. Initial inspections 2.

Additional inspections should cracks be detected during the initial examinations c' Basis for selecting specific welds for inspection d) Inspection criteria

1. Methods

2. Procedure qualification .

3. Personnel qualification e) Repair methods for cracked welds f) Mitigating actions for uncracked welds 0217H l

c-TDR No. 571 Rev. 1 Page 4 Additionally, leak detection and leakage limits are discussed.

1.2 Bac kg round IGSCC has been a recurring problem in Boiling Water Reactor (BWR) stainless steel RCS piping. It has caused numerous plant shutdowns and extensive repair / replacement programs.

The utilities, EPRI, and the NRC are involved in extensive programs for detecting and preventing IGSCC. This report addresses CPUN's planned actions for detecting and minimizing IGSCC.

1.3 Scope of Insrections Five systems are to be inspected:

1) Recirculation (5 loops)

2) Reactor water cleanup

3) Shutdown cooling

4) Core spray

5) Isolation condenser See Table I for the approximate number of welds in each system and the extent of the inspections.

These systems have been generical'y susceptible to developing IGSCC.

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TDR NO. 571 Rev. 1 Page 5 1.4 Number of Welds to be Inspected i

The initial sample size is approximately 75 welds.

The sampling basis for initial inspections is as follows:

a) 20% of the welds previously inspected (*), l a

b) 20% of the welds not previously inspected (*), and c) 100% of the weld overlays in the Isolation Condenser system.

The specific welds to be inspected will be selected based on evaluation of the following:

1) Field experience at similar plants

2) Weld history (repaired welds, shop or field welds) t

3) Carbon content l

4) Damage Index calculations

5) Previous inspection results

6) Proximity to structural weld overlays Additional sampling is required if cracks are detected. The number of additional welds is based on the system and location within the

( system.

• Note:

100% of the IHSI - treated' welds will be nondestructively examined after the treatment. The post-IdSI inspections will be the basis for compliance with Generic Letter 84-11. Pre-IHSI examinations ..

may be performed for planning purposes.

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' Rev. 1 Page 6 1.5 Examination Criteria Procedures and personnel will be qualified to the requirements of IE Bulletin 83-02 [6] and the GPUN NDE Programs Manual. In addition, examiners will be requalified to the interim guidelines established in the September 1985 NRC/BWROG/EPRI meeting.

1.6 Disposition Options Four options exist for dispositioning welds that are determined to have cracks. They are:

1) f racture mechanics,

2) weld overlay,

3) spool piece replacement, and

4) system piping replacement.

1.7 Mitigating Actions 1.7.1 Induction Heating i

Induction heating stress improvement (IHSI) is being evaluated for the systems identified above. The criteria for evaluation are:

1) field experience at similar plants,

2) the extent of weld repairs, if any, and

3) calculations, using EPRI-supplied methods, to estimate whether or not the welds are susceptible to developing ICSCC.

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. . TDR NO. 571 Rev. 1 Page 7

.7.2 Hydrogen Water Chemistry Hydrogen water chemistry control is another means of minimizing the potential for IGSCC. Full implementation in the future is currently being evaluated.

GPUN performed a limited test during the current operating cycle.

2.0 Scope of Inspections 2.1 NRC Recommendations 2.1.1 Systens to be Inspected -

The NRC, in Generic Letter 84-11, recommends performing inspections of stainless steel welds in systems, out to the second isolation valve, that are generically susceptible to developing IGSCC.

Generally, these systems are identified as having a pipe diameter of 4-inches and greater and operate at 200*F or higher. But, licensees must use field experience as part of the assessment to '

select systems for inspection.

2.1.2 Inspection Sampling The NRC recommends inspection of:

2.1.2.1 Welds not previously inspected: 20%, but not less than 4, 2.1.2.2 Welds previously inspected: 20%, but not less that 2, 2.1.2.3 All unrepaired cracked welds, i

2.1.2.4 Weld overlays where the crack length exceeded 10% of the pipe cir- l l

cumf erence, and 0217H

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, TDR E0. 571 Rev. 1 Page 8 2.1.2.5 Welds treated by induction heating stress improvement (IHSI) methods that were not post-treatment ultrasonic test accepted.

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, 2.2 GPUN Position i .

This section provides the scope of inspections that will take place l

, during the next scheduled outage. The next outage is currently l scheduled to begin in April 1986.

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i 2.2.1 Systems to be Inspected The systems and their respective piping diameter (s) are listed in Table I.

2.2.2 Inspection Sampling The sampling basis for initial inspections will be as specified in Generic Letter 84-11. The initial sample size will be approxi-mately 75 welds.

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100% of the IHSI - treated welds will be nondestructively examined af ter the treatment. The post-IHSI examinations will be the basis for ccmpliance with Generic Letter 84-11 recommendations. Pre-IHSI examinations may be performed for planning purposes.

For each pipe size 4-inches and greater in diameter in each system listed in Table I, sampling for initial inspections will be as follows:

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, . TDR NO. 571 Rev. 1 Page 9 a) Piping Welds

1. Welds previously inspected - 20% but not less than 2, and

2. Weld not previously inspected - 20% but not less than 4.

b) Weld Overlays There are 18 weld overlays on the Isolation Condenser sys-tem piping outside containment [3].

The assumption used to design the overlays was that, at each location, a through-wall crack was present for 100% of the circumference. Therefore, no credit was taken for the rema!.ning wall ligament. Each overlay will be nondestructively examined to detect relevant service-induced discontinuities. To the maximum extent possible, the outer 25% of the pipe wall beneath the overlay will be inspected.

There are no unrepaired welds with detected cracks or any welds treated with induction heating at Oyster Creek.

2.2.3 Basis for Selection of Welds This section describes the criteria to be evaluated to select specific welds for inspection.

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, . TDR NO. 571 Rev. 1 Page 10 2.2.3.1 Welds not previously inspected a) Field experience at similar plants b) Weld History

1) Field weld

2) Shop weld

2) Repair history c) Carbon content d) Damage Index Calculations (see EPRI Reports NP-2807-LD [4] and NP-2808-LD [5]). Appendix A provides a brief description of the Damage Index and its application.

e) Proximity to welds repaired with structural weld overlays (Isolation Condenser System outboard of second isolation valve).

2.2.3.2 Welds Previously Inspected "

Previous inspection results plus the criteria of 2.2.3.1.

2.2.4 Additional Inspections Should cracks be detected during the initial inspections, additional welds in the same system will be inspected. An I additional sample size equal to the initial sample size will be inspected.

If additional cracking is detected, 100% of the remaining butt welds in the system will be inspected.

This subsection does not apply to those systems on which IHSI is performed since 100% of the treated welds will be examined.

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r TDR NO. 571 Rev. 1 Page 11 The basis for these sample sizes for additional inspections can be 1

found in IE Bulletin 83-02 [6].

3.0 EXAMINATION CRITERIA 3.1 Examination Methods 4 ,

, o j The primary method of examination will be ultrasonic testing (UT).

The UT detection procedure shall have been demonstrated ef fective in accordance with IE Bulletin 83-02.

i Other NDE methods will be used, as necessary, to complement or

verify the UT findings. i i

! 3.2 Examiner Qualifications

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1 All Level II and III UT examiners will be qualified to IE Bulletin  !

l 83-02 requirements and the GPUN NDE Programs Manual. All UT i 1

examiners, including Level I, will show field performance i

capability. Operators and examiners will be requalified before performing the examinations in accordance with the interim revised

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qualification guidelines established in the NRC/BWROG/EPRI meeting I

held in September 1985. Only those individuals on the EPRI NDE Center " Registry of Qualified Individuals" will be permitted to j perform inspections.

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' TDR NO. 571 Rev. 1 Page 12 3.3 Examiner Availability GPUN does not anticipate any problems with examiner availability.

Before the next outage begins, we will have appropriate personnel i

j either hired or contracted.

i Additionally, we are investigating the use of automated equipment

] for performing the examinations. If automated equipment is used,

the number of personnel required to perform the examinations will I

be significantly reduced. - Total personnel exposure to radiation 2

will also be reduced.

i i 4.0 ANALYTICAL DISPOSITION OF FLAWED WELDS i

Indications determined to be flaws will be evaluated using fracture i

j mechanics to determine disposition of the flaws.

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5.0 REPAIR METHODS i

, This section describes the various repair options for cracked welds 1

which as a result of the analysis of section 4.0 cannot remain in service without repair.

] 5.1 Spool Piece Replacement The defective weld and adjacant piping material can be cut out of i

the system and replaced with material conforming to the latest i

] issue of NUREG-0313 [2] and current welding techniques including j Last Pass Heat Sink Welding (LPHSW) designed to reduce suscepti-i bility to IGSCC.

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TDR NO. 571 Rev. 1 Page 13 5.2 Weld Overlay Design and apply a weld overlay over the defective weld. In general, the overlay will be a Type I overlay designed to restore the full structural integrity of the weld area without taking credit for the remaining uncracked ligament of the pipe. However, each weld requiring overlay will be evaluated independently to l determine the appropriate design / application criteria; the effects of overlay (s) on the system as a whole will also be evaluated.

See Appendix B for a description of the weld overlay process.

5.3 System Piping Replacement Depending upon the extent and severity of detected cracking, com-plete system piping replacement will be considered.

6.0 MITIGATING ACTIONS This section describes the options for mitigating actions which may be implemented to minimize the occurrence of IGSCC in uncracked l

welds.

6.1 Induction Heating Stress Imprevement (IHSI)

GPUN will evaluate the following criteria to establish the systems to be treated and when:

1) Damage Index Calculations to end-of-life show a propensity for developing IGSCC, l

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l TDR NO. 571 )

Rev. 1 Page 14

2) Extent of weld repairs. Repair determination will be made by l reviewing available weld documentation and/or visual inspection of the welds,

3) Field experience at other similar plants, .

4) Outage constraints, or

5) NDE results.

Each IHSI-treated weld will be nondestructively examined after the '

treatment to ensure that no crack-like indications exist in the weld joint. Cracking detected after IHSI will be dispositioned as identified above. (Sections 4.0 and 5.0)

See Appendix C for a description of IHSI.

6.2 Hydrogen Water Chemistry Another mitigating action being evaluated by the utilities, EPRI and the NRC is hydrogen water chemistry control. Hydrogen is added to the reactor feedwater system. The hydrogen promotes the radio-l lytic recombination of hydrogen and oxygen thereby reducing the dissolved oxygen concentration. In this reducing environment (low electrochemical potential), the susceptibility to IGSCC is signifi-cantly reduced, perhaps eliminated.

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, , TDR NO. 571 Rev. L Page 15 Hydrogen water chemistry control is currently in the developmental stage. Two BWR's, Dresden 2 and Ringhals 1 (Sweden) are being used as demonstration plants to obtain operational data. Earlier test-ing at Oskarshamn II has been completed. Several BWR's have r

performed " mini-tests."

GPUN considers that there will be insufficient data available to '

support full implementation during the Cycle llR outage. But we have performed limited testing of hydrogen water chemistry during the current operating cycle. Full implementation in the future will be based on research results, industry experience, and the results of the Oyster Creek " mini-test."

7.0 LEAK DETECTION AND LEAKAGE LIMITS 7.1 Leak Detection Systems All identified leakage originating from inside the drywell, such as j f rom pump seals and valve packing, is routed to the Drywell Equipment Drain Tank. Unidentified leakage, such as from pipe cracks, flows to the drywell floor drain sump. Liquid flows by gravity to the sump. Steam will be condensed by the drywell air coolers, and the condensate is routed to the sump (7).

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There are three quantitative means of measuring the unidentified i leak rate from inside the drywell.

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, , TDR MO. 571 Rev. 1 Page 16

1. There are two drywell sump pumps. One pump will activate upon the tripping of the upper level switch in the sump. When the water level in the sump passes the lower level switch, the pump is turned off. At this time, an automatic timer starts. The timer is set such that if the upper level switch is tripped before the timer runs out, an alarm sounds in the control room i indicating an unidentified leak rate in excess of 4 gpm. The i

volume of water between the two level switches is approximately 80.5 gallons; the timer setting is approximately 20.5 minutes.

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2. The total flow f rom the sump is measured by flow meters. Every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, or less, the readout of the meters is compared to the previous reading and the difference is divided by the time interval between readings.

3. There is a level indicator in the sump. The signal from this indicator is fed to a processor in the control room which con-i tinuously displays an " instantaneous" fill rate of the sump.

There are also qualitative means available to assist in leak detection. The temperature, pressure and humidity of the drywell are continuously monitored. Any increase in these indicators will 1

be investigated to determine the cause. This may involve shutting I down the plant and entering the drywell for inspection.

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. TDR NO. 571 Rev. 1 Page 17 7.2 Leakage Limits t

When the period between sequential operations of the floor drain sump indicates a leakage rate exceeding 4 gpm, an alarm sounds in the control room. The operator will take appropriate steps to O

attempt to identify the source of the leakage. This may involve shutting down the plant and entering the drywell for inspection.

In any case, if the unidentified leakage rate exceeds 5 gpm, the plant will be shut down [8].

A Technical Specification revision was submitted to NRC to add the requirement that if there is more than a 2 gpm increase in unidentified leakage in any 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> period during steady-state power '

operation, the plant will be shut down.

The total leakage in the containment, both identified and unidenti-fled, may not exceed 25 gpm.

8.0 REFERENCES

1. " Inspections of BWR Stainless Steel Piping (Generic Letter 84-11)," USNRC, April, 19, 1984.

2. " Technical Report on .'bterial Selection and Processing Guidelines for BWR Coo'lant Pressure Boundary Piping, "NUREG-0313 Rev. 1, USNRC, July 1980. '

3. " Isolation Condenser System Piping Cracked Welds - Papair and Failure Analysis", TDR 580, GPUN, August 1984.

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TDR NO. 571 Rev. 1 Page 18

4. "IGSCC Damage Index: Application of the IGSCC Damage Model to BWR Piping and Components", EPRI NP-2807-LD, EPRI, January 1983. ,

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5. " Development of an Engineering Model for Predicting IGSCC  !

Damage - Particularly in Type-304 Stainless Steel in BWR Water Environments," NP-2808-LD, EPRI, February 1983.

6. IE Bulletin No. 83-02: " Stress Corrosion Cracking in Large -

Diameter Stainless Steel Recirculation System Piping at BWR  !

Plants", USNRC, March 4, 1983.

7. Oyster Creek FDSAR Amendment 32, Question 15.

S. Oyster Creek Technical Specification 3.3.D.

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TDR NO. 571 Rev. 1 Page 19 9.0 TABLES I. Systems to be inspected.

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TDR NO. 571 Rev. 1 Page 20 Table I Systems to be Inspected Approximate Pipe # of Welds System Size (In) I(1) 0(2) Extent Pecirculation 26 77 0 Vessel Inlets to l Vessel Outlets -5 Loops Reactor Water Cleanup 6 45 0 Between Recircula- l tion Loop and valves V-16-2 and 14 (discharge) and V-16-61 (return).

Shutdown Cooling 14 14 0 From Recirculation l Loop to dissimilar metal welds (dis-charge and return).

Core Spray 8 66 0 From Reactor Vessel l to Valves V-20-21 and 41 (South) and V-20-15 and 40 (North)

Isolation Condenser 8 0 51 (7)* Entire system ~

System (3) inside and outside drywell.

10 49 10 (1)*

12 0 51 (9)*

16 0 9 (1)*

Notes: 1) I - Inboard of the second isolation valve.

2) 0 - Outboard of the second isolation valve.

3) The number in "( )" is the number of joints with weld overlays.

4) Welds of vessel nozzle safe ends with corrosion resistant  ;

overlay cladding will not be inspected during the Cycle 11R outage; I we are investigating methods for inspecting safe end welds for implementation in a future outage. i

• Reference - NRC Isolation Condenser S.E.R.

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TDR NO. 571 Rev. I Page 21 10.0 APPENDICES A. Damage Index Calculations B. Weld Overlays C. Induction Heating Stress Improvement [IHSI).

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. TDR MO. 571 Rev. 1 Page 22 Appendix A Damage Index Calculations Damage Index calculaticns are performed to estimate whether or not a weld is susceptible to the development of IGSCC. The supporting data, including comparison of calculation results with actual cracking incidents at Dresden 2, are provided in EPRI reports NP-2807-LD (January 1983) and NP-2808-LD

( Feb rua ry 198 3 ) .

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The Damage Index calculations assess material (degree of sensitization, l material properties), environmental (oxygen content of the water) and plant operational (stresses due startups, holds; cyclic history, and time) para-1 meters in establishing the Damage Index.

The results of the calculations are then used to determine if IGSCC is like-ly or unlikely to occur.

Note that the terms "likely" and "unlikely" mean that there is a possibility that IGSCC may or may not occur. The results of Damage Index calculations cannot be taken as guarantees of whether or not a crack will develop.

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TDR NO. 571 Rev. I Page 23 Apoendix B t

Weld Overlays The weld overlay is a repair method which results in a continuous band of o

weld material deposited on the pipe surface directly over the crack. There are three types of overlay designs:

1. Type I - The overlay is designed without taking credit for the uncracked ligament of the pipe. The designer assumes a 360* through-wall crack. Thusly, tne overlay is design-ed to meet the Code requirements for structural integri-ty. Uncertainties in accurate sizing of cracks do not affect the design of the overlay.

2. Type II - The overlay is designed assuming a through-wall crack of a length equal to UT-measured length. This type of overlay is thinner than Type I since it does take credit for the uncracked pipe ligament.

This type of overlay is normally used on cracks shorter than one-half the pipe circumference.

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3. Type III - This type of overlay is used on shallow and short cracks. Credit is taken for the uncracked ligament of the pipe in both the radial and circumferential direc-tions.

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t TDR NO. 571 Rev. 1 Page 24 l Appendix B 1

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the inner portion of the pipe wall. These stresses will stop or retard crack growth. While this is an important factor in the design of Type II or III overlays, it is irrelevant to the design of Type I overlays, t

GPUN will use Type I overlays to provide structural integrity. Thusly, the accuracy of crack measurements does not enter into the design of the over-lays. And, the development of compressive residual stresses is not tech-nically necessary.

Weld overlays are currently censidered to be a short-term repair. General-ly, piping replacement, whether limited or complete, occurs during the scheduled outage following repair. However, research on the justification of continued service of overlays beyond one cycle is progressing. The NRC has approved operation with weld overlays beyond one cycle on a cycle-by-cycle case basis.

The weld overlay process has teen applied on nearly 300 weld jcints in nuclear power plants. Two plants are currently requesting approval to con-tinue operation without replacing overlayed joints.

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Appendix C

{ Induction Heating Stress Improvement (IHSI)

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l l IHSI is a treatment used on uncracked welds to change the stresses at the l l

l inner portion of the pipe wall f rom tensile to compressive. By eliminating i tensile stresses, one prevents ICSCC because, without tensile stress, IGSCC l

i cannot occur. I I

IHSI is implemented by placing an induction heating coil around the weld to be treated. Ccoling water is flowed through the pipe. The heat from the coil yields the outer surf ace in compression while the cool inside surface 4 1 l yields in tension. After cooldown, the stresses reverse, leaving the OD in i

] tension and the ID in compression. The induction coil, heat input, water i

j flow and other operating parameters are designed for each joint being treat-ed.

1 j Research to date has shown that IHSI is an effective means of mitigating 1

' IGSCC. The NRC has accepted IHSI treatments and many utilities have imple-1 i

j mented, committed to , or plan IHSI treatments in their plants. A partial listing of these plants is shown below 2

i Dresden 3 Monticello j Quad Cities i and 2 Hatch 2 a ,

j Peachbottom 2 Browns Ferry 2 and 3 1 1

] Mills tone Zimmer f Susequehanna 1 Hanford 2 I

i Duane Arnold Vermont Yankee 0217H

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