ML20151L820

Summary of 970715 Meeting W/Gpu Nuclear Corp in Rockville,Md Re Licensee Plans for Inspecting SG Tubing in Upcoming Refueling Outage.List of Attendees & Handouts Encl

ML20151L820
Person / Time
Site:	Three Mile Island
Issue date:	08/04/1997
From:	Buckley B NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
NUDOCS 9708070232
Download: ML20151L820 (29)

Text

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066 4 001

% / August 4, 1997 LICENSEE: GPU Nuclear Corporation FACILITY: Three Mile Island, Unit 1

SUBJECT:

SupMARY OF JULY 15, 1997, MEETING REGARDING STEAM GENERATOR TUBE REPAIR CRITERIA On July 15, 1997, the NRC staff held a meeting at the NRC offices in Rockville, Maryland, with GPU Nuclear Corporation, the. licensee for Three Mile Island, Unit 1 (TMI-1), to discuss the licensee's plans for inspecting steam generator tubing in an upcoming refueling outage. TMI-I is scheduled to shut down in September of 1997 for the 12R Outage. During the outage, the licensee will inspect and disposition steam generator tubes with indications of inside-diameter (ID) intergranular attack (IGA) degradation. The licensee previously established "below voltage criteria" (BVC) for inspecting these indications.

The focus of the meeting was to discuss the need to incorporate the licensee's BVC screening approach into the TMI-I Technical Specifications (TS) for use in the future inspections including the 12R Outage inspections. The list of meeting attendees is included in Enclosure 1. Enclosure 2 is a copy of the slides presented by the licensee at the meeting.

During the meeting, the licensee addressed three areas related to the approach for inspecting and dispositioning tubes with.BVC indications. The first topic of the presentation outlined the history of the IGA degradation that subsequently led to the establishment of a BVC classification of indications.

This discussion included the licensee's bases for concluding that BVC indications do not significantly challenge the structural and leakage integrity of the-steam generator tubing. The licensee then outlined its plans to use the BVC approach in the upcoming 12R Outage. These plans include augmenting the inspections with in-situ pressure testing of ID degradation, pulling tubes to perform burst testing, and completing condition monitoring and operational assessments to assess tube integrity over the previous cycle and the subsequent operating cycle, respectively. The licensee stated during the meeting that it would request a change to the TMI-1 TS to address this mode of degradation for the 13R Outage.

At the conclusion of the licensee's presentation, the NRC staff stated that it has concluded that a change to the TMI-I TS is necessary to implement the approach for screening BVC indications in the upcoming 12R Outage and future outages. The licensee's BVC screening approach is based primarily on a combination of indication voltage, signal-to-noise ratio and length, and

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NRC FR.E CBITER COPY 9708070232 970804 DR ADOCK 050 9 l \ f\\kk,\I

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' l degradation morphology. Inspection screening criteria based on these factors i are inconsistent with the current depth-based steam generator tube repair i limits in the TMI-1 TS. Therefore, a TS change is necessary to address this compliance issue. The staff also indicated that the licensee should consider proposing a limited amendment applicable for one cycle only given the time available for processing such an asendment prior to the 12R Outage.

Original signed by '

Bart C. Buckley, Senior Project Manager Project Directorate I-3 ,

Division of Reactor Projects - I/II  !

Office Of Nuclear Reactor Regulation Docket No. 50-289 l

Enclosures:

As stated cc w/encls: See next page l DISTRIBUTION Hard Cooy  ;

Docket File  !

PUBLIC i PDI-3 RF l OGC l ACRS l l

E-MAIL S. Collins /F. Miraglia (SJC1) (FJM)

-R. Zimmerman (RPZ)

B. Boger (BAB2) /

R. Eaton (RBEI) [ J E. Dunnington (ETD)

D. Ross (SLM3) @

B. McCabe (BCW) VTU

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C. Hehl (CWH) /

T. Sullivan (EJS)

J. Strosnider (JRS)

P. Rush (PJRI)

K. Karwoski (JKW1)

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s Three Mile Island Nuclear Station, Unit No. I cc:

Michael Ross Director, O&M, TMI Robert B. Borsum GPU Nuclear Corporation B&W Nuclear Technologies

' Suite 525 P.O. Box 480 Middletown, PA 17057 1700 Rockville Pike Rockville, MD 20852 John C. Fornicola William Dornsife, Acting Director Director, Planning and Regulatory Affairs Bureau of Radiation Protection Per.nsylvania Department of GPU Nuclear Corporation 100 Interpace Parkway Environmental Resources Parsippany, NJ 07054 P.O. Box 2063 Harrisburg, PA 17120 Jack S. Wetmore Manager, TMI Regulatory Affairs Dr. Judith Johnsrud National Energy Committee i GPU Nuclear Corporation Sierra Club P.O. Box 480 Middletown, PA 17057 433 Orlando Avenue State College, PA 16803 Ernest L. Blake, Jr., Esquire Mr. James W. Langenbach

, Shaw, Pittman, Potts & Trowbridge Vice President and Director - TMI-1 2300 N Street, NW. GPU Nuclear Corporation Washington, DC 20037 P.O. Box 480

' Middletown, PA 17057 Chairman Board of County Commissioners

of Dauphin County l l Dauphin County Courthouse Harrisburg, PA 17120 i

i Chairman Board of Supervisors 1

of Londonderry Township a R.D. #1, Geyers Church Road

Middletown, PA 17057 i

' Michele G. Evans Senior Resident Inspector (TMI-1)

U.S. Nuclear Regulatory Commission  ;

P.O. Box 311 Middletown, PA 17057 l

Regional Administrator, Region I l U.S. Nuclear Regulatory Commission l 475 Allendale Road i

King of Prussia, PA 19406 1 l

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l Attendees List '

TMI-1 Steam Generator Tube Repair Criteria Meeting July 15, 1997 i fiatiE AFFIL. j Bart Buckley NRC/NRR l

Ted Sullivan NRC/NRR/DE/EMCB Jack Strosnider NRC/NRR/DE/EMCB Phillip Rush NRR/DE/EMCB Ken Karwoski NRR/DE/EMCB l l

Scott Giacobbe GPUN  :

Rick Barley GPUN Gene Navratil GPU ,

Bob Knight GPUN S. D. Leshnoff GPUN Rich Freeman GPUN 3 David Stellfox McGraw Hill Stan Maingi PA-BRP l

ENCLOSURE 1

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! Meeting Objectiv.es

! - Strategy for Tech Spec Changes .

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) Inspection / Disposition ofBVCs:

- Refuel Outage 12R Long Term l

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- Summary ofProposed Commitments for the l 12R Outage

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Agenda l

Review BVC History Pat Walsh - Director Equipment Reliability l

Review Plans for Outage 12R (Fall 1997)

Gene Navratil -ISI Specialist Discuss Tech. Spec. Compliance Plans for Outage 12R and Thereafter l Pat Walsh - Director Equipment Reliability i

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I BVC l

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i - "Below Voltage Criteria" i

- Small Patches ofInside Diameter IGA (Verified by Tube Pulls) Resulting From the 1981 Sulfur Damage j - Too Small to -Assign Through Wall Extent Using Phase

! Angle Analysis History Supports Damage Inactive Since 1981 l

- Pulled Tubes

! - ECT History I - Absence of Unplugged Tube Leakage L

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i Characteristics of BVC i

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Inside Diameter Surface of the Tubes Not Crack-Like Volumetric

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BVCs Are Safe Because: .

- Inside Diameter IGA Volumetric Flaws Larger Than the BVCs Have Been Pulled From TMI-1 OTSGs, Examined in the Lab, and Do Not Compromise Tube Structural Integrity.

Growth Rates ofBVC Indications Have Been Essentially Zero.

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Previous BVC Analyst Guidelines

< 1.0 V (by Bobbin),* and

< 3

1 Signal-to-Noise Ratio, and

< 0.5" Cire. Extent, and 4

i I.D. Initiated

• Note that a 1.0 volt indication at TMI-1 would be a 0.4 volt indication at most other plants. (TMI-l normalizes voltage to 10 volts on the four 20%

T.W. holes.)

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t OCTAGE 12R XDE PLANS FOR

BVCs l

Applicability I.D. Initiated Flaws Non-Expanded Length of Tube

! Volumetric Nature l < 1 Volt Bobbin Coil Response

< 3 to 1 Signal to Noise Response Bobbin Voltage Normalization Set ASME Calibration Standard ECT Response from i four 20% b.D. Holes to 10 Volts Using 400 kHz

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l OLTAGE 12R XDE PLANS

FOR BVCs (cont'd) i j Data Quality Will Use Defined Bobbin Coil Probe Wear Standards i

Guidelines Will Address Data Quality i

i i Analyst Variability

. Conservatism in Rotating Probe Length & Width Sizing l Far Exceeds Analyst Variability

Bobbin Coil 1 Volt Threshold Is Very Conservative 1

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!: OCTAGE 12R NDE PLANS l:

FOR BVCs (cont'd) l Probability ofDetection @OD) l Not An Issue For Tubes With These Very i

Small Volumetric Indications Which Have l Essentially No Growth l -

NDE Technique Error l

4 Rotating Probes Oversize Length and Width j Much Larger Voltage IGA Indications Do Not

! Challenge StructuralIntegrity i.'

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4 l OCTAGE 12R XDE PLANS l

FOR BVCs (cont'd) 1 1

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Conditions Preventing Use ofBVC l Classification:

l Expansion Transitions and Expanded Regions i 400 kHz Phase Angle > 30 i

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i FLAW GROWTH RATE i

i Inside Diameter IGA Is Not Active Based

! On Degraded Tube Population

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4 Inside Diameter IGA Is Not Active Based

! On BVC Population 4

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DEGRADED TLBES i

l OOMPARISON OF STATISIICAL EVALUA110N 10 PREVIOUS EVALUATIONS Period Number Mean SID Mean SID

Indications O mnge % Deviation % Omnge Deviation i T.W. T.W. Volts Volts 1984/1986-5M 152 -2.6 6.1 -0.2 0.3 i

1986-51W1986-6R 118 +1.1 6.6 +0.0 0.2 1986-6&l988-7R 119 +2.6 5.5 +0.2 0.3 l

1988-7W1990-8R 291 -0.2 7.4 -0.3 0.4

??9 1990-8W1991-9R -2.0 7.0 +0.1 0.3 1991-9W1993-10R 207 -0.6 6.6 +0.2 0.3 1993-10W1995-11R 197 40.9 6.4 -0.3 0.4 4

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RECENT BVC HISTORY i

k Outage 9R 10R 11R j

OTSG-A OTSG-B OTSG-A OTSG-B OTSG-A OTSG-B Number ofBVC Indications Identified 195 in 122 104 in 29 141 in 90 78 in 20 151 in 95 66 in 11 During the Outage Tubes Tubes Tubes Tubes Tubes Tubes Nubmer ofNew BVC Indications 3 5 2 0 7 4 Number ofBVC Indications Also Seen In . 192 99 139 78 144 62 Previous Outages

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! Number ofPrevious Outage BVC 0 0 0 0 2 0 Indications (Never Assigned > 20% T.W.

• l and Confirmed by Pancake) " Progressing" to Degraded Status

. Number ofPrevious Outage BVC 0 0 0 0 0 0 Indications " Progressing" to Defective Mean Change (in Volts) From the Previous 0.0 V 0.0 V + 0.1 V 0.0 V -0.2 V 0.0 V Outage [ Indication Seen Both Outages]

Mean Change (in Degrees) From the - 0.4 - - 0.9

• 0.0 * +1.1* + 2.4 * - 0.5

• Previous Outage [ Indication Seen Both Outages]

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l OCTAGE 12R BVC XDE l

REPAIR PARAMETERS i

- Indications Must Be:

l I.D. Initiated, and i

l < 3:1 Signal-to-Noise Ratio, and 4

i < 1 Volt Measured Response, and

!: < 0.5" Cire. Length, and j < 0.X" Axial Length, and i Not " Crack Like" By Rotating Probe i

i OCTAGE 12R BERST/

l PRESSERE TESTS .

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l Plan to Perform In Situ Pressure Testing l During Outage 12R j -

Plan to Burst Test Pulled Tube Segment (s)

With Inside Diameter IGA l.# .

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l OCTAGE 12R 1

l EXAMINATIONS 3

i j Minimum 40% Bobbin Coil Probe ll (Including All 11R BVC Tubes)

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l Rotating Probe Examination of All 12R BVCs k

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TLBE PCLL PROGRAM j -

Plan to Pull 1 Or More Tubes With Inside Diameter IGA in Outage 12R 3

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- Previously Pulled 32 Tubes For I.D. Flaws i

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l TLBE LEAKAGE i

Current License Condition Is < 0.1 GPM

! Above Baseline i

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i Planned In Situ Pressure Testing During l Outage 12R To Confirm BVC Indications l

Will Not Leak i

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! COXDITION MONITORING OPERATIONAL ASSESSMENTS l

i l For all Degradation Mechanisms Identified, i

i Evaluate:

! As Found StructuralIntegrity, and 4

Impact On EOC Integrity i

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NRC REPORTTXG j

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Plugging Report 15 Days From Completion l ofInspection

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Tech Spec Required Outage Report to XRC l Within Agreed Upon Time Frame 4

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l TECH SPEC COMPLIANCE j

GPU Nuclear Letter Will Confirm j Commitments and Interpretations For

Outage 12R (September 1997) 4 Tech Spec Changes Will Be Put in Place for l The Xext Refueling

Outage 13R (September 1999) i i

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l Proposed Commitments Beyond Technical

! Specifications To Support Cycle 12 Operation 0

Additional BVC NDE Guidelines Axial Extent l.

Re-Confirm Morphology Characterization (Rotating Probe)

Probe Wear Evaluate NDE Variability (MRPC Sizing)

In-Situ Pressure Testing l

Tube Pulls Conditional Monitoring & Operational Assessment Post 12R Report on BVCs (Summary of all BVC Tests and Inspections)

Tech Spec Report Within Agreed Upon Timeframe Tech Spec Changes for 13R g

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