ML20059G792

Summary of 930929 Meeting W/Util Re Repair Method Which Will Submit for NRC Review & Approval.List of Attendees Encl

ML20059G792
Person / Time
Site:	Calvert Cliffs
Issue date:	10/29/1993
From:	Mcdonald D Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 9311090091
Download: ML20059G792 (17)

Text

2 .

fM%q i 4 . [ t UNITED STATES

[ kj j NUCLEAR REGULATORY COMMISSION  :

(yh j WASHINGTON. D C. 20555-0001 l

'$ ./ October 29, 1993 L

1 Docket Nos. 50-317  !

and 50-318 i

LICENSEE: Baltimore Gas and Electric Company (BG&E)

FACIlllY: Calvert Cliffs Nuclear Power Plant, Unit Nos. I and 2

SUBJECT:

MEETING

SUMMARY

REGARDING THE SEPTEMBER 29, 1993, MEETING T0 s i

DISCUSS A PROPOSED APPROACH FOR ROLL TYPE REPAIRS ON PRESSURIZER I

HEATER PENETRATIONS BACKGROUND The Calvert Cliffs, Units 1 and 2, pressurizer penetrations are fabricated from Inconel Alloy 600 material which is susceptible to primary water stress corrosion cracking (PWSCC). In 1989 reactor coolant leakage was discovered on 20 heater penetrations and one pressure / level penetration in the Unit 2 pressurizer. BG&E requested that the staff approve the use of Inconel Alloy 590 material for the replacement of Units I and 2 pressurizer penetrations as an alternative to the continued use of Inconel Alloy 600.

Inconel Alloy 690 was chosen as a preferred material because it's mechanical properties are equivalent to Inconel Alloy 600, but is less susceptible to

, PWSCC. The staff approved the request and the Unit 2 pressurizer penetrations

were replaced.

The Unit 1 pressurizer penetrations have not been replaced and are Inconel l Alloy 600. The Unit 1 pressurizer penetrations were inspected when the Unit 2 l problem occurred and no leakage was found. The leakage at the Unit 2  !

penetrations was not only the result of Inconel Alloy 600 being susceptible to l PWSCC but was also related to the effects of some previous work which had been '

performed on the Unit 2 pressurizer penetrations.

BG&E plans to inspect the Unit 1 pressurizer heater penetrations during the I unit's upcoming refueling outage in the spring of 1994. Although there has been no indication of leaks or problems, BG&E wants to have an approved repair method in case some unforeseen problems are identified during the upcoming ,

inspection. BG&E plans to submit, for NRC review and approval, a proposed repair method which utilizes a roll / plug type of process for repairing any pressurizer penetrations where leakage is found.

PURPOSE The subject meeting was held to discuss the repair method which BG&E will submit for the NRC staff's review and approval. A list of attendees and a f p

nonproprietary version of the BG&E presentation are enclosed.

A 020103 9a22o90o91 9aso29 PDR NP4 Ri.E CENTER COPY P

ADOCK 05000317 PDR

i October 29, 1993 1

SUMMARY

BG&E and its contractor, MPR Associates, Inc., provided the presentation which is outlined in an enclosure to this sumary. The background and purpose for the meeting, as discussed above, was shortened due to the time limitations on the availability of some of the attendees. A major portion of the meeting which discussed in detail the proposed repair method, which utilizes a rolling l process and expansion plugs, was proprietary.

Details of the repair process, the qualification of the repair process, examinations which will be performed on the penetrations prior to performing repairs, requirements for ensuring adequate repairs, method to prevent repaired penetration ejection, and details of the unreviewed safety question evaluation were discussed. The analysis performed in support of the proposed repair method included consideration for normal operation, accident conditions, and transients. It was noted that the proposed repair process should result in no degradation to the pressurizer because the repairs result in secondary vessel stress without permanent deformation and no resultant metallurgical effects on the pressurizer.

An overall summary of the presentation is included in the enclosed outline.

The NRC staff identified three items for BG&E to further consider prior to making its submittal. The first item was related to the acceptance criteria for continued service as it relates to the current technical specifications ,

requirement of no primary pressure boundary leakage. The second item was a i request that any additional test related data or information related to crevice corrosion of Inconel Alloy 690 be provided. Finally, it was noted that there appeared to be interest in the proposed repair process by other utilities and, if this is the case, the proposed request should be submitted as a lead plant due to the potential generic use.

m_

Daniel G. Mcdonald, Sen or Project Manager Project Directorate I-l Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation

Enclosures:

1. Attendees

2. Presentation Outline cc w/ enclosures: ,

See next page j l

e F

t

a ,

1 .

l l

1 Calvert Cliffs Nuclear Power Plant l Baltimore Gas & Electric Company Unit Nos. I and 2 i l

cc Mr. Michael Moore, President Mr. Joseph H. Walter s Calvert County Board of Engineering Division Comissioners Public Service Comission of 175 Main Street Maryland

Prince Frederick, Maryland 20678 American Building 231 E. Baltimore Street D. A. Brune, Esquire Baltimore, Maryland 21202-3486

General Counsel

Baltimore Gas and Electric Company Kristen A. Burger, Esquire P.O. Box 1475 Maryland People's Counsel Baltimore, Maryland 21203 American Building, 9th Floor 231 E. Baltimore Street Jay E. Silberg, Esquire Baltimore, Maryland 21202 Shaw, Pittman, Potts and Trowbridge 2300 N Street, NW Patricia T. Birnie, Esquire Washington, DC 20037 Co-Director Maryland Safe Energy Coalition Mr. G. L. Detter, Director, NRM P.O. Box 33111 Calvert Cliffs Nuclear Power Plant Baltimore, Maryland 21218 4

1650 Calvert Cliffs Parkway Lusby, Maryland 20657-4702 Mr. Robert E. Denton 4

Vice President - Nuclear Energy 1 Resident Inspector Baltimore Gas and Electric Company c/o U.S. Nuclear Regulatory Calvert Cliffs Nuclear Power Plant  !

! Comission 1650 Calvert Cliffs Parkway  !

j P.O. Box 287 Lusby, Maryland 20657-4702 St. Leonard, Maryland 20685 Mr. Richard I. McLean

Administrator - Radioecology Department of Natural Resources 580 Taylor Avenue Tawes State Office Building B3 j Annapolis, Maryland 21401 4

Regional Administrator, Region I l U.S. Nuclear Regulatory Comission 475 Allendale Road King of Prussia, Pennsylvania 19406 l

1 i 4

l

4 DISTRIBUTION LIST FOR MEETING

SUMMARY

OF 09/29/93

• w/ handouts

• Docket File NRC & Local PDRs

• PDI-l Reading T. Murley/F. Miraglia,12/G/18 J. Partlow, 12/G/18 S. Varga J. Calvo R. A. Capra

• D. Mcdonald C. Vogan OGC E. Jordan, MNBB 3701 W. Koo, 7/D/4 R. Hermann, 7/D/4 ACRS (10)

V. McCree, EDO, 17/G/21

• C. Cowgill, Region I cc: Licensee & Service List

ENCLOSURE 1 September 29. 1993 l l

Proposed Acoroach For Roll Tvoe l Repairs On Pressurizer Heater ,

Penetrations Meetino l List of Attendees i i

l Participants Oraanization i Daniel Mcdonald NRC/NRR/DRP/PDI-I j Robert A. Capra NRC/NRR/DRP/PDI-1 William H. Koo NRC/NRR/DE/EMCB i Robert A. Hermann NRC/NRR/DE/EMCB  !

Joe Richards BG&E I Getachew Tesfaye BG&E Bernie Rudell BG&E Bruce Montgomery BG&E Jeffrey C. Pochler BGLE Joselito 0. Calle BG&E

, Robert O. Hardies BG&E Noman Cole MPR Associate ]

Sterling Weems MPR Associate William McCurdy MPR Associate Bob Borsum B&W Nuclear Technologies Kirsten Burger MD Office People's Counsel l

l I

I l

i l

i l

_ _ . . _ , _ . . , . _ _ _ . _ _ _ _ . . _ , . , _ . . . . . ~ . _ . _ , . _ . , . . . , _ , . . . . . , , , . . . . _ . . . . , . , _ _ , , . . _ , ,

l Escwsunt 2 l

CALVERT CLIFFS PRESSURIZER ROLL AND PLUG REPAIRS FOR INCONEL 600 WELDED SLEEVE TYPE NOZZLES

Introduction:

J. Richards Technical Presentation: S. Weems l

l Baltimore Gas and Electric Company September 29,1993 ,

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I OUTLINE OF TECHNICAL PRESENTATION 1

1. Background on Cracking and Repairs of Sleeve Type )

Nozzles  !

i l

• Type of Nozzles Leakage Path Previous Roll Repairs of Sleeve Type Nozzles Key features

2. Calvert Cliffs inconel 600 Pressurizer Sleeve Type Nozzles Present Status Repair Designs Roll Repair of Instrument Nozzle l

Roll / Plug Repair of Heater Sleeve l

Qualification of Repairs l

Mockup Tests l

Analyses l

l Examinations before Repair ,

l -

Repair Inspection Requirements for Leakage  !

3. Summary l

l l__ __ _ __ - . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . . _ _ . _ _ __ . - - . _ . . - . - _ _ . . -

Full Penetration Wcld

/ M -

/

. - 1. Integral Forging Nozzle

.- Seal and Retaining Weld

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2. Sleeve Type Nozzle e

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MPR ASSOC:ATES -

F-90~84-31 ]

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Existing Weld Sutter

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/ 'Ty;ical 1.ccation Of

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In-Sewice Induced

/'I Stress Corresten

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g Ty;ical L.eak Fath With Cracked Steeve Steeve

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l (9 Note: Only One Cf Several Different Weld Configuratiens Used is Shcwn AbcVe.

. TYPICAL CRACK LOCATION IN EXISTING DESIGN WELDED _ SLEEVE TYPE NOZZLE (9 FIGURE 2

ROLL REPAIR EXPERIENCE l l

l l

- BWR Reactor Vessel Sleeve Type Nozzles l Repairs I f

l l

Number of Size of Date of Nozzles Sleeve Type Plant Repair Repaired Nozzle -

Oyster Creek 1974 1 2" OD Nozzle  !

Big Rock 1979 1 5.2" OD Nozzle Point _.

NMP-1 1984-1993 25 6" OD Nozzle Experience -- Excellent

- NRC approved--per safety evaluations (and per 10CFR50.55a(a)(3) for NMP-1).

i

. j 7/32' Thk -

Field Weld; Clad

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71/8" Thk '

l Bottom Head i Reactor Vessel ,

2.00' O.D.

I Incore Instrurnent Sleeve Nozzle

- 1.375" 1.D.

BWR Incore Instrument Sleeve Nozzle 1 F424644

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l 304 SS Weld / /

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Weld l

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24 ss Cladding

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NY / / j Carbon Steel  !

Vessel /) , _ , i jN l

'/ Roll Repair Area

1. y / x4 ss ,

CRDM Housing

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_qRD PENETRABON CONFIGURABON

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ANALYSES

• Normal Operation Accident Transients Tendency to Loosen Joint Fatigue J

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- - . . . _ . . , . - , - . . . - -,.y-. . .,,, ,#, , , ., ,_., , - . ,

't NO STRUCTURAL DEGRADATION OF VESSEL AFTER REPAlR Stress corrosion cracking will not occur in vessel P3 material (based on experience).

Fatigue crack growth will not propagate into vessel P3 material (based on experience and calculations).

No significant general corrosion of vessel (per analysis and experience).

Roll / plug repairs result only in secondary vessel stress without permanent deformation (based on analysis and mockup tests).

No metallurgical effects on vessel.

-...-- , , m.-- v=m. - , . . .r. . . - -m-.- , -._

i EXAMINATIONS BEFORE REPAIR

- Surface examinations to ensure sleeve nozzle cracking is as expected.

• Visual examinations to ensure no significant vessel damage (due to erosion / corrosion).

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,, . . - . _ . _ , , _ , , _ _ . . , . . _ _ , ,. . _ . ,___,.,.e . ._m , ,. ., . . , .,-.

i LEAKAGE INSPECTION REQUIREMENTS FOR REPAIRED JOINTS l

• Visual inspection (with insulation removed as needed) i 1

- Boric acid deposits.

Iron oxide stains.

Water dripping. ,

1 Frequency During hydrostatic test after repair (before plant is operated).

During shutdowns per existing plant requirements.

]

Acceptance criteria for continued service (virtually no leakage allowable).

Maximum of 0.1 cubic inch of boric acid deposit per inspection interval.

Maximum of one drop of water every 10 minutes.

4 4

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5

SUMMARY

e

• Stress corrosion cracking (root cause) is well understood

and poses no threat to the vessel.

• The basic roll repair approach for pressurizer sleeve type

! nozzles at CCNPP has been previously accepted and

applied in the field (i.e., a historical precedent is available).

• Repair quality obtained by use of appropriately conservative safety factors and rigorous testing.

Repair safety enhanced by redundant retention features.

This repair reduces personnel exposure, outage time, and cost as demonstrated by previous applications.

BG&E will submit a request for NRC authorization for these roll / plug repairs per 10CFR50.55a(a)(3)(1) for possible use d

in the 1994 refueling outage.

.n I s

I 1

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October 29, 1993

SUMMARY

l BG&E and its contractor, MPR Associates, Inc., provided the presentation which ,

is outlined in an enclosure to this summary. The background and purpose for )

the meeting, as discussed above, was shortened due to the time limitations on  !

the availability of some of the attendees. A major portion of the meeting which discussed in detail the proposed repair method, which utilizes a rolling  !

process and expansion plugs, was proprietary.

Details of the repair process, the qualification of the repair process, i examinations which will be performed on the penetrations prior to performing '

repairs, requirements for ensuring adequate repairs, method to prevent i repaired penetration ejection, and details of the unreviewed safety question .

evaluation were discussed. The analysis performed in support of the proposed t repair method included consideration for normai operation, accident ,

conditions, and transients. It was noted that the proposed repair process  :

should result in no degradation to the pressurizer because the repairs result in secondary vessel stress without permanent deformation and no resultant i metallurgical effects on the pressurizer. i An overall summary of the presentation is included in the enclosed outline.

The NRC staff identified three items for BG&E to further consider prior to  !

making its submittal. The first item was related to the acceptance criteria i for continued service as it relates to the current technical specifications ,

requirement of no primary pressure boundary leakage. The second item was a j request that any additional test related data or information related to  !

crevice corrosion of Inconel Alloy 690 be provided. Finally, it was noted ,

that there appeared to be interest in the proposed repair process by other i utilities and, if this is the case, the proposed request should be submitted  !

as a lead plant due to the potential generic use.

Orginal signed by:

Daniel G. Mcdonald, Senior Project Manager

Project Directorate I-I Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation

Enclosures:

1. Attendees

2. Presentation Outline .

cc w/ enclosures:

See next page Distribution:

See attached sheet n LA:PDI-l PM:PDI-l h k D:PDI-l CVogan 0 (F DMcDonald mm RACapra #

if/h93 $ /h 93 10 /23 /93 / / / / / / l OFFICIAL RECORD COPY FILENAME: CC50317.MTS

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