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Summary of ACRS Subcommittee on Metal Components & Thermal Hydraulic Phenomena 871215 Meeting W/Vepco & Westinghouse in Washington,Dc Re Steam Generator Tube Rupture Failure & Dl Johnson Comments on Criteria for ECCS Rule
	ML20148K092
Person / Time
Site:	North Anna
Issue date:	01/22/1988
From:	; Advisory Committee on Reactor Safeguards
To:	; Advisory Committee on Reactor Safeguards
References
	ACRS-2541, NUDOCS 8801270546
	Download: ML20148K092 (14)
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CERTIFIED COPY

.I DATE ISSUED: Jan. 8,1988

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'N" SUtiMARY/PINUTES OF THE JOINT ACRS SUBCOMMITTEE ON METAL COMPONENTS Afl0 THERMAL HYDRAULIC PHENOMENA DECEMBER 15, 1987 WASHINGTON, D.C.

The /CRS Subcommittees on Metal Components and Thermal Hydraulic Phenomenon met on December 15, 1987 in Washington, D.C. to review 1) the North Anna, Unit 1, steam generator tube rupture failure and 2) D. L.

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Johnson's comments on proposed revision to acceptance criteria for the ECCS rule with respect to steam generator tube integrity.

f:otice of the meeting was published in the Federal Register on December 7,1987(AttachmentA).

The schedule of items covered in the meeting is in Attachment B.

A list of the handouts filed with the office copy of the minutes is included in Attachment C.

There were rc written or oral j

statements received or presented from members of the public at this nieeting.

F. Igne and P. Boehnert were the cognizant ACRS Staff members for the meeting.

8801270546 880122 PDR ACRS PDR 2541 Principal Attendaes:

NRC J. Richardson, NRR ACRS G. Murphy, NRR T). Shewmon, Chairman, Metal Corrponents Subc, N. Laubew, RES D. Ward, Chairman, Tiiermal Hydr. Phenon, C. Michelson, Member VEPC0 G. Reed, Member M. L. Bowling C. Wylie, Member D. Vande Walle J. Ebersole, Merrt'er P. Boehnert, ACRS Staff E. Igne, ACRS Staff W. Kerr, Member Westinghouse Electric 3 gIeg Consultant K. Huffman k[.

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DESIGNATED ORIGINAL

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flinutes/ Joint Subcommittee Mtg.

2 Metal Components & Thermal Hyraulic Phenomenon, Dec. 15, 1987 w

E. Rodabaugh, ACRS Consultant T. Pitterle I. Carron, ACRS Consultant G. Whiteman Other D. L. Johnson Highlights:

1.

M. L. Bowling, VEPC0, discussed the July 15, 1987 stean generator tube rupture event at North Anna, Unit 1, and the evaluations and following actions performed and planned by VEPCO. He discussed the detailed sequence of events including the response of the operators and key plant equipment, the radiological effects of the events; VEPC0's evaluation of the implementation of this emergency plans, the safety consequences and significance of the event, and the lessons learned and corrective actions taken or planned by VEPC0 is a result of the event.

2.

From the operational aspects, he stated that a) the safety related equipment responded as expected b) the ruptured steam generator was isolated within 13 minutes without overfilling or lifting safety valves and c) the DCS pressure stablized within 34 minutes without lifting safety valves and going solid in the pressurizer.

3.

With reoard to the impact on safety, he stated that a) the event was bounded by the plant's events analyzed in the updated FSAR, b) the core safety limits were not exceeded c) the shutdown and thermal margins were maintained and d) the radioactive releases were significantly less than 10 CFR 100 limits.

i

Minutes / Joint Subcommittee Mtga 3

Metal Components & Thermal Hyraulic Phenomenon, Dec. 15, 1987 4.

M. L. Bowling, stated that the basis for plant restart includes the following:

reduced local fluid forces by adding downcomer flow resistance

pistes, preventive plugging of susceptible tubes, and improved leakage monitoring.

l l

i 5.

With respect to leakage monitoring, the following methods are enployed:

I N-16(continuous)

Air ejector radiation monitor (ever a burs),

l l

Air ejector grab samples (every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months ), and Primary and secondary isotopics (every 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ) l l

He stated that if leakage exceeds 100 gpd from one steam generator (or 300 gpd total), the plant will be placed in hot shutdown within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

l If there is a increase in leakage from all steam generators exceeding 60 l

l gpd between surveillances, the plant will reduce power below 50% within 90 minutes.

These criteria should provide ample time to prevent tube-rupture by high cycle fatigue.

6.

K. Huffman, Westinghouse Electric Corp, discussed the failure mechanism which was involved in the North Anna event.

The steam generator was a Model 51 manufactured by Westinghouse Electric Corp.

The tubes are fabricated of mill annealed alloy 600 tubes.

Minutes / Joint Subcomittee Mtg.

4 Metal Components & Thermal Hyraulic Phenomenon, Pec. 15, 1987 The support plates are of carbon steel. The failure was co ;ea by high cycle fatigue and had'not been previously encountered.

upper support plant denting which constrains the tubes causing lower damping and high mean stress in the tubes, and flow induced tube vibration which causes excessive deflection in the unsupported tube.

The excessive tube vibration, low damping, and high mean stress can result in a high cycle fatigue failure.

k'estinghouse's approach to solving the problem was to reduce the flow induced vibration by adding a downcomer resistance plate.

Experiments and analysis confirmed that this reduced the flow induced vibration to a level which would not cause high cycle fatigue failure.

7.

Other plants which may have this same problem are being investigat-ed by the industry and the NRC Staff.

The plants identified with the potential for this seme tube fatigue problem are Indian Point 2&3, Point Beach, Haddam Neck, and Salem.

8.

Mr. Dan L. Johnson discussed his concerns regarding steam generator tube integrity. His concerns can be summarized as follows:

1 There have been, and are, continuing problems with loss of steam generator tube integrity caused by various degradation mechanisms (e.g. denting, fretting, corrosion,etc.)

)

Minutes / Joint Subcommittee Mtg.

5 Metal Components & Thermal Hyraulic Phenomenon, Dec. 15, 1987 The hydraulic loads expected during a large break LOCA could cause multiple steam generator tube ruptures and this issue should be addressed.

1 Rupture of a large number of tubes raises the issue of return to power or recriticality due to dilution of borated reactor coolant system water by the intrusion of secondary system water.

Rupture of the right number of steam generator tubes may excerbate steam binding and hinder core refill /reflood.

In response to Mr. Reed, Mr. Johnson indicated that his concerns are greatly reduced in importance if the "classical" - large break LOCA is not deemed to have a significant probability for occurring.

N. Lanbew (RES) discussed the NRC response to Mr. Johnson's concerns.

RES agrees that Mr. Johnson concerns should be evaluated. A Generic Issue (GI-lal, "Larce Break LOCA concurrent with Steam Generator Tube Rupture") has been established for these concerns. The Generic Issue will be prioritized by the NRC by February, 1988.

D. Ward stated that he is satisfied with the NRC Staff's approach for evaluating this issue.

NOTE:

Additional meeting details can be obtained from a transcript of this meeting available in the NRC Public Document Room, 1717 H St., NW., Washington, D.C. or can be purchased from Heritage Reporting Corporation, 1220 L Street, NW.,

Washington, D.C. 20005, (202) 628-4888.

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ATTACHMENT A s

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1 46426 Fedir:1 RegNttr / Vol. 52, No. 234 / Monday, Dzcember 7.1987 / Notices i

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'. EAR REGULATORY.

scheduled mecung to be advised of any For the Nuclear Regulatory Commise4on.

i

. MISSION

( m.; *. e m.=

changes in schedufg etc.. which mar Eric S. Bed)ont.

have occurred.

Director. O/ lice olNucher Aarebeory l [ Safeguards; Joint Subcommittees on.

Rescod j

dvisory Committet on Reactor -

Date: Decemler t.19s7..

[FR Doc. 87-20000 Filed 12-4-47; 6 45 em] '

N " E UW Metal Components and Thermal oumeo coot news-m

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Hydraulic Phenomena; Notice og Assistant becutive Director)6e Project

. v. -

Review.

% %ng

.4 In Doc. 87 28019 Filed 12-4-47; at45 ava)

Flegu'.atory Gulde; lasuance, ne ACRS Subcommittees on Metal

,u,,, eaa r.,ww Aval'ablitty Components and %ertnal Hydraulic 1

f Phenomena will bold a joint meeting on We Nuclear Regulatory Commission has istved a new guide in its Regulatory December 15,1967, Room 1046,1717 H Regulatory Guido;lasuance, '. - 4 i

j Street. NW,. Washington. DC AvailabWty

$i Guide Series.nis series hes been To the extent practical the meeting developed to describe and make -

will be open to public at endance...

%e Nuclear Regulatory Commis'slon.

available to the public such information

.lowever, protions of the meeting may.

has 1: sued a revision to a guide in its -

as methods acceptable to the NRC staff be closed to discuss Westinghouse.

Regulatory Guide Series.nis series has for implementing specific parts of the proprietary information.

been developed to describe and make Commission's regulations, techniques The agenda for the subject rnecting available to the public such information used by the staffin evaluating specific shall be as follows:'

as rnethods acceptable to the NRC staff problems or postulated accidents. and Tuesday, December 15.1967--&J0 o.m.

for implementing specific parts of the data needed by the staff in its review of untilthe conclusion of business Commission's regulations, techniques applications for permtis and licenses.

%e Subcommittees will review:(1) used by the staffin evaluating specific Regulatory Guide 1.156, ne North Anna steam generator tube problems or postulated accidents, and Environmental Qualification of failure, and (2) R.L Johnson's comments data reeded by the staffin its review of Connection Assemblies for Nuclear on proposed revision to acceptance applications for permits and licenses.

Power Plants," describes a method criteria for the ECCS rule with respect to Revision 1 to Regulatory Guide 5.62 acceptable to the NRC staff for steam generator tube Integrity.

"Reporting of Safeguards Events,"

environmental qualification of quick-Oral statements may be presented by provides an approach acceptable to the disconnect connection assemblies for

, members of the public with the NRC staff for detenntning when and service in nuclear power plants. %e l qncurrence of the Subcommittee how an event should be reported. nese guide endorses IEEE Std 572-1985, irman; wntten statements will be safeguards events are those that "Qualification of Class IE Connection

)pted and made available to the threaten nuclear activities or lessen the Assemblies for Nuclear Power

...nmittee. Recordings will be permitted effectiveness of a security system.

Generating Stations."

only during those portions of the Comments and suggestions in Comments and suggistions in meeting when a transcnpt is be

kept, connection with (1) items for inclusion ' connection with (1) items for inclusion and questions may be asked only y in guldes cunently being developed or in guides currently being developed or

sk (2) Improvements in all published guides (2) improvements in all published guides gn t s are enc ureged at any time. Written are encouraged at any Ume. % ritten to make oral statements should notify comments may be submitted to the comment' may be submitted to the.

i g3e ACRS sta[f member named below as

( far in advance as la practicable so that '

Rules and Procedures Branch, Div;sion Rules ar.d Procedures Branch Division of Rules and Records. Office of of Rules and Records, Office of 1

i appropriate arrangements can be made' Administration and Resources Administration and Resources l

During the initial portion of the Management, U.S. Nuclear Regulatory Management. U.S. Nuclear Regulatory mag Commission. Washington, DC 20555.

Commission. Wa shington, DC 20555.

ny s nsu n inspection at the Ccmmission,able f present, may exchange preliminary Regulatory guides are available for Regulatory guides are avail s Public views regarding matters to be inspution at the Commission s Public D cument Room,1717 H Street NW Documents Room.1717 H Street NW.,

j considered during the balance of the Washington DC. Copies ofissued Washington, DC. Copies of issued meeting' bcommittee will then hear guides may be purchased from the guides may be purchased from the ne Su i

presentations by and hold discussioni Govemment Printing Office at the Government Printing Office at the with representatives of the NRC Stafff:

current GPO price. Information on current GPO price. Information on its consultants, and other interested cwent GPO prices may be obtained by current GPO prices may be obtained by contacting the Superintendent of.

contacting the Superintendent of

[

persons regarding this review.s,

Further informa tion regarding topics a Documents, U.S. Government Printiqg,

Documents. U.S. Government Printing.

Ito be discussed, whether the meeting,

Office, Post Office Doz 37082, Office, Post Office Box 37082, ha: been cancelled or escheduled, the ;

Washington. DC 20015-7082, telepho~ e Wa shington, DC 20013-7082. tclephone n

Chalanan's ruhn6 on r'equests for the i.. (202) 275-2000 or (202) 275-2171. Issued (2D2) 275-2000 or (202) 275-2171. Issued oppottunity l'o present oral staternents l guides may also be purchased from the.

guides may also be purchased from the obtained by a prepaid telephone calit'*,. NationalTechnical Information Service and 64 time allotted therefor can be National Technical Informa tion Service i

on a standing order basis. Details on on a standing order basis. Details ou the ex>gnizant ACRS staff mem6er, Mr..t this service may be obtained by writing this service may be obtained by writing o

Elpidio Igne (telephons 202/634-3287}i hTIS. 5285 Port Royal Road, Springfield.

NTIS,5285 Port Royal Road, Springfield.

,.between 8;15 aJa. and 5:00 pan. Persons

. ' (,,

VA 22161.

ged to contact the above n(amed1mning to attend this meet ng arg,

(5 U.S.C. 552(e9 (5 U.S C. 55 tal)

Daled at Rockville. Maryland, this 1st day Dated at Rockville. Maryland, this 1st day andividual one or two days before the.

of December ios7.

of December 1967,

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i ATTACHMENT B i

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s' DRAFT #3 IGNES: AGENDA MC

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TENTATIVE AGENDA JOINT SUBCOMMITTEE MEETING METAL. COMPONENTS / THERMAL HYDRAULIC PHENOMENA ON STEAM GENERATOP. INTEGRITY WASHINGTON, D.C.

DECEMBER 15, 1987 8:30 - 8:45 a.m.

I.

Chairman's Statements 8:45 - 10:00 a.m.

II.

North Anna Steam Generator Tube Failure

- VEPC0 Presentation (Suggested Topics)

. Introduction & Background

. Sequence of Events

. Operators Action

. Leak rate & Detection

. Lessons Learned 10:00 - 10:15 a.m.

BREAK 10:15 - 12:15 p.m.

W Presentation

. Metalurgical Examination

. Mechanism of Failure

. Fracture Mechanics and Strength Analysis

. Stability of Tubes, Structural /

Fluid Flow Interactions

. Propose fixes and basis

. Generic Implications

. Discussion on multiple tube

_ _t, ruptures 4h45-4+45 p.m.

NRR Discussion Will be available to answer Subcommittee's questions

'2'Ci - U65 JrI5 - 2:15 p.m.

LUNCH III. D. L. Johnson's Concern on Steam Generator Integrity g., w 2j[5-p.m

. Johnson's presentation 3.'0 {

9

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Agenda MC & TH Steam Generator 2

Integrity Mtg.

3'.05 E.' t b BREAK p 45 - M p.m.

i Discussion by NRC Staff e,.

T h, A 00 - 4jl5 p.m.

- Office of Research, N. Lauben Office of NRR, (Will be 4:15.- 4:45 p.m.

available to answer 4 0> -4'.1o g, Subconinittee's questions) 4:45 - 5:00 p.m.

IV.

Subconsnittee Discussion & Adjournment o Proposed Action Items

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TENTATIVE AGENDA JOINT SUBCOMi!TTEE NEETING METAL COMPONENTS / THERMAL HYDRAULIC ON STEAM GENERATOR INTEGRITY WASHINGTON, D.C.

DECEMBER 15, 1987 8:30 - 8:45 a.m.

I.

Chairmar.'s Statements 8:45 - 10:00 a.m.

II.

North Anna Steam Generator Tube Failure VEPCO Presentation L(M. L. Bowling, Assistant Station Manager)

. Introduction

. Sequence of Events

. Operational Aspects

. Impact on Safety and Radiological Effects

. Basis for Return tc Service

. Lessons Learned 10:00 - 10:15 a.m.

- - - - BREAX *******

10:15 - 12:15 p.m.

- M Presentation

[(X. L. Huffman, Manager) )

NDE Center and STD Programs

. Failure Mechanism

. Steam Generator 'C',

R9C51 Tube Condition

. Corrective Actions

. Generic Considerations i

ATTACHMENT C l

HANDOUTS FOR DECEMBER 15, 1987 SUBCOMMITTEE MEFTING 1.

North Anna Unit 1, July 15, 1987 Steam Generator Tube Rupture Event Presentation, December 10, 1987, Revision 3 2.

Memo to Carl H. Berlinger, Generic Communications Branch Chief, Division of Operational Events Assessment, dated December 15, 1987' from W. J. Johnson, Manager, Nuclear Safety Dept. Westinghouse Electric Corp.

Subject:

North Anna Unit 1 Steam Generator-Evaluation 3.

Slides on:

1.

High Cycle Fatigue Failure 2.

Dented, Unsupported Tubes 3.

Local Flow Effects Important 4.

Few Tubes Potentially Involved

,

ML20148K092

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