ML20206U000

Forwards Revised Marked Up Proposed Tech Specs,Re Criterion for Plugging Steam Generator Tubes,Reflecting Change in Wording of Proposal.Changes Not Functionally Different from Changes in 860624 Submittal

ML20206U000
Person / Time
Site:	Mcguire, McGuire
Issue date:	07/01/1986
From:	Tucker H DUKE POWER CO.
To:	Harold Denton, Youngblood B Office of Nuclear Reactor Regulation
References
TAC-61775, TAC-61776, NUDOCS 8607080282
Download: ML20206U000 (8)

Text

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DUKE POWER GOMPANY {

P.O. BOX 33189 l

OHARL(YITE, N.O. 28242 l

.HALH.TUGKER M LEPHONE (704) ara-4mi l l

. July 1, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 ATTENTION:; g if i J.] @ loodi Director  !

PWR Directorate No. 4

Subject:

McGuire Nuclear Station, Units 1 and 2 '

Docket No. 50-369, 50-370 Steam Generator Tube Plugging Criteria i l

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Dear Mr. Denton:

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By letter dated June 24, 1986, Duke. Power proposed changes to the McGuire Nuclear Station Technical Specifications to incorporate the P* criterion for plugging steam generator tubes. As a result of discussions between our respective staffs, a change in the wording of the proposal has been agreed upon. The intent and results of the proposed changes remain unchanged.

The attachment inc1udes the revised marked up pages. As these changes are not functionally different from those transmitted in my l'atter of June 24, 1986, the Justification and Safety Analysis and Analysis of Significant Hazards Considerations included in the June 24 submittal remain un' changed.

As this submittal supplements an earlier proposal, no fees are enclosed.

Please feel free to contact us if you require any additional information.

Very truly yours, Hal B. Tucker JBD/39/jgm ,

00 Attachment g su$$ir P

Mr. Harold R. Denton July 1, 1986 Page 2 J

xc: Dr. J. Nelson Grace Mr. Dayne Brown, Chief Regional Administrator Radiation Protection Branch '

U.S. Nuclear Regulatory Commission Division of Facility Services Region II Dept. of Human Resources 101 Marietta Street, NW, Suite 2900 P.O. Box 12200 Atlanta, Georgia 30323 Raleigh, N.C. 27605 Mr. W.T. Orders Mr. Darl Hood, Project Manager l NRC Resident Inspector Division of Licensing McGuire Nuclear Station Office of NRC Washington, D.C. 20555 3

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ATTACHMENT

REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continued)

1) All n'onplugged tubes that previously had detectable wall penetrations (greater than 20%),

2) Tubes in those areas where experience has indicated potential problems, including all adjacent intact tubes, and l

3) A tube inspection (pursuant to Specification 4.4.5.4.a.8) sha.ll be performed on each selected tube. If any selected tube does not permit the passage of the eddy current probe for a tube

' inspection, this shall be recorded and an adjacent tube shall be selected and subjected to a tube inspection.

c. The tubes selected as the second and third samples (if required by Table 4.4-2) during each inservice inspection may be subjected to a partial tube inspection provided: .

! 1) The tubes selected for these samples include the tubes from those areas of the tube sheet array where tubes with imperfections were previouEly found, and .

2) The inspections include those portions of the tubes where I imperfections were previously found.

The results of each sample inspection shall be classified into one of the following three categories: ,

Category Inspection Results C-1 Less than 5% of the total tubes inspected are degraded tubes and none of the inspected tubes are defective.

C-2 One or more tubes, but not more than 1% of the total tubes inspected are defective, or between 5% and 10% of the total tubes inspected are degraded tubes. i C-3 More than 10% of the total tubes inspected are l degraded tubes or more than 1% of the inspected l tubes are defective.

Note: In all inspections, previously degraded tubes must exhibit significant (greater than 10%) further wall penetrations i

to be included in the above percentage calculations.

l McGUIRE - UNITS 1 and 2 3/4 4-12 l

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REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continued) 4.4.5.4 Acceptance Criteria

a. As used in this specification:

1) Imperfection means an exception to the dimensions, finish or contour of a tube from that required by fabrication drawings or specifications. Eddy-current testing indications below 2 5 of

- the nominal tube wall thickness, if detectable, may be considered as imperfections; i

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2) Degradation means a service-induced cracking, wastage, wear or general corrosion occurring on either inside or outside of a tube;

3) Degraded Tube means a tube containing imperfections greater

• than or equal to 20% of the nominal wall thickness caused by degradation;

4)  % Degradation means the percentage of the tube wall thickness ,

affected or removed by degradation; .

5) Defect means an imperfection of such severity that it exceeds A the plugging limit. A tube containing a defect is defective; Plugging Limit means the imperfection depth at or beyond  !

6) which the tube shall be removed from service and is equal to 40% of the nominal tube wall thickness. This defini-tion does not apply to the area of the tubesheet region below the P* distance provided it has been verified that the adjacent tube is intact. If during inspections any adjacent tube is found to be degraded in any part of the tube, then the tube below it (with an imperfection below P* exceeding the plugging limit) shall be plugged.

7) Unserviceable describes the condition of a tube if it leaks or contains a defect large enough to affect its structural integrity in the event of an Operating Basis l

Earthquake, a loss-of-collant accident, or a steam line or feedwater line break as specified in 4.4.5.3c, above;

8) Tube Inspection means an inspection of the steam generator tube from the point of entry (hot leg side) completely around the U-bend to the top support of the cold leg; and i

McGUIRE - UNITS 1 and 2 3/4 4- 14

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REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continued)

9) Preservice Inspection means an inspection of the full length of each tube in each steam generator performed by eddy current techniques prior to service to establish a baseline condition of the tubing. This inspection shall be performed after the field hydrostatic test and prior to initial POWER OPERATION using the equipment and techniques expected to be used during subsequent inservice inspections. ,

10) Adjacent Tube is the tube one row higher and in the same column.

11) Intact Tube is a tube that is not a degraded tube.

12) P* Distance is the distance into the tubesheet from the top face of the tubesheet that has been conservatively chosen to be 2 inches.

b. The steam generator shall be determined OPERABLE after completing the corresponding actions (plug all tubes exceeding the plugging limit and all tubes containing through-wall cracks) required by Table 4.4-2. .

4.4.5.5 Reports

a. Within 15 days following the completion of each inservice inspection of steam generator tubes, the number of tubes plugged in each steam generator shall be reported to the Commission in a Special Report pursuant to Specification 6.9.2; .

b. The complete results of the steam generator tube inservice inspection shall be submitted to the Commission in a Special Report pursuant to Specification 6.9.2 within 12 months following the completion of the inspection. This Special Report shall include: ,

1) Number and extent of tubes inspected,

2) location and percent of wall-thickness penetration for each indication of an imperfection, and

3) Identification of tubes plugged.

Amendment No. (Unit 1) u,cnt u . nurTc 1 ana 9 1/4 4-M Amendment No. (Unit 2)

REACTOR COOLANT SYSTEM 8ASES 3/4.4.4 RELIEF VALVES The power-operated relief valves (PORVs) and steam bubble function to relieve RCS pressure during all design transients up to and including the design step load decrease with steam dump. Operation of the PORVs minimizes l

the undesirable opening of the spring-loaded pressurizer code safety valves.

Each PORV has a remotely operated block valve to provide a positive shutoff capability should a relief valve become inoperable. l 3/4.4.5 STEAM GENERATORS  ;

The Surveillance Requirements for inspection of the steam generator tubes ensure that the structural integrity of this portion of the RCS will be main-tained. The program for inservice inspection of steam generator tubes is based on a modification of Regulatory Guide 1.83, Revision 1. Inservice  ;

j inspection of steam generator tubing is essential in order to maintain <

surveillance of the conditions of the tubes in the event that there is evidence of mechanical damage or progressive degradation due to design,

• manufacturing errors, or inservice conditions that lead to corrosion.

Inservice inspection of steam generator tubing also provides a means of l

characterizing the nature and cause of any tube degradation so that corrective

measures can be taken.

I The' plant is expected to be operated in a manner such that the secondary

' coolant will be maintained within those chemistry limits found to resul't in negligible corrosion of the steam generator tubes. If the secondary coolant chemistry is not maintained within these limits, localized corrosion may likely result in stress corrosion cracking. The extent of cracking during ,

plant operation would be limited by the limitation of steam generator tube i leakage between the Reactor Coolant System and the Secondary Coolant System

(reactor-to secondary leakage = 500 gallons per day per steam generator).

j Cracks having a reactor-to-secondary leakage less than this limit during 1

operation will have an adequate margin of safety to withstand the loads j imposed durJog normal operation and by postulated accidents. Operating plants

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have demonstrated that reactor-to-secondary leakage of 500 gallons per day per j steam generator can readily be detected by radiation monitors of steam j generator blowdown. Leakage in excess of this limit will require plant 1 shutdown and an unscheduled inspection, during which the leaking tubes will be

! located and plugged.

Wastage-type defects are unlikely with proper chemistry treatment of the i secondary coolant. However, even if a defect should develop in service, it will be found during scheduled inservice steam generator tube examinations.

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l Plugging will be required for all tubes with imperfections in the free f span region and within the P* distance exceeding the plugging limit of 40% of the tube nominal wall thickness. Steam generator tube inspections of operating plants have demonstrated the capability to reliably detect l degradation that has penetrated 20% of the original tube wall thickness. (

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McGUIRE - UNITS 1 and 2 8 3/4 4-3 l 1

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Fcr tubes with imperfections found greater than two inches below the top of the tubesheet, plugging is. not required except when the adjacent tube is a d: graded tube as defined by Specificaton 4.4.5.4. The acceptance criteria of Specification 4.4.5.4 (degraded tube) applies to the full length of the tube.

The definition of an intact tube is conservatively taken to be a tube that is not a degraded tube (no indication is greater than 20% through wall). Should future evaluations justify a value that is less conservative, the definition of intact tube may be changed. Similarly, the distance into the tubesheet from the top face of the tubasheet, the P* value, is conservatively chosen to bn two inches. This includes the factors discussed in the Westinghouse Safety Evaluation report (which resulted in a P* value of 1.282 inches) with ca additional uncertainty for eddy current testing. Further evaluations may justify a reduction in the P* value of two inches, at which time that may be changed.

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l l McGuire - Units 1 and 2 B 3/4 4-3a

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