ML20235V393

Proposed Tech Specs 3/4.4,changing Steam Tube Plugging Criteria to Allow Adoption of F* Criteria

ML20235V393
Person / Time
Site:	Catawba
Issue date:	10/08/1987
From:	DUKE POWER CO.
To:
Shared Package
ML19304B580	List: ML20235V365 ML20235V381 ML20235V393 ML20235V427
References
NUDOCS 8710150126
Download: ML20235V393 (8)

Text

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'_, i TECHNICAL SPECIFICATION CHANGES h

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[- REACTOR COOLANT SYSTEM l

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. SURVEILLANCE REQUIREMENTS (Continued) l

-1) :All nonplugged tubes that previously had detectable wall penetrations:(greater than 20%),

'2) Tubes .in'those areas where experience has indicated potential

. ' problems, and

3) A tube inspection (pursuant-to Specification 4.4.5.4a.8) shall 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.

The: tubes selected as the second and third samples.(if required by Jk 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 ar' ray where tubes with imperfections were previously found, and

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

The results of each sample inspection shall be classified into one of the

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'following three categories:

Cateaory Inspection Result 3 C-1 Less than 5% of the total tubes-inspected are degraded tubes and none of-the inspected tubes are defective.

l 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.

C-3 More than 10% of the total tubes inspected are 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 to be included in the above percentage calculations.

CATAWBA - UNITS'1 & 2 3/4 4-13

REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continued)

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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 20% of the nominal tube wall thickness, if detectable, may be considered'as imperfections;

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 tnan 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 the plugging limit. A tube containing a defect is defective;

6) Pluggina Limit means the imperfection depth at or beyond which the tube shall be removed from service and is equal to 40%

ofthenominaltubewallthickness]/.

7) Unserviceable describes the condition of a tube if it leaks or contains a defect large enough to affect its structural integ-rity in the event of an Operating Basis Earthquake, a loss-of-coolant accident, or a steam line or feedwater line break as specified in 4.4.5.3c., above;

8) Tube Insoection means an inspection of the steam generator tube from the point of entry (hot leg side) com etel around the U-bend to the top support of the cold leg; for U Mk $ , $N\s de[ inn $n Yoes nok offll $6 he re icn of .

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CATAWBA - UNITS 1 & 2 3/4 4-15  ;

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f SURVEILLANCE REQUIREMENTS (Continued) 'l

9) Preservice Inspection means an. inspection of the full length of each tube in each steam generator.perforcod by. eddy current-techniques prior to servi.ce to establish a baseline' condition h of the tubing. This inspection shall be performed prior to

• initial POWER OPERATION using the equipment and techniques expected to be used during subsequent inservice inspections.

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. b .- .The steam generator shall be determined OPERA 8LE after completing the corresponding actions (plug all tubes exceeding the plugging j

' limit and all tubes containing through-wall cracks) required by t Table 4.4-2. F;,r und 1, hLs vin J,fe.cis W = F4 b(I uncler Me ' - l O A# # A 4.4.5.5 Reports

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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, Location.and percent of wall-thickness penetration for each i

2) indication of an imperfection, and 4

3) Identification of tubes plugged.

f# c suits of steam generator tube inspections, which fall into Category t 3, shall be reported in a Special Report to the Commission pursuant to Specification 6.9.2 within 30 days and prior to resumption of plant operation. -This report shall provide a description of investigations conducted to determine cause of the tube degradation and corrective measures taken to prevent recurrence.

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CATAWBA - UNITS 1 & 2 3/4 4-16

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I INSERTION A 10)' Tube Roll Expansion is that portion of.a tube which has been increased in.  ;

diameter by a rolling process such that no crevice exists between the  ;

outside, diameter of the tube and the tubesheet.

11). F* Distance is the minimum length of the roll expanded portion of the tube which cannot contain any defects in order to ensure the-tube does not pull. ,

out of the tubesheet. The F*. distance is 1.31 inches and is measured from

.the top of the roll expansion of the tube down toward the bottom of the tubesheet. Included in this distance is a safety factor of 3 plus a 0.25 inch eddy current vertical measurement uncertainty.

12) Alternate tube plugging criteria does not require the tube to be removed form service or repaired when the tube degradation exceeds the plugging limit so long as the degradation is in that portion of the tube from F* to the bottom of the tubesheet.

INSERTION B

d. For Unit 1, the results of inspections for all tubes for which the alternate tube plugging criteria has been applied shall be reported to the Nuclear Regulatory Commission in accordance with 10 CFR 50.4, prior to restart of the unit following the inspection. This report shall include:

1) Identification of applicable tubes, and

2) Location and size of the degradation.

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8ASES

' STEAM GENERATORS (Continued) generator tubes is based on a modification of Regulatory Guide 1.83, Revision 1.

Inservice inspection of steam generator tubing is essential in order to main-tain' surveillance of the conditions of the tubes in the event that there is evidence of mechanical damage or progressive degradation due to design, manu-facturing errors, or inservice conditions that lead to corrosion. Inservice inspection of steam generator tubing al.so provides.a means.of characterizing the nature and cause of any tube degradation so that corrective measures can be taken.

The plant is expected to be operated in a manner such that the secondary coolant will be maintained within those chemistry limits found to result in negligible corrosion of the steam generator tubes. If the secondary coolant chemistry.is not maintained within these limits, localized corrosion may 1ikely result in stress corrosion cracking. The extent of cracking during plant operation would be limited by the limitation of steam generator tube leakage between the Reactor Coolant System and the Secondary Coolant System (reactor-to-secondary leakage = 500 gallons per day per steam generator).

Cracks having a reactor-to-secondary leakage lass than this limit during operation will have an adequate margin of safety to withstand the loads imposed during normal operation and by postulated accidents. Operating plants have '

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

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

plugging will be required for all tubes with imperfections exceedina the J  !

plugging' limit of 40% of the tube nominal wall thickness. (Steam generator y j

tube inspections of operating plants have demonstrated the capability to reliably detect degradation 3

that has penetrated 20% of the original tube wall g thickness. g e, ,

Whenever the results of any steam generator tubing inservice inspection f all into Category C-3, these results will be reported to the Commission pur-suant to Specification 6.9.2 prior to resumption of plant operation. Such  ;

cases will be considered by the Commission on a case-by-case basis and may j result in a requirement for analysis, laboratory examinations, tests, additional i eddy-current inspection, and revision of the Technical Specifications, if I necessary. {

l- 3/4.4.6 REACTOR COOLANT SYSTEM LEAKAGE j

3/4.4.6.1 LEAKAGE DETECTION SYSTEMS l

The Leakage Detection Systems required by this specification are provided 4 to monitor and detect leakage from the reactor coolant pressure boundary.

CATAWBA - UNITS 1 & 2 8 3/4 4-3

WCAPs 11581 AND 11582 i

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