ML20126F273

Suppl 1 to Proposed Change 108 to Tech Spec 4.10 Re Steam Generator Tube Surveillance Requirements for Category C-3 Insp Results

ML20126F273
Person / Time
Site:	Maine Yankee
Issue date:	06/11/1985
From:	Maine Yankee
To:
Shared Package
ML20126F249	List: ML20126F245 ML20126F273
References
578OL-SEN, NUDOCS 8506170422
Download: ML20126F273 (5)

Text

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MAIN 3 YANKEE ATCMIC POWER COMPANY Category Inspection Results 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 degradesd tubes or more than 1% of the inspected tubes are defective.

Note: In all inspections, previously degraded tubes must exhibit significant (greater than 104) further wall penetrations to be included in the above percentage calc.ulations.

C. Inspection Frequencies - The above required inservice inspections of ateam generator tubes shall be performed at the following frequencies:

1. Inservice inspections shall be performed at intervals of not less than ]

12 nor more than 24 calendar months after the previous inspection. If two consecutive inspections following service under AVT conditions, not includino the preservice inspection, result in all inspection results falling into the C-1 category or if two coniccutive inspections demonstrate that previously observed degradation has not continued and no additional degradation has occurred, the inspection interval may be extended to a maximum of once per 40 months.

2. If the results of the inservice inspection of a steam generator conducted in accordance with Table 4.10-2 at 40 month intervals fall in Category C-3, the inspection frequency shall be increased to at 1 cast once por 20 months. The increase in inspection frequency shall apply until the subsequent inspections meet the conditions specified in C-1 and the interval can be extended to a 40 month period.

3. Additional, unscheduled inservice inspections shall be performed on each steam generator in accordance with the first sample inspection specified in Table 4.10-2 during the shutdown subsequent to any of the following conditions.

(a) Primary-to-secondary tube leaks (not including leaks originating from tube-to-tuce sheet welds) in excess of the limits or Specification 3.14.C.5, ))

(b) A main steam line break or feedwater line break, (c) A seismic occurrence greater than the Operating Dasis Earthquake, or (d) A loss-of-coolant accident requiring actuation of the engineered sarcQuards.

D. Acceptanco criteria

1. As used in this Specification.

(a) Imerfection 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 204, of the nominal tube wall thickness may be con:.idered as imperfections.

61gg 4.10-2 06/11/85 5700L-SEN .

MAINE YANK ] ATOMIC POWEQ COMPANY (b) Degradation means a service-induced cracking, wastage, wear or general corrosion occurring on either inside or outside of a tube.

(c) Degraded Tube means a tube containing imperfections greater than or ]

equal to 20% of the nominal wall thickness caused by degradation. ]

(d) % Degradation means the percentage of the tube wall thickness affected or removed by degradation.

(e) Defect means an imperfection of such severity that it exceeds the plugging limit. A tube containing a defect is defective.

(f) Plugging Limit means 'the imperfection depth at or beyond which the ]

tube shall be removed from service because it may become unserviceable prior to the next inspection and is equal to 40% of the nominal ]

tube wall thickness.

(g) 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 a steam line break, feedwater line break, Operating Basis Earthquake, or a loss-of-coolant accident as specified in 4.10.c.3 above.

(h) Ttbe 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.

(1) Critical Area means an area of the steam generator where degraded ]

and/or defective tubes exist due to a steam generator physical and/or ]

operating characteristic which would promote tube degradation in that ]

Identified area. ]

2. The steam generator shall be determined OPERA 0LE after completing the correcponding actions (plug all tubes exceeding the plugging limit and all tubes containing through-wall cracks) required by Table 4.10-2.

EXCEPTION The steam generator shall be determined operable without performing 100% ]

tube inspection required by Table 4.10-2 when the first or subsequent ]

sample inspection results are at the C-3 level due to defects in a critical ]

area, provided: )

(a) The critical area (s) are identified and bounded. ]

(b) A 100% inspection of the critical area is conducted. ]

(c) A steam generator tube inspection is conducted for the sample size ]

required by Specification 4.10.0 excluding those tubes and results from ]

the inspection of the critical area (s). ]

4.10-3 06/11/85

[ 5780L-SEN

P,

, , MAIN 3 YANKE3 ATOMIC POWER COMPANY E. Reports

1. Following each inservice inspection of steam generator tubes, the 3 number of tubes plugged in each steam generator shall be reported T to the Commission within 15 days.

2. The complete results of the steam generator tube inservice inspection shall be included in the "NIS-1 Owners Data Report for Inservice .

Inspections" for the period in which this inspection was completed.

This report.shall include:

! (a) Nuder and extent of tubes inspected.

I

( (b) Location and percent of wall-thickness penetration for each

! indication of an imperfection.

!- (c) Identification of tubes plugged.

]

4.10-4a 06/11/85 5780L-SFN

MAINE YANNEE ATOMIC POWrl COMPANY Basis: The Surveillance Requirements for inspection of the steam generator tubes ensure that the structural integrity of this portion of the RCS will be maintained. The program for inservice inspection of steam 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 maintain surveillance of the conditions of the tubes in the event that there is evidence of mechanical damage or i 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 characterizing the nature and cause of any tube degradation so that corrective measures .

can be taken. l 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 and 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.

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 imperfactions exceeding the plugging limit of 404 of the tube nominal wall thickness. Steam generator tube inspections of operating plants have demonstrated the capability to reliably detect degradation that has penetrated 20% of the original tube wall thickness.

]

In the past, Maine Yankee as well as other licensees have experienced ]

steam generator tube degradation in specific localized areas. The ,

exception permits inspecting 100% of the localized area and a .

representative sample of remaining tubes, when degradation of tubes ]

in the localized area would otherwise cause the inspection results to ]

be classified C-3. ]

/

4.10-6 06/11/85 5780L-SEN

TAIR.E A,10-2 STEAM EPERATOR TLEE. INSPECTION ,

l i iI Ii I I lst SAwtE INSPECTION ll 2nd SAWLE INSPECTION l1 3rd SAWLE INSPECTION l l ll I1 -1 I . I I il i 11 I I l Sample Size l Result 1 Action RegJired iI Result i Action Required iI Result i Action Required I ll I I i 11 l I I ll I i i 11 l 1 l l A minimum of l C-1 1 None !I WA I WA Il WA 1 WA i l ISK Times l l 11 1 11 I I ))-

Iper S. G. l l I ll l l , C-2 Plug defective tubes !l C-1 i None iI WA I WA I I iand inspect additionalil l Plug defactive tubes ll C-1 1 None l l l 12SE tubes in this ll C-2 I and inspect additional lI c-z I Plug aerective tunes I ));

l I

1 I

l IS. G.

l Il ll i ASE tubes in this l-S. G.

ll lI C-3 l Perform action for

-l C-3 result of first I

l

))'

! 1 l l ll 1 II I sample i I I I II l Perform action for iI . I l l l l 11 C 1 C-3 result of first 11 WA l WA I I I I ll I sam le ll l l l l C-3 l Inspect all tubes in Ii All other I ii i i i i i this S.G., plug de- 11 S.G.s are ~ l None i 1. WA I WA I I I l fective ttbes and ll C I ll l l l l l inspect 2SE tubes !I Some S.G.sl Perform action for ll l 1 )), '

I l [ each S.G. ll C-2 but nol C-2. result of second ll N/A I WA l I I I II additionall sample iI l l 1 I I Report to leC as 11 S.G. are 1 ll l l )) ;,

I I I necessary pursuant ll C-3 I ll l 1 ))'

l l l to Specification iI Additionali Inspect all tubes in iI I l )) i I I I 5.6 11 i each S.G. and plug 11 I I ))i i i i li i defective tubes. II I I l l l ll l 11 WA l WA I I ll Report to PHC as l l , ,

l ll e nry pursuant to I l ..

l l 1 ll 1 Specification 5.C il l I ))

S = 3 Wn Percent where N is the number of steam generators in the unit, and n is the number of steam generators inspected ))

during an inspection

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