ML20217F970

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Proposed Tech Specs,Incorporating ARC for Axial Primary Water Stress Corrosion Cracking at Dented Tube Support Plate Intersections
ML20217F970
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 10/14/1999
From:
TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20217F959 List:
References
NUDOCS 9910210142
Download: ML20217F970 (33)
v • d • e


Text

1

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REACTOR COOLANT SYSTEM C SURVEILLANCE REQUIREMENTS (Continued)

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3. A tube inspection (pursuant to Specification 4.4.5.4.a.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.
4. Indicationa left in service as a result of application of the I tube support plate voltage-based repair c'riteria shall be R226 inspected by bobbin coil probe during all future r efueling l outages, j
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 l '

those areas of the tube sheet array where tubes with imperfections were previously found.

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

NOTE: Tube degradation identified in the portion cf the tube that l is not a reactor coolant pressure boundary (tube end up to R193

)

the start of the tube-to-tubesheet weld) is excluded from the I

Result and Action Required in Table 4.4-2.

d. Implementation of the steam generator tube / tube support plate l repair criteria requires a 100 percent bobbin coil inspection for j

'- hot-leg and cold-leg tube support plate intersections down to the R226 3 j

lowest cold-leg tube support plate with known outside diameter M#g,/ stress corrosion cracking (CDSCC) indications. The determination

,["' /) of the lowest cold-leg tube support plate intersections having ODSCC indications shall be based on the performance of at least a 20 percent random sampling of tubes inspected over their full ,

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

Catecorv Inscection Results

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

C-2 _One or more tubes, but not more than it of the total tubes inspected are defective, or between j 5% and 10% of the total tubes inspected are degraded tubes. l C-3 More than lot of the total tubes inspected are j degraded tubes or more than it of the inspected tubes are defective.

Note: In all inspections, previously degraded tubes must exhibit l significant (greater than 10%) further wall penetrations to 4

, be included in the above percentage calculations.

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~.. R226 9910210142 991014 PDR ADOCK 05000327 P PDR April 9, 1997 3/4 4-7 Amendment No. 189, 214, 222 M@@@ TEM - UNIT 1 _

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-REACTOR' COOLANT SYSTEM A

WhSURVEILLANCE REQUIREMENTS ,(Contih'. tied) ~

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L 4 '. 4 , 5 . 4 .Acceotance Criteria -~

!a. . Asyused in this Specification:

1. -Imcerfection'means an exception to the dimensions, finish or contour of .a tube from that required by (abrication drawings

-or specifications.. Eddy-current cesting:'endications below 20%:of the nominal tube wall thickness, if detectable, may L the considered as imperfections.

2. 'Decradation means a service-induced cracking, wastage, wear

.. or general corrosion occuring or either'inside or outside of a tube.

-3. Decraded Tube means a tube containing imperfections greater than or equal t6 20%3 of the nominal wall thickness caused by degradation.

'4. -t Decradation means the percentage of the tube wall thickness affected or removed by degradation.

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5. Defect means an imperfection of such severity that it exceeds l the plugging limit.. A tube containing a defect isidefective. ,

ya 6. Pluccine Limit means the imperfection depth at or beyond X ' which the tube shall be removed from service and is equal to i V, ~

'40% of the nominal tube wall thickness. Plugging limit does R193 {

%- not apply to that portion of the tube that is. net within the pressure boundary of the reactor coolant system (tube end up .

to the start of. the tube-to-tubesheet weld) . This definition >

~does not apply to tube support plate intersections if the R226

, voltage-based repair-criteria are being applied. Refer to 4.4.5.4.a.10 for the repair limit applicable to.these intersections.' 4

.7 Unserviceable describes the condition of a tube if it leaks. ;

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'or contains a defect large.enough to affect its structural  :((

' integrity in.the event of an Operating Basis Earthquake, a loss-of-coolant accident, or a steam line or feedwater line break as specified_in 4.4.5.3.c, above.

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-8. ' Tube Insoection means an inspection of the steam generator.

tube f rom the- point of entry (hot leg side)' completely around o 1

-the U-bend to the. top support of the cold leg. ,_

.9 . Eraservice Insoection means a tube inspection of the full length of orch tube in each steam generator performed by eddy current techniques prior to service establish a baseline con-

. 'dition of the tubing. This-inspection shall be performed prior'to initial POWER' OPERATION using the equ'ipment and

? techniques' expected to<be used during subsequent inservice inspections.

10. ' Tube Succort Plate Pluccina Limit is used for the disposition of an~ alloy 600 steam generator tube for continued service R226

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'thatiisLexperiencing predominately axially oriented outside Ediameter stress corrosion cracking confined within the I.

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April 9, 1997 Amendment No. 189, 214, 222 3/4 4-9 SEQUOYAHJ, UNIT'1

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s REACTOR COOL, TNT SYST1D4

g SURVEILLANCE REQUIREMENTS (Continued)

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'where:.

Vvat -- . upper voltage repair limit Vutt ' = lower voltage repair limit Vuunt : = mid-eycle upper'valtage repair limit based on time into cycle "s Vuug - mid-cycle l'ower voltage repair limit based on vuuac'and time into cycle at = ~ length of time since last scheduled inspection during which Vuac and V tac were implemented CL = cycle length (the time between two scheduled steam generator inspections)

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structural limit vol: age Gr = average growth rate per cycle length R226

., NDE = 95-percent cumulative probability allowance for nondestructive examination uncertainty (i.e., a ,

value of 20-percent has been approved by NRC)

-- Implementation of these mid-cycle repair limits should follow the same approach

as in1TS 4.4.5.4.a.10.a. 4&4.5.4.a.10.b, and 4.4.5.4.a.10.e.

"~ Note 1: . The lower voltage repair limit is 1.0 volt for 3/4-inch ' diameter tubing or 2.0. volts for 7/8-inch diameter tubing.

Mote 2: 'The upper voltage. repair limit is calculated according to the methodology in GL 90-05 as supplemented. vuat may differ at the s- TSPs.and-flow distribution baffle.

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.l. april 9, 1997 1

3/4 4-9b Amendment No, 189, 214, 222

.SEQUOYAH -1 UNIT l1-

REACTOR CCOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continued)

b. The steam generator shall be determined OPERA 3LE 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 Recorts

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a. Following each inservice inspection of steam generator tubes, the number of tubes plugged in each steam generator shall be reported to the Commission within 15 days,
b. The complete results of the steam generator tube inservice inspection shall be submitted to the Ccmmission in a Special Report pursuant to specification 6.9.2 within 12 months following completien of the inspection. This Special Report shall include:
1. Number and extenb of tubes inspected.

2., Location and percent of wall-thickness penetration for each indication of an imperfection.

3. Identification cf tubes plugged.
c. Results of steam generator tube inspections which fall into lR40 ',

Category C-3 shall be reported pursuant to Specification 6.6.1 prior to resumption of plant operation. The written followup of this report shall provide a description of investigations conducted ..

to determine cause of the tube degradation and corrective measures taken to prevent recurrence. ,

, /

d. For implementation of the voltage-based repair criteria to tube support plate intersections, notify the staff prior to returning the steam generators to service should any of the following conditions arise:
1. If estimated leakage based on the projected end-of-cycle (or if not practical using the actual measured end-of-cycle) voltage distribuPion exceeds the leak limit (determined from the licensing basis dose calculation for the postuAated main steam line break) for the next operating cycle.

R226

2. If circumferential crack-like indications are detected at the tube support plate intersections.
3. If indications are identified that extend beyond the confines of the tube support plate.
4. If indications are identified at the tube support plate elevations that are attributable to primary water stress corrosion cracking.
5. If the calculated conditional burst probability based on the projected end-of-cycle (or if not practical, using the actual4 measured end-of-cycle) voltage distribution exceeds 1 X 10 ,

not'fy the NRC and provide an assessment of the safety significance of tne occurrence.

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D j April 9, 1997 3/4 4-10 Amendment No. 36, 214, 222 SEQJOYAH - UNIT 1

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The mid-cycle equation of SR 4.4.5.4.a.10.e should only be used during ='

unplanned inspection in which eddy current data is acquired for indications at {

i tho tube support plates.

SR 4.4.5.5 implements several reporting requirements recommended by GL 95-05 for situations which ERC wants to be notified prior to returning the R226 S/Ga to service. For SR 4.4.5.5.d., Items 3 and 4, indications are applicable only where alternate plugging criteria is being applied. Per the purposes of this reporting requirement, leakage and conditional burst probability can be ecleulated based on the as-found voltage distribution rather than the projected cnd-of-cycle voltage distribution (refer to GL 95-05 for more information) when it is not practical to complete these calculations using the projected EOC voltage distributions prior to returning the S/Gs to service. Note that if lerkage and conditional burst probability were calculated using the measured EOC voltage distribution for the purposes of addressing GL Sections 6.a.1 and j 6.n.3 reporting criteria, then the results of the projected EOC voltage distribution should be provided pep GL Section 6.b(c) criteria.

Wastage-type defects are unlikely with proper chemistry treatment of the c;condary 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 exceeding the repair R226 limit defined in Surveillance Requirement 4.4.5.4.a. The portion of the tube  !

that the plugging limit does not apply to is the portion of the tube that is I not within the RCS pressure boundary _(tube end up to the start of the tube-to- R193 ., f' tubasheet weld) . The tube end to tube-to-tubesheet weld portion of the tube dono not affect structural integrity of the steam generator tubes and therefore (

indications found in this portion of the tube will be excluded from the Result ,_

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and Action Required for tube inspections. It is expected thtt any indications i !

that extend from this region will be detected during the scheduled tube '#

t intpections. 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.

Tubes experiancing outside diameter stress corrosion cracking within the R226 thickness of the tube support plate are plugged or repaired by the criteria of 4.4.5.4.a.10.

Rhene'ver the results of any steam generator tubing inservice inspection fall into Category C-3, these results will be promptly reported to the Commission pursuant to Specification 6.6.1 prior to resumption of plant opera- R40 tion. Such cases will be considered by the Commission en a case-by-case basis cnd may result in a requirement for analysis, laboratory examinations, tests, cdditional eddy-current inspection, and revision of the Technical Spncifications, if necessary.

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.p%62 T LE R226 April 9, 1997 ,

SEQUOYAH - UNIT 1 B 3/4 4-4 Amendment No. 36, 189, 214, 222 (%-

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l REACTOR COOLANT SYSTEM

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SURVEILLANCE REQUIREMENTS (Continued) l l

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l. All nonplugged tubes that previously had detectable wall pene-trations (greater than 20%) l
2. Tubes in those areas where experience has indicated potential problems.
3. A tube inspection (pursuant to Specificaticq,4.4.5. .a.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 l selected and subjected to a tube inspection.

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4. Indications left in service as a result of application of the tube support plate voltage-based repair criteria shall be R213 inspected by bobbin coil probe during all future refueling l outages. ,

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c. The tubes selected as'the second and third samples (if required by i Table 4.4-2) during each inservice inspection may be subjected to a I l

partial tube inspection provided-l

1. The tubes selected for these samples include the tubes from

. those areas of the tube sheet array where tubes with imperfections were previously fouad.

2. The inspections include those portions of the tubes where ,

imperfections were previously found. I hote: Tube degsadation identified in the portion of the cube that 'R181 N _- is not a reactor coolant pressure boundary (tube end up to the start of the tube-to-tubesheet weld) is excluded from the Result and Action Required in Table 4.4-2.

d. Implementation of the steam generator tube / tube support plate repair

<~N- criteria requires a 100 percent bobbin coil inspection for hot-leg *

- and cold-leg tube support plate intersections down to the lowest R213

((hyhbb/ cold-leg tube support plate with known cutside diameter stress g corrosion cracking (ODSCC) indications. The determination of the lowest cold-leg tube support plate intersections having ODSCC indications shall be based on the performance of at least a 20

\wsg. percent random sampling of tubes inspected over their full length.

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

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

R213 April 9, 1997

. SEQUOYAH - Unit 2 3/4 4-11 Amendment No. 181, 211, 213

REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continued)

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4.4.5.4 Accentance criteria

a. As used in this Specification:
1. Imrerfection 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 con-sidered as imperfections.
2. Decradation means a service-induced cracking, wastage, wear or general corrosion occurring on either inside or outside of a tube.
3. Deeraded Tube means a tube containing imperfections greater than or equal to 20% of j the nominal wall thickness caused by degradation.
4. t Deeradation 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. Pluccine Limit means the imperfection depth at or beyond which the tube shall be removed from service and is equal to 40% of the nomincl tube wall thickness. Plugging limit does not apply to that portion of the tube that is not witbin the pressure R181 ,

( boundary of the reactor coolant system (tube end up to the start {

-- of the tube-to-tubesheet weld). This definition does not apply j to tube support plate intersections if the voltage-based repair R213 l criteria are being applied. Refer to 4.4.5.4.a.10 for the

, repair limit applicable to these intersections. rf ___ ,,

7. Unserviceable describes the condition of a tube if it leaks or ][sM2LC7' ,

contains a defect large enough to affect its structural integrity in the event of an Operating Basis Earthquake, a loss- [3 of-coolant accident, or a steam line or feedwater line break as -

specified in 4.4.5.3.c, above.  !

8. Tube Insoection 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.

9., Preservice Inseection means an inspection of the full length of each tube in each steam generster performed by eddy current techniques prior to service to establish a baseline condition 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.

10. Tube Sunoort Plate Plucaine Limit is used for the disposition of an alloy Goo steam generator tube for continued service that is R213 experiencing predominately axially oriented outside diameter stress corrosion cracking confined within the thickness of the April 9, 1997 3/4 4-13 Amendment No. 181, 211, 213 SEQUOYAH - UNIT 2

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REACTOR COOLANT SYSTEM I m SURVEILLANCE REQUIREMENTS (Continued) k;t d

"" #Y where:

Vunt = upper voltage repair limit Vat = lower voltage repair limit vuunt - mid-cycle upper voltage recair limit based on time N

into cycle Vaug = mid-cycle lower voltage repair limit based on V uunt and time into cycle l

length of time since last. scheduled inspection durirJ7 R213 At =

j which Vatu and V ug were implemented 1 CL = cycle length (the time between two scheduled steam generator inspections)

Vst = structural limit voltage Gr = average growth rate per cycle length 1 NDE = 95-percent cumulative probability allowance for .

nondestructive examination uncertainty (i.e., a value )

of 20-percent has been approved by NRC) 1 1

~

Implementation of these mid-cycle repair limits should follow the same approach ]

j as in TS 4.4.5.4.a.10.a, 4.4.5.4.a.10.b, and 4.4.5.4.a.10.c. <

Note 1: The lower voltage repair limit is 1.0 volt for 3/4-inch diameter 1 e.ubing or 2.0 volts for 7/8-inch diameter tubing.

Note 2: The upper voltage repair limit is calculated according to the  !

methodology in GL 90-05 as supplemented. Vat may dif fer at the TSPs 7'

2.gjgg , and flow distribution baffle. .

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ss. The steam generator shall be determined OPERABLE af ter completing the I

b.

corresponding actions (plug all tubes exceeding the plugging limit ,

and all tubes containing through-wall cracks) required by l Table 4.4-2.

- l 4.4.5.5 Recorts

a. Following each inservice inspection of steam generater tubes, the  ;

number of tubes plugged in each steam generator shall be reported to  ;

the Commission within 15 days.

b. The complete results of the steam generator tube inservice inspection shall be sabmitted to the Commission in a Special Report pursuant to

- Spe-ification $.9.2 within 12 months following the completion of the inspection. This Special Report shall include:

1. Number and extent of tubes inspected. I R213 April 9, 1997

' 3/4 4-14a Amendment No. 28, 211, 213 l SEQUOYAH - UNIT 2 s

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-- REACTOR COOLAN*:' SYSTEM

SURVEILLANCE REQUIREMENTS'(Continued)'

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'2. Location.aind percent'of wall-thickn'ess penetration for each indication of an imperfection.

3.- ~ Identification of tubes plugged.

.c. Results'ef steam generator tube inspections which fall into Category R2S C-3 shall be reported pursuant to Specification 6.6.1 prior-to resumption of plant operation. The written followup of this report shall provide a description of investigations conducted to determine cause of the tube degradation and corrective me.asures taken'to prevent recurrence.

d. For implementation of the voltage-based repair criteria to tube support plate intersections, notify the staff prior to returning the

-steam generators to service should any of the following conditions arise:

1. Ifestimatedleakahebasedontheprojectedend-of-cycle (or if not practical using the actual measured end-of-cycle) voltage distribution exceeds the leak limit (determined from the licensing basis dose calculation for the postulated main steam R213 line break) for the next. operating cycle.
2. If circumfe: aal crack-like indications are detected at the tube support plate intersections,
3. If indications are identified that extend beyond the confines of the tube support plate.
I i
4. If indications are identified at the tube support plate s ,,,

elevations that are attributable to primary water stress corrosion cracking.

  • . S. If the calculated conditional burst probability based on the projected end-of-cycle (or if not practical, using the actual4 .

measured end-of-cycle) voltage distribution exceeds 1 X 10 ,

notify the NRC and' provide an assessment of the safety significance of the occurrence.

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R213 1 l

. April 9, 1997

SEQUOYAH,- UNIT 2 3/4 4-14b Amendment No. 29, 211, 21,,3 .,

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} REACTOR COOLANT SYSTEM

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BASES Y.

where Vca represents the allowance for flaw growth between inspections and veg represents the allowance for potential sources of error in the measurement of the bobbin coil voltage. 'Further discussion of the assumptions necessary to determine 1the voltage repair limit are discassed in GL 95-05.

The mid-cycle equation of SR 4.4.5.4.a.10.e should only be used during unplanned inspection in.which eddy current' data'is acquiredsfor indications at R213 the tube support plates.

SR 4.4.5.5 implements several reporting requirements recommended by GL 95-05 for situations'which NRC wants to be notified prior to returning the S/Gs to service. .For SR 4.4.5.5.d.,. Items 3 and 4, indications are applicable-only where alternate plugging criteria is being applied. For the purposes of this reporting-requirement,- leakage and conditional burst probability can be calculated based on the as-found voltage distribution rather than the projected end-of-cycle voltage distribution.(refer to GL 95-05 for more information) when it is not practical to complete these calculations using the projected EOC voltage distributions prior to returning the S/Gs to service. Note that if leakage and conditional burst probability were calculated using the measured EOC voltage distribution for the purposes of addressing GL Sections 6.a.1 and

.6.a.3 reporting criteria, then the results of the projected EOC voltage

' distribution should be provided per GL Section 6.b(c) criteria.

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 exceeding the repair 3 '

limit defined in Surveillance Requirement 4.4.5.4.a. The portion of the tube \

that the plugging limit does not apply to is the portion of ths tube that is not within the RCS pressure boundary (tube end up to the start of the tube-to-tubesheet weld) . . The tube end to tube-to-tubesheet weld portion of the tube does.not affect structural integrity of the steam generator tubes and therefore

. indications found in this portion of the tube will be excluded from the Result and Action-Required for tube inspections. It is expected that any indications ,

that extend from'this region.will be detected during the scheduled tube inspections. 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.

Tubes experiencing outside diameter stress corresion cracking within the j thickness of the tube support plate are plugged or repaired by the criteria of R213 j 4.4.5.4.a.10.

Whenever the results of any steam generator tr.bing inservice inspection j j

fall'into Category C-3, these results will be promptly reported to the Commission pursuant to Specification 6.6.1 prior to resumption of plant j operation. Such cases will be cousidered by the Co amission on a case-by-case '

basis and may result in a requirement for analysis, laboratory examinations, tests, additional eddy-current inspection, and revision of the Technical o Specifications, if necessary.

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April 9, 1997

,SEQUOYAH'- UNIT 2 B 3/4 4-3a- Amendment No. 181, 211, 213

3,.

Technical Specification Change 99-12 Sequoyah Nuclear Plant Units 1'and 2

-INSERT PAGE INSERT A

e. Inspection of dented tube support plate intersections will be performed in accordance with WCAP 15128, Revision 1, dated' August.1999.

INSERT B

.-This definition :does not apply for Lgreater than .or: equal to' 40 percent deep 1 indications ofLaxial PWSCC located'within the tube support plate, PWSCC indicationsDlocated within and extending outside.the' tube support; plate, or PWSCC indications located at the. edge.of the tube support l plate. Refer to 4.4.5.4.a.11 for the. repair limits applicable.to these intersections.

INSERT C

.11. Primary Water Stress Corrosion Cracking (PWSCC) Tube Support Plate PluggJng Limit is used~for the disposition.of an Alloy 400 steam generator tube for continued service that is ,

experiencing predominantly cxially oriented-PWSCC at dented i tube. support plate intersections'as described in WCAP 15128, J Revision 1, dated August 1999. l l

_ INSERT?D l

e. LFor implementation.of the depth-based repair. criteria for axial,PWSCC at dented TSPs,- the results of the condition 1 monitoring and operational assessments will be reported to the,NRC within 120-days following completion of the

~

inspection. The report will include tabulations of
indications found.inJthe inspection, tabulations of tubes repaired and leftLin cervice under-the ARC, and growth rate 1 distributions for indications'found in the inspection as well I as'the' growth distributions 1used to establish the tube' repair limits . . Any corrsctive! actions found necessary in the event

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-that condition monitoring;iequirements are not met will be

identified in the' report.

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t A

V INSERT E The steam generator tube repair limits for primary water stress corrosion. cracking (PWSCC) of SR 4.4.5 represents a steam generator tube alternate repair criteria for greater than or

' equal to 40 percent deep PWSCC indications within the tube ,

support plate, PWSCC indications within and extending outside the I tube support plate, or PWSCC indications located at the edge of the tube support plate. The repair-bases for PWSCC are not l

. applicable to other types of localized tube wall degradation located at the' tube-to-tube support plate intersections.

The ARC includes, completion of a condition mon 3.toring assessment to determine the end-of-cycle (EOC) condition of the tube bundle.

Next, an operational assessment is completed to determine the need for tube repair on a forward-fit basis. The ARC is cased on the use of crack. depth profiles obtained from Plus Point analyses. Burst pressures are calculated from depth profiles by searching the total crack length for the partial length that

- results in the lowest burst pressure. The' repair bases for PWSCC at dented TSP' intersections is obtained by projecting the crack profile to the end of the next operating cycle and determining if the projected profile meets the burst margin requirements of

' WCAP-15128, Revision 1, dated August 1999. The following provides the limits and bases for repair established in the WCAP analyses:

Maximum Depth Repair Limit The repair limit for maximum depth is established to obtain a low likelihood of SLB leakage for the operational assessment. The limit is based on ensuring against through-wall degradation at 95 percent confidence. The repair limit for maximum depth is obtained by reducing through-wall penetration by 2 percent for breakthrough, by NDE uncertainties on maximum depth at 95 percent confidence and by growth of maximum depth at 95 percent cumulative probability.

Note: The maximum depth repair limit is dependent upon growth rate and cycle length. Repair limits are updated when new growth data are obtained and when cycle lengths and/or operating temperatures are changed.

Crack Length Limits b The crack length limit is defined as 0.60 inch from the centerline of the TSP.

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l Note: The 0.60 inch. length limit allows a crack to begin the

. cycle with a length of 0.225 inch outside the TSP (TSP is 0.375 inch F 0.225 inch = 0.60 inch). The 0.225 inch allows a margin of 0.275.ir.ch for potential growth to 0.5 inch outside the TSP which bounds expected growth at 95 percent confidence. This maximum length limit is provided to limit potential freespan lengths and provide significant margins against leakage and burst. The crack left in service must alsc satisfy the following operational assessment repair bases.

Operational Assessment Repair Bases If the indication satisfies the above maxi,num depth and total length requirements, the repair bases is then obtained by projecting the crack profile to the end of the next operating cycle and determining the burst pressure for the projected profile. The burst pressure is compared to the burst margin requirements in WCAP-15128, Revision 1, dated August 1999.

{

Separate burst analyses are required for the total crack length {

and'the length outside the TSP due to differences in burst margin j requirements. If the projected EOC burst margin requirements are j satisfied, the indications'will be left in service.

j 1

The results of the condition monitoring and operational assessments will be reported to the NRC within 120 days following completion of the inspection.

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'*f ENCLOSUPI'3 TENNESSEE VALLEY AUTHORITY SEQUOYAH-NUCLEAR PLANT (SQN)

UNITS 1 AND 2 ,

PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE REVISED PAGES k

I, AFFECTED'PAGE LIST J J

Unit 1 3/4 4-7 3/4 4-9 3/4 4-9a 3/4 4-9b 3/4 4-10 i 3/4 4-10a B 3/4 4-4 B 3/4 4-4a B 3/4 4-4b' B 3/4 4-4c Unit 2 3/4 4-11 3/4 4-13 ,

3/4 4-14 l 3/4.4-14a I 3/4 4-14b 3f'4. 4-14c B 3/4.'4-3a i B 3/4 4-3b I l

l II. REVISED PAGES See attached.

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REACTOR CCOLANT SYSTEM i SURVEILLANCE REQUIREMENTS (Continued)

3. A' tube inspection (pursuant to Specification 4.4.5.4.a.8) shall be performed on each selected tube. If any selected i tube does not permit the passagu of the eddy current probe '

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

4. Indications left in service as a result of application of the tube support plate voltage-based repair criteria shall be R226 inspected by bobbin coil probe during all future refueling outages.
c. The tubes selected as'the second and third samples (if required by l 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 previously found.
2. The inspections include those portions of the tubes where imperfections were previously found.

NOTE: ' Tube degradation identified in the portion of the tube that is not a reactor coolant pressure boundary (tube end up to R193 the start of the tube-to-tubesheet weld) is excluded from the Result and Action Required in Table 4.4-2.

d. Implementation of the steam generator tube / tube support plate repair criteria requires a 100 percent bobbin coil inspection for hot-leg and cold-leg tube support plate intersections down to the R226 lowest cold-leg tube support plate with known outside diameter stress corrosion cracking (ODSCC) indications. The determination of the lowest cold-leg tube support plate intersections having  ;

ODSCC indications shall be based on the performance of at least a 20 percent random sampling of tubes inspected over their full length,

e. . Inspection of dented tube support plate intersections will be

' performed in accordance with WCAP 15128, Revision 1, dated August 1999.

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

Catecorv Insoection Results C-1 Less than 5%.of the total tubes inspected are degraded tubes and none of the inspected tubes j 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 j degraded tubes.

C-3 More than 10% of the total tubes innpected are degraded tubes or more than 1% of the inspected 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. l R226

, SEQUOYAH - UNIT 1 3/4 4-7 Amendment No. 189, 214, 222, )

j

Y REACTOR COOLANT SYSTEM I

SURVEILLANCE REQUIREMENTS (Continued) 4.4.5.4 Accentance Criteria i I

a. As used in this Specification: I i
1. Ig _fection means an exception to the dimensions, finish or l ce .our of a tube from that required by fabrication drawingo {

or specifications. Eddy-cur ent testing indications below 20% of the nominal tube wall thickness, if detectable, may l be considered as imperfections. l

2. Degradation means a service-induced cracking, wastage, wear i or general corrosion occuring or either inside or outside of j a tube. )

1

3. Decraded Tube means a tube containing imperfections greater than or equal to 20% of the nominal wall thickness caused by degradation.
4. t Dearadation means the percentage of the tube wall thickness j affected or removed by degradatica. t
5. Defect means an imperfection of such severity that it exceeds the plugging limit. A tube containing a defect is defective.
6. Pluccina Limit means the imperfection depth at or beyond which the tube shall be removed from service and is equal to 40% of the nominal tube wall thickness. Plugging limit does R193 not apply to that portion of the tube that is not within the pressure boundary of the reactor coolant system (tube end up to the start of the tube-to-tubesheet weld). This definition does not apply to tube support plate intersections if the R226 voltage-based repair criteria are being applied. Refer to 4.4.5.4.a.10 for the repair limit applicable to these intersections. This definition does not apply for greater than or equal to 40 percent deep indications of axial PWSCC located within the tube support plate, PWSCC indications located within and extending outside the tube support plate,  ;

or PWSCC indications located at the edge of the tube support {

plate. Refer to 4.4.5.4.a.11 for the repair limits i applicable to these intersections.

7. UnggIv,_igeabla 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 Earthquake, a i loss-of-coolant accident, or a steam line or feedwater line  !

break as specified in 4.4.5.3.c, above, j 1

8. Tube Insoection means an inspection of the ster generator I tube from the point of entry (hot leg side) completely around j the U-bend to the top support of the cold leg.

J

9. Preservice Inspection means a tube inspection of the full I length of each tube in each steam generator performed by eddy current techniques prior to service establish a baseline con- )

dition of the tubing. This inspection shall be performed j prior to initial POWER OPERATION using the equipment and 1 techniques expected to be used during subsequent inservice inspections.

SEQUOYAH - UNIT 1 3/4 4-9 Amendment No. 189, 214, 222, L- I

. ?? l

[' l R[39, TOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continued)

10. Ipbe supoort Plate Pluccina Limit is used for the disposition l of an alloy 600 steam generator tube for continued service that is experiencing predominately axially oriented outside diameter stress corrosion cracking confined within the thickness of the tube support plates. At tube support plate  !

intersections, the plugging (repair) limit is based on maintaining steam generator tube serviceability as described below:

a. Steam generator tubes, whose degradation is attributed to outside diameter stress corrosion cracking within the bounds of the tube support plate with bobbin voltages less than or equal to the lower voltage repair limit -(Note 1) , will be allowed to remain in survice,
b. Steam generator tubes, whose degradation is attributed to outside diameter stress corrosion cracking within the bounds of the tube support plate with a bobbin voltage greater than the lower voltage repair limit (Note 1), will be repaired or plugged, except as noted in 4.4.5.4.a.10.c below,
c. Steam generator tubes, with indications of potential degradation attributed to outside diameter stress corrosion-cracking within the bounds of the tube support plate with a bobbin voltage greater than the j lower voltage repair limit (Note 1), but less than or R226 .

equal to upper voltage repair limit (Note 2), may remain in service if a rotating pancake coil inspection does not detect degradation. Steam generator tubes, with indications of outside diameter stress corrosion- ,

cracking degradation with a bobbin coil voltage greate* I than the upnar voltage repair limit (Note 2) will be l plugged or ro ired. l

d. Not applicab2e to SQN. j
e. If an unscheduled mid-cycle inspection >s performed, the following mid-cycle repair limits apply instead of  ;

the limits identified in 4.4.5.4.a.10.a. j 4.4.5.4.a.10.b, and 4.4.5.4.a.10.c.

The mid-cycle repair limits are determined from the following equations: j l

Vst

' YMURL

  • 1.0+NDE+Gr CL (CL-At)

Vuta=Vuunt- (Vuut-Vog)

April 9, 1997 SEQUOYAH - UNIT 1 3/4 4-9a Amendment No. 189, 214, 222

'Kp'y);g + 2 .

g s

.e ' w ,; *, ,

p(,. p " yp-

~

ha~' M;p'

^

i

. ; PJMIQE_,QQQLANT SYSTEM fSURVEILLANCE ltEQUIREMENTS (Continued)

.v-== r=== w - r.==_w m -m -

< y.' 5 .

O wherei:

qq y TVNn - = upper voltage repair limit

' " " l lower volt' age repairi limitL Vt ke < z =

}

.,~  :. Vwvut9 - =- . .mid-cycle uppor voltage repair! limit based on.

4

< time into cyclo- i:  ;

' Vutn._ '

?mid-cycle lowergvoltage repair limit based on-  !

.Vute and time into cycle- 1 s . . ,.

.at J = '. tiength of" time since last scheduled inspection during which Vun and Vm were implemented-L cL- .. cycle length (the time between two scheduled steam generator inspections)'

.- V3 c =t -structural limit < voltage Grs '= average growth rate per cycle ' ngth R226

.NDE. ' =- .95-percent cumulative probability allowance for- I nondestructive" examination uncertainty (i.e.i a J i ;, < value' of :20-percent has been approved by NRC) .  !

.i

. Implementation of these. mid-cycle repair: limits . should follow the . same approach .

. [as. . in TS 4 . 4 . 5. 4 . a .10 '. a , - 4 /4 ,5. 4 a .10. b, ' and : 4 .'4 . 5. 4 . a .10. c . 1 0

Note 1: The lower voltage repair limit is 1.0 volt for 3/4-inch diameter l tubing or 2.0 volts'for 7/8-inch diameter tubing, j The upper voltage repair limit'in calculated according to the-

)

Note 2: i methodology in:GL 90-05.as supplemented. Von may differ at the. l TSPs and flow' distribution baffle; I J

,1

11. Primarv Water St;Igse Corrogl2n. Crackinc .[PWSCO) Tube Succort -)

Elate Pluccina Limit is used for the -disposition of an Alloy 600 steam generator tube for continued' service ths.t is

' experiencing predominantly axially oriented PWSCC at dented. .

tube support plate intersections as described in.WCAP 15128, f Revision 1, dated August 1999. )

i 1

i i

1 i

> I l

.,l.

- t >

LSEQUOYAH UNIT 1 -'- 3/4'4-9b Amendment No, 189, 214, 222, if i

L-

~ x  ;

,y* '! '

/ W #

  • d

. REACTOR' COOLANT SYSTEM

SURVEILLANCE REQUIREMENTS (Continued au A C
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. Dilowing each inservice inspection of steam generator tubes, the number of tubes plugged in each steam generator shall be reported to the Commission within 15 days.

lb. 1The' complete results of the steam generator tube inservice inspection shall be submitted to the Commission in'n Special Report

-pursuant to Specification 6.9.2 within 17. months following completion of the inspection.' This Special Report shall includat r 1. . Number and extent of. tubes inspected.

2. Location'and percent-of wall-thickness penetration for each

' indication of an imperfection.

.3. - I' dent.lfication of tubes plugged.

lR40

~L' 'c. Results of steam generator tube inspections which fall into Category C-3 shall be reported pursuant to Specification 6.6.1 prior to reaumption of plant operation. The-written followup of this report shall provide a description of investigations conducted ito determine cause of the tube degradation and corrective measures-taken to prevent recurrence.

d. For implementation of the voltage-based rer.ir criteria to tube support plate intersections, notity the sta .:. prior to returning the steam senerators to service should any of the following conditions arise
1. If estimated leakage based on the projected end-of-cycle (or if not practical using the actual measured end-of-cycle) voltage distribution exceeds the leak limit (determined from the. licensing basis dose calculation for the postulated main steam line break) for the next operating cycle. R226 ,

l

'2. If circumferential crack-like indications are detecte.1 at the tube support plate intersections.

3. If indications are identified that extend beyond the confines  !

of the. tube support plate.

4. If indications are identified at the tube support plate I elevations that are attributable to primary water stress l corrosion cracking. l
5. If the calculated conditional burst probability based on the i projected end-of-cycle '(or if not practical, using the actual l measured'end-of-cycle) voltage distributiou exceeds 1 X 10 4, j notify the NRC and provide an assessment of the saft.,ty significance of the occur: ence.

April 9, 1997 SEQUOYAH - UNIT 1 3/4 4-10 Amendment No. 36, 214, 222

)

,., , i-:T s

]

'l.. .

REACTOR COOLANT SYgIgi.)_ ,

y

' SURVEILLANCE , REQUIREMENTS ' (Continued) -

m aa,- ~...

e. -For-implementation of the~ depth-based repair criteria'for axini  !

PWSt.C at dented TSPs, Lthe results of the condition monitoring and l operational assesaments'will be reported to the NRC within 120 days i

following completion of %e'4.nspection. The report.will: include j

. tabulations of indicati.* e focud 2.n the-inspection,-tabulations of -

,' tubes. repaired and left, l'sarvice under the ARC, and growth rate distributions for indications found in the inspection as well as the growth distributions used to' establish the tube repair limits.

Any corrective actions found nececsary in the event that condition monitoring requirements'.'are not met will be identified in the report o.

/

i i

l

[,

(

SEQUOYAH.' UNIT 1 3/4 4'-10a< Amendment No.

. t j.,.T .'

. n .

i m ,#

r y4.

~

x..s-

  • lBEhW9R 2X1LANTA!M ,

a: '

"BASESS i a u-- , ,.w 1 l

'The'mid-cycle equatioo'of SR 4.4.5.4.a.10.e should only be used during

~

unplanned: inspection in which' eddy current data is acquired for indications at ,

the tubo support"platos..  !

SR'4.4.5.5 implementa. severs 1 reporting requirements recommended by

~

R226

GL'95-05 for situaticns which NRC wants to beLnotified prior to returning the .

J/Go'to service. .For SR 4.4.5.5.d,', Items 3 and 4,. indications are applicable

'only where alternate plugging. criteria is being applied; For the purpcses of 1

-thisLreporting requirement, leakage and conditional burst probability can be i calculated based'on'the as-found voltage distribution rather than the projected i

'end-of-cycle voltage distribution '(refer -to GL 95-05 for more information) when ~

I ituis not practical to complete these calculations uaing the projected EOC i voltage distributions prior to returning'the S/Gs to' service. Note that if leakage and conditional burst probabil.ity wars calculated uai:.g the measured EOC voltage distribution forfthe purposes of addressing GL Sections 6.a.1 and 6.a.3. reporting criteria, then the . results of the projected EOC voltage

! distribution should.be provided'per GL Section 6.b(c) criteria.

~ Wastage-type defects are unlikely 6ith proper chemistry treatment'of the

~

secondary. coolant. However, even if a' defect should develop in service,- it  !

will be-found during scheduled incarvice steam generator tube examinations.  ;

. Plugging will be required for alll cubes with imperfections exceeding the repair R226 l

' limit defined in-Surveillance Requirement:4.4.5.4.a. .The portion of the tube

-that the plugging, limit does not apply to is the portion of'the tube that is

~

not within the RCS pressure boundary (tube end up to the start of the tube-to- R193 ,

.tubesheet weld)'. The tube end to tube-to-tubesheet weld portion of.the tube i does not affect. structural integr.4ty of the steam generator tubes and therefore indications found in this portion of the tube will be excluded from the Result )

and Action. Required for tube inspections. It is expected that any indications l that extend =from this' region will be detected during the scheduler tube ,

l inspections; Steam generator tube inspections of operating plants have-  ;

demonstrated the capability to reliably detect degradation that has penetrated i 20% of the original tube wall thickness.

Tubes experiencing outside diameter stress corrosion cracking within the R226 thickness of the tube support plate are plugged or repaired by the criteria of 4.4.5.4.a.10.

The steam generator tube repair limits for primary water stress corrosion cracking (PWSCC) of SR 4.4.5 represents a steam generator tube alternate repair

. criteria for greater than or equal to 40 percent deep PWSCC indications within the. tube support plate, PWSCC indications within and extending outside the tube support plate, or PWSCC indications located at the edge of the tube support plate. -The repair bases for PWSCC are not applicable to other types of localized tube. wall degradation located at the tube-to-tube support plate intersections. l The ARC includes' completion of a condition monitoring assessment to determine.the'end-of-cycle (EOC) condition of the tube bundle. Next, an operational assessment is completed.to determine the need for tube repair on a forward-fit basis. -The ARC is' based on the use of crack depth profiles

-obtained from Plus Point analysesi Burst pressures are calculated from depth profiles byfsearching the total crack length for the partial length that

'results.in the lowest burst pressure. The repair bases for PWSCC at dented TSP

-intersections is obtained by projecting the crack profile to the end of the SEQUOYAH - UNIT 1 5 3/4 4-4 Amendment No. 36, 189, 214, 222,

1 l

. .. l REACTOR COOLANT SYSTEM BASES

_=

next operating cycle and determining if the projected profile meets the burst margin requirements of WCAP 15128, Revision 1, dated August 1999. The following provides the limits and bases for repair established in the WCAP analyses:

Maximum Depth Repair Limit The repair limit for maximum depth is established to obtain a low likelihocd of SLB leakage for the operational assessment. The limit is based on ensuring against through-wall degradation at 95 percent confidence. The repeir limit for maximum depth is obtained by reducing through-wall penetration by 2 percent for breakthrough, by NDE uncertainties on maximum depth at 95 percent confidence and by growth of maximum depth at 95 percent cumulacive probability.

Note: The maximum depth repair limit is dependent upon growth rate and cycle length. Repair limits are updated when new growth data are obtained and when cycle lengths and/or operating temperatures are changed.

Crack Length Limits The crack length limit is defined as 0.60 inch from the centerline of the TSP.

Note: The 0.60 inch length limit allows a crack to begin the cycle with a length of 0.225 inch outside the TSP (TSP is 0.375 inch + 0.225 inch - 0.60 inch). The 0.2?- inch allows a margin of 0.275 inch for potential growth to 0.5 inch outsid tne TSP which bounds expected growth at 95 percent confidence.

This maximum length limit is provided to limit potential freespan lengths and provide significant margins against leakage and burst. The crack left in service must also satisfy the following operational assessment repair bases.

Operational Assessment Repair Bases If the indication satisfies the above maximum depth and total length requirements, the repair bases is then obtained by projecting the crack profile to the end of the next operating cycle and determining the burst pressure for the projected profile. The burst pressure is compared to the burst margin requiremence in WCAP 15128, Revision 1, dated August 1999. Separate burst analyses are required for the total crack length and the length outside the TSP due to differences in burst margin requirements. If the projected EOC burst margin requirements are satisfied, the tube will be left in service.

The results of the condition monitoring and operational assessments will be reported to the NRC within 120 days following completion of the inspection.

Whenever the results of any steam generator tubing inservice inspection fall into Category C-3, these results will be promptly reported to the Commission pursuant to Specification 6.6.1 prior to resumption of plant opera- R40 tion. Such cases will be considered by the Commission on a case-by-case basis and may result in a requirement for analysis, laboratory examinations, tests, additional eddy-current inspection, and revision of the Technical

-Specifications, if necessary.

R226 SEQUOYAH - UNIT 1 B 3/4 4-4a Amendment No. 36, 189, 214, 222, i

i

---e p l$ Qh Q- 4 0

^f g k7 a-fewoOG 3/4.4.6 REACTOR COQLANT SYSTEM LEAKAGE y F

3/4.4.6.1 LEAKAGE DETECTION SYSTEMS _-s ___

The RCS leakage detection systems required by this specification are I provided to monitor and detect leakage from the Reactor Coolant Pressure

{

Boundary. These detection systems are consistent with the recommendations of Regulatory Guide 1.45, " Reactor Coolant Pressure Boundary Leakage Detection Systems," May:1973.

3/4.4.6.2 OPERATIONAL LEAKAGE ,

i Industry experience has shown that while a limited amount of leakage is i expected from the RCS, the unidentified portion of this leakage can be reduced I to a threshold value of less than 1 GPM. This threshold value is sufficiently J low to ensure early detection of additional leakage. (

i The surveillance requirements for RCS Pressure Isolation Valves provide {

~ added assurances of valve integrity thereby reducing the probability of gross j valve failure and consequent intersystem LOCA. Leakage from the RCS isolation i valves is IDENTIFIED LEAKAGE and will be considered as a portion of the allowed I limit.

The 10 GPM. IDENTIFIED LEAKAGE limitation provides allowance for a limited

]

amount of leakage from known sources whose presence will not interfere with the I detection of UNIDENTIFIED LEAKAGE by the leakage detection systems.

The CONTROLLED LEJJ  ; limitation restricts operation when the total flow supplied to the reactor lant pump seals exceeds 40 GPM with the modulating t valve in the supply line tally open at a nominal RCS pressure of 2235 psig.

This limitation ensures that in the event of a LOCA, the safety injection flow will not be less than assumed in the accident analyses.

The total steam generator tube leakage limit of 600 gallons per day for  !

all steam' generators and 150 gallons per day for any one steam generator will R226 minimize the potential for a significant leakage event during steam line break, l Based on the NDE uncertainties, bobbin coil. voltage distribution and crack l growth rate from the previous inspection, the expected leak rate following a steam line rupture is limited to below 8.21 gpm at atmospheric conditions and 70*F in the faulted loop, which will limit the ce.lculated offsite doses to within 10 percent of the 10 CFR 100 guidelines. If the projected and cycle distribution of crack indications results in primary-to-secondary leakage j greater than 8.21 gpm in the faulted loop during a postulated steam line break j event, additional tubes must be removed from service in order to reduce the l postulated primary-to-secondary steam line break leakage to below 8.21 gpm. l R241 The 150-gallons per day limit incorporated into :a 4.4.6 is more restrictive than the standard operating leakage limit and is intended to provide an additional margin to accommodate a crack which might grow at a greater than expected rate or unexpectedly extead outside the thickness of the tube support plate. Hence, the reduced leakage limit, when combined with an effective leak rate monitoring program, provides additional assurance that, should a significant leak be experienced,.it will be detected, and the plant i shut down in a timely manner.

PRESSURE BOUNDARY LEAKAGE of any magnitude is unacceptable since it may be indicative of an impending gross failure of the pressure boundary.

Therefore, the presence of any PRESSURE BOUNDARY LEAKAGE requires the unit to

,be promptly placed in COLD SHUTDOWN.

R226 November 17, 1998 SEQUOYAH - UNIT 1- B 3/4 4-4b Amendment No. 36, 189, 214, 222, 237

, I i

i

.dV

..f 't REACTOR COOLANT SYSTEM l

. BASES 3 /4 '. 4 '. 7 CHEMISTRY.

The< limitations on Reactor' Coolant System chemistry ensure that corrosion of the Reactor Coolant System is minimized and reduces the potential-for .

Reactor Coolant System leakage or failure due to stress corrosion. Maintaining- )

the chemistry within the Steady State Limits provides adequate corrosion j protection to ensure lthe structural' integrity of the Reactor Coolant System j

.over the life of the plant. The associated effects of exceeding the oxygen,

) chloride and. fluoride limits are time and temperature dependent. Corrosion

" studies.show that operation may be. continued with contaminant concentration j levels in excess of the Steady State Limits, up to the Transient Limits, for the~specified limited time intervals without having a significant effect on the structural l integrity of tdte Reactor Coolant System. The time interval permitting continued operation within the restrictions of the Transient Limits provides time'for taking. corrective actions to restore the contaminant ccncentrations'to within the Steady State Limits.

)

l I

i 4, ,

~

October 11, 1995 SEQUOYAH.-' UNIT'l B 3/4 4-4c Amendment No. 36, 109, 214

-l *t.

Q REACTOR COOL?ig, SYSTEM SURVEILLANCE REQUIREMENTS (Continued)

1. All nonplugged tubes that previously had detectable wall pene-trations (greater than 20%).
2. Tubes in those areas where experience has indicated potential problems.
3. A tube inspection (pursuant to Specification 4.4.5.4.a.8) shall be p3rformed on each selected tube. If any selected tube does not permit the passage of the cddy current prebe for a tube inspection, this shall be recorded and an adjacent tube shall be selectad and subjected to a tube inspection.
4. Indications left in service as a result of application of the tube support plate voltage-based repair criteria shall be R213 inspected by bobbin coil probe during all future refueling outages.
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 y partial tube inspection provided:
1. Tne tubes selected for these samples include the tubes from those areas'of the tube sheet array where tubes with imperfections were previously found.
2. The inspections include those portions of the tubes where imperfections were previously found.

Note: Tube degradation identified in the portion of the tube that R181 is not a reactor coolant pressure boundary (tube end up to the start of the tube-to-tubesheet weld) is excluded from the Result and Action Required in Table 4.4-2.

d. Implementation of the ateam generator tube / tube support plate repair criteria requires a 100 percent bobbin coil inspection for hot-leg and cold-leg tube support plate intercections down to the lowest R213 cold-leg tube support plate with known outside diameter stress corronion cracking (ODSCC) indications. The determination of the lowest cold-leg tube support plate intersections having ODSCC indications shall be based on the performance of at least a 20 percent random sampling of tubes inspected over their full length,
e. Inspection of dented tube support plate intersections will be performed in accordance with WCAP 15128, Revision 1, dated August 1999.

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

.following three categories:

Cateaory IneDection Results C-1 Less than 5% of the total tubes inspected are dearaded tubes and none of the inspected tubes are defective.

R213 SEQUOYAH - Unit 2 3/4 4-11 Amendment No. 181, 211, 213, i

R

,e *t REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENIa (Co;.tinued) h 4.4.5.4 Accentance Criteria

a. As used in this Specification:

1

1. Inngrfection means an exception to the dimensions, finish or contour of a tube from that required by fabrication drawings or specifications. Eddy-current tecting indications below 20% of the nominal tube wall thicknens, if detectable, may be con-sidered as imperfections.
2. Degradation means a service-induced cracking, wastage, wear or generel 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 vall thickness caused by degradation.
4. %_Deoradattra means the percentage of the tube wall thickness affected or removed by degradation.
5. Defect means an imperfection of euch severity that it exceeds the pluggins limit. A tube containing a defect is defective.

I 6. Pluomino Limit means the imperfection depth at or beyond which the tube shall be removed from service and is equal to 40% of the nominal tube wall thickness. Plugging limit does not .'pply to that portion of the tube that ic not within the pressure R181 boundary of the reactor coolant system (tube end up to the start of the tube-to-tubesheet weld) . This definition does not apply to tube support plate intersections if the voltage-based repair R213 criteria are being applied. Refer to 4.4.5.4.a.10 for the repair limit applicable to these intersections. This definition does not apply for greater than or equal to 40 percent deep i indications of axial PWSCC located within the tube support j plate, PWSCC indications located within and extending outside 1 the tube support plate, or PWSCC indications located at the edge of the tube support plate. Refer to 4.4.5.4.a.11 for the repair limits applicable to these intersections.

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 Earthquake, a loss-of-coolant accident, or a ateam line or feedwater line break as specified in 4.4.5.3.c, above.
8. Tube Inspection means an inspection of the steam generator tube from the point of entry (hot leg side) completely around the i U-bend to the top support of the cold leg. l
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 prior to initial POWER OPERATICN ud ng the equipment and techniques ea:pected t n be used during c"bsequent inservice inspections.

SEQUOYAH - UNIT 2 3/4 4-13 Amendment No. 181, 211, 213,

L:

.- , ; 5.

REACTOR COOLANT SYST2]

' _ SURVEILLANCE REQUIREMENTS - (Continued)w,

'10. . Tube Sucoort Plate PlgIning Lt311 is used for the disposition of

.an alloy.600. steam gencrator tube for continued service that is experiencing predominately axially oriented outside diameter stresc corrosion cracking confined within the thickness of the tube support plates. At tube support plate; intersections, the plugging (repair) ' limit is based on maintaining steam generator

); tube: serviceability as described below:

a. . Steam generator tubes, whose degradation is attributed-to outside diameter stress corrosion cracking within the bounds.of the tube' support plate with bobbin voltages less than or equal to the lower voltage repair limit (Note 1),

will be allowed.to remain in service.

b. Steam generator tubes, whose degradation is attributed to outside diameter stress corrosion cracking within the bounds of the tube support plate with a bobbin voltage greater than the lower voltage repair limit (Note 1), will R213 be repaired or plugged, except as noted in 4.4.5.4.a.10.c below,
c. Steam generator tubes, with indications of potential

' degradation attributed to outside diameter stress cotronion-cracking within the bounds of the tube support plate with a bobbin voltage greater than the lower voltage repair limit (Note 1), but less than or equal to upper voltage repair limit (Note 2), may remain in service if a rotating pancake coil inspection does not detect

. degradation. Steam generator tubes, with indications of outside diataeter stress corrosion-cracking degradation with a bobbin coil voltage greater than the upper voltage repair limit (Note 2) will be plugged or repaired,

d. Not applicable to SQN.
e. If an unscheduled mid-cycle inspectjen is performed, the following mid-cycle repair limits apply instead of the liPits identified in 4.4.5.4.a.10.a, 4.4.5.4.a.10.b, and 4.4.5.4.a.10.c.

The mid-cycle repair limits are determined from the following equations:

Yst y ,

E}

1. 0 + NDE + Gr (

U Va=Vm - (Va~Vm) SU l

April 9, 1997 4

SEQUOYAH'- UNIT 2 3/4 4-14 Amendment No. 28, 211, 213

>> i

l l \

,o 't j REACTOR COOLANT SYSTEM i j

SURVEILLANCE REQt.riREMENTS (Continued) )

, _ _ ,.,. 1 where j i

V URL = upper voltage repair limit Vutt = lower voltage repair limit VMURL = 'mid-Cycle upper Voltage repair limit based on time into cycle i

Vutat = mid-cycle lower voltage repair limit based on vmmt and 1 time into cycle At =

length of time since last scheduled inspection during R213 which Vunt and Vat were implemented CL = cycle length (the time between two scheduled steam generator inspections)

V3t = structural limit voltage Gr - average growth rate per cycle length j l

NDE = 95-percent cumulative probability allowance for j nondestructive examination uncertainty (i.e., a value l of 20-percent has been approved by NRC) j f

Implementation of these mid-cycle repair limits should follow the same approach I as in TS 4.4.5.4.a.10.a, 4.4.5.4.a.10.b, and 4.4.5.4.a.10.c.

Note 1: The lower voltage repair limit is 1.0 volt for 3/4-inch diameter l tubing or 2.0 volts for 7/8-inch diameter tubing. i Note 2: The upper voltage repair limit is calculated according to the methodology in GL 90-05 as supplemented. Vunt may differ at the TSPs I and flow distribution baffle. j l

11. Primary Water Stress Corrosion Craskina (PWSCC) Tube Suppotg Plate Pluccing Limit is used for the disposition of an Alloy 600 steam generator tube for continued service tnat is experiencing predominantly axially oriented PWSCC at dented tube support plate intersections as described in WCAP 15128, Revision 1, dated August 1999,
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 s.4-2.

l SEOUOYAH - UNIT 2 3/4 4-14a Amendment No. 28, 211, 213,

1

)~'l-REACTOR COOLANT SYSTQ.

SURVEILLANCE RSQUIREMENTS (Continued)-

D4.4.5.5 Esporta

a. Following each inservice inspection of steam generator tubes, the
number of tubes plugged in each steam generator shall be reported to 1 the commission within 15 days.
b. The complete results of the steam generator tube inservice inspection j shall be submitted.to the Commission in a Special Report pursuant to i specification 6.9.2 within 12 months following the completion of the  !

inspection. This Special Report shall include:  :

l

1. Number and extent of tubes inspected. l
2. Location'and percent of wall-thickness penetration for each indication of an imperfection.
3. Identification of tubes plugged. q
c. Results of steam generator tube inspections which fall into Category s 3 I C-3 shall be reported pursuant to Specification 6.6.1 prior to resumption of plant operation. .The written followup of this report l I

shall provide a description of investigations conducted to determine I cause of the tube degradation and corrective measures taken to '

prevent recurrence,

d. For implementation of the voltage-based repair criteria to tube support plate intersections, notify the staff prior to returning the steam generators to service should any of the following conditions arise
1. If estimated leakage based on the projected end-of-cycle (or if not practical using the actual measured end-of-cycle) voltage distribution exceeds the leak limit (determined from the licensing basis dose calculation for the postulated main steam R213 line break) for the next operating cycle.
2. 'If ciretmferential crack-like indications are detected at the tube support plate intersections.
3. If indications are identified that extend beyond the confines of the tube support plate.
4. If indications are identified at the tube support plate elevations that are attributable to primary water stress corrosion cracking.
5. If the calculated conditional burst probability based on the projected end-of-cycle (or if not practical, using the actual measured end-of-cycle) voltage distribution exceeds 1 X 10 4, notify the NRC and provide an assessment of the safety significance of the occurrence.

I R213 I

April 9, 1997 SEQUOYAH - UNIT 2 3/4 4-14b Amendment No. 28, 211, 213

) *b:

REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continued)-

_=

l L>

(- e. For implementation of the depth-based repair criteria for axial PWSCC at dented TSPs, the results of the condition monitoring and

- operational assessments will be reported to the NRC within 120 days

'following completion of the inspection. The report will include i

tabulations of indications found in the inspection, tabulations of L . tubes. repaired and left in service under the ARC, and growth rate

! distributions for indications found in the inspection as-well as the growth distributions used to establish the tube repair limits. Any

. corrective actions found necessary in the event that condition

! monitoring requirements are not met will be identified in the report.

'SEQUOYAH - UNIT 2 3/4 4 14c Amendment No.

y ej REACTOR COOLANT SYSTEM

' BASES where von represents the allowance for flaw growth between inspections and Vux represents the allowance for potential sources of error in the measurement of the bobbin coil voltage. Further discussion of the assumptions necessary to determine the voltage repair limit are discussed in GL 95-05.

The mid-cycle equation of SR 4.4.5.4.a.10.e should only be used during unplanned inspection in which eddy current data is acquired for indications at 4

R213 (

the tube support plates. '

SR 4.4.5.5 implements several reporting requirements recommended by GL 95-05 for situations which NRC wants to be notified prior to returning the l S/Gs to service. For SR 4.4.5.5.d., Items 3 and 4, indications are applicable ]

only where alternate plugging criteria is being applied. For the purposes of

.this reporting requirement, leakage and conditional burst probability can be calculated based on the as-found voltage distribution rather than the projected end-of-cycle voltage distribution (refer to GL 95-05 for more information) when it'is not~ practical tol complete these calculations using the projected EOC voltage distributions prior to returning the S/Gs to servica. Note that if leakage and conditional burst probability were calculated u ing the measured EOC voltage distribution for the purposes of addressing GL Sections 6.a.1 and 6.a.3 reporting criteria. then the results of the projected EOC voltage distribution should be provided per GL Section 6.b(c) criteria.

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 exceeding the repair P213 limit defined in Surveillance Requirement 4.4.5.4.a. The portion of the tube that the plugging-limit does not apply to is the portion of the tube that is not within the RCS pressure boundary (tube end up to the start of the tube-to- R181 tubesheet wald) . The tube end to tube-to-tubesheet weld portion of the tube does not affect' structural integrity of the steam generator tubes and therefore indications found in this portion of the tube will be excluded from the Result and Action Required for tube inspections. It is expected that any indications that extend from this region will be detected during the scheduled tube inspections. 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.

Tubes experiencing outside diameter stress corrosion cracking within the thickness of the tube support plate are plugged or repaired by the criteria of R213 4.4.5.4.a.10.

The steam generator tube repair limits for primary water stress corrosion cracking l (PWSCC) of SR 4.4.5 represents a steam generator tube alternate repair I criteria for greater than or equal to 40 percent deep PWSCC indications within the tube support plate, PWSCC indications within and extending outside the tube  !

support plate, or PWSCC indications located at the edge of the tube support j plate. The repair bases for PWSCC are not applicable to other types of i localized tube wall-degradation located at the tube-to-tube support plate I intersections. ,

The ARC includes completion of a condition monitoring assessment to h determine the end-of-cycle (EOC) condition of the tube bundle. Next, an ]

operational assessment is. completed to determine the need for tube repair on a )

forward-fit basis. The ARC is based on the use of crack depth profiles 1 obtained from Plus Point analyses. Burst pressures are calculated from depth profiles by searching the total crack length for the partial length that SEQUOYAH - UNIT 2 B 3/4 4-3a Amendment No. 181, 211, 213, l

l

I y by REACTOR COOLANT SYSTEM i

BASES 1 I

l I

results in the lowest burst pressure. The repair bases for PWSCC at dented TSP intersections is obtained by projecting the crack profile to the end of the next operating cycle and determining if the projected profile meets the burst margin requirements of WCAP 15128, Revision 1, dated August 1999. The following provides the limits and bases for repair established in the WCAP l analyses l 1

Maximum Depth Repair Limit j l

The repair limit for maximum depth is established to obtain a low I likelihood of SLB leakage for the operational assessment. The limit is based )

on ensuring against through-wall degradation at 95 percent confidence. The repair limit for maximum depth is obtained by reducing through-wall penetration by 2 percent for breakthrough, by NDE uncertainties on maximum depth at 95 percent confidence and by growth of maximum depth at 95 percent cumulative probability.

Note: The maximum depth repair limit is dependent upon growth rate and cycle length. Repair limits are updated when new growth data are obtained and when cycle lengths and/or operating temperatures are changed. f Crack Length Limits The crack length limit is defined as 0.60 inch from the centerline of the TSP.

Note: The 0.60 inch length limit allows a crack to begin the cycle with a length of 0.225 inch outside the TSP (TSP is 0.375 inch + 0.225 inch = 0.60 inch). The 0.225 inch allows a margin of 0.275 inch for potential growth to 0.5 inch outside the TSP which bounds expected growth at 95 percent confidence.

This maximum length limit is provided to limit potential freespan lengths and provide significant margins against leakage and burst. The crack left in

+

service must also satisfy the follewing operational assessment repair bases.

Operational Assessment Repair Bases If the indication satisfies the above maximum depth and total length requirements, the repair bases is then obtained by projecting che crack profile to the end of the next operating cycle and determining the burst pressure for the projected profile. The burst pressure is compared to the burst margin requirements in WCAP 15128, Revision 1, dated August 1999. Separate burst analyses are required for the total crack length and the length outside the TSP due to differences in burst margin requirements. If the projected EOC burst margin requirements are satisfied, the tube will be left in service.

The results of the .ondition monitoring and operational assessments will be reported to the NRC within 120 days following completion of the inspection.

Whenever the results of any steam generator tubing inservice inspection fall into Category C-3,-these results will be promptly reported to the Commission pursuant to Specification 6.6.1 prior to resumption of plant operation. Such cases will be considered by the Commission on a case-by-case basis.and may result in a requirement for analysis, laboratory examinations, tests, additional eddy-current inspection, and revision of the Technical Specifications, if necessary.

R213 SEQUOYAH - UNIT 2 B 3/4 4-3b Amendment No. 213, r

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