ML20216D114
| ML20216D114 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 09/02/1997 |
| From: | NORTHERN STATES POWER CO. |
| To: | |
| Shared Package | |
| ML20216D101 | List: |
| References | |
| NUDOCS 9709090218 | |
| Download: ML20216D114 (12) | |
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ATTACHMENT 2 Proposed Changes Marked Up on Existing Technical Specification Pages
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- ER'%88!*85888882 P PDR
TS.4.12-1 REV 30 S/25/?S 4.12 STEAM CENERATOR TUBE SURVEILIANCE Apolicability Applies to inservice surveillance of the steam generator tubes.
Obiective To assure the continued integrity of the steam generator tubes that are a part of the primary coolant pressure boundary.
Specification Steam generator tubes in each unit shall be determined operable by the following:
1 A. Steam Generator Sample Selection and Inspection Each steam ;enerator st.all be determined operable in accordance with the in-service inspection schedule in Specification 4.12.C. The in service inspection may be limited to one steam generator on a rotating schedule encompassing 6% of the tubes in the single steam generator, provided the pr-vious inspections indicated that the two steam generators are performing in a like manner.
B. Steam Generator Tube Sample Selection and Insnection The steam generator tube minimum sample size, inspection result
) classification, and the corresponding action required shall be a-
) specified in Tables TS.4.12-1[an{}TS14}12y2. The in servico inspection of steam generator tubes shell be performed ar the frequencies specified in Specification 4.12.C and the inspected tubes shall be verified acceptable per the acceptance criteiin of Specification 4.12.D. The tubes selected for each in-service inspection shall include at least 3% of the total number of tubes in
'all steam generators %5Fatmastt20%?of5thent6ts1ThUmberTof31'ebVss igeM$pQiMth'skekn(;lgengators:~ the'51sAs ~se1$cted"f$li"$he'se ~
inspections shall be selected on a random basis except:
- 1. Where experience in <imilar plants with similar water chemistry indicates critical areas to be inspected, then at least 50% of the tubes inspected shall be from these critical areas.
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TS.4.12-2 REV -119 5/15/94
- 2. The first sample of tubes selected for each in service inspection (subsequent to the preservice inspection) of each steam generator shall include:
(a) All tubes that previously had detectable wall penetrations
(>20%) that have not been plugged or sleeve repaired in the affected area.
(b) Tubes in those areas where experienced has indicated potential problems.
(c) A tube inspection (pursuant to Specification 4.12.D,1.(h))
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.
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- 3. In addition to the sample required in Specification 4.12.B.2.a through c, all tubes which have had the F* criteria applied will be instected in the F* regions of the roll expanded region. The roll expanded region of these tubes may be excluded from the requirements of 4.12.B.2.a.
- 4. The tubes selected as the second and third samples (if required by Tableis TS.4.12 1[6M TS]411232) during each inservice inspection may be subjected to a partial tube [oyfs1hsvg inspection provided:
(a) The tubes selected for these samples include the tubes from those areas of the tube sheet array where tubes with imperfections were previously found.
(b) The inspections include those portions of the tubes [or sleeves where imperfecticns were previously found.
The results of each sample inspection shall be classified into one of the following three categories:
Category Inspection Renults C-1 Less than 5% of the total tubes inspected are degraded tubes and none of the inspected tubes are defective.
C-2 One oc more ubes, but not more than 1% of the total tuben ins;. acted are defective, or between 5% and 10%
of the tot <! 2bes inspected are degraded tubea.
C-3 More than 10% of the total tubes inspected are degraded tubes or more that 1% of the inspected tubes are defective.
Note: In all inspections, previously degraded tubes must exhibit significant (>10%) further wall penetrations to be included in the above percentage calculations.
TS.4.12 5 REV 11* S/15/95
- 2. The steam generator shall be determined OPERABLI after completing the corresponding actions (plug or repair by sleeving all tubes exceeding the repair limit and all tubes containing through wall s cracks or classify as F* tubes) required by Tables TS.4.12-1[and TSI$312i2-E. Reports
- 1. Following each in-service inspection of steam generator tubes, if there are any tubes requiring plugging or sleeving, the number of tubes plugged or sleeved in each steam generator shall be reported to the Commission within 15 days.
- 2. The results of steam generator tube inservice inspections shall be included with the summary reports of ASME Code Section XI inspections submitted within 90 days of the end of each refueling outage. Results of steam generator tube inservice inspections not associated with a refueling outage shall be submitted within 90 days of the completion of the inspection. These reports shall include:
(1) number and extent of tubes inspected, (2) location and percent of wall-thickness penetration for each indication of an imperfection and (3) identification of tubes plugged or sleeved.
- 3. Results of steam generator tube inspections which fall into Category C-3 require notification to the Commission prior to resumption of plant oporation, and reporting as a special report to the Commission within 30 days. This special report shall provide a description of investigations conducted to determine cause of the tube degradation and corrective measures taken to prevent recurrence.
- 4. The results of inspections performed under Specification 4.12,B for all tubes that have defects below the F* distance, and were not plugged, shall be reported to the Commission within 15 days following the inspection. -The raport shall include:
- a. Identification of F* tubes, and
- b. Location and extent of degradation.
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- B.4.12 1 REV 91 10/27/S9 4.12 STEAM GENERATOR TUBE SURVEILIANCE Bases The Surveillance Requirements for inspectior. of the steam generator tudes 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, Revisica 1. In-service inspection of steam generator tubing is essen-tial in order to maintain surveillance of the conditions of the tubes in the event that there is evidence of archanical damage or progressive degradation due to design, manufacturing errors, or in-service condi-tions that lead to corrosion. In-service 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 At"theTrequest?ofEths1NRC[a7;requiremeht?forTin;sefvihelinspshioR~"of"at least 20% of:!the totalHnumber of::aleevestiniservice?in bothLateam generators wasjadded to TSL4212.BVilnladdition/ Table!TS 4 12.E2 Was
' addedctoprovide}sampleLexpansion!requirementsiba4d1onthe'resulpsiof thelinitialisampletinspectionisimilarlto(Table (4;12 li;This(typelof kampleEsize"andiexpansion!re'qtitrementiis "consisteritinithi helEPRIs t PWR Steam: Generator-Examination { Guidelines (TheTsample:selectionits[ applied to teach l type (o f ? sleeve b T:t ypes L of; sleeves tare (categorizedf byisuch characteristicsfas {thMinstallationivendor[thetsleeve' materialk:th' ?e type of! joint'auch fas lowerJedgefweld(or lowerchardirolld intsh: the(sleeve locationisuchfasjtube support; place or tu.besheetfand;whetherEnotethe~
welded ljointslhavefreceivedipostjweld;heatstreatment.
The plant is expected to be operated in a manner such that the secon-dary coolant will be maintained within those parameters found to result in negligible corrosion of the steam generator tubes. If the secondary coolant chemistry is not maintained within these parameters, localized corrosion would most likely result in stress cerrosion cracking.
The extent of cracking during plant operation would be limited by the limitation of steam generator leakage between the primary coolant system and the secondary coolant system (primary-to-secondary leakage -
1.0 gpm). Cracks having a primary-to-secondary leakage less than 1.0 gpm during operation will have an adequate margin of safety against failure due to loads imposed by design basis accidents (Reference 1). Operating plants have demonstrated that primary-to-secondary leakage as low as 0.1 gpm will be detected by radiation monitors of steam generator blowdown. Leakage in excess of 1,0 gpm will require plant shutd>wn and an unscheduled eddy currant inspection, during which the leaking tubes will be located and plugged or sleeved.
Wastage-type defects are unlikely with proper chemistry treatment of secondary coolant. However, even if this type of defect occurs it will be found during scheduled in service steam generator tube inspections.
Repair or plugging will be required of all tubes with imperfections that could develop defects having less than the minimum acceptable wall thickness prior to the next inservice inspection which, by the definition of Specification 4.12.D.l.(f), is 50% of the tube or sleeve nominal wall thickness. Wastage type defects having a wall thickness greater than 0.025 inches will have adequate margins of safety against failure due to loads imposed by normal plant operation and design basis accidents (Reference 1). Steam generator tube inspections of operating l
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Tabis!TS14:12-2 Steam 'Genersthr-;; Tube s Sleeve ~;Inspecrion isEsamp1CInspection 2nd' Sample ~ Inspection Actiori" Required
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Sasple* Size Rssults Action! Req 6 ired Result
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A? minimum::sf 20Co;f C1 Norie N/A N/A Tube Sleeves?(1)
Cj.2 Inspuc{al.lyrusain1Hftube C-1 None sleevesiin"this:S.G; and plug'or
' repair 'defectine rsleeved . tubes ; _
C-2 Plug;or" repair ^defdetive; sleeved. tubes C-3
~
Perform 'actiah
- forf'C;3 resultiof!first: sample C23 TrispectTa11JtsbsEsleeves71riSthis The"other None S.C.giinspect?20% Toff the tube S.G.:fis)C-1 sleevesfindthelother;S.Gs,yand Pl ug;or! repair 4dsfectivejsleeved tubes Perform 'actioti'for* C-2 ThE"sther S.G.;is1C-2 results of firse sample
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The ~other Inspect ^a117 tube (s1eeves";is S.G isLC-3 each S.G? and plug or g
repair; defective sleeved tubes g i;l) Each type- of isleeve 'is co.nsidered;a,seporate; pop,ulation;forJetermination .of scope; i expansion m
9mm8 N
0 N
Attachment 3 Revised Technical Specification Pages l
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-e TS,4,12 1 REV 4.12 STEAM GWRATOR TUBE SURVEILIANCE Aeolicability.
l Applies to inservice surveillance of the steam generator tubes.
Obiective l To assure the continued integrity of the steam generator tubes that are
{~ a-part of the. primary coolant pressure boundary, Specification l
L
. Steam generator tubes in each unit shall be determined operable by the following:
A. Steam Generator Sample Selection and Inspection Each steam generator shall be determined operable in accordance with the in service
- inspection schedule in Specification 4,12,C. The in-service inspection may be limited to one steam generator on a rotating schedule encompassing 6% of the tubes in the single steam generator, provided the previous inspections indicated that-the two steam generators are performing in a like manner, B, Steam Generator Tube Samole Selection and Inspection The steam generator-tube minimum sample size, inspection result classification, and the corresponding ~ action required shall be as specified-in Tables TS.4.12-1-and-TS 4.12-2 The in service l inspection of. steam generator tubes shall be performed at the frequencies specified in Specification 4,12,C and the inspected tubes shall be verified acceptable per the acceptance criteria of Specification 4,12,D, The tubes selected for each in-service inspection shall include at.least 3% of the total number of tubes in; all steam generators and at least 20% of the total number of sleeves in service in both steam generators; the tubes selected for these-
= inspections shall be selected on a random basis except:
- 1. Where experience in similar plants with similar water chemistry indicates critical areas to be ; inspected, then at least.50% of the tubes inspected shall be from these critical areas, A __
- TS.4.12 2 REV
- 2. The first sampla of tubes selected for each in service
' inspection (subsequent to the preservice inspection) of each steam generator shall include:
(a) All tubes that previously had detectable wall penetrations
(>20%) that have not been plugged or sleeve repaired in the affected area.
(b) Tubes in those areas where experienced has indicated potential problems.
(c) A tube inspection (pursuant to Specification 4.12.D.1.(h)) l 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 i
inspection,
- 3. In addition to the sample required in Specification 4.12.B.2.c through c, all tubes which have had the F* criteria applied will be inspected in the F* regions of the roll expanded region. The roll expanded region of these tubes may be excluded from the requirements of 4.12.B.2.a.
- 4. The tubes selected as the second and third samples (if required by Tables TS.4.12-1 or TS.4.12-2) during each inservice inspection may be subjected to a partial tube or sleeve inspection provided:
(a) The tubes selected for these samples include the tubes from those areas of the tube sheet array wheia tubes with imperfections were previously found.
(b) The inspections include those portions of the tubes or sleeves where imperfections were previously found.
The results of each sample inspection shall be classified into one of the following three categories:
Category Inspection Results C-1 Less than 5% of the total tubes inspected are degraded tubes and none of the inspected tubes are defective.
C-2 One or more tubes, but not more than 1% of the total tubes inspected are defective,.or between 5% and 10%
of the total tubes inspected are degraded tubes.
C-3 More than 10% of the total tubes inspected are degraded tubes or more that 1% of the inspected tubes are defective.
Note: In all inspections, previously degraded tubes must enhibit significant (>10%) further wall penetrations to be included in the above percentage calculations.
- TS.4.12 5 REV -
- 2. The steam generator shall be determined OPERABLE after completing the corresponding actions (plug or repair by sleeving all tubes exceeding the repair limit and all tubes containing through-wall cracks or classify as F* tubes) required by Tables TS.4.12 1 and TS.4.12-2.
E. Reports
- 1. Following each in service inspection of steam generator tubes, if there are any tubes requiring plugging or sleeving, the numbet of tubes plugged or sleeved in each steam generator shall be reported to the Commission within 15 days.
- 2. The results of steam generator tube inservice inspections shall be included with the summary reports of ASME Code Section XI inspections submitted within 90 days of the end of each refueling outage. Results of steam generator tube inservice inspections not associated with a rafueling cutage shall be submitted within 90 days of the completion of the inspection. These reports shall include:
(1) number and extent of tubeo inspected, (2) location and porcent of wall-thickness penetration for each indleation of an imperfectien and (3) identification of tubes plugged or sleeved.
- 3. Results of steam generator tube inspections which fall into Category C 3 require notification to the Commission prior to resumption of
_ plant operation, and r3 porting as a special report to the' Commission within 30 oays. This special report shall provide a description of investigations conducted to dotermine cause of the tube degradation and morrective measures taken to prevent recurrence.
4, The results of inspections performed under Specification 4.12.B for all tubes that have defects below the F* distance,-and were not plugged, shall be reported to the Commission within 15 days following the inspection. The report shall include:
- a. Identification of F* tubes, and
- b. Location and extent of degradation.
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B.4.12-1 REV
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4.12 SJffM GENERATOR TUB.ji..Sl.!EVEILLANCE
, J 7 . Bnnes 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 inse vice inspection of steam generator tubes is based on a modification of Regulatory Guide 1.83, Revision 1. In service inspection of steam generator tubing is essen-1 -_
- tial in order to maintain surveillance of the conditions of the tubes in the event that there is evidence cf mechanical damage or progressive
=- degradation due to design, manufacturing errors, or in-service condi-
?. tions that lead to corrosion. In-service inspection of steam generator tubing also provides a means of characterizing the nature and cause of i any tube degradation so that corrective measures can be taken.
{ At the request of the NRC, a requirement for in-service inspection of at least 20% of the total number of sleeves in service in both steam ,
E- generators was added to TS 4.12.B. In addition, Table TS 4.12. 2 was
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L added to provide sample expansion requirements based on the results of the initial sample inspection similar to Table 4.12-1 This type of g sample size and expansion requirement is consistent with the EPRI pWR I Steam Generator Examination Guidelines. The sample selection is applied tr., ecch type of sleeve. Types of sleeves are categorized by such i characteristics as the installation vendor, the sleeve material, the type k
of joint such as lower edge weld or lower hard roll joints, the sleeve location such as tube support plate or tubesheet and whether not the welded joints have received post weld heat treatment.
The plant is expected to be operated in a manner such that the secon-dary coolant will be maintained within those parameters found to result q- in negligible corrosion of the steam generator tubes. If the secondary coolant chemistry is not maintained within these parameters, localized g corrosion would most likely result in stress corrosion cracking.
The extent of cracking during plant operation would be limited by the E limitation of steam generater leakage between the primary coolant g systen and the secondary coolant system (primary-to-secondary leakage -
= 1.0 gpm). Cracks having a primary-to-secondary leakage less than 1.0 gpm g during operation will have an adequate margin of safety against failure due to loads imposed by design basis accidents (Reference 1). Operating
[ plants have demonstrated that pr; mary-to-secondary leakage as low as p 0.1 gpm will be detected by radiation monitors of steam generator i blowdown. Leakage in excess of 1.0 gpm will require plant shutdown and an unscheduled eddy current inspection, during which the leaking tubes E~
P will be located and plugged or sleeved.
Wastage-type defects are unlikely with proper chemistry treatment of g secondary coolant. However, even if this type of defect occurs it will be found during scheduled in-service steam generator tube inspections.
g Repair or plugging will be required of all tubes with imperfections E that could develop defects having less than the minimum acceptable wall thickness prior to the next inservice inspection which, b; the r
P definition of 3pecification 4.12.D.l.(f), is 50% of the tube or sleeve
[ . nominal wall thickross. Wastage type defects having a wall thickness greater than 0.023 inches will have adequate margins of safety against failure due to loads imposed by normal plant operation and design basis accidents (Reference 1). Steam generator tube inspections of operating
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Table TS.4.12-2 -
Steam Generator Tube Sleeve Inspection 1st Sample Inspection 2nd Sample Inspection Sampl Size Result Action Required Result Action Required f A minimum of 20% of C-1 None N/A N/A j Tube Sleeves (1)_
m C-2 Inspect all remaining tube C-1 None sleeves in this S.G. and plug or repair defective sleeved tubes.
C-2 Plug or repair defective l sleeved tubes C-3 Perform action for C-3 result of first sample C-3 Inspect all tube sleeves in this The other None S.G., inspect 20% of the tube S.G. is C-1 sleeves in the other S.C., and plug or repair defective sleeved ubes The other Perform action for C-2 S.G. is C-2 results of first sample-The other Inspect all tube sleeves in S.G is C-3 each S.C. and plug or repair defective sleeved tubes >
te (1) Each type of sleeve is considered a separate population for deteomination of scope expansion ['
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