ML20248B156
| ML20248B156 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 09/19/1989 |
| From: | SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | |
| Shared Package | |
| ML20248B149 | List: |
| References | |
| NUDOCS 8910030114 | |
| Download: ML20248B156 (9) | |
Text
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REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS (Continusd) 4.4.5./
Accootence Criteria t.
As used in this Specification:
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1.
Imperfection means an excaption to the dieensions, finish or contour of a tube free that required by fabrication drawings or specifications.
Ed@-current testing indications below 20% of the nominal tube wall thickness, if detectable, may be considered as imperfections.
2.
Dooradntion means a service-induced cracking, wastage, wear or geners' corresten occurring on either inside or outside of a tube.
3.
Deoraded Tube means a tube containing imperfections greater than or equal to 25 of the nominal wall thickness caused by degradation.
4.
% Degradation osans the percentage of the tube well thickness affactee or removed by degradation.
5.
Defect means an imperfection of such severity that it exceeds the pluggin defective. g er repair limit. A tube containing a defect is 6.Yhuntins or Roosir Limit means the taperfection depth at er bey whic 5 tse tune shall se repaired (i.e. sleeving) er removed from service by thickness. plugging and is 1 to 405 of the nominal tube wall This definition not apply to the area of the tubesheet reglen below the F* distance provided the tube is not degraded (i.e., no indications of cracking) within the F*
distance.
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4 s.
For the area in the upper weld joint, ary degradet. ion shall be plugged unless it can be clearly demonstrated by s'quali-fled NDE technique that the degradation is less than 405 of the nesinal well thickness of the sleeve for 10 imperfec-tions er less than 45 nominal wall thickness of the tube I
for 0.D. imperfections.
b.
For the area of the tube behind the sleeve and above the perweldjoint,tubeswith degradation shall be ogged unless it can be clearl demonstrated by a qualified E technique, that the degra fen is less than 405 of the nominal well thickness, For the area below the upper weld i
c.
than 405 of the nominal sleeve wa) point, Aqr defect greater thickness shall be pb.gged.
1 SU MER - UNIT 1
- 4 4-14 Amendment No. IW' 59 W98aM 8?8%
p PNV
REACTOR COOLANT SYSTEN SURVEILLANCEREQUIREMENT5(shstinued) l F f.
Unserviceabledescribestheconditionofatubeifitleaksor contains a defect large eno to affect its structural integrity in the event of an rating Basis Earthquake, a loss-of-coolant accident ot a staas line or feechtater line break es specified in 4. W. 3.c above.
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Tube ' nspeco, ion means an inspection of the steam generator tube from ';he po' nt of ent;'y (hot leg side) completely around the U-bend to the top support of the cold leg.
log.
Sleeve Insmetion means an inspection of the sleeved portion of I
<;he tube.
'nis inspection will include 3 inches of the parent tube directly above the upper weld, the upper weld which foms the new pressure boundary, and the sleeve amaterist below th,e upper weld.
11 J6.
Repaired tube means a tube that has undergone a process that re ttbe O S ce nw< c., of h Rht7 wi estaje11snes lts: serviceability.m w e e -tu b.:
uw % sw a w um The Combustion E neering Inc. weld sleeve process will be used Mr report C -337-P.
Tk. EbeccK + wac.ex KintYa t s\\teve. pfteess i n b e ow.d pec repr+
6Aw-aoys P.
i St#9tER - UNIT 1 3/4 4-14a Amendment No. 59
$ SURVEILLANCE REQUIREMENTS (Continued)
J2., f.
Preservice Insoection means an insp' ction of the full length of l
e each tube in each steaa ponerator perfomed by addy current techniques prior to serv < ce to establish a baseline condition of the tubing. This inspection shall be perfomed after the field hydrostatic test and prior to initial POWER OPERATION using the equipment and techniques expected to be used during subsequent inservice inspections.
13, )d.
F* Distance is the distance into the tubesheet from the face.
l of the tunesheet or the top of the last hardroll, whichever is lower (further into the tu>esheet) that has been conservatively" chosen to be 1.5 inches.
Pi. Jf.
F* TUBE is the tube with degradation equal to or greater than l
A m, below the F8 distance and not degraded (i.e., no indica-tions of cracking) within the F8 distance. The application of F* expires at the end of the fifth fuel cycle, b.
The steam generator shall be determined OPERABLE after completing plugging limit) g actions (plug or repair all tubes exceeding the the corresponding required by Table 4.4-2.
4.4.5.5 Reports a.
Within 15 days following the completion of each inservice inspection of steam generator tubes the number of tubes plugged or repaired in eachsteamgeneratorshallbereportedtotheCommissioninaSpecial Report pursuant to Specification 8.9.2.
b.
The complete results of the steam generator tube inservice inspection
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shall be submitted to the Consission in a Special Leport pursuant to Specification 6.9.2 within 12 conths following the completion of the inspection.
This Special Report shall includes 1.
Number and extent of tubes inspected.
2.
Location and percent of well-thickness penetration for each indication of an imperfection.
3.
Identification of tubes plugged er repaired.
c.-
Results of staas generator tube inspections which fall into Category C-3 and require prompt notification of the Commission shall orter to reseption of te reported pursuant to 10 CFR 50.7t(b)2(1)FR to.73(a)2(ii) shall be plant operation.
A reportdpursuant to 10 C submitted to provide a description of investigattens conducted to determine cause of the tube (egradstion and corrective' measures taken to prevent recurrence.
e d.
The results of inspections of F8 tubes shall be repdFsed to the ONRR, prior to the restart Commission in a report to the Director,This report shall include:
of the unit following the inspection.
1.
Identification of F8 tubes, and 2.
Location and size of the degradation NRC approval of this report is not required prior to restart.
$UpgiER - UNIT 1 3/4 4-15 Amendment No. 35, M, 59
ATTACHMENT 2 i
l Safety Analysis and Technical Justification l
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' to Document Control Desh Letter September. 19.-1989 Page 1 of 2 Description of Chance The requested Technical Specification change will allow the use of B&W sleeves for steam generator tube repair. The change requires referencing B&W topical report BAW-2045P, " Recirculating Steam Generator Kinetic Sleeve Qualification for 3/4 Inch 0.D. Tubes," in Technical Specification Section 4.4.5.4.10.
The topical was submitted to the NRC by a letter dated June 9, 1988, frcm Mr. James H. Taylor of B&W to Mr. L. C. Shao of the NRC. A supplement to the origindl B&W submittal was made on December 12, 1988 which contained answers to NRC questions and transmitted a non-proprietary version of the topical. The currently allowed Combustion Engineering weld sleeve process will be retained in the Technical Specifications as an option. Also, an editorial numbering / title revision is being made to Section 4.4.5.4.6 to i
more clearly delineate tube versus sleeve plugging or repair limits.
Technical Justification and Safety Analysis B&W topical BAW-2045P contains the results of the sleeve design verification which included analysis and confirmatory testing.to demonstrate the acceptability of the steam generator sleeving technique for defective tubes.
The design and operating conditions specified for the sleeve bound the VCSNS steam generator design conditions.
In general, the generic topical (BAW-
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2045P) was written utilizing VCSNS specific design data.
l The sleeve design described in BAW-2045P is qualified for two lengths, eleven inches and seventeen and one half inches. The lower end of each sleeve is located approximately 16 inches from the primary face of the tubesheet. The I
shorter sleeve may_be utilized in all the steam generator tubes (including the peripheral tubes which typically do not permit the introduction of sleeves due to the close proximity of the bowl in that area). The longer sleeve extends further into the tube past the flow distribution baffle.
I The sleeve material is thermally treated Alloy 690 Inconel with a specified minimum wall thickness of 0.039 inches. (The required minimum thickness is 0.027 inches based on primary side design pressure). This material has been demonstrated to be much more resistant to corrosion phenomenon as detailed in BAW-2045P. Design and operating conditions listed in Table 4.2.1 of BAW-2045P bound those for VCSNS. The upper sleeve / tube joint is produced by a kinetic weld / expansion which is subsequently stress relieved. The joint is.
I qualified as both a strength and seal weld. The lower joint may consist of either a kinetic weld in the tubesheet or a mechanically sealed joint produced by rolling the sleeve in the tubesheet. The lower joint is qualified for applicable loads without taking credit for the original strength of the tube rolled into the tubesheet.
.The adequacy of the sleeve to withstand cyclic loadings was demonstrated using fatigue testing. Fatigue testing consisted of cyclic vibration, pressure, thermal, and axial loading. These. tests were performed to demonstrate the structural adequacy of the installed sleeve. In all cases, I
the results of the tests indicated that the sleeve conformed to the design requirements of the steam generators.
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' to Document Control Desk letter September 19, 1989 Page 2 of 2 Based on Regulatory Guide 1.121 guidelines for tube degradation limits, a plugging limit of 40% of the original sleeve wall has been established. Eddy current techniques are available to perform necessary sleeve / tube inspections for defect detection and to verify proper installation of the sleeve. The available techniques are capable of providing 20% defect sensitivity in the required areas of the tube / sleeve pressure boundary. The inspection I
requirements currently contained in the Technical Specifications do not j
require any changes, j
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A ATTACHMENT 3 No Significant Hazards Determination
' to Document Control Desk Letter September 19, 1989 Page 1 of 2 NO SIGNIFICANT P,dAkDS DETERMINATION Description of amendment request:
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The proposed change revises the surveillance requirements of Technical Specification 3/4.4.5 to allow the use of the Babcock & Wi?cox (B&W) kinetic sleeving process for steam generator tube repair. Also, an editorial numbering / title revision is being made to more clearly delineate tube versus sleeve plugging or re; air limits. The Technical Specification currently J
allows the use of the Combustion Engineering (CE) weld sleeve process.
However the B&W sleevt because of its shorter length, may be used in more-locations in the steam 'enerator than the CE sleeve. The proposed change will provide South Carclina Electric & Gas Company with another alternative for handling degraded t?bes.
Basis for no significant hazards determination:
Pursuant to 10CFR50.91, the following analyses provide a determination that the proposed change poses no significant hazard as defined by 10CFR50.92.
1)
The proposed change does not involve a significant increase in the f
probability or consequer.ces of an accident previously evaluated.
l As discussed in topical report BAW-2045P, the steam generator sleeve has
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been analyzed and tested to the operating and design conditions of the
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original tube. The probability or consequences of a previously evaluated accident is not increased since the structural integrity of the steam generator tube is maintained by the sleeving process.
In addition, the sleeve is less susceptible to the identified stress corrossion failure mechanisms of the original tube because of the use of an improved material, Alloy 690 Inconel, and the B&W specified 1
installation process. The continued integrity of the sleeve will be verified by the Technical Specification inspection requirements. The numbering / title revision is purely editorial in nature and has no technical impact.
2)
The proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.
The purpose of the sleeve is to repair a degraded steam generator tube in order to maintain the function and integrity of the tube. The sleeve l
functions in essentially the same manner as the original tube.
J Repairing the tube to a serviceable condition utilizing this sleeving process does not create the possibility of a new or different kind of accident.
3)
The proposed change does not involve a significant reduction in a margin of safety.
Attachn.ent 3 to Document Control Desk Letter September 19, 1989 Page 2 of 2 The potential for primary to secondary leakage is reduced by the addition of a steam generator tube sleeve. Also, the structural integrity of the tube is maintained by the sleeve and sleeve / tube weld.
The proposed sleeving technique provides an increased margin of safety over plugging the tube and removing it from service. The effect of sleeve installation on steam generator performance was analyzed for heat transfer, flow restriction and steam generation capacity. The results show that plugging one tube is equivalent to the heat transfer reduction of sleeving 48 tubes, the primary flow reduction of sleeving 20 tubes, and loss of steam generation capacity of sleeving 40 tubes. Therefore, sleeving provides additional margin when compared to the plugging alternative.
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