ML20012D885
| ML20012D885 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/22/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20012D883 | List: |
| References | |
| NUDOCS 9003290046 | |
| Download: ML20012D885 (4) | |
Text
,
>~
je5"ag
,p;.
' f, UNITED STATES S
j NUCLEAR REGULATORY COMMISSION e
a t.
I WASHWGTON D. C. 20666 k.....
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGUALTION
_ SUPPORTING AMENDMENT NO. 91 TO FACILITY OPERATING LICENSE h0. NPF-12 SOUTH CAROLINA ELECTRIC & GAS COMPANY SOUTH CAROLINA PUBLIC SERVICE AUTHORITY VIRGIL C. SUPNER NUCLEAR STATION, UNIT NO.1 DOCKET NO. 50-395
1.0 INTRODUCTION
By letter dated September 19, 1989, South Carolina Electric & Gas Company (SCE&G) requested a revision to the Technical Specifications for the Virgil C. Sumner Nuclear Station.(VCSNS). The proposed change would revise the surveillance requirements of Technical Specification (TS) 3/4.4.5 Steam Generators, to permit the option of using the Babcock &
Wilcox(B&W)kineticsleevingprocessforsteamgeneratortuberepair.
This change will provide SCE&G with an alternative to plugging degraded tubes and will provide them with ar, additional sleeving source.
Clarifying information in support of the amendment request was submitted on December 11, 1989 and on January 16, 1990.
The January 16,'1990 submittal did not alter the proposed action or affect the initial determination noticed in the Federal Register on January 10, 1990.
2.0 EVALUATION Technical Specification 4.4.5.4.a.10, Acceptance Criteria-Repaired Tube, presently a~110ws steam generator tube repair using the Combustion Engineering sleeve process.
The requested TS change would: (1) retitle item a 6 under TS 4.4.5.4 to " Tube Plugging or Repair Limit"; (2) would take items a-c presently crder a.6 and place them under a new item a.7 entitled, " Sleeve Plugging or Repair Limit"; (3) renumber existing items a.7 through a.11 of TS 4.4.5.4.a as a result of the addition of the new a.7; and (4) modify the existing item a.10 to allow the use of B&W sleeves for steam generator tube repair.
The currently permitted Combustion Engineering sleeve process is retained in the TS 4.4.5.4.a.10 as an option.
The change to existing TS 4.4.5.4.a.10 to allow the use of the B&W sleeve references B&W. topical report BAW-2045P, " Recirculating Steam Generator Kinetic Sleeve Qualification for 3/4 Inch 0.D. Tubes." The topical report was submitted to the NRC by a letter dated June 9, 1988, and a supplement to the original submittal was made on December 12, 1988, which contained answers to the NRC request for additional information.
The staff approved the topical report as being suitable for referencing in a letter to James H. Taylor of B&W from James E. Richardson, dated January 4,1990.
- g;l32gggggggp P
a
+
l I
l 1 The purpose of a sleeve is to repair a degraded steam generator tube in f
order to maintain the fur.ction and integrity of the tube.
The sleeve functions in essentially the same manner as the original tube.
B&W topical report BAW-204EF describes, in detail, the analytical methods used for design and qualification of the D&W sleeve.
The topical report lists the specifications, mainly ASME Boiler and Pressure Vessel Code seguirenents, used in design, procurement and qualification of the sleeve.
It also sumnarizes tne transients used to establish sleeve t
- loading, BAW-2045p contains the results of the sleeve design verification which included analysis and confirnatory testing to demonstrate the acceptability of the steam generator sleeving technique for defective r
tubes.
The design and operating conditions specified for the sleeve bound the VCSNS steam generatur design conditions.
Acccrding to the SCE&G, the generic topical rt. port (BAW-2045P) was written utilizing VCSNS specific design data.
The sleeve design described in CAW-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 shorter sleeve nay be utilized in all the steam generator i
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.
The sleeve material is thernally treated Alloy 690 Inconel with a i
specified minimum wall thickness of 0.039 inches.
The required minimum thickness is 0.027 inches based on primary side design pressure.
This n.aterial has been demonstrated to be nuch more resistant to corrosion phenomenon as detailed in BM-2045P.
The design and operating conditions of BAW-2045P bound these for VCShS.
The upper sleeve / tube joint is produced by a kinetic weld / expansion which is subsequently stress relieved.
The joint is 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 l
tube sheet.
Therefore, the structural integrity of the tube-is maintain <td by the sleeving process.
The adequacy of the sleeve to withstand cyclic loadings was demonstrated using fatigue testing.
Fatigue testing consisted of cyclic vibration, pressure, thernal, and axial loading.
These tests were performed to demonstrate the structural adequacy of the installed sleeve.
In all cases, the results of the tests indicated that the sleeve conformed to the design requirenents of the steam generators.
i n
V-
~,-
.,, -,. -, +.,,
j 4
- j i
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.
SCE&G has stated that available techniques are capable of i
providing 20% defect sensitivity in the required areas of the tube / sleeve pressure boundary.
i A proprietary method is described in the topical report, with supporting validation data, that demonstrates the inspectability of the sleeve and underlying tube.
SCE&G has provided a commitment to validate the i
adequacy of any system that is used for periodic inservice inspections as well as a commitment to upgrade testing methods as better methods are developed and validated for commercial use.
l Based on the staff's previous review and approval of BAW-2045(P), as revised to include the changes described in the letter dated December 12, 1988, from J. H. Taylor, B&W, to L. C. Shao, NRC, the staff has concluded.
that the use of B&W sleeves is acceptable. Accordingly, the change to TS 4.4.5.4.a.10 to allow use of B&W sleeves for repair is acceptable.
The retitling of item a.6 under TS 4.4.5.4, the placement of items a-c, presently under a.6, under a new item a.7 and the renumbering of existing items a.7 through a.11 of TS 4.4.5.4.a as a result of the addition of the new a.7 are editorial in nature. The staff approves these changes also, i
3.0 ENVIRONMENTAL CONSIDERATION
1 This amendnent involves a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration, and there has been no-public consent on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 51.22(c)(9). Pursuantto10CFR51.22(b)noenvironmentalimpactstatement or environmental assessment need be prepared in connection with the issuance of this amendment.
i
4.0 CONCLUSION
1 The Commission has issued a " Notice of Consideration of Issuance of Anendnent to Facility Operating License and Propose No Significant Hazards Consideration Determination and Opportunity for Hearing" which was published in the FEDERAL REGISTER on January 10, 1990 (55 FR 948) and consulted with the State of South Carolina.
No public comments or request for hearing were received, and the State of South Carolina did not have comments.
~
c.*
4 The staff has concluded, based upon the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the p(ublic will not be endangered by oper& tion in the preposed manner, and regulations and tie issuance of this amendment will not be inimic41 to the comnon defense and security or to the health and safety of the publi c.
The additional infornetion provided by the~ licensee on January 16, 1900 clarified certain matters in response to a questien raised by the staff.
4 The' correspondence did not change the substance of the amendement reques t.
Principal Contributors:
- 11. Con ra d E
J. f4yes Dated: March 22, 1990 Y
F h-i 1-l l-
-