ML20080F404
| ML20080F404 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 01/06/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20080F400 | List: |
| References | |
| NUDOCS 9501200249 | |
| Download: ML20080F404 (5) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 67 TO FACILITY OPERATING LICENSE NO. NPF-37, AMENDMENT NO. 67 TO FACILITY OPERATING LICENSE NO. NPF-66, AMENDMENT NO. 57 TO FACILITY OPERATING LICENSE NO. NPF-72, AND AMENDMENT NO. 57 TO FACILITY OPERATING LICENSE NO. NPF-77 COMMONWEALTH EDIS0N COMPANY BYRON STATION. UNIT NOS. 1 AND 2 BRAIDWOOD STATION. UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-454. STN 50-455. STN 50-456 AND STN 50-457
1.0 INTRODUCTION
In a letter of August 13, 1993, as supplemented on September 15, 1993, September 16, 1993, December 17, 1993, January 19, 1994, February 11, 1994, and February 24, 1994, Commonwealth Edison Company (Comed, the licensee),
submitted an amendment request for Operating Licenses NPF-72 and NPF-77 for Braidwood Station, Units 1 and 2, and NPF-37 and NPF-66 for Byron Station, Units 1 and 2, proposing steam generator (SG) tube sleeving in accordance with the (1) Westinghouse (M), and (2) Babcock and Wilcox Company (B&W) processes.
The January 19, 1994, and February 11, 1994, supplements submitted additional and clarifying information specifically for Braidwood and Byron in support of the original request. The December 17, 1993, supplement transmitted a reexamination by H of the sleeve repair / plugging limit using the design criteria in lieu of the repair criteria and determined that the through-wall plugging limit for the four units should be 40-percent and identified the material in the submittal that was pertinent for the review of Byron and Braidwood units. The January 19, 1994, supplement converted data from 7/8-to 3/4-inch diameter tubing and supplied additional corrosion test results suitable for the post-weld heat treatment (PWHT) of laser welds. The February 11, 1994, supplement lists the current status on the installation and inspection of laser-welded sleeves.
The M process consists of a laser welding technique to secure a sleeve inside a SG tube to become the primary barrier within a degraded tube.
The technical justification supporting the H process is given in WCAP-13698, Revision 1,
" Laser Welded Sleeves for 3/4-Inch Diameter Tube Feedring-Type and Westinghouse Preheater Steam Generators," and is supplemsnted by the December 17, 1993, and January 19, 1994, submittal s.
The staff reviewed those portions of WCAP-13698, Revision 1, that pertained to Byron and Braidwood SG.
9501200249 950106 DR ADOCK 0500 4
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.. The B&W process uses a kinetic welding technique to secure the sleeves inside SG tubes. Technical justification supporting the B&W process is given in BAW-2045 PA, Revision 1, " Recirculating Steam Generator Kinetic Sleeve Qualification for 3/4-Inch OD Tubes," and is supplemented by the December 17, 1993, and January 19, 1994, submittals.
The staff issued Amendment No. 58 to the Byron Technical Specifications (TS) and Amendment No. 46 to the Braidwood TSs on March 4, 1994.
Included among the amendments was the staff's Safety Evaluation (SE) of the sleeving proposal. The March 4,1994, amendment granted the proposed sleeving methods contingent upon four conditions (Items 1. - 4.) below:
1.
Amend the license to reflect a primary-to-secondary leakage limit of 150 gpd.
2.
Amend the Byron and Braidwood operating licenses to reflect an inservice inspection of a minimum of 20 percent of installed sleeves for axial and circumferential indications at the end of each operating cycle.
In the event that an imperfection of 40 percent through-wall or greater depth is detected, an additional 20 percent (minimum) of the unsampled sleeves would have to be inspected, and sh A d an imperfection of the unsampled sleeves (be) detected in the second 2 ample, all remaining sleeves would be required to be inspected. The inservice inspection is required until the licensee demonstrates the corrosion resistance for laser-welded and kinetically welded joints in tubes that bound the material properties of the tubes installed in the Syron and Braidwood steam generators.
If conformance with the requirements of the plant TSs for tube structural integrity is not confirmed, the tubes containing the sleeves in question shall be removed from service.
3.
Add a condition to the license to conduct additional corrosion testing to establish the design life for the kinetically or laser welded sleeved tubes in the presence of a crevice. The testing should: determine the effects that material microstructure, chemistry, and joint crevices will have on primary water stress corrosion cracking (PWSCC) initiation and growth; bound the material conditions that exist in the Byron and Braidwood steam generators; and include the associated stress intensity values.
4.
Perform post-weld heat treatment at 1400 *F minimum soak temperature with a 5 minute minimum soak time on freespan kinetically or laser welded joints until additional supporting data becomes available.
The staff required Comed to submit the required amendments to Byron and Braidwood operating licenses and TSs within 90 days of issuance of Amendment No. 58 to the Byron TSs and Amendment No. 46 to the Braidwood TSs. By letter to the staff on February 24, 1994 Comed committed to the additional amendments as required by the staff.
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- 2.0 EVALUATION By letter dated June 3, 1994, Comed submitted a request to amend Operating Licenses NPF-37 and NPF-66 for Byron Station, Units 1 and 2, and Operating Licenses NPF-72 and NPF-77 for Braidwood Station, Units I and 2, and Appendix A, Technical Specifications to these Operating Licenses to amend the Steam Generator Primary-to-Secondary Leakage Limits, and amend the inservice inspection requirements as they pertain to inservice inspections of steam generator tubes sleeved by either kinetically welded or laser welded sleeving methods.
The staff has reviewed the licensee's basis for revising the Byron and Braidwood operating licenses and TSs and has determined that the proposed changes are consistent with the commitments made by Comed for the four contingencies identified in Section 1.0 of this SE.
Item I is acceptable because the 150 gpd primary-to-secondary leakage limit is more conservative than the 500 gpd it replaces. The leakage limit ensures that any dosage contributed from a potential SG tube leak will be considerably lower than dosage specified in 10 CFR Part 100. Therefore, the 150 gpd lower limit is more conservative.
Item 2 is acceptable because it increases the sample size for the inservice inspection of the sleeves to ensure that the structural integrity of the sleeves and the pressure boundary are maintained. The revised TSs require that the additional inspections continue until the corrosion resistance of the welded joints is demonstrated. This testing will provide additional certainty that the sleeved tubes will not leak. The final revision, Item 3, is also acceptable because the corrosion testing program will establish sleeve design life and corrosion resistance to confirm structural integrity of the SG tubes. The licensee has committed to perform a corrosian testing program and submit the result to NRC for approval. The licensee will remove the sleeved tubes from service if the tube structural integrity is not confirmed.
Item 4 is not required to be incorporated into a license condition or into the TSs. Therefore, the licensee will address Item 4 by incorporating the requirements for post-weld heat treatment into the appropriate sle?ving installation procedures. This is acceptable to the staff.
The staff has reviewed the licensee's basis for amending the Byron and Braidwood operating licensees and TSs, and has determined that Comed has met the commitments stated in their February 24, 1994, letter.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendments. The State official had no comments.
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4.0 ENVIRONMENTAL CONSIDERATION
The amendments change 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 change surveillance requirements. The NRC staff has determined that the amendments involve 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 the amendments involve no significant hazards censideration, and there has been no public comment on such findings (59 FR 51613). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment l
need be prepared in connection with the issuance of the amendments.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
J. Medoff R. Assa Date: January 6, 1995 l
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D. L. Farrar l A copy of the Safety Evaluation is also enclosed. The Notice of Issuance will be included in the Commission's biweekly Federal Reaister notice.
Sincerely, original signed by Ramin R. Assa, Project Manager Project Directorate III-2 Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation Docket Nos. STN 50-454, STN 50-455, STN 50-456, STN 50-457
Enclosures:
1.
Amendment No. 67 to NPF-37 2.
Amendment No. 67 to NPF-66 3.
Amendment No. 57 to NPF-72 4.
Amendment No. 57 to NPF-77 5.
Safety Evaluation cc w/encls:
see next page DISTRIBUTION:
Docket File PUBLIC PDIII-2 r/f (2)
J. Roe R. Capra J. Medoff C. Moore (2)
R. Assa G. Dick OGC D. Hagan G. Hill (8)
C. Grimes ACRS (4)
OPA OC/LFDCB L. Miller l
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GDICK f// w T/6l7 RCAPRA w DATE 17/6/94 12 57/94 12/J294 12/d/94 32/ofo/9s f
OfflCIAL RECORD COPY
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