ST-HL-AE-5779, Forwards Response to NRC Requesting Addl Info on Thimble Guide Tube Nut Replacement
| ML20198Q572 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 11/06/1997 |
| From: | Thomas S HOUSTON LIGHTING & POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ST-HL-AE-5779, TAC-M98968, TAC-M98969, NUDOCS 9711120255 | |
| Download: ML20198Q572 (3) | |
Text
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y The Light company Howton'ligMmg & Power South Texas Project Electric Generating Station P.O. Dos 289 Wadsworth. Texas 77483 November 6,1997 ST-HL-AE-5779 File No.: G25 10CFR50.59 U. S. Nuclear Regulatory Commission Attention: Document Control Desk
. Washington, DC 20555 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Response to Request for Additional Information Regarding Thimble Guide Tube Nut Renlacement (TAC Nos. M98968 and M98969)
Reference:
Letter from Thomas W. Alexion, NRC, to William T. Cottle, HL&P, dated October 15,1997 (3T-AE-IIL-94971)
The referenced letter requested additional information regarding thimble guide tube nut replacement which was the subject of a South Texas Project Unreviewed Safety Question Evaluation being reviewed by the NRC Staff. The response to the request is attached.
If you should have any questions concerning this matter, please call Mr. A. W.
Ilarrison at (512) 972-7298 or myself at (512) 972-7162.
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f S. E. Thomas
- Manager, Design Engineering DNB/
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- Houston 1.ighting & Power Company ST-IIL-AE-5779 South Texas Project Electric Generating Station File No.: G25 Page 2-c:
Ellis WL Merschoff Rufus S. Scott Regional Administrator, Region IV Associate General Counsel U. S. Nuclear Regulatory Commission Houston Lighting & Power Company 61l'Ryan Plaza Drive. Suite 400 P. O. Box 61067 Arlington, TX -76011-8064 Houston, TX 77208 Thomas W. Alexion Institute of Nuclear Power Project Manager, Mail Code 13H3 Operations - Records Center U. S. Nuclear Regulatory Commission 700 Galleria Parkway Washington, DC 20555-0001 Atlanta, GA 30339-5957 David P. Loveless Dr. Bertram Wolfe Sr. Resident inspec -
15453 Via Vaquero c/o U. S. Nuclear Regulatory Comm.
Monte Sereno, CA 95030 P. O. Box 910 Bay City, TX 77404-0910 Richard A. Ratliff Bureau of Radiation Control J. R. Newman, Esquire Texas Departmer,t of Health Morgan, Lewis & Bockius 1100 West 49th Street 1800 M Street, N.W.
Austin, TX 78756-3189 Washington, DC 20036-5869 J. R. Egan, Esquire M. T. Ilardt/W. C. Gunst Egan & Associates, P.C.
City PuNic Service 2300 N Street, N.W.
P. O. Box 1771 Washington, D.C. 20037 San Antonio, TX 78296 J. C. Lanier/M. B. Lee U. S. Nuclear Regulatory Commission City of Austin Attention: Document Control Desk Electric Utility Department Washington, D.C. 20555-0001 721 Barton Springs Road Austin, TX 78704 Central Power and Light Company ATTN: G. E. Vaughn/C. A. Johnson P. O. Box 289, Mail Code: N5012 -
Wadsworth, TX 177483 nwnamemusc mm, m =m
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Attachment ST-ilL AE-5779 Page 1 of 1 Response to Request for Additional Information Recardine Thimble Guide Tube Nut Renlacement 1.
The split nut material is specified on page 3 of the 50.59 Safety Evaluation Summary as " ASTM A479 type 316,316L." This appears to specify two different grades with different material strengths. Please clarify.
South Texas Project Response:
The NRC Staffis correct to note that two different grades were specified for the split nut.
Either grade is acceptable for the intended design purpose. The split nuts were fabricated from available inventory stocked in South Texas Project's warehouse at the time. ASTM A479 austenitic steel comes in a variety of grades. The minimum yield strength of any grade is 25 ksi (for grade 316L). Grade 316L meets the yield strength criterion assumed in the South Texas Project split nut design. Grade 316 is also acceptable since it has higher yield strength.
2, Page 3 of the 50.59 Safety Evaluation Summary also specifies the cap screw material as " ASTM F837 condition CW." This speci6 cation is evidently erroneous or incomplete. Additionally, ASTM F837M is for metric fasteners and is not in agreement with Figure 2 of the analysis which clearly shows English system fasteners.
Please clarify.
South Texas Project Response:
There are 3 different group and condition combinations recognized under ASTM F837, namely Group 1, condition AF; Group 1, condition CW; and Group 5, condition IIT. Since condition CW occurs only in Group 1, the group is understood to be I when " ASTM F837 condition CW" is speci6ed. To clarify, the intended material specification given in the 50.59 Safety Evaluation Summary is ASTM F837, Group 1, Condition CW.
Material specification ASTM F837, which is given in English units, was specified for the design of the cap screw fasteners. Material specification ASTM F837M, which is given in metric units, was not specified for the design.
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