ML20072N270
| ML20072N270 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 07/05/1983 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NCR-BLN-2377, NRC-BLN-2377, NUDOCS 8307150267 | |
| Download: ML20072N270 (3) | |
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I Tllt$tNESSEE! VALLEY AUTHORITY ATL 'CH ATTA NDDurir AC' A Y, NESSEE 374ol 400 Chestnut Street Tower II 83 JUI.12 A 9 : 2 auly 5,1983 BLRD-50-438/83-38 BLRD-50-439/83-33 U.S. Nuclear Regulatory Comission Region II Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - BREAKING OF WELDED STUDS
- BLRD-50-438/83-38, BLRD-50-439/83 FIRST INTERIM REPORT The subject deficiency was initially reported to NRC-0IE Inspector P. E. Fredrickson on June 6,1983 in accordance with 10 CFR 50.55(e) as NCR BLN 2377. Enclosed is our first interim report. We expect to submit our next report by December 19, 1983 In accordance with the specific request of NRC Region II Inspector Paul Fredrickson the following information is provided. TVA has initiated other nonconformances addressing related deficiencies at other TVA nuclear plants.
NCRs BFN BWP 8305, SQN SWP 8305 and WBN SWP 8230 (WBRD-50-390/83-07, WBRD 391/83-06) were written on Browns Ferry, Sequoyah, and Watts Bar Nuclear s
Plants, respectively. These NCRs document the apparent lack of bolt tightening requirements provided to CONST by TVA's Division of Engineering Design (EN DES) for main and miscellaneous steel structures, pipe supports, conduit supports, cable tray supports, HVAC supports, and instrumentation line supports. The SQN NCR has been investigated and it has been determined that torque specifications were given and all potentially affected systems are still qualified for all design loading combinations and design conditions. TVA's evaluation of the BFN and WBN NCRs is still ongoing.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY
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L. M. Mills, nager Nuclear Licensing Enclosure cc: Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission
. V Washington, D.C.
20555 L C0F cc: Continued on page 2 8307150267 830705 983-TVA SOrH ANNIVERSARY PDR ADOCK 05000438 S
PDR An Equal Opportunity Employer
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-2 U.S. Nuclear Regulatory Comunission July 5, 1983 Records Center (Enclosure)
Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 i
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ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 BREAKING OF WELDED STUDS BLRD-50-438/83-38, BLRD-50-439/83-33 10 CFR 50.55(e)
NCR BLN 2377 FIRST INTERIM REPORT
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Description of Deficiency Some of the 1/4-inch welded studs used on seismic conduit supports are breaking during torque-tightening or after a period of time subsequent to tightening. An informal test of approximately 30 studs conducted by TVA's Division of Construction (CONST) personnel indicated a breaking torque of 7-1/2 to 12-1/2 ft-lbs. TVA drawing 4RA0560-X2-13 R6, " Typical Seismic Conduit Support" specifies a minimum torque requirement of 6 ft-lbs. However, TVA's process specification 3.C.S.3(a) specifies a torque value of 5 ft-lb for 1/4-inch studs. This corresponds to the maximum torque value for 1/4-inch studs recommended by the American Welding Society (AWS) Code D1.1.
Stud manufacturers recommend a torque value of no more than 60 percent of the yield strength. For 1/4-inch studs which have a yield strength of 55 kai, 60 percent of 55 kai corresponds to a torque value slightly in excess of 4 ft-lbs. Therefore, the specified minimum torque on the installation drawing is 20-30 percent higher than the maximum torque recommended by the steel manufacturers and AWS Dt.1.
Interim Progress TVA is evaluating the scope of the deficiency and determining the appropriate corrective action by specifying the maximum allowable torque on the bolts.
TVA will provide details of the findings in our next report.
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