ML20082R442
| ML20082R442 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 12/05/1983 |
| 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-R-30, NUDOCS 8312130167 | |
| Download: ML20082R442 (3) | |
Text
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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II
[eddbkr$5,1983 BLRD-50-438/83-35 BLRD-50-439/83-31 U.S. Nuclear Regulatory Commission 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 - B&W PLANT INTERNAL BOLT FAILURES
- BLRD-50-438/83-35, BLRD-50-439/83 SECOND INTERIM HEPORT The subject deficiency was initially reported to NRC-0IE Inspector Linda Watson on May 13, 1983 in accordance with 10 CFR 50.55(e) as NCR R-30.
This was followed by our interim report dated June 13, 1983 Enclosed is our second interim report. We expect to submit our next report by July 24, 1984.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY k.
L. M. Mills, Manager Nuclear Licensing Enclosure oc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcemt it U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center (Enclosure)
Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 Ml'!CI A L COPY 8312130167 831205 PDR ADOCK 05000438 M"7 T'
S PDR Il 1983-TVA SOTH ANNIVERSARY An Equal Opportunity Employer
ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 B&W PLANT INTERNAL BOLT FAILURES BLRD-50-438/83-35, BLRD-50-439/83-31 10 CFR 50.55(e)
NCR R-30 SECOND INTERIM REPORT Description of Deficiency The Babcock and Wilcox (B&W) Owners Group has opened issue R-30 " Internals Bolting Failures" documenting a potential safety concern with B&W plants.
Specifically, there have been failures of A-286 bolts used in various reactor internals applications at Oconee-1, Rancho Seco and Crystal River-3 Although B&W contends that the problem is not applicable to Bellefonte, TVA has questioned B&W's determination and is awaiting a reply from B&W. Until such time that R-30 is determined to not be a concern at Bellefor.te, TVA considers the condition to be a potentially reportable nonconformance. Consequently, this NCR is intended to track the potential concern for Bellefonte.
Interim Progress B&W's review of the Bellefonte reactor internals joint design identified five joints that utilize A-286 bolting material. These joints are:
1.
Plenum lug to cover.
2.
Vent valve to core support assembly.
3 Core support lug.
4.
Plenum cylinder to upper grid.
5.
Colume weldment to upper grid.
Peak stress levels for these joints were estimated by multiplying the sum of the long-term preload and operating stress levels by an estimated stress concentration factor. The resulting peak stress levels for joints 1 and 2 are well below the actual yield. Joint 3 has low stress but the high stress concentration factor under the bolt head results in a relatively high peak stress value. The peak stresses for joints 4 and 5 are much greater than the actual yield stress.
B&W has performed n preliminary review of the safety implications assuming failure of the two overstressed joints (4 and 5). The results of this review indicate that the plant could be safely operated and/or shut down for detailed inspection without endangering the health and safety of the public. Regardless of this, TVA believes that replacing these bolts with bolts of another material (such as alloy X750 HTH) before plant operation will ultimately reduce platit downtime and personnel radiation exposure. While the bolts for ~ joints
1, 2, tnd 3 may provida catirractory s;rvica for tha lifa of tha pinnt, TVA b;11 cms thtt it la prudent to replica th s3 bolts with bolts of another material (su'h as alloy X750 HTH) and of a design which may be inspected without. isassembly of the equipment to verify integrity.
TVA has requested B&W to proceed with replacement of all A-286 bolts for the five joints listed above. We will provide a final report upon revicw and approval of the corrective action plan and/or final determination of the safety significance of the deficiency.