ML20113B661
| ML20113B661 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 03/21/1985 |
| From: | Hufham J TENNESSEE VALLEY AUTHORITY |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-85-157-000 NCR-2454, PT21-85-157, PT21-85-157-000, NUDOCS 8504110333 | |
| Download: ML20113B661 (2) | |
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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 374o1 400 Chestnut Street Tower II March 21, 1985 BLRD-50438/83-5SS WR 25 P 2
- 3 <l BLRD-50-439/83-45 U.S. Nuclear Regulatory Cmmission Region II l
Attn:
Dr. J. Nelson Grace, Regioml Administrator 101 Marietta Street, NW, Saite 2900 Atlanta, Georgia 30323
Dear Dr. Grace:
BELLEFCNTE NUCLEAR PLANT INITS 1 AND 2 - FRONT (DVEIB SEP ARATED FROM B AILEY METER MODULES - BLRD-50-43 8/83-52, BLRD-50-439/83 REVISED FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector Linda Watson on October 4, 1983 in accordance with 10 TR 50.55(e) as NCR 2454.
This was followed by our interim reports dated November 1, 1983 and Janmry 25 and April 18, 1984.
Our fimi mport was autraitted on November 27, 1984.
Enclosed is our revised fimi report. We consider 10 CFR Part 21 applicable to this deficiency.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours,
TENNESSEE VALLEY AUrHORITY f
f(3. W. Huf ham, Mana ger Licensing and Regulations helceure ce (Enclosure ):
Hr. James Taylor, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Cmmission Washington, D.C.
20555 Records Center Institute of Nuclear Power Operations
/
1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgta 30339 H. B. Barkley 205 Plant Project Services P.O. Box 10935 Lynchburg, VA 24506 4935 1
An Equal Opportunity Employer
ENCLWURE BELLEFQiTE NUCLEAR PLA!If UNITS 1 AND 2 FRONT COVERS SEP ARATED FROM BAILEY lETER MODULES BLRD-50-438/83-52, BLRD-50-43 9/83-45 NCR 2454 10 7R 50.55(e)
REVISED FINAL REPORT Deseription of Deficiency While inspecting Bailey Meter Company modules at Bellefonte Nuclear Plant (BLN),
TV A's Office of Construction (OC) personnel discovered that front cover plates for several class 1E modules in control cabinets for the mnnuclear instru-mentation (NNI) and essential controls instrtmentation.(ECI) systes had become separated from the frame body of the module. The front cover plate is attached to the frame body by means of tm spot welds at the top and bottom of the front co ver plat e.
These spot welds had been broken causing the front plate cover to separate from the module.
The root cause of this paoble was inadequate process control by the vendor.
This is documented in Babcock and Wilcox (B&W) letter D-4981. The vendor failed to supply sufficient current for the second and subsequent spot welds which secure the front cover to the module. This insufficient current resulted in smaller than acceptable weld nugget sizes.
A secondary contributor to failure of the front cover welds was the excessive forces required to mmove the module. This excessive force resulted f rca a misalignment of the back plane contacts.
Safety Icnlic ations The spot welds on the front cover plates of the class 1E control modules have become separated from the frame body. This will allow the modules greater movement inside the cabinets. Unrestricted movement of the modules inside the cabinet could lead to the possible short-out of wiring in the modules or the module-to-cabinet plug-in coming out of the cabinet. The 1oss of essential safety-related controls would adversely affect the safe operacion of the plant.
Correc tive Ac tions The modules were returned to the vendor for rework. The vendor has completed the rework and returned the modules to BLN.
For the smaller than acceptable weld sizes, the vendor revised his welding procedure to ensure that adequate current is supplied during the welding process so that acceptable welds are produced.
To address the misalignment probim, TV A will realign the back plate contacts using a special alignment tool in accordance with the vendor's mcommendations by March 22, 1985.
After the sutaission of our final report on this deficiency, IMW mpresentatives met with TVA personnel at a BLN site meeting on December 18, 1984. During this meeting, B&W and TV A representatives agreed that maintenance instructions governing the use of the special alignment tool are rot necessary and will not be provided. Consequently, no mvision of site maintenance procedures is required.
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