ML20100P418
| ML20100P418 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 11/27/1984 |
| From: | Hufham J TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-84-548-000 NCR-2454, PT21-84-548, PT21-84-548-000, NUDOCS 8412140227 | |
| Download: ML20100P418 (2) | |
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BLRD-50-438/83-52 l -BLRD-50-439/83-45
's U.S. Nuclear Regulatory Commission Region I~
Attn: lir. Janes P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanti, Georgia 30323
DearMr.'O'Reilly:
m BELLEFCNTE NUCLEAR PLANT UNITS 1 AND 2 - FRONT COVERS SEPARATED FROM BAILEY ME1ER MODULES - BLRD-50-438/83-52, BLRD-50-439/83 FINAL REPORT s,
', The subject deficiency was initially reported to NRC-0IE Inspector Lirmia Watson ~on October 4,1983 in accordance with 10 CFR 50.55(e) as NCR 2454. This was followed by our interim reports dated November 1,1983 and January 25 and April 18, 1984. A one-week delay of this submittal was discussed with Inspector P. E. Fredrickson on November 21, 1984. Enclosed is cur _ final report. We consider 10 CFR Part 21 applicable to this deficiency.
If you have an) questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY N
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J. W. Hufham, Manager Licensing and Regulations Enclosure oc (Enclosure):
Mr. Richard C. DeYoung, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center Institute of Nuclear Power Operations 1100 circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339
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H. B. Barkley 205 Plant Project Services P.O. Box 10935 Lynchburg, VA 24506-0935 OFFICIM,( r)py
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ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 '
- FRONT COVERS SEPARATED FROM BAILEY METER MODULES BLRD-50-438/83-52, BLRD-50-439/83-45 NCR 2454 -
FINAL REPORT Description of Deficiency While inspecting Bailey Meter Company modules at Bellefonte Nuclear Plant (BLN),
TVA's Office of Construction (OC) personnel discovered that front cover plates for several class 1E modules in control cabinets for the nonnuclear instru-mentation (NNI) and essential-controls instrumentation (ECI) systems had become separated from the frame body of the module. The front cover plate is attached to the frame body by means of two spot welds at the top and bottom of the front cover plate. These spot welds-had been broken causing the front plate cover to separate from the module.
The root cause of this problem 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 remove the module. This excessive force resulted - from a misalignment of the back plane contacts.
Safety Implications 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 cculd lead to the possible short-out of wiring in the modules or the module-to-cabinet plug-in coming out of the cabinet. The loss of essential safety-related controls would adversely affect the safe operation' of the plant.
Corrective Actions 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 maure that adequate l
current is supplied daring the welding process so that' acceptable welds are l
produc ed.
To address the misalignment problem, TVA will realign these back plane contacts I
that have been documented in this nonconformance report using a special' i
- alignment tool in accordance with the vendor's recommendations by March 22, 1985. TVA is obtaining this tool from B&W and requested that B&W provide -
i maintenance instructions governing the tool's use. TVA will incorporate these instructions into the maintenance procedures used by site personnel. TVA anticipates receipt and approval of these instructions by February 15, 1985.
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