ML20084N435
| ML20084N435 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek, Callaway, 05000000 |
| Issue date: | 05/23/1983 |
| From: | Seiken S STANDARDIZED NUCLEAR UNIT POWER PLANT SYSTEM |
| To: | Jay Collins, James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| REF-PT21-83-880-000, REF-PT21-83-882-000 10CFR-50.55E, PT21-83-882, PT21-83-882-000, SLNRC-83-028, SLNRC-83-28, NUDOCS 8306030220 | |
| Download: ML20084N435 (3) | |
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SNUPPS Standardized Nuclear Unit Power Plant System 5 Choke Cherry Road May 23,1983 Rockville, Maryland 20850 SLNRC 83 028 FILE: 0491.10.2 SUBJ: Final Report: DS-416 Reactor Trip Switchgear Undervoltage Attachment (SDR 83-07)
Mr. James G. Keppler Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 Mr. John T. Collins Administrator, Region IV U.S. Nuclear Regulatory Commission Suite 1000, Parkway Central Plaza Arlington, Texas 76012 Docket Nos. STN 50-482 and STN 50-483 Gentlemen:
On April 21, 1983, NRC Region III and Region IV representatives were informed by SNUPPS Staff (R. White, M. Fletcher) of a deficiency in Callaway and Wolf Creek Type DS-416 Reactor Trip Switchgear breakers manufactured by Westinghouse (Switchgear Division, East Pittsburgh).
In the April 21 notifications, it was explained that due to a design discre-pancy, a retaining ring may become disengaged from a pivot shaft in the DS-416 undervoltage attachment. Refer to the attached sketch for details.
Disengagement of the retaining ring allows the pivot shaft to move axially such that one end of the shaft may come out of the shaft guide hole in the frame of the undervoltage attachment. Under these circumstances the undervoltage attachment may fail to operate and the reactor trip breaker might not open on automatic demand from the reactor protection system.
The deficiency was also reported by Westinghouse on April 20, 1983 pur-suant to the requirements of 10CFR21.
The cause of the problem has been reported by Westinghouse as follows:
the design width of the retaining ring was increased in 1972, but the width of the mating groove in the pivot shaft was not similarly widened to be consistent with the retaining ring modification; consequently the wider retaining rings do not seat properly in the existing pivot shaft grooves.
To correct the problem, all DS-416 reactor trip breaker undervoltage attachments at Callaway and Wolf Creek will be replaced. The replace-ment DS-416 attachments will have modified (widened) grooves to accommo-date the new retaining rings. The DS-416 undervoltage attachments will 0500$b2 l
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SLNRC 83 028 Page Two be replaced at each site prior to fuel loading. Westinghouse also reports that, in addition to revising manufacturing drawings, quality control pro-cedurer have been modified to assure that critical design dimensions are maintained during manufacture of the replacement DS-416 undervoltage attachments.
It will be verified by inspection that the replacement under-voltage attachments meet part number and critical dimensional requirements.
This report should be considered the final report concerning the DS-416 reactor trip breaker undervoltage attachment deficiency. The NRC will be informed should there be any new developments concerning this issue.
Very truly yours, d%
s S. J.
eiken Manager, Quality Assurance RPW/dck/9b9
Attachment:
Sketch, Undervoltage Attachment cc:
D. T. McPhee, KCPL G. L. Koester, KGE D. F. Schnell, UE H. W. Roberds, USNRC/WC J. H. Neisler, USNRC/ Cal H. M. Wescott, USNRC Region III Richard DeYoung, Director I&E Record l
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