ML19329B889

Deficiency Rept Re Control Rod Drive Sys Trip Circuit Breaker Cabinets:During Insp,Cabinet Welds Found Shorter than on Shaker Table Test Qualified Cabinet.Addl Weld Length to Be Added

ML19329B889
Person / Time
Site:	Davis Besse
Issue date:	02/24/1978
From:	Roe L TOLEDO EDISON CO.
To:
Shared Package
ML19329B880	List: ML19329B889
References
REF-PT21-78-032-000 417, NUDOCS 8002060887
Download: ML19329B889 (1)

Text

-

,

'

~Fabrecry 24, 1978 m

Serial No. 417 g;;gf g. ratgoo Docket No. 50-346 m wacn LOWELL E. Rce License No. NPF-3 v.co Pres dent

. ... .. n c ...,u...s wei ass.sm Mr. Janes G. Keppler Regional Director, Region III Of fice of Inspection & Enforcement -[() ~~ h h ~OOO r U. S. Nuclear Regulatory Consission 799 P4osevelt Road Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

In accordance with ICCFR Part 21.21(b), this is a report of a defect in ec=ponents installed in the Davis-Besse Nuclear Pcwer Station Unit No. 1. The cocponents involved are the control rod drive system trip circuit breaker cabinets.

These circuit breaker cabinets were supplied by Babecek & Wilcox.

The defect involves the weld used in the nounting of these cabinets.

Recent inspection shows that the velds (both inside and outside the cabinets) are of a shorter length than those used on the cabiaet that was qualified by a .;haker table test. AlthouSh the enisting weids may, in fact, he adequate for this installa-tion (the shaker table test was more severe than required to qualify the cabinets for Davis-Besse Unit No. I service), we consider the existing installation to be an unacalyted installatien. The safety hazard thich could be created by this defect is, if the cabinet installation failed during a seismic event, it could beccne impossible to trip the centrol rod drive trip breakers. This capability is required by General Design ~ Criterion 19. There are four cabinets (C4603, C4606, C4612 and C46C6) containing this defect at Davis-Eesse Unit No. 1.

On February 21, 1973, the deviation was evaluated by Toledo Edison to be a defect.

This matter was repcreed to your Mr. T. Tanbling on February 21, 1973.

The corrective action to be taken is to add additional weld length to conform with

! the design that was qualified by test. The corrective action will include deener;;izin; the breaker cabinets to perform welding inside the cabinets. Until this velding has been ccmplated, the control room operators will be provided with an e=ergency procedure to locally trip the feeder breakers on the EE and EF buses to provide a backup in the event more than two of the feur control rod drive trip circuit breakers fail to open as designed. We expect to complete this additional velding during the April outage.

This information has not been given to other licensees or purchasers.

Yours very truly, j h y

/ '

a _ -

n .-.-- ,.....n

.I L1, iu

.

THE TOLEDO ED SON CCMPANY EDESCN PLAZA 300 MACISCN AVENUE TOLEGO. CH:0 43652

-

---

. .. . _ _ . . . _ - _ _ _ . _ . . _ _ . . ,.

1 I