ML19319C906
| ML19319C906 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 10/03/1974 |
| From: | BABCOCK & WILCOX CO. |
| To: | |
| Shared Package | |
| ML19319C884 | List: |
| References | |
| NUDOCS 8003040856 | |
| Download: ML19319C906 (1) | |
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$O Report on C?.DCS 3reaker Cabinet Seis=ic Qualification jv
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Thir report, pursuant to 10 CFR 50.53(e) on 'Significant Deficiencies, is to S
document the investigation of the significant deficiency 'in the seis=ic qual-U ification on the Control Rod Drive Control Syste= Trip Breaker Cabinets.
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Identification of Proble=s A reevaluation of the seis=ic qualification of the control rod drive control i
system AC breaker cabinets has found that the attach =ent of the cabinet to the i,
floor is inadequate to withstand the SSE acceleration levels.
1 Analysis l
The. Control Rod Drives are trippad by Loss of Power to the Drive Stators.
Pcwer is interrupted by disengaging either the AC or DC CRD breakers.
Should the I
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breaker function be disabled in some =anner, the Control Rods would have to be driven into the core to shut the reactor down.
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j In the event of an SSE, the AC Breaker Cabinets could, as per the analysis, i
break loose fco= the floor =ounting. With the cabinets unattached, the rando:
i motion of dancing, bouncing, and even falling over could cause accelerations of the breakers that have not been analyzed or damage to the breakers, wiring, or I
connections which could conpro=ise the ability of the breakers to trip the f
control rods. Analyses cannot show that the failure will always be fail safe.
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Therefore, the deficiency in the design of the structural attach =ent of the AC l
Breakers Cabinets to the floor could adversely affect safety.
This i. roble: is t
thus considered to be a Significant Deficiency as par 10 CFR 50.55 (e).
i Corrective Acticn l
'Ihe attach =ent of the AC Breaker Cabinet to the. floor has been redesigned.
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Pending upen the arrange =ent at the particular site, either additional bolts
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will be included or a fillet veld will be added to increase the attachnent strength, l
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l' Each plant is being evaluated on an individual basis.
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