ML19347C764
| ML19347C764 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 11/17/1975 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| References | |
| AO-24-75, NUDOCS 8102170005 | |
| Download: ML19347C764 (2) | |
Text
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t ABNORMAL OCCURRENCE REPORT Big Rock Point Plant 1.
Report No: A0-24-75, Docket 50-155 2a.
Report Date: November 17, 1975 2b.
Occurrence Date: About July 1975, classified A0 on November 6,1975 3
Facility: Big Rock Point Plant h.
Identification of Occurrence:
Improperly authorized addition of load to safety-related 480 volt bus 2A.
5 Conditions Prior to Occurrence: Steady state power operation.
6.
Description of Occurrence: During review of a proposed additional load on breaker 52-2A-63 circuit in October 1975, the question of design analysis was raised on the addition of the breaker and the new security system load on or about July 1975 Subsequent review on November 6,1975 revealed that no design analysis had been done.
7 Designation of Apparent Cause of Occurrence: Failure of Administrative Controls Based on the problems associated with A0-22-75 and this AO, it is concluded that a weakness exists in the facility change classification system and the screening and reviewing of facility changes just prior to the implementation stage. This weakness has resulted in failures to determine safety-related interfaces. This cause has been compounded by the plant "Q" list not being fully developed.
8.
Analysis of Occurrence: Postulated loss of the 2A bus due to uncoordinated tripping or excessive load would incapacitate several redundant safety-related pieces of equipment and the station battery charger. However, a preliminary analysis on November 6,1975 at 0830 based on actual circuit loads indicates considerable margin for load and is not of concern at this time. A tripping coordination study is required.
9 Corrective Action:
a.
A circuit design analysis will be performed by engineering support groups to fully justify the existing circuit configuration.
b.
As 'an interim measure until the action described in e and d below is completed, the plant staff will consider every facility change as safety-related until deemed otherwise by Plant Review Committee action just prior to authorization of implementation of the facility work.
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c.
A more detailed "Q" list is being developed.
d.
Corporate and plant procedures relating to modification control vill be appropriately revised to minimize the possibility of recurrence as well as correct other discrepancies.
10.
Failure Data: Similar and related to A0-22-75 s
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