ML042960319

Information Needed for Risk Analysis of Loss of Offsite Power Events

ML042960319
Person / Time
Site:	Palo Verde
Issue date:	06/17/2004
From:	David Loveless NRC Region 4
To:
References
FOIA/PA-2004-0307
Download: ML042960319 (2)

Text

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1. Obtain copies of EOPs, AOPs, and SOP relating to the following events that were in effect at the time of the event

a. Reactor trip and post trip

b. LOOP

c. Station blackout

d. Recovery of power to the switchyard

e. Recovery of power to the safety buses

f. Battery life extension (load shedding)

g. Operation of alternate power sources, including blackstart sources

2. Obtain electrical distribution drawings showing:

a. Switchyard

b. Safety buses and loads

c. BOP buses and loads

3. List of operator actions (inside and outside the control room) and time estimates needed to recover:

a. Offsite power to the safety buses

b. Start alternate power sources

c. Failed equipment

d. Unavailable equipment in test and maintenance

4. Plant configuration prior to the initiating event:

a. List of equipment out-of-service for test and maintenance

b. Electrical power lineups

c. Battery lifetimes with proceduralized life extension (load shedding)

d. Reactor coolant pump seal type

e. Backup/alternate power sources, including blackstart capability

5. Post trip conditions:

a. Failed equipment

b. Operator performance issues

c. Equipment performance issues (degradations)

d. Status of MFW and PCS (e.g., did the loss of power effect BOP buses?)

e. Lifting of PORV/SRV(s)

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6. Offsite power recovery

a. Actual time when offsite power was stable (voltage and frequency) to carry loads to mitigate RCP seal and stuck open SRV LOCAs and to bring the plant to cold shutdown.

b. How and when would the control room know at the earliest time that offsite power was stable to carry these loads.

c. Actual time when offsite power was restored to the first safety bus.

d. Estimate of the earliest time when offsite power could have been restored to the first safety bus given a postulated station blackout or core damage sequence, such as the loss of one bus and the failure of a key component powered from the remaining bus. NOTE: This time will be confirmed by electrical and human reliability experts based on information provided above.