ML18046A753
| ML18046A753 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/25/1981 |
| From: | Johnson B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-1.C.1, TASK-TM GL-81-04, GL-81-4, NUDOCS 8106300297 | |
| Download: ML18046A753 (2) | |
Text
consumers Power company-General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201 * (517) 788-0550 June 25, 1981 Director, Nuclear Reaction Regulation Att Mr Dennis M Crutchfield, Chief Operating Projects Branch No 5 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 LICENSE DPR PALISADES PLANT -
EMERGENCY.PROCEDURES AND TRAINING FOR STATION BLACKOUT EVENTS (GENERIC LETTER 81-04) RESPONSE By letter dated February 25, 1981 (Generic Letter 81-04), the NRC requested a review of the Palisades plant's capability to mitigate a loss of off-site power coupled with a loss of all on-site AC power.
It also requested a review of procedures and training pertinent to this event and identification
. of additional needs in this area.
At the outset, it must be pointed out that to get a true total loss of AC power at Palisades, multiple independent DC system failures would also have to occur, since the instrument and preferred AC busses are supplied from the batteries through inverters.
Since DC system failures have been excluded from station blackout considerations, we do not believe that loss of the instrument and preferred AC busses simultaneous with loss of all other on-site and off-site AC power sources was intended by the staff.
Therefore, we have interpreted the term "station blackout" to only include loss of all off-si te AC power and the emergency diesel generators.
The existing design of the Palisades plant provides inherent capability to withstand a station blackout for significant periods of time without fuel damage.
Without any operator action, decay heat can be removed for up to _.., 30 minutes through the main steam line relief valves with the PCS in natural circulation.
The limiting consideration in this condition would be the inventory of water in the secondary sides of the steam generators.
This time can be gr~atly: extended through initiation of auxiliary feedwater with the steam.driven auxiliary feedwater pump.
Because preferred/instrument AC and DC power* would remain available, operators would retain normal indication of plant status and auxiliary feedwater controls.
A total loss of AC power on-site is not now and has never been a design basis event for the Palisades Plant, and we see no need for it to become one.
A total loss of AC power can only result from multiple independent failures of off-site lipes ~dtor1breakers in conjunction with the simultaneous loss of 1
8 1U,630 Sjl.9"1
~-
2 both independent emergency diesel generators.
By the NRC staff's own estimates, the probability of cpre damage from a station blackout in which AC power is not restored is essentially the same as the probability of core damage resulting
- ~--
from a LOCA.
When the probability of AC power restoration is also considered, the.staff has estimated the reduction in core damage probability to be another order of magnitude.
Therefore, in view of the inherent plant capability to withstand a station black-out for significant periods without core damage, the low probability of occur-rence of a station blackout, andthe high probability that some source of AC power can be restored, we feel that consideration of this issue as a design basis event for the Palisades Plant is unwarranted.
However, Consumers Power has deter-mined that adequate capability exists to mitigate a station blackout event.
Oper-ating procedures exist and operator training has been conducted which address mitigation of station blackout events.
Annual requalification including simulator training is currently provided for actions required to mitigate station blackout events.
Therefore, Consumers Power plans no further actions to address station blackout events for the Palisades Plant other than those that may be required in modifying existing procedures to implement the PWR Owner's Group Emergency Procedure Guidelines in accordance with NUREG-0737 Item I. C.1.
Brian D Johnson Senior Licensing Engineer CC Director, Region III, USNRC i
I NRC Resident Inspector-Palisades