ML20168A593
| ML20168A593 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1977-055-00 | |
| Download: ML20168A593 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
132943 Date:
December 16, 1977
Title:
Complete Loss of Offsite Power Occurs at Palisades The failure sequence was:
- 1. Durimg mormal operatiom with the reactor at 85% power, switchyard-bus "R" became de-energized, causing a complete loss of offsi~te power and resulting in a loss of maim condenser cooling water flow.
- 2. The reactor was manually tripped.
- 3. Both diesel generators started and provided power to safety-related loads.
Corrective action;.
None; the cause of the "R" bus loss was under investigation.
Design purpose of failed system or component:
Of fsite power provides the preferred source of electric power to plant equip-ment when the unit generator is not in operation.
The condenser circulating water pumps are normally powered from the off-site source.
Unavailability of system per WASH 140G:*
loss of of fsite power:
2 x 10-5 /hr Unavailability of component per WASH 1400:
Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1.
Reactor at Switchyard bus "R" Reactor Both diesel One of two auxiliary 85% power de-energized, trip generators. start feedwater pumps pro-resulting in loss and assume vide AFW to steam of offsite power safety-related generators for reactor and loss of con-loads cooling (LER does not denser cooling specify which pump was used)
Potential Severe Core Damage NSIC 132943 -
Actual Occurrence for Complete Loss of Offsite Power at Pali6ades
Loss of Turbine Emer-Auxiliary PORV PORV or High Long Of fsite Generator gency Feedwater and Demanded PORV Isola-Pressure Term Power Runs Back Power.Secondary tion Valvý-
Injection Core and Assumes Heat Removal Closure Cooling House Loads Potential Severe Core Damage Sequence No.
2 3
4 5
6-7 8
9 10 11 12 13 NSIC 132943-- Sequence of Interest for Complete Loss of Offsite Power at Palisades
- Not included in mitigation procedures.
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:.132943 DATE OF LER:
December 16, 1977 DATE OF EVENT.:
November 25, 1977 SYSTEM-INVOLVED:
offsite power COMPONENT INVOLVED:
switchyard bus "R" CAUSE:
bus trip from unknown causes SEQUENCE OF INTEREST:
reactor trip with loss of offsite power ACTUAL OCCURRENCE:
reactor trip with loss of offsite power REACTOR NAIE:
Palisades DOCKZET NU'M1BER:
50-255 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
805 MWe REACTOR AGE:
6.8 yr VENDOR:
Combustion Engineering ARCHITECT-ENGINEERS:
Bechtel OPERATORS:
Consumers Power Cb; LOCATION:
5 mil-es south of goutL Hav~en, Mich.
DURATION:
N/A PLANT OPERATING CONDITION:
85% power SAFETY FEATURE TYPE OF FAILURE:
Ca) inadequate performance; (b) failed to start;
((in)ade inoperable; (d)
DISCOVERY METEOD:
during operation COMMENT;
_. See also 132958