ML20168A594
| ML20168A594 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1977-058-00 | |
| Download: ML20168A594 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
132958 Date:
December 11, 1977
Title:
Complete Loss of Offsite Power Occurs at Palisades The failure sequence was:
- 1. With the reactor at 100% power, the "R" switchyard. bus de-energized because of a spurious signal from the bus stripping relay, resulting in a complete loss of off site power and consequent loss of main condenser cooling.
- 2. The reactor was manually tripped.
- 3. Both diesel generators started and provided power to safety-related equipment.
Corrective action;
- 1. The "R" bus tripping scheme was modified to minimize loss of the bus due to spurious action of the "R" bus stripping relay.
The specific cause of the stripping relay trip had not been determined.
Design purpose of failed system or component:
- 1. Off-site 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 power source.
Unavailability of systexh per WASH 140G: *loss of offsite power:
2 x 105 1_hr Unavailability of component per WAS11 1400:*
Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1.
Reactor at Spurious stripping Reactor Both diesel One of two 100% power relay signal trip
)generators auxiliary feed-results in trip start and water pumps pro-of switchyard bus assume safety-vide AFW to R and consequent related loads steam generators loss of offsite for reactor cooling power and loss of (LER does not condenser cooling specify which pump was used).-
Potential Severe Core Damage No Yes Yes.
.No NSIC. 132958-ý Actual Occurrence for Complete Loss of Offaite Power at Palisades
Loss of Of f site Power Turbine Generator Runs Back and Assumes House Loads Emer-gency Power Auxiliary Feedwater ani Secondary Heat Removal d
P0EV Demanded P0EV or P0EV Isola-tion Valve Closure High Pressure Inj ectionL Long Term Core Cooling Potential Severe Core Damage No Sequence No.
2 3
4 5
6 7
8 9
10 11 12 13 NSIC 132958 -
Sequence of Interest for Complete Loss of Offsite Power at Palisades
- Not included in mitigation procedures.
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
132958 DATE OF LER:
December 21, 1977 DATE OF EVENT:
December 11, 1977 SYSTEM% INVOLVED:
off-site power COMIPONENT INVOLVED:
switchyard bus "R" CAUSE:
spurious stripping relay signal SEQUENCE OF INTEREST-loss of of fsite power ACTUAL OCCURRENCE:
reactor trip with loss of offsite power REACTOR NAMIE:
Palisades DOCKET NUMIBER:
50-255 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
.805 MWe REACTOR AGE:
6.8 yr VENDOR:
Combustion Engineering ARCHITECT-ENiGINEERS:
Bechtel OPERATORS:
Consumers Power Co.
LOCATION:
5 =Uiew.:.aoutb. 4-South Haven, Mich.
DURATION:
N/A PLANT OPERATING CONDITION:
100% power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (.b) failed to start; (Omade inoperable; (d) __________
DISCOVERY METHOD:
during operation COýDfl-ENT:
See also 132943