ML20168A735
| ML20168A735 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1978-010-00 | |
| Download: ML20168A735 (4) | |
Text
B-47 4 PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
137384 Date:
March 18, 1978
Title:
Two Makeup Pumps Trip During Testing at Three Mile Island 1 The failure sequence was:
- 1. During performance of the Emergency Sequence and Power Transfer Test, both makeup pumps failed to start after power was restored to their respective buses.
In one case, a lube oil pressure timer relay failed to close, and in the other case, a relay failed to disengage when the pumps initially tripped due to loss of power during the test.
Corrective action;
- 1. The timer relays were to be replaced during the refueling outage which was in existence during the test.
Design purpose of failed system or component:
- 1. The timer relay allows the pump to run for six seconds without normal lube oil pressure while the pump is initially coming up to speed.
- 2. The makeup pumps perform as emergency high pressure injection pumps for LOCA.
Unavailability of system per WASH 1400:*
8.6 x 10-3 Unavailability of component per WASH 1400:
- pump, failure to start:
1 x 10-3/D Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1.
Makeup pumps MU-PIA, MU-PIC Power restored MU-11IA start MU-PIC start MU-PIA, MU-PIC tripped to MU-PIA, nd run and run running and voltage MU-PIC buses on buses for MU-PIA, MU-PIC interrupted for testing during refueling Potential Severe Core Damage No No Yes to I1 No I
No No -
N~o LOCA & unit in shutdown NSIC 137384 -
Actual occurrence for Failure of Two Makeup Pumps During Testing at Three Mile Island 1
Small Reactor Auxiliary High Low Pressure LOCA*
Trip Feedwater and Pressure Recirculation Secondary Injection and LPR/HPI Heat Removal.
Cross-Connect Potential Severe Core Damage No Sequence No.
2 3
4 5
6 7
-I C7%
NSIC 137384 -
Sequence of Interest for Failure of Two Makeup Pumps During Testing at Three Mile Island 1
- With loss of offsite power.
B-47 7 CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
137384 DATE CF LER:
April 5, 1978 DATE OF EVENT:
March 18, 1978 SYSTEM INVOLVED:
Makeup and High Pressure Injection COMPONENT INVOLVED:
Pumps CAUSE:
Malfunction of time delay relay.
,SrQUENCE OF INTEREST:
Small LOGA ACTUAL OCCURRENCE:
Relay failure.
REACTOR NAME:
Three Mile Island 1 DOCKET NUMBER:
50-289 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
819 MWe REACTOR AGE:
3.8 yr VENDOR:
B&W ARCHITECT-ENGINEERS:
Gilbert Associates, Inc.
OPERATORS:
Metropolitan Edison LOCATION:
10 milea BE of Harrisburg, PA DURATION:
360(a) hours PLANT OPERATING CONDITION:
0% power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; (9made inoperable; (d)________
DISCOVERY METHOD:
During test.
COMME~NT:
Lost 2 of 3 makeup/high pressure injection pumps because of faulty timers.
These two pumps are normally those started by an SFAS signal.