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 1
Unavailabilities are in units of per demand D- . Failure rates are in units of per hour HR-1 .
Makeup pumps MU-PIA, MU-PIC Power restored MU-11IA start MU-PIC start Potential MU-PIA, MU-PIC tripped to MU-PIA, ' nd run and run Severe running and voltage MU-PIC buses Core on buses for MU-PIA, Damage MU-PIC interrupted for testing during refueling
______________ No Yes
_____________ No to I1 No I No No - N~oLOCA & 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 Potential Sequence LOCA* Trip Feedwater and Pressure Recirculation Severe No.
Secondary Injection and LPR/HPI Core Heat Removal. Cross-Connect Damage No 2
3 4
-I 5 C7%
6 7
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.