ML20168A714
| ML20168A714 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1974-LTR | |
| Download: ML20168A714 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
90421 Date:
April 17, 1974
Title:
Auxiliary Feed Pump Suction Strainers Clogged at Point Beach I The failure sequence was:
- 1. With Unit 1 in a cooldown, the "A" motor-driven AFW pump did not-*provide adequate flow.
- 2. An in-line suction strainer, of which the operators were unaware, was found to be 95% plugged.
- 3. A similar strainer, similarly plugged, was found in the suction line of the "B" motor-driven AFW pump.
- 4. A partially plugged strainer was found in the suction lines of both units turbine-driven pumps.
Corrective action;
- 1. All the strainers were removed.
- 2. Other piping systems were examined-to determine if other unidentified strainers existed.
Design purpose of failed system or component:
- 1. The auxiliary feedwater pumps provide water to the steam generators for reactor cooling in the event the main feedwater system is not operable.
Unavailability of system per WASH 140G:
- auxiliary feedwater:
2.5 X 10-4 (start + 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />)
Unavailability of component per WASH 1400:
- strainers, not included 1-pumps, failure to run:
3 X1
/hr.
kUnava ilabilitie~ are in units of per demand D-1.
Failure rates are in units of per hour HR-T.
Unit 1 in cooldowTI Motor-driven AFW Motor-driven AFW Turbine-driven AFW Unit 2 status pump A fails to PUMP B suction pump suction unknown deliver adequate strainer clogged strainer partially flow to Unit 1 clogged (applicable due to clogged to both unit turbine-suction strainer driven pumps)
Potential Severe Core Damage No -
offsite power for main feed pumps available No No No NSIC 90421 -
Actual Occurrence for Auxiliary Feed Pump Suction Strainers Clogged at Point Beach 1 & 2
Potential Severe Core Damage Sequence No.
Nn 1
No Yes 2
3 Yes 4
No 5
4.
- I~A No Yes 6
7 I14 (.')
,Yes 8
No 9
No Yes 10 11
~(F)
Yes 12 Yes 13 NSIC 90421 -
Sequence of Interest for Auxiliary Feed Pump Suction Strainers Clogged at Point Beach I & 2
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUIMBER:
90421 DATE OF LER:
April 17, 1974 DATE OF EVENT:
April 7, 1974 SYSTEM INVOLVED:
Auxiliary feedwater COMPONENT INVOLVED:
AFW pump strainers CAUSE:
Strainers plugged SEQUENCE OF INTEREST:
Loss of feedwater ACTUAL OCCURRENCE:
Inoperable AFW pumps during plant cooldown.
REACTOR NAME:
Point Beach 1 DOCKET NUMBER:
50-266 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
497 MWe REACTOR AGE:
3.5 yr VENDOR:
Westinghouse ARCHITECT-ENGINEERS:
Bechtel OPERATORS:
Wisconsin Electric Power Co.
LOCATION:.15 miles northiof Manitowoc, Wisc.
DURATION:
360(a) hours PLANlT OPERATING CONDITION:
Unit 1 in cooldown SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b,) failed to start; (2)made inoperable; (d)__________
DISCOVERY METHOD:
during operation
- COMMENT, The affected AFW pumps provide auxiliary feedwater for both units.
Monthly tests failed to reveal strainers because test was run at shutoff head -
the only flow was through a I" ID bypass line & this low flow masked the plugged strainer.