ML20168A441
| ML20168A441 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1975-013-00 | |
| Download: ML20168A441 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
103002 Date:
April 29, 1975
Title:
Multiple Valve Failures and RCIC Inop erable at Brunswick 2 The failure sequence was:
- 1. The reactor was operating at 10% power and RCIC was inoperable.
- 2. The "B" safety valve stuck open.
(reason unspecified)
- 3. The operator failed to scram the reactor as specified by emergency procedures.
- 4. HFCI manually initiated but was shutdown due to high level in the torus.
(This was done to prevent torus water from entering the core following expected HPCI suction switchover to torus on high torus level.
- 5. ~Reactor autoscram as MSIV's were manually closed to conserve reactor water.
- 6. An attempt was made to place the "B" RHR loop in service to cool the torus during the relief valve blowdown, however this failed.
The service water supply valve to the RHR heat exchanger failed to open.
Corrective action:
All relief valves except the ':A" relief valves were removed, overhauled., and reinstalled.
The "A" valve 'had just been overhauled and was operating correctly.
Design purpose of failed system or component:
- 2. RHR provides for long term core cooling.
- 3. The relief valves provide for a controlled depressurization of the reactor.
Unavailability of system per WASH 1400:
RCIC:
8 x 10- 2 D Unavailability of componeni per WASH 1400:
- RHR valve (SOy):
1, 10- 3/D relief valve, failure to close:
1 x~ 10-21D Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1
Reactor operating Operator realizes Operator fails HPCI manually Operator closes at 10% power and the "B" safety to manually initiated, but MSIV's which RCIC unavailable valve is stuck open scram the reactor shutdown due initiates scram Potential Severe Core Damage No No -
eventual trip, on low water level, HPCI initiation and MSIV closure on low-low water level NO4 No A 0 NSIC 103002 -
Actual Occurrence of Multiple Valve Failures and ROIC Inoperable at Brunswick 2
SV inadver Reactor RCIC/HPCI Automatic LPCI or Long Potential sti Icks ope4 Adequate System Operates Adequate Core Core III Cooling Damage No Yes No Yes Yes Yes Yes Sequence No.
2 3
5 6
NSIC 103002 -
Sequence of Interest for Multiple Valve Failures and RCIC Inoperable at Brunswick 2 I The operator failed to manually scram the reactor as emergency instruction requires.
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER: 103002 DATE OF LER:
May 16, 1975 DATE OF EVENT:
April 29, 1975 SYSTEM INVOLVED:
RCIC, RHR, Reactor coolant system (RCS)
COMPONENT INVOLVED:
isolation & relief valves CAUSE:
mechanical failure of the valve pilot, operator error SEQUENCE OF INTEREST:
loss of feedwater flow ACTUAL OCCURRENCE-. multiple valve failures and RCIC inoperable at Brunswick 2 REACTOR NAME:
Brunswick 2 DOCKET NUMBER:
50-324 REACTOR TYPE:
BWR DESIGN ELECTRICAL RATING:
821 MWe REACTOR AGE:
.1 yr VENDOR:
GE ARCHITECT-ENGINEERS:
United Engineers & Constructors OPERATORS.
Carolina Power & Light LOCATION:
3 miles N of Southport, NC DURATION:
N/A PLANT OPERATING CONDITION:
10% power SAFETY FEATURE TYPE OF FAILURE: CDinadequate performance; (b) failed to start; (c) made inoperable; (d)____________
DISCOVERY METHOD:
Operational event COMMENT:
I