ML20168A727

Final ASP Analysis - Robinson (LER 261-77-029)

ML20168A727
Person / Time
Site:	Robinson
Issue date:	06/16/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1977-029-00
Download: ML20168A727 (4)

Text

PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:

135079 Date:

December 8, 1977

Title:

All Safety Injection Pumps Inoperable During Heatup at Robinson 2 The failure sequence was:

1. While the reactor was shut down, the SI pumps were tested and determined to be operable...

The pump breakers were then racked out as required for over-pressure protection during cold shutdown.

2. During heatup ("'4 hrs later) the pump breakers were not racked in, as required before going above 200*F due to a misunderstanding of the procedures.

3. This fact was discovered while completing a minimum equipment list and the breakers were racked in (five hours after they were required to be racked in).

Corrective action;

1. The breakers were racked in.

2. operating procedures were revised as necessary to require the pumps to be in service before exceeding 2000F.

Design purpose of failed system or component:

1. The safety injection pumps provide high pressure injection of borated water in the event of a small LOCA.

Unavailability of system per WASH 1400:

• High Pressure Injection System:

1.2 x 10-2 /D Unavailability of component per WASH 1400:

• human error of omission:

3 x 10-3 /1)

Unavailabilities are in units of per demand D-1.

Failure rates are in units of per hour R-1.

Breakers on safety Primary heatup Check-off list Operator failed SI pump injection pumps from cold initialed that to recognize breakers racked-out for shutdown (RCS SI pumps were control room SI racked-in overpressure pro-temp >2000 F) operable due to pump indicating and SI dueduiong shutdrown-misunderstanding lights notPU S

duedrn htonof "operable" illuminated operable I

Potential Severe Core Damage No No -

no LOCA No No -

no LOCA No No NSIC 135079 -

Actual Occurrence for Inoperable Safety Injection Pumps at Robinson 2

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 Sequence No.

2 3

4 5

6 7

NSIC 135079 -

Sequence of Interest for Inoperable Safety Injection Pumps at Robinson 2

CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:

135079 DATE OF LER:

December 8, 1977 DATE OF EVENT:

November 23, 1977 SYSTEIM INVOLVED:

Safety injectiom COMPONENT INVOLVED:

Pumps, breakers CAUSE:

Breakers incorrectly racked out, human error SEQUENCE OF INTEREST Small LOCA ACTUAL OCCURRENCE:

Misunderstanding of procedures during a heatup, the. pump breakers were not racked in prior to exceeding 200'F.

REACTOR NAME: Robinson 2 DOCKET NUMBER:

50-261 REACTOR TYPE:

PWR DESIGN ELECTRICAL RATING:,

700 MWe REACTOR AGE:

.3 yr VENDOR

Westinghouse ARCHITECT-ENGINEERS:

Ebasco OPERATORS:

Carolina Power & Light Co.

LOCATION:

5 -ni-6s NW of Hiartsville, SC DURATION:

5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> PLANT OPERATING CONDITION:

Hot shutdown SAFETY FEATURE TYPE OF FAILURE:

(a) inadequate performance; (b) failed to start;

<0made inoperable; (d) _______

DISCOVERY METHOD:

While completing a minimum equipment list COMMENT:

The fact that the pumps were not in service was indicatedhby a lack of pump status lights on the control board.

The operators did not notice that the lights were out.