05000424/LER-2002-002
| Vogtle Electric Generating Plant - Unit 1 | |
| Event date: | |
|---|---|
| Report date: | |
| 4242002002R00 - NRC Website | |
FACILITY NAME (1)
DOCKET
05000-424 LER NUMBER (6)
A. REQUIREMENT FOR REPORT
This event is reportable per 10 CFR 50.73 (a)(2)(i) because the unit operated in a condition prohibited by the Technical Specifications (TS) when TS required action was not complied with for an inoperable containment isolation valve (CIV).
B. UNIT STATUS AT TIME OF EVENT
At the time of the discovery of this event on April 5, 2002, Unit 1 was in a refueling outage in Mode 5 (Cold Shutdown) at 0 percent of rated thermal power. Other than that described herein, there was no inoperable equipment that contributed to the occurrence of this event.
C. DESCRIPTION OF EVENT
On April 5, 2002, personnel were performing thermal overload bypass testing per procedure 28905-C, "18-Month Motor-Operated Valve Thermal Overload Bypass Test, Train B." An orange thermal overload bypass jumper was found disconnected in MCC cubicle 1BBE-07. The affiliated load for this circuit is the Reactor Coolant System Hot Leg Sample Valve, 1HV-3548, which is also a containment isolation valve (CIV). The jumper was promptly re-connected.
Without the jumper in place, an overcurrent condition may have tripped the valve's (1HV-3548) thermal overload, rendering it incapable of performing its containment isolation function of closing. Technical Requirements Manual, Section 13.8.2, requires that a motor-operated valve with an inoperable thermal overload bypass jumper be declared inoperable and the appropriate TS condition be entered. Because 1HV-3548 is a CIV, TS 3.6.3, "Containment Isolation Valves," is applicable. Since steps had not been taken to comply with action statement requirements, the unit operated in a condition prohibited by the TS.
D. CAUSE OF EVENT
The cause of this event was the failure to properly install and verify the bypass jumper. Work order documentation shows that the jumper had been re-installed and verified during the previous refueling outage in October 2000. Because there had been no other work in the MCC since that time, it is assumed that the jumper was not properly installed in 2000. The wire location is believed to have contributed to these personnel errors by the licensee electricians involved. The wire visually appeared to be landed, but when pulled, it was found to not be connected.
FACILITY NAME (1)
DOCKET
05000-424 LER NUMBER (6)
E. ANALYSIS OF EVENT
Valve 1HV-3548 has not failed to perform its intended safety function as a result of this condition. Additionally, testing has provided high confidence that operation of the subject valve's actuator motor would not have resulted in an thermal overload condition; therefore, the valve would have performed its intended function upon receipt of a containment isolation signal. In the unlikely event that the actuator motor were to trip when the valve was called on to perform its containment isolation function, operators would ensure closure of the other CIV for this penetration. Therefore, there has been no adverse effect on the safety of the plant or on the health and safety of the public as a result of this event.
This event does not represent a safety system functional failure.
F. CORRECTIVE ACTIONS
1) The disconnected jumper was relanded and the valve was returned to service.
2) Personnel involved with this event will be counseled regarding the need for diligence when installing and verifying safety-related wiring.
3) Prior to the Unit 2 fall refueling outage, this event will be added to operating experience training for electricians.
G. ADDITIONAL INFORMATION
1) Failed Components:
None 2) Previous Similar Events:
This LER addressed an historical wiring error in a different system. Because its cause was indeterminate, it is unknown if there are similarities in the causes.
3) Energy Industry Identification System Code:
Nuclear Sampling System — IP Containment Isolation System - JM