05000352/LER-2006-002
| Docket Numbersequential Revmonth Day Year Year Month Day Yearnumber No. 05000 | |
| Event date: | 03-19-2006 |
|---|---|
| Report date: | 05-18-2006 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3522006002R00 - NRC Website | |
Unit Conditions Prior to the Event Unit 1 was in Operational Condition (OPCON) 5 (Refueling Mode) in 1R11 Outage on March 19, 2006. There were no structures, systems or components out of service that contributed to this event.
Description of the Event
During the performance of ST-4041-470-11 "Cyclic Test Of Main Steam Safety Relief Valve Solenoid And Air OperatorAssemblies" on March � 2006 in-outagelft11;the red/open bulbs-for the PSV--4t=1F013C-, PSV-41— 1F013A and PSV-41-1F013N SRVs failed when the SRV solenoids were de-energized. The red/open lights come on when the handswitches for the valves are taken to OPEN. When the handswitches were taken back to CLOSE, the red bulbs became very bright for a short period of time before they went out. On subsequent operations of the handswitches/solenoids, the red indications did not function. Troubleshooting revealed that the red/open bulbs were burned out. This same condition occurred for the C, A, and N SRVs (all of the SRVs controlled at the Remote Shutdown Panel [EIIS:JL]). This is the first time that the SRV solenoids have been operated using the handswitches at the RSP for surveillance testing. The testing was enhanced resulting in a change of methodology from contact resistance to valve manipulation.
A review of C61-1050-E-010, Elementary Diagram for Remote Shutdown System, was performed. When the handswitches for the SRVs (S38, S39, and S40) are taken from OPEN to CLOSE, the red bulb remains in the circuit with the solenoid. When the energy of the solenoid's magnetic field collapses upon de-energization, the resulting "kickback" is forced entirely into the red light bulb, which becomes very bright before it burns out.
The open indication works on the first opening of the RSP SRVs. If the SRVs are closed and re-opened, there will not be any open indication until the bulbs are replaced. This condition does not occur when the SRVs are operated from the Main Control Room (MCR).
This event resulted in a review that indicated that the plant likely operated in a condition that was prohibited by Technical Specifications since initial startup. This condition was prohibited by Technical Specifications (TS) 3.3.7.4 when at power Modes 1 arid 2. The valve position indication of Tech Spec Table 3.3.7.4-1 for the SRVs was-inoperable.liowever,-the oparatpr has' alternate -means to determine the status-of the-SRVs. Therefore-this LER is being submitted pursuant'to the requirements of 10CFR50.73(a)(2)(i)(B).
Analysis of the Event
There were no actual safety consequences associated with this event. The potential safety consequences of this event were minimal since the three SRVs would have operated as required although there would not have been proper open indication.
There was no adverse impact and very low safety significance since no transient requiring the remote shutdown panel occurred during the outage. The valve open indication would have burned out if operated from the RSP.
Cause of the Event
The event was caused by a faulty design for the SRV control circuit at the remote shutdown panel.
The extent of condition is limited to Unit 1. Field Deviation Disposition Request (FDDR) HH24733 added a Metal Oxide Varister (MOV) to the Unit 2 wiring during construction.
Corrective Action Completed Anlvt0V was added to_the.Uniti _circuit similartawhat_was_done_for_Unit 2 and the SRVs were tested satisfactorily.
Previous Similar Occurrences There were no previous similar occurrences where the SRV lights failed to relight following operation from the Remote Shutdown Panel.
Component data:
Cause: B (Design, Manufacturing, Construction/Installation) System: JL Panels System Component: HS Switch Hand Manufacturer: G080 General Electric Model: N/A Reportable to EPIX: Yes