05000425/LER-2003-001
| Docket Number(S) | |
| Event date: | 0-5-2003 |
|---|---|
| Report date: | 06-29-2004 |
| 4252003001R01 - NRC Website | |
FACILITY NAME (1) DOCKET LER NUMBER (6 PAGE (3)
A. REQUIREMENT FOR REPORT
This report is required per 10 CFR 50.73 (a)(2)(i)(B). The performance of a Technical Specification (TS) surveillance was missed and, although the NRC has utilized their discretion in agreeing not to exercise enforcement of the TS requirements for this event, it represented operation of the unit in a condition prohibited by the TS.
B. UNIT STATUS AT TIME OF EVENT
At the time of this event, Unit 2 was in Mode 1 (Power Operations) at 100% 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 October 26, 2003, personnel were performing TS surveillances on the Solid State Protection System (SSPS). A switch in the test circuit that is used to test memories logic functions would not operate properly in all positions. This prevented successful completion of the surveillance testing for the following functions:
1. Memory test for feedwater isolation 2. Actuation logic test for feedwater isolation on safety injection or P-14 permissive 3. Permissive P-10 block of source range trip The surveillance absolute late date was November 5, 2003. After this time, and following expiration of a 24-hour TS Required Action Completion Time, a unit shutdown would have been required to be initiated per the action requirements of TS 3.3.1, 3.3.2 and 3.0.3. A telephone conversation with NRC personnel was conducted on November 4, 2003. During this conversation, the NRC granted a notice of enforcement discretion (NOED) to allow the TS surveillance requirement to be late without enforcement for a period 28 days. The 28 days represented a reasonable period of time for a written request, to change the TS, to be processed by the NRC. The TS change allowed the required surveillance testing to be delayed until after the end of the fuel cycle in Spring 2004, or until the next unit shutdown to Mode 5 (Cold Shutdown), whichever comes first. On December 3, 2003, the requested TS change was approved.
FACILITY NAME (1) DOCKET LER NUMBER (6 PAGE (3) �1
D. CAUSE OF EVENT
The memories logic test switch was replaced during the Spring 2004 refueling outage. During follow-up testing, it was found that a reset pushbutton in the same circuit was experiencing intermittent failure due to wear and tear and this failure was the cause of the event.
E. ANALYSIS OF EVENT
The switch involved is part of the test circuit only, and has no effect on the operation of the SSPS.
There were four options to address this issue. The first was to replace the faulty switch during power operation. This would have involved taking Train B SSPS out of service for at least 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, thus incurring an increase in risk while one train of SSPS is out of service plus the attendant trip risk while working on the SSPS while at power. This alternative was ruled out because of the additional time required beyond the current 24-hour Completion Time to restore a train of SSPS logic and the trip risk. The second option was to shut the unit down to Mode 5 to replace the faulty switch. This would have involved an increase in risk associated with shutting the unit down, plus an additional thermal cycle on the reactor coolant pressure boundary. A third alternative was to complete the required testing using jumpers to mimic the operation of the suspected faulty switch. This would have involved entering the logic cabinet during power operation and installing jumpers which posed a potential trip risk as well as the potential for error. The fourth alternative was to remain at power until the refueling outage scheduled for April 2004. The very small increase in risk associated with this alternative was offset by compensatory actions, and there was no net increase in risk to the health and safety of the public. The compensatory actions included briefing control room operators on the circuits in the Train B SSPS that have not been tested due to the failure of this switch, directing them as to appropriate actions to take in the event of a failure of one of these untested circuits, and increasing operator surveillances of plant parameters indicative of precursors that could challenge the untested functions.
During the 2R10 outage, the pushbutton switch was replaced. Subsequently, the deferred surveillance testing was completed satisfactorily. The basis for deferral of the surveillances was validated by the fact that there were no failures of components during the surveillances after replacement of the defective pushbutton.
Based on these considerations, there is no adverse effect on plant safety or on the health and safety of the public as a result of this condition.
The event does not represent a safety system functional failure.
FACILITY NAME (1) DOCKET LER NUMBER (6 PAGE (3)
F. CORRECTIVE ACTION
1)The memories logic test switch was replaced during the Spring 2004 refueling outage.
2) An investigation into the cause of the memories logic test switch failure determined that a reset pushbutton had experienced intermittent failure due to wear and tear. Similar SSPS pushbutton switches will be replaced during the upcoming refueling outage in each unit.
3) The required Technical Specification surveillance was completed prior to Mode 4 during the 2R10 refueling outage.
G. ADDITIONAL INFORMATION
1) Failed Component:
Memories Reset pushbutton switch manufactured by Grayhill, Inc.
Part number 7-26B.
1) Previous Similar Events:
None 3) Energy Industry Identification System Code:
Solid State Protection System — JG Main Feedwater System — SJ Safety Injection System — BQ Nuclear Instrumentation System - JD