05000341/LER-2013-002
| Fermi 2 | |
| Event date: | 08-30-2013 |
|---|---|
| Report date: | 10-22-2013 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3412013002R00 - NRC Website | |
Initial Plant Conditions:
Mode 1 Reactor Power 68 percent
Description of the Event
On August 30, 2013 at approximately 0017 hours1.967593e-4 days <br />0.00472 hours <br />2.810847e-5 weeks <br />6.4685e-6 months <br />, while performing a routine surveillance procedure, Instrumentation and Control (I&C) technicians discovered that a thermocouple lead was not properly terminated to its associated terminal block knife switch. The thermocouple red lead was terminated to point TT-4 inside Relay Room panel H11P614, instead of point TT-3. The thermocouple blue lead was properly terminated to point TT-4. Since both red and blue leads were landed on the same terminal point, a new "thermocouple junction" was created in panel HI 1P614. This resulted in the temperature switch fed by this thermocouple monitoring the Relay Room H11P614 panel temperature instead of the intended Reactor Core Isolation Cooling (RCIC) [BN] area room temperature. The temperature switch involved, E51N602A, provides the Division I isolation [JM.] of the RCIC steam piping when steam leakage [U] is determined to be present as indicated by a high RCIC Area room temperature. It is required to be operational by plant Technical Specification (TS) 3.3.6.1.
Investigation revealed that the improper wiring occurred on August 16, 2013 at 1357 hours0.0157 days <br />0.377 hours <br />0.00224 weeks <br />5.163385e-4 months <br /> when Temperature Switch E5111602A was taken out of service for replacement of its damaged terminal block knife switches. At the time of the replacement, the temperature in the Relay Room was approximately the same as the temperature in the RCIC Room. The two I&C Technicians working the job thought they had positive indication that the equipment was terminated and operating properly since the temperature sensed was as expected. It was subsequently determined that the technicians involved in the switch replacement had failed to properly implement the concurrent verification process when the equipment was returned to service.
For an inoperable steam leak detection input, TS 3.3.6.1 requires the affected channel to be placed in the tripped condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or isolation of the affected penetration within one additional hour. Thus the approximately 14 days that the steam leak detection was inoperable without isolation of the RCIC steam line exceeded the allowed out of service time for E51N602A.
Significant Safety Consequences and Implications The equipment in question is expected to trip the ROC Turbine if temperatures in the RCIC Room exceed their limits. The equipment is required to isolate the ROC Turbine in the event of a steam leak. However, the function was not lost due to redundant instrumentation that would have provided the isolation function. A large break in the RCIC steam line would have also resulted in a steam line isolation due to high steam line flow trip logic which was unaffected by this event.
This event did not present a significant radiological risk. A condition did not exist that required the equipment to perform its function. If conditions had existed requiring the equipment to perform its function, the other train of steam leak detection would have provided the required isolation function. Should the other train have failed, the RCIC Turbine would not have been shut down and steam would not have been isolated which had the potential to allow additional steam to be released to the RCIC Room. The area radiation monitoring system was available to alert Operations of increasing radiation in the RCIC room. Additionally, process radiation monitors were available to automatically isolate the reactor building ventilation system [VA] and start the Standby Gas Treatment System [BH] which filters reactor building ventilation prior to release to the environment.
This event is being reported under 10 CFR 50.73(a)(2)(i)(B), as an event or condition that resulted in the operation or condition which was prohibited by the Technical Specifications. Since the inoperability of the E51N602A was not known at the time it was made inoperable, the Technical Specifications action requirement to isolate the RCIC Steam Line was not followed.
Cause of the Event
The direct cause for the event was that workers installed thermocouple leads for instrument E51N602A incorrectly when replacing its terminal block knife switches on August 16, 2013. Insufficient rigor was applied by the I&C Technicians during installation and verification activities for interim alterations of electrical circuitry for the RCIC System. This resulted in a failure to effectively implement the concurrent verification process intended to prevent termination errors.
Corrective Actions
The panel wiring was corrected, the associated Channel Functional Test was satisfactorily completed at 0145 hours0.00168 days <br />0.0403 hours <br />2.397487e-4 weeks <br />5.51725e-5 months <br /> on August 30, 2013 and the equipment was returned to service. The qualifications of the I&C Technicians involved were removed until such time as the individuals were re-trained. Re- training on Verification Practices was conducted with I&C Group personnel.
This event has been entered into the Fermi 2 Corrective Actions Program.
Additional Information
A. Failed Component:
N one B. Previous Licensee Event Reports (LERs) on Similar Problems:
There are no other LERs on similar problems noted within the past five years.