05000296/LER-2002-001
| Ill | |
| Event date: | 01-09-2002 |
|---|---|
| Report date: | 03-08-2002 |
| 2962002001R00 - NRC Website | |
FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3) Browns Ferry Nuclear Plant, Unit 3 05000296 2002 � -- � 001 � -- � 00
I. PLANT CONDITION(S)
At the time of the event, Unit 3 was in Mode 1 at 100 percent reactor power, approximately 3458 megawatts was shutdown and defueled.
II. DESCRIPTION OF EVENT
A. Event:
On January 9, 2002, at 0421 hours0.00487 days <br />0.117 hours <br />6.960979e-4 weeks <br />1.601905e-4 months <br /> CST, maintenance personnel (other utility, non-licensed) commenced surveillance 3-SR-3.3.6.1.3(3D), High Pressure Coolant Injection (HPCI) [BJ] Steam Line Space High Temperature Calibration. This surveillance involved replacement of primary containment isolation instrumentation [JM] temperature switches [TS] with shop-calibrated switches, then returning the removed switches to the shop to obtain as-found calibration data.
At 0849 hours0.00983 days <br />0.236 hours <br />0.0014 weeks <br />3.230445e-4 months <br />, the maintenance personnel removed the primary containment isolation temperature switches for the Reactor Core Isolation Cooling (RCIC) system [BN] and replaced them with the temperature switches intended for the HPCI system. The switches for the RCIC system are the same type switches and located in close proximity to the HPCI switches. However, the actuation temperature for the HPCI switches is 170 degrees F increasing instead of the 147 degrees F increasing required for the RCIC system. Similar component identifiers are used which differ only by the system number (e.g. 3-TS-071- 0002N (RCIC) and 3-TS-073-0002N (HPCI)).
While preparing to obtain the as-found calibration data, it was discovered that the RCIC steam line space temperature switches had been replaced instead of the HPCI switches as intended.
At 1425 hours0.0165 days <br />0.396 hours <br />0.00236 weeks <br />5.422125e-4 months <br />, maintenance personnel notified control room operators that the incorrect temperature switches had been replaced. Operators initiated technical specification action for inoperable primary containment isolation instrumentation; within one hour, isolate the affected penetration flow path(s).
At 1509 hours0.0175 days <br />0.419 hours <br />0.0025 weeks <br />5.741745e-4 months <br />, operators completed the technical specification required action to isolate the RCIC steam supply line by closing valve 3-FCV-71-3 [FCV]. RCIC was declared inoperable and Technical Specification LCO 3.5.3.A.2 was entered.
At 1818 hours0.021 days <br />0.505 hours <br />0.00301 weeks <br />6.91749e-4 months <br />, after replacement of the RCIC temperature switches, Operations personnel exited LCO 3.3.6.1.F.1.
At 1840 hours0.0213 days <br />0.511 hours <br />0.00304 weeks <br />7.0012e-4 months <br />, after returning RCIC to service, Operations personnel exited Technical Specification LCO 3.5.3.A.2.
Because the Primary Containment Isolation Instrumentation was inoperable for a period longer than that allowed by Technical Specifications, this event is reportable in accordance with 10 CFR 50.73(a) (2) (i) (B), as any operation or condition prohibited by plant's Technical Specifications.
B. Inoperable Structures, Components, or Systems that Contributed to the Event:
None FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3) Browns Ferry Nuclear Plant, Unit 3 05000296 2002 -- 001 -- 00 C. Dates and Approximate Times of Major Occurrences:
January 9, 2002, at 0421 hours0.00487 days <br />0.117 hours <br />6.960979e-4 weeks <br />1.601905e-4 months <br /> CST Maintenance personnel began performance of surveillance 3-SR-3.3.6.1.3(3D), HPCI Steam Line Space High Temperature Calibration.
January 9, 2002, at 0849 hours0.00983 days <br />0.236 hours <br />0.0014 weeks <br />3.230445e-4 months <br /> CST Maintenance personnel incorrectly replaced temperature switches for the RCIC steam line space high temperature instead of for the HPCI system as required by the surveillance.
January 9, 2002, at 1425 hours0.0165 days <br />0.396 hours <br />0.00236 weeks <br />5.422125e-4 months <br /> CST Maintenance personnel notified Operations personnel of incorrect temperature switch replacement.
Operations personnel initiated technical specification LCO action 3.3.6.1.F.1 to manually isolate the RCIC steam line.
January 9, 2002, at 1509 hours0.0175 days <br />0.419 hours <br />0.0025 weeks <br />5.741745e-4 months <br /> CST Operations personnel completed the technical specification LCO action. RCIC system was declared inoperable and Technical Specification LCO 3.5.3.A.2 was entered.
January 9, 2002, at 1818 hours0.021 days <br />0.505 hours <br />0.00301 weeks <br />6.91749e-4 months <br /> CST Operations personnel exited Technical Specification LCO action 3.3.6.1.F.1 after satisfactory replacement of the RCIC temperature switches.
January 9, 2002, at 1840 hours0.0213 days <br />0.511 hours <br />0.00304 weeks <br />7.0012e-4 months <br /> CST Operations personnel declared RCIC system operable and exited Technical Specification LCO 3.5.3.A.2.
D. Other Systems or Secondary Functions Affected
None
E. Method of Discovery
While preparing to perform the as-found portion of the calibration surveillance, it was determined that the incorrect switches were replaced. Control room operators were notified of the error at 1425 hours0.0165 days <br />0.396 hours <br />0.00236 weeks <br />5.422125e-4 months <br />.
F. Operator Actions
Upon notification of the error, Operations personnel initiated technical specification LCO action 3.3.6.1.F.1, manually isolate the RCIC steam line. The RCIC system was declared inoperable and Technical Specification LCO 3.5.3.A.2 was entered.
G. Safety System Responses
None FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3) Browns Ferry Nuclear Plant, Unit 3 05000296 2002 � -- � 001 � -- � 00 III. � CAUSE OF THE EVENT
A. Immediate Cause
Maintenance personnel removed the temperature switches for the RCIC system instead of the HPCI switche8 as required by 3-SR-3.3.6.1.3(3D).
B. Root Cause
The root cause of this event was personnel error. The Maintenance personnel involved failed to properly execute the verification process in accordance with approved site procedures. The personnel focused on the "address" portion of the unique identification number (UNID) rather than the complete UNID.
C. Contributing Factors
HPCI and RCIC switches are of the same type and located in close proximity to each other. The UNIDs for the HPCI and RCIC temperature switches are identical with the exception of the system identification number. (e.g. 3-TS-071-0002N (RCIC) and 3-TS-073-0002N (HPCI)) IV. � ANALYSIS OF THE EVENT Surveillance Requirement 3-SR-3.3.6.1.3(3D), High Pressure Coolant Injection Steam Line Space High Temperature Calibration, requires the HPCI steam line space temperature switches 3-TS-073-0002N, -0002P, -0002R, and -0002S to be replaced with calibrated switches. Procedure steps for removal and replacement of the temperature switches require first and second party verification. Procedure SPP-10.3, "Verification Program" requires the second-party verifier to ensure that the actual component identification matches the identification of the component required to be verified. The maintenance personnel did not properly implement error prevention techniques such as self-checking. The verifications focused on only the address portion of the UNID instead of the entire UNID. This resulted in the incorrect switches being replaced.
This was the first time that these particular individuals had performed this task. The planned access route to the area was not accessible and another route was used. This resulted in the individuals becoming disoriented with respect to the correct work location. The similarity and proximity of the HPCI and RCIC switches and the similarities in their UNIDs led the individuals to believe that they were at the correct location.
When commencing the portion of the surveillance to obtain the as-found data for the removed switches, it was discovered that the incorrect switches had been replaced. Operations was notified of the error and initiated the required Technical Specification actions.
V. � ASSESSMENT OF SAFETY CONSEQUENCES The function of RCIC steam space temperature switches 3-TS-071-0002N, -0002P, -0002R, and -0002S is to monitor for postulated breaks in the piping supplying motive steam to the RCIC system turbine. The Browns Ferry Updated Final Safety Analysis Report Section 7.3.4.7 states:
High temperature in the vicinity of the RCIC equipment could indicate a break in the RCIC steam line. The automatic closure of certain Group A valves prevents the excessive loss of reactor coolant and the release of significant amounts of radioactive material from the nuclear system process barrier. When high temperature occurs near the RCIC equipment, the RCIC FACILITY NAME (1) DOCKET LER NUMBER 16) PAGE (3) Browns Ferry Nuclear Plant, Unit 3 05000296 2002 � - � 001 � -- � 00 turbine steam line is isolated. The high above anticipated normal RCIC system enough to provide timely detection of an In this case the "Group A" valves referenced are close upon detection of a possible leak from the Through the installation of additional supports, particularly rugged. The piping stresses seen therefore by these temperature switches are very low.
Upon confirmation that the incorrect switches had accordance with the technical specification required original error. The correct switches were reinstalled original error.
The RCIC temperature switches which were removed increasing, whereas the HPCI temperature switches actuation setpoint of 170 degrees F increasing.
the isolation of the RCIC steam line upon a postulated occurred at a higher temperature. This could have pressure boundary into secondary containment The following factors are seen to reduce the risk 1. The BFN design basis has demonstrated that the areas monitored by these temperature 2. The incorrect switches were in place for only action (7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />) 3. During this short interval, the isolation function a higher isolation temperature 4. The BFN risk-informed in-service inspection RCIC system piping (water and steam) breaks Based on the above discussion, the safety effects V. � CORRECTIVE ACTIONS
A. Immediate Corrective Actions
temperature isolation operational levels RCIC turbine steam the RCIC steam RCIC steam line the RCIC steam line by the RCIC been replaced, LCO action.
and demonstrated had a nominal which were The installed switches RCIC steam resulted in a prior to isolation.
impacts of this the RCIC steam switches, making a short period of would have occurred (RI-ISI) program to be only 0.02% of this event are functionally setting was selected far enough to avoid spurious operation, but low line break.
line isolation valves, which are signaled to piping.
piping in the torus area has been made steam line piping in the areas monitored the RCIC steam line was isolated in This was completed within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> of the to be operable within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> of the actuation setpoint of 147 degrees F installed in their place had a nominal were functional in this location, though line pipe break in the area would have greater loss of steam from the reactor event:
piping is exposed to very low stresses in the likelihood of a pipe break very small time prior to taking the appropriate LCO for a postulated pipe break, though at estimated the total risk contribution of all of the BFN total CDF.
considered to be negligible.
test, and return to service the RCIC personnel.
and Controls (I&C) Maintenance personnel following those methods.
personnel.
Initiated and implemented work order to replace, temperature switches.
B. Corrective Actions to Prevent Recurrence
Administered appropriate personnel corrective actions to involved Conducted stand-down briefings on each shift with Instrument to stress the proper verification methods and importance of Refresher verification training was administered to l&C Maintenance FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE 13) Browns Ferry Nuclear Plant, Unit 3 05000296 VI. � ADDITIONAL INFORMATION
A. Failed Components
functional failure in accordance with NEI 99-02.
None B. Previous LERs on Similar Events None
C. Additional Information
None D. Safety System Functional Failure:
This event did not result in a safety system VII. � COMMITMENTS None