05000282/FIN-2008003-01
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Finding | |
|---|---|
| Title | 11 TURBINE-DRIVEN Auxiliary Feedwater Pump Inoperable During Startup from Outage 1R25 |
| Description | On March 23, 2008, the licensee tested the auxiliary feedwater system using Surveillance Procedure (SP) 1103, 11 Turbine-Driven Auxiliary Feedwater Pump Once Every Refueling Shutdown Flow Test. During the test, the 11 TDAFW pump was secured due to the turbine outboard bearing temperature reaching 220 degrees Fahrenheit (oF). Operations personnel declared the 11 TDAFW pump inoperable. The licensee conducted troubleshooting efforts and determined that the high bearing temperature was due to improper installation of the turbine insulation following maintenance. The licensee properly re-installed the insulation and the pump was restored to an operable status on March 24, 2008. The inspectors reviewed the Unit 1 operator logs and the results of multiple auxiliary feedwater system tests conducted between March 16 and March 23, 2008, to determine whether the licensee had a prior opportunity to identify the outboard bearing temperature issue. This review included an assessment of turbine outboard bearing temperature trends captured by the Emergency Response Computer System (ERCS) system. The inspectors ascertained that on March 16, 2008, operations personnel performed the following tests concurrently: SP 1102 11 Turbine-Driven Auxiliary Feedwater Pump Monthly Test; SP 1330 11 Turbine-Driven Auxiliary Feedwater Turbine/Pump Bearing Temperature Test; and SP 1376 Auxiliary Feedwater Flow Path Verification Test After Each Cold Shutdown. Operations personnel began the series of tests by performing SP 1102. This test was performed with the 11 TDAFW pump operating and supplying approximately 35 gpm of water to the steam generators. Once this condition was established, the operators transitioned into SP 1376 which required that the 11 TDAFW pump supply 70 gpm of water to the steam generators for approximately 20 minutes. The inspectors performed a detailed review of the turbine outboard bearing temperature data provided by ERCS and identified that the bearing temperature reached approximately 216oF and was continuing to increase when the 20 minutes had elapsed. Operations personnel considered the results of SP 1376 satisfactory even though the bearing temperature was within 4 degrees of the vendor specified limit. Operations personnel then reduced the 11 TDAFW pump flow rate to establish the conditions needed to perform SP 1330. The reduction in feedwater pump flow resulted in a corresponding reduction in bearing temperature. The inspectors reviewed SP 1330 and found that the procedure could be considered satisfactory when three successive turbine outboard bearing temperature readings taken ten minutes apart varied by less than 3 degrees. The inspectors reviewed the ERCS data attached to SP 1330 and found that the operators concluded that the 11 TDAFW pump outboard bearing temperature was stabilized at 211oF. The inspectors questioned this conclusion because the outboard bearing temperature recorded during SP 1376 was approximately 5 degrees higher. The operators also initiated CAP 1131305 to document that the outboard bearing temperature exceeded the alert limit of 203oF. However, no further actions were taken to address or evaluate whether the 11 TDAFW pump outboard bearing temperature would remain less than 220oF during post-accident conditions. The inspectors sampled the licensees corrective action system to determine whether any previous bearing issues had occurred due to the improper installation of insulation following maintenance. The inspectors found that the 11 TDAFW pump outboard turbine bearing failed during the performance of SP 1103 on June 6, 2006. The licensee determined that the bearing failed due to improper bearing installation during maintenance. However, improper insulation installation following maintenance contributed to the increased bearing temperatures. Corrective actions for this event consisted of replacing the bearing, installing the insulation correctly, and providing additional oversight of maintenance activities conducted on the 22 TDAFW pump in 2007. The inspectors questioned engineering and maintenance personnel to determine if written procedural guidance regarding the installation of the turbine insulation following maintenance had been provided to the insulators. The inspectors were informed that written procedural guidance had not been provided because insulation installation was considered to be a skill of the craft activity. At the conclusion of the inspection period, based upon the information known to date, the inspectors have not concluded whether the high temperatures experienced by the 11 TDAFW bearings caused the pump to be inoperable. As a result, the inspectors were unable to fully evaluate this issue for potential performance deficiencies and safety significance. Therefore, this issue was considered an unresolved item (URI 05000282/2008003-01) pending further review by the inspectors. The inspectors needed to evaluate how the operability of the 11 TDAFW was impacted by: (1) opportunities for the licensee to have identified the high bearing temperatures during the testing completed March 16 though 23, 2008, and (2) the timeliness and adequacy of corrective actions taken for past issues related to the improper installation of the TDAFW insulation following maintenance, specifically, whether or not the insulation installation was skill of the craft |
| Site: | Prairie Island  |
|---|---|
| Report | IR 05000282/2008003 Section 1R15 |
| Date counted | Jun 30, 2008 (2008Q2) |
| Type: | URI: |
| cornerstone | Other |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | C Zoia E Dickson K Stoedter L Kozak M Munir M Phalen P Zurawski R Skokowski S Thomasd Szwarck Stoedter L Haeg M Phalen P Zurawski R Skokowski D Mcneil |
| INPO aspect | |
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Finding - Prairie Island - IR 05000282/2008003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Prairie Island) @ 2008Q2
Self-Identified List (Prairie Island)
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