05000265/LER-2005-001
| Docket Numbersequential Revmonth Day Year Year Month Day Year N/Anumber No. 05000 | |
| Event date: | 05-25-2005 |
|---|---|
| Report date: | 10-21-2005 |
| 2652005001R00 - NRC Website | |
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) (If more space is required, use additional copies of NRC Form 366A)(17)
PLANT AND SYSTEM IDENTIFICATION
General Electric - Boiling Water Reactor, 2957 Megawatts Thermal Rated Core Power Energy Industry Identification System (ElIS) codes are identified in the text as [XX] .
EVENT IDENTIFICATION
Core Spray Discharge Pressure Switch Out of Calibration Due to Apparent Manufacturing Defect
A. CONDITION PRIOR TO EVENT
� Unit: 2 Event Date: May 25, 2005�Event Time: 0040 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> � Reactor Mode: 1 Mode Name: Power Operation Power Level: 095%
B. DESCRIPTION OF EVENT
At 0040 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> (CDT) on May 25, 2005, during calibration of a discharge pressure switch on the Unit 2 Core Spray System [BM], the Pressure Switch [PS] was found to be outside the Technical Specification (TS) allowed range. The switch was recalibrated to within the TS allowed range. At 1640 hours0.019 days <br />0.456 hours <br />0.00271 weeks <br />6.2402e-4 months <br /> on May 26, 2005, after review by Engineering, the pressure switch was declared inoperable due to inconsistent operation and TS 3.3.5.1, Condition G, allowing operation with the inoperable switch for eight days, was entered. The switch was removed, a replacement switch was installed and calibrated, the pressure switch was declared operable and the TS condition was exited at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> on May 27, 2005.
This pressure switch had originally been installed on February 18, 2005, and had exhibited one inconsistency involving the reset value prior to being discovered out of calibration on May 25, 2005. This switch provides a permissive signal to the Auto Blowdown System indicating that the Core Spray pump is operating.
The removed switch was analyzed at Exelon PowerLabs. The conclusion was that the inconsistent operation was due to the switch actuating arm being able to pivot between its stop tabs due to the bend angle of the arm. PowerLabs noted that the failure appeared to be associated with an as-built condition.
On September 15, 2005, it was determined that this condition constituted operation prohibited by TS, and was reportable under 10CFR50.72(a)(2)(i)(B).
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) (If more space is required, use additional copies of NRC Form 366A)(17)
C. CAUSE OF EVENT
The inconsistent operation of the pressure switch was caused by the switch actuating arm being able to pivot between its stop tabs due to the bend angle of the arm. Due to the short time that the switch was installed in the plant when it failed and the fact that the other three switches on Unit 2 and the four switches on Unit 1 have not exhibited this failure, this condition is most likely a manufacturing defect.
D. SAFETY ANALYSIS
The safety significance of this event was minimal. The other three switches on Unit 2 were operable and would have provided the permissive.
E. CORRECTIVE ACTIONS
Process controls have been put in place to ensure new switches are inspected prior to installation.
The spare switch currently in the storeroom and the switch installed on Unit 2 on May 27, 2005, were inspected to ensure they do not have this manufacturing defect.
F. PREVIOUS OCCURRENCES
A review of LERs for the last three years did not identify any failures of Mercoid pressure switches at Quad Cities Nuclear Power Station.
G. COMPONENT FAILURE DATA
The pressure switch was a type DA-7043-804-21E pressure switch manufactured by Mercoid.