05000397/LER-2010-001
| Docket Numbersequential Revmonth Day Year Year Month Day Yearnumber No. 05000 | |
| Event date: | 06-30-2010 |
|---|---|
| Report date: | 08-30-2010 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3972010001R00 - NRC Website | |
Event Description
On June 30, 2010, diagnostic testing of FDR-V-219 [WK] was completed and a condition prohibited by LCO 3.6.4.2, Conditions A and C, was discovered. Results of the testing showed that the valve close stroke was approximately 1 inch from being fully closed and seated. This valve is an SCIV and must be capable of closing and staying closed to be considered operable. Upon discovery of the inoperable status, the TS required actions for this condition were completed by closing FDR-V-220 and isolating the flow path. Subsequently, the actuator was replaced, the valve stroke was adjusted, and the valve was declared operable.
The discrepant condition occurred on July 4, 1994 when the valve actuator was replaced. The work instructions directed that the valve packing be tightened to hold the valve disk in place without verifying that the valve was closed and seated. The valve actuator was installed and the valve stroke was set with the valve disk unseated and partially open. Subsequently, the position limit switches were set based on the incorrect stroke length. This did not allow indication of the problem to be observed by control room operators. Routine maintenance also failed to identify this condition. The required two-year visual verification and the quarterly surveillance on FDR-V-219 do not provide positive verification of the valve's ability to stop flow.
Immediate Corrective Actions
Upon discovery, the affected penetration flow path was isolated by closing FDR-V-220 (the valve in series with FDR-V-219), and a once per 31 day action was established to verify isolation of the affected penetration flow path. This met the TS 3.6.4.2 (Condition A) required actions for an inoperable SCIV. FDR-V-220 was verified closed through AOV diagnostic testing.
Causes The direct cause of the valve not being able to fully close automatically was due to incorrectly setting the actuator. The root cause of the event was inadequate work instructions to verify that the valve was fully closed and seated prior to setting the actuator stroke.
Further Corrective Actions On July 9, 2010, AOV diagnostic testing was performed after the repair of FDR-V-219, to ensure that the valve was fully closing. Additional corrective actions to address contributing causes, extent of cause, and recurrence prevention include: (1) improved testing using AOV diagnostics, (2) procedure revisions to the post maintenance testing process, and (3) preventative maintenance clarifications.
26158 R4 NRC FORM 366A� U.S. NUCLEAR REGULATORY COMMISSION (9-2007)
CONTINUATION SHEET
Assessment of Safety Consequences
A review was conducted of work orders concerning FDR-V-219 and FDR-V-220 during the time period when FDR-V-219 was discrepant. This review concluded that FDR-V-220 was either closed and deactivated or operable. Consequently, the affected penetration flow path was either isolated or capable of being isolated. Therefore, this event did not involve an event or condition that alone could have prevented the fulfillment of any safety function described in 10 CFR 50.73(a)(2)(v).
Similar Events No similar events have been reported by Columbia Generating Station.
Energy Industry Identification System (EIIS) Information BIS codes are bracketed [1where applicable in the narrative.
26158 R4