05000285/LER-2007-005
| Docket Numbersequential Revmonth Day Year Year Month Day Yearnumber No. 05000 | |
| Event date: | 09-12-2007 |
|---|---|
| Report date: | 12-17-2007 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2852007005R00 - NRC Website | |
BACKGROUND
The Fort Calhoun Station (FCS) Technical Specification (TS) requirements for surveillance testing reads, in part:
3.0.4� Surveillance Requirements shall be met during the MODES or other specified conditions in the individual Limiting Conditions for Operation, unless otherwise stated in the Surveillance Requirement. Failure to meet a Surveillance, whether such failure is experienced during the performance of the Surveillance or between performances of the Surveillance, shall be failure to meet the OPERABILITY requirements for the corresponding Limiting Condition for Operation. Failure to perform a Surveillance Requirement within the allowed surveillance interval, defined by Specifications 3.0.1 and 3.0.2, shall constitute noncompliance with the OPERABILITY requirements for the corresponding Limiting Condition for Operation except as provided in Specification 3.0.5. The time limits of the ACTION requirements are applicable at the time it is identified that a Surveillance Requirement has not been performed. Surveillance Requirements do not have to be performed on inoperable equipment.
3.0.5� If it is discovered that a Surveillance was not performed within its specified surveillance interval, then compliance with the requirement to declare the OPERABILITY requirements for the Limiting Condition for Operation not met may be delayed, from the time of discovery, up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or up to the limit of the specified surveillance interval, whichever is greater. This delay period is permitted to allow performance of the Surveillance. A risk evaluation shall be performed for any Surveillance delayed greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and the risk impact shall be managed.
If the Surveillance is not performed within the delay period, the OPERABILITY requirements for the Limiting Condition for Operation must immediately be declared not met, and the applicable ACTION(S) must be entered.
When the Surveillance is performed within the delay period and the Surveillance is not met, the OPERABILITY requirements for the Limiting Condition for Operation must immediately be declared not met, and the applicable ACTION(S) must be entered.
EVENT DESCRIPTION
On September 12, 2007, it was discovered that the testing frequency for raw water (RW) pump AC-10D should have been increased in response to the results of testing on July 11, 2007. The date for complying with the increased frequency plus 25 percent (September 6, 2007) had passed when the condition was discovered. TS 3.0.4 requires equipment to be declared inoperable when a surveillance requirement has not been met, except as provided in TS 3.0.5. This TS provides alternatives to immediately declaring inoperability, but has a 24-hour time limit during which actions are required. Contrary to TS 3.0.5, a risk assessment was not performed nor was the surveillance test performed as required. The actions required by TS 3.0.5 were not taken.
Pump AC-10D had previously been tested on July 11, 2007. At that time, purrip performance was evaluated using information in Technical Data Book (TDB) III.34, Revision 25, "AC-10D Pump Curve." Based on the pump curve in TDB 111.34, Revision 25, the test results were within the 'Acceptable Range.' On September 12, 2007, it was determined that TDB 111.34 had not been appropriately updated before the July 11, 2007 test was evaluated. The test results were evaluated using an out-dated pump curve. When the July test results were re-evaluated using the updated pump curve, it was determined that pump performance was within the 'Alert Range.' Test results in the 'Alert Range' require testing frequency to be doubled until the cause of performance in the 'Alert Range' has been determined and corrected.
The requirement to increase the test frequency for AC-10D was identified and documented in a condition report (CR) (2007-3734) on September 12, 2007. The CR indicated that an increase in test frequency was required. The CR did not specifically state the date plus 25 percent (i.e., September 6, 2007) by which testing would have been required to comply with the increased test frequency. This deadline was not effectively conveyed to the shift manager (SM). As such, the operability determination concluded that AC-10D was operable based on the July 11, 2007 test results.
However, per TS 3.0.4, compliance with operability requirements had expired on September 6, 2007. On September 12, 2007, when the requirement for increased testing frequency was identified, TS 3.0.5 became applicable, but was not applied. The applicability of TS 3.0.5 was not recognized until September 14, 2007. Later that day (September 14, 2007), when AC-10D was tested, pump performance was found to be in the 'Required Action Range' and the pump was declared inoperable as required pending further evaluation.
Evaluation of the test results on September 14, 2007, (CR 2007-3772) determined that the pump had experienced normal wear, and pump performance had remained above the 'Minimum Operability' curve, indicating that it was able to perform its safety-related functions.
CR 2007-3768, written on September 14, 2007, states that " During a pre-job brief for the performance of OP-ST RW-3031, it was revealed that the drop date for OP-ST-RW-3031 as defined by a reduced surveillance test interval would have been September 6th, 2007." The title of surveillance test OP-ST-RW-3031 is "AC-10D Raw Water Pump Quarterly Inservice Test." This CR indicates that the time of discovery to perform the surveillance was September 14, 2007, 0900, which was the time of the pre-job briefing described in the condition description. OP-ST-RW-3031 was subsequently performed on September 14, 2007.
Contrary to the statement in CR 2007-3768, as documented in CR 2007-3783, the time of discovery should actually have been September 12, 2007 at approximately 1100 when the system engineer (SE) discussed the requirement for increased surveillance frequency with the SM. This discussion should have started the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> clock as defined in TS 3.0.5. CR 2007-4196 was written to document this issue. The reportability of the situation was not recognized until October 18, 2007, when it was determined that TS 3.0.5 had been violated. This event is reportable per 10 CFR 50.73(a)(2)(i)(B).
CONCLUSION / ROOT CAUSE
When the diminished performance of AC-10D was identified, implications of the associated requirement to increase surveillance frequency were not promptly recognized and addressed. Upon discovery that the performance of AC 10D on July 11, 2007, warranted increased surveillance frequency, compliance with the reduced surveillance interval became an operability issue. Since the deadline for compliance with the reduced interval had passed, the pump was not in compliance with its surveillance requirements, and could not properly be considered operable at that point except as provided by TS 3.0.5. Without application of TS 3.0.5, AC-10D did not have an adequate basis for operability. The root cause analysis identified that the station's operability determination process was not effectively implemented.
CORRECTIVE ACTIONS
The surveillance tests on the RW pumps were completed and corrective action taken as described above. RW pump AC-10D was determined to have been able to perform its required safety function at all times during this event.
Procedures documenting the RW pump curves have been updated as appropriate.
The RW pump quarterly tests have been revised to require the system engineer to verify that the correct pump curve is used before the test is performed.
Until the completion of the more comprehensive training listed below station management will provide a briefing to operations and engineering personnel on this event and operability determinations as they pertain to missed surveillance tests. These briefings will be completed by December 31, 2007.
The following corrective actions are being completed to address the root case of this event:
1. Initial and continuing training of appropriate system and program engineering personnel is required to enhance system and program engineering's understanding on the surveillance test compliance requirements for a component in the 'Alert' or 'Required Action Range.' 2. Training of appropriate operations personnel is required to enhance understanding on the surveillance test compliance requirements for a component in the 'Alert' or 'Required Action Range.' Actions 1 and 2 above will be completed by April 17, 2007.
Additional actions will be addressed by the corrective action system.
SAFETY SIGNIFICANCE
When AC-10D was tested on July 11, 2007, performance had been in the 'Alert Range' as defined in OP-ST-RW-3031. This indicated that performance had declined as compared to the baseline performance that had been determined when the pump was tested on April 20, 2007. When the pump was tested on September 14, 2007, performance was in the 'Required Action Range.' In accordance with American Society of Mechanical Engineers (ASME) Code and in-service testing (IST) program requirements, the pump was declared inoperable pending evaluation and/or corrective action. As stated in NUREG-1482 "Guidelines for Inservice Testing at Nuclear Power Plants," Rev. 1, 2004, "The reference values for the pump and the Code-specified action limits may be much higher than the necessary capacity of the pump since the Code limits are not based on system requirements." In the case of AC-10D, although pump performance was below the Code-specified 'Required Action Range' curve, performance remained above the 'Minimum Operability' curve. When the performance was evaluated, it was determined that the decline in performance had been due to normal wear, and the pump had remained capable of performing its safety related functions. (Pump lift was subsequently adjusted, and testing was performed to establish a new baseline performance curve. The pump was then returned to service.) Since the pump remained capable of performing its safety-related functions, there was no effect on the health and safety of the public.
SAFETY SYSTEM FUNCTIONAL FAILURE
This event does not result in a safety system functional failure in accordance with NEI-99-02.
PREVIOUS SIMILAR EVENTS
CR 200601176 and CR 200601186 document discovery that out-dated component cooling water pump curves were used to evaluate testing of AC-3C performed on December 20, 2005. When the December 20, 2005, data was plotted on the updated pump curve the test results were found to be in the 'Acceptable Range.' The condition was discovered on March 21, 2006, during preparations to test the pump.