05000306/FIN-2008002-02
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Finding | |
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| Title | Concerns Regarding Testing of Check valve SI-9-5 |
| Description | One unresolved item was identified due to concerns regarding the past operability of Safety Injection Check Valve SI-9-5. During surveillance testing on March 16, 2008, Safety Injection Check Valve SI-9-5 did not seat. The failure of the check valve to properly seat resulted in bypass flow greater than the 3 gallons per minute allowed by the TS. The licensee initiated CAP 01131266 to document the surveillance test failure. When open, Check Valve SI-9-5 provided a flow path for low head safety injection and long-term low head recirculation. This valve prevented over-pressurization of the residual heat removal system when in the closed position. Flow testing of the check valve was performed in accordance with an operational surveillance procedure. This procedure required the installation of a jumper connected between two drain valves. Operations personnel manipulated the valves to create a drain path on the low pressure side of the check valve. The flow through this drain path was measured and then compared against the TS requirements. Initial surveillance testing resulted in a flow measurement that exceeded the TS requirements. Licensee individuals proceeded to re-test the check valve seven additional times. Each time the measured flow rate exceeded the TS requirements. After the seventh test failure, the licensee stopped the testing and developed a trouble shooting plan, which included raising reactor pressure above the pressure band specified in the test procedure and hitting the valve with a hammer. The licensee developed the plan based on the assumption that the check valve was unable to pass the surveillance test due to the inability to establish enough differential pressure across the valve to ensure the valve was closed. Once approved, licensee personnel implemented the troubleshooting plan by raising reactor pressure, opening the drain path, tapping on the valve with a 1 pound hammer, and monitoring leakage for a few minutes. After tapping on the valve, leakage decreased to within the surveillance and TS requirements. Operations personnel then lowered reactor pressure within the pressure band specified in the surveillance procedure. Licensee personnel observed that the check valve leakage remained within the specified requirements. Following these actions, the licensee re-performed the surveillance test and documented that there was zero leakage past the check valve. Operations personnel then concluded that the valve was operable based on the test methodology implemented and results achieved. The inspectors reviewed SI-9-5s maintenance history. The inspectors determined that the licensee had trouble getting SI-9-5 to pass the same surveillance test discussed above during the 2006 Unit 1 refueling outage. The licensee documented this in CAP 01033504. After several additional surveillance test attempts, the licensee again tapped on the valve body with a hammer to get the valve to seat. Following this action, SI-9-5 passed the surveillance test. Corrective actions for CAP 01033504 included developing an improved test procedure to resolve the previous test difficulties; however this task was not completed. The licensee also added a task to open and inspect SI-9-5 during the February 2008 Unit 1 refueling. The inspectors discussed this action with licensee personnel and determined that the licensee had originally planned to open and inspect Check Valve SI-9-5 during the February 2008 Unit 1 refueling outage. However, the licensee subsequently eliminated the check valve inspection from the outage scope to improve resource utilization and reduce overall outage duration. Following the check valve testing, the NRC monitored the licensees re-start activities. During this time the NRC expressed several concerns to licensee management relating to the testing of Check Valve SI-9-5. These concerns included: Potential preconditioning due to increasing reactor pressure and tapping on the valve prior to the valve passing the surveillance test. The NRC believed that the licensees actions were preconditioning because increasing reactor pressure and hitting the valve with a hammer were not actions that were considered to be permanent maintenance. In addition, these actions failed to provide reasonable assurance that the check valve would remain closed if the valve was disturbed or the differential pressure conditions changed during the next operating cycle; Use of a hammer on safety-related equipment was unacceptable; Failure to implement corrective actions to resolve previous testing difficulties following the 2006 Unit 1 refueling outage; Removal of the valve inspection from the outage scope; The failure to recognize the need for an operability determination once the inspectors concerns were known; Technical inadequacies in the licensees subsequent operability determination; and The need to implement additional compensatory measures/corrective actions to ensure that SI-9-5 was re-tested if the valve was disturbed or the differential pressure conditions changed during the next operating cycle. At the conclusion of the inspection period, the licensee had initiated three CAPs to document the information discussed above (01132288, 01131266, and 01033504). Based upon the information known to date, it appears that several weaknesses in licensee performance contributed to the difficulties experienced when testing SI-9-5. The licensee was continuing to evaluate the inspectors concerns and provide plant specific probabilistic risk assessment and historical testing information to the NRC at the conclusion of the inspection period. As a result, the inspectors were unable to fully evaluate this issue for potential performance deficiencies and safety significance. This issue will be tracked as an unresolved item (URI) pending the receipt and review of the probabilistic risk assessment and testing information discussed above. (URI 05000282/2008002-02 |
| Site: | Prairie Island  |
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| Report | IR 05000306/2008002 Section 1R22 |
| Date counted | Mar 31, 2008 (2008Q1) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.22 |
| Inspectors (proximate) | P Laflamme C Zoia S Ray J Jacobson M Phalen K Stoedter D Jones L Haeg P Zurawski R Skokowskid Szwarck Stoedter L Haeg M Phalen P Zurawski R Skokowski D Mcneil |
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Finding - Prairie Island - IR 05000306/2008002 | ||||||||||||||||||||||||||||||||||
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Finding List (Prairie Island) @ 2008Q1
Self-Identified List (Prairie Island)
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