05000285/LER-2009-004
| Telephone Number (Include Area Code) | |
| Event date: | 11-26-2006 |
|---|---|
| Report date: | 04-23-2010 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2852009004R01 - NRC Website | |
BACKGROUND
Containment integrity is defined in the Fort Calhoun Station (FCS) Technical Specifications (TS) as:
(1) All non-automatic containment isolation valves which are not required to be open during accident conditions and blind flanges, except for valves that are open under administrative control as permitted by Specification 2.6(1)a, are closed.
(2) The equipment hatch is properly closed and sealed.
(3) The personnel air lock satisfies Specification 2.6(1)b.
(4) All automatic containment isolation valves are operable, locked closed, or deactivated and secured in their closed position (or isolated by locked closed valves or blind flanges as permitted by a limiting condition for operation).
(5) The uncontrolled containment leakage satisfies Specification3.5, and (6) The sealing mechanism associated with each penetration (e.g., welds, bellows or 0-rings) is operable.
TS section 2.6(1)a, states "Containment integrity shall not be violated unless the reactor is in a cold or refueling shutdown condition. Without containment integrity, it must be restored within one hour or the plant must be in at least hot shutdown within the next six hours, or be subcritical and less than 300 degrees F within the next six hours and in cold shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. Normally locked or sealed-closed valves (except for PCV 742A/B/C/D) may be opened intermittently under administrative control without constituting a violation of containment integrity.
EVENT DESCRIPTION
Containment integrity was unknowingly violated on October 26, 2003, and November 26, 2006. This was a result of opening manual containment isolation valve SI-410 (Safety injection Tanks Fill/Drain Valve) when containment integrity was required and administrative controls (dedicated operator) were not implemented.
Prior to November 2009, a step existed in QC-ST-SI-3006, "Safety Injection Leakoff Piping Forty Month Functional Test," to open manual containment isolation valve SI- 410, as well as re-aligning other valves, in preparation for performing a leak check of the safety injection tanks leakoff piping. The procedure prerequisites require the reactor coolant system be pressurized above 600 psig, which results in the reactor coolant system being greater than 210 deg F and containment integrity being required. Prior to the ST being performed on November 1, 2009, it was recognized by a shift manager that the opening of SI-410 needed to be administratively controlled in order to be in compliance with TS 2.6(1)a.
On November 1, 2009, a revision was made to QC-ST-SI-3006. A note, a caution, and a step were added at the beginning of the procedure section to require that a dedicated operator be assigned to close manual containment isolation valve SI-410 (Safety injection Tanks Fill/Drain Valve) when directed by the control room, to establish containment integrity.
Nuclear Safety Review Group (NSRG) and System Engineering (SE) personnel performed a review of past performances of QC-ST-SI-3006. The review determined that the station unknowingly entered and subsequently violated TS 2.6(1)a on October 26, 2003 and November 26, 2006 as a result of opening valve SI-410 when containment integrity was required and administrative controls (dedicated operator) were not implemented.
This issue was identified and documented in Condition Report (CR) 2009-6365.
CONCLUSION
The cause of this event is failure of the reviewer of the test procedure to identify and resolve the conflict between required test conditions (i.e., RCS temperature greater than 210 deg F and containment integrity required) and opening SI-410 (i. e., manual containment isolation valve).
CORRECTIVE ACTIONS
Procedure QC-ST-SI-3006 was revised to require that administrative controls be in place prior to opening containment isolation valve SI-410. Additional actions will be administered by the corrective action system.
SAFETY SIGNIFICANCE
There was no impact to safety in ways previously not evaluated in the USAR. Since the plant was in mode 3, the opening of SI-410 without administrative control constituted a violation of containment integrity per TS 2.6(1)a.
However, SI-410 being open did not provide a leak pathway from containment to external atmosphere. Pressure boundary was maintained during the test since valves HCV-2983 and SI-185 were closed for the portion of the piping that was outside of containment. HCV-2983 and SI-185 are a normally closed automatic valve and normally locked closed manual valve, respectively. For the performances of QC-ST-SI-3006 during the 2003 and 2006 refueling outages (RFOs), control room log data indicate that SI-185 and HCV-2983 were both closed during performances of the test. Therefore, the containment integrity violation was entirely administrative and nuclear safety was not compromised.
SAFETY SYSTEM FUNCTIONAL FAILURE
This event does not result in a safety system functional failure in accordance with NEI-99-02.
PREVIOUS SIMILAR EVENTS
�NRC FORM 366A (9-2007) PRINTED ON RECYCLED PAPER