ENS 41224: Difference between revisions
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| event date = 11/24/2004 12:20 MST | | event date = 11/24/2004 12:20 MST | ||
| last update date = 12/14/2004 | | last update date = 12/14/2004 | ||
| title = Eccs Loops Declared Inoperable | | title = Eccs Loops Declared Inoperable in Support of Log Term Accident Mitigation | ||
| event text = The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. | | event text = The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. | ||
On November 24, 2004, at approximately 12:20 Mountain Standard Time (MST), Palo Verde Nuclear Generating Station Unit 3 was operating at 0% power at approximately normal operating temperature and pressure when 3 of the 4 ECCS injection check valves were identified to be in a degraded condition. While performing normal torque verifications on the bonnet bolts for these check valves, it was identified that the graphoil seals were degraded in that the seal material had extruded past the retaining ring. Although there was no evidence of actual leakage associated with these valves, the long term integrity of the valves during post accident operation could not be assured. As a result, the Operators conservatively declared both trains of ECCS inoperable per LCO 3.5.3 and 3 of 4 Safety Injection Tanks inoperable per LCO 3.5.1, requiring entry into LCO 3.0.3. Operations also declared both RCS loops inoperable per LCO 3.4.5. A cooldown and depressurization of the RCS is in progress to Mode 5. | On November 24, 2004, at approximately 12:20 Mountain Standard Time (MST), Palo Verde Nuclear Generating Station Unit 3 was operating at 0% power at approximately normal operating temperature and pressure when 3 of the 4 ECCS injection check valves were identified to be in a degraded condition. While performing normal torque verifications on the bonnet bolts for these check valves, it was identified that the graphoil seals were degraded in that the seal material had extruded past the retaining ring. Although there was no evidence of actual leakage associated with these valves, the long term integrity of the valves during post accident operation could not be assured. As a result, the Operators conservatively declared both trains of ECCS inoperable per LCO 3.5.3 and 3 of 4 Safety Injection Tanks inoperable per LCO 3.5.1, requiring entry into LCO 3.0.3. Operations also declared both RCS loops inoperable per LCO 3.4.5. A cooldown and depressurization of the RCS is in progress to Mode 5. | ||
Latest revision as of 21:22, 1 March 2018
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+0.68 h0.0283 days <br />0.00405 weeks <br />9.31464e-4 months <br />) | |
| Opened: | David Oakes 20:01 Nov 24, 2004 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Dec 14, 2004 |
| 41224 - NRC Website
| |
Palo Verde with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |