ENS 41084
ENS Event | |
|---|---|
17:00 Oct 2, 2004 | |
| Title | Plant Declared the Emergency Recirculation Ventilation System Inoperable. |
| Event Description | A surveillance test was being performed on the Emergency Recirc vent System and all six dampers on both trains failed to stroke in the required Tech. Spec. times. Therefore, both trains of the Emergency Recirc Vent System were declared inoperable and the plant entered T.S. 3.0.3. The LCO action statement requires the plant to be in mode 2 in 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> and mode 3 in the following six hours and mode 4 in the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. They are currently troubleshooting the problem.
The NRC resident Inspector was notified HOO Note: see event 41085
Update to [Event] Notifications 41084 and 41085: At 1840 [EDT] on 10/02/04 it was determined that the apparent slow response times of the Control Room Emergency Recirculation [CRER] dampers was due to a malfunctioning relay in the initiation circuit, not due to failure of the dampers. The LCO actions associated with the CRER system were exited and the actions associated with the initiation instrument were entered. Therefore the plant is no longer required to shutdown per T.S. 3.0.3. The plant shutdown has been terminated. Plant power will be returned to 100%. The licensee has notified the NRC resident Inspector. Notified R3DO (Thomas Kozak).
At 1300 on 10/02/04, results of a surveillance indicated that dampers in both trains of the Control Room Emergency Recirculation System (CRERS) were slower than allowed by Technical Specifications (TS) requiring both trains of the CRERS to be declared inoperable. With both trains inoperable, Technical Specification 3.0.3 was entered which required a plant shutdown. The shutdown was commenced at 1500. This condition was reported as required in Event Notification 41085. Additionally, with both CRERS trains inoperable, this condition was determined to be reportable as a loss of safety function (accident mitigation) and was reported as required in Event Notification 41084. Subsequently, it was determined that the failure was the result of a defective time delay relay in the radiation monitor initiation circuit. Other inputs that would have caused the dampers to reposition in an accident were not impacted. The appropriate TS (3.3.7.1), for the radiation monitor, was entered and TS 3.0.3 was exited. The significant actions required by this TS were to restore the function within 7 days or place the system in emergency recirculation. It did not require entry into an action to shutdown. When this condition was identified, TS 3.0.3 was exited, the shutdown was terminated, and the plant was restored to full power. Since a TS required shutdown was not required, Event Notification 41085 is being retracted. The condition was also reported as a loss of safety function for the accident mitigation function of CRERS. The CRERS is automatically activated by a Loss of Coolant Accident (LOCA) signal or a Control Room Ventilation (CRV) high radiation signal. The LOCA instrumentation circuitry was not affected by the defective time delay relay and thus the damper stroke times were not impacted. The CRV airborne radiation monitor signal is considered a "diverse" signal to the LOCA signal. Since the LOCA signal would have properly initiated the CRERS and the CRV high radiation signal is redundant, there was no loss of safety function. Since there was no loss of safety function, Event Notification 41084 is being retracted. The licensee has notified the NRC Resident Inspector. NRC R3DO(Gardner) has been notified. |
| Where | |
|---|---|
Perry  Ohio (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-1.63 h-0.0679 days <br />-0.0097 weeks <br />-0.00223 months <br />) | |
| Opened: | Robert Kidder 15:22 Oct 2, 2004 |
| NRC Officer: | Chauncey Gould |
| Last Updated: | Oct 25, 2004 |
| 41084 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |