ENS 42711
ENS Event | |
|---|---|
20:47 Jul 17, 2006 | |
| Title | Control Room Ventilation Flow Below Limits |
| Event Description | During review of instrumentation calibration, it was determined that a faulty flow instrument was used for determination of CREFS (Control Room Emergency Filtration System) flow. Due to the error of the flow instrumentation previous test results were deemed to be high outside acceptance criteria. These tests were performed in October of 2005. The CREFS was declared inoperable and preparation was made to rerun the surveillance. At 1900 the surveillance was completed. The results of the surveillance determined that CREFS flow was below the allowable limit. The minimum flow for CREFS is a requirement for post DBA dose calculation for Control Room personnel. With minimum flow not maintained, the Control Room post accident dose calculations may be violated.
CREFS remains inoperable pending adjustments of ventilation dampers and successful performance of surveillance testing. Resident inspector has been notified. The licensee has entered Technical Specification LCO 3.7.4, Condition A, which is a 7 day LCO.
The licensee is retracting this report based on the following: This notification is being made to retract Event Notification#42711 which reported a loss of safety function due to the unplanned inoperability of the Control Room Emergency Filtration System (CREFS). CREFS was declared inoperable due to flow below the acceptance criteria required per surveillance testing. Upon further evaluation, CNS has determined that CREFS satisfies the Technical Specifications (TS) surveillance requirements and that the safety function was not lost. The surveillance procedure acceptance criteria for CREFS minimum flow is not required by the TS and is not a direct indicator of system operability. The procedure has been revised to remove the minimum flow acceptance criteria. It has been determined that CREFS, at the flow conditions documented on July 17, 2006 and during a past surveillance in 2005, satisfied TS and USAR requirements and was capable of performing its safety function. The licensee will inform the NRC Resident Inspector. Notified R4DO (Farnholtz). |
| Where | |
|---|---|
Cooper  Nebraska (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:+0.85 h0.0354 days <br />0.00506 weeks <br />0.00116 months <br />) | |
| Opened: | Andrew Ohrablo 21:38 Jul 17, 2006 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Jul 27, 2006 |
| 42711 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |