ENS 45103
ENS Event | |
|---|---|
03:06 May 29, 2009 | |
| Title | Control Room Emergency Filtration System Excessive Leakage |
| Event Description | On 28 May 2009 the Control Room Emergency Filtration System (CREFS) was declared inoperable due to a degraded Control Room Envelope (CRE). Two CRE boundary doors were found with excessive leakage. Based on the identified leakage, reasonable assurance that CREFS would fulfill its safety function could not be established.
The CRE boundary doors support CREFS at CNS. CREFS is a single train system and per 10CFR50.72(b)(3)(v)(D) an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> report is required due to the fact that at the time of discovery this condition could have prevented the fulfillment of the safety function of an SSC [system, structure or component] that is required to mitigate the consequences of an accident. Actions to implement mitigating actions have been initiated in accordance with plant Technical Specifications. The NRC Senior Resident Inspector has been notified of the condition.
The licensee is retracting this report based on the following: This notification is being made to retract Event Notification EN 45103 which reported a loss of safety function due to the unplanned inoperability of the Control Room Emergency Filtration (CREF) system. The CREF system was declared inoperable on May 28, 2009, due to a degraded Control Room Envelope (CRE). Two CRE boundary doors were found with excessive leakage and reasonable assurance that the CREF system would fulfill its safety function could not be established at that time. Cooper Nuclear Station (CNS) has subsequently determined through further testing that while the CREF system was procedurally required to be declared inoperable, the ability of the CREF system to perform its safety function was not lost. CREF system safety function is to maintain the habitability of the CRE following a loss of coolant accident or fuel handling accident involving handling lately irradiated fuel. CNS performed testing on June 5, 2009. CRE adjacent building pressures were raised to create harsh conditions and one CRE door was cracked open to simulate a boundary leaking at about four times the CRE leakage of May 28, 2009. Testing results showed the CRE remained considerably more positive, in comparison to previous tracer gas testing performed in July 2004, and it is not credible the CRE unfiltered in-leakage exceeded maximum allowable limits. Thus, CNS determined the CREF system was still capable of performing its safety function during the timeframe when the two CRE boundary doors were identified leaking excessively. The NRC Resident Inspector was notified of this retraction. Notified R4DO (Geoffrey Miller) |
| 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:+0.52 h0.0217 days <br />0.0031 weeks <br />7.12296e-4 months <br />) | |
| Opened: | Steve Wheeler 03:37 May 29, 2009 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jun 11, 2009 |
| 45103 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |