ENS 50149
ENS Event | |
|---|---|
13:42 May 25, 2014 | |
| Title | Control Room Ventilation Boundary Door Inoperable |
| Event Description | At 0942 on May 25, 2014, the Cook Nuclear Plant (CNP) declared both Control Room Emergency Ventilation trains inoperable in accordance with LCO 3.7.10 due to an inoperable Control Room Envelope when a control room boundary door was identified as not latching correctly during a security door check. The latch would not have been able to maintain the door closed during an event resulting in Control Room Pressurization. At this time, Security established a continuous door post and would have been able to maintain the door closed.
At 1602 on May 25, 2014, repairs to the control room boundary door latch were completed restoring the Control Room Envelope to Operable. The licensee has notified the NRC Senior Resident Inspector. This notification should have been made within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of the event in accordance with 10 CFR 50.72 (b)(3)(v)(D) per guidance in section 3.2.7 of NUREG-1022 - Event or Condition that Could Have Prevented Fulfilment of a Safety Function, but was not recognized at that time.
The purpose of this report is to retract EN#50149 (May 25, 2014). On June 19, 2014, Cook Nuclear Plant concluded that the EN could be retracted based on the completion of a Maintenance Rule Evaluation (MRE) performed by Systems Engineering. By design, the Control Room Envelope (CRE) pressure boundary is required to be maintained at a positive pressure during all modes of operation and during any irradiated fuel movement. New information contained in the MRE concluded the CRE function was not lost as the control room boundary door remained closed without manual assistance during normal operations. The amount of make-up air during normal operation is similar to the design flow for accident mode (approx. 800 cfm). It was concluded that the sealing integrity was not lost, thus the CRE function was maintained. The CRE would have remained operable and LCO 3.7.10 would not have been entered for the identified condition. The licensee has notified the NRC Senior Resident Inspector. Notified the R3DO (Valos). |
| Where | |
|---|---|
Cook  Michigan (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:+96.47 h4.02 days <br />0.574 weeks <br />0.132 months <br />) | |
| Opened: | Kelly Baker 14:10 May 29, 2014 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jun 20, 2014 |
| 50149 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Cook with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
WEEKMONTHYEARENS 524562016-12-22T04:00:00022 December 2016 04:00:00
[Table view]10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Emergency Diesel Generators Declared Inoperable ENS 501492014-05-25T13:42:00025 May 2014 13:42:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Control Room Ventilation Boundary Door Inoperable ENS 411112004-10-11T04:20:00011 October 2004 04:20:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Containment Ventilation Isolation System Inoperable During Fuel Movement 2016-12-22T04:00:00 | |