ENS 40670
ENS Event | |
|---|---|
14:33 Apr 12, 2004 | |
| Title | Accident Mitigation - Common Control Room Emergency Air Conditioning System |
| Event Description | Salem Unit 2 was placed in a configuration that affected the ability to mitigate the consequences of an accident due to an inadvertent actuation of the common control room emergency air conditioning system (CREACS). CREACS was actuated as a result of an invalid safety injection signal initiated on April 12, 2004 at 1033 hours0.012 days <br />0.287 hours <br />0.00171 weeks <br />3.930565e-4 months <br />, during solid state protection system testing on Salem Unit-1. Salem Unit-1 is currently defueled. Salem Unit 2 is in Mode 1 at 100% power. Unit 2 has two shutdown LCOs in effect. The first is for the CREACS system, which is shared between Unit 1 & 2, being aligned for single train operation with the Unit 1 CREACS train out of service per LCO 3.7.6a. The second shutdown LCO is for two outside air intake dampers being inoperable for scheduled maintenance.
With Unit 1 having an invalid Safety Injection signal, the CREACS system actuates in accident pressurized mode. This mode of actuation starts the CREACS fans, isolates the Control Room Envelope from the normal control room ventilation system and aligns the two sets of CREACS outside air intake dampers. With a Unit 1 Sl signal, the Unit 1 CREACS intake dampers close and the Unit 2 CREACS intake dampers open. These damper positions are locked in until manually reset. With only one train of CREACS operable, the dose analysis indicates that the requirements of General Design Criterion (GDC) 19 can only be met during a the worst case design basis accident if the Unit 2 CREACS intake dampers are closed and the Unit 1 CREACS intake dampers open. Therefore, until the CREACS intake dampers were reset and realigned, Salem Unit 2 would not have been able to mitigate the consequences of an accident and is reportable in accordance with 10CFR50.72(b)(3)(v)(D). The CREACS system actuation was reset and the dampers were re-aligned to their pre-actuation alignment at 1232 hours0.0143 days <br />0.342 hours <br />0.00204 weeks <br />4.68776e-4 months <br />, restoring Salem Unit 2 to within the assumptions of the dose analysis. As a result of the Unit 1 Safety Injection signal, all available equipment started as designed. Since the SI signal has been determined to be invalid the start of this equipment is not reportable per 10CFR50.72(b)(3)(iv)(B). The Unit-1 Safety Injection signal has been cleared and an investigation of the cause is in progress. The only piece of major equipment out of service on Salem Unit 2 is the 25 Service water pump which is out of service for scheduled maintenance. The Licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Salem  New Jersey (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+1.17 h0.0488 days <br />0.00696 weeks <br />0.0016 months <br />) | |
| Opened: | Van Ford 15:43 Apr 12, 2004 |
| NRC Officer: | Arlon Costa |
| Last Updated: | Apr 12, 2004 |
| 40670 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |