05000311/LER-2004-003
| Salem | |
| Event date: | 1-2-2004 |
|---|---|
| Report date: | 06-11-2004 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident |
| 3112004003R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
Control Room Emergency Air Conditioning System {VI) (CREACS) Solid State Protection System {JG}(SSPS) * Energy Industry Identification System {EIIS} codes and component function identifier codes appear as {SS/CCC}
IDENTIFICATION OF OCCURRENCE
Event Date: April 12, 2004 Discovery Date: April 12, 2004
CONDITIONS PRIOR TO OCCURRENCE
Salem Unit 2 was in Mode 1 (POWER OPERATION) at the time of the event.
Salem Unit 1 was defueled Salem Unit 1 was defueled in its sixteenth refueling outage (1R16). Salem Unit 2 was operating at approximately 100% Rated Thermal Power (RTP) with two shutdown Limiting Condition for Operations (LCO) in effect. The first LCO was for the Control Room Emergency Air Conditioning System {VI}(CREACS), and the second LCO was for the outside air intake dampers {DMP} being out of service for scheduled maintenance. The Salem Units 1 and 2 common Control Room share the CREACS, one train per unit with each train containing: two fans and associated outlet dampers, one cooling coil, one charcoaVHEPA filtration unit and return air isolation dampers. Salem Technical Specifications 3.7.6.1 and 3.7.6 for Salem Units 1 and 2, respectively, provide a full description of the requirements.
The Salem Unit 1 Control Room Emergency Air Conditioning System train was out of service for normal refueling maintenance activity.
DESCRIPTION OF OCCURRENCE
On April 12, 2004 at approximately 10:33 during maintenance of the Salem Unit 1 Solid State Protection System (JG)(SSPS) an invalid safety injection signal was generated. As a result of the invalid safety injection signal, the CREACS system actuated to its accident pressurized mode alignment. This alignment includes the start of the CREACS fans, isolating the control room envelope from the normal control room ventilation system and aligning the emergency outside intake air dampers to the non-affected unit.
emergency intake air dampers closed and the Salem Unit 2 dampers opened. Once the dampers actuated to their required position, these dampers were locked out from manual operation until the safety injection signal was reset; then the dampers were manually reconfigured as needed.
I� DESCRIPTION OF OCCURRENCE(cont'd) The control room ventilation system configuration following the safety injection signal was one train of CREACS operating with the emergency outside air intake dampers for Salem Unit 2 open and the Salem Unit 1 emergency outside air intake dampers closed.
With the CREAC System actuated to its accident pressurized mode alignment as described above, Salem Unit 2 was in a condition where it would not have been able to mitigate the consequences of an accident.
The Salem dose analysis performed to meet the requirements of the General Design Criterion (GDC) 19 states that with only one train of CREACS available at the start of a design basis accident, the make up air supply to pressurize the control room envelope must be supplied by the non-accident Unit's emergency outside air intake. In this particular event, for the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> period that it took operators to reset the CREACS actuation signal, the Salem Unit 2 emergency outside air intake dampers would not have been able to close if demanded to by an accident signal in Unit 2, therefore failing to achieve the acceptable configuration assumed in the dose analysis with only one train of CREACS operable.
On April 12, 2004 at approximately 12:32, the CREACS actuation signal was reset and the CREACS system was placed back in its normal standby alignment, thereby returning Salem 2 to a condition where it would have been able to mitigate the consequences of an accident.
This condition is reportable under 10 CFR 50.73(a)(2)(v)(D).
CAUSE OF OCCURRENCE
A defective universal card A207 caused the inadvertent safety injection in Unit 1. The safety injection signal occurred when the A207 card was moved from one position in the SSPS cabinet to another position in the SSPS cabinet, while in the process of maintenance troubleshooting activities.
The initial investigation of the SSPS cards revealed that the safety injection signal generated in a failed portion of the circuit card when it was inserted into the low pressurizer pressure safety injection position.
The failed part of the card (a malfunctioning Isolator card) was not used in its prior position, thus the failed circuit was previously undetected.
PREVIOUS OCCURRENCES
A review of LERs at Salem and Hope Creek Generating Stations for the years 2002 and 2003 did not identify any previous similar events as stated in the apparent cause of occurrence such that this event could have been prevented by previous corrective actions.
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SAFETY CONSEQUENCES AND IMPLICATIONS
There were no safety consequences associated with this event.
Although the CREACS was aligned in a configuration that was non-conforming to the Salem dose analysis assumptions, the time duration of this non-conformance was limited, and no design basis events occurred that required the system to automatically respond.
A review of this event determined that a Safety System Functional Failure (SSFF) as defined in NEI 99-02 did occur.
CORRECTIVE ACTIONS
1. The defective card was replaced.
2. A full functional test procedure on Train B was performed satisfactory.
3. Maintenance will determine a minimum quantity of refurbished/ tested circuit cards needed to be kept available for troubleshooting and Work Management will create a scheduled operation within the work management process to dedicate the required resources to refurbish and test the needed circuit cards.
4. An operating experience report will be issued relative to this event.
COMMITMENTS
The corrective actions cited in this LER are voluntary enhancements and do not constitute commitments.