ENS 40600
ENS Event | |
|---|---|
19:08 Mar 19, 2004 | |
| Title | Hpci System Declared Inoperable at Limerick 1 Due to a Broken Hand Switch |
| Event Description | On 3/19/04 at 14:08 PM EST, the Unit-1. HPCI system was declared inoperable due to a hand-switch failure, which prevented main control room operation of the HV-055-1F0O1 HPCI steam admission valve. The system had just successfully completed its functional surveillance test and the switch broke resulting in the operators using an, alternate means to shutdown the HPCI system. The steam admission valve is not a PCIV. The valve was open all the time; the system was shutdown using an alternate procedure. The system is now blocked for hand-switch replacement. This report is being made pursuant to 10CFR50.72(b)(3)(v) for failure of a single train accident mitigation system.
The NRC Resident inspector was notified. Operators entered the unit into a 14 day LCO for declaring HPCI system inoperable.
This is a retraction of the event notification made on 3/19/04 at 21:00 hours. This event (#40600) was initially reported as a safety system functional failure under the requirement of 10CFR50.72(b)(3)(v)(D). Unit 1 High Pressure Coolant Injection (HPCI) system was declared inoperable due to a handswitch failure that prevented operation of the HV-055-1F001 HPCI steam admission valve from the main control room. The handswitch failed while attempting to close the steam admission valve during system shutdown at the conclusion of surveillance testing. The operator then closed the outboard steam line isolation valve to complete the system shutdown. HPCI is automatically initiated by low reactor level or high drywell pressure signals. Manual HPCI initiation for inventory makeup is performed by depressing the initiation pushbutton. Both automatic initiation and manual initiation using the pushbutton open the steam admission valve. The failed handswitch did not adversely affect the initiation of the HPCI system in the inventory makeup mode. The manual startup of the system in the test mode of operation is unavailable when the handswitch is failed. The test mode can be used to remove decay heat following an isolation of the main steam lines but it is not a credited safety function. The steam admission valve handswitch would not be used to shutdown the system when an automatic initiation signal is present; the outboard steam line isolation valve would be closed to secure the system. This is the method that was used to secure the system during the surveillance test. The handswitch is mainly used to startup and secure the system during surveillance testing. The system was removed from service as part of a planned evolution to conduct surveillance testing in accordance with an approved procedure and the plant's Technical Specifications. The system was secured for the purpose of concluding the surveillance test and replacing the handswitch. The failed handswitch did not adversely affect the systems capability of performing its safety function. A condition did not exist at the time of discovery that could have prevented the fulfillment of the HPCI safety function. Notified R1DO (B. MCDERMOTT). |
| Where | |
|---|---|
Limerick  Pennsylvania (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:+1.87 h0.0779 days <br />0.0111 weeks <br />0.00256 months <br />) | |
| Opened: | Dan Semeter 21:00 Mar 19, 2004 |
| NRC Officer: | Rich Laura |
| Last Updated: | Apr 14, 2004 |
| 40600 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (15 %) |
| After | Power Operation (15 %) |