ENS 40198
ENS Event | |
|---|---|
04:00 Sep 25, 2003 | |
| Title | Initiation of a Technical Specification Required Shutdown at Peach Bottom 2 |
| Event Description | On 09/25/03 @ 2210, while restoring reactor vessel instrumentation to service on Unit 3, an invalid ECCS actuation, (reactor vessel lo-lo-lo) occurred which caused all four (4) EDG to automatically start. All eight (8) 4 KV buses remained supplied from offsite sources. The Unit 3 ECCS pump auto starts were previously defeated per plant procedure and were not required to be operable per Tech Specs. The invalid ECCS initiation signal caused the offsite power Loss-of-Power instrumentation setpoints to transfer to the degraded voltage LOCA setpoints. With the degraded voltage LOCA setpoints initiated, the 4 KV E-bus fast transfer capability on a degraded voltage-NON-LOCA condition is defeated. With the inability to fast transfer the 4 KV E-buses on a degraded voltage NON-LOCA condition, both offsite sources are inoperable. Prior to restoring the reactor vessel level instrumentation, the E-2 diesel generator was inoperable. With both offsite source.; and one EDG inoperable, LCO 3.8.1 Required Action H.1 requires an entry into LCO 3.0.3 for Unit 2.
With Unit 3 in MODE 5, LCO 3.0.3 is not applicable. After one (1) hour, actions were taken to initiate a plant shutdown per LCO 3.0.3. No negative reactivity was added as the preparations were administrative in nature. At 09/26/03 @ 0006, the invalid ECCS initiation was removed. And all offsite Loss-of-Power instrumentation has been returned to OPERABLE status. Following the automatic start of all four (4) EDGs, E-1, E-3, and E-4 were successfully shutdown per plant procedures. E-2 could not be shutdown per plant procedures and was shutdown locally. The cause of the inability to shutdown E-2 per plant procedures is under investigation. E-2 EDG remains inoperable. The NRC Resident Inspector was notified by the licensee.
This 60-day optional report, as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10CFR50.73(a)(2)(iv)(A) to describe an unplanned, invalid actuation of a specified system, specifically the Units 2 and 3 Emergency Diesel Generators (EDGs).' 'On 9/25/03 at 2210 while restoring reactor vessel instrumentation to service on Unit 3, an invalid EDG start actuation signal on Reactor Vessel Lo-Lo-Lo level occurred which caused all four Emergency Diesel Generators to automatically start. Investigation into the cause of the event identified that the sequence of operating instrument valves associated with the instrument rack for level transmitters LT 72A and LT 72C resulted in the invalid reactor vessel lo-lo-lo reactor water level signal and subsequent EDG logic actuation. The EDGs initiated as expected for the given conditions. Off-site power was not affected and continued to supply power to the emergency busses. Once the reason for the EDG initiation was determined, the E-1, E-3, and E-4 EDGs were shut down per plant procedures from the Main Control Room by approximately 2255 hours0.0261 days <br />0.626 hours <br />0.00373 weeks <br />8.580275e-4 months <br />. The E-2 EDG could not be shut down normally from the Main Control Room control switch. It was later shut down at the local control panel in the E-2 EDG bay at about 0030 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> on 9/26/03. Repairs to the E-2 EDG control switch were completed in accordance with the Corrective Action Program (CR 177605).' 'Notification of the event to the NRC was initially made at 0125 on 9/26/03 (EN # 40198). Since the initial report, it was determined that a Technical Specification LCO 3.0.3 condition did not exist since the off-site sources were operable. This event has been entered into the site-specific corrective action program for resolution (CR 1776 10). The licensee has informed the NRC Resident Inspector. |
| Where | |
|---|---|
Peach Bottom  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+21.42 h0.893 days <br />0.127 weeks <br />0.0293 months <br />) | |
| Opened: | Todd Strayer 01:25 Sep 26, 2003 |
| NRC Officer: | Rich Laura |
| Last Updated: | Nov 10, 2003 |
| 40198 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Peach Bottom with 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.73(a)(1), Submit an LER | |
WEEKMONTHYEARENS 572212024-07-10T11:28:00010 July 2024 11:28:00
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