ENS 45628
ENS Event | |
|---|---|
19:25 Jan 13, 2010 | |
| Title | Wrong Train of Emergency Core Cooling System Removed from Service |
| Event Description | On January 13, 2010, at about 1125 PST, Train A suction piping from the SONGS Unit 3 Refueling Water Storage Tank (RWST) was determined to be inoperable following detection of weld flaw indications during ultrasonic testing. Due to miscommunication, operators mistakenly declared the Train B Emergency Core Cooling System (ECCS) header inoperable at about 1125 and removed DC control power to the Train B ECCS pumps. This resulted in both trains of Unit 3 ECCS being inoperable and entry into the Technical Specification (TS) 3.0.3 one-hour shut down action. At 1140 PST, the DC control power was restored to the Train B ECCS pumps, Train B ECCS was declared operable, and TS 3.0.3 was exited. SCE is reporting this in accordance with 10 CFR 50.72(b)(3)(v) as an event that could have prevented the fulfillment of a safety function.
SCE is further evaluating the indications found on Train A piping to determine if the piping is capable of performing its safety function. At the time of this occurrence, Unit 2 was in a Steam Generator Replacement Outage, and Unit 3 was at approximately 100% power. The licensee notified the NRC Resident Inspector.
On January 13, 2010, SCE reported that both trains of Unit 3 Emergency Core Cooling System were inoperable for approximately 15 minutes because Train B ECCS was mistakenly taken out of service when weld flaw indications were found on Train A ECCS piping. This resulted in a condition that could have prevented the fulfillment of a safety function. Consequently, both trains of ECCS in Unit 3 were declared inoperable and the unit entered into Technical Specification 3.0.3 at 1134 PST (Time of Discovery). At 1140 PST, Train B ECCS was declared operable and TS 3.0.3 was exited. Event Notification 45628 was conservatively made because, although Train A ECCS piping remained capable of performing its safety function, this was not yet formally documented at the time the 8-hour report was due. Subsequently, an engineering evaluation was completed at 2308 PST on January 13, 2010, that demonstrates the as-found condition of the Train A ECCS piping was operable because the flaw meets the evaluation criteria of ASME Boiler and Pressure Vessel Code Case N-513-2. Since Train A ECCS piping was operable, this event did not constitute a condition that could have prevented the fulfillment of a safety function and is not reportable under 10 CFR 50.72(b)(3)(v)(D). Consequently, SCE is retracting the phone report to the NRC on January 13, 2010. The NRC Resident Inspector will be informed of this report. Notified R4DO (Werner). |
| Where | |
|---|---|
San Onofre  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+3.3 h0.138 days <br />0.0196 weeks <br />0.00452 months <br />) | |
| Opened: | Lee Kelly 22:43 Jan 13, 2010 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Jan 19, 2010 |
| 45628 - NRC Website
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Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
San Onofre with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
WEEKMONTHYEARENS 456282010-01-13T19:25:00013 January 2010 19:25:00
[Table view]10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Wrong Train of Emergency Core Cooling System Removed from Service ENS 442472008-05-29T18:36:00029 May 2008 18:36:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Offsite Power Below 59.7 Hz ENS 442272008-05-20T20:10:00020 May 2008 20:10:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Offsite Power Grid Disturbance ENS 423102006-02-04T02:15:0004 February 2006 02:15:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Offsite Power Not within Specifications ENS 417982005-06-26T11:17:00026 June 2005 11:17:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Edg Inoperable Due to Loose Electrical Connection ENS 408182004-06-14T14:41:00014 June 2004 14:41:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Licensee Declared Offsite Power Inoperable Due to Dip in Grid Frequency 2010-01-13T19:25:00 | |