ENS 45564
ENS Event | |
|---|---|
09:26 Dec 12, 2009 | |
| Title | Unusual Event Declared Due to Both Emergency Diesel Generators Being Inoperable |
| Event Description | A declaration of Unusual Event per EAL D.1-1 was made at 0126 PST on 12/12/09 due to both EDGs being inoperable. This condition places the Unit in a required Technical Specification Shutdown condition and the Unit is proceeding to shutdown.
Train "B" EDG was declared inoperable at 0025 PST on 12/11/09 due to annunciator issues associated with the EDG. The cause of the annunciator issues has still not been identified. This placed the licensee into the Action Statement for LCO 3.8.1 that required verification of operability of the Train "A" EDG within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. During the operability test of the Train "A" EDG, the diesel failed to reach voltage and frequency (the EDG tripped on startup) and it was also declared inoperable. As a result, the licensee entered Action F of LCO 3.8.1 and is required to be in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The licensee declared the UE at 0126 and commenced power reduction. Mode 3 must be reached by 0625 PST on 12/12/09 and Mode 5 must be reached by 1225 on 12/13/09. Besides the EDGs, all other safety related systems are operable. The licensee has notified State and local authorities and the NRC Resident Inspector.
On December 12, 2009, at about 0025 PST, SONGS Unit 3 Emergency Diesel Generator (EDG) 3G002 was determined to be inoperable. EDG 3G003 had been declared inoperable prior to this, resulting in both Unit 3 EDGs being inoperable. At about 0025 on December 11, 2009, EDG 3G003 (Train 'B') was declared inoperable as a result of work being done on an annunciator power supply. SONGS Technical Specifications (TS), section 3.8.1.B, requires that the associated EDG, 3G002 (Train 'A') be tested within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to ensure that the EDG was also not inoperable due to a common cause. On December 12, 2009, at about 0025, EDG 3G002 was declared inoperable when it did not achieve required voltage and frequency during an attempted start. SCE is reporting this occurrence as a loss of safety function in accordance with 10 CFR 50.72(b)(3)(v). The loss of both EDGs on Unit 3, per TS 3.8.1.E, requires restoration of one EDG within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. This action was not met, and as a result TS 3.8.1.F required the unit to be shutdown to Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. This shutdown action began at 0126 PST. Also, pursuant to the SONGS Emergency Plan, the shutdown of Unit 3 under TS 3.8.1.F required declaration of an Unusual Event. Both the TS required shutdown action and the declaration of the Unusual Event were reported to the NRC pursuant to 10CFR50.72 in an earlier notification (same NRC Operations Log #45564). SCE is taking actions to restore one of the EDGs to operability. At the time of this occurrence, Unit 2 was in a Steam Generator Replacement Outage, and Unit 3 was at approximately 100% power proceeding to a Mode 3 shutdown. The NRC Resident Inspector has been notified of this occurrence and will be provided with a copy of this report. Notified R4DO (Spitzberg).
The licensee exited their Unusual Event [and TS required shutdown] at 0645 PST based on restoration of operability of the "B" Train EDG. The "B" Train EDG annunciator issue was repaired and the EDG started and load tested per Technical Specification requirements. The EDG was declared operable at 0511 PST. The licensee is currently holding at 40% and planning to return to full power. Investigation into the starting problem of the "A" Train EDG is still ongoing. The licensee has notified the NRC Resident Inspector, State and local authorities. R4DO(Spitzberg), NRR(McGinty), and IRD MOC (Grant) notified. Also notified DHS (Inzer) and FEMA (Via). |
| Where | |
|---|---|
San Onofre  California (NRC Region 4) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | |
| Time - Person (Reporting Time:+-4.63 h-0.193 days <br />-0.0276 weeks <br />-0.00634 months <br />) | |
| Opened: | Steve Nelson 04:48 Dec 12, 2009 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Dec 12, 2009 |
| 45564 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (90 %) |
San Onofre with 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
WEEKMONTHYEARENS 499752014-03-29T04:10:00029 March 2014 04:10:00
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