ML20135H295
| ML20135H295 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/14/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1992-004-00, LER 269-1992-019, LEr 269-1993-001, LER 269/1992-011, LER 269/1992-014, LEr 269/1992-016, LER 270-1992-004 | |
| Download: ML20135H295 (17) | |
Text
B-89 B.14.2 Event Description On October 19, 1992, Oconee 2 was operating at 100 power. Keowee Hydro Unit l (Keowee 1), one of the emergency power sources for the three Oconee units, was supplying power to the grid via.the overhead power path (see Fig. B.23). Keowee 2 was shut down and was aligned to provide emergency power via the underground path. Replacement of the 230-kV switchyard batteries was in progress:
battery SY-2 and charger SY-2 were disconnected, switcbyard
° de buses SY-DC-1 and SY-DC-2 were cross-tied, and charger SY-1 and battery SY-1 were powering both buses (see Fig. B.24).
Fag. B.23.
Emergency power distribution at Oconee (Original figure was illegible.)
LER NO: 270/92-004 Figure removed during SUNSI review.
B-90 Fig. B.24.
230-kV switchyard de power distribution at Oconee (Original figure was illegible.)
LER NO: 270/92-004 Figure removed during SUNSI review.
B-92 Fig; B.lS.
Keowee Hydro Station ac and de systems.* *
(Original figure was illegi*bl.)
apparently because of the spurious actuation of a lockout rely following a series of repetitive breaker operations that occurred as load center 1 X lost and regained power during the event. As a result, bus lX remained deenergized. ACB-8 failed to close because *of high resistance on a close *permissive contact, which caused auxiliary bus 2X to remain deenergized. The loss of these two buses resulted in the loss of all auxiliary power to the Keowee-units.. The Keowee control room lights went off, e annunciator panels went dark, and the telephone connection to Oconee and the alarm typer. *were lost.
At this point, the Keowee operator determined that" Keowee 2 wa:s running in the emgency mode.* The Keowee units continued to operate with their control functions supplied by batteries.
LER NO: 270/92-004 Figure removed during SUNSI review.