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ZION UNIT 2 LOSS OF NSSS CONTROL ROOM ANNUNCIATORS

Zion Unit 2 was operating at 100% power when a blown fuse caused the loss of the ability to silence and reset about half the visual and audible main control board alarm annuniciators. The annunciators that were lost were those that alarm in the event of abnormal conditions or actuations of 1) safeguards components (e.g.containment spray, auxiliary feed, and service water), 2) reactor coolant components (e.g., rod control and reactor coolant pumps), and 3) safeguards buses normally supplied by the emergency diesel generators. Within 25 minutes, control room operators replaced the blown fuse and satisfactorily tested the annunciators. The plant remained operating at 100 percent power throughout the event.

Location: ZION-2
Event date: Mon, 15-03-1993
Nuclear event report
Legenda & explanation