Browns Ferry - LOOP

Relatively lost in the tragedy in the southern part of the USA is the fact that Browns Ferry experienced a total Loss Of Offsite Power, causing all three reactor plants to shut down.

No. 1 and No. 2 plants were operating at 75% power, while No. 3 was at 100% power when the tornado damage caused a complete LOOP that generated trip signals on all three plants. All shutdown immediate actions were normal except for No. 3 plant; one MSIV or Main Steam Isolation Valve is indicating intermediate... meaning it's neither on the open seat or on the closed seat.

All site diesels except one which was down for maintenance started and ran normally.

The LOOP caused valid RPS signals, PCIS actuation and the mentioned EDG start. RPS signals of course included full scram.

Although the plants were using RCIC, on No. 1 the water level did reach -45 inches causing the HPIC system to actuate to restore water level in the reactor pressure vessel.

All three plants are in hot shutdown at this time.

These events began at 5:01 PM on the 27th.

10:30 PM Eastern Friday 4/29
ATOMIC POWER REVIEW