Emergency Diesel Generators (EDGs)

Nuclear Reactors need electricity to operate – without a supply their safety systems would be disabled. They do not generate their own electricity. Like all of us, they depend on the grid – offsite power. 

If offsite power fails, they depend on back up generators (EDGs). The generators are designed to supply electricity to keep coolant circulating to prevent the reactor core from heating and causing a meltdown; and to keep the spent fuel pool water cool to prevent the rods from melting and/ or catching fire. If the EDGs fail, the chance of an accident approaches certainty – the reactor can not be restarted without offsite power. Terrorist attacks, ice or wind storms – Nor’ Easters- can knock out transmission lines to nuclear reactors for extended periods.

There is a history of problems in the industry with emergency diesel generators – in some cases all emergency diesel generators at a reactor were inoperable at once. Nearly every month, the EDGs fail at some reactor; fortunately not none have yet during a station blackout. Emergency diesel generator problems have occurred at Pilgrim – the latest event reported was in September 2002.

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