When terrorists attempted to start a melt-down at Bakerline Nuclear Power Station, Alyssa Krull and her husband, Ben, were caught in the crossfire. The power station was flooded with radiation when core began to overload, killing Alyssa from the exposure.
In his heartbreak over Alyssa's death, Ben placed the blame on Superman, who didn't have enough time to evacuate the two from the power station. This led to Ben becoming the super-villain "Reactron" and one of the Man of Steel's greatest enemies. Over the next five years, Ben tried to kill Superman, and later Supergirl, as revenge for Alyssa's death.