Referring to corrosion at the plant, FirstEnergy concluded: "Personnel failed to correctly apply key industry information and plant knowledge about the potential harmful effects of boric acid." It said plant personnel relied heavily on their belief that leakage of the control rod drive mechanism (CRDM) nozzles was a low probability. Plant personnel knew that cracking would eventually occur, but because the plant was relatively new, they thought they would see the phenomenon elsewhere before they saw it at Davis Besse.
But in its response to the report, the Nuclear Regulatory Commission (NRC) told FirstEnergy that the probability of unacceptable events is always low, and that FirstEnergy's attitude was not just that CRDM nozzle cracking was unlikely to happen, but that it "can't happen" - a state of "complete denial".
Among the specific flaws cited by FirstEnergy were "shallow cause analyses" with a focus on resolving symptoms rather than causes, corrective actions that deferred resolution or treated only symptoms, and a failure to recognise the collective significance of separate events.
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