Following a drawn-out public meeting with managers, Jack Grobe, head of the NRC’s special Davis-Besse Oversight Panel said: “In a plant that has a solid operating history, human performance errors occur. The difference at Davis-Besse is that there is not a sound basis to believe that these are just minor blips. That is why we are questioning extensively the meaning of these errors. Are they blips or something else?”

The issues include an incident in which a worker failed to replace a cover plate, leaving a 15-centimetre hole in the plant floor and causing another employee to fall. Another minor failure occurred when an operator failed to check reactor conditions at a certain time. The check was only required because the repair of a broken meter had not been carried out to schedule.

The panel will meet again with plant officials in September, while two teams of independent industry experts will inspect Davis-Besse’s day-to-day operations and its safety culture.