The Davis-Besse Nuclear Power Station is located in Oak Harbor, Ohio on the southwest coast of Lake Erie. It has one nine hundred megawatt pressurized water reactor that was put into operation by FirstEnergy Nuclear Operating Company in 1977 and was licensed to operate until 2017. FirstEnergy Nuclear applied to the NRC for a twenty year license extension in 2010.
The population in the NRC plume exposure pathway zone with a radius of ten miles around the plant contains about nineteen thousand people. The NRC ingestion pathway zone with a radius of fifty miles around the plant contains about one million eight hundred thousand people. The NRC estimates that there is a very low risk of an earthquake that could damage the plant.
In 1977, the reactor was shut down because of problems with the feedwater when the relief valve for the pressurizer was stuck in the open position. The NRC ranks this as the fourth most dangerous safety incident at a commercial U.S. reactor since 1979 In 1985, the main pumps that supply water to the steam generators shut down. The operator made an error when he tried to start the emergency pumps. It took about a year and a half to repair the problems before the plant could be restarted. In 1988, there was a tornado that damaged the supply of external electrical power to the plant and the reactor had to be shut down until power could be restored.
In 2002, borated water that cools the reactor leaked from a cracked control rod drive above the reactor and ate a roughly one foot in diameter hole through six inches of the carbon steel reactor pressure vessel. Only three eights of an inch of steel was left to contain the high pressure reactor coolant. If the pressure vessel had been breached, a jet of superhot super pressurized coolant would have been released into the reactor’s containment building triggering emergency measures to shut down the reactor. If the jet had hit nearby control rod drives, it might have interfered with the shut down and resulted in a core meltdown. When the accident was analyzed, other problems with safety procedures were discovered including the containment sump, high pressure injection pumps, the emergency diesel generators, containment air coolers, reactor coolant isolation valves and the plant’s electrical wiring. It took two years and cost six hundred million dollars to repair the problems. Fines were leveled against the operators for safety and reporting violations. The NRC ranks this incident as the fifty most dangerous safety incident at a commercial U.S. reactor since 1979.
In 2003, the computer systems of the plant were infected with the Slammer computer worm and safety monitoring was lost of five hours. There was a small leak of tritium in 2008. In 2010, the operators of the plant discovered that one third of the nozzles in the replacement reactor vessel that had been installed in 2003 were corroding and could cause leaks of the borated water that corroded the original vessel. In 2011, a thirty foot long crack was discovered in the concrete shield building around the reactor containment vessel. In 2012, a small pinhole leak was discovered in a weld in the reactor coolant pump. The plant had to be put into limited operations while the problem was explored.
This is one of the most troubled nuclear power plants in the United States with the dubious distinction of being the location for two of the five most dangerous incidents since 1979. The original design was flawed, equipment failed, dangerous system problems went unnoticed or unreported, tornados damaged power supplies, the NRC had to review procedures and design issues, computer worms invaded the computer system, etc. There are a number of groups that strongly oppose the relicensing of the aging Davis-Besse and they are fighting to prevent it.
