emergency safety procedures to protect from core damage or meltdown. Because of the location of the reactor head damage, such a jet of reactor coolant might have damaged adjacent control rod drive mechanisms, hampering or preventing reactor shut-down. As part of the system reviews following the accident, significant safety issues were identified with other critical plant components, including the following: the containment sump that allows the reactor coolant to be reclaimed and reinjected into the reactor; the high pressure injection pumps that would reinject such reclaimed reactor coolant; the emergency diesel generator system; the containment air coolers that would remove heat from the containment building; reactor coolant isolation valves; and the plant's electrical distribution system. The resulting corrective operational and system reviews and engineering changes took two years. Repairs and upgrades cost $600 million, and the Davis–Besse reactor was restarted in March 2004. To replace the reactor vessel head, FirstEnergy purchased one from the mothballed Midland Nuclear Power Plant in Midland, Michigan. The NRC determined that this incident was the fifth-most dangerous nuclear incident in the United States since 1979, and imposed its largest fine ever — more than $5 million — against FirstEnergy for the actions that led to the corrosion. Criminal prosecutions In January 2006, First Energy, the owner of Davis–Besse, acknowledged a series of safety violations by former workers, and entered into a deferred prosecution agreement with the United States Department of Justice (DOJ). The deferred prosecution agreement related to the March 2002 incident. The deferment granted by the NRC were based on letters from Davis–Besse engineers stating that previous inspections were adequate. However, those inspections were not as thorough as the company suggested, as proved by the material deficiency discovered later. In any case, because FirstEnergy cooperated with investigators on the matter, they were able to avoid more serious penalties. The company paid $28 million under a settlement with the Justice Department. $23.7 million of that were fines, with an additional $4.3 million to be contributed to various groups, including the National Park Service, the U.S. Fish and Wildlife Service, Habitat for Humanity, and the University of Toledo as well as to pay some costs related to the federal investigation. Two former employees and one former contractor were indicted for statements made in multiple documents and one videotape, over several years, for hiding evidence that the reactor pressure vessel was being corroded by boric acid. The