(CEI) and Toledo Edison (TE) and was named for former TE Chairman John K. Davis and former CEI Chairman Ralph M. Besse. Unit One Unit One is an 879 MWe pressurized water reactor supplied by Babcock & Wilcox. The reactor was shut down from 2002 until early 2004 for safety repairs and upgrades. In 2012 the reactor supplied 7101.700 GWh of electricity Units Two and Three In 1973, two more reactors were also ordered from Babcock & Wilcox. However, construction on Units Two and Three never commenced, and these two units were officially canceled in 1981. Electricity Production Incident history 1977 first stuck-open pilot-operated relief valve On September 24, 1977, the relief valve for the reactor pressurizer failed to close when the reactor, running at only 9% power, shut down because of a disruption in the feedwater system. 1985 loss of feedwater event On June 9, 1985, the main feedwater pumps, used to supply water to the reactor steam generators, shut down. A control room operator then attempted to start the auxiliary (emergency) feedwater pumps. These pumps both tripped on overspeed conditions because of operator error. This incident was originally classified an "NRC Unusual Event" (the lowest classification the NRC uses) but it was later determined that it should have been classified a "site area emergency". 1998 tornado On June 24, 1998 the station was struck by an F2 tornado. The plant's switchyard was damaged and access to external power was disabled. The plant's reactor automatically shut down at 8:42 pm and an alert (the next to lowest of four levels of severity) was declared at 9:18 pm. The plant's emergency diesel generators powered critical facility safety systems until external power could be restored. 2002 reactor head hole In March 2002, plant staff discovered that the borated water that serves as the reactor coolant had leaked from cracked control rod drive mechanisms directly above the reactor and eaten through more than six inches (150 mm) of the carbon steel reactor pressure vessel head over an area roughly the size of a football (see photo). This significant reactor head wastage on the exterior of the reactor vessel head left only of stainless steel cladding holding back the high-pressure (~2155 psi, 14.6 MPa) reactor coolant. A breach most likely would have resulted in a massive loss-of-coolant accident, in which reactor coolant would have jetted into the reactor's containment building and resulted in