depleted uranium. These assemblies were about 2.5 inches square by about 8 feet tall. Only the core section contained the enriched uranium while depleted uranium was placed above and below within the assemblies. The core also contained 2 control rods and 8 safety rods. The plant was designed for 430 MWt and 125 MWe using a newer uranium oxide fuel, but the plant was closed before the fuel was ever ordered. A 168 MWe oil-fired boiler was added in 1966 to utilize the turbine-generator during periods when the reactor was not producing power. The main cause of the partial meltdown was a temperature increase caused by a blockage in one of the lower support plate orifices that allowed the flow of liquid sodium into the reactor. The blockage caused an insufficient amount of coolant to enter the fuel assembly; this was not noticed by the operators until the core temperature alarms sounded. Several fuel rod subassemblies reached high temperatures of around (with an expected range near 580 °F, 304 °C), causing them to melt. Following an extended shutdown that involved fuel replacement, repairs to vessel, and cleanup, Fermi 1 restarted in July 1970 and reached full power. Due to lack of funds and aging equipment, it was finally shut down permanently on November 27, 1972, and was officially decommissioned December 31, 1975, under the definition of the Atomic Energy Commission (AEC). Later, the Nuclear Regulatory Commission (NRC) replaced the AEC and under their new definitions, Fermi was re-designated as being in SAFSTOR due to some remaining radioactivity at the site. On May 16, 1996, decommissioning was restarted. However, by November 2011 with very little activity remaining, a decision was made to halt further work. It is currently in SAFSTOR. Fermi 2 Fermi 2 is a 1,202 MWe General Electric boiling water reactor owned and operated by DTE Energy. Plans to build were announced in July 1968. Initial criticality was achieved in July 1985, and full commercial operation commenced on January 23, 1988. The reactor vessel holds 764 fuel assemblies and 185 control rods which modulate the power. The fuel assemblies are about square by about long. The original turbine generator was an English Electric unit. After a turbine blade incident in 1993, the company replaced the turbine with a General Electric unit. Water flowing through the reactor vessel changes to saturated steam and then travels to the main turbine-generator to