In September 2010, Reactor 3 was partially fueled by mixed-oxides (MOX).[36] There was no MOX (mixed oxide) fuel in any of the cooling ponds at the time of the incident. Earthquake tolerance[edit] The original design basis was a zero-point ground acceleration of 250 Gal and a static acceleration of 470 Gal,based on the 1952 Kern County earthquake (0.18 g, 1.4 m/s2, 4.6 ft/s2).[citation needed] Aft