According to a report by the U.S. Nuclear Regulatory Commission into the Fukushima Daiichi nuclear disaster , the March 2011 Tōhoku earthquake and tsunami that caused that disaster was an event " far more severe than the design basis for the Fukushima Daiichi Nuclear Power Plant " . The reactors at this plant were BWR 3 and BWR 4 models . Their primary containment vessels had to be flooded with seawater containing boric acid , which will preclude any resumption of operation and was not anticipated in the DBA scenario . In addition , nothing similar to the chemical explosions that occurred at the Fukushima Daiichi plant was anticipated by the DBA
2011 Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
Boiling water reactor safety systems