During the 2011 earthquake and resultant 15+ meter tsunami on the east coast of Japan, the Fukushima I nuclear power plant suffered core damages at three of its six reactors after the emergency core cooling systems failed due to the extreme beyond design basis conditions. That is, the Fukushima plants did not consider a tsunami above in their original design. These reactors were General Electric BWR-3 and BWR-4 reactors inside Mark I containment designs, which is common in the United States. However, all of these types of plants have varying designs due to regulations, individual utility preferences, and construction location. In 1995, Sandia National Laboratories estimated that the individual BWR-3 and BWR-4 reactors in the United States have a core damage frequency between 10−4 and 10−7.