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DOE's Safety Bulletin No. 2011-01, Events Beyond Design Safety Basis Analysis, March 2011

PURPOSE

 
This Safety Alert provides information on a safety concern related to the identification and mitigation of events that may fall outside those analyzed in the documented safety analysis.

BACKGROUND

On March 11 , 2011 , the Fukushima Daiichi nuclear power station in Japan was damaged by a magnitude 9.0 earthquake and the subsequent tsunami. While there is still a lot to be learned from the accident about the adequacy of design specifications and the equipment failure modes, reports from the Nuclear Regulatory Commission (NRC) have identified some key aspects of the operational emergency at the Fukushima Daiichi nuclear power station.  Specifically, following automatic shutdown of the operating reactors due to the earthquake, a complete loss of both the offsite and on-site power systems disabled key cooling systems which eventually led to fuel damage, hydrogen generation, and high radiation levels within the facility.