Even as the events at Japan’s Fukushima Daiichi nuclear plant were unfolding, the U.S. industry began analyzing the situation and compiling data that would inform the industry’s lessons learned.
The Electric Power Research Institute’s Modular Accident Analysis Program (MAAP) software analyzes the progression of events during an accident. It captures many possible outcomes in a short timeframe. Unlike other codes, MAAP runs faster than accidents progress so it can actually guide emergency responders. Now in its fifth version, the tool has informed changes to industry guidelines that plant operators use to respond to accidents.
Because of Fukushima Daiichi’s rapid power loss, there is virtually no plant data from the accident’s early hours, data critical to understand the incident’s progression. MAAP filled in many data gaps, leading to critical lessons to help the global nuclear industry improve plant design and accident response guidelines.
One lesson from MAAP: Plant operators need a detailed strategy for using portable equipment, such as pumps to inject cooling water into reactors. Portable equipment strategies should buy time for plant operators to retrieve the equipment. For boiling water reactor nuclear plants such as Fukushima, this might involve devising a way for the plant’s existing reactor core isolation cooling system to function temporarily after a loss of power.
Nearly all U.S. companies that operate nuclear plants use MAAP analyses to develop the portable equipment plans they submit to regulators. Lessons from the MAAP Fukushima analyses have been incorporated into the industry’s severe accident management guidelines. That helps reactor operators prepare for and navigate potential accidents.