motion that less attention was paid to the risk of tsunamis. Almost all of the
equipment for emergency power supply and emergency water injection were
located below the ground level, because the location is the best for protecting them
from seismic motion. Such consideration, however, did harm for protecting them
from tsunamis. We should have been more concerned about natural disasters other
than seismic motion.
The backup systems against station blackout were insufficient, because the
reliability of power grid is extremely high in Japan. The industry had made all
efforts to maintain the reliability of power grid as high as possible, and they are too
confident of it to think station blackout for a long period of time probable before
Fukushima. The multiple disasters over a very wide area after Tohoku Earthquake
easily denied such expectation and the external power supply from the grid became
completely unavailable. Relying just on the quality of power grid is vulnerable in
front of such multiple disasters.
Preparedness for all-hazards, unrestricted to natural disasters, is now a critical
issue of nuclear safety in Japan after Fukushima. Aircraft crashes and terrorists’
attacks should be considered also. Progress of these events may easily exceed the
conventional event scenarios, and it is difficult to take preventive countermeasures
to achieve prescribed design bases, in particular by installing some hardware
equipment. It is therefore unsuitable to cover all these hazards by safety regulation.
Meteorite strikes are out of the scope of design bases at present, but some response
scenario should be imagined as an unforced activity. What can we do if most of the
plant staff are down due to pandemic? Such questions must be asked behind the
nominal scene of regulation.
3.2 Administration of Emergency Response
Secondly, we should attend more to the administration of emergency response
rather than preventive measures with hardware equipment. While no casualties from
radiation exposure have been reported, many people died during or just after
evacuation due to improper evacuation planning and operation in Fukushima.
An offsite center, which is expected to be the local headquarter of nuclear
emergency response, was constructed in each area of major nuclear facility sites
after JCO. But the offsite center in the Fukushima area did not function at all due to
the blackout and a high radiation dose. The administrator failed to collect monitoring data of radiation dose and could not use SPEEDI (System for Prediction of
Environmental Emergency Dose Information) for decision-making in evacuation
planning, in particular for deciding which areas to be evacuated. It is because data
necessary for operating SPEEDI could not be transferred from the Safety Parameter
Display System (SPDS) at the plant site due to the loss of external power supply.
The Nuclear Safety Technology Center, which is an organization under the regulatory body, calculated the likely atmospheric dispersion of radioactive materials
using SPEEDI assuming a unit radioactivity release from the Fukushima site and
How the Fukushima Daiichi Accident Changed …
39
equipment for emergency power supply and emergency water injection were
located below the ground level, because the location is the best for protecting them
from seismic motion. Such consideration, however, did harm for protecting them
from tsunamis. We should have been more concerned about natural disasters other
than seismic motion.
The backup systems against station blackout were insufficient, because the
reliability of power grid is extremely high in Japan. The industry had made all
efforts to maintain the reliability of power grid as high as possible, and they are too
confident of it to think station blackout for a long period of time probable before
Fukushima. The multiple disasters over a very wide area after Tohoku Earthquake
easily denied such expectation and the external power supply from the grid became
completely unavailable. Relying just on the quality of power grid is vulnerable in
front of such multiple disasters.
Preparedness for all-hazards, unrestricted to natural disasters, is now a critical
issue of nuclear safety in Japan after Fukushima. Aircraft crashes and terrorists’
attacks should be considered also. Progress of these events may easily exceed the
conventional event scenarios, and it is difficult to take preventive countermeasures
to achieve prescribed design bases, in particular by installing some hardware
equipment. It is therefore unsuitable to cover all these hazards by safety regulation.
Meteorite strikes are out of the scope of design bases at present, but some response
scenario should be imagined as an unforced activity. What can we do if most of the
plant staff are down due to pandemic? Such questions must be asked behind the
nominal scene of regulation.
3.2 Administration of Emergency Response
Secondly, we should attend more to the administration of emergency response
rather than preventive measures with hardware equipment. While no casualties from
radiation exposure have been reported, many people died during or just after
evacuation due to improper evacuation planning and operation in Fukushima.
An offsite center, which is expected to be the local headquarter of nuclear
emergency response, was constructed in each area of major nuclear facility sites
after JCO. But the offsite center in the Fukushima area did not function at all due to
the blackout and a high radiation dose. The administrator failed to collect monitoring data of radiation dose and could not use SPEEDI (System for Prediction of
Environmental Emergency Dose Information) for decision-making in evacuation
planning, in particular for deciding which areas to be evacuated. It is because data
necessary for operating SPEEDI could not be transferred from the Safety Parameter
Display System (SPDS) at the plant site due to the loss of external power supply.
The Nuclear Safety Technology Center, which is an organization under the regulatory body, calculated the likely atmospheric dispersion of radioactive materials
using SPEEDI assuming a unit radioactivity release from the Fukushima site and
How the Fukushima Daiichi Accident Changed …
39