4 JAPAN’S NUCLEAR SAFETY REGULATION POLICY
87
system, accident countermeasures are the second area not at the discretion
of electricity utilities anymore but prescribed by NRA regulation.
Looking at safety requirements in detail, some are relative criteria,
whereas others are mandatory requirements. Relative ones pertain to
volcanic and earthquake-related risks. Their implementation depends on
underlying risk assessments and on the interpretation of how severe the
risk of an earthquake or a volcanic eruption is for each nuclear power
plant. Necessary earthquake resistance levels, for example, are determined by looking at possible sources of earthquakes around the plant and
the characteristics of the surface structure to determine ground motion.
Hence, they depend on how many and which possible sources for an
earthquake are considered.
Mandatory requirements were modelled after the types of interventions which could have prevented the events of the March 2011 nuclear
accident. They focus on preventing a loss of power, leading to a loss of
cooling capacity, followed by an increase in pressure inside the reactor,
ultimately erupting in a hydrogen explosion. For example, any plant
operator is required to build a tsunami protection wall, to install filter
vents and waterproof doors, and to provide backup electricity generators and reactor cooling systems. Absent from the new safety regulations
were new threats such as a cyber-attack on a nuclear reactor or other
IT-related safety requirements. While measures aimed at preventing an
accident like the one at Fukushima Daiichi were the strictest, the 2013
safety requirements failed to address new threats.
Safety Reviews
In contrast to what one might assume about a nuclear safety agency,
the NRA itself avoids expressions like “ensuring safety”. The term was
used by PM Abe himself when describing the NRA’s work. Asked about
this at a press conference, former Chairman Tanaka Shunichi laid out his
understanding of what the NRA does:
Safety is a vague term and says little about the degree of safety. As I
have mentioned many times before, we are conducting different compliance investigations from the point of view of lowering the risk as much
as possible. However, the understanding of what safety means differs from
person to person. Since it creates misunderstandings when we speak of
87
system, accident countermeasures are the second area not at the discretion
of electricity utilities anymore but prescribed by NRA regulation.
Looking at safety requirements in detail, some are relative criteria,
whereas others are mandatory requirements. Relative ones pertain to
volcanic and earthquake-related risks. Their implementation depends on
underlying risk assessments and on the interpretation of how severe the
risk of an earthquake or a volcanic eruption is for each nuclear power
plant. Necessary earthquake resistance levels, for example, are determined by looking at possible sources of earthquakes around the plant and
the characteristics of the surface structure to determine ground motion.
Hence, they depend on how many and which possible sources for an
earthquake are considered.
Mandatory requirements were modelled after the types of interventions which could have prevented the events of the March 2011 nuclear
accident. They focus on preventing a loss of power, leading to a loss of
cooling capacity, followed by an increase in pressure inside the reactor,
ultimately erupting in a hydrogen explosion. For example, any plant
operator is required to build a tsunami protection wall, to install filter
vents and waterproof doors, and to provide backup electricity generators and reactor cooling systems. Absent from the new safety regulations
were new threats such as a cyber-attack on a nuclear reactor or other
IT-related safety requirements. While measures aimed at preventing an
accident like the one at Fukushima Daiichi were the strictest, the 2013
safety requirements failed to address new threats.
Safety Reviews
In contrast to what one might assume about a nuclear safety agency,
the NRA itself avoids expressions like “ensuring safety”. The term was
used by PM Abe himself when describing the NRA’s work. Asked about
this at a press conference, former Chairman Tanaka Shunichi laid out his
understanding of what the NRA does:
Safety is a vague term and says little about the degree of safety. As I
have mentioned many times before, we are conducting different compliance investigations from the point of view of lowering the risk as much
as possible. However, the understanding of what safety means differs from
person to person. Since it creates misunderstandings when we speak of