The International Atomic Energy Agency’s final
report on the March 2011 triple meltdowns at Tokyo Electric Power
Co.’s Fukushima No. 1 nuclear power plant puts the main blame on
the then prevailing assumption that Japan’s “nuclear power plants
were so safe that an accident of this magnitude was simply
unthinkable.” Constant monitoring is needed to make sure the
government, power companies and nuclear regulatory authorities aren’t
falling into the same “safety myth” as they push to reactivate
idled reactors that meet what is now touted as the “world’s most
stringent” nuclear safety standards.
Last week, Kyushu Electric Power Co. began commercial operation of
the No. 1 reactor of its Sendai nuclear power plant in Satsumasendai,
Kagoshima Prefecture — a little over a month after it became the
first reactor idled since 2011 to be reactivated on the basis of the
safety standards that were tightened in response to the Fukushima
disaster. The utility plans to restart the plant’s No. 2 reactor as
early as next month, and the Abe administration and the power
industry are pushing to bring more idled plants back online once they
have cleared the Nuclear Regulation Authority’s screening.
The regulatory system for nuclear power generation has been
reformed since the 2011 crisis. The old Nuclear and Industrial Safety
Agency, which came under fire for the Fukushima debacle, has been
replaced by the NRA, and new regulations introduced in 2013 require
operators of nuclear power plants to beef up their defense against
natural disasters such as major earthquakes and tsunamis. But while
the NRA itself states that compliance with the new standards does not
guarantee the plants’ safety, the government says the plants are
ready for restart because they meet the NRA criteria. No one appears
ready to take final responsibility for the plants’ safety.
The IAEA report, compiled by around 180 experts from 42 countries
and submitted to an annual general conference of the United Nations
nuclear watchdog this week, highlights the “assumption” held by
Japan’s nuclear plant operators prior to 2011 that a crisis of that
magnitude would not happen, which was never challenged by the
government or regulatory authorities, leaving the nation unprepared
for a severe accident.
The Fukushima power plant lost its emergency power supply after it
was flooded by a 15-meter tsunami triggered by the magnitude-9 quake
on March 11, 2011. The loss of power crippled its crucial
core-cooling functions and led to the meltdowns in its three
operating reactors. Citing Tepco’s failure to take precautionary
action against such external hazards despite an estimate prior to the
disaster that a powerful quake off Fukushima could cause a tsunami of
roughly the same scale that hit the plant site, the report said
“there was not sufficient consideration of low probability, high
consequence external events,” partly because “of the basic
assumption in Japan, reinforced over many decades, that the
robustness of the technical design of the nuclear plants would
provide sufficient protection against postulated risks.” This
assumption led to “a tendency for organizations and their staff not
to challenge the level of safety” and “resulted in a situation
where safety improvements were not introduced promptly.”
The report also pointed to the deficiencies in Japan’s nuclear
regulatory system behind the Fukushima disaster. “The regulation of
nuclear safety in Japan at the time of the accident was performed by
a number of organizations with different roles and responsibilities
and complex interrelationships. It was not fully clear which
organizations had the responsibility and authority to issue binding
instructions on how to respond to safety issues without delay,” it
said. “The regulations, guidelines and procedures in place at the
time of the accident were not fully in line with international
practice in some key areas, most notably in relation to periodic
safety reviews, re-evaluation of hazards, severe accident management
and safety culture.”
IAEA Director General Yukiya Amano, in his foreword to the report,
says Japan’s regulatory system has since been reformed to meet
international standards, with regulators given clearer
responsibilities and greater authority. Whether the new plant safety
standards are the world’s most stringent or not, plants that meet
the standards are supposed to withstand much greater levels of
external hazards and be better able to respond to emergencies than
before.
Still, complacency under the new standards would risk reviving the
same safety myth rebuked in the report. Questioning whether the
tightened standards are sufficient could be branded as demanding zero
tolerance of risks and thereby unrealistic. However, as the IAEA
report points out, it was an “unlikely combination of events”
that hit the Tepco plant, and the utility’s unpreparedness for such
a situation that resulted in the 2011 disaster.
We need to consider whether the tendency to dismiss
low-probability risks as “small enough” — as was, for example,
the risk of Kyushu Electric’s Sendai plant being hit by a volcanic
eruption when the go-ahead was given for its restart — is
acceptable from the viewpoint of preventing severe accidents at
nuclear plants in the future.
Source: Japan Times
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