The Chuetsu-oki Earthquake in Niigata and Safety of the Kashiwazaki-Kariwa Nuclear Power Plant
July 27, 2007
- The Chuetsu-oki Earthquake in Niigata prefecture, Japan, which occurred
on July 16th 2007, caused widespread damages such as collapse of houses
and buildings in the prefecture and its surrounding areas as in Nagano prefecture.
It also triggered a fire at an electrical transformer and other problems
in the Kasiwazaki-Kariwa Nuclear Power Plant.
- However, no problems have been confirmed with regard to the safety of
the nuclear reactors as four of the plant’s seven reactors running at the
time of the earthquake were all shut down automatically by a safety mechanism.
- Due to the earthquake, an insignificant amount of radioactive materials
were released from No 7 unit of the plant into the air, and water containing
radioactive materials were released from No 6 unit into the sea. But the
effect of the radiation due to the release of radioactive materials into
the air is as low as one-10 millionth (1/10, 000, 000), and that into the
sea is as low as one-billionth (1/ 1, 000, 000, 000) of the radiation which
normal citizens would receive from the natural environment in a year, respectively.
These radioactivity levels of the releases into the air and the sea are
as low as one-millionth(1/1,000,000), and one-100 millionth(1/1,000,000,000),
respectively, of the radiation which normal citizens would receive during
a round-trip flight from Tokyo to New York. Needless to say, the levels
are much lower than the legal limit set by the safety standard, and will
never affect the surrounding environment. Furthermore, these leaks have
- In spite of the facts above, it is most regrettable that some news media
have reported on the safety situation surrounding the nuclear power plant
in an inaccurate or inappropriate manner, and spread of misperception has
produced adverse effects on such fields as tourism in Japan.
- Japan has provided and shared relevant information with the International
Atomic Energy Agency (IAEA) since the beginning. Considering the proposal
by the IAEA that although it is confident in Japan’s ability to perform
a thorough assessment of this event, the IAEA is ready to send an international
expert team to join Japan in the review, Japan has determined to accept
the team from IAEA and to conduct a joint review from the viewpoint
of improving international cooperation in the field of nuclear safety.
- We believe that this joint review will not only confirm the current safety of the Kashiwazaki-Kariwa Nuclear Power Plant, more objectively, but also will further contribute to the transparency in Japan’s Nuclear Energy, and help promote to share lessons leaned from the earthquake internationally.