The Accident at TEPCO's Fukushima Daiichi Nuclear Power Station
Reassessed to be Level 7 on INES
But substantially different from the Chernobyl accident

April 20, 2011

On April 12, Japan made assessment and announced that the accident at Tokyo Electric Power Company (TEPCO) Fukushima Daiichi Nuclear Power Station corresponded to Level 7 on the International Nuclear Event Scale (INES).

At the same time, however, as emphasized by Japan, this new assessment does not mean that the situation in Fukushima is aggravating. The new assessment is a result of the latest calculation, based on newly obtained data of the total amount of radioactive substances released, in accordance with the IAEA criteria.

Furthermore, most of the radioactive substances were released in the first few days of the accident and the airborne radiation dose has been gradually declining. For example, in Tokyo, its radiation dose has never reached to the level which would affect the human health. It has been declining steadily. The current data shows that it has returned to an approximately normal level. Radioactive monitoring will be continued.

The causes and the aspects of the accident at the Fukushima are very different from those of the Chernobyl accident.

First, while the reactor itself exploded at Chernobyl, the reactors at Fukushima automatically shut down and there was no large-scale fire at the site. The IAEA also points out that the two accidents are different in this regard.

Secondly, the total amount of radioactive substances released from the Fukushima plant at present is estimated to be far less than that of the Chernobyl.

Thirdly, there is neither loss of life by radioactive exposure nor health problem caused by radiation among residents in the vicinity of the nuclear power station.

Although the two accidents are assessed as the same level 7, IAEA explains that the two differs substantially, for the Fukushima reactors suspended their operations after the earthquake, whereas in Chernobyl the fire broke out and nuclear materials were diffused while the reactors were in operation.

After the reassessment on April 12, international organizations such as International Civil Aviation Organization (ICAO), International Maritime Organization (IMO) and World Health Organization (WHO) have made objective assessments that excessive measures, such as general travel restriction to Japan are not needed. Those international organizations stated in their joint press briefing dated 14 April 2011 that they remain confident that current radiation levels do not present health or transportation safety hazards to passengers and crews.

ICAO and IMO stated on April 14 and 15 respectively as follows: "Radiation monitoring around airports and seaports in Japan continues to confirm that levels remain well within safe limits from a health perspective. In addition, monitoring of passengers, crew and cargo from Japan carried out to date in other countries, in accordance with their national policy, does not suggest any health or safety risk. Therefore, screening of radiation for health and safety purposes is currently considered unnecessary at airports and seaports around the world."

Noting the Japanese reassessment, WHO stated on April 13 as follows: "Public health risks beyond the 30km evacuation zone around the plant are currently still low. The latest monitoring of radiation levels in air, drinking water and soil reveal declines in all three. Local authorities review restrictions on food sales on a weekly basis. The International Food Safety Authorities Network (INFOSAN) - a joint WHO/FAO initiative - provides regular updates to the 177 countries belonging to the network, one of which is Japan."

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