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Japan's Nuclear Crisis Raised to INES Scale 7.0, same scale as Chernobyl

The nuclear crisis at the Fukushima Daiichi plant in Northern Japan was raised to International Nuclear Events Scale 7.0, the same level as the Chernobyl crisis which took place in UKraine in 1986. Fukushima Daiichi Nuclear crisis was triggered by a 9.0 Earthquake (on a richer Scale) which occurred in Japan's northern region on March 11, 2011. The earthquake resulted in the automatic disconnection of the power source to the nuclear plant's cooling system. The earthquake was followed by heavy tsunami which flooded the backup generators and caused the 3 nuclear reactors (reactors 1, 2 and 3) at the Fukushima Daiichi nuclear plant to overheat. The fuel (uranium) rods were exposed.

There was also fire in the nuclear reactor 4 which was one of the 3 reactors shut down for maintenance purpose before the earthquake. High rates of radiation from the Fukushima Daiichi plant have been recorded in water, food and soil at locations in close vicinity to the plants. Furthermore there have been leakages of radiative core materials. Japanese Authorities issued evacuation orders to people living within 20 kilometres of the first plant and within 10 kilometres of the second plant. Furthermore, people living within 30 kilometres of the first plant are asked to remain indoors and close all windows.

 The radiations and leaking from the damaged Fukushima Daiichi plant, albeit reportedly slowing down, has been occurring continuously since the event started in mid-May 2011. The continuous release of radiations has prompted the Japanese authorities to increase the INES severity rating of the crisis from 4.0 (similar to Three Mile Island) to 7.0 (Similar to Chernobyl). Each reactor accident was rated separately. Out of the six reactors, three were rated level 5, one was rated at a level 3, and the situation as a whole was rated level 7. Chernobyl's radiations were sudden and huge, whereas the Fukushima Daiichi's is gradual and continuous. The Japanese authorities (Japanese government's nuclear safety agency) might have made the decision based on the cumulative radiations coming out of Fukushima Daiichi plant.

INES is a tool for promptly communicating to the public in consistent terms the safety significance of reported nuclear and radiological incidents and accidents, excluding naturally occurring phenomena, such as radon. The scale can be applied to any event associated with nuclear facilities, as well as the transport, storage and use of radioactive material and radiation sources (International Atomic Energy Agency). The INES scale ranges from 1 to 7 with 1 to 3 representing incidents and 4 to 7 representing accidents as follows:

Accidents:

7    Major Accident
6    Serious Accident
5    Accident with wider consequences
4    Accident with local consequences

Incidents:

3    Serious incident
2    Incident
1    Anomaly
0    Deviation (No Safety significances)

In the meantime, authorities said the radiations from the plant is slowing down and hoped that the plants will be stabilized soon. The nuclear crisis and the preceding earthquake and tsunami of March, 2011 have caused Japan a great deal in infrastructure and human losses. Over 13,000 people are reportedly dead, close to 15,000 people are missing while several thousands have been made homeless. Several houses and public infrastructures were destroyed. The cost of repairs will be huge.

Other Sites:

• Fukushima Nuclear Accident Update Log
• World Nuclear Association - Chernobyl Disaster
• Nuclear Energy
• International Nuclear and Radiological Event Scale. Other links: INES HTML - (IAEA Website) or INES pdf  - (IAEA Website)
• Japan's Nuclear Crisis Raised to INES Scale 7.0, same scale as Chernobyl