One very crucial difference between the two accidents concerns the structural designs of the reactors.

Nine months after the disaster at the Fukushima nuclear power plant, Japan is working to contain radiation exposure in the region of the accident. The challenges confronting the country in this endeavour are shown by the new ENSI report on the radiological effects of the accident on 11 March 2011.

The analysis of the accidents at Fukushima confirms that Swiss nuclear plants are safe. However, the Swiss Federal Nuclear Safety Inspectorate (ENSI) has identified a variety of findings (Lessons Learned) from Fukushima which should now be utilised to continue optimising the safety of Switzerland’s nuclear power plants.

The International Nuclear Event Scale (INES) is used to classify safety-related events in nuclear plants on a scale from 1 to 7.

What happened at Fukushima Dai-ichi was a major nuclear accident, as was also the case at Chernobyl. However, there are significant differences between the two events: at Chernobyl, the nuclear chain reaction went out of control, and power increased abruptly by a factor of several hundred.