International Nuclear and Radiological Event Scale (INES)

The International Nuclear and Radiological Event Scale (INES) is the international indicator to show the level of the seriousness in terms of safety of accidents or trouble at nuclear power plants.

The accident at TEPCO's Fukushima Daiichi NPS was evaluated as Level 7 (radiation impact converted to the amount of I-131 exceeds several tens of thousands TBq (10¹⁶ Bq)), equivalent to the level of the Chornobyl NPS Accident.
(Related to p.28 of Vol. 1, “International Nuclear and Radiological Event Scale”)

• Included in this reference material on March 31, 2013
• Updated on March 31, 2019