Three months on, and the impact of the crisis at the Fukushima Daiichi nuclear plant is still unfolding. On 6 June, Japan鈥檚 raised its estimate of the radioactive material emitted.
Following a massive underestimate straight after the earthquake and tsunami that triggered the crisis, in April NISA said that between 370,000 and 630,000 terabecquerels were released between 11 and 15 March, putting the crisis at level 7, the most severe category on the international scale used to rate nuclear accidents.
Now NISA has boosted the figure to 770,000 TBq based on a computer model and newly available data from TEPCO, which owns Fukushima. 鈥淭his is more realistic,鈥� says Morikuni Makino of NISA.
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It is less than Chernobyl, which released 5,200,000 TBq, and is unlikely to alter the risk of cancer deaths compared with the April estimate, says Peter Burns, former CEO of the .
But Burns says it may delay the evacuees鈥� return: 150,000 TBq of the extra radiation is caesium-137, which has a half-life of 30 years.
