Top nuclear scientists at IAEA are this week examining the raw data from the troubled atomic power plants at Fukushima and discussing changes in the safety features for such reactors even as Japan raised the severity rating of their nuclear crisis to the highest level, seven.

Workers at Japan’s stricken nuclear plant on Thursday pumped nitrogen into a crippled reactor in a bid to prevent a possible explosion, as the government mulled widening an exclusion zone around the site.

Japanese emergency crews have battled to stabilise the crippled Fukushima No 1 atomic power plant that has sparked global fears of a large-scale radiation disaster.