JAPAN HAS MORE than doubled its initial estimate for the level of radiation leaked from the stricken Fukushima Dai-ichi power plant in the north-east of the country.

The AFP reports that Japan’s Nuclear and Industrial Safety Agency (NISA) revised the initial estimate upwards ahead of today’s launch of an official probe into the causes of the nuclear crisis.

Japanese officials have emphasised that most of the radiation leaked by the plant in the early days of the crisis was blown out over the sea.

Last week, an IAEA group released the preliminary report of its fact-finding mission to Japan. It criticised Japan for underestimating the potential tsunami risk to the Fukushima nuclear plant, but said the emergency response to the crisis had been exemplary.

More recently, Japanese officials confirmed that two of the plant’s workers had exceeded radiation exposure limits set by the government in the wake of the disaster. However, neither is showing any immediate health problems.

Japan is facing a potential energy crisis over the summer due to the knock-on effects of the Hamaoka nuclear plant’s temporary closure and the disablement of the Fukushima station.

The Japanese government and the Fukushima plant’s operators, TEPCO, have been accused by local residents of failing to release adequate and timely information about the ongoing crisis. About 80,000 people were evacuated from the area surrounding the plant.

TEPCO has announced it intends to bring the Fukushima plant to a complete ‘cold shutdown’ by the end of this year, although some experts say this timeline is too optimistic.

Over the weekend, TEPCO said it was moving another 1,500 tonnes of radioactive water from the plant into temporary storage in order to prevent the water leaking into the ground or the sea. Over 100,000 tonnes of radioactive water are pooled beneath the plant.

- Additional reporting by the AP