Japan Doubles Fukushima Radiation Leak Estimate

This image shows the first waters of the tsunami breaching the Fukushima power plant's buildings
Japan has more than doubled its estimate of radiation that escaped from the tsunami-hit Fukushima nuclear plant in the first week after the disaster. Japan's nuclear safety agency also said meltdowns took place in three reactors more quickly than earlier believed.  The assessment comes as an expert panel begins an inquiry into the crisis.

The plant's operator is hoping to shut down the facility by January, although there is concern it may take longer; the plant is still leaking radiation. The 11 March earthquake and the tsunami it generated are now known to have killed more than 15,280 people, while nearly 8,500 remain unaccounted for.

Japan's Nuclear and Industrial Safety Agency (Nisa) now says 770,000 terabecquerels escaped into the atmosphere - more than double its earlier estimate of 370,000 terabecquerels. Although the amount is just 15% of the total released at Chernobyl in Ukraine in 1986 - the world's worst nuclear disaster - it suggests the contamination of the area around the plant is worse than first thought, says the BBC's Roland Buerk in Tokyo.

The safety agency also says that in reactor No 1, molten nuclear fuel dropped to the bottom of the pressure vessel within five hours of the earthquake - 10 hours earlier than initially estimated by operator Tepco.
Nisa also says a meltdown damaged the No 2 reactor after 80 hours, and the No 3 reactor 79 hours after the tsunami knocked out the plant's cooling systems.

The revision, nearly three months into the crisis, is likely to increase criticism in Japan that the plant's operator and the government were too slow to release information, our correspondent says. Meanwhile, Japan's Chief Cabinet Secretary Yukio Edano has said more evacuations are being considered. Going within 20km of the Fukushima plant is forbidden by law, with some towns further away also affected.  But monitoring shows the lie of the land and wind patterns may be causing a build-up of radiation in other areas too.

The findings were released as an independent 10-member expert panel begins an investigation into the causes of the nuclear accident. An investigation by the UN's nuclear watchdog, the IAEA, has already pointed out a key failure - admitted by Japan - to plan for the risk of waves crashing over the sea wall and knocking out the plant's back-up generators.

Even though a major faultline lies just offshore, the sea wall at Fukushima was less than 6m (20ft) high. The height of the tsunami wave was about 14m.