Fukushima disaster raised to level-7 on Ines scale

• 13 years ago (2011-04-13)
• Junior Isles

Asia 892 Nuclear 659

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The Nuclear Safety Commission of Japan has decided to raise the severity rating of the Fukushima nuclear crisis to the highest level, seven.

The decision reflects the total release of radiation at the damaged Fukushima Daiichi power plant, which is ongoing, though at a decreasing rate according to Japanese Prime Minister Naoto Kan.

The Tokyo Electric Power Company (Tepco), the operator of the plant, would soon provide a schedule for getting it fully under control, he said at a news conference. "Step-by-step, the reactors in the Fukushima Daiichi power plant are moving toward stability," he said.

The Chernobyl disaster, where 10 times as much radiation was emitted, is the only previous disaster to reach level seven. There have been no fatalities resulting from the leaks at Fukushima, and risks to human health are currently thought to be low.

The level seven signifies a "major accident" with "wider consequences" than the previous level, officials say. Though, the current level is reported to be only a preliminary assessment, requiring further technical evaluation by specialists.

"We have upgraded the severity level to seven as the impact of radiation leaks has been widespread from the air, vegetables, tap water and the ocean," said Minoru Oogoda of Japan's Nuclear and Industrial Safety Agency (Nisa), the government's nuclear watchdog.

Reporting the commission's decision, the IAEA said previous level five ratings had been provided separately for accidents at Reactors 1, 2 and 3 but had now been combined as a single accident. Another affected unit, Reactor 4, has retained its level three rating, it said.

One official from Tepco said that radiation leaks had not stopped completely and could eventually exceed those at Chernobyl. Though a nuclear safety expert reassured media that, "In terms of volume of radioactive materials released, our estimate shows it is about 10 per cent of what was released by Chernobyl."

The decision to raise the threat level was made after radiation of a total up to 630 000 terabecquerels had been estimated at the stricken plant. That would classify the crisis at level seven on the International Nuclear and Radiological Event Scale (Ines).

It was not clear when that level had been reached. The level has subsequently dropped to less than one terabecquerel an hour, reports said.

Officials have warned it may be up to several months before the situation at the nuclear facility is brought fully under control.