Level 3 Fukushima

(Reuters) - Japan will raise the severity rating of a recent toxic water leak at the destroyed Fukushima nuclear plant to level 3, or "serious incident", on an international scale for radiological releases, underlining the deepening sense of crisis at the site.

Contaminated water with dangerously high levels of radiation is leaking from a storage tank at Fukushima, the plant's operator said on Tuesday, the most serious setback to date for the clean up of the worst nuclear accident since Chernobyl.

Japan's Nuclear Regulation Authority (NRA) assessed that the leak merits a level 3 rating, classifying it as a "serious incident" on the INES scale, according to a document posted on the agency's website on Wednesday.

The leak had previously been assigned a level 1 "anomaly" rating, but the increase to level 3 is scheduled for formal adoption by the authority's commissioners later on Wednesday after a meeting that is currently under way, a spokesman for the agency told Reuters by phone.

"Judging from the amount and the density of the radiation in the contaminated water that leaked ... a level 3 assessment is appropriate," according to the document, which is one of several discussion points at the regular weekly meeting of NRA commissioners being held on Wednesday.

This marks the first time Japan has issued an INES rating for Fukushima since the meltdowns in March 2011, following a massive earthquake and tsunami. Fukushima was assigned the highest rating of 7 after it was hit by explosions in the wake of a loss of power and cooling.

Each one-step increase on the INES scale represents a 10 times increase in severity, according to a factsheet on the website of the International Atomic Energy Agency.

(Reporting by Kentaro Hamada and James Topham; Writing by Aaron Sheldrick; Editing by Edmund Klamann)

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21 August 2013

Japan nuclear agency upgrades Fukushima alert level

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Rupert Wingfield-Hayes reports that the change in severity level is regarded as "significant"

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Japan's nuclear agency has upgraded the severity level of a radioactive water leak at the Fukushima plant from one to three on an international scale. Highly radioactive water was found to be leaking from a storage tank into the ground at the plant on Monday. It was first classified as a level one incident on the International Nuclear and Radiological Event Scale (Ines). But Japan's Nuclear Regulation Authority proposes elevating it to level three on the seven-point scale. Japanese reports say it is a provisional move that had to be confirmed with the IAEA, the UN's nuclear agency. This week is the first time that Japan has declared an event on the Ines scale since the 2011 earthquake and tsunami. The move was announced in a document on the agency's website and was subsequently approved at a weekly meeting of the regulatory body.Shares of plant operator Tokyo Electric Power Company (Tepco) fell as much as 13% to 537 yen as investors worried about the impact of the development.

'Five-year dose'

This hand out picture taken by Tokyo Electric Power Co (TEPCO) on 19 August 2013 shows contaminated water which leaked from a water tank at Fukushima nuclear power plant Workers discovered the water was leaking from a tank on Monday

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The March 2011 tsunami knocked out cooling systems to the reactors at the plant, three of which melted down. Water is now being pumped in to cool the reactors but this means that a large amount of contaminated water has to be stored on site. this one is being seen as the most serious to date, because of the volume - 300 tonnes of radioactive water, according to Tepco - and high levels of radioactivity in the water.

A puddle of the contaminated water was emitting 100 millisieverts an hour of radiation, Kyodo news agency said earlier this week.

Masayuki Ono, general manager of Tepco, told Reuters news agency: "One hundred millisieverts per hour is equivalent to the limit for accumulated exposure over five years for nuclear workers; so it can be said that we found a radiation level strong enough to give someone a five-year dose of radiation within one hour."

Teams of workers at the plant have surrounded the leaking tank with sandbags and have been attempting to suck up large puddles of radioactive water.

But, reports the BBC's Rupert Wingfield-Hayes in Tokyo, it is a difficult and dangerous job. The water is so radioactive that teams must be constantly rotated and it is clear that most of the toxic water has already disappeared into the ground.

Under the Ines, events have seven categories starting with Level 0 ("without safety significance") and Levels 1-3 denoting "incidents" while Levels 4-7 denote "accidents".

The triple meltdown at Fukushima two years ago was classed as a level 7 incident.

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