Výběr zpráv ze sítě NucNet - 16. týden 2011

Slight Fall In Radioactive Water Level At Fukushima-Daiichi

Tokyo Electric Power Company (Tepco) says the level of highly radioactive water at the Fukushima-Daiichi nuclear power plant has fallen since work started on 19 April 2011 to remove it from the unit 2 reactor complex.

Tepco said the level of contaminated water in a tunnel linked to unit 2 was one centimetre lower than the previous day as of 07:00 local time (midnight central European time) on 20 April 2011.

That amounts to a reduction of 210 tonnes of the water in the tunnel, pumped out at a rate of 10 tonnes per hour, Tepco said.

Tepco is aiming to remove 25,000 tonnes of the contaminated water from the unit 2 turbine building basement and connecting tunnel to a nearby processing facility.

The contaminated water needs to be moved because there is a risk it might leak into cable trenches and pits outside the unit’s controlled zone and from there flow into the sea.

Contaminated water has also been found in the turbine hall basements of units 1 and 3, although its level of radioactivity is much lower than the water at unit 2.

The total amount of water to be removed is estimated at more than 60,000 tonnes, the International Atomic Energy Agency said.

Tepco will monitor the current pumping rate for 10 days or more and then add more pumps, in an effort to move 10,000 tonnes of the highly radioactive water by mid-May.

With the cooling systems at units 1, 2 and 3 still out of order, Tepco has been pumping fresh water into the reactor pressure vessels and spraying the spent fuel ponds at units 1, 2, 3 and 4 in an effort to stop nuclear fuel overheating.

While this has so far prevented a dangerous over-heating of the reactor cores and spent fuel ponds, it has also created a large quantity of contaminated water that Tepco needs to remove before other work can progress.

Zdroj: NucNet

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