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Tepco engineers use concrete to seal leaks  (Source: TEPCO)
The top five feet of the core's 13 ft-long fuel rods had melted down after being exposed to the air

The Tokyo Electric Power Company (Tepco) has announced that the No. 1 reactor at the Fukushima Daiichi nuclear power plant has suffered a nuclear meltdown.

The Fukushima Daiichi nuclear power plant was first commissioned in 1971 and is located in the Futaba District of Fukushima Prefecture, Japan. On March 11, 2011, a 9.0-magnitude earthquake struck Japan, resulting in the disabling of reactor cooling systems, radiation leaks and an evacuation zone. 

Engineers from Tepco entered the No. 1 reactor for the first time at the end of last week and found that the top five feet of the core's 13 ft-long fuel rods had melted down after being exposed to the air. 

Engineers originally thought only 55 percent of the core was damaged since it was submerged in enough water to keep cool and stable, but after discovering a pool of molten fuel at the bottom of the containment vessel, they now worry that this molten fuel burned a hole at the bottom of the vessel prompting water to leak. 

Tepco recently sealed a leak at the No. 3 reactor after radioactive water had seeped into the ocean. Also, the No. 2 reactor had radioactive water flowing into the ocean in April. According to Greenpeace, "significant amounts" of radioactive material had slipped into the sea. In fact, illegal amounts of iodine and caesium were found in seaweed as far as 40 miles from the Fukushima Daiichi plant. 

In 22 samples of seaweed, ten contained five times the legal limit of iodine 131 and 20 times of caesium 137. This is an issue for several reasons, including the fact that the Japanese household consumes almost 7 lbs of seaweed annually, and fisherman are preparing to harvest this seaweed on May 20. 

Engineers have decided to quit flooding the entire reactor core with water because it might make the leak worse. Currently, there is plenty of water at the bottom of the containment vessel to keep the remaining fuel rods and the melted fuel cool. 

"We will have to revise our plans," said Junichi Matsumoto, Tepco spokesman. "We cannot deny the possibility that a hole in the pressure vessel caused water to leak."


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You don't say
By bug77 on 5/13/2011 7:03:13 PM , Rating: 1
quote:
In 22 samples of seaweed, ten contained five times the legal limit of iodine 131 and 20 times of caesium 137. This is an issue for several reasons, including the fact that the Japanese household consumes almost 7 lbs of seaweed annually


Care to check for how long radioactive iodine and caesium are dangerous? Hint: at most a couple of months.

Yes, this could be an issue if ingested, but I just don't imagine Japanese fishermen scrambling for seaweed anywhere near the Fukushima power plant.




RE: You don't say
By icanhascpu on 5/13/2011 7:30:27 PM , Rating: 5
Its typical alarmist 'journalism'.

Make a scary title to shock people into reading, then provide big numbers like "20 times the legal limit!11" without providing actual information on what that actually means.


RE: You don't say
By Solandri on 5/13/2011 8:34:01 PM , Rating: 2
Cesium-137 has a half life of just over 30 years.

I would still say it's not as serious a problem as Greenpeace is making it out to be, because unless the dispersal pattern is highly unusual, you can just quarantine the area and prohibit seaweed harvesting from the area. Or just harvest it and bury it in a concrete coffin. Cesium levels outside the area should be safe (i.e. lower than what you get from exposure to natural radiation sources, like granite, bananas, and chocolate).

It's a nasty substance to deal with in concentrated form though - its widespread use in chemotherapy has led to a handful of nuclear accidents (non-reactor).
http://en.wikipedia.org/wiki/Caesium-137#Health_ri...


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