These have now been supplemented by an additional rating at the top Level 7, 'a major accident'. Japanese authorities notified the International Atomic Energy Agency of their decision to up the rating: "As a result of re-evaluation, total amount of discharged iodine-131 is estimated at 1.3x1017 becquerels, and caesium-137 is estimated at 6.1x1015 becquerels. Hence the Nuclear and Industrial Safety Agency has concluded that the rating of the accident would be equivalent of Level 7."
Update 14:"There is currently a highly unclear picture of water travel around the site, including how some radionuclides travelled from reactor cores or used fuel ponds to current locations."
http://www.world-nuclear-news.org/RS_Tr ... 03111.html
Trench water under investigation
Meanwhile, water with contamination enough to cause dose rates of up to 1000 millisieverts per hour at the surface has been discovered in a trench for power cables and pipes alongside unit 2's turbine building, which is connected to the bottom of the turbine building via a tunnel. The concrete trench is 76 metres long, four metres high and three metres wide. At each end is a vertical shaft of over 16 metres and the entire system is full with water to within one metre of the top.
Update 13: Workers evacuated as radiation soars
Radioactivity in water at reactor 2 at the quake-damaged Fukushima nuclear plant has reached 10 million times the usual level, company officials say.
Workers trying to cool the reactor core to avoid a meltdown have been evacuated.
Earlier, Japan's nuclear agency said that levels of radioactive iodine in the sea near the plant had risen to 1,850 times the usual level.
The UN's nuclear agency has warned the crisis could go on for months.
It is believed the radiation at Fukushima is coming from one of the reactors, but a specific leak has not been identified.
Leaking water at reactor 2 has been measured at 1,000 millisieverts/hour - 10 million times higher than when the plant is operating normally.
Update 12: A good "Insight to Fukushima engineering challenges".
http://www.world-nuclear-news.org/RS_In ... 03112.html
Update 11: http://www.nature.com/news/2011/110317/ ... 1.168.html
Nature has also learned that initial CTBTO data suggest that a large meltdown at the Fukushima power plant has not yet occurred, although that assessment may change as more data flow in during the coming days.
Update 10: Viewers reporting seeing water being dumped using Helicopters on #3, #4.
Update 9: All 3 reactors have the rods exposed.
* Fukushima Daiichi Unit 1 reactor
o At 6:55AM on March 16, the pressure inside the reactor core was measured at 0.17 MPa. The water level inside the reactor core was measured at 1.8 meters below the top of the fuel rods.
* Fukushima Daiichi Unit 2 reactor
o At 6:55 AM on March 16, the pressure inside the reactor core was measured at 0.043 MPa. The water level inside the reactor core was measured at 1.4 meters below the top of the fuel rods.
* Fukushima Daiichi Unit 3 reactor
o At 8:37AM on March 16, white smoke was observed emanating from the vicinity of the secondary containment building.
o At 9:55AM on March 16, the pressure inside the reactor core was measured at 0.088 MPa. The water level inside the reactor core was measured at 1.9 meters below the top of the fuel rods.
Now you can do some calculations.
o At 10:40AM on March 16, a radiation level of 10 milli sievert per hour was recorded at the main gate of the Fukushima Daiichi Nuclear Power Station.
o At 4:10PM on March 16, a radiation level of 1530 micro sievert per hour was recorded at the main gate of the Fukushima Daiichi Nuclear Power Station.
o For comparison, a human receives 2400 micro sievert per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6900 micro sievert per scan.
Update 8: Japan has raised the maximum radiation dose allowed for nuclear workers, citing the urgent need to prevent a crisis at a tsunami-stricken power plant from worsening.
Update 7: Workers are now back.
Update 6: http://www.bbc.co.uk/news/world-asia-pacific-12755739
A rise in radiation levels at Japan's stricken Fukushima nuclear plant has forced workers to suspend operations, a government spokesman says.
Update 5: http://www.world-nuclear-news.org/RS_Po ... 03111.html
Japanese authorities told the International Atomic Energy Agency (IAEA) that radiation levels at the plant site between units 3 and 4 reached a peak of some 400 millisieverts per hour. "This is a high dose-level value," said the body, "but it is a local value at a single location and at a certain point in time."
Later readings were 11.9 millisieverts per hour, followed six hours later by 0.6 millisieverts, which the IAEA said "indicate the level of radioactivity has been decreasing."
JAIF reported that temperatures in the cooling ponds at units 5 and 6 are increasing, but the reason for this is not yet available.
Update 4 : The Prime Minister said in a live broadcast to the nation that everyone within 20 km should evacuate - and within 30 should stay indoors. The radition is increasing - so there is some breach somewhere ...
Also, there is fire in unit #4.
http://www.cnn.com/video/flashLive/live ... am3&hpt=T1
NHK in English for live coverage.
update 3 : Very bad news. Explosion has occurred within the containment vessel. This means possible rediation leakage.
http://www.msnbc.msn.com/id/42066534/ns ... iapacific/
update 2 : #2 is in serious trouble. There was loss of coolant and some of the rods are presumed broken.
update 1 : Second explosion from the Daichi plant - unit #3 explodes because of Hydrogen.
This thread is to track the environmental impact of the Japanese Nuclear Plants Mishap due to earthquake/Tsunami. Use this thread to also talk about nuclear safety issues etc.
Here is a good news source : http://www.world-nuclear-news.org/RS_Ba ... 03111.html
Here is the official TEPCO news releases : http://www.tepco.co.jp/en/press/corp-co ... dex-e.html