TEPCO just released data on radioactivity in sea water that shows that the amount of radioactivity entering sea water is way up from levels reported 2 weeks ago. Moreover, short lived I-131 levels continue to stay high at levels that are very hard to explain if it is not being produced by continued criticality of some part of the apparently melted down core. TEPCO continues to pour water over the reactor vessel and it continues to leak away. It's clear that some of that water continues to flow into the ocean.
After temporary declines, I-131 levels in entering the ocean near Fukushima unit 2 returned to levels seen one month ago. Moreover, the ratio of I to Cs has gone up, not down. Since I-131 has a half life of 8 days, levels should have dropped by almost 4 half lives, over a factor of ten by radioactive decay alone. Continued high levels of I-131 are an indicator of possible continued criticality of part of the damaged core. Elevated levels of I-135 with a half life of 8 hours would be proof positive of criticality but it has not ever been reported by TEPCO. (diarist's figure notation)
Radioactive materials in the ocean near the Fukushima Daiichi nuclear power plant rose to 3,300 times the legal limit on Sunday.
Tokyo Electric Power Company says it measured 200 becquerels of cesium-134 per cubic centimeter on Sunday morning near the water intake of the No. 3 reactor. The level was higher than on the previous day, when it was 2,300 times the legal limit.
220 becquerels of cesium-137 per cubic centimeter was also detected. At 2,400 times the legal limit, the level exceeded the one found the day before
TEPCO now admits that water from unit 3 has flowed into the ocean and has released a plan to remove water from the reactor vessel.
Tokyo Electric Power Company, or TEPCO, estimates that there is about 22,000 tons of highly radioactive water in thereactor's turbine building and in a connecting tunnel.
The utility says the water in the basement of the turbine building was about 1.4 meters high as of Monday morning, a rise of more than 20 centimeters over the past 2 weeks. Part of the water leaked into the sea last week.
TEPCO now admits that units 1, 2 and 3 may be all leaking after have all melt downs. They admit that the some of the water is entering the ocean. They plan to change their approach to cooling the damaged reactors but they have not yet figured out how to do it.
It says it is now considering pumping water out of the containment vessels and circulating it back into the reactors after chilling it with heat exchangers.
Another method under study is pumping water from the basement and sending it back to the reactors after radioactive substances have been removed.
Never the less, TEPCO claims they will achieve a cold shut down in 6 to 9 months. TEPCO has not explained how it will possible to shut down a melted down core. Because the reactor units are so close to sea level in a humid environment, if the melted "corium" has penetrated the reactor vessel, the corium would be involved with groundwater continuously flowing to the ocean. Even a concrete sarcophagus may not be able to stop the release of radioactivity to the ocean. Moreover, stopping intermittent local criticality events may be very difficult in this environment.
Sirocco, on behalf of the IAEA, has modeled the transport of dissolved and particulate radionuclides in sea water off the coast from Fukushima.
Much of the radioactivity released appears to have moved north then been transported offshore by swirling currents.
The sudden recent increase in cesium isotopes north of Fukushima may indicate that some cesium is being transported in colloidal or adsorbed form while iodine is fully dissolved. The spike in cesium versus iodine may show the arrival of the cesium attached in some form to a clay mineral or other solid material.
Updated by FishOutofWater at Mon May 16, 2011 at 08:44 PM EDT
Seaweed within 40 miles has been found contaminated by Greenpeace.
http://www.presstv.ir/...
Initial tests of 22 seaweed samples collected by Greenpeace's Rainbow Warrior flagship at distances up to 65 kilometers from the plant "registered significantly high levels of radioactive contamination," the environmental active group reported on Thursday.
"As both TEPCO's sediment samples and our own preliminary research shows, radioactive contamination is accumulating in the marine ecosystem that provides Japan with a quarter of its seafood, yet the authorities are still doing the very little to protect public health," warned Ike Teuling, Greenpeace radiation expert.
"Contaminated seaweed could become a threat as fishermen along the coast will begin harvesting the seaweed to sell for public consumption in the coming weeks," Greespeace added.
The group has also sent samples of fish, seawater, and seaweed collected outside of Japan's territorial waters and the Fukushima coast to independent laboratories for further analysis and will report the results in coming days.