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The Daiichi power plant shut down automatically after the 9.0-magnitude earthquake hit (recently updated from 8.9), but the cores of its four [there are actually six in total, but three had been shut down] reactors still require cooling to prevent a meltdown. The cooling is normally provided by water that is pumped into the core using electricity. The earthquake cut off electricity needed to drive water pumps, and then backup diesel generators failed, likely as the result of the tsunami triggered by the earthquake. Although details are difficult to confirm, it appears that another cooling system that uses batteries and steam-driven pumps also failed, and a heat exchange system that removes heat from the water coolant around the reactor seemed to be damaged, says Andrew Kadak, a research affiliate at MIT. A key next step is to repair or replace the heat exchanger system to provide a way to remove heat from the seawater. This will eliminate the need to vent steam, which contains radioactive materials, into the atmosphere.

The reactors at the nuclear plant, built in the early 1970s, rely on active cooling systems that require electricity. Newer plant designs would lessen or eliminate the need for active cooling, making use of natural convection or a "gravity feed" system to cool reactors in the event of an emergency. "We shouldn't lose sight of the enormity of the earthquake and flood," he says. "Nuclear power plants are designed for earthquakes and hurricanes, and in some places tsunamis. But these were unbelievably large." www.technologyreview.com

Something that is an additional factor of concern is that the building that units 1-4 are are identical to units 1-2 at Hamaoka. Those where shut down because Chubu decided the retrofits were too expensive. It was cheaper to build a new higher power NPP, it was easily in the double digit billions. Some of the things mentioned in the article that I now can't find were roof braces to dampen upper building swaying. Chubu cited the tall skinny upper building and the offset reactor well in that upper building as being very prone to lots of lateral swaying in a quake.

NEW CTBTO Takasaski radioisotope report www.cpdnp.jp

@Tenzing good catch! I think we can start building a list of known potential factors to see where we get on this.

@dean, yes, this info has the potential to make a big impact on things.

@Nancy Nothing personal, but here is one sentence from that report "TEPCO said that as 10 to 70 millisieverts per hour were detected in areas where workers would be expected to spend prolonged periods of time inside of the No. 1 reactor, restoration work is possible." Is it possible or impossible? In the business, we talk about "contact Readings" and "General Area Readings". This article gives a range of 10mSV/hr (totallyy workable with controls) to 70 (I think supposed to be 700) mSv/hr, pretty much unworkable if have to stay there for any length of time. My point is the info we are getting is so distilled (in english anyways) and so confused (to me) in Japonese as to be useless to evaluate. We simply must rely on the actual data provided by TEPCO because at least we are looking at the numbers they are looking at. "higher than expected radiation inside #1 may hamper work efforts " may be true, but the info is not sufficient to really believe that, I've worked in 10-50 mSv/hr succesfully in the past, and spot areas of 100 mSv/hr (not 700 mSv/hr though). It requires rigorous monitoring and control of work, nothing more.

@RBeaner just passing on the news article, made no claims about it. :-)

@RBeaner of course. Everything works fine until it stops working fine. The big factor is what happens when it stops working as intended. Yes, I really need more coffee this morning.

The new Takasaki data indicates that the iodine/cesium ratio has increased. This means new fission between April 24 - May 4. The last data point is 4 days before the May 8 "high-density" radioactivity release.

@RBeaner the article even explained that. Sounded like they were going to use some lead shielding to allow them to be in some of the areas with higher readings without getting large doses.

@LM A while back they were showing detailed pics (video) of the installed (HEPA) air filtration system. On every one of them were these white herculite (plastic like) things about 2 ft by 3 ft, those were what is called lead bats. They are filled with lead wool for shielding purposes (gamma radiation). It shows they are thinking a bit at this point. Those HEPA filters WILL become highly radioactive (and emit high radiation) during and after use, but not before. They planned for those high Radiation readings at the start, not later. It is a small thing, but shows they are (at least) becoming pro-active vice re-active)

@RBeaner I get the impression from a few different things that the technicians and engineers are more able to "run the show" at least as far as the work at the plant rather than the corporate office trying to run things based on the wrong reasons. There was a mention a few weeks ago that govt. officials would have a larger role. The interview of one of the main engineers explained how he had to really prove his case to get TEPCO to approve his plan to build some temporary tsunami wall improvements. He felt it was critical to protect that area around 3 and 4 from another tsunami wave but had to jump through hoops to get the corporate office to approve. The suspected dynamic of TEPCO corporate office thinking one way and the actual technical people another seems to be playing out.

@Nancy We used shielding all the time to reduce radiation exposure. It does NOT reduce radioactivity exposure. They put the ventilation in to reduce the radioactivity in the air (like dust) so as to reduce possible INTERNAL exposure. Not general radiation exposure (though it helps a little). They went in with SCBA (Self Contained Breathing Apparatus) innitially. They are nearly 100% effective against airborne contaminates, but they want to use respiraters (gas masks). The gas mask is easier to use, but "only" drops the radioactivity by a factor of 1000. Hence the need for air filtration.

@Bobby1 Come on, where is your source? We are trying to damp down baseless speculation at this point. "Expect elevated levels of Iodine-131 to enter the west coast tomorrow, from Vancouver BC to Los Angeles, expanding into the Rockies and northern plains by Wednesday". There have been no significant, long term depositions of radioactive material in the US. IF things continue in Japan the way they are going now, There WILL be no significant depositions in the US.

@RBeaner "Groundless rumors"? Do you work for the Japanese government? Read my posts before that.

@LM The air monitoring is still in effect by EPA oaspub.epa.gov and Berkely is still doing monitoring www.nuc.berkeley.edu and both were in steady decline. I admit, I am still concerned about fish, eventually, but not right now. Ijust saw your latest post Show me the source for your new elevated I-131 level please.

@Bobby1 And there is no safe car speed. All life has risks. I am not claiming there is a safe dose, just that it must be taken into account with daily risks. Your attitude may have been appropriate before a nuclear accident and also after, but we are in the midst of a nuclear accident, and IMHO more reasonable approaches must prevail.

@RBeaner The NRC has declared a state of emergency.

@RBeaner www.eenews.net