APR: your source for nuclear news and analysis since April 16, 2010

Saturday, March 12, 2011

Fukushima Daiichi 1: Accident

Nuclear Accident Likely at Fukushima Daiichi 1.

-Explosion occurred as another aftershock hit the site at 3:36 PM local time

-Radiation Disaster measures declared 5 PM local

-Injection (probable core flood) of seawater and boric acid begun 8:20 PM local

-Boric acid, containing Boron, is a material that tends to slow nuclear fission rates by absorbing neutrons

-TEPCO officials have reported that the primary coolant system is intact

-The containment (secondary boundary) has been seriously damaged by the explosion, reportedly a hydrogen explosion as surmised here on this blog at 6 AM this morning

-The source of the hydrogen is not exactly known, but could come from both radiolytic dissociation of the primary coolant (which is water) and from metal-water reactions if some of the fuel rods have melted

-TEPCO has stated that it is possible that about 1.7 meters of the fuel rods in this plant (which are a total of 4.5 meters long) were exposed to air when water level in the reactor dropped during the period of total electrical generation outage on site (failure of EDG's as reported yesterday.) If this is true, fuel damage is very likely and there may have been, or may even now be, a core melt in progress

-Releases of fission product gases have been detected, also strongly hinting at fuel element failure

-As reported here yesterday several times, the use of seawater in the plant proves that the plant operators have run out of primary coolant grade water and secondary grade water at the site

-Fukushima Daiichi 1 is the oldest plant affected by the earthquake.

We will have MUCH more data today, this evening and tonight as the situation develops.


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