[Emergency System Schematic, Two identical, full capacity systems termed Div. 1, Div. 2, either will perform the required safety functions. The Japanese HPCS pumps were driven by steam-turbines, not a dedicated diesel generator set as depicted.]
The following excellent information is taken from this website: http://klickitat.org/nucleartourist/fukushima.htm
This explains where the hydrogen gas came from, to relieve pressure within the reactor system, we were previously told the operators were venting to the containment. This, a poor translation from the Japanese language. This discussion clears that up, and that the gases in the primary containment were vented to the reactor building, secondary containment. Too bad they could not vent to the main plant vent through the filters provided. This would have prevented the hydrogen excursions destroying the upper structures of the reactor buildings.
Time will tell.
"The Fukushima event is slowly building to become the most significant event in the history of nuclear power. During the next couple of days, I will be working to update this page to cover all aspects of this event and also to relate this event to US reactors. Please stop back when you can."
At this point the event has been classified as an INES Level 5 accident. Although antinuclear proponents, e.g. Greenpeace, disagree, neither the IAEA nor the US Nuclear Regulatory Commission currently disagree with Japan's assessment. [Such a designation is rather academic]
As of April 2, radiation levels at locations around the Fukushima plant were trending downward. US Energy Secretary Chu estimated that 70% of the Unit 1 and 33% of the Unit 2 core had melted NY Times, April 1). The Japanese agencies have also reported concrete cracks that may provide at least one path for radioactive releases to the sea (washington Post, April 2). [DOE Sect'y. Chu hasn't a clue as to what's going on in the nuclear field]
An excellent Nuclear Crisis in Japan seminar presentation was recently provided by Dr. Alan Hanson on March 21 at the Stanford University's Freeman Spogli Institute for International Studies. It should be noted that this presentation presents an analysis based on information received to date. [Click on URL cited above]
