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There is a reason I feel much relieved after reading this. Pretty much everything I've read so far implied that once there is a meltdown, all bets are off. We'l

There is a reason I feel much relieved after reading this. Pretty much everything I've read so far implied that once there is a meltdown, all bets are off. We'll have radioactive material boiling in open air, and all the "good" things that come with it. Which sounded very suspicious to me... I mean, isn't containment designed to prevent exactly that? Once the fuel melts, it just makes a hole on the bottom of the containment and pools on the floor? So for me, the money shot was here: > For that purpose, a large and thick concrete basin is cast under the pressure vessel (the second containment), which is filled with graphite, all inside the third containment. This is the so-called “core catcher”. If the core melts and the pressure vessel bursts (and eventually melts), it will catch the molten fuel and everything else. It is built in such a way that the nuclear fuel will be spread out, so it can cool down. edit: Plus reading about INES, there was a British plant that had 5 (five) level 4 incidents in 25 years, and a partial core meltdown at a French plant. And many more.

illumin8 16y ago
Except that "Fukushima Dai-ichi No.1 Reactor does not have a concrete containment dome. This reactor was built before the now familiar reinforced concrete dome became mandatory for most reactors. Instead, the reactor has a much smaller steel containment vessel around the reactor vessel." This was from a Slashdot comment, so I trust it about equally to a newly minted blog with only a single post: http://slashdot.org/comments.pl?sid=2033910&cid=35463272 http://slashdot.org/comments.pl?sid=2033910&cid=35463272 Someone with more knowledge of nuclear power history could surely cross reference the dates here for us and confirm/deny the existence of the 3rd containment layer: Fukushima Daiichi Unit 1 - 439 MWe BWR, 1971 - Automatically shut down - Water level decreasing - Pressure release implemented - Explosion observed - Containment believed intact - Seawater injection has started - Radiation levels did not rise after explosion Unit 2 - 760 MWe BWR, 1974 - Automatically shut down - Water level lower but steady - Preparations for pressure release Unit 3 - 760 MWe BWR, 1976 - Automatically shut down - Preparations for pressure release Unit 4 - 760 MWe BWR, 1978 - Shut for periodic inspection Unit 5 - 760 MWe BWR, 1978 - Shut for periodic inspection Unit 6 - 1067 MWe BWR, 1979 - Shut for periodic inspection

illumin8 16y ago

Except that "Fukushima Dai-ichi No.1 Reactor does not have a concrete containment dome. This reactor was built before the now familiar reinforced concrete dome became mandatory for most reactors. Instead, the reactor has a much smaller steel containment vessel around the reactor vessel." This was from a Slashdot comment, so I trust it about equally to a newly minted blog with only a single post: http://slashdot.org/comments.pl?sid=2033910&cid=35463272 http://slashdot.org/comments.pl?sid=2033910&cid=35463272 Someone with more knowledge of nuclear power history could surely cross reference the dates here for us and confirm/deny the existence of the 3rd containment layer: Fukushima Daiichi Unit 1 - 439 MWe BWR, 1971 - Automatically shut down - Water level decreasing - Pressure release implemented - Explosion observed - Containment believed intact - Seawater injection has started - Radiation levels did not rise after explosion Unit 2 - 760 MWe BWR, 1974 - Automatically shut down - Water level lower but steady - Preparations for pressure release Unit 3 - 760 MWe BWR, 1976 - Automatically shut down - Preparations for pressure release Unit 4 - 760 MWe BWR, 1978 - Shut for periodic inspection Unit 5 - 760 MWe BWR, 1978 - Shut for periodic inspection Unit 6 - 1067 MWe BWR, 1979 - Shut for periodic inspection