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One thing that blows my mind with the Fukushima plant (and presumably others) is that the spent fuel pond is seemingly built above ground. Wouldn't you want thi

by jschrf 16y ago

One thing that blows my mind with the Fukushima plant (and presumably others) is that the spent fuel pond is seemingly built above ground. Wouldn't you want this to be at the very bottom of the reactor building, so that water could collect in it in an emergency situation like in Fukushima where water is pumped in from above? Maybe this is (was) one of the unknowns/unthoughtofs that you mention. As an aside, if no one's seen the excellent Battle for Chernobyl, I highly recommend it. It details the insane clean-up operation that took place after the Chernobyl disaster. It's on Google Video.

gamble 16y ago
The plant is built like that so spent fuel can be lifted out of the reactor and placed directly in the pool using one crane. A more secure spent-fuel pool would have required more elaborate fuel handling, thus a more expensive design. Also, when these plants were built I don't think they anticipated the spent-fuel pools would become long-term storage. There was the assumption that centralized nuclear waste disposal sites would be built and the pools would only store waste until it was safe to transfer.
- jorangreef 16y ago
  This is often the case, a plan for the removal of waste to a disposal site is promised, and then once the plant is built, and the contractors have been paid, nothing happens. New plants are then built, it is said that a disposal plan will be put into effect, and still these plans never materialize.
marze 16y ago
Putting the fuel storage pool on the fifth floor of the reactor does seem questionable, especially given the violence of the explosion at reactor 3. Another "unknown bug" exposed by these events will probably motivate mitigating the risk of hydrogen explosions from hydrogen generated in a partial meltdown. As you can see in the second picture in this link, http://news.ycombinator.com/item?id=2399676 http://news.ycombinator.com/item?id=2399676 the force of the explosion crushed the concrete structure of the adjacent reactor building, and launched enough material into the air that it created holes 60 feet in diameter in the roof of the turbine building when it came down. This was not anticipated; if it were the reactors would have been constructed further apart. The spent fuel rods must be actively cooled for many months after they are removed from the reactor due to heat-generating radioactive daughter products. Since the pools holding them have either boiled away due to the absence of active cooling or drained into the basement due to damage, it is likely these rods overheated. Japanese authorities have mentioned the possibility of "re-criticality", which would be a bad thing, especially in a fuel pond with no containment whatsoever. There will probably be many lessons gained from these events that will be used to reduce risks in other operating reactors and future designs.
bradgessler 16y ago
Link to video mentioned above http://www.youtube.com/watch?v=Wv3a4LXi_qc http://www.youtube.com/watch?v=Wv3a4LXi_qc

by jschrf 16y ago

gamble 16y ago

The plant is built like that so spent fuel can be lifted out of the reactor and placed directly in the pool using one crane. A more secure spent-fuel pool would have required more elaborate fuel handling, thus a more expensive design. Also, when these plants were built I don't think they anticipated the spent-fuel pools would become long-term storage. There was the assumption that centralized nuclear waste disposal sites would be built and the pools would only store waste until it was safe to transfer.

jorangreef 16y ago
This is often the case, a plan for the removal of waste to a disposal site is promised, and then once the plant is built, and the contractors have been paid, nothing happens. New plants are then built, it is said that a disposal plan will be put into effect, and still these plans never materialize.

marze 16y ago

Putting the fuel storage pool on the fifth floor of the reactor does seem questionable, especially given the violence of the explosion at reactor 3. Another "unknown bug" exposed by these events will probably motivate mitigating the risk of hydrogen explosions from hydrogen generated in a partial meltdown. As you can see in the second picture in this link, http://news.ycombinator.com/item?id=2399676 http://news.ycombinator.com/item?id=2399676 the force of the explosion crushed the concrete structure of the adjacent reactor building, and launched enough material into the air that it created holes 60 feet in diameter in the roof of the turbine building when it came down. This was not anticipated; if it were the reactors would have been constructed further apart. The spent fuel rods must be actively cooled for many months after they are removed from the reactor due to heat-generating radioactive daughter products. Since the pools holding them have either boiled away due to the absence of active cooling or drained into the basement due to damage, it is likely these rods overheated. Japanese authorities have mentioned the possibility of "re-criticality", which would be a bad thing, especially in a fuel pond with no containment whatsoever. There will probably be many lessons gained from these events that will be used to reduce risks in other operating reactors and future designs.

bradgessler 16y ago

Link to video mentioned above http://www.youtube.com/watch?v=Wv3a4LXi_qc http://www.youtube.com/watch?v=Wv3a4LXi_qc