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As far as I was aware the reactors at Fukushima shut down correctly as soon as the earth quake occurred. While the crisis definitely continued I think the repor
by hygap 13y ago
As far as I was aware the reactors at Fukushima shut down correctly as soon as the earth quake occurred. While the crisis definitely continued I think the reporters portrayal of the reasoning is somewhat misleading. As it insinuates it was the fuel rods inability to control the reaction was the problem, rather than the cooling system's inability to deal with the excess heat generated post shut down.
"When a uranium reactor overheats and the fuel rods can’t contain the chain reaction, as happened at Fukushima, the crisis continues."
- mnw21cam 13y agoYes, the reactor shut down correctly. However, in a working uranium reactor, there will be large quantities of fission products that are also radioactive and are therefore spontaneously decaying in a long chain towards stable isotopes. Some of the fission products are quite short-lived, so for quite some time after the reactor is shut down they will be generating a lot of heat. What happened at Fukushima is that the cooling system that needs to keep running for weeks after a shutdown broke. This caused the water in the reaction vessel to boil, uncovering the tops of the fuel rods, which then got so hot that they broke steam into constituent hydrogen and oxygen (which caused the subsequent explosions) and they cracked open, releasing some nasty isotopes into the coolant water. The coolant water with nasties in is what has been leaking out into the environment.
- hygap 13y agoI agree, well expanded. The mechanism seems to be a lot safer in a liquid thorium reactor where the thorium drains away into a safety chamber in the event of a similar disaster. I just wanted to point out the events the article portrays are incorrect and the writer could have conveyed this message without insinuating there was a meltdown due to the failure of the (wait he says fuel rods not control rods....) O well.
- mnw21cam 13y agoAnother advantage with a liquid fuel is that you can do a continuous reprocessing cycle (pump the fuel through a chemical plant) to remove nasties from the system. With solid fuel pellets all you can do is hope that the pellet doesn't crack and let the nasties out. Having no pressure vessel with ultra-superheated water and a 1000-times-the-size containment building around it in case it all suddenly turns into steam helps too.
- soperj 13y agoThere has been some articles indicating that the containment block might have already been compromised prior to the tsunami.
- skelsey 13y agoCan you provide a link?