Quetzalcoatl.Kanjirou said:
@BBCBreaking via Twitter said:
1009: "This is starting to look a lot like Chernobyl" Walt Patterson, an associate fellow with Chatham House, has told the BBC after seeing pictures of the explosion at the Fukushima-Daiichi nuclear plant. "The nuclear agency says that they have detected caesium and iodine outside the unit, which certainly indicates fuel melting at the very least," he says. "Once you have melting fuel coming into contact with water, that would almost certainly be the cause of the explosion."
Dasva, thoughts? Does that really indicate what he claims it does? Isn't this the sort of thing you said could re-ignite reactions?
It could. I'd wait though.
And yes fuel does cause it can cause water to seperate into it's compenent gasses in fact it's normalish in a reactor but usually keep things pressurized and and disolved in the water. And usually lower temp fuel plates the heat can do it too.
And no it probably wouldn't. Ok some basics. It's not an explosion or anything that starts the reaction. It is always going on. Right now most of it is from the decay of fission products which is also where most the heat is coming from. But even after it's been shutdown forever and a day there will still be source neutrons from spontaneous fission and such. In order to achieve a criticality on average each fission event needs to create on average 1 neutron that will go on to create another fission. Average number of neutrons released per fission event is mainly dependent fuel type. Now how many go on is dependent on alot of things alot of which we control in order to control power. Basically the neutrons will usually get absorbed by other stuff. Or wont have enough energy to split the fuel (not sure which kind this reactor uses). That's actually the point of the control rods. They absorb neutrons super awesome lowering how many go on to be absorbed greatly. Indeed the spacing between the fuel and loaded poisons and such also kinda limit it. The loss of water also helps this as it is also often used to reflect the neutrons back to the fuel and now air in that space doesn't work as good. If they are using enriched fuel the water also is used to slow them down giving a greater chance of absorption. An explosion could help seperate fuel even more.
Or tldr pretty much in the end closeness of fuel material that restarts it. Which is why nuclear explosions need an actual implossive event to cause an increase in rate of reactions fast enough to do that. And between the rods in there and poisons loaded in the fuel itself and distance kept between it would general require stuff melting back together. It's actually designed like this with stuff like this in mind
