Fukushima-Daiichi Spent Fuel Pools Likely Contain Water

Kirk, do you have a reference for this? Not that I don't believe you, but I'd like to post a link to it on my facebook page. Thanks!

If you took a LFTR, picked it up, shook it around, banged it against a rock, set it down for a while and then covered it in water - it too would be a disaster. Thats what a magnitude 9 earthquake is like. The biggest lesson for me in this tragedy is that there is a limit to what ANY structure can withstand. Don't build reactors in known earthquake zones or where there are Tsunami. Also, if you know a reactor is obsolete and old - retire it. I see the freeze plug as basically the feature that positively turns off the fission reaction by draining the reactor into a tank at the bottom whose shape and structure doesn't allow fision to occur. This is fail safe in the sense that you need to cool the plug to keep it closed. Loss of coolant empties the reactor into the tank. The molten salt would still have the decay heat that would make it get hotter over time, and presumably this would normally be treated by pumping it to a heat exchanger with water or steam on the other side. Alternatively, you could make the drain tank large and full of solid salt, which would just melt and dilute the fuel and slow the heat rise. In the event that you cannot get cooling water to it, you might have better luck dumping in more salt. The big benefit I see is that neither the LFTR reactor and tank operate at high pressure unlike boiling water reactors. The salts are molten and do not have any noticable vapour pressure until they are many thousand degrees, so there is no equivalent to the steam venting, hydrogen explosion, helicopter raids etc that we have seen. Instead, substitute other risks: Molten salts are all water soluble, so very important that they be contained. Even though it is not a high pressure environment, recent events have shown that they absolutely will have a containment structure just like modern reactors (before this one of the benefits of the LFTR was that it didn't need a containment structure); There would also be a chemical plant that takes the molten salt and distills off the uranium from the thorium using hydrogen and fluorine. These H2 and F2 are very dangerous gases to handle (but not impossible), but if earthquake ruptured a F bullet, that would instantly kill people. And yes, the LFTR frozen plug was trialled successfully on the LFTR Demo plant. I believe it was the preferred way to shut down the reactor by turning off the cooling water to the plug. If I may rephrase your question: Does anyone know what the decay heat is of a LFTR reactor expressed as a % of its fissioning heat?

I have a (probably dumb) question reqarding visual access to the reactor buildings. Please elaborate for a layman, if you can. Looking at the information coming from the Fukushima incident, one gets the impression as if the crew of the plant cannot see into the buildings. For example, it is said that "the helicopter crew was able see a glimpse of water in the used fuel pool". I'm wondering, would it not be possible to use a remote-controlled miniature helicopter, with a video camera attached, or even a cellphone with a video call on? One would also think the police and the army have remote-controlled crawler robots that could go into the plant. Even further, some of the airport de-icing spray trucks are remote-controlled, surely it would be possible to rig one for radio-controlled operation? Or, are these simple tools used because of a risk of a hydrogen explosion? Then again, one could fly a mini helicopter high above the plant and lower a camera into the building. Or other instruments. This really bewilders me, why it is so difficult to see into the buildings.