Quote Originally Posted by p2501 View Post
Thanks a lot for not giving up on educating people and not losing interest either.

I'm imagining it like this: first, fill up the pressure vessel with sea water/boric acid to keep fuel rods under water. Second, flood the whole containment building with sea water to cool down the outside of the pressure vessel, and keep it flooded. Steam from this step will enter the atmosphere with little effects on the surroundings.

But, why is boric acid so essential in the shutdown process? Why is it "poisoning" the reactor?
Your imagination is pretty close to what they should be doing. My worry is that someone somewhere that doesn't understand the emergency plans are trying to not flood the containment, trying to minimize the amount of water they put in the core, and trying to minimize the amount of steam they release. It's almost like putting a pressure cooker on the stove and trying to let it get as hot as you can with as much water as you can, but try to minimize the release of steam. I get the distinct impression that whomever is making the calls at the top of the Japanese governentment(or the operator), it is purely politically motivated and not in the best interest of the plant. Perhaps they are trying to keep everything inside the reactor vessel and minimize relying on the containment building as the final layer of protection against releasing large amounts of contamination to the environment. I have no solid information to backup my "gut feeling". I'm not completely informed as to why Monday night the fuel was found to again be melting. In my opinion, the only cause for additional core melting would be operator error(but could be due to instrument failures the operators were relying on).

Boron(main component of boric acid) absorbs neutrons. Neutrons are necessary for fissioning of Uranium fuel. It's literally a liquid control rod. Boron is very corrosive and will bond to just about everything in the reactor. Boron literally eats neutrons and in very large quantities. In the hypothetical event that control rods break, melt, or are otherwise not able to be inserted into the reactor boron can be injected. In the case in Japan, all of the rods are inserted(if there is a problem with the control rods Japan isn't talking about it) but boron can be injected as a safety measure to make sure that if the rods are damaged that the core cannot restart itself. Injecting boron into a nuclear reactor effectively makes that core unusable, forever. Yes it "could" be cleaned up and the reactor vessel could be reused. But given the age of the plants and the condition of all of the auxiliary systems for the reactor, there wasn't much chance the reactor would have been restarted anyway. The boron was injected only as a preventative measure to make sure that the core doesn't restart. The boron injection is "just to be on the safe side". The core is effectively "dead" because of the boron, hence it's called "poisoning the reactor".

I'm not sure if boron has ever been injected into a previously operable reactor before, so I'm sure alot of people will want to see how damaging the boric acid will be. The nuclear industry likely will be interested to see the effects boric acid had on the equipment. The nuclear industry is very interested in learning from other's mistakes. Japan is in a situation that is typically only planned for and hopefully never executed. There will be alot of dissecting of the plant going on when it is finally dismantled to see what all was wrong and the effects on the plant.