I am a structural engineer at a plant, just started here about a year ago.
While I have never designed a containment building, I am aware of some of the design inputs.
Basically, every imaginable force that could be a issue is considered. And they are designed with a lot of margin.
I am not sure what you are asking though. Are you asking if they are designed for a tsunami? I am not sure, I know the plan I work at is not, but I work in the midwest so that is not one of the design criterias.
But they are designed for a certain internal pressure, wind, earthquake, collision/impact, dead & live loads, snow. The one I work at is designed in excess of the 1000 yr flood.
Just so all of you know, the media is very clueless about what they are talking about. They are making this issue over there sound much worse than it is in respect to the nuc plant. The plant will never operate again, but they are designed such that in an accident condition to safely shut down with the health and safety of the public as the #1 priority. This is the case in the US atleast.
The level of radio active release was very small (comparitive to getting a couple of x-rays). But, media hype gets peoples to tune in, so they are making it sound worse to get more viewers. And to the reporters defense, they are uneducated about the nuclear power, so they do not know better.
delagina, your sketch looks like a hyperbolic cooling tower, which is not the reactor building.
I did some work on a project adding security fencing to the roof of a reactor building here in the US. I don't know what went into the original building design, but for the fence they wanted every anchor bolt engraved with a serial number that could be tied back to a database of manufacture specs! Given that, I would think every last detail of the reactor building would have been considered.
I've worked on designed Mark I, II and III BWR (GE) containments structures. I've never designed one myself and besides, there is always a team involved as they are complicated structures with multiple levels of review. I was on the projects well after the containment was done. The last BWR designed by my old firm was done in the early 70's.
However, I can verify that they are designed for an incredible combination of very conservative loads, not only the ones DWHA mentions but also tornado, a full guillotine main steam pipe break as well as the dynamic loads resulting from the pipe break incidents and many more.
From what I can tell, and it's still hard to get information, the containment is still fine. However, due to earthquake knocking out the primary and secondary cooling systems and the Tsunami knocking out the rest, the operators can't cool the core. To relieve the high heat and pressures developed and to make room for the cooling water, they vented gas into the secondary containment, which is a lighter structure designed mostly as a gas barrier. In there, hydrogen gas, a byproduct of the vented gas, ignited and exploded. The main problem isn't these explosions, it's that they can't cool the core.
But don't get me wrong, this is very scary.
No, meltdown is an uncontrolled condition that couldn't have loads nor temperatures defined. Plus, I don't think there are any materials that could withstand the temperatures of an uncontrolled reaction (4000 degrees F?).
It's not like an nuclear blast, as they are made to release energy in a sudden manner, but it does release a large amount of energy. But there are many, many safeguards in place to keep meltdown from occuring. While in the Japanese reactors several have been made inoperational, they still have some tricks up their sleeves. Let's hope they can slow and stop this reaction.
Even optimistically, it's unlikely these reactors will ever operate again. And they'll have a huge nasty mess to clean up.
Watching cable "news" I'm not surprised that viewers are scared, they are milking the scare for all it's worth.
In any other type of power station, the emphasis is on producing steam to drive the turbine generators. Although that is why we build nukes, the emphasis changes, it is all about cooling the reactor. Some heat is extracted from the cooling water to run the turbines, the rest is cooled in the hyperbolic cooling towers in a closed system, or released in an open (once through) system. The cooling is run from the electrical grid when the unit is in shutdown. In this case, the earthquake broke the grid and the units went on to their batteries.When they ran out, they went to a system where diesels spray fresh water onto the reactor to cool it, that stopped after a while, reason unknown. Now they are using fire trucks to pour sea water into the building; this produces steam that must be released.
The units were shut down, but they were still hot, and the fuel still radiates particles even though the reaction has stopped, this radiation still emits some heat, enough to melt the metal if it is not cooled. eventually, it will get hot enough to burn/melt the concrete base, hence The China Syndrome". They don't explode.
Michael.
Timing has a lot to do with the outcome of a rain dance.
My understanding is that the emergency diesel generators did not go down for some unknown reason. Either the title wave took them out or the wave took out the diesel supply tanks.
