are all japans skyscrapers specifically designed to withstand quakes? or just the posh ones?

All the new ones are built specifically to withstand them. The older ones have had alterations (like shock absorbers) to reduce risk of earthquake damage.

The newer ones (prob all of them) now use a system which is a bit like building it like a cupboards with casters instead of feet. The casters fit into metal dish shaped things which allow the base to slide around under the building while the building keeps relatively stable.

That is true although what magnitude of earthquake I'm not sure.

Looks like the nuclear reactors were built to withstand a 7 magnitude quake....from The Wall Street Journal:

To be fair the reactor didn't bat an eye at the earthquake, they behaved exactly as they were designed to do.
It was the tsunami taking out the back up generators used for emergency cooling that's caused the problems.

Aye, looks like it. Mind you can you actually build anything that would withstand a magnitude 9 earthquake?

You probably could but the costs would be horrendous.

Well, nuclear reactors aren't cheap anyway. However it's always a simple risk/cost analysis - what are the chances of it happening, how much would it cost to mitigate that risk?

The bit that does p!ss me off slightly is that there are suddenly people saying Fukushiima should cause us to reconsider any plans to build nuclear power stations in the UK. Er... when did we last have an earthquake of any significant effect at all, and how do you get a giant tidal wave out of the Irish sea? We are not in Japan, we don't have Japan's problems or resource profile. We can assess whether we want/need nuclear power or whether we'd be better off with wind/wave energy or 'clean coal' or the like, but let's do it in a reasonably rational way, eh?

Jon

There was something developed several years ago - the foundations are slip blocks with motion dampers.

There were supposed to withstand a magnitude 9 quake, simulated at least.

There are some issues that need addressing. Why wasn't a failsafe built in from scratch that if the power failed overall then the control rods would be automatically released so that they fall into the reactor shutting it off. So if some other method had interrupted power then the reactor would have shut down even if all the technicians had been killed. That applies even here. Though if solved then it should not be an issue.

The other consideration is location of the reactors. While I acknowledge that they need access to lots of water they should be further from the cost especially in a tsunami risk zone. With water piped from coast to the plant, which is in a safer location.

This is exactly what did work.

The problem is that once the control rods are in there, there is still an issue of residual heat from the decay of the other elements (iodine, caesium, etc...)

They have to cool the rods with water until the residual decay and heat has dissipated. The part that failed was the electirc water pump, and the back up diesel water pump and the back up of the back up diesel water pump.

They did but they are very hot so although no new heat is being generated uou need to cool them off e.g. if you start to boil a kettle and then switch it off the water is still hot inside the kettle

If the cooling system had not been knocked out by the Tsunami then all would ahve been ok within a couple of days or so

Which still brings me to the problem of why did they build it on the coast. I know that they need huge quantities of water to cool but why not build a huge bore water pipe bringing the water from the coast? That would have eliminated the tsunami risk. It might have added a billion dollars per plant to the cost of construction but the fallout costs of a single failure will dwarf the construction costs of the entire nuclear industry having similar water supply system that I am suggesting.

I think that's purely down to safety reasons, you avoid any extra variables like problems with the pipeline.

Mind you why any have been allowed at all on the east coast of Japan or any of the eastern seaboard of the US when it was/is 100% certain earthquakes and tsunamis would, and will, affect them is puzzling.

Yes but such pipes will be an engineering problem thus solvable. Also storage ponds which might be much more problematic in densely packed Japan.

To put in a few counter reasons.

Having it away from the coast means further to transport fuel (which I presume will come in from the sea) leading to higher risks of leaks inland. Higher risk of pipeline breakage and a smaller chance of getting back ups working. If there is a meltdown then further inland will be more densely populated and the area of evacuation would be significantly bigger. etc...

I completely agree with you that it was a bit stupid and I'm not arguing against that (it's fairly obvious looking at the results) but just some things to think about