Hacker News Reader

Comment by weinzierl | Hacker News Reader

He says that even in the case of a total meltdown (which hopefully will not happen in Fukushima) we will be save because everything will be contained in the third containment.

What I don't get is how cooling is supposed to happen in this case. I think they still would have to pump sea water into the containment which would then get contaminated not only by neutron activation but also with Uranium, Cesium, Iodine etc.

What happens to the seawater then: Will it be released into the environment? Is it in liquid form or will it be released as steam?

View on HN

You filter out the other elements, and release the water.

Water pretty much can't get radioactive. (For more than a few minutes.)

The longest radioactive oxygen you can make in a reactor has a half life of 26 seconds.

For hydrogen, deuterium is not radioactive, and tritium can't be made in a light water reactor.

So water effectively can't get radioactive.

That's why I wrote "get contaminated not only by neutron activation but also with Uranium, Cesium, Iodine". I doubt that in the current situation there would be the necessary facilities to filter out those elements, but I would be interested in having more information on this.

Well, the OP says there are such facilities. (The contaminated water can be kept in the containment till the facilities have recovered from the earthquake if they are currently down.)

As far as the steam is concerned this puts my mind at a rest. Quote from http://allthingsnuclear.org/post/3792741638/containment-at-f... "In this situation, the vented air would be routed through a high-efficiency particulate air (HEPA) filter, charcoal beds, and another HEPA filter to remove as much radioactivity as possible before being released from a very tall stack to dilute the flow as much as possible."

When you say the contaminated water can be kept in the containment, does that mean that they are basically flooding the containment with seawater? My impression was that the there is still a need for cooling (i.e. cool water in, hot water out) in case of a total melt down.

They are just flooding it and letting the water boil off.

If they could actually circulate water they wouldn't be in this situation.

And they have these filters right there, handy and ready to use just in case they started pumping in sea water?

They could probably hack up a particle filter together pretty quick, but unlikely do any desalination. Any reactor which got salt water in it is very much totaled.

Since they asked the prime minister for permission to pump sea water, I'm guessing that it was an option all along i.e. they have the facilities to do just a thing. The whole defence in depth concept relies on having a bazilion emergency options.

They don't have to use them till it's over.

The water is being boiled away, not circulated with pumps.

Remember, they pump in salt water, without prior desalination. It will get radioactive, although to which extent I have no idea.

Not very.

The worst sodium has a half life of 15 hours.

The longest chlorine has a half life of 360,000 years, but is barely radioactive. The rest are all under an hour.

There's other stuff in sea water though. But not in large quantities.

Reply on news.ycombinator.com