Nuclear Reactor

Dmytry

its not radioactive steam, its radioactive elements released by fuel that go along with steam, that you have to worry about. It's also aerosolization of the fuel. The water steam itself is not radioactive, unless it gone critical, in which case it is very short term radioactive.

water table is like ground with gradually increasing water content. For best results, you need corium to drop, with some speed, right into the water. That did NOT happen in Chernobyl. 3 volunteers, true kamikaze, dived into highly radioactive water (on par with that water Tepco doesn't know what to do with), using scuba gear, to open the valve. Their light failed and they had to find valve by hand. 2 of them died later. All of the liquid nitrogen of the western soviet union was used also for preventing this worstcase. All in first week or two.

The west, of course, loves to portray Chernobyl as worst case, even with utter FUD BS about it making some nasty isotopes for military (what isotopes? the problem everyone had was with iodine and caesium, just the two most volatile fission products except noble gasses). Truth is - it is nowhere near as bad as it could have been, thanks to very quick heroic actions of people who died to prevent the worst case.

Dmytry

also, look at table of isotopes for Chernobyl here:
http://www.oecd-nea.org/rp/chernobyl/c02.html
look what fraction was NOT released. And would have been released if the molten fuel was thrown with an explosion, turning it into tiny droplets. Hell, there's no good assessment for health effect of inhaling such particle. What if it sits inside lung, and causes a tiny tiny constant radiation burn that is constantly being healed. A lot of cell divisions, of irradiated cells, plus the autopsy after death from cancer can reveal the fuel particle that caused it. No denying the cause of death with such. With the usual cancers, you can bs about hormesis, you can link to health studies performed in third world, you can play an advocate and try to apply 'innocent until proven guilty' to your defendant, the radiation. With fuel dust, you can't deny it so easily and it very obviously doesn't dilute, just like bullet in russian roulette doesn't dilute over the chambers of revolver.