Are you thinking that the radio active material is the actual U235 or it's byproducts that are contained inside the steel 5" thick pressure reactor vessel as compared to the radioactive water steam that's vented out of the same pressure vessel?
It's my understanding that the reactor at Chernobyl was destroyed and that uranium was released in that explosion.
In this Japan incident the Daiichi unit 1 being a boiling water type reactor is still intact and that they vented some steam pressure out of the steel reactor vessel but the vessel itself is intact. But the steel and concrete building that surrounds the reactor vessel was destroyed when the hydrogen in the steam entered the building and exploded when it came into contact with oxygen and a spark or ignition source of some kind. This blew the top 1/3 of the containment building and the roof off. The explosion also must have spread the radiative steam into the atmosphere where the wind blew it downwind and contaminated people in it's path. Not sure what the radiation levels were. How many millirads or rad were measured in the air.
But they are reporting that Cesium 137 and radio active iodine of some kind has been measured.
Bill Nye the Science guy was on CNN last night and said that the control rods inside the reactor are made of Cesium and that's where the cesium 137 came from. So that tells me that the reactor is melting the control rods as there is not enough water inside the reactor to cover the fuel rod and control rods. Therefore they are melting where the water is not covering them. Water seeks its own level and I must assume that as the water level drops the top of the core heats up and boils the water into steam which is vented and thus there is less water inside the pressure vessel and this goes on and on unless they get the pumps started up and pump cooling water into the pressure vessel to cool it down.
Since the reactor was shut down automatically the control rods should be dropped down into place and absorbing neutrons to slow down the fission chain reactions. But that it still take days for the uranium to cool down and without water to cool it off the uranium 235 will get so hot that it melts the control rod and could melt the steel containment vessel and allow the U235 to drop out of the floor of the pressure vessel. That would be the worst case meltdown. Right now we have a partial meltdown from what I understand.
But most all the radiative U235 is still contained inside the 5" thick steel pressure reactor vessel. But how hot is the U235 and has it reached a critical mass where it can't be cooled down to prevent it from melting the steel pressure vessel?
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Originally Posted by CCIP
1000x normal radiation level is actually a small number. I'm too lazy to do the exact math here, but you would easily need the radiation level to be hundreds of thousands of times higher than normal background radiation that we all experience daily to even begin to get sick. It SOUNDS like a lot, but it's not.
Then you also have to keep in mind that this is confined to a very small space. 1000x in a closed control room, even assuming it escapes, would mean that anywhere outside that the numbers are even smaller.
Sounds like there is still quite a battle ahead to contain the radioactive steam though. It sounds like they may end up venting some of it out, which is of course a PR fiasco. Again, there is only a minute chance that it would pose a danger to anyone or anything before it flies away and dilutes in the atmosphere, but the prospect is scary. Still, I don't think we should sensationalized. The comparisons to Chernobyl are not terribly appropriate here since unless something goes so awry that the steam blows out the currently-airtight reactor container while the reactor melts down, there is zero chance of any actual nuclear material escaping. And for that to happen right now, they would have to screw up really, really badly. It doesn't sound like they will.
The Chernobyl comparisons aren't really appropriate here. On the other hand comparisons to Three Mile Island may be. But there is a big difference between escaping coolant and escaping reactor material.
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And I just saw on BBC that Tokyo Electric Power has now confirmed that they 'released a small amount of vapor' from one of the reactors to ease the pressure.
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