NUCENG said:
Questions:
1. Where is the Japan CTBTO sensor? Are the peaks in CTBTO data correlated with wind direction to the sensor from the Fukushima site?
2. Have the peaks been checked for increases in other short half life isotopes?
3. If the peaks are due to short recriticalities shouldn't the increase be followed by an exponential decay from the new peak? It looks like they drop right back to the decay trend that was in place before the short peaks.
4. Shouldn't the Unit 1 drywell radiation detectors show some time delay to the CTBTO sensor unless that sensor is on site.
Regarding questions #1/2 see Bodge's post
https://www.physicsforums.com/showpost.php?p=3342625&postcount=9081".
Regarding question 2: All these measurements have been and are being done, but no exact details published by Tepco (usually only I and Cs, as you know). Unless these are published one cannot rule out the possibility that there is something going on.
Regarding question 3: It would require relevant production of new FPs to make a relevant difference to a "background radiation" approaching 250 Sv. So can the absence of a decay ramp really be a proof that there is no oscillating recriticality in a small core part in the RB or CV?
Wouldn't this send out intensive radiation during reaction until dying out, and after that go unnoticed like an recently used, but now inactive "Slotin toy" probably would in this
really big nuclear mess?
Regarding question 4: The distance of the sensors (100/200km) will, depending on the weather, eventually cause some phase and amplitude shift with the measurements on site (that usually are not published en detail). If I consider this there I cannot deny that to me there seem to be some coincidencies.
robinson said:
So how does plutonium get out of a nuclear reactor? Or spent fuel pond? It's not like the airborne isotopes, wafting about in the air, the steam, the smoke. Right?
It doesn't float or escape in a cloud of steam. Does it?
Yes, but not that easily like Iodine, Cesium or even noble gases for instance.
As Plutonium is very heavy and reactive, most of it usually clings to other material, making "hot particles".
Most of them fall down in a range of around 30 km, but some are distributed worldwide.
This btw is lesson learned from old russian nuclear mishap experience, so the 30km zone around Chernobyl.
Experience from many accidents/"experiments" has shown that more than 9/10 of the emitted plutonium goes down in a radius of 30km.
~kujala~ said:
I have heard that soil chemistry is complicated.
It is, indeed. So the behavior of the various elements which we worry about some isotopes. In fact there has been much research. Just google "soil nuclide distribution" or such.
~kujala~ said:
There could be hot spots of iodine on the debris/in the ground and then depending on how water is flowing/diluting we could see some sudden changes in the relative amount of cesium/iodine although this would not necessarily prove re-criticality.
Afaik iodine is one of the most volatile non-gaseous nuclear contaminants and mostly is present in ion form, I don't think that there are to be expected hot spots/hot particles like those of Plutonium, Strontium etc. So I doubt this a bit.
joewein said:
elektrownik said:
Interesting why they are installing this not in center of SFP, sfp is weakest there ?, the point where they are installing it is strongest I think (because of drywell thick): http://www.tepco.co.jp/en/news/110311/images/110607_1f_2.pdf
The spot marked in green on the bottom left diagram is where the steel support pillars will be - under the middle of the pool.
Looks like they'll also build a concrete wall at the red spot next to the dry well wall.
This worries me. The photos reveal interesting things.
1. It is interesting that the floor and ceiling of the room is not shown in the photos.
Are they already cracked? Is there danger of other cracks extending?
If not so, why then the support?
2. The support bars do not have diagonal reinforcement bars, as would be necessary to avoid deformation under load.
Instead they show mounting plates for mounting something like metal grouting forms.
This indicates they will probably mount steel plates as rebar and concrete form onto the pillars and pour in concrete, else the SFP support would probably not be very earthquake resistent.
How will they vibrate/compress the concrete correctly with that dangling SFP above them?
Or even drill/hammer out mounting holes in the floor, walls and ceilings etc?
Really scary construction site!
3. If the assumption is correct that they just fill the inner half of the room below the SFP with concrete this could make bad things even worse.
The walls are covered with thick epoxy painting, what makes up a very strong insulation. The concrete will not stick well to the wall, until this insulating paint cover is removed with demolition hammers, sanding etc.
There is no rebar connection to keep this heavy blob of concrete in place in case of a new heavy quake, as it does not adhere with the walls/floors.
So this loose giant thing will put heavy additional loads onto the already-weakened structure on the next big quake.
This kind of "support reinforcement" could finally pry open, crack and leak the still-intact SFP walls!
If Tepco is really so desperate doing such then I wonder what surprises this haunted plant still has for us what we have not been shown yet...