Dmytry said:
for flood, helipad on the roof + connectors there. Just as there are connectors for fire trucks on the first floor, right? (German nuclear power plants have that AFAIK). Also there's RCIC that keeps reactor cooled for a bit of time (hours?).
US plants where I have been DO have ground level connections for external fire pumps to fill spent fuel pools and inject water into the reactor. Right now they also have diesel driven pumps available on site to perform that function or spray down the building. I can see a benefit in having some resources pre-positioned off site where they can’t be damaged in a site specific event. I am not certain the best delivery site is the roof, simply because that may be inaccessible due to damage, fire, or radiation. Perhaps it requires more than one landing site. Every plant already has a helicopter landing area, usually in a parking lot or cleared area. When plants moved employee parking away from buildings post 9/11 it left large paved open areas available for landing equipment.
Not accusing you of lying, really. You may well be a nuclear engineer all right,
"There was also NUCENG who from earlier discussion of role of CsI in the transport of Cs-137 along with I-131, I have assumed was some sort of bystander with no clue how to relate Becquerel to number of atoms and half life (even if it is 10X the Iodine to Caesium in Bq, it is 1/136 or so the Iodine to Caesium in number of atoms coz I-131 has half life 8 days and Cs-137 has half life 30 years). Which would of been totally fine if he was. I don't mind explaining Bq to people outside nuclear industry and how it relates to half life and number of atoms. I don't think everyone has to know how decay works. Then it turns out he's in fact (or claims to be) a nuclear engineer with many years of experience, involved in uprating, and goes on with his ultra arrogant attitude that he knows enough and has nothing to learn. Right, precisely the kind of person I'd trust with uprating.
Really, this forum is such an eye opener."
Those are your words Dmytry. Have I disrespected you, your opinions, or even your arguments? I think most of the posters here would read that and at least think you have a low regard for my input on these forums.
the thing is, I think I misunderstood your attitude about safety especially when it comes to things such as criticality. It appeared as if you have view that it has to be presumed that there is no criticality. Sorry if that is not what you meant and you were simply playing devil's advocate. IMO it has to be presumed that there is criticality if there might be criticality and you don't know. Just like you have to presume there will be criticality if there might be criticality, to avoid criticality accidents, and a lot of criticality accidents look to me like an example of violation of that approach.
There is the problem. You are absolutely wrong about my attitude. I absolutely believe TEPCO and the people on this forum should be looking for evidence of recriticality. But it should not blind us into ignoring other possibilities. Science, Engineering, and Forensic Investigations should be looking for truth, proof of what did happen, not speculation or opinions of what might have happened. That is what I am trying to do here. I have training, information, and experience related to these threads that I will share. I am pro-nuclear. But I respect your right to take the opposite view. Can’t you try to give others on this thread the same respect?
You haven't offered some specific explanation of high iodine levels (highest of everything), yet you say it may be caused by something else. Well it might be, but for start one thing it can't be caused by:
CsI role in transport of Caesium : Caesium Iodide has something around 1360 Bq of iodine for 1 Bq of Caesium, so it cannot be that everywhere we have CsI leaking keeping the Cs to I ratio constant, to propose so is to be unaware of mol to Bq conversion.
Ditto for other caesium+iodine chemical compounds. Once again, I may have misunderstood your point on CsI, not sure why CsI was brought up, in the solution there is no CsI anyway, just the ions, so I thought you were explaining the ratio with CsI leaving the fuel.
Furthermore, there has to be a giant disparity between relative rates of transport of caesium and iodine from fuel into the water for the spent fuel pool #4 and for all the reactors. 3 orders of magnitude. While for 3 other reactors it is same order of magnitude (and same order of magnitude ratio as for Chernobyl i think, and TMI, but someone should check the numbers).
Why would it hit the spot where it is same order of magnitude as other reactors a few weeks ago? Luck?
I have provided an estimate of the total amounts of I-131 and Cs-137 that were available for release. At the time of shutdown on March 11, the core in unit 2 or unit 3 21 different isotopes of I and 20 isotopes of Cs. There was a total of 17.6 kg of I and 230 kg of Cs. In terms of activity that initial source term consisted of 2.8E18 Bq of I and 1,7E14 Bq of Cs.
I provided you with references that describe the chemical makeup of the released I and Cs. 95% of the I released from damaged fuel is released as CsI. I brought that up because that is the predominant chemical form for transport of Iodine. Other forms include Iodine gas, HI and possibly some organic compounds.
If released into air CsI is agglomerative. It forms clumps with other CsI molecules. It can be filtered from air easily. It tends to deposit readily. It is hygroscopic. It likes to jump into the nearest pool. Once there it is in Cs+ and I- ions. If the pool becomes acidic Iodine gas will re-evolve and be released to the atmosphere. In other words it is not likely to go very far.
Even with 95% of Iodine hooking up with Cs, there is still a lot of excess Cs being released. Cs is a reactive metal. Cs readily reacts with many chemicals including water where it forms a strong base CsOH and releases hydrogen gas. It is non-volatile and will not boil off. It will plate out or deposit. As you say, it will have very different transport characteristics from Iodine particulates (CsI) or gasses. If you get that point you will understand why a single measurement at a sample point is very difficult to interpret the I/Cs ratio because Iodine and Cs are not transported the same ways.
I am not sure I understand your reference to 1360 Bq of Iodine per Bq of Cs. If a molecule of CsI is composed of Cs-137 and I-131 the I is more likely to decay first because its half life is about 1688 times shorter. But a CsI molecule may form in any combination of isotopes of I and CS including stable ones. It isn’t luck it is physics and chemistry.
Dmytry, I have provided this information as factually as I can and have explained or posted references where I obtained this information. Check out my post #4632. In this case I cannot provide a definitive counter to passible criticality. I am not convinced, but us devils advocates can be pretty stubborn.
This forum is interesting and informative. If we can all keep the rhetoric down and respect each other we will have a much better chance of making this forum useful. We’ve already seen one thread shutdown, we all lose when that happens. You seem to see things so clearly, but you lose any chance of persuasion when you belittle others or call them stupid, or liars. Come on in, the water is fine, even if it glows in the dark. Peace?
