Water, aka H2O, doesn't activate so it is not radioactive, it can however carry radioactive isotopes in solution. Is the groundwater flowing from the neighbouring area? (implied) then the it is carrying cesium from the environment away (good thing if you want to move back into the neighbourhood) is it picking up new contaminants from a broken reactor vessel?
I wonder if anyone has a better source for data here.
What? Tritium is an unstable hydrogen isotope that is radioactive, no matter what molecule it is found in. Combine that with acid-base chemistry which revolves around the disassociation of hydrogen from water and that tritium can end up as a beta emitter anywhere in the body, including in actual strands of DNA [1]. What radioactive isotopes the water carries as a solute is irrelevant to the presence of tritium in the molecules.
I had originally dismissed Tritium as a candidate for the contamination because its nominally only in the reactor water and the Reuter's article talked about 'groundwater' (which is the name nominally given to water that accumulates in aquifers as a result of soil percolation).
Apparently TEPCO is losing control of the reactor coolant water which is a different thing.
That said, Tritium [1] isn't a particularly "bad" agent as it decays into Helium3 (great for fusion reactors if you've got one :-) and then floats away.
Certainly the long-term danger is more from what the water will carry in solution than from the water itself though.
Oh spare us the cloak and dagger. I don't think oxygen radioactivation has been classified for about 80 years now.
There's even a pretty good wikipedia page at
http://en.wikipedia.org/wiki/Isotopes_of_oxygen
The "natural" stable isotope O-16 needs to get triple neutron activated before you get an unstable isotope O-19 and the half life of that is like a minute. So its about half a million minutes per year, and its been about two years, so thats about a million half lives later... I think all the O-19 is long gone.
I do agree 100% that the "stuff" dissolved in the water is about a zillion times more important than the oxygen itself.
Its so mainstream there's some interesting radio oxygen dating work done using the Dole Effect, which also has a wiki page. TLDR is photosynthesis preferentially concentrates certain O isotopes so you can make all kinds of assumptions about glaciation and where plants are growing (ocean or land) given some 16O:18O ratios.
http://en.wikipedia.org/wiki/Dole_effect
There's even a cool wikipedia article with a UTF-8 name.
http://en.wikipedia.org/wiki/%CE%9418O
Which brings you to the greater topic of isotope geochemistry
http://en.wikipedia.org/wiki/Isotope_geochemistry
I'm sure there is at least some cloak and dagger stuff that can't be discussed but there's a simply huge amount of open literature about oxygen radioactivity. I would suspect there's more open lit stuff about isotopic geochemistry than cloak and dagger stuff.
I'm not trying to be cloak and dagger, otherwise I wouldn't have mentioned that a civilian trained nuclear physicist can tell you the exact answer.
However I do not have CG-RN Rev 3 completely memorized and I no longer have access to it, so unless I know for sure something is not NNPI or otherwise protected by the Atomic Energy Act then I don't discuss it. Not that I don't agree that it's pretty crazy that someone who's never been in the Navy could go and look at Wikipedia and discuss it with someone else and be just fine but that the person who's been in the nuclear Navy cannot... but then I've never attributed "common sense" to the military.
With all that said, you haven't hit on exactly what I'm talking about (not that oxygen activation isn't cool). I will say the actual answer is pretty mundane, not at all cloak-and-daggery.
Well if that's how the Navy is, then that's how it is. I was MOS 55R in the army and that's not how how we do it. Then again I was not a 55G which (was) the nuke guys. Maybe they have excessive rules, maybe not.
As for n activation of (pure) water that either the O which is harmless or the H which is almost too obvious or playing games with contaminants. Nobody uses pure water as a coolant other than maybe training/experimental/university reactors, so there's the chemical shim system (and its inevitable contaminants). Or simple mechanical contamination like household dust essentially. Or corrosion (however slow) of non-bulk parts of the reactor, iron, carbon, and chromium from the walls are irrelevant but copper ions from slowly corroding cabling or something. Good luck being nearby the ocean and not having detectable chloride ion concentration, however low. Or dissolved nitrogen from the air, argon etc from the air. Sealing/gasketing material incredibly slowly corroding away. There's more to stainless steel than just Fe/C/Cr so if you corrode enough of it... Not much other options, its a pretty highly controlled area.
And on a further note, I believe that websites which need JS to scroll text are malicious.
The phrase no one on HN has mentioned yet is "biological half life". There's a pretty decent wikipedia article at
http://en.wikipedia.org/wiki/Biological_half-life
Whats important is the ratio of biological half life to radiological half life. Superficially it sounds like you're WAY better off with contaminated water, with a bio half life of about a week, than plutonium around 100 years, a difference of about 4 ords of magnitude. However the half life of 3H is in the 10s of years range and non-RTG Pu is about 20K years range or about 3 ords of magnitude lower activity. So the net effect is it hangs around 4 ords of magnitude longer, but specific activity is 3 ords of magnitude lower, so given X number of atoms, Pu is only about 10 times worse for you than 3H.
All bets off for the Pu RTG isotope that is so short half life it self-melts pretty easy, or that one Pu isotope thats mostly harmless but its decay product is icky (I think 241pu to 241Am where the 241Pu if it wouldn't decay is mostly harmless but the 241Am is icky)
However, the general problem I have with articles about the dangers of radioactivity is, that they almost never contain enough information to actually judge how dangerous it is. It is usually easy to get a factor of 100 or more variation in the dangers of radioactivity, based on the exact contamination scenario, the precise isotope abundances etc. So even Pu is not always very bad, since PuO is almost insoluble in water, which can be used for nice party tricks [1]:
[...] to eat as much plutonium as any prominent
nuclear critic will eat or drink caffeine. My offers
were such as to give me a risk equivalent to that faced
by an American soldier in World War II, according to my
calculations of plutonium toxicity which followed all
generally accepted procedures.
http://en.wikipedia.org/wiki/Tritiated_water
There's an interesting wikipedia article about total body water where you basically figure out how much water is in your body in an absolute sense by consuming some D2O (or I suppose for those who want to live on the wild side, T2O) and the results keep coming up as a half life around ten days in the body. It just doesn't bioaccumulate. I think you're thinking of the heavy metal boneseekers or radioiodine accumulating in the ... gland thats by your throat (I forget?)
You are correct that mathematically you never really excrete all the T2O. However once the level decays below a banana equivalent dose, it just doesn't matter anymore.
Great point bringing up biological half-life by the way, especially as that helps explain why some isotopes are considered more dangerous than others for what may seem to be counterintuitive reasons.
Well, it is water contamination they're talking about. People have the tendency to ingest large amounts of water.
Of course, as you say, knowing the concentration is vital to understanding the risk posed. You could drink gallons of water laced with a gamma emitter if the concentration were low enough (well, not gallons. You'd get water intoxication ;).
Perhaps fish and other seafood (assuming that the tritium concentrates in the seawater around Japan and doesn't get dispered into the wider Pacific). But then the tritium would be mostly "fixed" within the flesh of the fish and end up being mostly self-shielding. Perhaps the ATP w/ tritium and similar products get carried into cells but by that point we're talking about nothing worse than the day-to-day problems of life under the sun, eating bananas, breathing the sweet sweet scent of brick-induced radon, etc.
Also, I think with regard to tritium spilling into the sea, they're probably less concerned about a direct effect on people than on the fish swimming around in it.
http://nuclearsafety.gc.ca/eng/readingroom/healthstudies/tri...
Either way the problem with radioactive materials relates to the concentration in solution of radioactive materials more than the binary "radioactiveness" of the material. After all the human body itself is 'radioactive' if only from the K-40 and C-14 that are present.
Without knowing the concentration of radioactive contaminants like Co-60 and radiocesium that might leak into the sea it's hard to know how much of an 'emergency' we'd be looking at. All we'd know for sure is that TEPCO is incompetent... but then what else is new?