[ad_1]
It is a huge amount of irradiated water from the Fukushima nuclear power complex that Japanese authorities have decided to dump into the sea. I suspect that at some point it is going to return to nature, whether we like it or not.
If I understand the facts correctly, this water is primarily radioactive due to tritium content. Thus it is not what is “dissolved†in the water but the water itself that is radioactive.
Tritium has a half-life of 12.3 years, which means that a little more than half of the tritium atoms that were left there at the time of the earthquake, tsunami and reactor meltdown in March 2011 are still there.
It decays into helium 3, which – though a bit exotic – is neither radioactive nor toxic nor environmentally impactful.
Tritium does not bioaccumulate. If you ingest it, half will be out of your system within a week or two weeks and there is no indication that that is different for any living species.
The natural abundance of tritium is 10 to the minus 18th power (a decimal followed by 17 zeros and a one) compared with normal hydrogen (with which it is chemically identical; that is, tritium ends up as part of the water).
The mass of the oceans is about 1.4 times 10 to the 24th power kilograms. If one considers that hydrogen makes up 11.1% of the mass of water (0.111), that means that there are about 150 kilograms (more or less) in the oceans naturally.
Tritium decay produces only a beta particle (high energy electron) and an anti-neutrino (does not generally interact with matter). No gamma rays to speak of. The energy, about 18 KeV, is so low the beta particles will not penetrate human skin (only dangerous -and not all that dangerous – in low concentrations if you drink a fair amount of it).
Just to put it in perspective, radium decay (just one stage) produces as much as 300 times this amount of energy, much of it in gamma rays.
It is true that oceanic water is in layers and these take years and in some cases decades and centuries to mix.
We can assume that at any given time almost all the natural tritium is in the top fifth of the water, since most natural tritium is created in our ionosphere through cosmic ray/solar wind impacts (so it would come from the atmosphere into the oceanic surface).
So to come up with a more realistic figure I would then raise the effective concentration in the oceans to about 50 times ten to the minus eighteenth power.
According to TEPCO there are about 9.5 grams of tritium in all forms in water held or stored by TEPCO at Fukushima (2014 numbers). I am going to increase that by half again just to be on the safe side and simplify calculation and say 15g.
The 15 grams out of the total 150 kilograms (150,000 grams) is about 1/10,000, meaning that if we had dumped all the Fukushima water in 2014 (the tritium is, all factors considered, going to be less now), within a few days given natural diffusion processes the concentration of tritium in the area where it was dumped would be more concentrated by a tenth of a percentage point or less (do the math) and within a year or so by less than 1 one hundredth of a percent.
That is, exposure is going to be less than on a typical airline flight.
While I may sympathize with hysteria, I don’t respect it. The only way that contaminated water is going to be dangerous is if the tanks leak and contaminate the water table. That will eventually happen if things are left as they are.
On the other hand, if now half-degraded (into harmless helium) water from which all other contaminants have been stripped is released, slowly, into the ocean, there will be negligible impact.
That does not mean we can dump the waste from any nuclear accident anywhere we want any time we want. But in this case, the solution we are maintaining is probably riskier and in storing water that is not going to affect anything, it certainly wastes resources that could be spent better on cleaning up Fukushima.
I am not in this instance beating up on the press. Without some robust reporting, I would not have the information to analyze the situation and express an opinion.
But in the alternative, I am not so sympathetic to readers (including various governments and politicians by the way) who almost a century into the nuclear age are still so ignorant about risk as to be panicked about the possibility of dumping the water.
It is possible, by the way, without being hysterical and misleading, to feel that it is wrong to dump this water.
But that is not typically what we see. Human beings (billions of us) are going to have an often adverse impact on the Earth whether it is through burnt hydrocarbons or destroyed habitats or overfished oceans or any one of many things.
One cannot be in the world and not have an impact on it. That is a childish fantasy.
The point is to avoid actions that do meaningful damage. This Fukushima water dumping issue is, I suspect – unlike the event that originally spawned it – a bit of a tempest in a teapot.
We can and should be strict and severe as to the bad practices that led to the events at Fukushima. But not only does treating everything nuclear with a torch-and-pitchfork mob mentality hobble the authorities’ effective management of the industry and any problems (because their PR people end up making more decisions than their engineers) but, beyond that, we cheat ourselves out of realistic solutions to things like climate change mitigation.
If I were giving due regard to PR and even safety, I would recommend shipping the water out to sea over a long period of time and releasing it, and not all at one place, so that any increases over effective tritium background would be negligible.
Also the density of living things in the sea is much, much higher near the coasts of land masses. And the potential rate of dilution of the disposed-of water is far lower near land.
Grady Loy retired as corporate counsel to a leading Japanese chemical company and is a commentator and writer based in Yokohama.
[ad_2]
Source link
