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Fukushima To Dump 76 Million Bananas Into The Sea

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OK, the calculation doesn’t entirely stand up any more but it is still indicative:

Japan has announced it will release more than 1m tonnes of contaminated water from the wrecked Fukushima nuclear power plant into the sea, a decision that has angered neighbouring countries, including China, and local fishers.

Official confirmation of the move, which came more than a decade after the nuclear disaster, will deal a further blow to the fishing industry in Fukushima, which has opposed the measure for years.

The prime minister, Yoshihide Suga, told a meeting of ministers on Tuesday that the government had decided that releasing the water into the Pacific Ocean was the “most realistic” option, and “unavoidable in order to achieve Fukushima’s recovery”.

The plant’s operator, Tokyo Electric Power [Tepco], and government officials say tritium, a radioactive material that is not harmful in small amounts, cannot be removed from the water, but other radionuclides can be reduced to levels allowed for release.

As I pointed out that near decade back this has always been the only sensible thing to do. Greenpeace ain’t happy of course:

Greenpeace Japan said it “strongly condemned” the water’s release, which “completely disregards the human rights and interests of the people in Fukushima, wider Japan and the Asia-Pacific region”.

“The Japanese government has once again failed the people of Fukushima,” said Kazue Suzuki, the group’s climate and energy campaigner.

“The government has taken the wholly unjustified decision to deliberately contaminate the Pacific Ocean with radioactive waste. It has discounted the radiation risks and turned its back on the clear evidence that sufficient storage capacity is available on the nuclear site as well as in surrounding districts.

But then as ever the hippies can go boil their heads. For as I pointed out back then:

There’s much screaming and shouting from the usual suspects about the new radiation leak discovered at Fukushima, the stricken nuclear power plants in Japan. What they’re not telling you is that the radiation leakage is around the same as 76 million bananas. A fact which should help to put it all into some perspective. Here’s Greenpeace:

Environmental group Greenpeace said Tepco had “anxiously hid the leaks” and urged Japan to seek international expertise.

“Greenpeace calls for the Japanese authorities to do all in their power to solve this situation, and that includes increased transparancy…and getting international expertise in to help find solutions,” Dr Rianne Teule of Greenpeace International said in an e-mailed statement.

Not that Greenpeace is ever going to say anything other than that nuclear power is the work of the very devil of course. And the headlines do indeed seem alarming:

Radioactive Fukushima groundwater rises above barrier – Up to 40 trillion becquerels released into Pacific ocean so far – Storage for radioactive water running out.

Or:

Tepco admitted on Friday that a cumulative 20 trillion to 40 trillion becquerels of radioactive tritium may have leaked into the sea since the disaster.

Most of us haven’t a clue what that means of course. We don’t instinctively understand what a becquerel is in the same way that we do pound, pint or gallons, and certainly trillions of anything sounds hideous. But don’t forget that trillions of picogrammes of dihydrogen monoxide is also the major ingredient in a glass of beer. So what we really want to know is whether 20 trillion becquerels of radiation is actually an important number. To which the answer is no, it isn’t. This is actually around and about (perhaps a little over) the amount of radiation the plant was allowed to dump into the environment before the disaster. Now there are indeed those who insist that any amount of radiation kills us all stone dead while we sleep in our beds but I’m afraid that this is incorrect. We’re all exposed to radiation all the time and we all seem to survive long enough to be killed by something else so radiation isn’t as dangerous as all that.

At which point we can offer a comparison. Something to try and give us a sense of perspective about whether 20 trillion nasties of radiation is something to get all concerned about or not. That comparison being that the radiation leakage from Fukushima appears to be about the same as that from 76 million bananas. Which is a lot of bananas I agree, but again we can put that into some sort of perspective.

Let’s start from the beginning with the banana equivalent dose, the BED. Bananas contain potassium, some portion of potassium is always radioactive, thus bananas contain some radioactivity. This gets into the human body as we digest the lovely fruit (OK, bananas are an herb but still…):

Since a typical banana contains about half a gram of potassium, it will have an activity of roughly 15 Bq.

Excellent, we now have a unit that we can grasp, one that the human mind can use to give a sense of proportion to these claims about radioactivity. We know that bananas are good for us on balance, thus this amount of radioactivity isn’t all that much of a burden on us.

We also have that claim of 20 trillion becquerels of radiation having been dumped into the Pacific Ocean in the past couple of years. 20 trillion divided by two years by 365 days by 24 hours gives us an hourly rate of 1,141,552,511 becquerels per hour. Divide that by our 15 Bq per banana and we can see that the radiation spillage from Fukushima is running at 76 million bananas per hour.

Which is, as I say above, a lot of bananas. But it’s not actually that many bananas. World production of them is some 145 million tonnes a year. There’s a thousand kilos in a tonne, say a banana is 100 grammes (sounds about right, four bananas to the pound, ten to the kilo) or 1.45 trillion bananas a year eaten around the world. Divide again by 365 and 24 to get the hourly consumption rate and we get 165 million bananas consumed per hour.

We can do this slightly differently and say that the 1.45 trillion bananas consumed each year have those 15 Bq giving us around 22 trillion Bq each year. The Fukushima leak is 20 trillion Bq over two years: thus our two calculations agree. The current leak is just under half that exposure that we all get from the global consumption of bananas.

Except even that’s overstating it. For the banana consumption does indeed get into our bodies: the Fukushima leak is getting into the Pacific Ocean where it’s obviously far less dangerous. And don’t forget that all that radiation in the bananas ends up in the oceans as well, given that we do in fact urinate it out and no, it’s not something that the sewage treatment plants particularly keep out of the rivers.

There are some who are viewing this radiation leak very differently:

Arnold Gundersen, Fairewinds Associates: […] we are contaminating the Pacific Ocean which is extraordinarily serious.

Evgeny Sukhoi: Is there anything that can be done with that, I mean with the ocean?

Gundersen: Frankly, I don’t believe so. I think we will continue to release radioactive material into the ocean for 20 or 30 years at least. They have to pump the water out of the areas surrounding the nuclear reactor. But frankly, this water is the most radioactive water I’ve ever experienced.

I have to admit that I simply don’t agree. I’m not actually arguing that radiation is good for us but I really don’t think that half the radiation of the world’s banana crop being diluted into the Pacific Ocean is all that much to worry about.

And why we really shouldn’t worry about it all that much. The radiation that fossil fuel plants spew into the environment each year is around 0.1 EBq. That’s ExaBecquerel, or 10 to the power of 18. Fukushima is pumping out 10 trillion becquerels a year at present. Or 10 TBq, or 10 of 10 to the power of 12. Or, if you prefer, one ten thousandth of the amount that the world’s coal plants are doing. Or even, given that there are only about 2,500 coal plants in the world, Fukushima is, in this disaster, pumping out around one quarter of the radiation that a coal plant does in normal operation.

You can worry about it if you want but it’s not something that’s likely to have any real measurable effect on anyone or anything.

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7 COMMENTS

  1. I simply have to agree with you Tim. I understand that over 50% of the tritium in the oceans is produced by cosmic rays. There is, of course, no way to stop them. Except for solar flares.

    And a major source of ocean radioactivity is dissolved uranium. We can’t do anything about that either. Unless we build fast breeder reactors which’d make it economic to extract the stuff and burn it up.

    There’s simply no point in worrying about a bit more tritium in the ocean, even 76 million bananas worth.

  2. The water also contains caesium and strontium.

    3 melted down reactors. TEPCO needs robots to assess their condition, then eventually remove the fuel. But the radiation in the reactor vessels fries the cameras and the electronics. None of the fuel has been removed. TEPCO admitted years ago that some 300 tons of contaminated water was flowing under the reactors every day. They tried to stop that with an ice wall. Never worked.

    It is now very difficult to find information on TEPCO’s efforts to deal with the problem. Understandable since the truth would trash the Japanese economy.

  3. Donning my rather dusty physicist’s hat:

    A becquerel is simply 1 decay per second, damage also depends on how much energy is involved in the decay. Tritium decay on average releases 5.7 keV of energy into the environment. Clicking away on the calculator, 40 TBq of H³ produces 37 mW of power. For comparison a resting human produces about 100-150 W, over 3,000 times as much power in a much smaller volume.

    Of course, Greenpeace notoriously doesn’t do science.

  4. We in the UK eat 5 Billion bananas a year so we excrete that much radioactivity a week!
    I told my Colombian wife that bananas have radioactivity and she said “Please don’t tell people that – it could destroy the industry in Colombia”. She could be right

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expunct (ɪkˈspʌŋkt)
VERB (transitive)
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