Friday, 9 December 2011

Coal: 1 Fukushima every 600 years

[NOT EVEN CLOSE TO MY ORIGINAL CALCULATION WHICH WAS OFF BY A FACTOR OF  1,000 (not a million) - SEE COMMENTS AND CORRECTED POST BELOW - MY APOLOGIES FOR THE ERROR.]

In December 2007 Scientific American published a report on coal power plant radioactive releases and compared these with those from an operating nuclear energy station. To the surprise of many in the general public, coal station emissions are A LOT higher than an operating nuclear plant.
In fact, the fly ash emitted by a power plant—a by-product from burning coal for electricity—carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy.
High coal radiation release rates were also reported in a study / report from the Oak Ridge National Laboratory in the USA. In fact, the ORNL study found so much fissionable material (Uranium and Thorium) in coal station discharge, that consideration was given to recovering the material for use as fuel in nuclear energy stations.

But how much does a coal station release? From the ORNL report linked above:
According to the National Council on Radiation Protection and Measurements (NCRP), the average radioactivity per short ton of coal is 17,100 millicuries/4,000,000 tons, or 0.00427 millicuries/ton. This figure can be used to calculate the average expected radioactivity release from coal combustion.
Converting this to metric equates to about 0.174 MBq/ton (metric ton).

According to Wikipedia (and again converting to metric), about 6.14 billion metric tons of coal are burned per year.

Multiplying the two means that the radioactive release from annual coal combustion is 1.069 PBq/yr (peta-Becquerels or 1,069,000,000,000,000 Bq).

The nuclear accident in Japan has many reports of total radiation release. Several are listed in Wikipedia. To be VERY generous to the coal industry, lets take the largest airborne release I was able to find (Iodine and Caesium together) = 270 PBq. Then add the largest water release reported 27 PBq for a total of 297 PBq.

But the release continues... at a reported rate of 200 million Bq/h in September. At this rate the total release from the accident will double after 170,000 years. But clean-up and recovery efforts along with natural decay means that rate can not possibly be sustained.

But for my calculation, I will assume the release from Fukushima is double what has been reported or 600 PBq. This is totally unfair to science as well as the nuclear industry, but let's roll with it.

So to summarise:
Coal = 1.067 PBq/yr
Fukushima = 600 PBq (unjustifiably doubled by me)

Therefore: every 600 years worldwide coal combustion releases as much radiation as was released from the nuclear accident at Fukushima  (in reality, it's more like every 300 years). Or in one typical lifetime, coal use will result in the release of around 20% of the activity released from the Fukushima accident. In addition:
  • Coal stations are distributed worldwide
  • Coal emission are unregulated for radioactivity and imposing regulations onto them now is almost impossible
  • Fly ash is typically stored in open air basins that have been known to fail.
While the Japanese are taking action to clean up and recover from the Fukushima accident - granted, at great expense - applying a similar effort to clean up after coal is inconceivable.

11 comments:

  1. Thanks, I have been looking for those numbers. So let's say your 3 month comparison is the best estimate. The U.S. consumes about a quarter of the world's coal. So each and every year, US coal combustion releases as much radiation as 1 Fukushima.

    Does that sound more or less correct?

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  2. I was looking at outdated coal consumption numbers. The U.S. consumes about an eighth of the world's coal annually. So every 24 months, U.S. coal combustion releases as much radiation as 1 Fukushima.

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  3. I think those data are a bit suspect - 174 kBq/kg is higher than any published figure i have seen. See also
    http://www.world-nuclear.org/info/inf30.html
    Also, most of these radionuclides are captured with flyash and bottom ash and buried.
    The ORNL paper is 1993.

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  4. When flyash and bottom ash are buried, they are buried in landfills with a design life of about 30 years. Compare that with the 5 billion year half-life of uranium. However, not all flyash and bottom ash is buried. Much of it is used to manufacture wallboard which is used in housing and other structures. Other large amounts of flyash and bottom ash is stored in large ponds.
    Don Kosloff

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  5. If you convert 0.00427 millicuries/ton the result is 157,990 Bq/ton.
    You are in excess of a factor "1 million".

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  6. I was looking for a source of error after receiving Ian's post. However, I focused on the references... the source of the numbers.

    Thanks for the reviews and comments. The post has been corrected and the error tweeted.

    ReplyDelete
  7. Your analysis is less reassuring than I had hoped. I had thought that the radiation emitted from coal in China was greater than that of Fukushima. From your numbers Fukushima emits at least 600 times more than what China emits. I'm assuming that china is at least as bad as the US in coal emissions.

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  8. Yes, 1000 times off not a million, i'm european and i often confuse point and comma.
    You must also consider that coal fly ashes are far less than 1% in weight and that coal combustion emits through the stack the totality of the volatile elements of the Uranium and Thorium decay chain (e.g radon) but many elements remain in the coal ash.
    So is quiet complex to make a evaluation of the total activity that remains in coal ashes but you can consider that the radiotoxicity of the ash that reamin at the plant is greater than the radiotoxicity of the radioactive materials released.

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  9. I agree. In the real world, it is quite complex. For example Iodine-131 has a half life of about 8 days - so Iodine-131 released as a result of the accident in March has decayed away and does not pose an ongoing risk. Even over the course of my example (hundreds of years), Cesium-137 will be, for the most part, decayed away (half life of about 30y).

    As for China and Rick's post: you've got the numbers now from my post and Ian's comments. These should allow you to crunch the numbers to determine who ranks where. But the simple method would be to just research who burns the most coal.

    One point of clarification though Rick. The Daiichi plants 'emitted' not 'emits'. While the release may not be totally zeroed; it is far, far less than the first few weeks following the accident.

    Coal emissions however continue to expand.

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  10. There is no place on the planet where the burning of coal has made hundreds of square kilometres of valuable land uninhabitable for 30 plus years as in Fukushima.
    The risk of Nuclear is that it's not just atmospheric contamination, its the land and water.

    I have a lot of faith in engineering but absolutely NONE in the people running the plants.

    ReplyDelete
    Replies
    1. I recommend you broaden your scope.

      The vast majority of peer reviewed scientists agree the carbon emissions of coal and other fossil fueled power stations pose a credible risk to life as we know it on the entire planet.

      This is in addition to the health and environmental impacts from mercury, fine particulates and other pollutants released from coal.

      Maybe after gathering some facts your fears could be allocated more rationally.

      Renewable stations will continue to be deployed in Australia (and I'm grateful for that). Sadly, without nuclear, these will be complimented by additional fossil stations. Consider proposed new power projects in Australia:
      15 fossil stations (over 9,000 WMe most are coal, a few brown coal)
      1 hydro (35 MWe)
      1 biomasss (180 MWe)
      3 landfill gas (9.8 MWe)
      1 Windfarm (167.9 MWe)

      I don't trust many in Australia who claim we are already headed for a low carbon economy.

      I am grateful for the carbon tax.

      Delete