Physical Insights

An independent scientist’s observations on society, technology, energy, science and the environment. “Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home.” – Carl Sagan

Helen Caldicott and the fine art of making up nonsense.

with 12 comments

Here’s a particularly egregious and scientifically vapid (as you’d expect, of course) interview with Helen Caldicott… recorded recently on some kind of “environmentalist” podcast.

Now… I could write a comprehensive technical deconstruction and debunking of essentially the whole lot… but I’m only one person, with a finite amount of time.

I’ll get started, just for now, by taking a look at just one particular sentence of nonsense from Caldicott.

Ask questions. Seek the evidence. Ask everybody questions, and never take anybody’s word for it. Are factual statements backed up by evidence? Are quantitative statements backed up by measurements, calculations, or derivations? Can those measurements or derivations be described and reproduced? Read everything you possibly can, and you decide.

Do people like Caldicott have the right idea? Or do people like George Monbiot have the right idea – that beneath the FUD, rhetoric and hysteria, these people have absolutely no real evidence, facts, knowledge or technical literacy at all?

HC: “Well it won’t recover. These accidents go on forever because plutonium’s half-life is 24,400 years. It lasts for half a million years. Thirty tons of plutonium got out at Chernobyl.”

Thirty tons of plutonium “got out” at Chernobyl!?

Personally, that reads many thousands of counts per minute on my baloney detector.

Let’s follow Dr. Caldicott’s favourite piece of advice… let’s read her book. Surely, just like all of Caldicott’s other “references” usually are, it’s got to be “in my book”, right?

“Plutonium is so carcinogenic that the half-ton of plutonium released from the Chernobyl meltdown is theoretically enough to kill everyone on Earth with lung cancer 1100 times, if it were to be uniformly distributed into the lungs of every human being.”

(From Nuclear Power is Not The Answer).

Hmmmm. Curious. It looks like we’ve gone from “a half-ton” in the book to “thirty tons” in this recent interview. Well, so much for “you should read my book… it’s all in the book!”

(By the way… that “kill everyone on Earth with lung cancer 1100 times…” bit is complete baloney. But that’s a story for another day.)

Reactor-grade plutonium typically consists of approximately 1.3% 238Pu, which has a half-life of 87.7 years and a specific activity of 634 GBq/g, 56.7% 239Pu, which has a half-life of 24,110 years and a commensurately far smaller specific activity of 2.3 GBq/g, 23.2% of 240Pu, with a half-life of
6564 years and a specific activity of 8.40 GBq/g, 13.9 % of 241Pu, with a half-life of 14.35 years and a specific activity of 3.84 TBq/g, and 4.9% of 242Pu, with a half-life of 373,300 years and a specific activity of 145 MBq/g.

Taking the weighted sum of all the above, we find that the overall specific activity of reactor-grade plutonium is 545.3 GBq/g, predominantly due to the 241Pu and the 238Pu content.

(Reactor-grade plutonium is considerably more radioactive than weapons-grade plutonium, due to the presence of substantial concentrations of these relatively unstable, high-activity plutonium nuclides. Weapons-grade plutonium is almost entirely 239Pu, which despite being a good fissile fuel, is more stable and less radioactive. The radiological heat output of 238Pu, gamma-radiation (from the 241Am daughter of 241Pu) and the high rate of neutron emission from the spontaneous fission of 240Pu all make these nuclides extremely deleterious and undesirable in nuclear weapon design and engineering.)

The best value determined based on the available data for the quantity of plutonium (a reactor-grade cocktail of different plutonium nuclides) released at Chernobyl is, as published in the reports of the Chernobyl Forum, 3 PBq (3×1015 Bq).

The approximate total mass, based on the best available data, of plutonium released into the environment at Chernobyl is 3 PBq divided by 545.3 GBq/g.

As the British physicist David Mackay put it, I’m not trying to be pro-nuclear. I’m just pro-arithmetic.

It’s 5.5 kilograms.

Incidentally, that’s a very small amount of plutonium compared to the amount of plutonium that has been dispersed around the environment from half a century of nuclear weapons testing. 5.5 kilograms of plutonium is, approximately, the amount of plutonium in the pit of a single nuclear weapon. A single zero-yield “fizzle” of a nuclear weapon with no fission, or a zero-yield one-point-implosion safety test, or the accidental HE explosion (without proper implosion of the primary, as in the Palomares and Thule accidents) of a single nuclear weapon will disperse a roughly comparable mass of plutonium into the environment. (But less radioactivity, since weapons-grade Pu is less radioactive than reactor-grade Pu.)

So, Caldicott has gone from exaggerating the true number by a factor of approximately 100 to exaggerating the true number by a factor of approximately 6000.

Anyway… let’s just step back a minute. 30 tons of plutonium released at Chernobyl? Let’s apply what scientists, engineers and technologists sometimes refer to as the “reasonableness test” or the “smell test”. Can you quickly “smell” the data and determine if it is roughly plausible or not?

The total mass of uranium dioxide fuel in the fuel assemblies of a fully fueled RBMK reactor is about 180 tonnes. That’s about 159 tonnes of uranium, if you take off the mass of the oxygen in the uranium dioxide. When LEU fuel is irradiated at a typical burnup in a nuclear power reactor, about one percent of the mass of the original uranium ends up as transuranic actinides, mostly plutonium, by the time the fuel is removed. So, that’s a total plutonium inventory in the Chernobyl reactor of approximately 1.6 tonnes.

So, if we make a conservative, pessimistic and entirely unrealistic assumption that 100% of the plutonium inventory in the nuclear fuel was entirely vaporised and released into the environment during the Chernobyl accident, that would be 1.6 tonnes of plutonium released to the environment. (In reality, that fraction was something more like 0.34% of the total inventory of plutonium within the irradiated uranium dioxide fuel.)

So, does “thirty tons” pass the smell test? Not by a long shot.

Written by Luke Weston

April 23, 2011 at 6:47 am

12 Responses

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  1. I don’t give a crap about tonnes or tons or kilos of radioactive material it took to blow up two vibrant cities a few decades ago…You do your math & we’ll count the bodies from radiation. Now… that’ll past the “smell test”! Something ain’t jiving Luke. Nuke wizzard or not…Japan will loose a shit load of real estate for centuries to come because of this disaster.
    Please don’t undermine the reality of this total ruin to the area surrounding ground “Zero” @ Fukishima. The Gov. has alrady admitted that the waters are loaded with radiation off the charts & are off limits to fishing,etc. Cities 30 miles away from the no enter zone have higher recordings recently because the winds have changed. Ho-hum, yawn, gotta train more morticians soon! Then you can number crunch!


    April 23, 2011 at 9:48 pm

  2. Caldicott is wearing her environmental-humanist cap in this debate. She is being aggressive with her argument at the expense of scientific fact because of her fear for humanity. Scientists will always argue over veracity which is the admirable and critical basis of the scientific method. So I expect her comments to be critiqued vigorously and questioned by her colleagues.

    But sometimes the cold facts need tempering when there are potential dire consequences at hand. And if anything requires a warning label, it’s a nuclear reaction inside of a dubious “containment” vessel that cannot be simply switched off in an emergency like the one playing out at Fukushima.

    In other words, your learned comments are an important part of the discussion, but no more so than Helen’s dire warnings given the insidious and corrosive power of this energy source toward all things living.


    May 15, 2011 at 8:08 pm

    • +MarkinEugene Dire warnings that there is a monster under the bed are no contribution to humanity or to frightened children either, when there is no such monster. We have been receiving dire warnings from such as James Hansen about a not-very-far-off threat that only nuclear power can prevent, which the wild exaggerations of Caldicott may very well cause, to come to pass.
      Fossil carbon power, i.e. fossil solar power, displaced wind, sun, water, and biomass pretty thoroughly starting in the 18th century. It should be intuitively improbable that for a far larger human population, solar sourced “renewable” energy can make a comeback. But the large atomic nuclei have millions of times as much energy, per kilo, as coal and oxygen, or methane and oxygen. TMI killed NOBODY, Fukushima has NO known casualties — although fear of it may account for deaths of up toe 1500 people who died elsewhere, having been evacuated. Even the infamous Chernobyl’s proven deaths are fewer than one madman in a hotel room in Las Vegas caused with a collection of guns.


      December 13, 2017 at 6:51 am

  3. Thanks MarkInEugene, an important rebalance, I think, compared to this hit-piece from someone well-versed with the industry.

    I notice there is no update more recently, detailing the meltdowns, and the extent of the actual Level 7 disaster, and that it is a major failure for the industry.

    Why not turn your mind to a different approach? What it is likely to mean for real human beings on the ground? Or who eat the fish? Or who breathe the air at the wrong time and the wrong place? The embryos malformed, the congenital defects, the children who die of heart attacks, the thyroids to be excised, the leukaemias that develop and , of course, the cancers.


    September 22, 2011 at 6:18 pm

    • +bandido The disaster is that these reactors, with zero gaseous emissions, have had their output replaced by gas turbine and cola burning plants that daily emit poison gases into the air, and carbon dioxide that is a poison to every calcium-using organism in the oceans.
      Even thirty tons of plutonium, which needed fantastic design accuracy and purity to be a bomb, as a source of radioactivity is puny. But the article told you that, and uou paid no attention.


      December 13, 2017 at 6:14 am

  4. I always enjoy your posts, I just finnished up with LNT, this is a good article also 🙂 Thanks for the blog!

    radon newburgh

    May 9, 2012 at 5:51 pm

  5. @MarkInEugene…So what you are saying is that Caldicott was using emotion instead of facts to win her argument. The problem is that humans are terrible at evaluating complex issues That is why science and rational discussion are so important in these debates. Whipping people up into an emotional frenzy by “tempering the facts” is counterproductive. Climate change, Species extinction, Energy production are all part of a interconnected complicated problem that will be very hard to solve even if we can all communicate rationally.

    @martindeane…Here is a recent update to counter your unfounded fear of malformed embryos etc. from the respected publication “Nature”

    “Experts agree that there is unlikely to be a detectable rise in thyroid cancer or leukaemia”

    “A far greater health risk may come from the psychological stress”

    That is stress caused by people like Caldicott who “temper the facts”.
    Causing people unneeded psychological suffering does not sound like the actions of a “Humanist”

    Mike Johnson

    July 29, 2012 at 8:13 pm

  6. I just want to comment on one of Caldicotts hoary old chestnuts that is essentially meaningless….

    “theoretically enough to kill everyone on Earth with lung cancer 1100 times, if it were to be uniformly distributed into the lungs of every human being.”

    One could say the same thing about the water in an Olympic swimming pool. “enough to drown everyone on the planet…”

    The real question is whether there is a plausible mechanism for this bit of magic to occur. It turns out that Plutonium is heavy and not very mobile in the environment. Coupled with the shear size of the planet, this makes her idea preposterous. But as people have said before, never let the facts get in the way of a good story.

    Mike Johnson

    July 29, 2012 at 8:27 pm

  7. “released at Chernobyl is, as published in the reports of the Chernobyl Forum, 3 PBq (3×1015 Bq).”
    If i am not mistaken, that was the total iodine, cesium and strontium total. They didn’t count that offensive element. Note the transmutation of Neptunium239 as a source of plutonium, that’s usually not accounted for.


    February 21, 2013 at 6:25 am

    • The popular scaremonger approach of quoting gigabecquerels of “radioactivity” released into the air or the water “in the first ten days” or whatever is like quoting rush hour traffic in trillions of millimetres per hour.
      A typical banana releases 15 Bq of radiation, constantly, from the tiny amount of the radioactive isotope 40 of the valuable potassium that is a good reason for eating fruit. Eat the banana and your inside continues to receive that same RATE of radiation. It is not a measure of the rate at which radioactive banana build up inside you.
      In particular, reporting that N x 10^12 becquerels of neptunium were released in the first ten days is manifestly false. If N was 64 on the first day, we can be quite certain that three days or so later N was 32 or less and on the ninth day, only 8. Because neptunium 239 has a half life of about three days.
      Besides which, one Bq is one radioactive decay per second, and 239 grams of Np-239 is just over 6,00000,00000,00000,00000,000 atoms. That’s 6.0*10^23, Avogadro’s number.


      December 13, 2017 at 6:33 am

  8. my friend was searching for 2011 form 8615 several days ago and located a web service with a searchable forms database . If people need to fill out 2011 form 8615 too , here’s a

    Stephen Scroggs

    August 1, 2016 at 8:41 pm

  9. A valid point about the actual emissions from Chernobyl. Although I’m not so sure about the total Pu on site. I was under the impression that there was a waste stockpile of Pu waste under the reactor core. Still, the stockpile is unlikely to have contributed to the emissions. Perhaps Dr Caldicott mistakenly included the stockpile in what “got out”?

    Sam Hadley-Jones

    April 28, 2017 at 10:12 pm

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