Helen Caldicott and the not-so-fine art of making up nonsense.

Here’s a particularly egregious and scientifically vapid (as you’d expect, of course) interview with Helen Caldicott concerning last month’s damage to the Fukushima I nuclear power reactors… 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.


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