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

Posts Tagged ‘Chernobyl

Helen Caldicott and the fine art of making up nonsense.

with 7 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

The battle for Chernobyl.

with 18 comments

Last month I got into a discussion with some people about the Chernobyl disaster, following the 22nd anniversary of the catastrophic Soviet reactor accident, and this documentary film was mentioned:

The Battle for Chernobyl.

To put it lightly, this film is an astonishing bunch of rhetorical baloney.

I’m not trying to downplay the public health consequences of the Chernobyl accident – but I’m downplaying the inaccurate or false claims made by certain groups, as distinct from the body of evidence of real, documented and substantiated (and very significant impacts).

Despite the known public health impacts, some people continue to make claims that are either just not true or are completely unsubstantiated – for example any claim that there are children, today, with an increased incidence of thyroid cancer, which just isn’t true – any children who were exposed to the short-lived iodine-131 source term in 1986 are adults today, 22 years later, and the iodine-131 decayed away quickly, within months.

Now, to look at the video:

From the gaping hole, a spray of fire, charged with radioactive particles in fusion, sprays a thousand meters into the sky.

Right from the outset, it’s completely obvious that for the next hour and a bit, science is tossed aside, and rhetoric is the first and only order of affairs.

The radioactive fallout is going to be 100 times greater than the combined power of the two atomic bombs dropped on Hiroshima and Nagasaki.

Some simplistic comments have often been made in which the radioactive release of the Chernobyl event is claimed to be 300 or 400 times that of the bomb dropped on Hiroshima. However, in sensible terms of radiological impacts, the two events can not be simply compared with a number suggesting that one was x times larger than the other.

Radioecology after Chernobyl – some good literature.

The total combined energy yield of both of the nuclear weapons used in Japan was about 35 kilotons of TNT equivalent – or about 41 gigawatt-hours. The Chernobyl Unit 4 reactor, with a thermal power output of about 3 gigawatts, produced that same amount of energy, and created about the same amount of fission-product activity, every 13.6 hours or thereabouts. Given that a nuclear power reactor contains fuel that has provided that kind of power output for perhaps as long as several years, of course there’s a larger inventory of radioactivity contained in the reactor fuel.

Iodine tablets swallowed to counteract the effects of radioactivity.

Iodine prophylaxis only prevents the body from uptaking iodine from the environment – which might be contaminated by radioactive iodine-131. It in no way “counteracts the effects of radioactivity”.

“The radiation level above the reactor is over 3500 R, almost nine times the lethal dose.”

3500 R over what length of time? The strength of an ionising “radiation field” in such a situation can only sensibly be expressed as roentgens (or sieverts or similar unit) per hour (or per unit of time).

0:36:40

If over six hundred pilots were “fatally contaminated with radiation”and killed, and this is known to be true, why have the Chernobyl Forum, the IAEA, the WHO, the UNDP, the UNSCEAR, Russian or Ukrainian governments never mentioned it? Can it be proven to be true, before the international community, by these people?

0:37:08

Why does none of this film show any artefacts on the film resulting from radiation damage?

0:38:20

The infamous “elephant’s foot” “magma” doesn’t look “white-hot” at this stage, although that’s how it’s described.

0:43:45

Again, the level of radioactivity is implied to be so very high – and it was high – yet it was not high enough to leave artefacts on the camera film. I don’t know exactly what sort of radiation dose is required to effect a piece of photochemical film (Remember that stuff, that was used before digital photography?), but I really expect it to show some damage under these conditions.

0:44:45

If you’ve got documentary evidence of these lives lost as a direct result of the disaster, that don’t appear in any of the UN’s findings, then I’m sure the UN would love to hear about it.

0:52:30

Oh dear – it’s “imagined” health physics, romanticised Hollywood fiction style.

“It finds a way in, and knocks you out”.

1:03:00 or thereabouts:

7000 R/hr – and still no effect on the video camera film. I wonder how strong the ionising radiation field needs to be to affect it?

1:12:30 -

“…The visit stirs up painful memories. He was fatally exposed to radiation during the seven months he spent covering the battle. Since then, he’s had to be hospitalised for over two months each year.”

He was fatally exposed to radiation? Oh, really? So you’re reanimated a dead man to interview for the program?

Chernobyl showed us the true nature of nuclear energy in human hands

No, Chernobyl showed us the potential for folly associated with the Soviet way of doing things back then. Keep in mind that the non-Soviet world has never even come remotely close to experiencing such an accident.

1:31:20:

“Inside, there are 100 kilograms of plutonium.

One microgram is a lethal dose for a human being. That means there is enough plutonium to poison 100 million people.”

Even assuming that “one microgram of plutonium is a lethal dose for a human being”, which it isn’t, I expect that somebody who is really a nuclear physicist should know how to count, and not allow such a glaring error of arithmetic to go uncorrected.

“The half-life of plutonium is 245,000 years.”

In order of descending half-life:

Pu-244: 80 million years

Pu-242: 373,300 years

Pu-239: 24,100 years

Pu-240: 6564 years

Pu-238: 87.7 years

Pu-241: 14.35 years

Pu-236: 2.858 years

The nuclides bolded are the most common ones. I don’t know about you, but Iexpect someone who is a nuclear physicist to get that right, and not just pull some nonsense number out of thin air! Again, not one of these plutonium nuclides has the half-life claimed in the film. What’s more, no credible nuclear physicist would state that “the half-life of plutonium is such-and-such” without specifying which nuclide he was talking about.

But wait – if you’ve watched the video, there are a couple more scenes that you almost certainly haven’t overlooked:

“Yet, it is thanks to these men that the worst was avoided. A second explosion, ten times more powerful than Hiroshima, which would have wiped out half of Europe.”

Yes, you heard that correctly. They claim that a  150 kiloton nuclear detonation could have happened. See below, for what I think of that.

0:34:00 – 0:35:00

The ensuing chain reaction could set off an explosion, comparable to a gigantic atomic bomb.

“Our experts studied the possibility, and concluded that the explosion would have had a force of three to five megatons. Minsk, which is 320 kilometres from Chernobyl, would have been razed, and Europe rendered uninhabitable.”

A 3 to 5 megaton nuclear detonation.

I apologise for putting this bluntly, but there’s only one thing I can say to that. What complete and utter bullshit.

They trump out the nuclear weapon explosion stock footage and everything. This is quite possibly the most blatantly shameless, ridiculous, completely falsifiable and utterly ridiculous example of shameless and absurd anti-nuclear-power propaganda I have ever seen.

Written by Luke Weston

May 8, 2008 at 3:27 pm

Follow

Get every new post delivered to your Inbox.

Join 72 other followers