"there seems to be something wrong with our bloody reactors today"

Reactor 3 carries out uncontrolled venting.

OK, so thanks to the commenters I grasped why the Japanese reactors were still hot despite having control rods. When you shut down, or SCRAM, a Boiling Water Reactor of the sort you find at Fukushima, there's still residual heat - because nuclear reaction products are in the fuel. These typically have short half-lives, which means they give off a lot of heat as they (quickly) decay.

When a nuclear reactor has been shut down, and nuclear fission is not occurring at a large scale, the major source of heat production will be due to the beta decay of these fission fragments. For this reason, at the moment of reactor shutdown, decay heat will be about 7% of the previous core power if the reactor has had a long and steady power history. About 1 hour after shutdown, the decay heat will be about 1.5% of the previous core power. After a day, the decay heat falls to 0.4%, and after a week it will be only 0.2%. The decay heat production rate will continue to slowly decrease over time; the decay curve depends upon the proportions of the various fission products in the core and upon their respective half-lives.

Sounds like they should cool down pretty quickly, I thought. I just hadn't realised how very powerful these beasts are. Fukushima reactor 1 (the one that went bang first) generates 439MW of electricity, and let's say it's 45% efficient (I gather that's on the high side, but it makes the mental arithmetic easier) - in other words only 45% of the heat produced gets turned into electricity, and our reactor is producing 1GW of heat.

"For this reason, at the moment of reactor shutdown, decay heat will be about 7% of the previous core power" - blimey, that's 70 megawatts. You'll burn your hand on that for sure !

"About 1 hour after shutdown, the decay heat will be about 1.5% of the previous core power." - it was I gather about 1 hour after shutdown that the tsunami struck and knocked out the cooling. Power would be 15 megawatts - or the same heat as 150,000 hundred-watt bulbs, or a 15,000-bar electric fire. Still pretty warm - you can see why the cooling would be missed.

"After a day, the decay heat falls to 0.4%" - 4 megawatts, not by any means cool.

"and after a week it will be only 0.2%" - "only" 2 million watts after a week !

Hmm. I don't know how much fuel is in the reactor, but at present, 3 days after shutdown, you've got say 3 megawatts of heat still being produced - and presumably, given the hefty shielding around the core, not being lost easily.

Uranium at 25C has a specific heat capacity of 27.665 J·mol⁻¹·K⁻¹ - in other words, it takes 27 joules of energy to raise the temperature of 1 mole of uranium atoms (say 238 grams) by one degree. Uranium melts at 1132 degrees C.

A watt = 1 joule per second.

OK, given no heat losses and a starting temperature of 132C, how much uranium could you melt in a day with 3 megawatts ?

3000000 x 24 x 60 x 60 = 2.592 x 10¹¹ joules in a day.

27,665 joules approx to raise 238 grams of uranium from 132C to melting point 1132C. Note that this assumes the heat capacity stays the same over that 1,000 degree temperature range. It probably doesn't, but we're just doing some rough approximations.

27665/238 = 116 joules to raise 1 gram of uranium by 1,000 degrees.

1.16 * x 10⁸ joules to raise a (metric) tonne of uranium to melting point.

Hmm. Given no heat losses and only uranium to melt, that looks like more than 2,000 tonnes a day ! I think a reactor has more like 50 tonnes in it. My maths may be awry, but if it ain't it certainly looks as if sans cooling a meltdown is not only possible, but likely.

UPDATE - apparently (thanks dearieme) the fuel is uranium dioxide, which has a higher MP (2865C) and a higher heat capacity of (approx - see above, the capacity varies with temperature) 85 joules per mole per degree. 270 grams per mole, 85*2600/270 to raise 1g from 265C to melting point. That's about 8.18 * x 10² joules to melt a gram, 8.18 * x 10⁸ joules for a metric tonne. One day's heat output at 3 Mw is still enough to melt about 250 tonnes of fuel.


UPDATE - reactor 2 goes pop. That's 1, 2 and 3 all had explosions. Those poor engineers must be sweating. Where's the nuclear Red Adair ?


UPDATE2 - the title is of course from Admiral David Beatty -

"It was at Jutland, after two British battlecruisers had blown up, that Beatty made his famous remark, 'There seems to be something wrong with our bloody ships today, Chatfield'"

China - Genius Genes, Gentlemen and State Power

As I said a while back, if China can set up a eugenic policy for a few Olympic basketball medals, what might they not do for a few more Nobel-winning scientists ?

Some of the world's fastest supercomputers are being set up in Hong Kong to address the age-old mystery of human intelligence.

The study of intelligence quotient (IQ) is being conducted by BGI Hong Kong, [formerly] known as the Beijing Genomics Institute. It will survey DNA samples from 1,000 child prodigies from China's best high schools, comparing them with samples from 1,000 children of average intelligence, searching for genetic variations.

The study will examine protein coding genes of the extremely smart children, many of whom are expected to enroll at Harvard, Yale or Cambridge. The results will be correlated with each youngster's school test scores, in hopes of learning how specific genetic variations affect intelligence.

The study, which started in 2009 in Shenzhen, is moving to a new facility in Tai Po. By the end of this month, 115 of the world's fastest sequencers - the HiSeq 2000 - will have relocated to the city. They will be able to sequence the equivalent of 1,000 human genomes a day, and soon surpass the entire sequencing output of the United States to become the world's largest sequencing centre.

The study by BGI, which receives strong financial backing from the Shenzhen and mainland governments, will be the largest-scale examination of its kind. Ethical and privacy concerns have hindered such work in America and Europe.

You can say that again. When a decent and humane sort like Charles Murray gets called a Nazi and a racist for writing about IQ, the likelihood of a Western government sponsoring a massive IQ/genetics research program ain't terribly high.

BTW, I'm no expert, but mightn't it be more productive to compare exceptional children with their less brilliant siblings ? I'm sure Professor Hsu knows what he's doing.

Ever since Nazi Germany misused science to support its murderous racist and anti-Semitic theories, Western societies have been extremely sensitive about linking genetics to IQ.

Yup. Even though we ain't German and we ain't Nazis, no one wants to be branded by association - which is what UK lefties will do the moment the subject's raised. But China doesn't seem to have a great deal of liberal guilt about such things - they're more into 'what works'.

Be interesting (as in the apocryphal Chinese curse) to see what comes out of this. East Asians are already among the cleverest people in the world as measured by IQ. If they could find some way of turbocharging that ... on the other hand the simplest thing would be to drop the one-child policy for clever girls.

(In the UK the cleverest girls have the fewest children - dysgenics rather than eugenics).



UPDATE - a vision of the future ? via Professor Hsu, Mark Lilla at New Republic on the two Westerners influencing bright young Chinese - Leo Strauss and Carl Schmitt.

I had heard that Strauss was popular there, as was, to my surprise, Carl Schmitt, the Weimar anti-liberal (and Nazi - LT) legal theorist... Strauss and Schmitt are at the center of intellectual debate, but they are being read by everyone, whatever their partisan leanings; as a liberal journalist in Shanghai told me as we took a stroll one day, “no one will take you seriously if you have nothing to say about these two men and their ideas.” And the interest has little to do with nationalism in the nineteenth-century sense of the term. It is a response to crisis—a widely shared belief that the millennia-long continuity of Chinese history has been broken and that everything, politically and intellectually, is now up for grabs.

... Liberal thought, the young ones now feel, just doesn’t help them understand the dynamics of Chinese life today or offer a model for the future. For example, everyone I spoke with, across the political spectrum, agrees that China needs a stronger state, not a weaker one—a state that follows the rule of law, is less capricious, can control local corruption, and can perform and carry out long-term planning. Their disagreements all seem to be about how a strong state should exercise its power over the economy and how its newfound power should be exercised in international affairs. Similarly, there was complete consensus about China’s right to defend its national interests, just differences over what those interests are. When my turn to talk about American politics came, and I tried to explain the Tea Party movement’s goal of “getting government off our backs,” I was met with blank stares and ironic smiles.

That makes sense to me. Chinese national interest demands better governance, not less government. The national interest is expressed by Schmitt :

Classical liberalism sees society as having multiple, semi-autonomous spheres; Schmitt asserted the priority of the social whole (his ideal was the medieval Catholic Church) and considered the autonomy of the economy, say, or culture or religion, as a dangerous fiction. Classical liberalism treats sovereignty as a kind of coin that individuals are given by nature and which they cash in as they build legitimate political institutions for themselves; Schmitt saw sovereignty as the result of an arbitrary self-founding act by a leader, a party, a class, or a nation that simply declares “thus it shall be.”

... The Chinese tradition of political thought that begins with Confucius, though in a way statist, is altogether different: Its aim is to build a just social hierarchy where every person has a station and is bound to others by clear obligations, including the ruler, who is there to serve. Central to the functioning of such a state are the “gentlemen” (or “gentry” in some Confucius translations), men of character and conscience trained to serve the ruler by making him a better one—more rational and concerned with the people’s good. Though the Chinese students I met clearly wanted to épater their teachers and me by constantly referring to Schmitt, the truth is that they want a good society, not just a strong one.

And the better governance comes from Strauss's gentlemen :

Taking a cue from Aristotle, Strauss distinguished between philosophers, on the one hand, and practical men who embody civic virtue and are devoted to the public good, on the other: While knowing what constitutes the good society requires philosophy, he taught, bringing it about and maintaining it requires gentlemen. Aristocracies recognize this need, democracies don’t ... But for the young Chinese I met, the distinction between sages and statesmen and the idea of an elite class educated to serve the public good make perfect sense because they are already rooted in the Chinese political tradition. What makes Strauss additionally appealing to them, apart from the grand tapestry of Western political theory he lays before them, is that he makes this ideal philosophically respectable without reference to Confucius or religion or Chinese history. He provides a bridge between their ancient tradition and our own. No one I met talked about a post-Communist China, for obvious reasons. But students did speak openly about the need for a new gentry class to direct China’s affairs, to strengthen the state by making it wiser and more just.

Now this is all fascinating stuff, implying a future China a little like Victorian Britain, with an elite class of gentlemen born (or bred) to rule in the national interest. But the British were always sceptical of ideology, let alone an ideology like Schmitt's, with its theory of 'the enemy' or 'the other', not to mention a love of dictatorship and 'decisive action'. Schmitt considered the Night of the Long Knives to be "the highest form of administrative law" - not a guy you'd want to be up in front of in court.

When I see people like Andy Newman worshipping at the People's Shrine, I do wonder - is he just making his obeisances to whatever rising power isn't British (hedging his bets by also backing Islam), or is he genuinely confusing some idealised Socialist Republic in his skull with the reality of the PRC ? What I see in these young Chinese patriots is a desire for something more like the "ancient virtues of courage, patriotism and devotion to duty" which Glubb Pasha describes in a rising empire.

“Chinese tradition has many good things, but we’ve ditched them,” Wan told me. “I feel there have to be people to carry them on.” She came from a middle-class home, and Tang’s humble roots and old-fashioned values impressed her. “Most of my generation has a smooth, happy life, including me,” she said. “I feel like our character lacks something. For example, love for the country or the perseverance you get from conquering hardships. Those virtues, I don’t see them in myself and many people my age.”

Those who came into conflict with Victorian Britannia usually came off worse - she was pretty robust about defending her interests. How robust will a 'Schmitt-powered' Chinese elite be?

Nature Vs Nurture (Again)

Pop psychologist Oliver James plumps for the Blank Slate, the whole Slate, and nothing but the Slate in the Guardian - with a topping of political partisanship :

Politics may be the reason why the media has so far failed to report the small role of genes. The political right believes that genes largely explain why the poor are poor, as well as twice as likely as the rich to be mentally ill. To them, the poor are genetic mud, sinking to the bottom of the genetic pool.

A commenter writes :

Please Guardian people - get a geneticist to respond to this article

And as if by magic appears one Bob O'Hara on the Guardian's Science Blogs :

During one of my frequent breaks, I saw this twitter comment, from Mark Henderson, science correspondent at The Times:

Oliver James demolishes another straw man...
http://bit.ly/aTuMlX

A couple of minutes later, when I took my next break, I followed the link. Henderson was only sort-of accurate about Oliver James demolishing a straw man. If you know anything about the subject, it was clear that he wasn't even attacking the straw man he was setting up: he was tilting at a windmill that he mistook for the straw man he had set up.

James' Comment is Free piece resurrects the straw man of the old nature-nurture debate. Is human behaviour determined by genes or by the environment? We've pretty much answered this: "it's more complicated than that". Both genes and environment have an effect, and it's going to be messy (genes can change susceptibility to having a psychiatric disorder, but growing up in a bad environment will make it more likely that you will actually suffer from psychiatric problems). The interesting genetic questions surround the relative importance of different genetic and environmental effects, and finding the genes that are involved in genetic disorders.

What's really scary are the comments on James' piece. The Blank Slate is a religion, and any deviation from it is the heresy of evil people :

" ...any child at school knows that some people are sh*ts and some aren't; there's rarely any particularly clear reason for this. And if you are, you're likely to become a right-winger, because the political right endorses your character defects and cruelties of nature; it provides a justificatory ideology which encourages you to play out your sadism and cruelty.
Rightwing politics dont make people nasty:- nasty people support rightwing politics! Eureka!

PS:- why are there so very, very few Ciffers from the left, prepared to post in the two rightwing broadsheets? Why are you prepared to let the right crow triumphantly from on top of it's dunghills in the Times and Telegraph? They're not only nasty people, on the whole; they'e often really, really dense; go on, expose them for what they are:- stupid, malicious people bereft of human decency."

Or how about :

Right-wing authoritarian followers prefer to see the world in stark black-and-white. They conform closely with the rules defined for them by their authorities, and do not stray far from their own communities. This extreme, unquestioning conformity makes them insular, fearful, hostile to new information, uncritical of received wisdom, and able to accept vast contradictions without perceiving the inherent hypocrisy… Conformity also feeds their sense of themselves as more moral and righteous than others…

I presume that unimaginative insular parents produce unimaginative insular children however wouldn't it be great if it was down to a faulty/missing gene that could be fixed because I honestly believe that the human race can not evolve further until we can fix them.

Brrr !! That Theodore Adorno (and the people still teaching him at Uni) have a lot to answer for.

Any Chemists or Physicists Out There ?

My daughter has a question - and not a bad one, either.

When a radioactive substance decays by alpha emission (I told you she was precocious) , the alpha article is a helium nucleus i.e it has no electrons and a positive charge of 2.

What's left has lost two protons - so its atomic number is two less and it's a new element.

Here's uranium decaying to thorium :


Uranium has 92 protons (and hence 92 electrons), thorium has 90 protons and hence 90 electrons.

Her question is - if the uranium fires out an alpha particle, what happens to the 2 surplus electrons left on the thorium atom ? It's now got 90 protons (having lost 2 in the alpha particle) but still has 92 electrons.

Answers on the Web are :

Health Physics Society :

It is possible that the two excess electrons associated with the thorium could find their way to the alpha particle and neutralize it, but this would likely not be a one-step process, since the alpha particle is emitted with appreciable velocity and moves some distance away from the decay site before coming to rest. More likely excess thorium charge is transferred to some other atoms or molecules in the system; eventually the alpha particle is neutralized as it picks up two available electrons to yield a neutral helium atom, and charge remains conserved.

Physics Forums :

When the U (Z=92) transforms to Th (Z=90) as a result of alpha decay, the two electrons are lost to the nearby medium. The decay nuclide is like surrounded by similar material, or if at the surface of a solid, it is in contact with air or some gas. Likely though the alpha particle rips away some electrons on its way out of the nucleus, but those electrons are quickly recaptured.

As charge particles (alpha and beta), and even gamma rays, pass through material, they interact with atomic electrons and excite or ionize atoms (hence the term - "ionizing radiation"). The range of an alpha particle in solid material is very small - on the order of microns, so it does not travel far from the nucleus from which it originated. Because it has a +2 charge, the alpha particle will ultimately attract two electrons. There will be an effective net migration of 2 electrons along the path the alpha particle took while slowing down.

Advanced Physics Forums :

It's an interesting question that whether the atom of the new element now have a negative two charge or does something else happen to these electrons. Electrons are not exactly static charged particles. They have a good deal of fluidity in practice, and in fact one could go as far as saying that they are inherently fuzzy objects, like a photon of light. In most solids (and even in gases) any non-equilibrium electronic state is almost instantaneously readjusted. It's rearrangements of atomic nuclei which take time (so that, while chemical reactions technically involve only electrons, any reaction which requires movement of whole atoms will have a measurable rate). Essentially what happens in a-decay is that the a-particle knocks electrons loose from one or more nearby atoms, then picks up two of the loose electrons to form a neutral helium atom. Meanwhile, the other surrounding atoms (including the "dianion" parent atom -- the scare quotes are deliberate) very quickly reshuffle their electrons in order to have the most energetically stable configuration. This reshuffling energy, by the way, shows up as heat; strong a-emitters like radium are typically a little warmer than their surroundings, and radioactive decay is a prime source of the earth's internal heat. Hope this answers your query.

So while the answers make sense in terms of charge conservation, they're all a little vague on the actual mechanics. Does the thorium atom spend time as a thorium ion ? Are the electrons lost by the thorium atom to spend time as free electrons, or do they immediately attach themselves elsewhere ? Or does that depend on what kind of atoms or molecules are around for the elecrons to attach to ?

And a question from me - at any time, how many ions or free electrons are around, say in air ? If you drew a virtual metre-square box in your living room, what proportion of the molecules therein would be ionised ?