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matt

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words matter: on numbers and scale [Mar. 18th, 2011|05:37 am]
matt
http://www.bloomberg.com/news/2011-03-18/japan-unit-4-pool-s-heat-exceeded-three-times-normal-iaea-says.html

There's a lot of heat coming out of the disaster in Japan, and it can be really difficult to wrap your head around some of the numbers and the scale involved. As one news commentator I recently heard say: "Words matter".



Particularly, words like "plume". No one wants to hear a plume of radiation is headed toward California, no matter what your political persuasion. But you can have a "plume" of moisture- in other words, rain, or other weather, and just like a minor schvitz is different than a category 5 tropical storm, it's all about making sure you put scale on the story.

I'm calling out the above URL, mostly because they state that 84 degrees C exceeds three times that of 25 degrees C. Literally, as a scalar value, 84 > 25 *3, but is that a meaningful statement?

Because in Kelvin, 357K is not greater than 298K * 3. Now, if I rewrite the above as such, you could rightly argue that I'm minimizing the threat posed by such a dramatic increase in temperature, and surely, that is not my intention. My point is to make you both more and less nervous, and to get you thinking about ways in which you can think more critically about the information you are given.

The boiling point of water is 100C. Now, in mm of mercury, the pressure of water at 100C reaches the same as the atmosphere (760mm), and the partial pressure of water is an indication of how fast water can evaporate from a surface. Clearly, the problem of evaporation of the water from the cooling ponds is one of the biggest concerns, and the partial pressure of water at 25C is 23.8mm, and at 84C is 416.8mm. So, if you wanted to talk about the risk of evaporation from the pond, 84C is over 17 times greater than 25C.

Now, hold on a minute. I used to do kinetic studies, which is just a way of saying that I studied the rate of chemical reactions. There's some complicated math involved, but because the math is complicated, it's easy to make mistakes. One of the rules of thumb I was given to help reality-check my calculations is that for a 10 degree C increase in temperature (relative, valid for both kelvin and centigrade, or 18F) that the rate of a reaction roughly would double. So 84 - 25 ~= 60, so doubles 6 times, 2 ^ 6 = 64, so 84 degrees C is something like 64 times 25C when talking about reactions.

So, is that temperature 3 times greater, or is it only fractionally greater (in kelvin), or is it 17x, or 64x greater? What does that number actually mean?

The point of this note is not to get you worried, it's to force you to begin to question what you read, are told, hear. Not in a "I'm Glen Beck, let's question evolution and call for the end of times" kind of way, but to make you realize that all people, including myself, have a vested interest in causing you to sympathize with one viewpoint or another. If you are fond of freedom and democracy, it is your responsibility (you are accountable!) for educating yourself and cutting through the crap that you are told to make an informed, responsible decision for yourself.

The vast majority of what you are being told, both in the "panic!" camp and the "no worries!" camp, are cleverly disguised half truths. There is only one proper response to a crisis, and that is to shelter in place unless there is an immediate danger, and to gather accurate data for decision making.

http://www.snopes.com/photos/technology/fallout.asp

http://www.nytimes.com/interactive/2011/03/16/science/plume-graphic.html?ref=science

If you want to scare yourself, there's certainly people willing to enable you- the Snopes article above is illustrative. But even well reasoned and informative data like the NY Times article above can be used for panic or platitude depending on how biased for or against radiation and nuclear power you might be. I'm not going to snow you- while I retain some skepticism, I believe that there are numerous appropriate applications for even highly dangerous technology like nuclear power, and I believe that knee-jerk banning of the technology is unwise. I do believe that some level of market-based though regulated use of nuclear power (free of distorting incentives) is prudent, even as a "radioactive plume" is headed my way.

Could Tokyo Electric have done things better? Yes. Will there be mistakes? Yes. Is that any consolation to the people surrounding Fukushima? No, and I'm not intending to make the decision for Japan, or anyone else, just revealing how I might vote if that matters to you. Might I feel the same way if we were talking the Diablo Canyon plant (http://en.wikipedia.org/wiki/Diablo_Canyon_Power_Plant )? I'd like to think so.

We've had about a century of experience with the existence of radiation ( http://en.wikipedia.org/wiki/Henri_Becquerel ) and there are many who would like to put the genie back in the bottle. The history of radiation has a very checkered past- from radium patent medicine and radiation "cures", through the dawn of the atomic era, and post Chernobyl. Even in the countryside of Chernobyl, life goes on post-people.

While I am not worried, I am resentful that more effort is not made to measure radiation and make it more intelligible and meaningful. It's difficult to understand, because it's more than just the straight-line emitted radioactivity but also the dust and particulates which have a life cycle and emission pattern of their own. Many have aptly recognized that even coal fired plants emit toxic heavy metals and radiation because the dilute particles become concentrated when you "burn away" the majority of the carbon fuel.

http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste

The radioactive plume emitted by a coal fired plant may even exceed that of nuclear, if I read the above link correctly, but this too I take with a healthy dose of skepticism. You will find that most people have their own little "Pascal's Wager" with nuclear energy, that while the benefit might be small, the potential consequence is too terrible to consider rationally. Well, that's bullshit, we all need to take the emotion down a notch and try to consider it rationally, because like it or not, the cat is out of the bag.

What is true is that without accurate measurement, we cannot see the direct consequences of our actions. Look at your power bill and your power company's website, and you can, with some great degree of effort, convert your kilowatts of use into some measurable amount of radioactive emission (or heavy metal emission), and be accountable for your usage of power and resource.

What's even easier? Turn off the lights when you leave a room. Buy energy efficient appliances. Insulate your home. Drive 55mph instead of 70. This advice is just as true today as when I first heard it thirty years ago. These are real things that reduce your energy footprint, and help reduce the need for more power plants of all types, nuclear or conventional. These are things that don't directly help the people in Japan, but are real things that you can do to help everyone be less of a victim of the future.

Think rationally and creatively, and you honor the memory and bravery of the people of Japan.
LinkReply

Comments:
[User Picture]From: nightspore
2011-03-18 12:47 pm (UTC)
Nice. (The insulation of the home thing, though, isn't clear cut. You need to do a radon check first. The better insulated the home, the more the potential radon exposure on the ground floor.)
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[User Picture]From: hbergeronx
2011-03-18 01:01 pm (UTC)
Agreed. I don't want people to blindly follow anything, even if I turn out to have the best answer.

I've had people argue with me on all of my recommendations. One of my co-workers once argued that the 55mph thing is B.S, that modern vehicles are geared more efficiently and that 70 mph is just as fuel efficient. I argued that he had never measured it for his particular make and model, and couldn't answer such a question with the data provided from any given manufacturer, and *that* was the true crime. I argued the most fuel efficient, barring "off" or "steeply downhill", was where the gas pedal was depressed least on a flat road in any gear, so there might be multiple "optimal speeds". But if you've ever coasted while on a totally flat highway, you know intuitively in any car that it is not naturally 70 mph.

My co-worker was an otherwise highly intelligent, rational person. Which goes to show that irrationality is an extremely prevalent disease.
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[User Picture]From: st_rev
2011-03-19 12:25 am (UTC)
Good analysis. Pointed people at it.
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From: boderama
2011-04-08 08:37 pm (UTC)
I don’t bookmark sites but i will bookmark this! LOL!

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(Deleted comment)
[User Picture]From: hbergeronx
2011-11-01 04:33 pm (UTC)
I'd be happy to follow up on this- what interested you about the post? What would you like to see written about?

also: http://spectrum.ieee.org/energy/nuclear/24-hours-at-fukushima/0
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