Tuesday, March 22, 2011

Nuclear Power: Fiction, Fear and Facts

If you've been reading or watching the news, you've probably been hearing a whole lot of information about the Fukushima Nuclear Power Plant in Japan.

And how the recent earthquake and tsunami have combined to turn the above scene into a potential disaster.

At present, however, contamination has been minimal, and the damage -- thus far -- has been practically zero.
What do I mean? Let's explain -- in the simplest terms possible -- how radioactivity works. In order to understand it, we need to go inside the building blocks of matter -- atoms -- to their very cores.

The nucleus of atoms contain over 99.9% of their mass, and are made up of neutrons and protons. The number of protons determines what type of atom you are; for example, hydrogen has one proton, and is the first atom. But you could have different numbers of neutrons and still be hydrogen! Hydrogen actually has three different known isotopes, depending on whether it has zero, one, or two neutrons.

And while hydrogen and deuterium are stable, tritium is not, which means it's radioactive! And radioactive materials emit radiation of three different types: alpha, beta (which is the case for tritium), and gamma radiation.
And these three types of radiation do damage when they penetrate living tissue. What can they each penetrate?
Well, alpha radiation is the least damaging; a single sheet of paper (or the top layer of dead skin cells on the human body) is enough to stop it. Normal (unenriched) uranium gives off alpha radiation, and basically the only way to harm yourself with alpha radiation is to eat it, which is famously how Alexander Litvinenko was murdered, and how this drastic change (below) happened over the course of about three weeks.

Beta radiation is a little worse, and requires about a centimeter of wood, plastic, or a thin sheet of aluminum to stop it, but by far the most dangerous type of radiation is the high-energy gamma radiation.
Believe it or not, the human body actually, naturally, contains trace amounts of radioactive elements such as uranium and thorium. That's why encountering another human being will actually expose you to a small amount of radiation!
(Image credit: Ellen McManis, an undergraduate across town from me at Reed College.)
The "unit" that we measure radiation in humans in is a Sievert (Sv), and it takes a dose, more-or-less, of about whole Sv over the course of a year (or less) in order to do some real damage to a human being. Note how even the largest dose in the chart above, for a professional radiation worker, is 50 milliSieverts, or just 5% of what it would take to damage you.
Well, Randall of XKCD has created a beautiful chart showing just how much radiation came from nuclear "disasters" throughout history, including the present one in Japan. Here are some screen captures.

So, each daily dose for an "average" person very close to Fukushima is just 3.5 microSieverts, or less than what the "average" person in the middle of nowhere receives on a daily basis.
And if you look up the maximum level of radioactivity from Fukushima so far -- at the two sites 50 km NW of the plant -- here's how that compares.

First off, note that Three-Mile Island, the previous record-holder for second-worst nuclear disaster in history, was less bad for the worst person experiencing it than getting a mammogram is. And the worst dose anyone near Fukushima received is just 0.0036 Sieverts, or an amount you'd have to receive every single day to have anything to worry about.
It would seriously take a Chernobyl-style disaster to cause people to die from radiation poisoning, which is a gruesome way to go.
So -- some of you have emailed me -- if radiation is so bad, what's the deal with Ann Coulter?

Radiation is awful for human beings. Awful, terrible, and destructive to life, the only reason we ever treat anyone for anything (like cancer) with radiation is because we hope the radiation kills it faster than it kills you.
You want improved health because of radiation? Your only hope is to go live in a comic book Universe.

We have lots of good reasons to be appropriately afraid of nuclear physics, radiation, and radioactivity. The problem with energy and the environment -- as I see it -- is that we aren't afraid enough of coal, oil, and natural gas, all of which are worse for the environment than nuclear. But nuclear energy still has its problems, and a big one is that, if that 9.0 earthquake actually had its epicenter on the Fukushima reactor, we just might be talking about another Chernobyl.
But if I were in charge, and I had my choice of how to power the world, what would I do?


(Image credit: Sun Power Corp.)
Rather than considering it a "pipe dream" like our beloved Homer Simpson, let's take a good look at what solar panels are actually out there. The best ones can get about 19% of the incident solar energy converted into electricity. At sea level, that means about 19% of 700 Watts for every square-meter of solar panels we have.

See the "A" on the map above? Make a solar array about that size -- 35 miles by 35 miles -- and you can power the entire United States. Period. Day or night, winter or summer, rain or shine. No emissions, no pollution, no risk of radiation, no dependence on oil, coal, gas, no damage to the environment.
And if we did it -- if we invested in it and made it happen -- I think it would fix a huge number of our domestic problems: the economic ones, the employment ones, the manufacturing ones, etc.

How to make it happen? I wish I knew. We live in a world where Ann Coulter is on television telling people that radiation is good for you, and the informed citizen with a Ph.D. in theoretical physics has a blog with a few thousand readers on the internet. All I can do is hope that someone with the power to make it happen reads this, listens, and acts. We can all hope.

Ethan Sieget in Scienceblogs. More Here.

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