This is Your Brain On Awesome Thoughts on the world from a student of the mind

28Mar/11

Nuclear power in a nutshell

With all of the media coverage going on right now about the disaster in Japan, perhaps a bit of explanation is in order. (Warning for those of you versed in the world of nuclear physics: this is going to be a relatively simple, watered-down, and incomplete idea of what goes on in a nuclear reactor...don't get mad at me!) And let me get something out of the way right from the get-go: there's not going to be a nuclear explosion in Fukushima, Japan. While atomic bombs and nuclear power plants both rely on nuclear reactions, they are extremely different when it comes to their potential to explode.

Schematic of a simple nuclear reactor like the ones in Fukushima

So here's the short version. Essentially, nuclear reactors work in the exact same way as certain other engines we've been using for hundreds of years: by using steam. At the heart of a nuclear reactor lies a chamber that is submerged in large tank of water. Inside this chamber are a number of uranium "cores," if you will. These are about the size of a Tootsie Roll, and they're totally awesome.

Why are they awesome? When the reactor is in operation, each of these cores undergoes a self-propagating nuclear reaction in which uranium atoms split apart and release massive amounts of energy. Within the chamber are millions of neutrons floating around, causing this reaction to occur. The result of all this energy is a TON of heat, and since the reactor is submerged in water, this heat creates steam that leaves the chamber and powers engines. Think of the nuclear reactor as a kind of atomic furnace, burning uranium instead of wood.

So what happens when this all breaks down? You may have noticed that I said this was a self-propagating process.  That means that you can't just stop it at will. As long as there are neutrons in the uranium chamber, nuclear fission will occur. Luckily, there are two general mechanisms to control this process. One is the water that surrounds this uranium chamber. The steam that is generated by this process is constantly being collected, cooled, and then recirculated through the system. This means that (when things are working properly), there is always a pool of water to capture the heat and keep things relatively stable.

The second control mechanism is a series of rods that can be inserted into the uranium chamber. These can be made of a number of different materials, but their key function is to "soak up" the neutrons in the chamber. As you'll recall, these neutrons are what drives the nuclear reaction, and removing them will cause this process to slow down (something you want in the event of catastrophe). If you want to slow the reactor as much as possible, you insert every rod into the core entirely and at the same time. This is called scramming the reactor, and it doesn't stop the reactor; it only slows it down.

What happened at the Fukushima plant? Believe it or not, the reactor held up to the earthquake just fine. All of the proper safety protocols were executed, and things seemed to be OK. However, safety engineers weren't prepared for a giant tsunami, and when key components of the power plant's backup electricity system were submerged in water, the reactor stopped recycling the steam that was created. As a result, two bad things happened: one was the gradual loss of the water surrounding the uranium core (since it was being turned to steam without a replacement), and the other was the increasing buildup of the steam itself.

The first is a problem because that water served as a way to carry the heat away from the uranium fuel. Without that extra cooling, the cores become so hot that they can melt. This is what is known as a "nuclear meltdown." The second (and more dangerous) problem of steam buildup arises from an interesting property of water. When steam (aka vaporized water) is heated to extremely high temperatures, it can actually cause the water molecules to break down into their component parts, hydrogen and oxygen. The important factor here is the hydrogen gas, an incredibly flammable substance that has a tendency to cause explosions. Given the super-hot temperature of the reactor, the hydrogen can explode, launching radioactive materials into the environment. In addition, if a fire is started, then smoke from the fire can carry even more radioactive particles into the air and beyond (a la Chernobyl).

We aren't sure yet what exactly happened at Fukushima, but rest assured it was not as bad as the media would have you believe. While there is a certain amount of radiation emanating from the power plant, it is far below the amount that is dangerous to humans. The situation at Fukushima could still change in a bad way, but as of now it seems that the damage has been contained. As we continue monitoring the situation in Japan, remember that this could have been a much worse catastrophe, had the proper safety mechanisms not been in place. All things considered, nuclear technology is a surprisingly safe way to get energy without carbon pollution. In the coming weeks there will be a lot of sensationalist talk about what happened at Fukushima. In light of such information, I urge you make an effort to separate fact from fiction, and as the great Douglas Adams would suggest, "Don't Panic!"

If you're still confused or curious, check out Stuff You Should Know's recent podcast on the disaster.

 

5Jan/11

An inside look into some sweet 3-D magic

Check out the above video for a really interesting look into the incredibly complex and beautiful visual effects in Tron 2.0.  An insane amount of the movie is created using computer graphics, including most of the environments, the coolest parts  of the battle scenes, and even some of the main characters.

It takes a ridiculous amount of effort and detail to come up with each scene, and this gives a pretty interesting idea as to some of the steps that are involved in bringing together a movie this visually rich and unique.  Almost equally as impressive is that some of the stunts are actually done by human beings as well, they're only enhanced for extra eye-candy dazzle.  (for a quick e-digression, here's the wikipedia article on "tricking" aka throwing yourself in the midair and twisting about as though caught in an invisible washing machine).

Anyways, I hope you enjoy this beautiful look into the underbelly of Tron.  It may be a completely fantastical view of what the inside of a computer looks like (it's also beautiful, just in a slightly less violent way), but I certainly can't complain about colorful explosions and magical flying motorbikes...

(For those of you who haven't seen the movie, you may want to hold off unless you're willing to see a spoiler or two)

27Oct/10

The phrase “ear worm” may have a very different meaning soon…

So this is a pretty short article, but I couldn't help myself from talking about it.  If you read regularly, you'll know this is because it contains two of my favorite things: lasers and brains (it's actually about brain tumors, which are certainly not one of my favorite things, but pretty amazing nonetheless).

Washington University continues to impress in the world of neurotechnology with a new method for treating inoperable brain tumors.  The need for this basically stems from the fact that, while some tumors exist near the surface of the head and are easy to remove without damaging too many important parts, others exist deep within the brain and aren't touchable without causing  massive damage and causing people to start tasting blue or something like that.

So, how do you get rid of a tumor without physically taking it out of the brain?  Well, the method devised by this team involved using the radiation from a laser to kill the cancerous cells.  This is an understandably delicate process, since it's often difficult to aim for bad cells without taking out some of the good ones, but this method attempts to deal with this problem by placing the laser as close to the tumor as possible.

How does it work?

Graphic rendition of the procedure

Basically, the doctor drills a small hole in the patient's skull (typically about the width of a pencil).  They then use MRI, a technology that allows us to look at the structure of a patient's brain, to locate exactly where the tumor is and snake a tiny laser probe through the hole and into the heart of the tumor.

Once safely nestled in its cancerous cocoon, the doctors activate the laser, which emits a blast of radiation that is just strong enough to kill its immediate surroundings, sparing the healthy tissue nearby.

This sounds incredibly dangerous, but in fact it could be a very useful technique in dealing with an otherwise medical condition.  While we know that the brain is a very delicate organ, it is also very robust, and techniques such as this one allow us to choose our path through the brain and avoid the areas that would do the most damage to the patient.

This technology isn't out in the market yet, but hopefully it'll make it through the refining and approval process soon.  Coming soon to an O.R. near you!

via PhysOrg

31Aug/10

Chummy technology

One of my buddies just sent me a link to a really interesting article on our relationships with technological devices.

Yes, that's right, I said relationships - and appropriately so, because that's just what the research discussed in the article covered: the emotional and personal connections that we inadvertently make with our inert and non-living tools.

Clifford Nass, a psychology professor at Stanford University, noticed that human beings often treat their computers, iPods, and other technological devices as though they had feelings of their own.  When they don't do what we want them to, we get mad at them...when we inadvertently break them, we feel sad...and when we use them consistently, we might even find ourselves conversing with them.

Is it really true that we can't help but form relationships with the electronic tools that we use every day?  A growing body of research suggests that it is.

For example, Nass studied the extent to which our natural tendency to form in-groups and out-groups carries over to machines.  He separated people into two groups, a green team and a blue team, and paired them with a computer that was either the same color as their team (described as a "teammate") or unrelated to their team's color.  What he found was that participants gave much more favorable reports of their interaction with the computer if it carried the same color as their team - a totally illogical yet very real phenomenon that was reproduced many times.

In another example, researchers tackled the decade-old object of my hatred, "clippy" from the Microsoft Suite.  While subjects originally reported this little character as nothing short of an unhelpful nuisance, researchers found that they could very easily alter users' relationship with Clippy in a dramatic way.  Instead of just telling you what to do, the researchers made Clippy ask whether or not his advice was helpful, and if the user selected no, he continued by berating the Microsoft corporation and suggesting that an angry letter get sent.  The result - users started to like Clippy, found him helpful.  Their anger had been turned to companionship.

These kinds of findings hold many ramifications for the real world and in the ways in which we can interact with objects of our own creation.  It seems like every day we come to rely upon machines for getting through our daily lives, and perhaps it is no surprise that we become attached to them just as we would to any being that we interact with regularly.

Without getting too "dystopian future with robots ruling us all," I'd be interested in seeing whether or not the presence of robots or computers could provide an adequate substitute for adequate human interaction.  If we act towards these machines as we would to other living things, perhaps their effects on us are similar as well.

via The Wall Street Journal