Since Wunelle has provided such a warm welcome (and set the bar rather high) I figured I ought to make my debut with something big. And, as Wunelle says, I'm a 'Physics guy' and that ties right in with this.
This month marks the 20 year anniversary of the nuclear power plant explosion at Chernobyl. Greenpeace is busy taking this opportunity to use that disaster to crusade against nuclear power. I think that what Greenpeace is saying about the terrible consequences of that disaster are largely accurate - many people were killed as a direct consequence of that event, and many many more have had to suffer serious medical problems as a result.
However, Greenpeace is wrong when they use this accident as an example of why we must not use nuclear power. On the contrary - nuclear power is our best available option, especially in light of environmental issues.
When you look at the options we have for supplying the power that we all use, there are not very many environmentally friendly options that are up to the task. Solar, wind and hydro power are all great, but they will never have the capacity to meet the demands for power. Hydrogen is big lately, but hydrogen is not a power source (there aren't reserves of it stashed away somewhere), it is a power storage and transport medium, like a battery. Our current choices - coal, oil and gas are bad for the environment, and some day we will exhaust the supply. That leaves nuclear power.
I am not the only person outside of the nuclear industry who thinks this way. In fact, the founder of Greenpeace (Patrick Moore, who is no longer associated with them) has come out very publicly in favor of nuclear power specifically for environmental reasons. Moore does a good job covering the pros and cons of nuclear power, but he doesn't address one the of biggest problems of the nuclear power industry - its bad public image. Nukes scare lots of folks, and it is easy to make the case that they are exceedingly dangerous and have no place in our safety-craving world. Some folks are worried about the vast amount of energy released in nuclear reactions and others fret about all of the radiation, but I think that most of that fear originates in ignorance. People just don't know much about nuclear power and readily believe propaganda demonizing it.
Here is the simple way I view nuclear power and how it really is much better for all of us than the alternatives:
The first step in the process is to collect a lot of uranium ore. This is probably the least environmentally-friendly part of the whole process, as it usually involves large-scale mining operations, and those can leave pretty big scars. However, because there is so much energy available in nuclear reactions we don't really need to keep much of that ore, and so the vast majority of it can go right back where it came from. Compare this to coal, where HUGE quantities are hauled away to be burned and the net is a big win for nuclear.
The next step in the process is to sort through the uranium and keep the tiny fraction of it that is the right form to work in a nuclear reactor. This uranium is radioactive by nature - we do nothing to produce it or to make it radioactive - we just collect what we can find. This is the process referred to as 'enriching' and it is pretty tough to sort out just the desired uranium. The difficulty of this step is what keeps the small-time players out of the nuclear game.
Enriched uranium is quite radioactive, which just means that it is in the process of decaying via nuclear reactions. These reactions release energy as a by-product of the reaction, so the uranium emits a variety of particles that carry that energy away. That is all it means to be radioactive, and we are constantly exposed to very small amounts of radiation all of the time from traces of uranium and radon that are found in pretty much all rocks (not to mention the radiation streaming to us from sources in space, like the Sun).
This enriched uranium is then made into fuel for reactors by mixing it with materials that work to stabilize and control the pace of the reactions. The energetic particles that are emitted during a nuclear reaction can trigger a reaction in other uranium atoms - hence the 'chain reaction' of a nuclear explosion. By mixing the uranium with materials that absorb these particles it is possible to make the reactions proceed at a moderate pace. The result is a fuel rod or pellet that gets hot and stays that way for a long time.
Place a few of these hot rods or pellets in water, make the water boil, run the steam through generators and you've got a nuclear power plant.
It is actually very cool when you think about it - rather than digging up vast quantities of combustible materials and then burning them to release a small amount of energy (all the while dumping all of the exhaust into the air) we can just collect some special rocks that are naturally hot and use that heat to make electricity.
This is obviously a gross simplification, but in general it is the way nuclear power works.
After the uranium has sat around reacting for a while it is no longer useful as a fuel (some of the uranium has turned itself into other elements) and so we get to the next big problem with nuclear power - the waste. What to do with the waste is a big problem, not because it really is all that terrible, but because we as a people are unable to manage risk in a rational way.
The material that we need to dispose of from nuclear plants is just the same uranium and its reaction by-products that we dug up in some mountain. The problem is that while it was in the mountain it had been put there by nature and nobody could be at fault for the harm that it might cause someone nearby (plus it was spread pretty thin). Once we have dug it up and want to get rid of it we are now responsible for putting it somewhere and whatever happens is someone's fault. A sensible thing to do with it might be to mix it in with the tailings from the mining operations and put it back in the mountain where we got it in the first place. But that would be viewed as 'contaminating' the mountain, even though the stuff was all there in the first place.
All in all though, it is as close as we are going to come to a power source that is harmless to the environment.
Finally, I do have to address the very real issue of the sort of disaster that happened at Chernobyl. It's not acceptable to say that nuclear power is great for most of us but terrible for those unfortunate enough to suffer through its problems. The disaster in Chernobyl was not a calculated risk of using nuclear power, it was a consequence of poor design and misguided desires. We don't have to do things they way they did at Chernobyl to get nuclear power. Choices were made there to extract maximum energy at minimum expense, and the reactors were too much like bombs that they hoped to control. We can do it right and when we finally do we'll be well on our way to doing much less damage to our planet as we type away on our computers (and more).
And like Wunelle, I promise puppy pics in the near future (a little pastry as compensastion for the huge pile of salad you just digested).