IGottaWearShades1445 karma2012-09-23 22:53:34 UTC
Nuclear power is one of the safest (if not the safest) form of generating electricity. Nuclear gets a bad rap because most people don’t understand how it works and because fear of the unknown is a very real thing. Most nuclear reactors (Chernobyl excluded) are designed so that they become less reactive as they heat up, meaning that the “runaway” accident that you always hear about (where the reactor cannot be shut down and burns a hole through the concrete containment) could never happen - the reactor would shut itself down before anything reached an unsafe temperature. Chernobyl was not designed this way because it was made principally to produce plutonium for the Soviet weapons program. I live about 200 miles downwind from a nuclear power plant in the US, and I don’t worry about it at all.
Reactor designs are getting safer and safer, and there’s an emphasis today on designing reactors that are passively safe (meaning that no reactor operator action or external power is required to shutdown the reactor safely during an accident scenario). Even without this focus on passive safety the track record of nuclear is pretty good when compared to other forms of generating energy. Nobody died from Three-Mile Island, and I doubt anyone is going to die from Fukushima. Estimates on the death toll from Chernobyl vary greatly - some people say it was around 50 deaths, and some say it was on the order of 1000.
It’s also important to keep risks in perspective. 1000 people die every year from falling down stairs - is that an unreasonable risk? Absolutely not. ~30,000 people die every year from the particulates that are released from coal power plants. (See link below). The chances of a major radiation release from a US nuclear plant within the next year is on the order of 0.1% based on NRC estimates. Nuclear power has killed zero people in the US and no more than thousands internationally (from Chernobyl) over the past 30 years, which makes it one of the safest viable sources of base-load power. A comparison of the risk associated with each form of generating electricity is available at:
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IGottaWearShades292 karma2012-09-23 22:38:49 UTC
Zero above background - I work in an office. The background dose in America is usually around 300 millirem/year, although it can vary by a factor of 2 or 3 depending on where you live.
IGottaWearShades279 karma2012-09-24 00:09:52 UTC
Nuclear power really doesn't make that much waste. Here's a picture of all of the waste (it's inside of those big concrete casks) that was generated by the Maine Yankee Nuclear Plant during its 25 year lifetime. During this time the plant produced the majority of Maine's electricity (source: Wikipedia). For 25 years of energy, that's not much waste.
Nuclear power doesn't make very much waste because the fission reaction is so energy dense. One fission reaction releases ~200 million eV of energy and one coal combustion reaction releases ~4 eV of energy, which means that you need 50 MILLION combustion reactions to release as much energy as one fission reaction. Nuclear power plants are only refueled once every 18 months (and even then they only replace 1/3rd of the core). There's a coal plant not far from my parents' house and it needs to be refueled almost every day, and I've had the pleasure of being stuck at the railroad tracks while the 93-car train delivered the daily supply of coal to the plant.
Opponents to nuclear like to propagate the image that nuclear plants make gobs of waste, but that simply isn't true. The Yucca mountain repository (which is designed to hold 30 years of USA nuclear waste (and nuclear power generated 20% of the USA's electricity during that 30 year period) ) is only about the size of a football field.
Furthermore, you can reduce the volume of nuclear waste by 90+% if you reprocess the fuel, which I'll discuss in another post...
IGottaWearShades260 karma2012-09-24 01:26:23 UTC
Very far away. There are fundamental materials limitations that make the future of fusion power a dismal one. The typical fusion reaction (also the easiest one to get to happen) involves fusing deuterium and tritium into helium and a 14.1 MeV neutron. From a reactor materials perspective, 14.1 MeV neutrons are going insanely fast, and they do a lot of damage to fusion reactor materials.
Since neutrons have no charge, there's nothing we can do to prevent fusion neutrons from colliding with and damaging the inner wall of fusion reactors. Any operating fusion reactor would have to shut down once every 1-2 years to completely replace the inner wall of the reactor (which could in itself take 1-2 years). I doubt that any fusion reactor could be economical because of this. The fact that we also haven't hit breakeven yet (the point where you get as much energy out of a fusion reactor as you put into it), makes me very skeptical about the future of fusion power.
There are aneutronic fusion reactions that don't emit any neutrons, and I think any viable fusion reactor will run on these reactions. Unfortunately these reactions are much more difficult to achieve than D-T fusion, which makes them even farther away than D-T fusion.
Also, it should be noted that fusion isn't a magic bullet that produces energy without making any radioactivity. That 14.1 MeV neutron activates (makes radioactive) the structural materials in a fusion reactor. In fact, fusion reactors would actually be more radioactive than fission reactors; however, this radioactivity is not as long-lived as that from a fission reactor, and decays away more rapidly. Again, since aneutronic fusion reactions don't make any neutrons, they should not create any radioactivity and would not have this problem.
EDIT - I discuss cold fusion in another post farther down.
IGottaWearShades201 karma2012-09-23 21:30:26 UTC
I sent a message to the mods, I'm hoping they'll respond and then vouch for me.
An no, I've never done something like that at a party - I only order hard drinks.
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