Hi all.

In university we're studying different types of power systems and generation methods and one of the more interesting types are nuclear stations.
I know where I stand on it but I'm curious as to what others think.

For, or against? Please specify why.

Too much highly radioactive nuclear waste that will pollute this earth for thousands of years. There are nicer alternatives like wind, solar, and wave energy.

Sure there are but the alternatives are in no way as power dense as nuclear. You say it pollutes the earth for thousands of years, and to some degree you are right. But consider this:

Suppose you want a 1 GW power plant. If you're using conventional steam powered stations you're going to require about 3 million tonnes of coal (about 2.1 or so of oil), to generate this power and with that tonnes and tonnes of waste is put into the atmosphere (nasty ozone depleting and global warming stuff like sulphuf dioxide, carbon dioxide, thier monoxides etc).

With nuclear you need 15 tonnes of uranium (or less depending on which process you use), and 1 tonn of waste is outputted. Now the generation of this energy doesn't produce any of the nasty pollution that oil burning does. None of it. It's 'clean'. But what it does produce (while dangerously toxic), is easily confineable and while we can't destroy it we can bury it deep deep into the earth surrounded by layers of concrete and lead and steel which makes it ... for the sake of the arguement ... clean.

I know you mentioned clean energies but the thing is nuclear is cleaner than a lot of methods and all clean energy production (so lets compare like with like), but it does not approach the necessary power densities that are required for the population demands of now, and the future. Unfortunately only fossel fuels and nuclear do that.

Also the enviornmental impact of some clean energies (I'm thinking hydro), has spectacular enviornmental inpacts. Take for example the three gorges dam. 1.2 million people were relocated for that. Think of the Hoover dam. Sure it's in a desert but before and after photos show the extent of it.

Why is power density so important? That only leads to ugly looking and dangerous high tension transmission lines all over!

Also, some of the highly radioactive waste is in the form of inert gases. Very difficult to contain for thousands of years!

I was not advocating hydro power (too limited), and read that Hoover Dam was built mostly for flood control.

>> That only leads to ugly looking and dangerous high tension transmission lines all over!
Nope. That's just power
Power density is the amount of utilisable power in a substance per unit mole of it. So the more power you can get from something the less you need. Uranium and plutonium (which can be used too), have astronomical power available (ideally 3*10^6 times that of coal, but in reality it's reduced to about 120-140 thousant times due to impurities and power losses in energy conversion).
It's like technology - the smaller it is the happier we are! We no longer need room-sized computers, for example. So why need 130,000 times the stuff to get the same?

Thanks for clarifying power density!

I need to add geothermal and bio energy to my list of cleaner alternatives.

The 15 tons of uranium you are talking about must be highly enriched uranium. The world's supply of this particualr isotope of uranium is very limited, as far as I read.

>> Also, some of the highly radioactive waste is in the form of inert gases. Very difficult to contain for thousands of years!

Well not so. You are right, of course, about the gasses, but they are confineable.
In nuclear power generation the core is sealed off from the outside completely and that's where the radioactive 'stuff' is put and made react. That stays in there for about a year and a half (depending on the process it could be more or less, but 18 months is generally a good marker), so it is only when someone is to replace the fuel that the outside is exposed to the inside of the core. However someone'd be pretty stupid just to open my hypothetical door and let it all out. There are precautionary measures after precautionary measures being taken to ensure the gasses do not leak. I believe the chamber is vacuumated, flushed again and again, all bad gasses and waste is collected and then kept under heavy water for 40 years (no exaggeration there, honest!), and then burried. The danger of it (lets not ignore it is dangerous), leads to extreme precautions.

>> The 15 tons of uranium you are talking about must be highly enriched uranium.
3% The particular isotope that we use for the more general purposes naturally occurs at 1% (but processes called fast-breeding reactors use pretty much the whole lot!), but it is enriched to 3% and then used.

>> The world's supply of this particualr isotope of uranium is very limited, as far as I read.
With current processes the current known sores of it should last about 150-200 years (a lot longer than oil), but if fast breeder reactors are used more the life span should increase by at least ten-fold.
Also, remember uranium is mined. So it's not as though we can't get more Plus about 2-5% (I can't remember the exact figure), of the waste can be processed again to extract more useful uranium and this process makes it less 'bad'.

>> wind, solar, and wave energy
Wind is good, very clean etc, but it is not reliable. It's power is as a function of the wind ... same with solar with the sun. Sure you have predominantly sunny and windy places which integrally have a steady theoretical generation rating but that doesn't mean that every day you're guaranteed to get the power you want! Some good days, some bad days. Wave is like (kinda), hydro. Well it depends on the setup really, but they can be modelled with very similar methods and equations.

>> I need to add geothermal and bio energy to my list of cleaner alternatives.
Unfortunately their respective power densities are not enough either. Sure they're clean. But not good enough at the end of the day.

>> and read that Hoover Dam was built mostly for flood control.
Yep. That's true. But still it produces 1.8 GW of energy. You can't argue that's not favourable. I was just stating some facts. A lot of people give out about visual pollution too, but I think that's a silly arguement.