Nuclear Physicist(s) Please Answer?

Question

With all this nuclear talk in the mid east I was thinking about the waste. The question that came to my mind is "What waste?". I have just finished reading Wikipeida on this and still do not have a clear understanding.

If this "waste" is so radio active, why then aren't we using it to generate electricty? Might need a different reactor than the first, but that would be ok.

So wuz up with this? Burying it or turning it into tank ammo does not make sense to me. Isn't there any type of reactor that can take this waste and generate electricty?

TIA

Except for the first bozo, I want to thank all of the rest for taking the time to educate me on this.

I did try wikipedia first. The did not understand the concept of ionization radiation to the extent needed to understand this problem. I wish I could award 10 points to all the others, however I will have to pick one of you which I will do using a random method since each answer provided me with new insight. SNAP generators with 238 is hot, but way to hot, Breeder reactors will be something I reasearch more, however I see the refinement waste is enormous.

My questions may sound stupid to you, but that is why I take the time to answer questions that sound stuid to me. Give here, receive there.

I thank you all.

I forgot to mention, I had the opportunity to go inside Indian Point 2 nuclear reactor when I was about 13 and it inspired me. However the waste problem keeps popping up as did during this Iran thingy. If only we could get our knowledge around this problem, many families would have better lives.

Answer 1

After you initially fuel a reactor with fissionable uranium and operate the reactor, the radioactive atoms gradually undergo fission and become smaller, more stable elements. Eventually, the proportion of fissionable uranium in the fuel gets small enough that it's difficult to maintain a useful fission reaction. It's no longer potent enough to fuel a reactor, but it's still to radioactive to put into your local landfill.

Fast breeder reactors are used or planned elsewhere. They produce heat for electricity but also produce more fissionable uranium than they consume, and they can use the spent fuel from a standard thermal reactor. They do reduce the volume of waste as well as produce more fuel. They are not now economically competitive, but research continues, The best choice for now is storing the spent fuel.

In spite of its drawbacks, it's still an excellent technology for power generation, and can contribute significantly to reducing our consumption of, and dependence on, fossil fuels. It's also a partial solution to the global warming problem. Alternatively, we could just let global warming run its course, and then we won't be around long enough to worry about the stored nuclear waste.

See the September Scientific American, a special issue on energy.

Answer 2

There are actually three types of waste. One is the material that is not nuclear fuel but came in contact or in close proximity with it and became radio active as a result. These are considered low level radio active wastes and can be quite bulky.

The other two types of waste are part of the nuclear fuel. One part is the uranium that was NOT "burned", or the plutonium that was formed when the U238 -- the non-fissile fraction -- absorbed a neutron. This can be reclaimed with a fuel treatment plant to produce new fuel, but it is a costly process, and some fear that the plutonium could be stolen by people wanting to do terrorist acts. The other part of the waste is the left over residue of the broken down uranium that actually was "burned", and it could be made of virtually any elements and isotopes, but most likely the elements around number 46 (half of uranium's 92; for obvious reasons, and that atom was broken in two -- although not necessarily half and half). This is a lot of different isotopes, some being more readio-active than others, and those cannot really be used to produce nuclear power. The radio activity that produces power is the one that splits atom, not the one that emits alpha, beta or gamma radiation, and this is the kind of radio active decay that the fission by-products undergo.

The depleted uranium that is used to make armor piercing ammo (and tank armor) is the left over U238 that was removed from the natural uranium, so that the U235 proportion would be increased from the natural 0.7% to reactor grade 2 to 3%. That U238 has very very low radioactivity, with a half life of 4.5 billion years.

Answer 3

First the depleted Uranium used as antitank rounds has NEVER been in a nuclear reactor.

Second as you point out the spent fuel that comes out of a reactor still has some potential to create electricity. When fuel is put in a reactor it is burned for some amount of time until either to many poisons build up in the fuel slowing down the chain reaction or the fuel becomes materially damaged and has to be removed. In either case we can chemically treat fuel and make it use able. And this would significantly reduce the waste. Despite what other people have said, the technology exists to do this safely. Some countries do reprocess, France is one and their entire nuclear waste is stored in a room the size of a gym.
Currently the US government prevents the industry from reprocessing, but this might change soon.

Answer 4

You suffer from a common misconception. It isn't the radiation in fissionable material that generates electricity.
The way it works is that the fissionable material generates heat, the heat runs a glorified steam turbine. So far as I know there is no known way to transform ionizing radiation into electrical energy on any useful level.

There is, in truth, a great deal of nuclear waste because the industry never really solved the problem. Some of this is political (ever heard of Not in MY Backyard?); but mostly it's economy. Nuclear energy never proved to be as efficient as was promised and so not enough money was set aside to manage the wastes, decommission the old plants or adequately fund the research about waste disposal.

To be fair, there have been some technologies tried out, but most have them have proven either too expensive, or not adequate for the long term storage. remember that many of these wastes have to be isolated from the environment for hundreds, if not thousands of years.

The fact of the matter is that a great deal of the waste generated by individual reactors sits in gigantic swimmingpool-like holding ponds right next to the reactors that generate the waste. This is a serious hazard and we are all downright lucky nothing serious has happened yet at these locations.

Personally I would support nuclear energy if I saw the industry be more honest and accountable about this particular issue. Run competently nuclear plants are an excellent energy supplier. Run shortsightedly and they are just another dead-end approach to the energy problem.

Answer 5

A nuclear power plant works by using the heat generated in the nuclear fission reaction to boil water, and using the steam to turn a turbine. Radioactivity is the relatively slow, natural decay of matter, which does not release any appreciable amount of heat. So, in other words, what is needed is material that is easily fissionable (like Uranium 235), not material that is radioactive. Radioactivity is, more or less, a side-effect.

Answer 6

I really have to laugh at your question. boy oh boy oh boy