Why radioactive waste is "waste"?

[Chupacabras]

Totally lost here, but I believed that radiation was "the" thing that made radioactive material useful for energy, so if nuclear waste is still radioactive, why would it be a waste?

Surely, many real geniuses have pondered long and hard about this, but I still think that there should be something useful that could be done with it (of course, with all due care).

 

[geni]

Its not the radation relised by nuclear fuel that makes it useful. The energy comes from the amount of mass lost when a large atom is split acordind to the equation E=mC^2. In normal radioactive waste there are three elements in it that are fisile u-235, plotonium and amricarnium one these have been extacted the only sorce of energy is from straight forward radioactive decay.
The main problems with extracting energy from this sorce are that first we cannot contoll it. Secondly only high level waste is would provide enogh energy to make this remotly feasable. The problem with that is that high level waste is top of the list of " stuff you do not want to have anything to do with". Finaly evern with high level waste the amount of energy you would get would be severel orders of magnetude lower than you get from fusion.

 

[davefoc]

geni,
Could you talk about how reprocessing of nuclear fuel fits in.

Does the reprocessing have a significant impact on the amount of radioactive waste.

 

[epepke]

Totally lost here, but I believed that radiation was "the" thing that made radioactive material useful for energy, so if nuclear waste is still radioactive, why would it be a waste?

As geni pointed out, the value of radioisotopes for power generation is based on the ability to have a sustainable, controlled chain reaction. Only a few radioisotopes qualify.

Of course, radioisotopes may be useful for other things, such as ionizing smoke detectors and medicine, but the market for these is so small compared to the market for power that there really isn't an impetus to find a use for every radioisotope.

 

[geni]

geni,
Could you talk about how reprocessing of nuclear fuel fits in.

Does the reprocessing have a significant impact on the amount of radioactive waste.

Reprocessing involves removing left over U235 from fuel rods along with plutonium. Since these these two are far less radioactive than some of the other stuff in spent fuel rods the resulting waste becomes evern more radioactive (ie this stuff is safe from terroists because if they get near it it will kill them)

 

[Ranb]

Here is what I remember from the Navy's nuclear power school back in 1984. Since it was a course based on algebra, it was rather basic, but here goes.

geni is correct about the energy resulting from the lowering mass of the fuel after fission (increase in binding energy, right?). The fission fragments are highly radioactive and actually give off about 10% of the reactor's power history for a short time. When fission products or activated corrosion products are transferred to an unwanted area, (leaks, plant dismantling) the contamination is just an undesireable occurance. The fission products have a much shorter half-life than uranium, so the activity is very high.

To be useful, many radioactive sources are manufactured from a pure metal which is exposed to a neutron flux then safely encased in a leakproof container. These sources can then be used to test radiation detectors, nuclear pharmicuticals, or cameras for testing weld joints. Depending on the task, a long or short half-life may be desired.

To just scrape together radioactive waste into a container would not serve much use because the strength and decay rate would not be easily known. Too many decaying isotopes are present.

Re-processsing spent reactor fuel results in much contaminated equipment and waste products. Much of the hardware can be reused and remain contaminated. But the U235 fission products are not useful for anything and have to be disposed of in a safe manner.

I would disagree that the waste from spent fuel is not useful for a terrorist. It can be shield and carted away. Not something I want to do though.

Ranb

 

[Eos of the Eons]

[sarcasm] Irradiating food is a conspiracy to use up nuclear waste don't ya know[/sarcasm]

-woo woo logic drives me nuts. Makes it sound like that's the only way to irradiate food or something.

 

[Chaos]

I don´t think the shielding would be much of a problem for terrorists.

To quote a Tom Clancy (I think) novel:
"They have no problems to find people that blow themselves up for their cause. So they should be able to find twenty people that are ready to die from cancer for their cause."

 

[geni]

I don´t think the shielding would be much of a problem for terrorists.

To quote a Tom Clancy (I think) novel:
"They have no problems to find people that blow themselves up for their cause. So they should be able to find twenty people that are ready to die from cancer for their cause."

You had better hope your wrong on this as there is whole load of russian nuclear waste protected in precicly this manner. Cancer is not the problem. The firemen who died of radition poisening after Chenovel did not die of cancer. The radation levels they were exposed to were still below the level you would be exposed to in you tried to acces this waste.

 

[Chupacabras]

Originally posted by geni ... Cancer is not the problem. The firemen who died of radition poisening after Chenovel did not die of cancer.

Even aside from poisoning, I understand this material is really HOT - it must be handled in proper containers and these in turn handled with machinery.

After reading the prompt and very helpful posts in this thread, I was thinking that it was precisely heat that could turn out to be useful (ie: deep drilling on ice). But then again, there would be a lot of trouble handling and eventually taking care of the material... No wonder why the USA government is pushing for the Yucca Mountain project.

 

[tracer]

Cecil Adams' Straight Dope article on nuclear waste.

Summary: There are two kinds of radioactive waste -- high-level waste and low-level waste. Only high-level waste consists of spent nuclear fuel. Most of the radioactive waste produced is of the low-level variety: contaminated gloves and tools, the residue from medical tests and experiments, etc..

 

[geni]

Cecil Adams' Straight Dope article on nuclear waste.

Summary: There are two kinds of radioactive waste -- high-level waste and low-level waste. Only high-level waste consists of spent nuclear fuel. Most of the radioactive waste produced is of the low-level variety: contaminated gloves and tools, the residue from medical tests and experiments, etc..

You forgot mid level waste which mainly consists of spent fuel rod casings. This stuff is too radioactive for low level disposal but doesn't quite need the care in handerling the high level stuff does.

 

[Agammamon]

Reactors are not a one size fits all solution. The shape of the core is determined by the fuel. It is possible to use waste as fuel (ie Plutonium reactors) but each type of waste isotope would need it's own core design. Potentially you could do this until the Iron limit but as you can imagine, it gets prohibitivley difficult to design reactors for the thousands of waste product produced.