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Yucca Mountain Geothermal

Get more bang for your buck from nuclear power.
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OK. Everyone knows that nuclear power plants work by the fission of uranium that heats water to drive turbines. And geothermal works by pumping water down into the crust to hot rocks, and having superheated steam come back up. Idea!

If spent fuel rods and all the other nasties from reactors make a lot of heat when they decay, then why not use it to boil water and drive turbines? So here's the plan. Instead of building a very expensive waste disposal bunker under Yucca Mountain, Nevada, you instead construct a large, graphite-lined chamber. Simply dump all the nuclear waste in there and have two holes going from the chamber to the surface. Install a valve in one of them. Then, pour water down the hole that has a valve and wait. The super-hot waste products will vapourize the water instantly and blast it up the other hole as superheated(radioactive) steam! Use this to drive turbines which drive generators. You'd probably have to have a heat exchanger to avoid the turbines becoming nuclear waste themselves. What's better is eco-friendly power for the next 10,000 years! Well, relatively, compared to fossil fuels.

loopquanta137, Aug 28 2006

Another halfbaked method: Nuclear Powered Turbo-Reciprocating Engine http://www.popularm...search/1281696.html
[ldischler, Aug 28 2006]

Nuclear Fuel Cycle on Wikipedia http://en.wikipedia.../Nuclear_fuel_cycle
[jmvw, Sep 01 2006]

[link]






       Most nuclear waste doesn't produce much heat, unfortunately. Just as a reactor doesn't produce much heat until it goes critical.
ldischler, Aug 28 2006
  

       Unless used in the wrong hands.
skinflaps, Aug 28 2006
  

       Specifically, my hands.
loopquanta137, Aug 28 2006
  

       You appear to be inventing a nuclear power plant...that runs on spent nuclear fuel. Sounds like crazy science.
Texticle, Aug 29 2006
  

       Im not sure but I think they call it "spent" fuel for a reason.
jhomrighaus, Aug 29 2006
  

      
Some back of the envelope calculations:

A nuclear power plant produces about 1000 megawatts, which is worth about $2.5 million/day. A charge of uranium lasts about 4 years.

The used rods are contaminated with plutonium, with a half-life of 24,000 years. Assuming the plutonium has as much energy as the burned uranium, the waste rods are putting out 4/24,000 times the heat energy, or 1/6000 as much.

The waste energy plant is not capable of getting to the operational temps of a critical mass, so the efficiency will be less, but I’ll be generous and make it half as much, so that the electrical production is 1000 megawatts/12000. Which is 83 kilowatts. This is worth about $200/day. The cost of one operator for one day will be twice that, at least.
ldischler, Aug 29 2006
  

       [ldischler], I apologize if I'm not seeing everything here, but your calculation does not seem useful as an estimate. How much U-235 turns into plutonium through beta decay? Not that much? Also, would decay below a chain reaction really be less efficient? Wouldn't it just produce less heat over a longer amount of time? By reducing coolant circulation and possibly adding insulation you could still have the same working temperature.   

       [loopquanta137], I don't think the spent fuel just goes in a barrel and into storage. It's reprocessed to extract useful lefovers. Link shows a bit of fuel life cycle. According to that article "In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant".
jmvw, Sep 01 2006
  

       For the AIChE conference this year the undergraduates had to design a crystallization process for the recovery of spent nuclear fuel (SNF). I think our payback analysis was 166 years.
daseva, Sep 01 2006
  

       + for this idea because it made me learn a little.
jmvw, Sep 01 2006
  

      
//How much U-235 turns into plutonium through beta decay? Not that much?//
That's right, but I wanted to err on the high side. You still have burnable uranium left, but that wouldn't create much heat, and you have a number of other isotopes that burn off very quickly. So plutonium would be your main heat source for the ten thousand years.
//Also, would decay below a chain reaction really be less efficient?//
It would take a lot longer, that's for sure.
//Wouldn't it just produce less heat over a longer amount of time?//
Obviously. But it's a ridiculously small amount of thermal power. Even if you could get the conversion efficiency up to the level of a genuine power plant, your income still wouldn't pay for an operator.
ldischler, Sep 01 2006
  
      
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