How many nuclear power plants would we need to get us to 100%

[Altair_IV]

17. Numerous errors and misconceptions..

madokie,

Evidently you don't realize that even if you don't put MOX into a nuclear power plant; about 40% of the energy that one derives comes from fissioning Plutonium that was created "in situ". In other words, if you fuel a plant with MOX, you are just putting back some of the material that you previously took out and you give that material a "second chance" to be burned. Even if you fuel a reactor with Uranium as the only fissile material; the reactor starts making MOX "in situ". So there's really no problem with using MOX in power reactors; they were designed for it, and they make MOX anyway, whether you load it in or not.

You are also in error about the effect of reprocessing on the need for a geologic repository. The need for a geologic repository is mandated by the long half-lives of the actinides, principally the 24,100 year half-life of Plutonium-239. However, if you reprocess; you return all the actinides to the reactor to be burned. Therefore, you don't have actinides in the waste stream. The waste consists *only* of fission products, which are the true nuclear "ash". The lifetimes of fission products are less than a few decades, hence reprocessing obviates the need to store waste for geologic times. The *only* time a geologic repository that can store waste for thousands of years is when a "once through" nuclear waste policy has been mandated. The US Congress mandated a "once through" fuel cycle in a series of Nuclear Waste Policy Acts passed decades ago at the behest of the antinuclear movement.

The above poster made another egregious misstatement above in saying that nuclear power plants required much more water than does a coal or gas-fired power plant. That is just not true. The Rankine steam cycle for nuclear and coal- or gas-fired plants is quite similar; the fossil fuel fired boiler of the fossil fuel plant is simply replaced by a nuclear reactor and nuclear steam supply system. Within the nuclear steam supply system; the coolant water is pumped in a closed loop and isn't "used up".

Compare the following schematics of a nuclear and fossil fueled power plants:

http://www.nrc.gov/reading-rm/basic-ref/students/animated-pwr.html

and

http://ga.water.usgs.gov/edu/wupt-coalplant-diagram.html

The only water that may not recycled in a continuous loop is the water used to cool the condenser; which is exactly the same in the two types of power plant. The condenser coolant can either be cooled by running it to a cooling tower as in the fossil fuel plant diagram. The water is recycled with the addition of make up water to account for the water evaporated from the cooling tower.

The condenser coolant may also be withdrawn from a lake or river, and returned to same lake or river at a somewhat elevated temperature. Either way, water is not "used up". Even the water that is evaporated in cooling towers eventually returns as rain.

Altair_IV