National Academy of Engineering: Yucca could displace 1 trillion tons of

[NNadir]

coal.

The Yucca Mountain "nuclear waste" repository, which I am on record as opposing, is designed for the stupid "once through" nuclear cycle, wherein uranium is used one time and then dumped.

I am an advocate of advanced fuel cycles that do not feature a "waste mentality," and I think the world is coming around at this late date to my way of thinking.

Still, it happens that it is somewhat unlikely that all fission products will be transmuted into valuable materials and that ultimately some small geological disposal technology will be required for some nuclear materials. I think that the current approach on this subject is somewhat overly pessimistic, but I concede that it may be difficult to transmute all of the cesium-135 contained in reactors, and I believe that the main use for this isotope that I envision, in ion propulsion engines, is not likely to be widely adopted.

I am convinced that geological repository facilities can be operated at minimal (or even essentially zero) risk to the future, and I base my confidence on the modern understanding of the ancient naturally occurring reactors that operated at Oklo in Gabon almost 2 billion years ago. That said, I think the proclivity to rush into these kinds of choices, given that spent nuclear fuel has caused zero injuries, is just short of ridiculous.

It seems to me that more waiting and analysis is justified.

Here is an intriguing report from the National Academy of Engineering that obviates what I am talking about:

Technical Capacity: Advanced Fuel Cycles
It is technically possible for AFCs to recycle and transmute almost all of the heavy actinide elements that contribute to decay heat, leaving only fission products and residual actinides for disposal. Only two of the fission-product isotopes- strontium(Sr)-90 and cesium(Cs)-137, both of which have 30-year half- lives - would contribute significantly to the remaining decay heat. Because these isotopes have relatively short half lives, it is technically possible to separate and manage them separately for the 200 to 300 years required for their nearly complete decay. Separation and separate management of Cs-137 and Sr-90 have already been demonstrated at large scale at the Hanford site in Washington state, where both cesium and strontium recovered from high-level waste are currently stored separately in sealed capsules.6

Without cesium and strontium, the remaining fission products and residual actinides that require geologic disposal have very small rates of decay-heat generation. Thus, it becomes relatively easy to estimate the capacity of the Yucca Mountain site. If the current canister design for defense high-level waste (capable of holding five 60-cm diameter cylinders of borosilicate waste glass) were used to hold fission products, the fission-product loading could be 500 kg/m of drift tunnel length;7 this is 7 times greater than the fission-product loading for current 21-assembly PWR canisters. A 1-GW(e) light-water reactor (LWR) (whether a BWR or PWR), which can produce energy for one million typical homes, also produces approximately 1,080 kg of fission products per year. Slightly more than two meters of Yucca Mountain drift could hold a year's fission products from a plant this size.

At 2,000 acres, the Yucca Mountain site could have 100 km of drift tunnels spaced at 81 m. Without decay heat, the spacing could be reduced to 20 m, thus increasing the drift tunnels to 400 km. Using the existing defense-waste canister design, these drift tunnels could then hold 200,000,000 kg of fission products, the energy equivalent of burning one trillion tons of coal. This means that a single Yucca Mountain could replace 170 years of current, total, worldwide coal consumption.8

The bold is mine.

http://www.nae.edu/nae/bridgecom.nsf/weblinks/MKEZ-5S3Q6M?OpenDocument

[mom cat]

1. To say that spent nuclear fuel has caused zero injuries omits the

issues surrounding depleted uranium. Otherwise, I think you make some important points. If we were not in a world where a madman is in charge of the most powerful nation on the planet, I might be inclined to have more confidence in nuclear energy. As things stand now, however, I fear that more nuclear energy just meens moer material for warheads.

[Massacure]

2. Depleted Uranium is used as a weapon of war.

Isn't it a bit unfair to use that fact against it when debating peaceful nuclear technology? Besides, it can be put into breeders and transmuted to Plutonium which is then fissioned off.

[mom cat]

3. In this political climate, you can't discuss peacetine nuclear use wihout

dealing with the nuclear weapons aspect. Witness what is going on in Iran right now. They are developing nuclear technology and so far there is no evidence that they are gearing up to make weapons. But nince peacetine nuclear energy and nuclear weapons both start out at the same place, our govt's suspicions are running high.

[NNadir]

4. But an educated public would be perfectly willing to discard that

nonsensical association.

Indeed, an educated public would be more concerned with global climate change than a putative evocation of nuclear war, since global climate change is something that is real.

It's not something that might happen. It is very much something that is happening.

[Odin2005]

6. We should all go back to the stone age because all tech can be abused!!!

:sarcasm:

[Dead_Parrot]

5. That's a little like saying wood is deadly...

...because of the longbow. Sadly, humanity is wonderfully inventive when it comes to killing each other, and I'm sure we've barely scratched the surface.

Joe 3:10 Beat your plowshares into swords, and your pruning hooks into spears: let the weak say, I strong.