by A swedish kind of death
Wed Dec 7th, 2011 at 04:35:45 PM EST
Cyrille linked a Monbiot article in the Salon which caused some discussion, a lot on other things. In an attempt to refocus the discussion, here comes a diary.
A bit of history
In 1995 Carlo Rubbia et al wrote a paper ("Conceptual Design 0f a Fast Neutron Operated High Power Energy Amplifier") on how to use a controlled decay-path for nuclear isotopes. The basic difference between an energy amplifier and a fission reactor is that the energy amplifier does not have a self-sustained reaction so no risk of meltdown. I remember this well as my younger self was very excited and saw a simple solution to every energy problem the world faced, including what to do with nuclear waste - feed it into the energy amplifier. One problem solved!
As I got older (and a fair bit more cynical) energy amplifiers first changed brand to Thorium reactors, then to 4th generation nuclear power and now apparently integral fast reactors. Actual reactors have however not been built.
I am going to quote from Wikipedia's article on Energy amplifiers
The concept has several potential advantages over conventional nuclear fission reactors:
- Subcritical design means that the reaction could not run away -- if anything went wrong, the reaction would stop and the reactor would cool down. A meltdown could however occur if the ability to cool the core was lost.
- Thorium is an abundant element -- much more so than uranium -- reducing strategic and political supply issues and eliminating costly and energy-intensive isotope separation. There is enough thorium to generate energy for at least several thousand years at current consumption rates.
- The energy amplifier would produce very little plutonium, so the design is believed to be more proliferation-resistant than conventional nuclear power (although the question of uranium-233 as nuclear weapon material must be assessed carefully).
- The possibility exists of using the reactor to consume plutonium, reducing the world stockpile of the very-long-lived element.
- Less long-lived radioactive waste is produced -- the waste material would decay after 500 years to the radioactive level of coal ash.
- No new science is required; the technologies to build the energy amplifier have all been demonstrated. Building an energy amplifier requires only some engineering effort, not fundamental research (unlike nuclear fusion proposals).
- Power generation might be economical compared to current nuclear reactor designs if the total fuel cycle and decommissioning costs are considered.
- The design could work on a relatively small scale, making it more suitable for countries without a well-developed power grid system
- Inherent safety and safe fuel transport could make the technology more suitable for developing countries as well as in densely populated areas.
This list has significantly more qualifiers then later lists, like the one on Generation IV reactors
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
- Nuclear waste that lasts a few centuries instead of millennia 
- 100-300 times more energy yield from the same amount of nuclear fuel 
- The ability to consume existing nuclear waste in the production of electricity
- Improved operating safety
To sum up the advantages: it is better then current nuclear on safety issues, and might be better economically.
Now, there are still no reactors, so what is the problem?
Lets check Wikipedia
- General technical difficulties.
- Each reactor needs its own facility (particle accelerator) to generate the high energy proton beam, which is very costly. Apart from linear particle accelerators, which are very expensive, no proton accelerator of sufficient power and energy (> ~12 MW at 1GeV) has ever been built. Currently, the Spallation Neutron Source utilizes a 1.44 MW proton beam to produce its neutrons, with upgrades envisioned to 5 MW. Its 1.1 billion dollar cost included research equipment not needed for a commercial reactor.
I think general technical difficulties should not be underestimated. The current estimate is according to Wikipedia
Generation IV reactors (Gen IV) are a set of theoretical nuclear reactor designs currently being researched. Most of these designs are generally not expected to be available for commercial construction before 2030.
Twenty years into the future is basically in the "we hope we will get it working" category.
If developed I think that it is more likely to run on freshly mined Thorium then on nuclear waste, but in general I think this technology will stay in the future.
What do you think?