http://www.newscientist.com/article/mg20227051.500-zapping-rubbish-into-ecofuel.html?DCMP=NLC-nletter&nsref=mg20227051.500

There does seem to be too much conflation in the article between ‘gasification’ and the much higher temperature ‘plasma gasification’ — the latter avoids most of the flaws of the former, though might be a bit more expensive until commercialised on a large scale.

“This is done at 15–25 MPa (150–250 bar) and between
300 and 550 °C”

It’s not like you have to have people shepherding these things along to keep them running. They pretty much work as on autopilot. The increase in capacity factors in the USA had to do with improvements in technology, not in training.

Solar thermal plants with their much lower thermal load are almost always air cooled.

As I’ve said before, the cooling requirements for CSP per kWh produced are the same as for nuclear, coal, or gas. If solar can do it all air-cooled it’s because they produce so little power. You can’t have your cake and eat it too.

Seawater nuclear plants are restricted by the amount of acceptable sites near cities that are already not being used by desalination.

You’d use IFRs for both, they’d be dual-use plants. That way they can be used for peaking very easily. You’d run them at full power all the time, varying the amount of heat channeled to each purpose as the electrical demand requires. That way you avoid having to throttle them back. Others would be dual-use for vehicle fuel (boron, or hydrogen for ammonia-powered vehicles). Likewise that would allow them to run at 100% while still being highly responsive for load-following, obviating the need for natural gas plants for peaking. It’s the multipurpose aspect of this that makes IFRs so ideal. As is they’re still very good at load-following, but dual-use makes them every bit as responsive as gas, or even better.

Energy efficiency, as you suggest, is the low-hanging fruit that should definitely be pursued.

It would take more effort to just separate pure Pu from the IFR fuel mix, than to make a simple well known graphite pile with natural uranium, and after low burn-up obtain a superior weapon grade Pu. Decades old and known technology needed, low radioactivity involved, proved and available (declassified) warhead designs, no major R&D issues.

Even after much more involved (due to intense radioactivity) separation of Pu from the IFR fuel, one would end up with vastly inferior material, which even if it could perhaps theoretically explode, practical problems such as the need for heavily shielded robotic manufacturing and machining of the warhead, problems with heat dissipation of the RG-Pu fuel nearby explosives, radiation damage to warhead electronics, and ease of weapon detection through intense radiation signature, present significant obstacles.

As shown by isolated and starving North Korea, if any government decides to acquire nuclear weaponry, there is no real technological challenge in repeating the 60 years old process, independently of any nuclear energy for electricity in either case.

Therefore the issue of nuclear weapons proliferation is an issue of international politics, and it’s tie to commercial nuclear energy is only indirect – societies with abundant affordable clean domestic power producing infrastructure are much less conductive to conflicts than societies impoverished, starved for energy, or dependent on energy imports from unstable or hostile regions.

There are other issues with nuclear materials than proliferation, including radio sources for medical or other uses, and all these materials need to be accounted for in a sane regulatory environment, similarly to explosives, fertilizers, etc., as is indeed the case.

Perhaps you can explain, why Australia burns more and more coal, now over 2x more than two decades ago, and about 4x more coal burned than 3 decades ago? This means that proportionally more dangerous fossil fuel wastes are produced, in spite of wishes.

Also, why does Germany, European leader in renewable energies, plans 26 new coal burning plants?

Apparently experience tells us that relying on prominent solar utopia dreamers in practice only solidifies the use of dangerous fossil fuels, as people become complacent that “wind/solar/fairy dust energy will solve our issues”, while in reality these resources are inadequate to contemporary energy needs, which can be demonstratively met by either combustion or fission.

I’ll take a look.

Trying again: here, table 7, one can learn that a CANDU fuel bundle, ten years after its retirement, can give a lethal radiation dose from 1 metre’s distance in 12 hours, as long as nothing denser than air is in the way.

[Ed: Thanks Graham - I also fixed your original link]

Here, table 7, one can learn that a CANDU fuel bundle, ten years after its retirement, can give a lethal radiation dose from 1 metre’s distance in 12 hours, as long as nothing denser than air is in the way.

CANDUs are water-cooled power reactors, and share that class’s historically perfect proliferation resistance, perhaps due to their excessive conversion of the plutonium-239 they produce to 240, 241, etc. If it were possible for a ten-years-retired CANDU bundle to fall off a truck, an informed malefactor would not need physical courage to scoop it off the roadside with his bare hands and hide it under his coat for a few minutes. But he would also know that no great mischief could be done with it. If nothing better than CANDU reactors ever turns up, they’re good enough to give the world many thousands of years of abundant clean bomb-unrelated energy.

As I understand the IFR idea, between taking fuel out of the reactor and reprocessing it you delay ten minutes rather than ten years; also, as it comes out, it has a much higher loading of fission fragments than CANDU fuel, a higher burnup. Say ten times higher.

That makes the radioactivity at any given post-removal time also ten times more, but this is a detail. The really big increase in radiation is due to the quickness with which the IFR operators would get it to the de-asher and get the de-ashed fuel back into service.

Adding in the estimated ten times greater burnup and we get the ashes in IFR fuel, just before they are removed from it, making it ~20000 times more radioactive than the ashes in CANDU fuel after ten years.

In terms of foiling a theft attempt, this 20000 is bound to be a slight underestimate, because the radiation from fast-decaying isotopes is more penetrating, less likely to be absorbed within the fuel itself. So dividing the 12 hours by 20000 gives us a conservative estimate of how quick the supposed thief, having neglected to bring a 50-tonne self-propelled shielding flask, will decide to sit down for a little rest, and never get up again: two seconds. Whoa, I hadn’t known it was that quick. But since this estimate is conservative, it’s probably quicker.

Of course, a half-dozen evil miracles would have to happen for him to get his tongs anywhere near a fuel rod during its brief, high-temperature journey from reactor to de-asher. Recall, the de-ashing in an IFR is also called pyro-processing. Not because of any combustion, rather, because it occurs at a high temperature.

(How fire can be domesticated)

The paper addresses a number of other anticides and isotopes. What are the fission products that make it too dangerous to handle?

It was shown qualitatively that an inherent radiation barrier could not be considered as a severe obstacle for a would-be proliferator to make an explosive device. This is proved to be true for other plutonium of any conceivable isotopic composition and minor actinides.”